CN103368377A - Preceding-stage EMI filtering protective circuit of driving power source - Google Patents

Abstract

Translated fromChinese

本发明公开了一种驱动电源前级EMI滤波保护电路，包括熔断器、温敏电阻、浪涌保护电路、差模干扰抑制电路、共模干扰抑制电路等。本发明采用多级滤波结构对由电网进入的电磁干扰信号进行有效的滤除，采用不同泄放电压值的三个压敏电阻对浪涌电压进行泄放保护，靠近接入口的熔断器和温敏电阻不但对过电流发生时进行断开保护而且对整个驱动电源起到一个软启动的作用。本发明具有电路简单、体积小、成本低廉、可靠性好、插入损耗高等优点。

The invention discloses a front-stage EMI filter protection circuit of a driving power supply, which includes a fuse, a temperature-sensitive resistor, a surge protection circuit, a differential-mode interference suppression circuit, a common-mode interference suppression circuit, and the like. The present invention adopts a multi-stage filter structure to effectively filter out the electromagnetic interference signal entering from the power grid, and uses three varistors with different discharge voltage values to discharge and protect the surge voltage. The sensitive resistor not only disconnects the protection when overcurrent occurs, but also acts as a soft start for the entire driving power supply. The invention has the advantages of simple circuit, small size, low cost, good reliability, high insertion loss and the like.

Description

Translated fromChinese

一种驱动电源前级EMI滤波保护电路A pre-stage EMI filter protection circuit for driving power supply

技术领域technical field

本发明涉及EMI滤波和抗浪涌电路。The present invention relates to EMI filtering and anti-surge circuits.

背景技术Background technique

驱动电源多采用的是开关电源类型，体积小，效率高，但是开关电源高频率的开关动作带来严重的电磁干扰问题，同时为了驱动电源稳定可靠的工作需要防止来自外界的电磁干扰。EMI滤波保护电路不但可以有效的阻止来自外界的电磁干扰影响驱动电源内部电路，而且可以阻止驱动电源自身的电磁干扰进入电网造成污染。The driving power supply mostly adopts the switching power supply type, which is small in size and high in efficiency. However, the high-frequency switching action of the switching power supply brings serious electromagnetic interference problems. At the same time, it is necessary to prevent electromagnetic interference from the outside for the stable and reliable operation of the driving power supply. The EMI filter protection circuit can not only effectively prevent the electromagnetic interference from the outside from affecting the internal circuit of the drive power supply, but also prevent the electromagnetic interference of the drive power supply itself from entering the power grid and causing pollution.

现有的驱动电源EMI滤波保护电路大多采用过于简单的一级或两级滤波结构，插入损耗值不够大，对电磁干扰的滤波效果不够好，从而导致由于电磁干扰问题引起的驱动电源失效甚至引起其他系统失效的事故频发，电磁干扰分为传导型和辐射型，而最主要的干扰是传导型，一个具有良好插入损耗特性的EMI滤波器可以解决绝大部分问题。另外，一般的驱动电源的前级浪涌保护只考虑分别在火线和零线上接上一个压敏电阻连接至大地，而本发明不但考虑到相线与大地之间的浪涌电压防护，而且考虑到相线与相线之间的浪涌电压的防护，使得安全性进一步提高。 Most of the existing drive power supply EMI filter protection circuits adopt too simple one-stage or two-stage filter structure, the insertion loss value is not large enough, and the filtering effect on electromagnetic interference is not good enough, which leads to the failure of the drive power supply caused by electromagnetic interference and even causes Accidents of other system failures occur frequently. Electromagnetic interference is divided into conduction type and radiation type, and the most important type of interference is conduction type. An EMI filter with good insertion loss characteristics can solve most of the problems. In addition, the pre-stage surge protection of the general driving power supply only considers connecting a varistor to the ground respectively on the live line and the neutral line, while the present invention not only considers the surge voltage protection between the phase line and the ground, but also Considering the protection of the surge voltage between the phase lines, the safety is further improved. the

发明内容Contents of the invention

本发明针对现有技术的不足，提供一种稳定可靠、高插入损耗的滤波保护电路。The invention aims at the deficiencies of the prior art and provides a filter protection circuit which is stable, reliable and has high insertion loss.

一种驱动电源前级EMI滤波保护电路，包括用于驱动电源软启动和过流保护的温敏电阻，其特征在于：第一压敏电阻的一端通过熔断器接入到交流电网输入的火线端，第一压敏电阻的另一端通过温敏电阻接入到交流电网输入的零线端，第一压敏电阻与熔断器的公共端通过第二压敏电阻连接至大地，第一压敏电阻与温敏电阻的公共端通过第三压敏电阻连接至大地，第一差模电容与第一压敏电阻并联，第一共模电容与第二压敏电阻并联，第二共模电容与第三压敏电阻并联，由第一共模电感和第二共模电感组成的共模扼流圈的输入端并联于第一差模电容的两端，第二差模电容并联于共模扼流圈的输出端，第二差模电容的一端通过第三共模电容连接至大地，第二差模电容的另一端通过第四共模电容连接至大地，第三差模电容的一端通过第一差模电感连接至第三共模电容的非接地端，第三差模电容的另一端通过第二差模电感连接至第四共模电容的非接地端；第五共模电容和第六共模电容都是穿心电容，其接地端都连接至大地，第五共模电容的其中一个穿心端连接至第一差模电感和第三差模电容的公共端，另一穿心端为本电路的第一输出端，第六共模电容的其中一个穿心端连接至第二差模电感和第三差模电容的公共端，另一穿心端为本电路的第二输出端。 An EMI filter protection circuit at the front stage of a drive power supply, including a temperature sensitive resistor for soft start and overcurrent protection of the drive power supply, characterized in that: one end of the first piezoresistor is connected to the live wire terminal of the AC grid input through a fuse , the other end of the first varistor is connected to the neutral terminal of the AC grid input through the temperature sensitive resistor, the common end of the first varistor and the fuse is connected to the ground through the second varistor, and the first varistor The common end of the temperature sensitive resistor is connected to the ground through the third piezoresistor, the first differential mode capacitor is connected in parallel with the first piezoresistor, the first common mode capacitor is connected in parallel with the second piezoresistor, and the second common mode capacitor is connected with the second piezoresistor in parallel Three varistors are connected in parallel, the input end of the common mode choke composed of the first common mode inductor and the second common mode inductor is connected in parallel with both ends of the first differential mode capacitor, and the second differential mode capacitor is connected in parallel with the common mode choke One end of the second differential mode capacitor is connected to the ground through the third common mode capacitor, the other end of the second differential mode capacitor is connected to the ground through the fourth common mode capacitor, and one end of the third differential mode capacitor is connected to the ground through the first The differential-mode inductor is connected to the non-ground terminal of the third common-mode capacitor, and the other end of the third differential-mode capacitor is connected to the non-ground terminal of the fourth common-mode capacitor through the second differential-mode inductor; the fifth common-mode capacitor and the sixth common-mode capacitor The mode capacitors are all feedthrough capacitors, and their ground terminals are connected to the ground. One of the feedthrough terminals of the fifth common mode capacitor is connected to the common terminal of the first differential mode inductor and the third differential mode capacitor, and the other feedthrough terminal is At the first output end of the circuit, one of the feed-through ends of the sixth common-mode capacitor is connected to the common end of the second differential-mode inductor and the third differential-mode capacitor, and the other feed-through end is the second output end of the circuit. the

本发明电路结构简单，能够在较低的成本下实现较高的插入损耗和可靠的保护功能。紧靠交流电网电压输入端放置一个熔断器F1和一个负温度系数的温敏电阻RT1，当后续电路短路或者其他原因引起的电路电流忽然增大，熔断器F1立即熔断以断开电路与电网的连接进行保护，而RT1的作用一方面是电路的软启动作用，电路接通瞬间RT1温度较低阻值较大，启动电流就开始较小，随后温度升高电流增大到正常工作值，这就实现了软启动，软启动过程可以大大减小元器件的电流应力，起到保护元器件的作用，RT1另一方面的作用是当某种原因导致温度过高时响应电阻值立即变低，从而使回路电流迅速增大而使熔断器断开，也起到一定的保护作用；压敏电阻R1提供了两相线之间的过电压保护，压敏电阻R2和R3分别提供了火线与零线与大地之间的过电压保护；电容Cx1、Cx2、Cx3都是用于滤除差模干扰信号的电容，对共模干扰信号不起作用，电容Cy1、Cy2用于滤除共模干扰信号，但是同时两者相当于串联的接于两相线之间，即等效为Cy1//Cy2大小的差模电容，同样，电容Cy3和Cy4，Cy5和Cy6都分别作为共模电容组的同时也等效为Cy3//Cy4和Cy5//Cy6大小的差模电容，在本发明当中所有差模电容（x电容）根据插入损耗的实际效果采用相等的电容值，所有的共模电容（y电容）根据插入损耗的实际效果和国际安规限制的漏电流大小综合选取同等大小的容量值；两个共模电感Lc1、Lc2绕制方向相反匝数相同共同组成共模扼流圈，共模干扰信号在两个绕组中流过的方向相反，产生的磁通量相互抵消从而抑制了共模干扰，Ld1和Ld2是差模电感，差模干扰信号经过两个差模电感而被限制，两个差模电感对共模干扰信号也有一定的抑制作用。本发明具有体积小、成本低廉、稳定可靠、插入损耗高等优点。The circuit structure of the invention is simple, and can realize higher insertion loss and reliable protection function at lower cost. Place a fuse F1 and a temperature-sensitive resistor RT1 with a negative temperature coefficient close to the input terminal of the AC grid voltage. When the subsequent circuit short circuit or other reasons cause a sudden increase in the circuit current, the fuse F1 will blow immediately to disconnect the circuit from the grid. The connection is used for protection, and the function of RT1 is the soft start function of the circuit on the one hand. When the circuit is turned on, the temperature of RT1 is lower and the resistance value is larger, the starting current starts to be small, and then the temperature rises and the current increases to the normal working value. The soft start is realized. The soft start process can greatly reduce the current stress of the components and protect the components. On the other hand, the function of RT1 is that when the temperature is too high for some reason, the response resistance value immediately becomes low. As a result, the loop current increases rapidly and the fuse is disconnected, which also plays a certain protective role; the varistor R1 provides overvoltage protection between the two-phase lines, and the varistors R2 and R3 respectively provide the live wire and neutral wire. Overvoltage protection between the line and the ground; capacitors Cx1, Cx2, and Cx3 are used to filter out differential-mode interference signals, and have no effect on common-mode interference signals. Capacitors Cy1 and Cy2 are used to filter out common-mode interference signals , but at the same time, the two are equivalent to being connected in series between the two phase lines, which is equivalent to a differential mode capacitor of the size Cy1//Cy2. Similarly, capacitors Cy3 and Cy4, Cy5 and Cy6 are respectively used as common mode capacitors. Simultaneously It is also equivalent to the differential mode capacitance of Cy3//Cy4 and Cy5//Cy6. In the present invention, all differential mode capacitances (x capacitance) adopt equal capacitance values according to the actual effect of insertion loss, and all common mode capacitances (y Capacitance) According to the actual effect of insertion loss and the leakage current limited by international safety regulations, the capacity value of the same size is comprehensively selected; the two common-mode inductors Lc1 and Lc2 have the same number of turns in opposite winding directions to form a common-mode choke coil. Interference signals flow in the opposite direction in the two windings, and the generated magnetic flux cancels each other to suppress common-mode interference. Ld1 and Ld2 are differential-mode inductances, and differential-mode interference signals are limited by passing through two differential-mode inductances. Inductance also has a certain inhibitory effect on common-mode interference signals. The invention has the advantages of small size, low cost, stability and reliability, high insertion loss and the like.

附图说明Description of drawings

图1是本发明的电路原理图。Fig. 1 is the schematic circuit diagram of the present invention.

图2是实施例1的共模插入损耗图。FIG. 2 is a common mode insertion loss diagram ofEmbodiment 1. FIG.

图3是实施例1的差模插入损耗图。FIG. 3 is a differential mode insertion loss diagram ofEmbodiment 1. FIG.

具体实施方式Detailed ways

实施例1Example 1

如图1所示，一种驱动电源前级EMI滤波保护电路，包括用于驱动电源软启动和过流保护的温敏电阻RT1，第一压敏电阻R1的一端通过熔断器F1接入到交流电网输入的火线端，第一压敏电阻R1的另一端通过温敏电阻RT1接入到交流电网输入的零线端，第一压敏电阻R1与熔断器F1的公共端通过第二压敏电阻R2连接至大地，第一压敏电阻R1与温敏电阻RT1的公共端通过第三压敏电阻R3连接至大地，第一差模电容Cx1与第一压敏电阻R1并联，第一共模电容Cy1与第二压敏电阻R2并联，第二共模电容Cy2与第三压敏电阻R3并联，Lc1和Lc2组成的共模扼流圈的输入端并联于第一差模电容Cx1的两端，第二差模电容Cx2并联于共模扼流圈的输出端，第二差模电容Cx2的一端通过第三共模电容Cy3连接至大地，第二差模电容Cx2的另一端通过第四共模电容Cy4连接至大地，第三差模电容Cx3的一端通过第一差模电感Ld1连接至第三共模电容Cy3的非接地端，第三差模电容Cx3的另一端通过第二差模电感Ld2连接至第四共模电容Cy4的非接地端；第五共模电容Cy5（穿心电容）和第六共模电容Cy6（穿心电容）的接地端都连接至大地，第五共模电容Cy5的其中一个穿心端连接至第一差模电感Ld1和第三差模电容Cx3的公共端，另一穿心端作为本滤波保护电路输出端的一端，第六共模电容Cy6的其中一个穿心端连接至第二差模电感Ld2和第三差模电容Cx3的公共端，另一穿心端作为本滤波保护电路输出端的另一端，Cx1、 Cx2 、Cx3、Cy1、Cy2、Cy3、Cy4等电容均为无极性电容。本发明针对我国目前220V的电网电压值，压敏电阻R1的泄放电压值为350V，压敏电阻R2 、R3的泄放电压值均为700V，差模电容Cx1、Cx2、Cx3的电容值均选择0.22uF，共模电容Cy1、Cy2、Cy3、Cy4、Cy5、Cy6的电容值均选择1.2nF，共模电感Lc1、Lc2的电感值均选择为8mH，差模电感Ld1、Ld2的电感值均选择为110uH。依上述元件参数，共模插入损耗、差模插入损耗如图2和图3所示，可以看出对于10KHZ~30MHZ典型的电磁干扰频率范围的电磁干扰信号都有很高的插入损耗和很好的抑制效果。As shown in Figure 1, an EMI filter protection circuit at the front stage of the driving power supply includes a temperature-sensitive resistor RT1 for soft-starting and over-current protection of the driving power supply. One end of the first piezoresistor R1 is connected to the AC through the fuse F1. The live wire end of the grid input, the other end of the first varistor R1 is connected to the neutral end of the AC grid input through the temperature sensitive resistor RT1, and the common end of the first varistor R1 and the fuse F1 is connected through the second varistor R2 is connected to the ground, the common terminal of the first piezoresistor R1 and the temperature-sensitive resistor RT1 is connected to the ground through the third piezoresistor R3, the first differential mode capacitor Cx1 is connected in parallel with the first piezoresistor R1, and the first common mode capacitor Cy1 is connected in parallel with the second varistor R2, the second common-mode capacitor Cy2 is connected in parallel with the third varistor R3, the input end of the common-mode choke formed by Lc1 and Lc2 is connected in parallel with both ends of the first differential-mode capacitor Cx1, The second differential mode capacitor Cx2 is connected in parallel to the output terminal of the common mode choke coil, one end of the second differential mode capacitor Cx2 is connected to the ground through the third common mode capacitor Cy3, and the other end of the second differential mode capacitor Cx2 is connected to the ground through the fourth common mode The capacitor Cy4 is connected to the ground, one end of the third differential mode capacitor Cx3 is connected to the non-ground end of the third common mode capacitor Cy3 through the first differential mode inductor Ld1, and the other end of the third differential mode capacitor Cx3 is passed through the second differential mode inductor Ld2 Connect to the non-ground terminal of the fourth common-mode capacitor Cy4; the ground terminals of the fifth common-mode capacitor Cy5 (feedthrough capacitor) and the sixth common-mode capacitor Cy6 (feedthrough capacitor) are connected to the ground, and the fifth common-mode capacitor Cy5 One of the through-holes of the first differential mode inductor Ld1 and the common end of the third differential mode capacitor Cx3, the other one of the through-holes as the output end of the filter protection circuit, one of the sixth common-mode capacitor Cy6 through the The terminal is connected to the common terminal of the second differential mode inductor Ld2 and the third differential mode capacitor Cx3. All are non-polarized capacitors. The present invention is aimed at the current grid voltage value of 220V in my country. The discharge voltage value of varistor R1 is 350V, the discharge voltage value of varistor R2 and R3 is 700V, and the capacitance values of differential mode capacitors Cx1, Cx2, and Cx3 are all equal. Choose 0.22uF, choose 1.2nF for the common-mode capacitors Cy1, Cy2, Cy3, Cy4, Cy5, and Cy6, choose 8mH for the common-mode inductors Lc1 and Lc2, and choose 8mH for the differential-mode inductors Ld1 and Ld2. The choice is 110uH. According to the above component parameters, common mode insertion loss and differential mode insertion loss are shown in Figure 2 and Figure 3. It can be seen that the EMI signals in the typical EMI frequency range of 10KHZ~30MHZ have very high insertion loss and good inhibitory effect.

Claims (1)

1. driving power prime EMI filter protective circuit, comprise the thermo-sensitive resistor for driving power soft start and overcurrent protection, it is characterized in that: an end of the first piezo-resistance is linked into the live wire end of AC network input by fuse, the other end of the first piezo-resistance is linked into the zero line side of AC network input by thermo-sensitive resistor, the common port of the first piezo-resistance and fuse is connected to the earth by the second piezo-resistance, the common port of the first piezo-resistance and thermo-sensitive resistor is connected to the earth by the 3rd piezo-resistance, the first differential mode capacitor is in parallel with the first piezo-resistance, the first common mode capacitance is in parallel with the second piezo-resistance, the second common mode capacitance is in parallel with the 3rd piezo-resistance, two inputs of the common mode choke that is comprised of the first common mode inductance and the second common mode inductance are connected to respectively the two ends of the first differential mode capacitor, and two outputs of common mode choke are connected to respectively the two ends of the second differential mode capacitor; One end of the second differential mode capacitor is connected to the earth by the 3rd common mode capacitance, and the other end is connected to the earth by the 4th common mode capacitance; One end of the 3rd differential mode capacitor is connected to the ungrounded end of the 3rd common mode capacitance by the first differential mode inductance, and the other end is connected to the ungrounded end of the 4th common mode capacitance by the second differential mode inductance; The 5th common mode capacitance and the 6th common mode capacitance all are feedthrough capacitors, its earth terminal all is connected to the earth, one of them punching end of the 5th common mode capacitance is connected to the common port of the first differential mode inductance and the 3rd differential mode capacitor, another punching end is first output of this circuit, one of them punching end of the 6th common mode capacitance is connected to the common port of the second differential mode inductance and the 3rd differential mode capacitor, and another punching end is second output of this circuit.

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