Parallel IGBT current sharing control circuit

Abstract

The invention relates to a parallel IGBT current sharing control circuit, and belongs to the field of power electronic devices. Decoupling of gate driving voltage and emitter driving voltage of parallel IGBTs is achieved through the decoupling circuit, the output end of the decoupling circuit is connected with the input end of the push-pull circuit, and one controllable switch tube in the push-pull circuit is connected to a gate of a corresponding IGBT tube through a gate opening resistor. And the other controllable switch tube is connected to the gate pole of the corresponding IGBT tube through a gate pole turn-off resistor, and synchronism of turn-on and turn-off control of each parallel IGBT module is realized by ensuring that the resistance value of the gate pole turn-on resistor in each push-pull circuit is the same as the resistance value of the gate pole turn-off resistor. The problem that in the prior art, due to the fact that emitting electrode parasitic inductance is inconsistent, all branches of parallel IGBTs are not uniform in current is solved.

Description

Technical Field

[0001] The invention relates to a parallel IGBT current sharing control circuit, belonging to the field of power electronic devices. Background Art

[0002] As the core component in energy storage systems, the status of IGBTs during application is closely monitored. In large-capacity application environments, the rated current of a single IGBT device cannot meet the design requirements, so IGBTs need to be used in parallel.

[0003] When using IGBTs in parallel, it is necessary to ensure that the on-off state and current sharing capability of each IGBT are consistent. However, due to factors such as mismatched parameters of individual devices, asymmetric copper busbar structure, and differences in heat dissipation conditions, the current stress on the parallel IGBTs is not balanced, and the on-off state of the IGBTs cannot be kept consistent.

[0004] Chinese patent publication CN205430040U discloses a drive control circuit for three parallel IGBTs in electric vehicles. This circuit ensures symmetry and stability of the three-phase output of the three parallel IGBTs through a push-pull circuit that receives PWM drive pulses, a current balancing circuit, and an overvoltage balancing protection circuit. However, this circuit fails to reduce the parasitic inductance of the IGBT emitters, which can lead to uneven current distribution among the three parallel IGBT branches. Summary of the Invention

[0005] The purpose of the present invention is to provide a parallel IGBT current sharing control circuit to solve the problem of uneven current sharing among branches of the parallel IGBTs caused by inconsistent emitter parasitic inductance in the prior art.

[0006] To achieve the above object, the solution of the present invention includes:

[0007] A parallel IGBT current sharing control circuit of the present invention includes a control branch for controlling each parallel IGBT module, each control branch includes an upper tube control branch and a lower tube control branch, each upper tube control branch and lower tube control branch includes a decoupling circuit and a push-pull circuit, the input end of the decoupling circuit is used to connect the gate drive voltage and emitter drive voltage of the IGBT tube to achieve decoupling of the gate drive voltage and emitter drive voltage of the IGBT tube, the output end of the decoupling circuit is connected to the input end of the push-pull circuit, one controllable switch tube in the push-pull circuit is used to connect to the gate of the corresponding IGBT tube through a gate turn-on resistor, and the other controllable switch tube is used to connect to the gate of the corresponding IGBT tube through a gate turn-off resistor, the resistance value of the gate turn-on resistor in each push-pull circuit is the same as the resistance value of the gate turn-off resistor, so as to achieve synchronization of the turn-on and turn-off control of each parallel IGBT module.

[0008] Furthermore, the decoupling circuit includes a common-mode inductor and a bidirectional voltage regulator. The input end of the common-mode inductor is used to connect to the gate drive voltage signal end and the emitter drive voltage signal end respectively. The output end of the common-mode inductor is connected to both ends of the bidirectional voltage regulator. The output end of the bidirectional voltage regulator is connected to the input end of the push-pull circuit.

[0009] Furthermore, the decoupling circuit also includes a filter circuit, which is arranged between the common-mode inductor and the bidirectional voltage regulator.

[0010] Furthermore, the decoupling circuit further includes a voltage divider circuit, which is used to divide the emitter drive voltage signal, and the divided signal is connected to the input end of the common mode inductor.

[0011] Furthermore, the push-pull circuit includes a first emitter resistor and a second emitter resistor of the IGBT tube, the controllable switch tube connected to the gate turn-on resistor is the first controllable switch tube, and the controllable switch tube connected to the gate turn-off resistor is the second controllable switch tube; one end of the first emitter resistor of the IGBT tube is used to connect to the auxiliary emitter drive voltage, and the other end is connected to the gate turn-on resistor; one end of the second emitter resistor of the IGBT tube is used to connect to COMT, and the other end is connected to the gate turn-off resistor; the first controllable switch tube is arranged between the first emitter resistor and the gate turn-on resistor; the second controllable switch tube is arranged between the second emitter resistor and the gate turn-off resistor; the control end of the first controllable switch tube and the control end of the second controllable switch tube are connected to the two ends of the bidirectional voltage regulator tube.

[0012] Furthermore, the emitter resistor is also connected to the emitter of the IGBT tube.

[0013] Furthermore, a first current limiting resistor is provided between the control end of the first controllable switch tube of the push-pull circuit and the bidirectional voltage regulator tube, and a second current limiting resistor is provided between the control end of the second controllable switch tube of the push-pull circuit and the bidirectional voltage regulator tube.

[0014] Furthermore, the controllable switch tube is a triode.

[0015] The beneficial effects of the present invention are as follows: as an improved invention, the present invention includes a control branch for controlling each parallel IGBT module, each control branch includes an upper tube control branch and a lower tube control branch, each upper tube control branch and lower tube control branch includes a decoupling circuit and a push-pull circuit, the input end of the decoupling circuit is connected to the gate drive voltage and emitter drive voltage of the IGBT, and the inconsistency of the emitter parasitic inductance is weakened by decoupling the gate drive voltage and the emitter drive voltage of the IGBT; the output end of the decoupling circuit is connected to the input end of the push-pull circuit, one controllable switch tube of the push-pull circuit is connected to the gate of the corresponding IGBT through a gate turn-on resistor, and the other controllable switch tube is connected to the gate of the corresponding IGBT tube through a gate turn-off resistor, the resistance value of the gate turn-on resistor in each push-pull circuit is the same as the resistance value of the gate turn-off resistor, so as to ensure the consistency of turning on and off of each parallel IGBT module. Therefore, the present invention solves the problem of uneven current distribution in each branch of the parallel IGBT caused by inconsistent emitter parasitic inductance in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the schematic diagram of the three-parallel IGBT drive circuit;

[0017] Figure 2 It is a specific waveform diagram of the implementation. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below in detail with reference to the accompanying drawings and embodiments.

[0019] The concept of the present invention is to achieve decoupling of the gate drive voltage and emitter drive voltage of the parallel IGBT through a decoupling circuit, thereby weakening the inconsistency of the emitter parasitic inductance and improving the current sharing effect.

[0020] Parallel IGBT current sharing control circuit embodiment:

[0021] like Figure 1 The schematic diagram of the three-parallel IGBT drive control circuit shown in FIG. 1 includes a control branch for controlling each parallel IGBT module. Each control branch includes an upper tube control branch and a lower tube control branch. The gate turn-off resistance directly affects the switching speed and dynamic characteristics of the IGBT. If the turn-off resistance of each module is different, it will lead to inconsistent switching speeds, which in turn affects the current distribution. Simply adding a decoupling circuit without ensuring the consistency of the gate turn-off resistance cannot effectively improve the current sharing effect. It is necessary to optimize the decoupling circuit and ensure the consistency of the gate turn-off resistance at the same time to achieve better current sharing. Figure 1As shown, each upper tube control branch and lower tube control branch includes a decoupling circuit and a push-pull circuit. The input end of the decoupling circuit is respectively connected to the gate drive voltage GA and the emitter drive voltage VEA of the IGBT to achieve decoupling of the IGBT gate drive voltage and the emitter drive voltage. The output end of the decoupling circuit is connected to the input end of the push-pull circuit. There are two controllable switching tubes (triodes in this embodiment) in the push-pull circuit. One controllable switching tube is connected to the gate of the corresponding IGBT tube through a gate turn-on resistor, and the other controllable switching tube is connected to the gate of the corresponding IGBT tube through a gate turn-off resistor to achieve on and off control of the IGBT tube. In order to ensure the consistency of the gate drive circuit parameters of each IGBT tube and achieve better current sharing effect, the resistance value of the gate turn-on resistor in each push-pull circuit is the same as the resistance value of the gate turn-off resistor.

[0022] Specifically, taking the upper tube control branch of the first IGBT power module as an example, the decoupling circuit mainly includes a common-mode inductor L11 and a bidirectional voltage regulator (TVS bidirectional diode in this embodiment) D13. The input terminal 1 of the common-mode inductor is connected to the emitter drive voltage signal terminal VEA, and the input terminal 3 of the common-mode inductor is connected to the gate drive voltage signal terminal GA. The output terminals 2 and 4 of the common-mode inductor are connected to the two ends of the TVS bidirectional diode D13, and the output terminal of the TVS bidirectional diode is connected to the input terminal of the push-pull circuit. The common-mode inductor decouples the IGBT gate and emitter, suppressing the power-mode current generated by the interference electromagnetic field between the line and ground loop, as well as the common-mode voltage generated by the power-mode current on the load, thereby weakening the impact of inconsistent emitter parasitic inductance, thereby ensuring the consistency of the IGBT gate signal.

[0023] To prevent the input voltage of the common-mode inductor from being too large, a voltage divider circuit is further provided between the emitter drive voltage signal terminal and the common-mode inductor. The voltage divider circuit is composed of voltage divider resistors R11, R12 and a diode D11, which is used to divide the emitter drive voltage signal. The function of diode D11 is to prevent reverse connection: when the reverse voltage exceeds the forward conduction voltage of the diode, the diode turns on, forming a low-impedance path, clamping the voltage within a safe range (such as 0.7V). This clamping effect can effectively prevent overvoltage from damaging sensitive components in subsequent circuits, thereby improving the reliability and safety of the circuit. There are many common voltage divider circuits, such as resistor voltage divider circuits (most commonly used), capacitor voltage divider circuits (for AC signals), inductor voltage divider circuits (for high-frequency circuits), etc. The present invention uses a voltage divider circuit composed of diodes and resistors. In order to remove interference and improve signal quality, a filter circuit is also provided between the common-mode inductor and the TVS bidirectional diode D13. In this embodiment, the filter circuit is composed of C13 and R17.

[0024] The push-pull circuit primarily includes the IGBT's first emitter resistor R11', second emitter resistor R111', transistor Q11 (also called the first controllable switch) that controls the IGBT's turn-on, transistor Q12 (also called the second controllable switch) that controls the IGBT's turn-off, a gate-turn-on resistor formed by the parallel connection of resistors R13', R15', and R17', and a gate-turn-off resistor formed by the parallel connection of resistors R14', R16', and R18'. In the figure, first emitter resistor R11' has one end connected to the auxiliary emitter drive voltage VET and the other end to the collector of transistor Q11. Furthermore, first emitter resistor R11' is also connected to the emitter of the corresponding IGBT. Second emitter resistor R111' has one end connected to COMT and the other end to the collector of transistor Q12. COMT is a common-mode signal, representing the average of the two output signals in the push-pull circuit. Its function is to monitor the symmetry of the output signals and ensure that the two transistors operate in the same state. In addition, a second emitter resistor R111' is connected to the emitter of the corresponding IGBT. The emitter of transistor Q11 is connected to the gate of the corresponding IGBT via a gate-on resistor, and the base control terminal of transistor Q11 is connected to the bidirectional diode D13 of the decoupling module. The emitter of transistor Q12 is connected to the gate of the corresponding IGBT via a gate-off resistor, and the base control terminal of transistor Q12 is connected to the bidirectional diode D13 of the decoupling module. Emitter resistor R11' suppresses emitter circulating current, thereby ensuring consistent gate turn-off of the parallel IGBTs. R11' is the emitter resistor of the NPN transistor in the push-pull circuit, which balances the current of the two IGBTs and makes their turn-off process more consistent. When one IGBT turns off more slowly, the voltage drop across the emitter resistor increases, accelerating its turn-off process and making the turn-off times of the two IGBTs more consistent. R111' is also an emitter resistor, providing current balancing. During the drive process, the voltage drop across the emitter resistor is fed back to the base, automatically adjusting the conduction level of the upper and lower transistors (NPN and PNP) in the push-pull circuit, aligning their currents and preventing current imbalance caused by inconsistent transistor parameters. Alternatively, the transistor can be replaced by other controllable switching transistors, such as MOSFETs and IGBTs. The specific choice depends on the application scenario and performance requirements.

[0025] To prevent the decoupling circuit from outputting excessive current, the push-pull module also includes a current-limiting circuit, which consists of current-limiting resistors R19', R110', and R10. The current-limiting resistor R19' is arranged between the control terminal of the transistor Q11 and the bidirectional diode D13. The current-limiting resistor R110' is arranged between the control terminal of the transistor Q12 and the bidirectional diode D13. The current-limiting resistor R10 needs to be connected to the front stage of the push-pull circuit and then to the IGBT gate stage.

[0026] In this embodiment, the decoupling module and push-pull module of the lower tube control branch of the first IGBT power module are similar to the decoupling module and push-pull module of the upper tube control branch of the first IGBT power module, and will not be repeated here. Similarly, the decoupling modules and push-pull modules of the upper and lower tube control branches of the second and third IGBT power modules are similar to the decoupling modules and push-pull modules of the upper and lower tube control branches of the first IGBT power module, and will not be repeated here. It should be noted that during the control process, in order to achieve a better current sharing effect, it is necessary to ensure that the gate turn-on resistance of the three parallel IGBT modules is the same, and the gate turn-off resistance of the three IGBT tubes is the same, so as to achieve synchronization of the turn-on and turn-off control of each parallel IGBT module. The same gate-level turn-on resistance of the upper and lower tubes means that the gate-level turn-on resistance of the upper and lower tubes is the same. As another embodiment, the present invention is applicable to dual parallel IGBT modules or more than three parallel IGBT modules. Regardless of the number of parallel IGBT modules, it is only necessary to ensure that the gate turn-on resistance and gate turn-off resistance of each IGBT module are the same.

[0027] VISOA1 is the input voltage signal to the amplifier in the decoupling circuit. It typically comes from a pre-stage circuit or sensor. After processing by the decoupling circuit, it is input to the amplifier for amplification or further processing. R16 and R15 are used to filter high-frequency noise and stabilize the voltage. R14, C11, and C12 filter high-frequency noise and improve signal quality. VISOT is the voltage input shutdown threshold, which monitors the input voltage to ensure it is within a safe range. When the input voltage exceeds or falls below the set threshold, VISOT triggers shutdown to prevent circuit damage. Capacitor C11' provides a local low-impedance path for the emitter, absorbing high-frequency noise or voltage fluctuations and stabilizing the emitter voltage. R12' is a current-limiting resistor that limits the current flowing into VISOT. C12' is used to suppress high-frequency oscillations and reduce electromagnetic interference. COMT is the common-mode signal, which represents the average of the two output signals in the push-pull circuit. Its function is to monitor the symmetry of the output signals and ensure that the two transistors operate in the same state. C13', C14', and R19 absorb the voltage spike generated when Q11 / Q12 turns off, protecting the transistors. C15' and D11' condition the VISOT signal to ensure its stability and prevent current backflow. The specific current sharing process is as follows: Taking the upper tube control branch of the first IGBT power module as an example, the gate drive voltage GA and emitter drive voltage VEA output by the driver chip first pass through the voltage divider circuit, and the divided voltage value is output to the common-mode inductor L11. The voltage passing through the common-mode inductor is then stabilized by the bidirectional TVS diode D13 through the filter circuit and output to the push-pull module. After passing through the current-limiting resistor, it is input to the base of transistors Q11 and Q12 respectively. Among them, the voltage VET is applied to the collector of transistor Q11 through the emitter resistor R11', and then the IGBT gate-level turn-on resistor realizes the IGBT turn-on process. The transistor Q12 and resistors R14', R16', R18', and R111' together form the IGBT turn-off circuit to ensure the reliable shutdown of the IGBT. The gate-level turn-on resistor Ron is composed of R13', R15', and R17' in parallel, and the gate-level turn-off resistor Roff is composed of R14', R16', and R18' in parallel. When selecting parameters, Ron and Roff of different IGBTs must be the same to ensure the consistency of gate-level drive circuit parameters and achieve better current sharing effect.

[0028] The specific three-parallel IGBT current waveform is as follows Figure 2As shown, according to the calculation formula for uneven current: φ = (|Ic1-Iav| + |Ic2-Iav| + |Ic3-Iav| + |Ic4-Iav|) / (Ic1 + Ic2 + Ic3 + Ic4), φ = 4.03%. It can be seen that the present invention has a significant effect on achieving current sharing of three parallel IGBTs. Ic1, Ic2, Ic3, and Ic4 are the currents flowing through the four IGBTs respectively, and Iav is the average value of each current; |Ic1-Iav|, |Ic2-Iav|, |Ic3-Iav|, |Ic4-Iav| represent the absolute deviation of the current of each IGBT from the average current; Ic1+Ic2+Ic3+Ic4 is the total current of all devices. φ is an evaluation index for the current sharing effect. The smaller the value of φ, the more even the current distribution of each device is, and the better the current sharing effect. It can be seen in the test waveform: Ic1 = 650.4A, Ic2 = 598A, Ic3 = 661.4A.

[0029] As other embodiments, the present invention is applicable to dual parallel IGBT modules or more than three parallel IGBT modules. Regardless of the number of parallel IGBT modules, the structure of the current sharing control branch of each IGBT module is the same.

Claims

1. A parallel IGBT current sharing control circuit, characterized in that: It includes a control branch for controlling each parallel IGBT module, each control branch includes an upper tube control branch and a lower tube control branch, each upper tube control branch and lower tube control branch includes a decoupling circuit and a push-pull circuit, the input end of the decoupling circuit is used to connect the gate drive voltage and emitter drive voltage of the IGBT tube to achieve decoupling of the gate drive voltage and emitter drive voltage of the IGBT tube, the output end of the decoupling circuit is connected to the input end of the push-pull circuit, one controllable switch tube in the push-pull circuit is used to connect to the gate of the corresponding IGBT tube through a gate turn-on resistor, and the other controllable switch tube is used to connect to the gate of the corresponding IGBT tube through a gate turn-off resistor. The resistance value of the gate turn-on resistor in each push-pull circuit is the same as the resistance value of the gate turn-off resistor to achieve synchronization of the turn-on and turn-off control of each parallel IGBT module.

2. The parallel IGBT current sharing control circuit according to claim 1, characterized in that: The decoupling circuit includes a common-mode inductor and a bidirectional voltage regulator. The input end of the common-mode inductor is used to be connected to the gate drive voltage signal end and the emitter drive voltage signal end respectively. The output end of the common-mode inductor is connected to the two ends of the bidirectional voltage regulator. The output end of the bidirectional voltage regulator is connected to the input end of the push-pull circuit.

3. The parallel IGBT current sharing control circuit according to claim 2, characterized in that: The decoupling circuit further includes a filter circuit, which is arranged between the common-mode inductor and the bidirectional voltage regulator.

4. The parallel IGBT current sharing control circuit according to claim 2, characterized in that: The decoupling circuit further includes a voltage divider circuit, which is used to divide the emitter drive voltage signal, and the divided signal is connected to the input end of the common mode inductor.

5. The parallel IGBT current sharing control circuit according to claim 1, characterized in that: The push-pull circuit includes a first emitter resistor of the IGBT tube and a second emitter resistor of the IGBT tube, the controllable switch tube connected to the gate turn-on resistor is the first controllable switch tube, and the controllable switch tube connected to the gate turn-off resistor is the second controllable switch tube; One end of the first emitter resistor of the IGBT tube is used to connect to the auxiliary emitter drive voltage, and the other end is connected to the gate turn-on resistor; one end of the second emitter resistor of the IGBT tube is used to connect to COMT, and the other end is connected to the gate turn-off resistor; the first controllable switch tube is arranged between the first emitter resistor and the gate turn-on resistor; the second controllable switch tube is arranged between the second emitter resistor and the gate turn-off resistor; the control end of the first controllable switch tube and the control end of the second controllable switch tube are connected to the two ends of the bidirectional voltage regulator tube.

6. The parallel IGBT current sharing control circuit according to claim 5, characterized in that: The emitter resistor is also connected to the emitter of the IGBT tube.

7. The parallel IGBT current sharing control circuit according to claim 5, characterized in that: A first current limiting resistor is provided between the control end of the first controllable switch tube of the push-pull circuit and the bidirectional voltage regulator tube, and a second current limiting resistor is provided between the control end of the second controllable switch tube of the push-pull circuit and the bidirectional voltage regulator tube.

8. The parallel IGBT current sharing control circuit according to claim 1, characterized in that: The controllable switch tube is a triode.

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