技术领域Technical Field
本发明涉及一种无线电力传送装置，尤其涉及一种将连接于高频电源的一次线圈(coil)、及连接于负载的二次线圈以耦合系数k加以隔离而配置，而自一次线圈对二次线圈非接触地供给电力的无线电力传送装置。The present invention relates to a wireless power transmission device, and more particularly to a wireless power transmission device in which a primary coil connected to a high-frequency power source and a secondary coil connected to a load are separated by a coupling coefficient k and power is supplied from the primary coil to the secondary coil in a contactless manner.
背景技术Background Art
近年来，自提倡磁场谐振(磁谐振)方式的无线电力传送(非接触供电)以来，其应用迅速扩大。尤其，一次线圈与二次线圈之间的耦合系数k小、并且所述耦合系数k也大幅变化的情况下的线圈间的电力传递受到诸多重视。In recent years, the advent of wireless power transmission (contactless power supply) using magnetic field resonance (magnetic resonance) has seen a rapid expansion in its application. In particular, much attention has been paid to power transfer between primary and secondary coils when the coupling coefficient k between the coils is small and when this coupling coefficient k varies significantly.
图24是表示现有的磁场谐振方式的无线电力传送装置的构成的方块图，图25表示其等效电路图。FIG. 24 is a block diagram showing the configuration of a conventional magnetic field resonance type wireless power transmission device, and FIG. 25 is an equivalent circuit diagram thereof.
无线电力传送装置200包含一次侧电路(Source Electronics，电源侧电子器件)210、及二次侧电路(Device Electronics，设备侧电子器件)230。The wireless power transmission device 200 includes a primary-side circuit (Source Electronics) 210 and a secondary-side circuit (Device Electronics) 230 .
一次侧电路210包含：交流/直流(Alternating Current/Direct Current，AC/DC)转换电路213，将自交流(AC)电源(AC Mains)211供给的交流转换为直流；高频驱动电路215，将所述直流(DC)转换为规定的高频(RF，Radio Frequency，射频)，进行放大并加以输出；一次侧谐振器(Source Resonator，电源侧谐振器)219，被供给所述高频作为驱动电力；以及阻抗匹配电路(Impedance Matching Networks，IMN)217，在与所述一次侧谐振器219之间进行阻抗匹配。The primary-side circuit 210 includes an alternating current/direct current (AC/DC) conversion circuit 213 that converts alternating current (AC) supplied from an AC mains 211 into direct current (DC); a high-frequency drive circuit 215 that converts the DC into a predetermined high frequency (RF, radio frequency), amplifies the amplified DC, and outputs the amplified DC; a primary-side resonator (source resonator) 219 that receives the high frequency as driving power; and an impedance matching network (IMN) 217 that performs impedance matching with the primary-side resonator 219.
二次侧电路230包含：二次侧谐振器(Device Resonator，设备侧谐振器)231；阻抗匹配电路(IMN)233；RF/DC整流电路(RF/DC Rectifier)235，其将高频(RF)转换为直流，进行整流并输出；以及负载(Load)237，其被供给经整流的直流电力。The secondary-side circuit 230 includes a secondary-side resonator (device resonator) 231 , an impedance matching circuit (IMN) 233 , an RF/DC rectifier circuit 235 that converts high-frequency (RF) power into DC power, rectifies the power, and outputs the DC power, and a load 237 that receives the rectified DC power.
一次侧谐振器219包含一次线圈、及一次谐振电容器(condenser)，二次侧谐振器230包含二次线圈、及二次谐振电容器。The primary-side resonator 219 includes a primary coil and a primary resonant capacitor, and the secondary-side resonator 230 includes a secondary coil and a secondary resonant capacitor.
在磁场谐振方式的无线电力传送中，通过使一次侧谐振器219与二次侧谐振器231的谐振频率一致，使双方的谐振器彼此谐振，而即便在距离远的线圈间也可实现高效率的电力传送。In magnetic field resonance wireless power transmission, by aligning the resonant frequencies of the primary resonator 219 and the secondary resonator 231 , both resonators resonate with each other, enabling highly efficient power transmission even between coils at a distance.
另外，磁场谐振方式中，通过使用阻抗匹配电路(IMN)217及阻抗匹配电路(IMN)233分别使阻抗条件匹配，来控制各个谐振器219及谐振器231。In the magnetic field resonance method, the impedance matching circuit (IMN) 217 and the impedance matching circuit (IMN) 233 are used to match the impedance conditions, thereby controlling the resonators 219 and 231 .
在图25所示的等效电路图中，一次侧电路210的Vg、Rg、Cs、Ls、Rs分别表示高频驱动电压、高频驱动电路的等效电阻、谐振电容器的电容(capacitance)、一次线圈的自感(self-inductance)、及一次线圈的等效电阻，二次侧电路的RL、Cd、Ld、Rd分别表示负载的等效电阻、谐振电容器的电容、二次线圈的自感、及二次线圈的等效电阻。另外，M表示一次线圈与二次线圈之间的相互电感。In the equivalent circuit diagram shown in FIG25 , Vg, Rg, Cs, Ls, and Rs of the primary-side circuit 210 represent the high-frequency drive voltage, the equivalent resistance of the high-frequency drive circuit, the capacitance of the resonant capacitor, the self-inductance of the primary coil, and the equivalent resistance of the primary coil, respectively. RL, Cd, Ld, and Rd of the secondary-side circuit represent the equivalent resistance of the load, the capacitance of the resonant capacitor, the self-inductance of the secondary coil, and the equivalent resistance of the secondary coil, respectively. Furthermore, M represents the mutual inductance between the primary and secondary coils.
此处，在磁场谐振方式中，需要包含图24所示的一次侧谐振器219，这是磁场谐振方式的最大特征。因此，如图25所示，一次谐振电容器Cs成为必需的构成要素。Here, the magnetic field resonance method needs to include the primary-side resonator 219 shown in FIG24 , which is the greatest feature of the magnetic field resonance method. Therefore, as shown in FIG25 , the primary resonant capacitorCs becomes an essential component.
若原理上考察无线电力传送，则可使包含一次线圈与二次线圈的漏磁通变压器(transformer)的耦合系数k变化，且负载也同时变化。另外，对于无线电力传送，若着眼于构成其的电子电路，则变化的磁参数(parameter)多，因此可以说非常难以同时实现高效率与稳定度、可靠性等。进而，在近年来的电磁相容性(Electro-Magnetic Compatibility，EMC)限制下，还有必要引入用以减少噪声电力(噪声电场强度)的软开关(soft switching)方式即零电压开关(Zero Voltage Switching，ZVS)技术。If we examine wireless power transmission in principle, the coupling coefficient k of the leakage flux transformer (transformer) consisting of the primary and secondary coils can be varied, and the load can also be varied simultaneously. Furthermore, when considering wireless power transmission, the electronic circuits that constitute it have many varying magnetic parameters, making it extremely difficult to simultaneously achieve high efficiency, stability, and reliability. Furthermore, under recent electromagnetic compatibility (EMC) regulations, it is necessary to introduce a soft switching method, namely zero voltage switching (ZVS), to reduce noise power (noise electric field strength).
因此，自电力控制的观点而言，即便欲求出驱动电路的构成要素的参数的最佳值，也多有各参数值未必协调，成为取舍(trade off)的关系而相互竞争，因此极其难以同时实现各参数的最佳值。Therefore, from the perspective of power control, even if one attempts to find optimal values for the parameters of the components of the drive circuit, the parameter values are often not necessarily coordinated, resulting in a trade-off relationship and competition with each other. Therefore, it is extremely difficult to simultaneously achieve the optimal values for each parameter.
因此，现有的无线电力传送中，通过牺牲任一参数而实现电力控制。另外，关于无线电力传送中传送的电力的大小，当前虽已获得有实用性的值，但进行驱动的一次线圈中的发热大成为问题。所述发热几乎均由铜耗造成，所述铜耗的克服成为课题。Therefore, conventional wireless power transmission achieves power control by sacrificing any one parameter. Furthermore, while practical values for the amount of power transmitted in wireless power transmission have been achieved, significant heat generation in the primary coils that drive the power supply has become a problem. This heat generation is largely due to copper loss, and overcoming this copper loss remains a challenge.
在无线电力传送中，在使一次侧与二次侧双方具有谐振电路的情况下，一次侧的谐振频率与线圈间的距离无关而为固定，但关于二次侧的谐振频率，在线圈间的距离改变而耦合系数变化的情况下，谐振频率也改变。将其表示为数式，则若将二次线圈的电感设为L2，将谐振电容器设为Cp，将耦合系数设为k，则成为：In wireless power transmission, when resonant circuits are provided on both the primary and secondary sides, the resonant frequency on the primary side remains constant regardless of the distance between the coils. However, the resonant frequency on the secondary side also changes when the distance between the coils changes and the coupling coefficient changes. Expressing this numerically, if the inductance of the secondary coil is L2 , the resonant capacitor is Cp, and the coupling coefficient is k, the result is:
[数1][Number 1]
因此，现有的磁场谐振方式中，仅在线圈间的距离为预先规定的距离的情况下一次侧与二次侧的谐振频率一致，在为除此以外的线圈间距离时谐振频率不一致。Therefore, in the conventional magnetic field resonance method, the resonant frequencies of the primary side and the secondary side match only when the distance between the coils is a predetermined distance, and the resonant frequencies do not match at other distances between the coils.
因此，在一次线圈与二次线圈具有规定的位置关系的情况下可获得实用上充分的效率，但若线圈间距离远离预先规定的固定的距离关系，或一次线圈与二次线圈的中心轴偏移，则自一次线圈观察到的功率因素急剧恶化。在所述情况下，存在虽可进行电力传送但效率差，而发热进一步增加的问题。Therefore, while sufficient efficiency can be achieved for practical purposes when the primary and secondary coils maintain a predetermined positional relationship, if the inter-coil distance deviates from the predetermined fixed relationship, or if the central axes of the primary and secondary coils are offset, the power factor observed from the primary coil deteriorates dramatically. In these situations, while power transmission is possible, efficiency is low, and heat generation further increases.
进而，还存在如下问题：为了确保驱动一次线圈的开关元件的ZVS动作，需要将一次线圈与二次线圈的相位关系限制于特定的范围内，而仅在非常有限的条件下才可进行ZVS动作。Furthermore, there is a problem that in order to ensure ZVS operation of the switching element driving the primary coil, the phase relationship between the primary coil and the secondary coil must be restricted to a specific range, and ZVS operation is only possible under very limited conditions.
因此，现有的无线电力传送为了恒定地确保ZVS动作，进行一面观察负载的状态一面依照一定的程序(program)使驱动频率可变等处理。Therefore, conventional wireless power transmission has been implemented to constantly ensure ZVS operation by varying the driving frequency according to a predetermined program while observing the load state.
[现有技术文献][Prior art literature]
[专利文献][Patent Document]
专利文献1：日本专利特开2002-272134Patent Document 1: Japanese Patent Application Laid-Open No. 2002-272134
专利文献2：日本专利特开昭63-73837Patent Document 2: Japanese Patent Application Laid-Open No. 63-73837
专利文献3：日本专利特开2011-97671Patent Document 3: Japanese Patent Laid-Open No. 2011-97671
专利文献4：日本专利第4921466号Patent Document 4: Japanese Patent No. 4921466
专利文献5：日本专利第5190108号Patent Document 5: Japanese Patent No. 5190108
发明内容Summary of the Invention
[发明要解决的问题][Problems to be solved by the invention]
本发明的目的在于解决伴随现有的磁场谐振方式的所述各种课题的一部分。An object of the present invention is to solve some of the various problems associated with the conventional magnetic field resonance method.
尤其，目的在于提供一种无线电力传送装置，在线圈间距离变化，或一次线圈与二次线圈的中心轴偏移等条件变化时，也可将自一次线圈的驱动单元侧与一次线圈的双方观察到的功率因素同时维持为良好的关系，从而可实现有效率的电力传送。In particular, the purpose is to provide a wireless power transmission device that can maintain a good relationship between the power factors observed from the driving unit side of the primary coil and the power factors observed from both sides of the primary coil when conditions such as the distance between the coils changes or the center axis offset between the primary coil and the secondary coil change, thereby achieving efficient power transmission.
另外，目的在于提供一种无线电力传送装置，通过自动获得进行有效率的电力传送的最佳驱动频率，而可利用简单的电路同时减少铜耗与开关损耗，高稳固(robust)性地进行高效率的驱动。Another object is to provide a wireless power transmission device that automatically obtains an optimal driving frequency for efficient power transmission, thereby reducing copper loss and switching loss with a simple circuit and performing highly robust and efficient driving.
[解决问题的技术手段][Technical means to solve the problem]
本发明的第1实施例是一种无线电力传送装置，将连接于高频电源的一次线圈、与连接于负载的二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并对流入至所述谐振电容器的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感(leakage inductance)、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A first embodiment of the present invention is a wireless power transmission device in which a primary coil connected to a high-frequency power supply and a secondary coil connected to a load are separated by a coupling coefficient k, and power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of a resonant current flowing into the resonant capacitor; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of a drive voltage applied to the primary coil. The device sets a Q value determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side to a value greater than or equal to Q = 2/k² .
本发明的第2实施例是一种无线电力传送装置，将连接于高频电源的一次线圈、与连接于负载的二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并对流入至所述二次线圈的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A second embodiment of the present invention is a wireless power transmission device in which a primary coil connected to a high-frequency power supply and a secondary coil connected to a load are arranged with separation by a coupling coefficient k, and power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of the resonant current flowing into the secondary coil; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of the drive voltage applied to the primary coil. The device sets a Q value determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side to a value greater than or equal to Q = 2/k² .
本发明的第3实施例是一种无线电力传送装置，将连接于高频电源的一次线圈、与连接于负载的二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并自所述一次线圈对流入至所述谐振电路的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A third embodiment of the present invention is a wireless power transmission device in which a primary coil connected to a high-frequency power supply and a secondary coil connected to a load are arranged with separation by a coupling coefficient k, and power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of a resonant current flowing from the primary coil into the resonant circuit; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of a drive voltage applied to the primary coil. The device sets a Q value determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side to a value greater than or equal to Q = 2/k² .
本发明的第4实施例是一种无线电力传送装置，将连接于高频电源的一次线圈、与连接于负载的二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并基于如下波形来检测谐振电流的相位信息，所述波形是将流入至所述谐振电容器的谐振电流的波形、流入至所述二次线圈的谐振电流的波形、或流入至所述一次线圈的谐振电流的波形中的任一波形、与将所述任一波形反转并积分所得的波形加以重叠合成所得；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A fourth embodiment of the present invention is a wireless power transmission device in which a primary coil connected to a high-frequency power source and a secondary coil connected to a load are separated by a coupling coefficient k, and power is supplied from the primary coil to the secondary coil in a contactless manner. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of the resonant current based on a waveform obtained by superimposing and synthesizing a waveform obtained by inverting and integrating any of the waveforms: a waveform of the resonant current flowing into the resonant capacitor, a waveform of the resonant current flowing into the secondary coil, or a waveform of the resonant current flowing into the primary coil; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of the drive voltage applied to the primary coil. The Q value, which is determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side, is set to Q = 2/k.2 or more of the values specified.
本发明的第5实施例根据第1实施例至第4实施例中的任一实施例，其包括滤波器(filter)，所述滤波器将所述谐振电流的波形中所含的失真去除，而仅提取基谐波。A fifth embodiment of the present invention, based on any one of the first to fourth embodiments, includes a filter that removes distortion included in the waveform of the resonant current and extracts only fundamental harmonics.
本发明的第6实施例根据第1实施例至第5实施例中任一实施例，其中所述驱动电路包含驱动所述一次线圈的开关单元，所述开关单元使ON-OFF(导通-断开)的占空比(dutyratio)可变，并基于所述相位信息而使所述开关单元ON，在固定时间后使开关单元OFF，由此进行电力控制。The sixth embodiment of the present invention is based on any one of the first to fifth embodiments, wherein the driving circuit includes a switching unit that drives the primary coil, the switching unit makes the ON-OFF duty ratio (duty ratio) variable, and turns the switching unit ON based on the phase information, and turns the switching unit OFF after a fixed time, thereby performing power control.
本发明的第7实施例根据第1实施例或第4实施例，其中所述谐振电流相位检测单元根据流入至并联连接于所述谐振电容器的小电容电容器的电流来检测所述相位信息。A seventh embodiment of the present invention is based on the first embodiment or the fourth embodiment, wherein the resonant current phase detection unit detects the phase information based on a current flowing into a small capacitance capacitor connected in parallel to the resonant capacitor.
本发明的第8实施例是一种无线电力传送装置，包括：一次线圈，连接于高频电源；二次线圈，连接于负载；以及第三线圈，接近所述二次线圈或作为自耦变压器(autotransformer)而包含于所述二次线圈，且以相对于所述二次线圈中感应的电压为降压的关系而卷绕，将所述一次线圈与所述二次线圈以耦合系数k加以隔离而配置，自所述一次线圈通过所述二次线圈而对第三线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并对流入至所述谐振电容器的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。An eighth embodiment of the present invention is a wireless power transmission device comprising: a primary coil connected to a high-frequency power supply; a secondary coil connected to a load; and a third coil proximate to the secondary coil or included in the secondary coil as an autotransformer and wound so as to step down the voltage induced in the secondary coil. The primary coil and the secondary coil are arranged so as to be isolated from each other by a coupling coefficient k, and power is supplied to the third coil in a contactless manner from the primary coil through the secondary coil. The wireless power transmission device is provided with a resonant current phase detection unit to detect the phase of the resonant current. A resonant capacitor is coupled to the secondary coil to form a resonant circuit, and detects phase information of a resonant current flowing into the resonant capacitor; a phase information transmission unit transmits the detected phase information without phase delay; and a drive circuit drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed compared to the voltage phase of the drive voltage applied to the primary coil, and setting a Q value determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side to a value greater than or equal to Q=2/k2 .
本发明的第9实施例是一种无线电力传送装置，连接于高频电源的一次线圈、连接于负载的二次线圈、接近所述二次线圈或所述二次线圈为自耦变压器，且以相对于所述二次线圈中感应的电压为降压的关系而卷绕的第三线圈成为包含于所述自耦变压器的关系，将所述一次线圈与所述二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并对流入至所述二次线圈的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A ninth embodiment of the present invention is a wireless power transmission device comprising a primary coil connected to a high-frequency power source, a secondary coil connected to a load, and a third coil, which is proximate to or wound to reduce the voltage induced in the secondary coil and is contained within the autotransformer, so that the primary coil and the secondary coil are isolated from each other by a coupling coefficient k. Electric power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of the resonant current flowing into the secondary coil; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that, based on the phase information, drives the primary coil by setting a drive frequency such that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of the drive voltage applied to the primary coil. A Q value, determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side, is set to Q = 2/k.2 or more of the values specified.
本发明的第10实施例是一种无线电力传送装置，连接于高频电源的一次线圈、连接于负载的二次线圈、接近所述二次线圈或所述二次线圈为自耦变压器，且以相对于所述二次线圈中感应的电压为降压的关系而卷绕的第三线圈成为包含于所述自耦变压器的关系，将所述一次线圈与所述二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并自所述一次线圈对流入至所述谐振电路的谐振电流的相位信息进行检测；相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器的电容、及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。A tenth embodiment of the present invention is a wireless power transmission device comprising a primary coil connected to a high-frequency power supply, a secondary coil connected to a load, and a third coil proximate to or wound to reduce the voltage induced in the secondary coil within the autotransformer. The primary coil and the secondary coil are isolated from each other by a coupling coefficient k, and power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes: a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of a resonant current flowing from the primary coil into the resonant circuit; a phase information transmission unit that transmits the detected phase information without phase delay; and a drive circuit that drives the primary coil by setting a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed relative to the voltage phase of the drive voltage applied to the primary coil. The Q value, determined by the leakage inductance of the secondary coil, the capacitance of the resonant capacitor, and the equivalent load resistance on the secondary coil side, is set to Q = 2/k.2 or more of the values specified.
本发明的第11实施例是一种无线电力传送装置，连接于高频电源的一次线圈、连接于负载的二次线圈、接近所述二次线圈或所述二次线圈为自耦变压器，且以相对于所述二次线圈中感应的电压为降压的关系而卷绕的第三线圈成为包含于所述自耦变压器的关系，将所述一次线圈与所述二次线圈以耦合系数k加以隔离而配置，自所述一次线圈对所述二次线圈非接触地供给电力，所述无线电力传送装置设置有：谐振电流相位检测单元，将谐振电容器耦合于所述二次线圈而构成谐振电路，并基于如下波形来检测谐振电流的相位信息，所述波形是将流入至所述谐振电容器的谐振电流的波形、流入至所述二次线圈的谐振电流的波形、或流入至所述一次线圈的谐振电流的波形中的任一波形、与将所述任一波形反转并积分所得的波形加以重叠合成所得，相位信息传递单元，无相位延迟地传递检测到的所述相位信息；以及驱动电路，基于所述相位信息，以使流入至所述一次线圈的驱动电流的电流相位较施加于所述一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动所述一次线圈，将由所述二次线圈的漏电感、所述谐振电容器及所述二次线圈侧的等效负载电阻所决定的Q值设定为Q＝2/k2所规定的值以上的值。An eleventh embodiment of the present invention is a wireless power transmission device comprising a primary coil connected to a high-frequency power supply, a secondary coil connected to a load, and a third coil disposed proximate to or wound around the secondary coil to reduce the voltage induced in the secondary coil, the third coil being included in the autotransformer. The primary coil and the secondary coil are isolated from each other by a coupling coefficient k, and power is supplied contactlessly from the primary coil to the secondary coil. The wireless power transmission device includes a resonant current phase detection unit that couples a resonant capacitor to the secondary coil to form a resonant circuit and detects phase information of the resonant current based on a waveform obtained by converting the resonant current flowing into the secondary coil. A phase information transmission unit transmits the detected phase information without phase delay, by superimposing and synthesizing any one of the waveforms of the resonant current of the resonant capacitor, the waveform of the resonant current flowing into the secondary coil, or the waveform of the resonant current flowing into the primary coil, and a waveform obtained by inverting and integrating any one of the waveforms; and a drive circuit drives the primary coil by specifying a drive frequency based on the phase information so that the current phase of the drive current flowing into the primary coil is slightly delayed compared to the voltage phase of the drive voltage applied to the primary coil, and setting a Q value determined by the leakage inductance of the secondary coil, the resonant capacitor, and the equivalent load resistance on the secondary coil side to a value greater than or equal to Q=2/k2 .
本发明的第12实施例根据第8实施例至第11实施例中任一实施例，其包括滤波器，所述滤波器将所述谐振电流的波形中所含的失真去除，而仅提取基谐波。A twelfth embodiment of the present invention is based on any one of the eighth to eleventh embodiments, and further includes a filter that removes distortion included in the waveform of the resonant current and extracts only fundamental harmonics.
本发明的第13实施例根据第8实施例至第12实施例项中任一实施例，其中所述驱动电路包含驱动所述一次线圈的开关单元，所述开关单元使ON-OFF的占空比可变，并基于所述相位信息而使所述开关单元ON，在固定时间后使开关单元OFF，由此进行电力控制。The 13th embodiment of the present invention is based on any one of the 8th to 12th embodiments, wherein the driving circuit includes a switching unit that drives the primary coil, the switching unit makes the ON-OFF duty cycle variable, and turns on the switching unit based on the phase information, and turns off the switching unit after a fixed time, thereby performing power control.
本发明的第14实施例是根据第8实施例或第11实施例，其中所述谐振电流相位检测单元根据流入至并联连接于所述谐振电容器的小电容电容器的电流来检测所述相位信息。A fourteenth embodiment of the present invention is based on the eighth embodiment or the eleventh embodiment, wherein the resonant current phase detection unit detects the phase information based on a current flowing into a small capacitance capacitor connected in parallel to the resonant capacitor.
[发明效果][Effects of the Invention]
本发明中，在一次线圈中未设置谐振电路可得到更好的结果。若谐振电容器仅耦合于二次线圈而设置谐振电路，谐振电流不会流入至一次线圈，因而可抑制一次线圈中的发热。然而，例如将可变电容器等的技术进行并用等，而利用一次侧谐振是任意的。In the present invention, better results are achieved by omitting a resonant circuit in the primary coil. If a resonant capacitor is coupled only to the secondary coil and a resonant circuit is provided, resonant current does not flow into the primary coil, thereby suppressing heat generation in the primary coil. However, utilizing primary-side resonance is optional, for example, by combining technologies such as variable capacitors.
另外，由于不受一次线圈的谐振频率限制，因此可自动选择自一次线圈侧观察到的功率因素最佳的频率作为驱动频率，故而可大幅提升稳固性。Furthermore, since the drive frequency is not restricted by the resonant frequency of the primary coil, the frequency with the best power factor observed from the primary coil side can be automatically selected as the drive frequency, significantly improving stability.
进而，本发明中始终维持ZVS动作，因此可采用半桥接(half bridge)的电路构成作为驱动电路，与现有的无线电力传送装置相比可通过简单的电路构成实现装置。Furthermore, in the present invention, ZVS operation is always maintained, so a half-bridge circuit configuration can be adopted as a driving circuit, and the device can be realized with a simpler circuit configuration than conventional wireless power transmission devices.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1是表示本发明的无线电力传送装置的主要部分的构成的方块图。FIG. 1 is a block diagram showing the configuration of a main part of a wireless power transmission device according to the present invention.
图2A、图2B是表示本发明所使用的开关单元的一例的电路图。2A and 2B are circuit diagrams showing an example of a switching unit used in the present invention.
图3是表示包含本发明的谐振电流相位检测单元的检测部的构成的图。FIG3 is a diagram showing the configuration of a detection unit including a resonant current phase detection unit according to the present invention.
图4是表示本发明的谐振电流相位检测单元的另一例的图。FIG4 is a diagram showing another example of the resonant current phase detection unit according to the present invention.
图5A、图5B、图5C是表示本发明的谐振电流相位检测单元又一例的图。5A, 5B, and 5C are diagrams showing still another example of the resonant current phase detection unit of the present invention.
图6是对因谐振电流相位波形中所含的失真而扰乱相位信息的情况进行说明的图。FIG. 6 is a diagram explaining how phase information is disturbed by distortion included in the resonant current phase waveform.
图7是表示自谐振电流相位波形中去除高次谐波失真的概念图。FIG. 7 is a conceptual diagram showing the removal of harmonic distortion from a self-resonant current phase waveform.
图8是表示谐振电流相位信息中产生相位延迟的情况下的各种波形的变化的概念图。FIG. 8 is a conceptual diagram showing changes in various waveforms when a phase delay occurs in the resonant current phase information.
图9是表示谐振电流相位信息的相位延迟小的情况下流入至正进行ZVS动作的开关单元的电流的波形的图。FIG. 9 is a diagram showing a waveform of a current flowing into a switching unit performing a ZVS operation when a phase delay of resonant current phase information is small.
图10是表示谐振电流相位信息的相位延迟大的情况下流入至未进行ZVS动作的开关单元的电流的波形的图。FIG. 10 is a diagram showing a waveform of a current flowing into a switching unit that is not performing a ZVS operation when a phase delay of resonant current phase information is large.
图11是表示对谐振电流相位信息的相位进行修正的电路的一例的图。FIG. 11 is a diagram showing an example of a circuit for correcting the phase of resonant current phase information.
图12A、图12B是对相位信息的修正进行说明的图。12A and 12B are diagrams for explaining correction of phase information.
图13是进行相位修正的情况下的具体电路图。FIG13 is a specific circuit diagram when phase correction is performed.
图14是进行相位修正的情况下的另一具体电路图。FIG14 is another specific circuit diagram when phase correction is performed.
图15是进行相位修正的情况下的又一具体电路图。FIG15 is another specific circuit diagram when phase correction is performed.
图16是对谐振电容器的电流相位与一次线圈的电流相位的关系进行说明的图。FIG. 16 is a diagram illustrating the relationship between the current phase of the resonant capacitor and the current phase of the primary coil.
图17是求出用以获得功率因素1的所需最小Q值的图。FIG. 17 is a graph showing how to find the minimum Q value required to achieve a power factor of 1.
图18是最小所需的Q值伴随k的降低而逐渐接近k2Q＝2的情况的说明图。FIG. 18 is an explanatory diagram showing a case where the minimum required Q value gradually approaches k2 Q=2 as k decreases.
图19是表示在设为Q＝2/k2的情况下一次线圈的电流相位曲线横穿0度的情况的图。FIG. 19 is a diagram showing a case where the current phase curve of the primary coil crosses 0 degrees when Q=2/k2. FIG.
图20是对本发明的电力控制的一例进行说明的图。FIG. 20 is a diagram illustrating an example of power control according to the present invention.
图21是对本发明的电力控制的另一例进行说明的图。FIG. 21 is a diagram illustrating another example of power control according to the present invention.
图22是对进行本发明的电力控制的情况下的与一次线圈的电流相位的关系进行说明的图。FIG. 22 is a diagram illustrating the relationship between the current phase of the primary coil and the current phase when the power control according to the present invention is performed.
图23是表示可保持与Qi(气)规格的相容性并进行效率改善的电路的一例的图。FIG. 23 is a diagram showing an example of a circuit that can improve efficiency while maintaining compatibility with the Qi standard.
图24是表示现有的磁场谐振方式的无线电力传送装置的构成的方块图。FIG. 24 is a block diagram showing the configuration of a conventional magnetic field resonance type wireless power transmission device.
图25是现有的磁场谐振方式的无线电力传送装置的等效电路图。FIG. 25 is an equivalent circuit diagram of a conventional magnetic field resonance type wireless power transmission device.
附图标号说明：Description of Figure Numbers:
100：无线电力传送装置；100: wireless power transmission device;
110：一次线圈；110: primary coil;
120：驱动电路；120: driving circuit;
122：驱动单元；122: drive unit;
124：开关单元；124: switch unit;
140：二次线圈；140: Secondary coil;
150：谐振电容器；150: resonant capacitor;
155：小电容电容器；155: small capacitance capacitor;
160：谐振电流相位检测单元；160: resonant current phase detection unit;
165：滤波器；165: filter;
170：相位信息传递单元；170: phase information transmission unit;
190：第三线圈。190: The third coil.
具体实施方式DETAILED DESCRIPTION
以下，参照附图，对本发明的无线电力传送装置的实施例进行详细说明。Hereinafter, embodiments of the wireless power transmission device of the present invention will be described in detail with reference to the accompanying drawings.
图1是表示本发明的无线电力传送装置100的一实施例的主要部分的构成的方块图。FIG. 1 is a block diagram showing the configuration of the main parts of a wireless power transmission device 100 according to an embodiment of the present invention.
一次侧包含一次线圈(Primary coil)110及通过电容器Cc而与一次线圈连接的驱动电路120，驱动电路120包含驱动单元(Driving means)122、及开关单元(Switchingmeans)124。另外，开关单元124构成为包含晶体管元件Q1～晶体管元件Q4的桥接(bridge)电路。The primary side includes a primary coil 110 and a drive circuit 120 connected to the primary coil via a capacitor Cc. Drive circuit 120 includes a driving means 122 and a switching means 124. Switching means 124 is configured as a bridge circuit including transistor elements Q1 to Q4.
二次侧包含与一次线圈110以耦合系数k加以隔离而配置的二次线圈(Secondarycoil)140、耦合于所述二次线圈140而构成谐振电路的谐振电容器(Cp)150、及对流入至所述谐振电容器(Cp)150的谐振电流的相位信息进行检测的谐振电流相位检测单元(Resonance current phase detection means)160。在本发明中，包括相位信息传递单元170，所述相位信息传递单元170将由谐振电流相位检测单元160检测到的相位信息无相位延迟地传递至驱动电路120，且驱动电路120基于所述相位信息规定驱动频率而驱动一次线圈110。相位信息传递单元170包含相位信息发送单元(Phase information Transmitter)172及相位信息接收单元(Phase information Receiver)174。The secondary side includes a secondary coil 140, isolated from the primary coil 110 by a coupling coefficient k; a resonant capacitor (Cp) 150 coupled to the secondary coil 140 to form a resonant circuit; and a resonant current phase detection unit 160 that detects the phase information of the resonant current flowing into the resonant capacitor (Cp) 150. In the present invention, a phase information transmission unit 170 is included. This phase information transmission unit 170 transmits the phase information detected by the resonant current phase detection unit 160 to the drive circuit 120 without phase delay. The drive circuit 120 drives the primary coil 110 at a predetermined driving frequency based on the phase information. Phase information transmission unit 170 includes a phase information transmitter 172 and a phase information receiver 174.
另外，二次侧连接于未图示的负载。In addition, the secondary side is connected to a load (not shown).
在本发明中，仅就谐振电路而言，以谐振电容器(Cp)150耦合于二次线圈140而构成的谐振电路为本质，即便未在一次线圈110设置串联谐振电容器亦可进行效率足够好的电力传送。In the present invention, the resonant circuit is essentially a resonant circuit formed by coupling the resonant capacitor (Cp) 150 to the secondary coil 140 , and even without providing a series resonant capacitor in the primary coil 110 , power transmission with sufficient efficiency can be achieved.
图1所示的电容器Cc仅仅是为了阻断直流而设置，并非作为谐振电容器设置。The capacitor Cc shown in FIG1 is provided only for blocking direct current and is not provided as a resonant capacitor.
更详细而言，虽然亦可作为改良方法而对本发明设置一次侧谐振，但其于本发明中为任意且为非本质。More specifically, although the primary-side resonance can be provided to the present invention as an improvement method, it is arbitrary and non-essential to the present invention.
另外，只要可精密地控制开关单元124的驱动时序(timing)，而可保持流入至各晶体管元件Q1～晶体管元件Q4的电流的平衡(balance)，则也可省略电容器Cc。Furthermore, the capacitor Cc may be omitted as long as the driving timing of the switch unit 124 can be precisely controlled to maintain a balance between the currents flowing into the transistor elements Q1 to Q4 .
在本发明中，通过谐振电流相位检测单元160对流入至谐振电路的谐振电流的相位信息进行检测，所述谐振电路包含二次线圈140及与所述二次线圈并联或串联地连接的谐振电容器(Cp)150，并将所述相位信息自位于二次侧的相位信息发送单元172发送至位于一次侧的相位信息接收单元174，从而基于所述相位信息来决定驱动单元122的驱动时序。In the present invention, the phase information of the resonant current flowing into the resonant circuit is detected by the resonant current phase detection unit 160. The resonant circuit includes a secondary coil 140 and a resonant capacitor (Cp) 150 connected in parallel or series with the secondary coil. The phase information is transmitted from the phase information transmitting unit 172 on the secondary side to the phase information receiving unit 174 on the primary side, thereby determining the driving timing of the driving unit 122 based on the phase information.
在本发明中，由于设为一次侧未设置谐振电路的构成，故一次线圈110的圈数与现有的需要一次侧谐振电路的磁场谐振方式相比而圈数不同。In the present invention, since no resonant circuit is provided on the primary side, the number of turns of the primary coil 110 is different from that of the conventional magnetic field resonance method which requires a resonant circuit on the primary side.
另外，相位信息传递单元170“无相位延迟地”传递通过谐振电流相位检测单元160而检测到的相位信息，但所有检测单元或传递单元必然存在相位延迟，因此，此处“无相位延迟地”意为，使相位延迟尽可能小，目的在于使一次侧驱动单元与二次侧共有绝对时间即可。In addition, the phase information transmission unit 170 transmits the phase information detected by the resonant current phase detection unit 160 "without phase delay." However, all detection units or transmission units inevitably have phase delay. Therefore, "without phase delay" here means making the phase delay as small as possible, with the goal of ensuring that the primary-side drive unit and the secondary-side share absolute time.
其次，对图1的方块图所示的各构成要素进行说明。Next, each component shown in the block diagram of FIG1 will be described.
驱动单元122基于自相位信息传递单元170传递的相位信息，以使流入至一次线圈110的驱动电流的电流相位较施加于一次线圈110的驱动电压的电压相位略微延迟的方式来决定驱动频率，从而驱动开关单元124。关于其详细动作将在下文进行叙述。Based on the phase information transmitted from the phase information transmitting unit 170, the driving unit 122 determines the driving frequency so that the current phase of the driving current flowing into the primary coil 110 is slightly delayed relative to the voltage phase of the driving voltage applied to the primary coil 110, thereby driving the switching unit 124. The detailed operation will be described below.
开关单元124包含两个或四个晶体管等开关元件(Q1～Q4)，通过直流阻断电容器Cc来驱动一次线圈110。The switching unit 124 includes two or four switching elements ( Q1 - Q4 ) such as transistors, and drives the primary coil 110 via the DC blocking capacitor Cc.
图2A、图2B是表示开关单元124的一例的电路图，A表示全桥接(full bridge)电路，B表示半桥接电路。在本发明中，开关单元124可包含全桥接电路也可包含半桥接电路。2A and 2B are circuit diagrams showing an example of the switch unit 124. A represents a full bridge circuit, and B represents a half bridge circuit. In the present invention, the switch unit 124 may include a full bridge circuit or a half bridge circuit.
在现有的无线电力传送中，自开关单元124侧观察到的施加于一次线圈110的驱动电压、与流入至一次线圈110的驱动电流的相位关系会根据驱动频率而大幅变化，因此难以在各种条件下保持ZVS而防止硬开关(hard switching)。因此，出于即便发生硬开关也不易产生异常电压的理由，优选采用全桥接电路。In conventional wireless power transmission, the phase relationship between the drive voltage applied to the primary coil 110 and the drive current flowing into the primary coil 110, as viewed from the switching unit 124, varies significantly depending on the drive frequency. This makes it difficult to maintain ZVS under various conditions and prevent hard switching. Therefore, a full-bridge circuit is preferred because it is less likely to generate abnormal voltages even when hard switching occurs.
在本发明中，可放心采用以往认为会发生硬开关而欠佳的半桥接电路。原因在于，在本发明中，可在各种条件下保持ZVS。详细情况将在下文进行叙述。但，全桥接电路仅具有电源的利用效率高的优点，在本发明中并非必需条件，因此以下用使用全桥接电路作为开关单元124的情况来进行说明。The present invention allows for the safe use of a half-bridge circuit, previously considered undesirable due to hard switching. This is because it maintains ZVS under various conditions. Details will be described below. However, a full-bridge circuit only offers the advantage of high power efficiency and is not a prerequisite for the present invention. Therefore, the following description uses a full-bridge circuit as the switching element 124.
图3是表示包含本发明的谐振电流相位检测单元160的检测部的构成的图。FIG3 is a diagram showing the configuration of a detection unit including the resonant current phase detection means 160 according to the present invention.
在二次线圈140并联连接有谐振电容器(Cp)150及小电容的电容器(Cps)155。A resonant capacitor (Cp) 150 and a small-capacitance capacitor (Cps) 155 are connected in parallel to secondary coil 140 .
谐振电流检测单元160可如图1所示，为直接对流入至谐振电容器(Cp)150的电流的相位信息进行检测者，也可如图3所示，为对流入至并联连接的小电容电容器(Cps)155的电流的相位信息进行检测者(160a)。原因在于，施加于谐振电容器(Cp)150的电压、与施加于与其并联连接的小电容电容器(Cps)155电压均为相同，因此流入至各电容器的电流的相位信息也相同。在多数情况下，流入至谐振电容器(Cp)150的电流非常大，因此若欲直接检测所述电流，则谐振电流检测单元160需要包含大电容的零件，但若对流入至小电容电容器(Cps)的电流进行检测，则可包含小电容的零件。The resonant current detection unit 160 can be a unit that directly detects the phase information of the current flowing into the resonant capacitor (Cp) 150, as shown in FIG1 , or can be a unit (160a) that detects the phase information of the current flowing into the small-capacitance capacitor (Cps) 155 connected in parallel, as shown in FIG3 . The reason is that the voltage applied to the resonant capacitor (Cp) 150 and the voltage applied to the small-capacitance capacitor (Cps) 155 connected in parallel are the same, so the phase information of the current flowing into each capacitor is also the same. In most cases, the current flowing into the resonant capacitor (Cp) 150 is very large, so if the current is to be detected directly, the resonant current detection unit 160 needs to include a component with a large capacitor, but if the current flowing into the small-capacitance capacitor (Cps) is to be detected, it can include a component with a small capacitor.
由谐振电流相位检测单元160检测到的谐振电流的相位信息利用谐振电流相位传递单元170而传递至一次侧的驱动电路120。The phase information of the resonant current detected by the resonant current phase detection unit 160 is transmitted to the primary-side driving circuit 120 by the resonant current phase transmission unit 170 .
就谐振电流相位传递单元170的构成而言，可考虑各种，可为使用发光二极管(Light Emitting Diode，LED)与光电晶体管(phototransistor)的光耦合，可利用将相位信息数字化(digital)所得的信号对磁电路进行调变而进行传递，也可为使用高频载波(carrier)的电磁波的无线方法。但，在使用光电晶体管作为受光部的情况下因存储电荷导致的延迟大，使光电晶体管饱和而使用的方法欠佳。因此，光电晶体管优选为非饱和动作，进而，更优选为用以抑制镜像(mirror)效应的定电压动作。另外，更优选为使用PIN光电二极管(PIN photodiode)，或进而将其以反向偏压(bias)使用而实现高速动作等。Various configurations are possible for the resonant current phase transmission unit 170. These include optical coupling using a light emitting diode (LED) and a phototransistor, modulation of a magnetic circuit using a signal obtained by digitizing phase information, and wireless transmission using electromagnetic waves from a high-frequency carrier. However, when using a phototransistor as a light-receiving element, the delay caused by stored charge is large, leading to saturation of the phototransistor, which is not optimal. Therefore, the phototransistor is preferably operated in a non-saturated state, and more preferably, in a constant voltage state to suppress the mirror effect. Furthermore, it is more preferable to use a PIN photodiode, or to use it with a reverse bias to achieve high-speed operation.
另外，谐振电流相位检测单元160也可如图4所示，为对流入至二次线圈140的电流进行检测者(160b)。但，在所述情况下，检测到的相位信息中还包含并合成有流入至负载的电流的相位成分。流入至负载的电流的相位成分较谐振电流相位延迟90°，因此合成有这些矢量(vector)而相位信息会产生若干相位延迟。若基于所述相位信息来驱动一次线圈110则并非进行ZVS动作，容易产生硬开关。Alternatively, as shown in Figure 4 , the resonant current phase detection unit 160 can also be configured to detect the current flowing into the secondary coil 140 (160b). However, in this case, the detected phase information also includes and synthesizes the phase component of the current flowing into the load. The phase component of the current flowing into the load is 90° behind the resonant current, so the synthesis of these vectors results in a slight phase delay in the phase information. Driving the primary coil 110 based on this phase information does not achieve ZVS operation, and hard switching is likely to occur.
若产生硬开关，则会在开关单元124的元件(Q1～Q4)产生高频的寄生振动，在所述情况下，电磁干扰(Electro-Magnetic Interference，EMI)、尤其是噪声电力/噪声电场强度(辐射)变多。因此需要加以对策，关于此将在下文进行叙述。If hard switching occurs, high-frequency parasitic vibrations are generated in the elements (Q1-Q4) of switch unit 124. This increases electromagnetic interference (EMI), particularly noise power and noise electric field intensity (radiation). Therefore, countermeasures are necessary, as described below.
谐振电流相位检测单元160也可如图5A、图5B、图5C所示，为对流入至一次线圈110的电流进行检测者(160c)。图5A表示自二次线圈140将电力提取至负载R的类型(type)，图5B表示在二次线圈中包含作为自耦变压器的第三线圈190，自第三线圈190将电力提取至负载R的类型，图5C表示自与二次线圈140接近且作为独立的线圈而设置的第三线圈190将电力提取至负载R的类型。另外，关于在二次侧设置有第三线圈190的图5B、图5C的类型的详细情况将在下文进行叙述。这些情况下大多会产生硬开关，因此需要另外进行相位修正，关于此将在下文进行叙述。As shown in Figures 5A, 5B, and 5C, the resonant current phase detection unit 160 may also be a unit (160c) that detects the current flowing into the primary coil 110. Figure 5A illustrates a type in which power is extracted from the secondary coil 140 to a load R. Figure 5B illustrates a type in which power is extracted from the third coil 190 to the load R, including a third coil 190 serving as an autotransformer within the secondary coil. Figure 5C illustrates a type in which power is extracted from the third coil 190, provided as an independent coil adjacent to the secondary coil 140. Details of the types shown in Figures 5B and 5C, in which the third coil 190 is provided on the secondary side, will be described below. In most cases, hard switching occurs, requiring additional phase correction, which will be described below.
另外，有时会在作为谐振电流相位信息的延迟的原因而被检测到的谐振电流中产生失真。所述失真会扰乱谐振电流相位信息，一次线圈110的驱动时序变得不准确，结果无法准确检测出谐振频率的峰值(peak)。Furthermore, the detected resonant current may be distorted due to a delay in the resonant current phase information, which may disrupt the resonant current phase information and cause inaccurate driving timing of the primary coil 110, resulting in an inability to accurately detect the peak of the resonant frequency.
图6是谐振电流中包含三次高频的情况下的示例，是对因所述失真而扰乱相位信息的情况进行说明的说明图。在此种情况下，利用适当的滤波器单元而仅提取基本成分来作为谐振电流相位信息，由此可提升相位信息的精度。另外，也可不使用滤波器，将谐振电流数字地级数展开而仅使用基谐波的相位信息。Figure 6 shows an example where the resonant current contains a third-order high frequency component, illustrating how this distortion disrupts phase information. In this case, using an appropriate filter unit to extract only the fundamental component as resonant current phase information improves phase information accuracy. Alternatively, the resonant current can be digitally expanded without using a filter, using only the phase information of the fundamental harmonic.
图7是表示在谐振电流相位检测单元160设置仅提取基谐波的滤波器(基本波形滤波器(Fundamental waveform filter))165而自谐振电流相位波形中去除高次谐波失真的概念图。FIG7 is a conceptual diagram showing that a filter (fundamental waveform filter) 165 that extracts only the fundamental harmonic is provided in the resonant current phase detection unit 160 to remove harmonic distortion from the resonant current phase waveform.
其次，对本发明中重要的二次侧谐振电路的Q值的设定进行说明。Next, the setting of the Q value of the secondary-side resonant circuit, which is important in the present invention, will be described.
无线电力传送与一般的利用漏磁变压器(leakage transformer)的供电大不相同。在利用漏磁变压器进行供电的情况下，一次线圈与二次线圈之间的耦合系数(k)在所有驱动条件下大致为固定，与此相对，在无线电力传送中，耦合系数(k)大幅变化。在现有的利用漏磁变压器的供电中，二次侧谐振电路的Q值无需那么高。Wireless power transmission differs significantly from conventional power supply using a leakage transformer. While the coupling coefficient (k) between the primary and secondary coils remains roughly constant under all driving conditions, the coupling coefficient (k) varies significantly in wireless power transmission. Conventional power supply using a leakage transformer does not require a high Q value for the secondary resonant circuit.
另一方面，在无线电力传送的情况下，由于耦合系数(k)变化，故在耦合系数(k)小的情况下需要高Q值。On the other hand, in the case of wireless power transmission, since the coupling coefficient (k) varies, a high Q value is required when the coupling coefficient (k) is small.
原因在于：在Q值低的情况、使用的条件大幅变化的情况下，难以良好地维持一次线圈的功率因素，且在若Q值过高则使用的条件仍大幅变化的情况下，难以满足如下条件(即ZVS动作条件)：以使流入至一次线圈的驱动电流的电流相位较施加于一次线圈的驱动电压的电压相位略微延迟的方式规定驱动频率而驱动一次线圈。The reason is that when the Q value is low and the operating conditions vary significantly, it is difficult to maintain the power factor of the primary coil well. If the Q value is too high and the operating conditions still vary significantly, it is difficult to meet the following conditions (i.e., ZVS operation conditions): the primary coil is driven by specifying the driving frequency in such a way that the current phase of the driving current flowing into the primary coil is slightly delayed compared to the voltage phase of the driving voltage applied to the primary coil.
在本发明中，在欲提升稳固性的情况下需要高Q值。然而，Q值越高则半宽度会变得非常窄，微小的频率混乱便成为问题。因此，需要使谐振电流相位信息的传送单元中的相位延迟(或时间的延迟)尽量变小。若谐振电流相位信息的传递单元中产生延迟，则会发生如下情况。In the present invention, a high Q value is required to improve robustness. However, a higher Q value leads to a significantly narrower half-width, causing minor frequency disturbances to become problematic. Therefore, it is necessary to minimize the phase delay (or time delay) in the transmission unit of the resonant current phase information. If a delay occurs in the transmission unit of the resonant current phase information, the following problems may occur.
图8是表示在谐振电流相位信息产生相位延迟的情况下的各种波形的变化的概念图。FIG. 8 is a conceptual diagram showing changes in various waveforms when a phase delay occurs in the resonant current phase information.
a是谐振电路的谐振电流的波形，b是由谐振电流相位检测单元160检测到的相位信息的波形，c是自相位信息接收单元174输出的相位信息的波形，d是流过一次线圈11的电流的电流波形。自相位信息接收单元174输出的波形c较波形b延迟，几乎保持原样成为开关单元124的驱动波形。a is the waveform of the resonant current in the resonant circuit, b is the waveform of the phase information detected by resonant current phase detection section 160, c is the waveform of the phase information output from phase information receiving section 174, and d is the current waveform of the current flowing through primary coil 11. Waveform c output from phase information receiving section 174 is delayed compared to waveform b and remains substantially unchanged as the driving waveform for switch section 124.
图9是表示在谐振电流相位信息的相位延迟小的情况下流入至正进行ZVS动作的情况下的开关单元124的电流的波形的图。FIG. 9 is a diagram showing a waveform of a current flowing into the switching unit 124 when a phase delay of the resonant current phase information is small and the ZVS operation is being performed.
在相位信息接收单元174的波形不存在延迟的情况下、或极小的情况下(c)，与开关单元124的开关时序相比，流入至一次线圈110的电流的时序稍微提前(d)，因此开关单元124的开关元件Q1、开关元件Q2的电流波形(e、f)成为ZVS动作。所述情况下，开关单元124的中心分接(center tap)电压成为整齐的方形波(g)。When the waveform of phase information receiving unit 174 exhibits no delay or minimal delay (c), the timing of the current flowing into primary coil 110 is slightly advanced compared to the switching timing of switch unit 124 (d). Consequently, the current waveforms (e, f) of switching elements Q1 and Q2 of switch unit 124 exhibit ZVS operation. In this case, the center tap voltage of switch unit 124 forms a neat square wave (g).
与此相对，图10是表示谐振电流相位信息的相位延迟大的情况下流入至未进行ZVS动作时的开关单元124的电流的波形的图。In contrast, FIG. 10 is a diagram showing a waveform of a current flowing into the switching unit 124 when the ZVS operation is not performed, when the phase delay of the resonant current phase information is large.
与开关单元124的开关时序相比，流入至一次线圈110的电流的时序变迟(d)，因此开关元件Q1、开关元件Q2的电流波形(e、f)未成为ZVS动作，在开关单元124的中心分接电压产生回跳(rebound)引起的特有的脉冲(pulse)波形(g)。若产生所述回跳波形则还可能破坏开关元件Q1、开关元件Q2或驱动单元122，或者成为产生EMI的原因。Compared to the switching timing of switching element 124, the timing of the current flowing into primary coil 110 is delayed (d). As a result, the current waveforms (e, f) of switching elements Q1 and Q2 do not achieve ZVS operation. Instead, a unique pulse waveform (g) is generated due to rebound in the center tap voltage of switching element 124. This rebound waveform may damage switching element Q1, switching element Q2, or driver unit 122, or may cause EMI.
根据以上，在本发明中，需要使相位信息传递单元170中的相位延迟尽可能小。在无法避免相位延迟的情况下，使用如下的相位修正单元。Based on the above, in the present invention, it is necessary to minimize the phase delay in the phase information transmitting unit 170. If the phase delay cannot be avoided, the following phase correction unit is used.
图11是表示对谐振电流相位信息的相位进行修正的电路的一例的图。FIG. 11 is a diagram showing an example of a circuit for correcting the phase of resonant current phase information.
在谐振电流相位检测单元160内设置：谐振电流波形检测电路162；反转积分电路164，将检测到的谐振电流的波形反转后进行积分或积分后进行反转；以及加法运算电路166，将来自谐振电流波形检测电路162的输出与来自反转积分电路164的输出加以重叠合成。进行反转积分所得的波形较原本的谐振电流的波形相位前进90度。由此，可通过基于如下的波形来检测谐振电流的相位信息，而获得在相位前进的方向上得到修正的谐振电流相位信息，所述波形是以适当的比率将原本的谐振电流的波形、及将其反转并积分所得的波形加以重叠合成所得。然后，将所述谐振电流相位信息通过相位信息传递单元170而发送至相位信息接收单元174。The resonant current phase detection unit 160 includes a resonant current waveform detection circuit 162; an inverting integration circuit 164 that inverts and integrates the detected resonant current waveform, or integrates and then inverts it; and an adding circuit 166 that superimposes the output of the resonant current waveform detection circuit 162 with the output of the inverting integration circuit 164. The waveform obtained by the inverting integration is phase-shifted by 90 degrees relative to the original resonant current waveform. Thus, by detecting resonant current phase information based on a waveform obtained by superimposing the original resonant current waveform and the waveform obtained by inverting and integrating it at an appropriate ratio, resonant current phase information corrected in the direction of phase shift can be obtained. This resonant current phase information is then transmitted to the phase information receiving unit 174 via the phase information transmission unit 170.
图12A、图12B是对所述相位信息的修正进行说明的图。12A and 12B are diagrams for explaining the correction of the phase information.
a是原本的谐振电流波形信息，b是将其反转积分所得者。c是将a与b加以重叠合成所得的合成波形。由此，在相位前进的方向上得到修正的相位信息d成为无延迟地传递原本的谐振电流波形信息a的波形。a represents the original resonant current waveform information, b represents its inverse integration, and c represents the composite waveform obtained by superimposing a and b. Thus, phase information d, corrected in the direction of phase advancement, becomes a waveform that transmits the original resonant current waveform information a without delay.
另外，反转积分电路164也可使用运算放大器(operational amplifier)而构成，也可构成为在使用变压器进行反转后，使用电容器(C)与电阻(R)进行积分。Alternatively, the inverting integration circuit 164 may be configured using an operational amplifier, or may be configured to perform inversion using a transformer and then perform integration using a capacitor (C) and a resistor (R).
图13是表示进行相位修正的情况下的谐振电流相位检测单元160a的具体电路图的图。FIG13 is a diagram showing a specific circuit diagram of the resonant current phase detection unit 160a when performing phase correction.
谐振电流波形信息a通过缓冲放大器(buffer amplifier)并通过反转积分电路164进行反转积分，由合成电路166进行合成，由此获得相位前进、并进行过修正的波形c(参照图12A)。The resonant current waveform information a passes through a buffer amplifier and is inversely integrated by an inverting integration circuit 164 , and then synthesized by a synthesizing circuit 166 , thereby obtaining a phase-advanced and corrected waveform c (see FIG. 12A ).
图14是表示谐振电流相位检测单元160b另一具体电路图的图，着眼于谐振电容器Cp150的两端电压相对于谐振电流波形成为积分波形的情况，将其适当分压并反转而进行相位修正。FIG14 is another specific circuit diagram of the resonant current phase detection unit 160b, which focuses on the fact that the voltage across the resonant capacitor Cp150 becomes an integrated waveform with respect to the resonant current waveform, and appropriately divides and inverts it to perform phase correction.
谐振电流波形信息a通过合成电路166而与经反转的谐振电容器电压合成，由此获得相位前进、进行过修正的波形c(参照图12B)。The resonant current waveform information a is combined with the inverted resonant capacitor voltage by the combining circuit 166, thereby obtaining a waveform c (see FIG12B) whose phase is advanced and corrected.
图15是表示谐振电流相位检测单元160c的又一具体电路图的图。在所述例中，将自一次线圈110通过电流变压器167而检测到的谐振电流波形与其反转积分波形加以合成而进行相位修正。在一次侧检测到的谐振电流相位波形为a，经反转积分的谐振电流相位波形为b，通过将这些加以合成而获得进行过修正的波形c。FIG15 shows another specific circuit diagram of resonant current phase detection section 160c. In this example, the resonant current waveform detected from primary coil 110 via current transformer 167 is combined with its inverted integrated waveform to perform phase correction. The resonant current phase waveform detected on the primary side is represented by a, and the inverted integrated resonant current phase waveform is represented by b. These waveforms are combined to produce the corrected waveform c.
另外，也可不进行反转，使用微分波形而非积分，其作为本发明中的适当的设计事项包含于反转积分的含义中。然而，在微分波形中，多数情况下，加强并重叠有高次谐波成分，因此与使用积分波形的情况相比无法称为优选。另外，相位的修正单元可进而将160a、160b、160c各自的谐振电流相位波形a与其反转积分波形b适当单独组合，也可替换电流检测单元160a、电流检测单元160b各自的电路。Alternatively, it is possible to use a differential waveform instead of an integral waveform without inversion. This is a suitable design consideration within the meaning of inversion integration in the present invention. However, differential waveforms often have higher harmonic components that are emphasized and superimposed, making this less preferable than using an integral waveform. Furthermore, the phase correction unit can further combine the resonant current phase waveform a of each of 160a, 160b, and 160c with its inverted integral waveform b as appropriate, or replace the circuits of each of current detection units 160a and 160b.
所述中，对模拟地处理谐振电流波形信息或谐振电流相位信息的情况进行了说明，但对于本发明中的相位的传递单元而言，目的在于使一次侧驱动单元与二次侧共有绝对时间，本发明中的相位修正单元只要以包含谐振电流相位信息的波形为基础，结果获得相位前进的修正波形即可。While the above description describes the case of analog processing of resonant current waveform information or resonant current phase information, the phase transfer unit of the present invention is intended to enable the primary-side drive unit and the secondary-side drive unit to share absolute time. The phase correction unit of the present invention only needs to use the waveform containing the resonant current phase information as a basis to obtain a corrected waveform with an advanced phase.
另外，若可通过某种方法获得绝对时间的共有，则也可根据与所述绝对时间的差获得经修正的相位信息从而获得经修正的相位波形。即，毋庸置疑可基于这些见解而数字地进行处理。Furthermore, if the absolute time can be shared by some method, the corrected phase information can be obtained from the difference from the absolute time, thereby obtaining a corrected phase waveform. In other words, it is obvious that digital processing can be performed based on these insights.
其次，对本发明中重要的在二次侧构成的谐振电路的Q值的设定进行说明。Next, the setting of the Q value of the resonant circuit configured on the secondary side, which is important in the present invention, will be described.
如上所述，在无线电力传送的情况下，由于耦合系数(k)发生变化，故在耦合系数(k)低的情况下，谐振电路中尤其需要大Q值。在Q值低的情况、使用的条件大幅变化的情况下，难以满足如流入至一次线圈的驱动电流的电流相位较施加于一次线圈的驱动电压的电压相位略微延迟的条件而驱动一次线圈。As mentioned above, in wireless power transmission, the coupling coefficient (k) varies. Therefore, when the coupling coefficient (k) is low, a high Q value is particularly required in the resonant circuit. With a low Q value or when operating conditions vary significantly, it becomes difficult to drive the primary coil while maintaining a slightly delayed phase between the drive current flowing into the primary coil and the voltage applied to the primary coil.
为了解决所述问题，驱动频率不宜为固定(也称为所谓固定频率方式或他励(separate excitation)方式)，需要基于流入至二次侧的谐振电路的谐振电容器的谐振电流、流入至二次线圈的谐振电流、或反映于一次线圈的谐振电流的相位信息来控制驱动电路。其结果为，不得不使驱动频率可变。在磁场谐振方式的无线电力传送中，根据负载的电阻成分使驱动频率变化已记载于专利文献1中。To address this issue, a fixed drive frequency is not recommended (also known as a fixed-frequency method or separate excitation method). Instead, the drive circuit must be controlled based on the phase information of the resonant current flowing into the resonant capacitor of the secondary-side resonant circuit, the resonant current flowing into the secondary coil, or the resonant current reflected in the primary coil. Consequently, the drive frequency must be variable. Patent Document 1 describes varying the drive frequency based on the load's resistance in magnetic field resonance wireless power transmission.
在专利文献1中记载的发明中，利用通过进行负载电阻的检测而预先程序化的预测信息或计算、及可饱和电感器(Inductor)而获得最佳的驱动频率，从而对驱动单元进行驱动。然而，所述方法中，仅自驱动一次线圈的驱动电路的开关单元观察到的功率因素接近1，而自一次线圈观察到的功率因素并不接近1，因此虽可抑制开关单元的发热但自一次线圈侧观察到的功率因素非常差，成为一次线圈发热的原因。The invention described in Patent Document 1 uses pre-programmed prediction information or calculations based on load resistance detection and a saturable inductor to achieve an optimal drive frequency, thereby driving the drive unit. However, in this method, only the power factor observed by the switch unit of the drive circuit driving the primary coil is close to 1, while the power factor observed by the primary coil is not close to 1. Therefore, while heating of the switch unit can be suppressed, the power factor observed by the primary coil is extremely poor, causing heating of the primary coil.
在本发明中，为了排除一次线圈侧的谐振电路，导出用以使自一次线圈观察到的功率因素接近1的条件，而将二次线圈侧的谐振电路的Q值设定得较通常更高。In the present invention, in order to eliminate the resonant circuit on the primary coil side and derive a condition for making the power factor observed from the primary coil close to 1, the Q value of the resonant circuit on the secondary coil side is set higher than usual.
图16是对耦合于二次线圈的谐振电容器的电流相位与一次线圈的电流相位的关系进行说明的图，是通过仿真(simulation)求出使耦合系数(k)变化的情况下所必需的Q值的图。FIG. 16 is a diagram illustrating the relationship between the current phase of the resonant capacitor coupled to the secondary coil and the current phase of the primary coil, and is a diagram showing the Q value required when the coupling coefficient (k) is changed by simulation.
a是一次线圈的电流相位，纵轴是相位角，横轴是驱动频率。b是二次侧谐振电容器的电流相位，纵轴是相位角，横轴是驱动频率。c是传递比，纵轴是传递比，横轴是驱动频率。就传递比而言，若将其乘以一次线圈的圈数与二次线圈的圈数的比则大致成为升压比。a represents the current phase of the primary coil, with the vertical axis representing the phase angle and the horizontal axis representing the drive frequency. b represents the current phase of the secondary resonant capacitor, with the vertical axis representing the phase angle and the horizontal axis representing the drive frequency. c represents the transfer ratio, with the vertical axis representing the transfer ratio and the horizontal axis representing the drive frequency. The transfer ratio, multiplied by the ratio of the number of turns of the primary coil to the number of turns of the secondary coil, roughly gives the step-up ratio.
可知在耦合系数(k)为0.5的情况下，通过将Q值设为8以上，而满足流入至一次线圈的电流相位较驱动一次线圈的驱动电路的驱动电压的相位略微延迟的条件。在图16的例中，在耦合系数(k)为0.5的情况下，传递比为最高的频率为85kHz。在所述频率下，流入至一次线圈的电流的延迟角Δθ为25度以下，cosθ、即功率因素为0.9以上，因此可说85kHz为最佳的驱动频率。It can be seen that when the coupling coefficient (k) is 0.5, by setting the Q value to 8 or greater, the condition that the phase of the current flowing into the primary coil is slightly delayed relative to the phase of the drive voltage of the drive circuit driving the primary coil is met. In the example of Figure 16, when the coupling coefficient (k) is 0.5, the frequency at which the transfer ratio reaches its highest is 85 kHz. At this frequency, the delay angle Δθ of the current flowing into the primary coil is less than 25 degrees, and cosθ, or the power factor, is greater than 0.9, making 85 kHz the optimal drive frequency.
在所述最佳的驱动频率下，流过二次侧的谐振电容器的谐振电流相位为0度。即，可无相位延迟地将所述谐振电流相位信息通过相位信息传递单元而传递至驱动电路，若对驱动电路进行驱动则自动地以最佳的驱动频率来驱动开关单元。另外，所述开关条件也为ZVS动作，因此即便将开关单元设为半桥接构成也可实现稳定的ZVS动作。At the optimal drive frequency, the resonant current flowing through the secondary-side resonant capacitor has a phase of 0 degrees. This means that the resonant current phase information is transmitted to the drive circuit via the phase information transmission unit without phase delay. When the drive circuit is activated, the switching unit is automatically driven at the optimal drive frequency. Furthermore, the switching conditions also provide for ZVS operation, enabling stable ZVS operation even when the switching unit is configured as a half-bridge.
如此，在本发明中，在基于谐振电流的相位信息而决定的驱动频率下，驱动电路被驱动而自动地成为ZVS动作。但在无线电力传送中需要高Q值，因此略有相位延迟(或时间延迟)便无法成为ZVS动作，故而需要相位修正。Thus, in the present invention, the drive circuit is driven at a drive frequency determined based on the phase information of the resonant current, automatically achieving ZVS operation. However, wireless power transmission requires a high Q factor, so even a slight phase delay (or time delay) prevents ZVS operation, necessitating phase correction.
其次，对目标Q值的设定进行说明。Next, the setting of the target Q value will be described.
谐振电路的Q值是由二次线圈的漏电感(L)、谐振电容器的电容(C)、及二次线圈侧的等效负载电阻(R)以如下方式决定。The Q value of the resonant circuit is determined by the leakage inductance (L) of the secondary coil, the capacitance (C) of the resonant capacitor, and the equivalent load resistance (R) on the secondary coil side as follows.
[数2][Number 2]
(串联谐振电路)(Series Resonance Circuit)
(并联谐振电路)(Parallel Resonance Circuit)
在本发明中，二次线圈与谐振电容器的连接可利用串联连接、并联连接中的任一种，但以下对并联连接的示例进行说明。原因在于：作为本发明之一的在二次线圈并联地设置谐振电容器的谐振，为在自驱动侧观察的情况下成为串联谐振，在自负载侧观察的情况下成为并联谐振的变形的谐振电路。其被称为串并联负载谐振(Serial Parallel-LoadedResonance)等其他各种名称。所述情况下的Q的计算式应用并联谐振。即，为了将Q值设定为规定的高值，而与等效负载电阻R相比使谐振电容器的电容C变大，使二次线圈的漏电感L变小。In the present invention, the connection between the secondary coil and the resonant capacitor can be either a series connection or a parallel connection, but the following example of a parallel connection is described. The reason is that the resonance of the resonant capacitor in parallel with the secondary coil, which is one of the present inventions, is a deformed resonant circuit that becomes a series resonance when viewed from the drive side and a parallel resonance when viewed from the load side. It is called a serial parallel load resonance (Serial Parallel-Loaded Resonance) and other various names. The calculation formula of Q in this case applies parallel resonance. That is, in order to set the Q value to a specified high value, the capacitance C of the resonant capacitor is increased compared to the equivalent load resistance R, and the leakage inductance L of the secondary coil is reduced.
另外，本发明中的漏电感Lsc的定义由以下式确定。In addition, the leakage inductance Lsc in the present invention is defined by the following formula.
[数3][Number 3]
LsC＝L2·(1-k2)LsC = L2 ·(1-k2 )
此处，L2为二次线圈的电感或独立的第三线圈的电感。Here,L2 is the inductance of the secondary coil or the inductance of the independent tertiary coil.
关于漏电感，还有时根据各国的工业会或学会，将由Regarding leakage inductance, sometimes according to the industrial associations or societies of various countries,
[数4][Number 4]
Le＝L2·(1-k)Le =L2 ·(1-k)
规定的Le设为漏电感，存在各种情况，无法统一。The prescribedLe is set as leakage inductance, but there are various cases and it is impossible to unify them.
另外，在本发明中，将二次线圈与谐振电容器耦合而在二次侧构成的谐振电路，包含谐振电容器相对于二次线圈并联、或串联连接而构成中的任一种。另外，对于自第三线圈提取要连接到负载的电力的构成将在下文进行叙述。In the present invention, the resonant circuit formed on the secondary side by coupling the secondary coil and the resonant capacitor includes configurations in which the resonant capacitor is connected in parallel or in series with the secondary coil. Furthermore, the configuration for extracting power from the third coil to be connected to the load will be described below.
在本发明中，将k设为耦合系数，将目标二次侧的谐振电路的Q值设定为满足Q＝2/k2的值以上的值。In the present invention, k is set as a coupling coefficient, and the Q value of the target secondary-side resonance circuit is set to a value that satisfies Q=2/k2 or more.
图17是通过仿真求出用以自一次线圈观察获得功率因素时所必须的最小所需Q值的图。横轴为驱动频率。纵轴中，a表示一次线圈相对于一次线圈的开关电压的电流相位，b表示二次侧的谐振电容器的谐振电流相位，c6表示传递比(传递系数)。Figure 17 shows the minimum required Q value required to achieve the power factor observed from the primary coil, calculated through simulation. The horizontal axis represents the drive frequency. On the vertical axis, a represents the current phase of the primary coil relative to the primary coil switching voltage, b represents the resonant current phase of the secondary-side resonant capacitor, and c6 represents the transfer ratio (transfer coefficient).
图18是对用以自一次线圈观察获得功率因素1时最小所需Q值伴随耦合系数k的降低而逐渐接近k2·Q＝2的关系的情况进行说明的图。FIG. 18 is a diagram illustrating a situation in which the minimum required Q value for obtaining a power factor of 1 as viewed from the primary coil gradually approaches the relationship of k2 ·Q=2 as the coupling coefficient k decreases.
根据图18明显可知，k2·Q的值当k变小时逐渐接近2，且不会超过2。其在无线电力传送中，在一次线圈与二次线圈的距离远且耦合系数k足够小的情况下，用以自一次线圈观察获得功率因素1的二次侧的谐振电路的Q值符合：As is apparent from FIG18 , the value of k2 ·Q gradually approaches 2 as k decreases, and never exceeds 2. In wireless power transmission, when the primary and secondary coils are far apart and the coupling coefficient k is sufficiently small, the Q value of the secondary-side resonant circuit for achieving a power factor of 1 as viewed from the primary coil satisfies:
[数5][Number 5]
k2·Q＝2 [数式1]k2 ·Q＝2 [Formula 1]
此处，在考虑到自一次线圈检测流入至二次侧的谐振电路的谐振电流的相位信息的动作的情况下，一次线圈的电流相位曲线必然需要横穿0度的横轴，在所述情况下，伴随驱动频率增加，相位需要以自正、即电容性，成为负、即感应性的方式横穿。Here, considering the operation of detecting the phase information of the resonant current flowing from the primary coil to the resonant circuit on the secondary side, the current phase curve of the primary coil must cross the horizontal axis of 0 degrees. In this case, as the driving frequency increases, the phase must cross from positive, that is, capacitive, to negative, that is, inductive.
因此，在将最低限的Q值设为高于[数式1]的Q值的情况下，一次线圈的电流相位曲线必然横穿0度的横轴。对所述情况进行说明的为图19。Therefore, when the minimum Q value is set to a value higher than the Q value of [Formula 1], the current phase curve of the primary coil inevitably crosses the horizontal axis of 0 degrees. FIG19 illustrates this situation.
在图19中，a、b、c分别与图17相对应。在图19中，在耦合系数k＝0.7的情况下，一次线圈的电流相位曲线如a所示，伴随驱动频率增加而以自正、即电容性，成为负、即感应性的方式横穿0度的横轴。In Figure 19, a, b, and c correspond to Figure 17. In Figure 19, when the coupling coefficient k = 0.7, the primary coil current phase curve, as shown in a, crosses the horizontal axis of 0 degrees, transitioning from positive (i.e., capacitive) to negative (i.e., inductive) as the drive frequency increases.
另外，所述说明为k＝0.7的情况，但k即便为其他值也相同。此处，在将功率因素正好设为1的情况下，一次线圈的电流相位略微提前便会发生硬开关，因此通常的动作点是将感应性、即一次线圈的电流相位略微延迟的点设为动作点。已知所述为ZVS动作条件。The above description uses k = 0.7, but the same applies to other values of k. Here, if the power factor is exactly 1, hard switching occurs if the primary coil current phase is slightly advanced. Therefore, the normal operating point is set at a point where the inductive current, or the primary coil current phase, is slightly delayed. This is known as the ZVS operating condition.
所述情况下，若相位的延迟角为0度～-30度的范围，则可说功率因素足够好，效率非常良好。另外，在使用来自流入至谐振电容器的谐振电流的相位信息的情况下，若所述相位信息无相位延迟或时间延迟，则只要依照所述相位信息来驱动一次侧的开关单元，则在耦合系数小的情况下也以高Q值的状态自动地在ZVS的动作点进行动作。In this case, if the phase delay angle is within the range of 0 to -30 degrees, the power factor is sufficiently good and the efficiency is very good. Furthermore, when using phase information from the resonant current flowing into the resonant capacitor, if this phase information has no phase or time delay, driving the primary-side switching element according to this phase information allows automatic operation at the ZVS operating point with a high Q value, even with a low coupling coefficient.
其次，对本发明中的电力控制进行说明。Next, the power control in the present invention will be described.
通常，电力控制是以使开关单元的占空比小于50％的方式可变地进行。Normally, power control is performed variably so that the duty ratio of the switching unit is less than 50%.
图20是对本发明的电力控制的一例进行说明的图。a表示谐振电流的相位信息，b表示一次线圈的电流波形，c、d表示将开关单元(Q2、Q1)设为场效应晶体管(Field EffectTransistor，FET)或绝缘栅双极性晶体管(Insulated Gate Bipolar Transistor，IGBT)等的情况下的栅极控制电压。Figure 20 illustrates an example of power control according to the present invention. (a) shows the phase information of the resonant current, (b) the current waveform of the primary coil, and (c) and (d) the gate control voltages when the switching elements (Q2, Q1) are field effect transistors (FETs) or insulated gate bipolar transistors (IGBTs).
本发明中的电力控制是通过如下来进行，即，基于谐振电流的相位信息，将驱动一次线圈的驱动电路的开关单元设为ON，在固定时间后设为OFF。在所述情况下，通常担心硬开关，但在本发明中，一次线圈的电流相位已较开关相位迟(参照b)，因此进行工作周期控制的情况下的电流相位较ON相位进一步延迟(参照c、d)，故而不会发生硬开关。此时，为了不使(Q2、Q1)同时成为ON而通常需要若干空载时间(Dead time)，在所述说明中省略。The power control in this invention is performed by turning on the switch in the drive circuit that drives the primary coil based on the phase information of the resonant current, and then turning it off after a fixed time. In this case, there is a general concern about hard switching. However, in this invention, the current phase in the primary coil is already delayed compared to the switching phase (see b). Therefore, when performing duty cycle control, the current phase is further delayed compared to the ON phase (see c and d), thus preventing hard switching. In this case, a certain amount of dead time is usually required to prevent (Q2 and Q1) from turning on simultaneously, but this is omitted in this description.
图21是对本发明的电力控制的另一例进行说明的图。在所述电力控制中，将控制工作周期的一侧设为仅开关单元的一个或同时成为ON的一对，另一个或另一对通过反转信号而控制。此时，在由反转信号控制的一侧仍需要若干的空载时间(Dead time)(参照d)。Figure 21 illustrates another example of power control according to the present invention. In this power control, one side of the control duty cycle is controlled by turning on only one switching element or a pair of switching elements simultaneously, while the other switching element or pair is controlled by an inverted signal. In this case, a certain amount of dead time is still required on the side controlled by the inverted signal (see d).
此种控制方法被称为不均等半桥接或不均等全桥接控制。所述控制方法在二次线圈容易产生偶数次高次谐波电压，但在本发明中将Q值设定为非常高，因此二次线圈的电压几乎接近正弦波故而不存在问题。This control method is called unequal half-bridge or unequal full-bridge control. This control method tends to generate even-order harmonic voltages in the secondary winding, but in the present invention, the Q value is set very high, so the voltage in the secondary winding is almost sinusoidal, so there is no problem.
图22是对进行本发明的电力控制的情况下的与一次线圈的电流相位的关系进行说明的图。FIG. 22 is a diagram illustrating the relationship between the current phase of the primary coil and the current phase when the power control according to the present invention is performed.
以本发明的控制方法进行控制的情况下的驱动频率也上升，根据图22也可明确得知，若频率上升则驱动电压的ON相位会较谐振电流的相位信息的相位进一步延迟。另外，虽功率因素降低，但同时传递比也变低，因此可控制的电力的范围非常大。When controlled using the control method of the present invention, the driving frequency also increases. As shown in Figure 22, as the frequency increases, the on-phase of the driving voltage further lags behind the phase information of the resonant current. Furthermore, while the power factor decreases, the transfer ratio also decreases, significantly widening the controllable power range.
在以上说明的无线电力传送装置中，将谐振电容器耦合于二次线圈而构成谐振电路，但在使用电磁感应方式的例如Qi(气)规格中，如本发明中的二次侧的谐振电路并非为必需。因此，对如下情况进行说明，即，为了保持与Qi规格的相容性，并且应用本发明，而如图5C那样与二次线圈并排地设置第三线圈，自所述第三线圈提取要连接到负载的电力。In the wireless power transmission device described above, a resonant capacitor is coupled to the secondary coil to form a resonant circuit. However, in electromagnetic induction systems, such as the Qi standard, a secondary-side resonant circuit, as described in the present invention, is not essential. Therefore, to maintain compatibility with the Qi standard and apply the present invention, a third coil is provided alongside the secondary coil, as shown in Figure 5C , and power is extracted from this third coil for connection to a load.
图23是表示可保持与Qi规格的相容性且进行效率改善的电路的一例的图。第三线圈190可如图5C所示，接近二次线圈140且作为独立的线圈而设置，也可如图23或图5B所示，设为如下第三线圈190：在二次线圈140中包含作为自耦变压器的第三线圈，且以相对于二次线圈140中感应的电压为降压的关系而卷绕。FIG23 illustrates an example of a circuit that maintains compliance with the Qi standard while improving efficiency. Third coil 190 can be provided as an independent coil close to secondary coil 140, as shown in FIG5C . Alternatively, third coil 190 can be provided as follows: the third coil serving as an autotransformer within secondary coil 140, wound to reduce the voltage induced in secondary coil 140, as shown in FIG23 or FIG5B .
将谐振电容器(Cp)150耦合于二次线圈140，在Qi相容规格时，通过开关181设为OFF，在进行效率改善的情况下设为ON而Cp作为谐振电容器150进行动作。与此同时地，二次线圈140侧的开关183成为OFF，开关185成为ON。在开关183与开关185，在与二次侧GND之间连接未图示的负载。当开关181成为ON时，谐振电路的Q值变高。Resonant capacitor (Cp) 150 is coupled to secondary coil 140. Switch 181 is turned off when Qi-compliant, and turned on to improve efficiency, allowing Cp to operate as resonant capacitor 150. Simultaneously, switch 183 on the secondary coil 140 side is turned off, and switch 185 is turned on. A load (not shown) is connected between switches 183 and 185 and the secondary-side GND. When switch 181 is turned on, the Q value of the resonant circuit increases.
若以此种方式进行动作，则在一次线圈110产生功率因素良好的频率，因此将由设置于一次侧的谐振电流相位检测单元160c检测到的谐振电流波形与其反转积分波形加以合成而进行相位修正，基于所述谐振电流相位信息来驱动高频电源的驱动电路即可。另外，在图23的电路图中，就开关181、开关183、开关185而言，通过二极管而使用FET或晶体管，但只要为可进行开关动作的元件则并不限定于此，可使用任何元件。Operating in this manner generates a frequency with a good power factor in primary coil 110. Therefore, the resonant current waveform detected by resonant current phase detection section 160c on the primary side is synthesized with its inverted integrated waveform to perform phase correction. This resonant current phase information is then used to drive the high-frequency power supply driver circuit. In the circuit diagram of FIG23 , FETs or transistors are used instead of diodes for switches 181, 183, and 185. However, this is not a limitation and any element capable of switching operation may be used.
如图5C或图5B、图23所示，若将第三线圈以相对于二次线圈中感应的电压为降压的关系而卷绕，则连接于第三线圈的负载电阻与降压比的平方成反比地被阻抗转换，而在二次线圈虚拟地连接有高值的等效负载电阻，因此可依照所述比而将谐振电路的Q值设定得高。而且，通过所述降压比的设定，还可容易地设定为所需的Q＝2/k2所规定的值以上的Q值。As shown in Figures 5C, 5B, and 23, if the third coil is wound so as to step down the voltage induced in the secondary coil, the load resistance connected to the third coil undergoes impedance conversion inversely proportional to the square of the step-down ratio. This creates a virtual high-value equivalent load resistance connected to the secondary coil, allowing the resonant circuit's Q factor to be set high in accordance with this ratio. Furthermore, by setting the step-down ratio, it is possible to easily set the Q factor to a value greater than or equal to the desired value defined by Q = 2/k² .
进而，由于谐振电流与圈数成反比，故谐振电流所引起的铜耗与电流的平方成比例地变少，从而可减少发热，提升效率。Furthermore, since the resonant current is inversely proportional to the number of turns, the copper loss caused by the resonant current decreases in proportion to the square of the current, thereby reducing heat generation and improving efficiency.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2014/002552WO2015173847A1 (en) | 2014-05-14 | 2014-05-14 | Contactless power transfer device |
| JPPCT/JP2014/002552 | 2014-05-14 | ||
| PCT/JP2014/004827WO2015173850A1 (en) | 2014-05-14 | 2014-09-19 | Wireless power transfer device |
| Publication Number | Publication Date |
|---|---|
| HK1231637A1 HK1231637A1 (en) | 2017-12-22 |
| HK1231637Btrue HK1231637B (en) | 2020-05-15 |
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