技术领域Technical Field
本发明属于功率变换器控制领域，特别涉及基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略。The invention belongs to the field of power converter control, and in particular relates to a predictive control strategy of a ZVS four-switch Buck-Boost converter based on node current.
背景技术Background Art
在输出电压在输入电压范围内的应用中，通常采用具有升压和降压能力的DC-DC变换器。具有这种能力的基本变换器包括Buck-Boost、Cuk、Zeta和SEPIC四种，其中Buck-Boost变换器和Cuk变换器的输入输出电压极性相反，开关管电压应力较高；而Zeta和SEPIC变换器输出正电压，但所需无源器件较多，不利于变换器功率密度的提高，同样存在开关管电压应力较高的问题。将双管Buck-Boost变换器的二极管全部换为可控开关管，得到一个四开关Buck-Boost变换器，该变换器输出电压为正，电压应力小，无源元件少，在分布式电源、电动汽车、光伏电源等领域得到了广泛的应用。四开关Buck-Boost变换器工作于四边形电感电流工作模式可以实现四个开关管的软开关，提高变换器的效率。根据是否存在续流阶段T4，将四边形电感电流调制的四开关Buck-Boost变换器工作模式分为伪断续电流模式(Pseudo Discontinuous Current Mode,PDCM)和伪临界电流模式(Pseudo CriticalContinuous Current Mode,PCRM)。目前对于四边形电感电流调制的四开关Buck-Boost变换器控制策略，单个周期内的控制时序都是按照T1、T2、T3、T4对应的模态进行控制的，基于该控制时序，在PCRM模式时，-IZVS比较与开关周期结束这两个判断条件只能用一个，未能得到充分利用，为此，本发明提出一种采用新的控制时序，且具有较高动态性能与稳定性的节点电流预测控制策略。本发明通过调整开关周期内的控制时序简化了四开关Buck-Boost电路单周期内各模态占空比的计算过程，提出一种基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略，具有较强稳定性，能够实现对负载变化的快速跟随，提高变换器的动态性能。In applications where the output voltage is within the input voltage range, a DC-DC converter with boost and buck capabilities is usually used. The basic converters with this capability include Buck-Boost, Cuk, Zeta and SEPIC. The input and output voltage polarities of Buck-Boost and Cuk converters are opposite, and the voltage stress of the switch tube is high; while Zeta and SEPIC converters output positive voltages, but require more passive devices, which is not conducive to improving the power density of the converter, and also have the problem of high voltage stress of the switch tube. By replacing all the diodes of the two-tube Buck-Boost converter with controllable switch tubes, a four-switch Buck-Boost converter is obtained. The output voltage of this converter is positive, the voltage stress is small, and the passive components are few. It has been widely used in distributed power supplies, electric vehicles, photovoltaic power supplies and other fields. The four-switch Buck-Boost converter working in the quadrilateral inductor current working mode can realize the soft switching of the four switch tubes and improve the efficiency of the converter. According to whether there is a freewheeling stage T4 , the operation mode of the four-switch Buck-Boost converter with quadrilateral inductor current modulation is divided into a pseudo discontinuous current mode (Pseudo Discontinuous Current Mode, PDCM) and a pseudo critical current mode (Pseudo Critical Continuous Current Mode, PCRM). At present, for the control strategy of the four-switch Buck-Boost converter with quadrilateral inductor current modulation, the control timing in a single cycle is controlled according to the mode corresponding to T1 , T2 , T3 , and T4 . Based on the control timing, in the PCRM mode, only one of the two judgment conditions, -IZVS comparison and the end of the switching cycle, can be used, which cannot be fully utilized. Therefore, the present invention proposes a node current prediction control strategy that adopts a new control timing and has higher dynamic performance and stability. The present invention simplifies the calculation process of each mode duty cycle in a single cycle of a four-switch Buck-Boost circuit by adjusting the control timing in the switching cycle, and proposes a ZVS four-switch Buck-Boost converter predictive control strategy based on node current, which has strong stability, can achieve fast follow-up of load changes, and improve the dynamic performance of the converter.
发明内容Summary of the invention
基于现有技术中存在的问题，本发明的目的在于提供简便、稳定且具有较高动态性能的基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略，其主要思想是在单控制开关周期内提出新的控制时序，对电感电流进行采样并预测，判断变换器的工作状态，计算出单开关周期内各个阶段的占空比和时间，控制开关管的开通或关断，使变换器快速达到稳态。Based on the problems existing in the prior art, the purpose of the present invention is to provide a simple, stable and highly dynamic performance node current-based ZVS four-switch Buck-Boost converter predictive control strategy. The main idea is to propose a new control timing within a single control switching cycle, sample and predict the inductor current, judge the working state of the converter, calculate the duty cycle and time of each stage within a single switching cycle, control the on or off of the switch tube, and make the converter quickly reach a steady state.
为实现上述目的，本发明提供如下技术方案：To achieve the above object, the present invention provides the following technical solutions:
基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略，所述四开关Buck-Boost电路由一个电感和四个开关管组成，四个开关管分别为Q1、Q2、Q3、Q4，其中Q1、Q2组成左边桥臂，Q3、Q4组成右边桥臂，两个桥臂共地，电感两端分别连接两个桥臂的中点，同一桥臂的两个开关管互补导通，即Q1、Q2互补导通，Q3、Q4互补导通，桥臂上两个开关管需要设置死区时间td。A predictive control strategy for a ZVS four-switch Buck-Boost converter based on node current is provided. The four-switch Buck-Boost circuit is composed of an inductor and four switch tubes. The four switch tubes are Q1 , Q2 , Q3 , and Q4 , respectively. Q1 and Q2 form a left bridge arm, and Q3 and Q4 form a right bridge arm. The two bridge arms are grounded. Two ends of the inductor are respectively connected to the midpoints of the two bridge arms. The two switch tubes in the same bridge arm are complementary turned on, that is, Q1 and Q2 are complementary turned on, and Q3 and Q4 are complementary turned on. The two switch tubes on the bridge arm need to be set with a dead time td .
优选的，所述的四开关Buck-Boost电路工作如下：T1时间段内，Q1、Q4导通，Q2、Q3截止；T2时间段内Q1、Q3导通，Q2、Q4截止；T3时间段内，Q2、Q3导通，Q1、Q4截止；T4时间段内，Q2、Q4导通，Q1、Q3截止。当四开关Buck-Boost变换器工作在PDCM模式时，单个控制开关周期内的工作阶段有T3、T4、T1、T2；当四开关Buck-Boost变换器工作在PCRM模式时，单个开关周期内的工作阶段有T3、T1、T2。T1阶段过渡到T2阶段电感电流的节点为P点，T2阶段过渡到T3阶段电感电流的节点为Q点。Preferably, the four-switch Buck-Boost circuit operates as follows: in theT1 period,Q1 andQ4 are turned on, andQ2 andQ3 are turned off; in theT2 period,Q1 andQ3 are turned on, andQ2 andQ4 are turned off; in theT3 period,Q2 andQ3 are turned on, andQ1 andQ4 are turned off; in theT4 period,Q2 andQ4 are turned on, andQ1 andQ3 are turned off. When the four-switch Buck-Boost converter operates in the PDCM mode, the working stages in a single control switch cycle areT3 ,T4 ,T1 , andT2 ; when the four-switch Buck-Boost converter operates in the PCRM mode, the working stages in a single switch cycle areT3 ,T1 , andT2 . The node where the inductor current transitions from theT1 stage to theT2 stage is point P, and the node where the inductor current transitions from theT2 stage to theT3 stage is point Q.
优选的，所述的四开关Buck-Boost电路，在单个控制周期内的控制时序为T3、T4、T1、T2，在采样电感电流开关周期初始值即Q点的电流值、输入电压及输出电压后送入控制器，计算电路单个开关周期内各个阶段的时间，进而控制开关管的开关动作使得电路进入稳态。Preferably, the control timing of the four-switch Buck-Boost circuit in a single control cycle is T3 , T4 , T1 , and T2 . After sampling the initial value of the inductor current switching cycle, i.e., the current value at point Q, the input voltage, and the output voltage, the controller calculates the time of each stage in a single switching cycle of the circuit, and then controls the switching action of the switch tube to make the circuit enter a steady state.
所述控制方法实施的具体步骤如下：The specific steps of implementing the control method are as follows:
步骤一：根据额定输入电压Vin与额定输出电压Vo，计算最小软开关电流IZVS，具体计算公式为：Step 1: Calculate the minimum soft switching current IZVS according to the rated input voltage Vin and the rated output voltage Vo . The specific calculation formula is:
IZVS＝2Coss·max{Vin,Vo}/tdIZVS ＝2Coss ·max{Vin ,Vo }/td
式中，Coss为开关管的寄生电容，td为死区时间；In the formula, Coss is the parasitic capacitance of the switch tube, and td is the dead time;
步骤二：采样输入电压vin与输出电压vo，判断电路升降压工作状态，判断方式为：Step 2: Sample the input voltage vin and the output voltage vo to determine the circuit buck-boost working state. The determination method is:
当vin＜vo时，四开关Buck-Boost变换器工作在升压状态；When vin ＜vo , the four-switch Buck-Boost converter works in the boost state;
当vin≥vo时，四开关Buck-Boost变换器工作在降压状态；When vin ≥ vo , the four-switch Buck-Boost converter operates in the step-down state;
步骤三：用采样得到的输入电压vin与输出电压vo，计算出临界节点电流值IP_b和IP_Io_max，其中IP_b为变换器工作于PDCM与PCRM模式交界时P点电感电流对应值，IP_Io_max为最大功率点处P点电感电流对应值，具体计算公式为：Step 3: Use the sampled input voltage vin and output voltage vo to calculate the critical node current valuesIP_b andIP_Io_max , whereIP_b is the corresponding value of the inductor current at point P when the converter works at the junction of PDCM and PCRM modes, andIP_Io_max is the corresponding value of the inductor current at point P at the maximum power point. The specific calculation formula is:
式中，Ts为开关周期，L为电感值；Where,Ts is the switching period, L is the inductance value;
步骤四：将采样得到的输出电压vo与给定输出电压基准值Vo_ref进行比较，将误差信号输入PI补偿器，得到P节点电感电流参考信号IPI，并通过限幅环节将IPI限制在0与IP_Io_max之间；Step 4: Compare the sampled output voltage vo with the given output voltage reference value Vo_ref , input the error signal into the PI compensator, obtain the P-node inductor current reference signal IPI , and limit IPI between 0 and IP_Io_max through the limiting link;
步骤五：将P节点电感电流参考信号IPI与临界电流值IP_b进行比较，判断变换器工作模式，判断方式为：Step 5: Compare the P-node inductor current reference signal IPI with the critical current value IP_b to determine the converter operation mode. The determination method is:
当IPI＜IP_b时，变换器工作于PDCM模式；When IPI ＜IP_b , the converter operates in PDCM mode;
当IPI≥IP_b时，变换器工作于PCRM模式；When IPI ≥IP_b , the converter works in PCRM mode;
步骤六：采样输入电压vin、输出电压vo和开关周期内电感电流初始值即Q点的电流值iL_Q，根据电路的工作模式，计算单个开关周期内T3、T4、T1、T2时间段对应的占空比d3、d4、d1、d2；各种工作模态下具体计算公式为：Step 6: Sample the input voltagevin , the output voltagev0 and the initial value of the inductor current in the switching cycle, i.e., the current valueiL_Q at the Q point. According to the working mode of the circuit, calculate the duty ratiosd3 ,d4 ,d1 ,d2 corresponding to the time periodsT3 ,T4 ,T1 ,T2 in a single switching cycle; the specific calculation formulas under various working modes are:
当电路工作在PDCM升压模式时：When the circuit works in PDCM boost mode:
当电路工作在PDCM降压模式时：When the circuit works in PDCM buck mode:
当电路工作在PCRM模式时：When the circuit works in PCRM mode:
步骤七：通过占空比d3、d4、d1、d2计算单个开关周期内各个阶段的实际时间T3、T4、T1、T2，具体公式为：Step 7: Calculate the actual time T3 , T4 , T1 , T2 of each stage in a single switching cycle through the duty cycles d3 , d 4 , d1 ,d2. The specific formula is:
T2＝Ts-T1-T3-T4T2 =Ts -T1 -T3 -T4
步骤八：根据单个开关周期内4个阶段的实际时间T3、T4、T1、T2控制开关管Q3、Q4、Q1、Q2的开关动作；Step 8: Control the switching actions of the switch tubes Q3 , Q4 , Q1 , Q2 according to the actual times T3 , T4 , T1 , T2 of the four stages in a single switching cycle;
步骤九：重复上述步骤二至步骤八，实现开关周期的循环。Step 9: Repeat the above steps 2 to 8 to complete the switching cycle.
优选的，采用所述策略，变换器工作在升压模式时均可以稳定，变换器工作于降压模式时的稳定条件为Vo<Vin＜2Vo。Preferably, by adopting the strategy, the converter can be stable when operating in the boost mode, and the stability condition when the converter operates in the buck mode is Vo <Vin <2Vo .
优选的，所述策略可以对步骤三中最大功率点电感电流P点对应的值IP_Io_max的表达式进行线性拟合，线性拟合公式为：Preferably, the strategy can perform a linear fitting on the expression of the valueIP_Io_max corresponding to the maximum power point inductor current P in step 3, and the linear fitting formula is:
IP_Io_max＝avin+bvo+cIP_Io_max = avin + bvo + c
式中，a、b、c为常数，可根据变换器的参数来确定。Where a, b, and c are constants and can be determined based on the parameters of the converter.
与现有技术相比，本发明的有益效果是：Compared with the prior art, the present invention has the following beneficial effects:
1.本发明针对ZVS四开关Buck-Boost变换器在一个控制开关周期内提出了新的控制时序，以Q1的关断时刻作为一个控制开关周期的开始，即开关模态顺序由T1、T2、T3、T4变为T3、T4、T1、T2，能够有效简化各模态占空比的计算过程，降低控制系统的复杂度；1. The present invention proposes a new control timing for a ZVS four-switch Buck-Boost converter within a control switching cycle, taking the turn-off moment ofQ1 as the beginning of a control switching cycle, that is, the switching mode sequence is changed fromT1 ,T2 ,T3 ,T4 toT3 ,T4 ,T1 ,T2 , which can effectively simplify the calculation process of each mode duty cycle and reduce the complexity of the control system;
2.本发明提出的预测控制策略更能够保证软开关的实现，从而提高变换器的效率；2. The predictive control strategy proposed in the present invention can better ensure the realization of soft switching, thereby improving the efficiency of the converter;
3.本发明提出的预测控制策略提高了系统的动态性能，在负载或输入电压发生突变等情况下，可以快速达到稳态，且不会产生次谐波振荡问题，有效遏制电路中电流与电压过冲的问题；3. The predictive control strategy proposed in the present invention improves the dynamic performance of the system. When the load or input voltage changes suddenly, the system can quickly reach a steady state without generating subharmonic oscillation problems, effectively curbing the current and voltage overshoot problems in the circuit.
4.本发明提出的预测控制策略能够适应不同的开关频率、电感等电路参数，适应性好。4. The predictive control strategy proposed in the present invention can adapt to different switching frequencies, inductance and other circuit parameters and has good adaptability.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
为了更清楚地说明本发明具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
图1为四开关Buck-Boost变换器的拓扑及控制示意图。FIG1 is a topology and control diagram of a four-switch Buck-Boost converter.
图2为四开关Buck-Boost变换器基于节点电流预测控制策略工作在升压PDCM模式和PCRM模式的示意图。FIG. 2 is a schematic diagram of a four-switch Buck-Boost converter operating in boost PDCM mode and PCRM mode based on a node current prediction control strategy.
图3为四开关Buck-Boost变换器基于节点电流预测控制策略工作在降压PDCM模式和PCRM模式的示意图。FIG3 is a schematic diagram of a four-switch Buck-Boost converter operating in a step-down PDCM mode and a PCRM mode based on a node current prediction control strategy.
图4为四开关Buck-Boost变换器基于节点电流预测控制策略在升压模式下负载跳变时的输出电流、电感电流和输出电压波形。FIG4 shows the output current, inductor current and output voltage waveforms of the four-switch Buck-Boost converter when the load changes in the boost mode based on the node current prediction control strategy.
图5为四开关Buck-Boost变换器基于节点电流预测控制策略在等压模式下负载跳变时的输出电流、电感电流和输出电压波形。FIG5 shows the output current, inductor current and output voltage waveforms of the four-switch Buck-Boost converter when the load jumps in the equal-voltage mode based on the node current prediction control strategy.
图6为四开关Buck-Boost变换器基于节点电流预测控制策略在降压模式下负载跳变时的输出电流、电感电流和输出电压波形。FIG6 shows the output current, inductor current and output voltage waveforms of the four-switch Buck-Boost converter when the load changes in the buck mode based on the node current prediction control strategy.
图7为四开关Buck-Boost变换器基于节点电流预测控制策略在满载时输入电压变化时输出电流、电感电流和输出电压波形。FIG7 shows the output current, inductor current and output voltage waveforms of a four-switch Buck-Boost converter when the input voltage changes at full load based on the node current prediction control strategy.
具体实施方式DETAILED DESCRIPTION
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
请参阅图1至图7，本发明提供了基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略的实施例子：Please refer to FIG. 1 to FIG. 7 , the present invention provides an implementation example of a predictive control strategy for a ZVS four-switch Buck-Boost converter based on node current:
如图1为四开关Buck-Boost电路的电路拓扑及控制示意图，基于节点电流的ZVS四开关Buck-Boost变换器预测控制策略，所述四开关Buck-Boost电路由一个电感和四个开关管组成，四个开关管分别为Q1、Q2、Q3、Q4，其中Q1、Q2组成左边桥臂，Q3、Q4组成右边桥臂，两个桥臂共地，电感两端分别连接两个桥臂的中点，同一桥臂的两个开关管互补导通，即Q1、Q2互补导通，Q3、Q4互补导通，桥臂上两个开关管需要设置死区时间td，变换器还包括输入电容Cin和输出电容Co，用以滤除纹波。T1时间段内，Q1、Q4导通，Q2、Q3截止；T2时间段内Q1、Q3导通，Q2、Q4截止；T3时间段内，Q2、Q3导通，Q1、Q4截止；T4时间段内，Q2、Q4导通，Q1、Q3截止。As shown in FIG1 , a circuit topology and control schematic diagram of a four-switch Buck-Boost circuit is shown, and a predictive control strategy of a ZVS four-switch Buck-Boost converter based on node current is used. The four-switch Buck-Boost circuit is composed of an inductor and four switch tubes, and the four switch tubes are Q1 , Q2 , Q3 , and Q4 , respectively. Q1 and Q2 form a left bridge arm, and Q3 and Q4 form a right bridge arm. The two bridge arms are grounded, and the two ends of the inductor are connected to the midpoints of the two bridge arms, respectively. The two switch tubes of the same bridge arm are complementary turned on, that is, Q1 and Q2 are complementary turned on, and Q3 and Q4 are complementary turned on. The two switch tubes on the bridge arm need to be set with a dead time td . The converter also includes an input capacitor Cin and an output capacitorCo to filter out ripples. During theT1 time period,Q1 andQ4 are turned on, andQ2 andQ3 are turned off; during theT2 time period,Q1 andQ3 are turned on, andQ2 andQ4 are turned off; during theT3 time period,Q2 andQ3 are turned on, andQ1 andQ4 are turned off; during theT4 time period,Q2 andQ4 are turned on, andQ1 andQ3 are turned off.
当四开关Buck-Boost变换器工作在伪断续电流模式时，单个控制开关周期内的工作阶段有T3、T4、T1、T2；当四开关Buck-Boost变换器工作在伪临界电流模式时，单个开关周期内的工作阶段有T3、T1、T2。T1阶段过渡到T2阶段电感电流的节点为P点，T2阶段过渡到T3阶段电感电流的节点为Q点。When the four-switch Buck-Boost converter operates in the pseudo discontinuous current mode, the working stages in a single control switch cycle are T3 , T4 , T1 , and T2 ; when the four-switch Buck-Boost converter operates in the pseudo critical current mode, the working stages in a single switch cycle are T3 , T1 , and T2 . The node where the inductor current transitions from the T1 stage to the T2 stage is point P, and the node where the inductor current transitions from the T2 stage to the T3 stage is point Q.
所述四开关Buck-Boost变换器在单个控制周期内的控制时序为T3、T4、T1、T2，在采样电感电流开关周期初始值即Q点的电流值、输入电压及输出电压后送入控制器，计算电路单个开关周期内各个阶段的时间，进而控制开关管的开关动作使得电路进入稳态。The control timing of the four-switch Buck-Boost converter in a single control cycle is T3 , T4 , T1 , and T2 . After sampling the initial value of the inductor current switching cycle, i.e., the current value at point Q, the input voltage, and the output voltage, the controller calculates the time of each stage in a single switching cycle of the circuit, and then controls the switching action of the switch tube to make the circuit enter a steady state.
所述控制方法具体步骤如下：The specific steps of the control method are as follows:
步骤一：根据额定输入电压Vin与额定输出电压Vo，计算最小软开关电流IZVS，具体计算公式为：Step 1: Calculate the minimum soft switching current IZVS according to the rated input voltage Vin and the rated output voltage Vo . The specific calculation formula is:
IZVS＝2Coss·max{Vin,Vo}/tdIZVS ＝2Coss ·max{Vin ,Vo }/td
式中，Coss为开关管的寄生电容，td为死区时间；In the formula, Coss is the parasitic capacitance of the switch tube, and td is the dead time;
步骤二：采样输入电压vin与输出电压vo，判断电路升降压工作状态，判断方式为：Step 2: Sample the input voltage vin and the output voltage vo to determine the circuit buck-boost working state. The determination method is:
当vin＜vo时，四开关Buck-Boost变换器工作在升压状态；When vin ＜vo , the four-switch Buck-Boost converter works in the boost state;
当vin≥vo时，四开关Buck-Boost变换器工作在降压状态；When vin ≥ vo , the four-switch Buck-Boost converter operates in the step-down state;
步骤三：用采样得到的输入电压vin与输出电压vo，计算出临界节点电流值IP_b和IP_Io_max，其中IP_b为变换器工作于PDCM与PCRM模式交界时P点电感电流对应值，IP_Io_max为最大功率点处P点电感电流对应值，具体计算公式为：Step 3: Use the sampled input voltage vin and output voltage vo to calculate the critical node current valuesIP_b andIP_Io_max , whereIP_b is the corresponding value of the inductor current at point P when the converter works at the junction of PDCM and PCRM modes, andIP_Io_max is the corresponding value of the inductor current at point P at the maximum power point. The specific calculation formula is:
式中，Ts为开关周期，L为电感值；Where,Ts is the switching period, L is the inductance value;
步骤四：将采样得到的输出电压vo与给定输出电压基准值Vo_ref进行比较，将误差信号输入PI补偿器，得到P节点电感电流参考信号IPI，并通过限幅环节将IPI限制在0与IP_Io_max之间；Step 4: Compare the sampled output voltage vo with the given output voltage reference value Vo_ref , input the error signal into the PI compensator, obtain the P-node inductor current reference signal IPI , and limit IPI between 0 and IP_Io_max through the limiting link;
步骤五：将P节点电感电流参考信号IPI与临界电流值IP_b进行比较，判断变换器工作模式，判断方式为：Step 5: Compare the P-node inductor current reference signal IPI with the critical current value IP_b to determine the converter operation mode. The determination method is:
当IPI＜IP_b时，变换器工作于PDCM模式；When IPI ＜IP_b , the converter operates in PDCM mode;
当IPI≥IP_b时，变换器工作于PCRM模式；When IPI ≥IP_b , the converter works in PCRM mode;
步骤六：采样输入电压vin、输出电压vo和开关周期内电感电流初始值即Q点的电流值iL_Q，根据电路的工作模式，计算单个开关周期内T3、T4、T1、T2时间段对应的占空比d3、d4、d1、d2；各种工作模态下具体计算公式为：Step 6: Sample the input voltagevin , the output voltagev0 and the initial value of the inductor current in the switching cycle, i.e., the current valueiL_Q at the Q point. According to the working mode of the circuit, calculate the duty ratiosd3 ,d4 ,d1 ,d2 corresponding to the time periodsT3 ,T4 ,T1 ,T2 in a single switching cycle; the specific calculation formulas under various working modes are:
当电路工作在PDCM升压模式时：When the circuit works in PDCM boost mode:
当电路工作在PDCM降压模式时：When the circuit works in PDCM buck mode:
当电路工作在PCRM模式时：When the circuit works in PCRM mode:
步骤七：通过占空比d3、d4、d1、d2计算单个开关周期内各个阶段的实际时间T3、T4、T1、T2，具体公式为：Step 7: Calculate the actual time T3 , T4 , T1 , T2 of each stage in a single switching cycle through the duty cycles d3 , d 4 , d1 ,d2. The specific formula is:
T2＝Ts-T1-T3-T4T2 =Ts -T1 -T3 -T4
步骤八：根据单个开关周期内4个阶段的实际时间T3、T4、T1、T2控制开关管Q1～Q4的开关动作；Step 8: Control the switching actions of the switch tubes Q1 to Q4 according to the actual times T3 , T4 , T1 , and T2 of the four stages in a single switching cycle;
步骤九：重复上述步骤二至步骤八，实现开关周期的循环。Step 9: Repeat the above steps 2 to 8 to complete the switching cycle.
通过上述控制方法，可实现如图2、图3所示的不同工作模式下的工作波形。Through the above control method, the working waveforms in different working modes as shown in FIG. 2 and FIG. 3 can be realized.
为了进一步说明本控制策略的优越性，下面给出本发明的一个仿真实例。In order to further illustrate the superiority of this control strategy, a simulation example of the present invention is given below.
根据表1给出的四开关Buck-Boost电路参数，用Simulink仿真软件搭建了仿真电路。图4、图5和图6分别给出了变换器工作在升压模式、等压模式和降压模式时负载在30W和300W之间发生跳变时的动态波形，输入电压分别为100V、200V和300V，左图为负载由30W切换至300W过程中的波形放大图，右图为负载由300W切换至30W过程中的波形放大图；从图4、图5和图6可以看出负载发生较大突变时，变换器在全输入电压范围内都可以很快的到达稳态，且不会产生次谐波振荡问题，有效遏制电路中电流与电压过冲的问题，具有较好的动态性能；图7给出了变换器满载时输入电压在100V和300V之间发生变化的波形图，左图为输入电压由100V变为300V的波形图，右图为输入电压由300V变为100V的波形图，可以看出在输入电压发生较大变化时，变换器可以快速达到稳态。According to the four-switch Buck-Boost circuit parameters given in Table 1, a simulation circuit was built using Simulink simulation software. FIG4, FIG5 and FIG6 respectively show the dynamic waveforms when the load jumps between 30W and 300W when the converter works in boost mode, equal voltage mode and buck mode, and the input voltage is 100V, 200V and 300V respectively. The left figure is an enlarged waveform of the load switching from 30W to 300W, and the right figure is an enlarged waveform of the load switching from 300W to 30W. It can be seen from FIG4, FIG5 and FIG6 that when the load undergoes a large sudden change, the converter can quickly reach a steady state within the full input voltage range, and will not produce subharmonic oscillation problems, effectively curbing the current and voltage overshoot problems in the circuit, and having good dynamic performance. FIG7 shows the waveform of the input voltage changing between 100V and 300V when the converter is fully loaded. The left figure is a waveform of the input voltage changing from 100V to 300V, and the right figure is a waveform of the input voltage changing from 300V to 100V. It can be seen that when the input voltage changes greatly, the converter can quickly reach a steady state.
表1四开关Buck-Boost电路仿真参数Table 1 Four-switch Buck-Boost circuit simulation parameters
以上所述实施例仅表达了本申请的一种具体的实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。The above-described embodiment only expresses a specific implementation method of the present application, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of this application shall be based on the attached claims.
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| CN202410601373.8ACN118920863A (en) | 2024-05-15 | 2024-05-15 | Node current-based ZVS four-switch Buck-Boost converter prediction control strategy |
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