CN207612203U - Capacitors in series voltage equalizing circuit - Google Patents

Abstract

The utility model provides a kind of capacitor series average-voltage circuit, and the half-bridge inversion circuit includes the filter capacitor bridge arm being connected in parallel, equalizing resistance bridge arm, diode bridge arm and IGBT bridge arms；The high frequency transformer circuit includes primary side winding and vice-side winding, and high frequency transformer is additionally provided with three auxiliary windings, the pressure for being responsible for each filter capacitor in filter capacitor bridge arm；Filter capacitor in the half-bridge inversion circuit occur terminal voltage it is unequal when, the auxiliary winding of the high frequency transformer generates induced voltage by being coupled with the primary side winding, is that the unequal filter capacitor of terminal voltage carries out charge and discharge so that the terminal voltage on each filter capacitor is equal.The utility model does not need complicated control circuit, can reach automatically equalizing voltage by the effect of auxiliary winding at work, have the characteristics that compact-sized, voltage equalizing is good, can be used in the practical applications such as semi-bridge inversion type plasma cutting machine.

Description

Capacitors in series voltage equalizing circuit

technical field

The utility model relates to a voltage equalizing circuit in the technical field of power electronic conversion, in particular to a capacitor series voltage equalizing circuit.

Background technique

In the current small and medium power applications, the half-bridge circuit has the advantages of simple structure, convenient control, and the ideal withstand voltage effect can be achieved by using capacitors in series on the DC side, so it has been widely used. pressure problem. The common causes of capacitor uneven voltage include capacitor size, leakage resistance, capacitor initial voltage, and line parameter symmetry.

The harm of capacitor uneven voltage cannot be ignored. If the voltage of the capacitors is not balanced, some capacitors will be broken down due to high voltage, and the rest of the capacitors will also fail due to this. In severe cases, personal safety may be endangered. Therefore, it is very necessary to take appropriate pressure equalization measures.

After research on existing voltage equalization technologies, most voltage equalization technologies use feedback control methods. Although these methods can achieve capacitor voltage equalization to a certain extent, they require complex control circuits and greatly increase costs.

Utility model content

Aiming at the defects in the prior art, the purpose of this utility model is to provide a capacitor series voltage equalizing circuit. When the filter capacitor in the half-bridge inverter circuit has an uneven terminal voltage due to capacitance or leakage current, etc., the primary side The auxiliary winding generates an induced voltage by coupling with the secondary winding, so that it can charge and discharge the filter capacitors with unequal terminal voltages so that the terminal voltages on each filter capacitor are in phase. It has a compact structure, no need for a control circuit, and a good voltage equalization effect. The advantages.

The utility model is achieved through the following technical solutions.

The utility model provides a capacitor series voltage equalizing circuit, which includes a half-bridge inverter circuit and a high-frequency transformer circuit;

The half-bridge inverter circuit includes a filter capacitor bridge arm, a voltage equalizing resistor bridge arm, a diode bridge arm and an IGBT bridge arm connected in parallel between the positive pole and the negative terminal of the DC power supply to complete DC-AC power conversion;

The high-frequency transformer circuit includes a primary winding and a secondary winding, and the high-frequency transformer is also provided with three auxiliary windings, and the two ends of the three auxiliary windings are connected to the filter capacitor bridge arm and the voltage equalizing resistor bridge arm , which is responsible for the voltage equalization of each filter capacitor in the filter capacitor bridge arm;

When the filter capacitors in the half-bridge inverter circuit have unequal terminal voltages, the auxiliary winding of the high-frequency transformer generates an induced voltage by coupling with the primary winding to charge and discharge the filter capacitors with unequal terminal voltages. Make the terminal voltages on each filter capacitor equal.

Preferably, the half-bridge inverter circuit includes: first to fourth filter capacitors, first to fourth equalizing resistors, first to sixth diodes, and first to second IGBTs;

The high-frequency transformer circuit includes a primary winding, a secondary winding, and first to third auxiliary windings arranged on the secondary side;

in:

The positive pole of the DC power supply is connected to the positive pole of the first filter capacitor, one end of the first voltage equalizing resistor, the cathode of the first diode, the cathode of the fifth diode, and the drain of the first IGBT;

The negative pole of the DC power supply is connected to the negative pole of the fourth filter capacitor, one end of the fourth equalizing resistor, the anode of the fourth diode, the anode of the sixth diode and the source of the second IGBT;

The negative pole of the first filter capacitor is connected to the positive pole of the second filter capacitor, the other end of the first voltage equalizing resistor, one end of the second voltage equalizing resistor and the end of the same name of the first auxiliary winding;

The negative pole of the second filter capacitor and the positive pole of the third filter capacitor, the other end of the second equalizing resistor, one end of the third equalizing resistor, the anode of the second diode, the cathode of the third diode, the end of the same name of the second auxiliary winding, and the primary side The windings are not connected to the end of the same name;

The negative pole of the third filter capacitor is connected to the positive pole of the fourth filter capacitor, the other end of the third equalizing resistor, the other end of the fourth equalizing resistor and the end of the same name of the third auxiliary winding; the anode of the first diode is connected to the cathode of the second diode and The first auxiliary winding is not connected to the terminal with the same name;

The anode of the third diode is connected to the cathode of the fourth diode and the non-identical end of the third auxiliary winding; the anode of the fifth diode is connected to the cathode of the sixth diode and the non-identical end of the second auxiliary winding;

The source of the first IGBT is connected to the drain of the second IGBT and the same terminal of the primary winding.

Compared with the prior art, the utility model has the following beneficial effects:

The high-frequency transformer described in the utility model is provided with three auxiliary windings. When the filter capacitor in the half-bridge inverter circuit has an uneven terminal voltage due to capacitance or leakage current, the three auxiliary windings pass through the primary side winding. The coupling of the coupling generates an induced voltage, and the induced voltage is applied to the filter capacitor through the diode, so as to realize the self-balancing of the filter capacitor without using an additional control circuit, which is beneficial to reduce the complexity of the circuit, save costs, and has a good voltage equalization effect.

In the utility model, the primary side winding and the auxiliary winding are coupled to generate induced voltage, so that the filter capacitors with unequal terminal voltages can be charged and discharged to make the terminal voltages on each filter capacitor equal. It has the advantages of compact structure, no control circuit and good voltage equalization effect.

Description of drawings

Fig. 1 is a circuit diagram of capacitors connected in series for voltage equalization in an embodiment of the present invention.

Detailed ways

The utility model is described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the utility model, but do not limit the utility model in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present utility model. These all belong to the protection domain of the present utility model.

The utility model provides a capacitor series voltage equalizing circuit, comprising four filter capacitors C1-C4, four equalizing resistors R1-R4, six diodes D1-D6, two IGBTs S1-S2, three auxiliary windings SD1- SD3 and the primary winding P1 and secondary winding N1 of the high frequency transformer Tr1.

specific:

Four filter capacitors C1-C4 are connected in series to form filter capacitor bridge arms;

Four voltage equalizing resistors R1-R4 are connected in series to form a voltage equalizing resistor bridge arm;

in:

The positive pole of the first filter capacitor C1 is connected to the positive pole of the DC power supply and one end of the first voltage equalizing resistor R1, and its cathode is connected to the positive pole of the second filter capacitor C2, the other end of the first voltage equalizing resistor R1, and the terminal of the second voltage equalizing resistor R2. One end is connected to one end of the first auxiliary winding SD1;

The cathode of the second filter capacitor C2 is connected to the positive pole of the third filter capacitor C3, the other end of the second equalizing resistor R2, one end of the third equalizing resistor R3, and one end of the primary winding P1;

The cathode of the third filter capacitor C3 is connected to the positive pole of the filter capacitor C4, the other end of the third equalizing resistor R3, one end of the equalizing resistor R4, and one end of the third auxiliary winding D3;

The cathode of the filter capacitor C4 is connected to the negative pole of the DC power supply.

specific:

Six diodes D1-D6 form a diode bridge arm, diodes D1-D4 are connected in series in sequence, and the diodes D5-D6 are connected in series in sequence, wherein:

The cathode of the first diode D1 is connected to the anode of the DC power supply, and its anode is connected to the cathode of the second diode D2 and the other end of the first auxiliary winding SD1,

The anode of the second diode D2 is connected to the cathode of the third diode D3 and one end of the second auxiliary winding SD2;

The anode of the third diode D3 is connected to the cathode of the fourth diode D4 and the other end of the third auxiliary winding SD3;

The anode of the fourth diode D4 is connected to the negative pole of the DC power supply;

The cathode of the fifth diode D5 is connected to the anode of the DC power supply, and its anode is connected to the cathode of the sixth diode D6 and the other end of the second auxiliary winding SD2;

The anode of the sixth diode D6 is connected to the negative pole of the DC power supply.

Specifically, two IGBTs S1-S2 are connected in sequence to form an IGBT bridge arm, wherein:

The collector of the first IGBT S1 is connected to the positive pole of the DC power supply, the emitter of the first IGBT S1 is connected to the collector of the second IGBT S2 and the other end of the primary winding, and the emitter of the second IGBT S2 is connected to the negative pole of the DC power supply. The first IGBT S1 includes an antiparallel diode FWD1, and the second IGBT S2 includes an antiparallel diode FWD2.

The four bridge arms of the filter capacitor bridge arm, the voltage equalizing resistor bridge arm, the diode bridge arm and the IGBT bridge arm are connected between the positive pole and the negative terminal of the DC power supply.

Shown in Fig. 1 with reference to, be an embodiment circuit diagram of the present utility model, wherein:

The positive pole of the DC power supply is connected to the positive pole of the first filter capacitor C1, one end of the first equalizing resistor R1, the cathode of the first diode D1, the cathode of the fifth diode D5, and the drain of the first IGBT S1;

The negative pole of the DC power supply is connected to the negative pole of the fourth filter capacitor C4, one end of the fourth equalizing resistor R4, the anode of the fourth diode D4, the anode of the sixth diode D6, and the source of the second IGBT S2;

The negative pole of the first filter capacitor C1 is connected to the positive pole of the second filter capacitor C2, the other end of the first equalizing resistor R1, one end of the second equalizing resistor R2, and the same-named end of the first auxiliary winding SD1;

The negative pole of the second filter capacitor C2 and the positive pole of the third filter capacitor C3, the other end of the second equalizing resistor R2, one end of the third equalizing resistor R3, the anode of the second diode D2, the cathode of the third diode D3, the second auxiliary The same-named end of the winding SD2 is connected to the non-identical end of the primary winding P1;

The negative pole of the third filter capacitor C3 is connected to the positive pole of the fourth filter capacitor C4, the other end of the third voltage equalizing resistor R3, the other end of the fourth voltage equalizing resistor R4, and the same-named end of the third auxiliary winding SD3;

The anode of the first diode D1 is connected to the cathode of the second diode D2 and the non-identical end of the first auxiliary winding SD1; the anode of the third diode D3 is connected to the cathode of the fourth diode D4 and the non-identical end of the third auxiliary winding SD3 connected;

The anode of the fifth diode D5 is connected to the cathode of the sixth diode D6 and the non-identical terminal of the second auxiliary winding SD2;

The source of the first IGBT S1 is connected to the drain of the second IGBT S2 and the same terminal of the primary winding P1.

The gates of S1-S2 can be connected to the corresponding drivers according to the needs; the two ends of the secondary winding N1 can be connected to any rectifier circuit, such as half-wave rectifier or full-bridge rectifier, etc., which can be set according to actual needs.

In the utility model, the capacitance values of the filter capacitors C1-C4 are equal, the resistance values of the equalizing resistors R1-R4 are equal, the number of turns of the primary and secondary windings of the high-frequency transformer is equal, and the number of turns of the second auxiliary winding SD2 is the same as that of the primary winding P1 The number of turns is equal, the number of turns of the first auxiliary winding SD1 and the number of turns of the third auxiliary winding SD3 are equal, which are half of the number of turns of the primary winding P1.

The setting of auxiliary winding SD1 is responsible for the equalization of C1 and C2, the setting of auxiliary winding SD3 is responsible for the equalization of C3 and C4, and the setting of auxiliary winding SD2 is responsible for the equalization of C1 and C2 after series connection, and C3 and C4 after series connection.

Take the situation where the voltages of the first filter capacitor C1 and the second filter capacitor C2 are not equal as an example:

When the first IGBT S1 is turned on and the second IGBT S2 is turned off, the first filter capacitor C1 and the second filter capacitor C2 charge the primary winding P1 of the transformer together, and the energy is transferred from the primary winding P1 to the secondary winding N1. At this time, the voltage on the primary winding P1 and the voltage on the secondary winding N1 are equal to U ₀ , the voltage U ₁ on the first filter capacitor C1 should be equal to the voltage U ₂ on the second filter capacitor C2, and is

When the voltage U1 on the first filter capacitor C1 is greater than the voltage _U2 on the second filter capacitor C2 due to the difference in capacitance or leakage resistance between the first filter capacitor C1 and the second filter capacitor _C2 , the first auxiliary winding SD1 The induced voltage is generated by coupling with the secondary winding N1, and the induced voltage generated on the first auxiliary winding SD1 is also known from the relationship between the number of turns of the two windings. At this time, the first auxiliary winding SD1 forms a loop with the second diode D2 and the second filter capacitor C2, the first auxiliary winding SD1 automatically charges the filter capacitor C2, the voltage on the second filter capacitor C2 will rise, and due to the first The sum of the voltages on the filter capacitor C1 and the second filter capacitor C2 is always equal to the voltage U ₀ , the first filter capacitor C1 will be in a discharge state, causing the voltage on the first filter capacitor C1 to drop, and the first filter capacitor C1 reaches a steady state The voltage on the second filter capacitor C2 will be equal, so the whole circuit has a good voltage equalization effect.

In a specific embodiment of the present utility model, a set of component parameters can be selected as follows:

Input DC voltage: 550V;

Switching frequency of S1 and S2: 24kHz;

High-frequency transformer turns ratio P1:N1:SD1:SD2:SD3:SD4＝10:11:5:2.5:2.5;

Electrolytic capacitors C1, C2, C3, C4: single 5600μH, 200V;

Resistors R1, R2, R3, R4: 56kΩ, 5.0W;

Diodes D1, D2, D3, D4: 600V, 5A;

Diode D5, D6: 1200V, 5A;

In this embodiment, no complex control circuit is needed, and automatic voltage equalization can be achieved through the function of the auxiliary winding during operation. It has the characteristics of compact structure and good voltage equalization effect, and can be used in practical applications such as half-bridge inverter plasma cutting machines. .

The capacitor series voltage equalizing circuit proposed by the utility model, when the capacitor has uneven terminal voltage due to capacitance or leakage current, charges and discharges the filter capacitor with uneven terminal voltage through the auxiliary winding to make each filter capacitor The terminal voltages are equal. Moreover, the circuit proposed by the utility model does not need an additional control circuit, which greatly saves the cost and has a good voltage equalizing effect.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions of the present utility model will be obvious to those skilled in the art after reading the above content. Therefore, the protection scope of the present utility model should be defined by the appended claims.

Claims (8)

1. a kind of capacitor series average-voltage circuit, which is characterized in that including half-bridge inversion circuit and high frequency transformer circuit；

The half-bridge inversion circuit includes the filter capacitor bridge arm being parallel between DC power anode, negative terminal, equalizing resistance bridge Arm, diode bridge arm and IGBT bridge arms, to complete the power conversion of DC-AC；

The high frequency transformer circuit includes primary side winding and vice-side winding, and high frequency transformer is additionally provided with three auxiliary windings, and three The both ends of a auxiliary winding are separately connected the filter capacitor bridge arm, the equalizing resistance bridge arm, for being responsible for filtered electrical Hold the pressure of each filter capacitor in bridge arm；

Filter capacitor in the half-bridge inversion circuit occur terminal voltage it is unequal when, the auxiliary winding of the high frequency transformer is logical It crosses to couple with the primary side winding and generates induced voltage, be that the unequal filter capacitor of terminal voltage carries out charge and discharge so that each filter Terminal voltage on wave capacitance is equal.

2. capacitor series average-voltage circuit according to claim 1, which is characterized in that the half-bridge inversion circuit includes： First~the 4th filter capacitor, the first~the 4th equalizing resistance, the first~the 6th diode, the first~the 2nd IGBT；

The high frequency transformer circuit include primary side winding, vice-side winding and be arranged secondary side first~third auxiliary around Group；

The half-bridge inversion circuit includes：First~the 4th filter capacitor, the first~the 4th equalizing resistance, the first~the 6th 2 pole Pipe, the first~the 2nd IGBT；

Wherein：

DC power anode and the first filter capacitor anode, first equalizing resistance one end, the first diode cathode, the 5th diode Cathode and the first IGBT drain electrodes are connected；

DC power cathode and the 4th filter capacitor cathode, the 4th equalizing resistance one end, the 4th diode anode, the 6th diode Anode and the 2nd IGBT source electrodes are connected；

First filter capacitor cathode and the second filter capacitor anode, the first equalizing resistance other end, second equalizing resistance one end with And first auxiliary winding Same Name of Ends be connected；

Second filter capacitor cathode and third filter capacitor anode, the second equalizing resistance other end, third equalizing resistance one end, the Two diode anodes, third diode cathode, the second auxiliary winding Same Name of Ends and primary side winding non-same polarity are connected；

Third filter capacitor cathode and the 4th filter capacitor anode, the third equalizing resistance other end, the 4th equalizing resistance other end And third auxiliary winding Same Name of Ends is connected；First diode anode and the second diode cathode and the first auxiliary winding are non-same Name end is connected；

Third diode anode is connected with the 4th diode cathode and third auxiliary winding non-same polarity；5th diode anode It is connected with the 6th diode cathode and the second auxiliary winding non-same polarity；

First IGBT source electrodes drain with the 2nd IGBT and primary side winding Same Name of Ends is connected.

3. capacitor series average-voltage circuit according to claim 2, which is characterized in that the described first~the 4th filter capacitor Capacitance it is equal.

4. capacitor series average-voltage circuit according to claim 2, which is characterized in that the described first~the 4th equalizing resistance Resistance value it is equal.

5. capacitor series average-voltage circuit according to claim 2, which is characterized in that the number of turns of second auxiliary winding With the equal turn numbers of the primary side winding of the high frequency transformer.

6. capacitor series average-voltage circuit according to claim 2, which is characterized in that first auxiliary winding and third The equal turn numbers of auxiliary winding are the half of primary side winding the number of turns of the high frequency transformer.

7. capacitor series average-voltage circuit according to claim 2, which is characterized in that the first IGBT, the 2nd IGBT Built-in anti-paralleled diode.

8. according to claim 1-6 any one of them capacitor series average-voltage circuits, which is characterized in that the high frequency transformer Primary side winding and vice-side winding equal turn numbers.