A three-phase inverter transistor negative voltage turn-off circuit

Abstract

This invention provides a three-phase inverter transistor negative voltage shutdown circuit, which consists of a PWM control circuit, a push-pull circuit, an isolation transformer circuit, a voltage doubler rectifier circuit, and a voltage regulator output circuit connected in sequence. The PWM control circuit drives the push-pull circuit, which mainly consists of transistors Q1 and Q2. The input of the push-pull circuit is connected to the driving power supply of the three-phase inverter MOSFETs, and the output is connected to the primary side of four transformers. The secondary side of the transformers is connected to a voltage doubler rectifier circuit composed of diodes and capacitors. The midpoint of the series connection of two capacitors in the voltage doubler rectifier circuit is taken as the zero-level point of the three-phase upper transistors of the three-phase inverter. The outputs of three of the transformers are used as the driving power supply for the three-phase upper transistors of the three-phase inverter, and the three lower transistors share a common ground, with the output of the remaining transformer serving as the driving power supply for the lower transistors. Different Zener diodes can be selected to achieve the required negative voltage level. This circuit has the advantages of high flexibility, strong versatility, low cost, and simple circuit structure.

Description

Technical Field

[0001] This utility model relates to the field of electronic power technology, and in particular to a transistor negative voltage turn-off circuit for a three-phase inverter. Background Technology

[0002] In a three-phase inverter, when the down transistor turns on, it pulls up the gate-source (GS) voltage of the up transistor. In MOSFETs with a low threshold voltage (Vth), this can easily lead to false turn-on, causing a shoot-through between the up and down transistors, potentially resulting in inverter failure. A common solution in current technology is to select MOSFETs with a high Vth voltage, but this increases the power consumption of the drive power supply and the losses of the turn-on MOSFET, causing it to overheat. Currently, circuits incorporating negative voltage turn-off typically use dedicated negative voltage chips, but this significantly increases cost and circuit complexity. For example, Chinese invention patent publication number CN114744857A discloses a method, device, and switching transistor drive control circuit for determining the turn-off negative voltage of a switching transistor. The method for determining the turn-off negative voltage includes: determining a first turn-off negative voltage model and a second turn-off negative voltage model; inputting the obtained turn-off gate resistance, turn-on gate resistance, bus voltage, and minimum turn-on voltage of the switching transistor into the first turn-off negative voltage model to obtain the absolute value of the upper limit of the turn-off negative voltage; inputting the obtained absolute values ​​of the turn-off gate resistance, turn-on gate resistance, bus voltage, and the maximum withstand negative voltage of the switching transistor into the second turn-off negative voltage model to obtain the absolute value of the lower limit of the turn-off negative voltage; and determining the turn-off negative voltage range of the switching transistor based on the absolute values ​​of the upper and lower limits of the turn-off negative voltage. However, the control method for the turn-off negative voltage in this technical solution is relatively complex.

[0003] Therefore, in view of the problems existing in the prior art, it is of great importance to provide a three-phase inverter transistor negative voltage turn-off circuit technology that is highly versatile, low-cost and simple in circuit structure. Utility Model Content

[0004] The purpose of this invention is to avoid the shortcomings of the prior art and provide a three-phase inverter transistor negative voltage shutdown circuit. This circuit constructs a simple forward power supply group to meet the positive and negative voltage required for driving the MOSFETs of the three-phase inverter, thereby improving the reliability of the three-phase inverter and solving the problem of the upper and lower transistors being connected and causing the inverter to fail due to the lower transistor being turned on.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A three-phase inverter transistor negative voltage turn-off circuit, the negative voltage turn-off circuit comprising a PWM control circuit, a push-pull circuit, an isolation transformer circuit, a voltage doubler rectifier circuit, and a voltage regulator output circuit connected in sequence; wherein:

[0007] The output of the PWM control circuit is connected to the push-pull circuit and generates a square wave signal to be output to the push-pull circuit.

[0008] The input terminal of the push-pull circuit is connected to the MOS transistor drive power supply of the three-phase inverter, and the output terminal is connected to the primary side of the transformer of the isolation voltage circuit. The push-pull circuit transmits the received square wave signal to the isolation transformer circuit and improves the transmission efficiency of the square wave signal.

[0009] The isolation transformer circuit includes four sets of transformers. The primary side of each set of transformers is connected to a push-pull circuit, and the secondary side of the transformers is connected to a voltage doubler rectifier circuit. The output terminals of three sets of transformers are configured as the driving power supply for the three-phase upper transistors of the three-phase inverter, and the output terminal of the remaining set of transformers is configured as the driving power supply for the three-phase lower transistors of the three-phase inverter. The three-phase lower transistors share a common ground.

[0010] The voltage doubler rectifier circuit consists of diodes and capacitors. The midpoint of the two series capacitor lines at the output of the voltage doubler rectifier circuit is configured as the zero-level point of the three-phase upper transistor of the three-phase inverter.

[0011] The voltage regulation output circuit includes at least a Zener diode, which is connected in parallel to the output terminal of the voltage doubler rectifier circuit, and a negative voltage cutoff value is set at the positive terminal of the Zener diode.

[0012] The PWM control circuit described above includes a control chip U1. The OUT pin of the control chip U1 is connected to a push-pull circuit, the VCC pin is connected to the three-phase inverter MOSFET drive power supply, the GND pin is grounded, and the remaining pins are connected to the peripheral circuit.

[0013] Preferably, the control chip U1 is model UC2845BD1.

[0014] The push-pull circuit described above includes transistors Q1 and Q2, resistors R165 and R175, diode DF21, and capacitors C104 and CA16; wherein transistor Q1 is an NPN transistor and Q2 is a PNP transistor; the bases of transistors Q1 and Q2 are connected to resistors R165 and R175 respectively, the other end of resistor R175, the anode of diode DF21, and the collector of transistor Q2 are all grounded, and resistor R1... The other end of 65 and the negative terminal of diode DF21 are both connected to the output terminal of the PWM control circuit; the collector of transistor Q1 serves as the input terminal of the push-pull circuit and is connected to the three-phase inverter MOS transistor drive power supply; one end of the line formed by capacitors C104 and CA16 in parallel is connected to the three-phase inverter MOS transistor drive power supply, and the other end is grounded; the emitters of transistors Q1 and Q2 are connected, and the lead of this connection serves as the output terminal of the push-pull circuit and is connected to the isolation transformer circuit.

[0015] Preferably, the transistor Q1 is a PBSS4350Z and the transistor Q2 is a PBSS5350Z.

[0016] Preferably, the transformer in the isolation transformer circuit is a transformer with a turns ratio of 1:1, so that the transformer can perform the isolation function.

[0017] The voltage doubler rectifier circuit described above has four sub-circuits with the same structure. Each sub-circuit of the voltage doubler rectifier circuit is connected to the output terminal of each transformer in the isolation transformer circuit. The sub-circuit of the voltage doubler rectifier circuit includes capacitors C73, C76, C84, C75, and C99, as well as voltage doubler diodes DF11 and DF18. The positive terminal of voltage doubler diode DF11 and the negative terminal of DF18 are connected together and then connected to capacitor C73. The other end of capacitor C73 is connected to the positive terminal of the transformer output, and the positive terminal of diode DF18 is connected to the negative terminal of the transformer output. Capacitor C76 is connected in parallel between the negative terminal of voltage doubler diode DF11 and the positive terminal of DF18. Capacitor C84 is connected in parallel across capacitor C76. Capacitors C75 and C99 are connected in series and then in parallel across capacitor C84. The midpoint lead of the series circuit of capacitors C75 and C99 is taken as the zero-level point of the three-phase upper transistor of the three-phase inverter, and the two ends of the series circuit are used as the output terminals connected to the voltage regulation output circuit.

[0018] Preferably, the voltage multiplier diode is model IN4148.

[0019] The voltage regulation output circuit described above includes four sub-circuits with the same structure. Each sub-circuit of the voltage regulation output circuit is connected to the output terminal of the sub-circuit of the isolation transformer circuit. The sub-circuit of the voltage regulation output circuit consists of a resistor R159 and a Zener diode DZ1 connected in series. The negative terminal of the Zener diode DZ1 is connected to the resistor R159, and the positive terminal of the Zener diode DZ1 and the other end of the resistor R159 are connected in parallel to the output terminal of the isolation transformer circuit. The line containing the positive terminal of the Zener diode DZ1 serves as the interface for setting the negative voltage cutoff value, and the line containing the other end of the resistor R159 serves as the driving power supply for the upper or lower three-phase transistors of the three-phase inverter.

[0020] Preferably, the Zener diode has a Zener voltage of 5V, a negative voltage cutoff voltage of -5V, and the output voltage of the three-phase inverter MOSFET drive power supply is 20V.

[0021] The beneficial effects of this utility model are:

[0022] This invention provides a three-phase inverter transistor negative voltage shutdown circuit, which consists of a PWM control circuit, a push-pull circuit, an isolation transformer circuit, a voltage doubler rectifier circuit, and a voltage regulator output circuit connected in sequence. The PWM control circuit drives the push-pull circuit, which mainly consists of transistors Q1 and Q2. The input of the push-pull circuit is connected to the driving power supply of the three-phase inverter MOSFETs, and the output is connected to the primary side of four transformers. The secondary side of the transformers is connected to a voltage doubler rectifier circuit composed of diodes and capacitors. The midpoint of the series connection of two capacitors in the voltage doubler rectifier circuit is taken as the zero-level point of the three-phase upper transistors of the three-phase inverter. Furthermore, the outputs of three of the transformers are used as the driving power supply for the three-phase upper transistors of the three-phase inverter, while the three lower transistors share a common ground, with the output of the remaining transformer serving as the driving power supply for the lower transistors. Different Zener diodes can be selected to achieve the required negative voltage level. This circuit has the advantages of high flexibility, strong versatility, low cost, and simple circuit structure. Attached Figure Description

[0023] Figure 1 A circuit module structure diagram of the negative pressure shutdown circuit provided by this utility model;

[0024] Figure 2 The circuit structure diagram of the negative pressure shutdown circuit provided by this utility model. Detailed Implementation

[0025] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0026] like Figure 1-2As shown, this embodiment provides a three-phase inverter transistor negative voltage turn-off circuit. The negative voltage turn-off circuit includes a PWM control circuit, a push-pull circuit, an isolation transformer circuit, a voltage doubler rectifier circuit, and a voltage regulator output circuit connected in sequence. The output terminal of the PWM control circuit is connected to the push-pull circuit and generates a square wave signal, which is output to the push-pull circuit. The input terminal of the push-pull circuit is connected to the three-phase inverter MOSFET drive power supply, and the output terminal is connected to the primary side of the transformer in the isolation voltage circuit. The push-pull circuit transmits the received square wave signal to the isolation transformer circuit and improves the transmission efficiency of the square wave signal. The isolation transformer circuit includes four sets of transformers T1, T2, T3, and T4. The primary side of each set of transformers (T1 / T2 / T3 / T4) is connected to the push-pull circuit. The secondary sides of transformers 2 / T3 / T4 are respectively connected to the corresponding sub-circuits of the voltage doubler rectifier circuit; and the output terminals of three sets of transformers T1, T2, and T3 are configured as the driving power supply for the three-phase upper transistors of the three-phase inverter, while the output terminal of the remaining set of transformers T4 is configured as the driving power supply for the three-phase lower transistors of the three-phase inverter, and the three lower transistors share a common ground; the voltage doubler rectifier circuit consists of four sub-circuits with the same structure, each of which consists of diodes and capacitors, and the midpoint of the two series capacitor lines at the output terminal of the voltage doubler rectifier circuit sub-circuit is configured as the zero-level point of the three-phase upper transistors of the three-phase inverter; the voltage regulation output circuit includes four sub-circuits with the same structure, each of which is equipped with a Zener diode, which is connected in parallel at the output terminal of the voltage doubler rectifier circuit, and a negative voltage cutoff voltage value is set at the positive terminal of the Zener diode.

[0027] In this embodiment, the PWM control circuit includes a control chip U1, model UC2845BD1. The OUT pin of the control chip U1 is connected to a push-pull circuit, the VCC pin is connected to the three-phase inverter MOSFET drive power supply, the GND pin is grounded, and the remaining COMP, VFB, ISENSE, RT / CT, and VREF pins are connected to external circuits. The control chip U1 is equipped with a 255kHz square wave generator, which outputs a 50% duty cycle square wave signal to the push-pull circuit. The output voltage of the three-phase inverter MOSFET drive power supply is 20V.

[0028] In this embodiment, the push-pull circuit includes transistors Q1 and Q2, resistors R165 and R175, diode DF21, and capacitors C104 and CA16; wherein, transistor Q1 is an NPN transistor and Q2 is a PNP transistor; the bases of transistors Q1 and Q2 are connected to resistors R165 and R175 respectively, and the other end of resistor R175, the anode of diode DF21, and the collector of transistor Q2 are all grounded. The other end of 165 and the negative terminal of diode DF21 are both connected to the output terminal of the PWM control circuit; the collector of transistor Q1 serves as the input terminal of the push-pull circuit and is connected to the three-phase inverter MOSFET drive power supply; one end of the parallel line of capacitors C104 and CA16 is connected to the three-phase inverter MOSFET drive power supply, and the other end is grounded; the emitters of transistors Q1 and Q2 are connected, and the lead of this connection serves as the output terminal of the push-pull circuit and is connected to the isolation transformer circuit. Specifically, NPN and PNP transistors are selected for large circuit applications; transistor Q1 is a PBSS4350Z, and transistor Q2 is a PBSS5350Z.

[0029] In this embodiment, the transformer of the isolation transformer circuit is a transformer with a turns ratio of 1:1, so that the transformer can play an isolation role.

[0030] In this embodiment, the voltage doubler rectifier circuit has four sub-circuits with the same structure. Each sub-circuit of the voltage doubler rectifier circuit is connected to the output terminals of each group of transformers T1, T2, T3, and T4 of the isolation transformer circuit. The sub-circuit of the voltage doubler rectifier circuit includes capacitors C73 (or C102 / C116 / C141), C76 (or C106 / C118 / C143), C84 (or C111 / C120 / C144), C75 (or C105 / C117 / C142), C99 (or C113 / C123 / C146), and voltage doubler diodes DF11 (or DF19 / DF22 / DF24), DF1... 8 (or DF20 / DF23 / DF25), wherein the positive terminal of voltage multiplier diode DF11 and the negative terminal of DF18 are connected together and then connected to capacitor C73; the other end of capacitor C73 is connected to the positive terminal of transformer output, and the positive terminal of diode DF18 is connected to the negative terminal of transformer output; capacitor C76 is connected in parallel between the negative terminal of voltage multiplier diode DF11 and the positive terminal of DF18; capacitor C84 is connected in parallel across capacitor C76; capacitors C75 and C99 are connected in series and then in parallel across capacitor C84; the midpoint lead of the series circuit of capacitors C75 and C99 is taken as the zero-level point U of the three-phase upper transistor of the three-phase inverter; and the two ends of the series circuit of C75 and C99 are used as the output terminals connected to the voltage regulation output circuit. Similarly, in other sub-circuits, the midpoint lead of the series connection between capacitors C105 and C113 is taken as the zero-level point V of the three-phase upper transistor of the three-phase inverter, and the midpoint lead of the connection between capacitors 117 and 123 is taken as the zero-level point W of the three-phase upper transistor of the three-phase inverter. The aforementioned voltage multiplier diodes are all IN4148.

[0031] It should be noted that the labels of capacitors and voltage multiplier diodes in the sub-circuits of the voltage multiplier rectifier circuit are for the convenience of describing the circuit only, and are not limited to components with specific labels. Capacitor C73 is the same component as capacitors C102, C116, and C141 in other sub-circuits with the same structure; voltage multiplier diode DF11 is the same component as DF19, DF22, and DF24 in other sub-circuits with the same structure; voltage multiplier diode DF18 is the same component as DF20, DF23, and DF25 in other sub-circuits with the same structure, and so on.

[0032] In this embodiment, the voltage regulation output circuit includes four sub-circuits with identical structures. Each sub-circuit of the voltage regulation output circuit is connected to the output terminal of the sub-circuit of the isolation transformer circuit. The sub-circuit of the voltage regulation output circuit consists of a resistor R159 (or R164 / R177 / R204) and a Zener diode DZ1 (or DZ3 / DZ4 / DZ5) connected in series. The cathode of the Zener diode DZ1 is connected to the resistor R159, and the anode of the Zener diode DZ1 and the other end of the resistor R159 are connected in parallel to the isolation transformer. The output terminal of the sub-circuit of the circuit (i.e., connected in parallel across the series circuit of capacitors C75 and C99); the line containing the positive terminal of the Zener diode DZ1 (or DZ3 / DZ4 / DZ5) serves as the interface for setting the negative voltage cutoff value, which is set to -5V; furthermore, the line containing the other end of resistor R159 (or R164 / R177) in three of the sub-circuits serves as the power supply for driving the three-phase upper transistors of the three-phase inverter, and the line containing the other end of resistor R204 in the remaining sub-circuit serves as the power supply for driving the three-phase lower transistors of the three-phase inverter. The Zener diode's voltage regulation value is 5V.

[0033] It should be noted that the labels of resistors and Zener diodes in the sub-circuits of the voltage regulation output circuit are for illustrative purposes only and are not intended to be specific to any particular component. Resistor R159 is the same component as R164, R177, and R204 in other sub-circuits with the same structure, and Zener diode DZ1 is the same component as DZ3, DZ4, and DZ5 in other sub-circuits with the same structure.

[0034] The working principle of this embodiment is as follows: In a three-phase inverter system requiring a 15V three-phase inverter MOSFET drive power supply voltage and a -5V negative voltage turn-off voltage, the three-phase inverter MOSFET drive power supply is +20V_P, i.e., 20V. The control chip U1 is a TI chip of model UCC28C43, configured as a 255kHz square wave generator outputting a square wave signal with a 50% duty cycle, and peripheral circuitry is configured. Transistors Q1 and Q2 are both power devices, using a combination of high-current NPN and PNP transistors, specifically models PBSS4350Z and PBSS5350Z. Transformers T1, T2, T3, and T4 are selected with a 1:1 turns ratio for isolation, resulting in a forward converter power supply configuration. The secondary side of the transformer is connected to a voltage multiplier circuit consisting of capacitors and two voltage multiplier diodes. Capacitors C86, C73, C112, C102, C122, C116, C145, and C141 are selected as 1uF capacitors. Voltage multiplier diodes DF11, DF18, DF19, DF20, DF22, DF23, DF24, and DF25 are selected as 1N4148 diodes. The output power supply voltage per phase, Vout, is 20V * 0.5 * 2 = 20V. The voltage regulation value of Zener diodes DZ1, DZ3, DZ4, and DZ5 is selected as 5V. The drive voltage of the upper diode in each phase is 15V, and the turn-off voltage is -5V, which meets the negative voltage turn-off requirement.

[0035] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the utility model should also fall within the protection scope of the claims of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A transistor negative voltage turn-off circuit for a three-phase inverter, characterized in that, The negative pressure shutdown circuit includes a PWM control circuit, a push-pull circuit, an isolation transformer circuit, a voltage doubler rectifier circuit, and a voltage regulator output circuit connected in sequence; wherein: The output of the PWM control circuit is connected to the push-pull circuit and generates a square wave signal to be output to the push-pull circuit. The input terminal of the push-pull circuit is connected to the MOS transistor drive power supply of the three-phase inverter, and the output terminal is connected to the primary side of the transformer of the isolation voltage circuit. The push-pull circuit transmits the received square wave signal to the isolation transformer circuit and improves the transmission efficiency of the square wave signal. The isolation transformer circuit includes four sets of transformers. The primary side of each set of transformers is connected to a push-pull circuit, and the secondary side of the transformers is connected to a voltage doubler rectifier circuit. The output terminals of three sets of transformers are configured as the driving power supply for the three-phase upper transistors of the three-phase inverter, and the output terminal of the remaining set of transformers is configured as the driving power supply for the three-phase lower transistors of the three-phase inverter. The three-phase lower transistors share a common ground. The voltage doubler rectifier circuit consists of diodes and capacitors. The midpoint of the two series capacitor lines at the output of the voltage doubler rectifier circuit is configured as the zero-level point of the three-phase upper transistor of the three-phase inverter. The voltage regulation output circuit includes at least a Zener diode, which is connected in parallel to the output terminal of the voltage doubler rectifier circuit, and a negative voltage cutoff value is set at the positive terminal of the Zener diode.

2. The negative voltage shutdown circuit according to claim 1, characterized in that, The PWM control circuit includes a control chip U1. The OUT pin of the control chip U1 is connected to a push-pull circuit, the VCC pin is connected to the three-phase inverter MOSFET drive power supply, the GND pin is grounded, and the remaining pins are connected to the peripheral circuit.

3. The negative voltage shutdown circuit according to claim 2, characterized in that, The control chip U1 is model UC2845BD1.

4. The negative voltage shutdown circuit according to claim 1, characterized in that, The push-pull circuit includes transistors Q1 and Q2, resistors R165 and R175, diode DF21, and capacitors C104 and CA16. Transistor Q1 is an NPN transistor, and Q2 is a PNP transistor. The bases of transistors Q1 and Q2 are connected to resistors R165 and R175 respectively. The other end of resistor R175, the anode of diode DF21, and the collector of transistor Q2 are all grounded. The other end of resistor R165 and the cathode of diode DF21 are both connected to the output of the PWM control circuit. The collector of transistor Q1 serves as the input of the push-pull circuit and is connected to the three-phase inverter MOSFET drive power supply. One end of the parallel connection of capacitors C104 and CA16 is connected to the three-phase inverter MOSFET drive power supply, and the other end is grounded. The emitters of transistors Q1 and Q2 are connected, and this connection line serves as the output of the push-pull circuit and is connected to the isolation transformer circuit.

5. The negative voltage shutdown circuit according to claim 4, characterized in that, The transistor Q1 is a PBSS4350Z and the transistor Q2 is a PBSS5350Z.

6. The negative voltage shutdown circuit according to claim 1, characterized in that, The transformer in the isolation transformer circuit is a transformer with a turns ratio of 1:

1.

7. The negative voltage shutdown circuit according to claim 1, characterized in that, The voltage doubler rectifier circuit has four sub-circuits with the same structure. Each sub-circuit of the voltage doubler rectifier circuit is connected to the output terminal of each transformer in the isolation transformer circuit. The sub-circuit of the voltage doubler rectifier circuit includes capacitors C73, C76, C84, C75, and C99, and voltage doubler diodes DF11 and DF18. The positive terminal of voltage doubler diode DF11 and the negative terminal of DF18 are connected together and then connected to capacitor C73. The other end of capacitor C73 is connected to the positive terminal of the transformer output, and the positive terminal of diode DF18 is connected to the negative terminal of the transformer output. Capacitor C76 is connected in parallel with the negative terminal of voltage doubler diode DF11 and the positive terminal of DF18. Capacitor C84 is connected in parallel across capacitor C76. Capacitors C75 and C99 are connected in series and then in parallel across capacitor C84. The midpoint lead of the series line of capacitors C75 and C99 is taken as the zero-level point of the three-phase upper transistor of the three-phase inverter. The two ends of the series line are used as the output terminals connected to the voltage regulation output circuit.

8. The negative voltage shutdown circuit according to claim 7, characterized in that, The voltage multiplier diode is model number IN4148.

9. The negative voltage shutdown circuit according to claim 1, characterized in that, The voltage regulation output circuit includes four sub-circuits with the same structure. Each sub-circuit of the voltage regulation output circuit is connected to the output terminal of the sub-circuit of the isolation transformer circuit. The sub-circuit of the voltage regulation output circuit consists of a resistor R159 and a Zener diode DZ1 connected in series. The negative terminal of the Zener diode DZ1 is connected to the resistor R159, and the positive terminal of the Zener diode DZ1 and the other end of the resistor R159 are connected in parallel to the output terminal of the isolation transformer circuit. The line containing the positive terminal of the Zener diode DZ1 serves as the interface for setting the negative voltage cutoff value, and the line containing the other end of the resistor R159 serves as the driving power supply for the upper or lower three-phase transistors of the three-phase inverter.

10. The negative voltage shutdown circuit according to claim 9, characterized in that, The Zener diode has a Zener voltage of 5V and a negative voltage cutoff voltage of -5V. The output voltage of the three-phase inverter MOSFET drive power supply is 20V.

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