Self-adjusting device and method of active voltage-sharing driving signal in IGBT series circuit

Abstract

A self-adjusting device and method for active voltage equalization drive signals in IGBT series circuits is disclosed, relating to insulated gate bipolar transistor (IGBT) voltage equalization technology to address the problem of poor initiative in dynamic voltage equalization of IGBT series circuits using existing dynamic voltage equalization methods. The invention includes a drive signal generator for generating initial and final drive signals; a drive circuit for amplifying the initial and final drive signals; an RCD buffer circuit for changing the terminal voltage between the collector and emitter of the IGBT; a sampling circuit for acquiring the on / off timing and terminal voltage between the collector and emitter of the IGBT; and a control system for receiving and comparing the sampled signals. If the comparison results are different, an adjustment signal is output; if the comparison results are the same, a working signal is output. The working signal controls the multiple IGBTs connected in series to connect to the application circuit, enabling the application circuit to enter normal operating state. The beneficial effect is strong active voltage equalization.

Description

Technical Field

[0001] This invention relates to the field of voltage equalization technology for insulated gate bipolar transistors, and more particularly to a self-adjusting device and method for active voltage equalization drive signals in IGBT series circuits. Background Technology

[0002] Insulated-gate bipolar transistors (IGBTs) are widely used in high-voltage, high-capacity electronic circuits such as high-voltage transformers and high-voltage pulse power supplies due to their advantages such as fast switching speed and large current capacity. However, due to the limitations of current IGBT device design characteristics, process technology, and manufacturing capabilities, the withstand voltage of a single IGBT is no longer sufficient to meet requirements. Therefore, connecting multiple IGBTs in series has become the most direct and effective method to solve this problem. The main challenge in connecting multiple IGBTs in series is the voltage equalization problem among the IGBT devices.

[0003] IGBT voltage equalization issues are mainly divided into dynamic voltage equalization and static voltage equalization. Static voltage equalization refers to the balance of voltage across each IGBT when the series-connected IGBTs are at rest. Dynamic voltage equalization refers to the dynamic balance across the IGBTs when they are in the instantaneous state of being turned on or off. The main factor affecting IGBT static voltage equalization is the equivalent resistance characteristic of the IGBT in the off state. Therefore, the currently effective solution is to connect a non-inductive voltage equalization resistor in parallel across the collector and emitter of the IGBT. There are currently two main solutions for dynamic voltage equalization: The first is to introduce a passive voltage buffer circuit around the IGBT, mainly RC circuits and RCD circuits, to absorb the overvoltage generated during IGBT operation and slow down the rapid changes in voltage across the IGBT, thereby reducing the dynamic voltage difference between devices. Generally, the first dynamic voltage equalization method is only used as an auxiliary measure and needs to be combined with other voltage equalization methods. The second is the active voltage equalization method, including voltage clamping method, quasi-active gate control method, and magnetic core synchronization method. The main idea of ​​its implementation is to ensure the consistency of the IGBT drive signal by adding a magnetic ring or other artificial methods, and to control the switching process of the IGBT, thereby reducing the inconsistency of the IGBT switching process and the resulting dynamic voltage imbalance caused by individual IGBT differences.

[0004] As can be seen from the above, the two existing dynamic voltage equalization methods for IGBT series circuits cannot achieve active voltage equalization, that is, the initiative of dynamic voltage equalization is poor. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of poor initiative in dynamic voltage equalization of IGBT series circuits in existing dynamic voltage equalization methods, and to propose a self-adjusting device and method for active voltage equalization drive signals in IGBT series circuits.

[0006] The present invention discloses a self-adjusting device for an active voltage equalization drive signal in an IGBT series circuit, the self-adjusting device comprising multiple IGBT self-adjusting units and a control system;

[0007] Each of the multiple IGBT self-adjustment units corresponds one-to-one with each IGBT in the IGBT series circuit; each IGBT self-adjustment unit includes a drive signal generator, a drive circuit, an RCD buffer circuit, and a sampling circuit.

[0008] The drive signal generator is used to generate the initial drive signal and also to generate the final drive signal by advancing or delaying the generation time of the initial drive signal according to the adjustment signal output by the control system.

[0009] The driving circuit is used to amplify the initial driving signal generated by the driving signal generator and the final driving signal generated by the driving signal generator, and then applies the amplified initial driving signal and final driving signal to the gate of the IGBT respectively.

[0010] The RCD buffer circuit is used to change the resistance value of the resistor connected in parallel between the collector and emitter of the IGBT according to the adjustment signal output by the control system, thereby changing the terminal voltage between the collector and emitter of the IGBT.

[0011] The sampling circuit is used to collect the on / off timing and terminal voltage at the collector and emitter of the IGBT, and feeds back the on / off timing and terminal voltage to the control system in the form of sampling signals;

[0012] The control system receives sampling signals from multiple IGBT self-adjusting units and compares these signals. If the comparison results are different, the control system outputs an adjustment signal, which is then output to the drive signal generators and RCD buffer circuits of the multiple IGBT self-adjusting units. If the comparison results are the same, the control system outputs a working signal, which controls the multiple IGBTs connected in series to connect to the application circuit, enabling the application circuit to enter normal operating mode.

[0013] Furthermore, the self-regulating device also includes an auxiliary regulating power supply;

[0014] The auxiliary regulating power supply is used to provide auxiliary power to multiple IGBTs connected in series, and after receiving the working signal output from the control system, the auxiliary regulating power supply cuts off the auxiliary power supply to the multiple IGBTs connected in series.

[0015] Furthermore, the adjustment signals output by the control system include timing adjustment signals and voltage equalization signals;

[0016] The timing adjustment signal acts on the drive signal generator to advance or delay the generation time of the initial drive signal output by the drive signal generator, so that the drive signal generators in multiple IGBT self-adjustment units output the initial drive signal synchronously.

[0017] The equalizing signal acts on the RCD buffer circuit to change the resistance value of the resistor connected in parallel between the collector and emitter of the IGBT, so that the terminal voltage between the collector and emitter of multiple IGBTs is the same.

[0018] Furthermore, the RCD buffer circuit includes diode D1, diode D2, sliding rheostat R1, and capacitor C1;

[0019] The cathode of diode D1 is connected to a fixed terminal of sliding rheostat R1 and the anode of diode D2, and the cathode of diode D1 is connected to the collector of IGBT as an adjustment terminal of RCD buffer circuit.

[0020] The anode of diode D1 is connected to one end of capacitor C1, and the anode of diode D1 is connected to the emitter of IGBT as another adjustment terminal of RCD buffer circuit.

[0021] The other end of the capacitor C1 is connected to the moving slider of the variable resistor R1 and the cathode of the diode D2.

[0022] The equalizing signal is applied to the sliding rheostat R1 to change the position of the sliding slider of the rheostat R1.

[0023] A self-adjustment method for a self-adjusting device of an active voltage equalization drive signal in an IGBT series circuit, the self-adjustment method comprising the following steps:

[0024] Step 1: The sampling circuits of multiple IGBT self-adjusting units acquire sampling signals respectively; the sampling signals include on / off timing signals and terminal voltage signals;

[0025] Step 2: The control system determines whether the on / off timing signal and the terminal voltage signal in the sampled signal obtained in Step 1 are the same. If the on / off timing signals are different, the control system outputs a timing adjustment signal and executes Step 3. If the terminal voltage signals are different, the control system outputs a voltage equalization signal and executes Step 4. Otherwise, the control system outputs a working signal and executes Step 5.

[0026] Step 3: The timing adjustment signal is applied to the drive signal generator, and then the process returns to step 1.

[0027] Step 4: The equalizing signal is applied to the RCD buffer circuit, and the process returns to step 1.

[0028] Step 5: The working signals are applied to the auxiliary power supply and the application circuit respectively;

[0029] When the working signal is applied to the auxiliary regulating power supply, it controls the auxiliary regulating power supply to enter the off state; when the working signal is applied to the application circuit, it controls the multiple IGBTs connected in series to connect to the application circuit, so that the application circuit enters the normal working state.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] This invention starts with the voltage equalization result of IGBTs. It uses a sampling circuit to sample the IGBTs in real time and a control system to compare the sampling signals from different sampling circuits. Based on the comparison results, it adjusts the switching timing of the IGBTs and the terminal voltage between the collector and emitter, thereby ensuring the consistency of IGBT switching and achieving active voltage equalization. Therefore, the self-adjusting device has good proactive dynamic voltage equalization, ultimately achieving the goal of consistent IGBT voltage equalization, with a clear objective and higher working efficiency. Simultaneously, the active voltage equalization adjustment method of the self-adjusting device for the IGBT series circuit is independent of the IGBT device's own parameters, reducing the influence of these parameters. Furthermore, the active voltage equalization adjustment method of the self-adjusting device for the IGBT series circuit is independent of the IGBT switching process, reducing the impact of differences in IGBT switching processes caused by individual IGBT variations. Attached Figure Description

[0032] Figure 1 This is a block diagram illustrating the structural principle of a self-adjusting device for an active voltage equalization drive signal in an IGBT series circuit, as described in Specific Embodiment 1.

[0033] Figure 2 The circuit diagram of the RCD buffer circuit in the fourth specific implementation method is shown below.

[0034] Figure 3This is a flowchart of the self-adjustment method of the self-adjustment device for the active voltage equalization drive signal in an IGBT series circuit, as described in Specific Embodiment 5. Detailed Implementation

[0035] Specific Implementation Method 1: Combination Figure 1 This embodiment describes a self-adjusting device for an active voltage equalization drive signal in an IGBT series circuit. The self-adjusting device includes multiple IGBT self-adjusting units 1 and a control system 2.

[0036] Each IGBT self-adjustment unit 1 in the plurality of IGBT self-adjustment units 1 corresponds one-to-one with each IGBT 4 in the IGBT series circuit; each IGBT self-adjustment unit 1 includes a drive signal generator 5, a drive circuit 6, an RCD buffer circuit 7, and a sampling circuit 8.

[0037] The drive signal generator 5 is used to generate the initial drive signal and also to generate the final drive signal by advancing or delaying the generation time of the initial drive signal according to the adjustment signal output by the control system 2.

[0038] The drive circuit 6 is used to amplify the initial drive signal generated by the drive signal generator 5, and also to amplify the final drive signal generated by the drive signal generator 5, and apply the amplified initial drive signal and final drive signal to the gate of IGBT4 respectively.

[0039] RCD buffer circuit 7 is used to change the resistance value of the resistor connected in parallel between the collector and emitter of IGBT4 according to the adjustment signal output by the control system 2, thereby changing the terminal voltage between the collector and emitter of IGBT4.

[0040] The sampling circuit 8 is used to collect the on / off timing and terminal voltage of the collector and emitter of the IGBT4, and feeds back the on / off timing and terminal voltage to the control system 2 in the form of sampling signals;

[0041] The control system 2 is used to receive the sampling signals output by multiple IGBT self-adjustment units 1 and compare the sampling signals output by multiple IGBT self-adjustment units 1. If the comparison results are different, the control system 2 outputs an adjustment signal, which is output to the drive signal generator 5 and the RCD buffer circuit 7 of multiple IGBT self-adjustment units 1 respectively. If the comparison results are the same, the control system 2 outputs a working signal, which controls the multiple IGBTs 4 connected in series to connect with the application circuit 3, so that the application circuit 3 enters the normal working state.

[0042] In this embodiment, each IGBT self-adjustment unit 1 includes a drive signal generator 5; there is no connection between different drive signal generators 5; the control system 2 is the center of the active voltage equalization scheme algorithm, receives the sampling signal of each IGBT self-adjustment unit 1, performs timing adjustment on the drive signal generator 5, and adjusts the RCD buffer circuit 7 to achieve the same terminal voltage between the collector and emitter of different IGBTs 4; when the comparison results are the same, the control system 2 stops outputting the adjustment signal; and when the control system 2 compares different sampling signals 10 times and still cannot achieve the same comparison results, the control system 2 will output a protection signal, which directly acts on the gate of the IGBT 4, putting the IGBT 4 in the off state to prevent damage to the IGBT 4; the circuit protection process is that the control system 2 directly gives the IGBT 4 a protection signal, bypassing the drive signal generator 5 and the drive circuit 6, achieving a direct, efficient, and delay-free effect; and since the protection signal output is at the nanosecond level, it will not cause damage to the IGBT 4, protecting the circuit and related devices. Meanwhile, the comparison results are considered to be the same if they are within the preset allowable range, where the sampling signal time is within the nanosecond level.

[0043] Specific Implementation Method 2: This implementation method further defines the self-adjusting device for the active voltage equalization drive signal in an IGBT series circuit as described in Specific Implementation Method 1. In this implementation method, the self-adjusting device also includes an auxiliary regulating power supply 9.

[0044] The auxiliary regulating power supply 9 is used to provide auxiliary power to the multiple IGBTs 4 connected in series, and after receiving the working signal output from the control system 2, the auxiliary regulating power supply 9 cuts off the auxiliary power supply to the multiple IGBTs 4 connected in series.

[0045] In this embodiment, the auxiliary regulating power supply 9 is set up to apply an auxiliary voltage to the IGBT series circuit before the application circuit 3 starts working, so as to adjust the synchronization of the IGBT switching process; the output voltage of the auxiliary regulating power supply 9 is the highest withstand voltage of a single IGBT, so as to ensure that no IGBT4 is damaged if the voltage equalization of IGBT4 fails.

[0046] Specific Implementation Method 3: This implementation method further defines the self-adjusting device for the active voltage equalization drive signal in an IGBT series circuit as described in Specific Implementation Method 2. In this implementation method, the adjustment signal output by the control system 2 includes a timing adjustment signal and a voltage equalization signal.

[0047] The timing adjustment signal acts on the drive signal generator 5 to advance or delay the generation time of the initial drive signal output by the drive signal generator 5, so that the drive signal generators 5 in the multiple IGBT self-adjustment units 1 output the initial drive signal synchronously.

[0048] The voltage equalization signal acts on the RCD buffer circuit 7 to change the resistance value of the resistor connected in parallel between the collector and emitter of the IGBT4, so that the terminal voltage between the collector and emitter of multiple IGBT4s is the same.

[0049] In this embodiment, the timing adjustment signal is used by the control system 2 to adjust the drive signal generator 5. The timing adjustment signal controls the drive signal generator 5 to advance or delay the drive signal generated, thereby adjusting the IGBT on or off time.

[0050] Meanwhile, the RCD buffer circuit 7 is connected in parallel with the collector and emitter of the IGBT4. By changing the resistance of the RCD buffer circuit 7 connected to the circuit, the terminal voltage between the collector and emitter of the IGBT4 can be changed, ultimately making the terminal voltage between the collector and emitter of multiple IGBT4 the same.

[0051] Detailed Implementation Method Four: Combination Figure 2 This embodiment further defines the self-adjusting device for the active voltage equalization drive signal in an IGBT series circuit as described in Specific Embodiment 1. In this embodiment, the RCD buffer circuit 7 includes diode D1, diode D2, sliding rheostat R1, and capacitor C1.

[0052] The cathode of diode D1 is connected to a fixed terminal of sliding rheostat R1 and the anode of diode D2, and the cathode of diode D1 is connected to the collector of IGBT4 as an adjustment terminal of RCD buffer circuit 7.

[0053] The anode of diode D1 is connected to one end of capacitor C1, and the anode of diode D1 is connected to the emitter of IGBT4 as another adjustment terminal of RCD buffer circuit 7.

[0054] The other end of the capacitor C1 is connected to the moving slider of the variable resistor R1 and the cathode of the diode D2.

[0055] The equalizing signal is applied to the sliding rheostat R1 to change the position of the sliding slider of the rheostat R1.

[0056] In this embodiment, the position of the sliding slider of the sliding rheostat R1 is changed by using the equalizing signal, thereby changing the resistance value of the resistor connected to the RCD buffer circuit 7. Since the resistance value of the resistor connected to the RCD buffer circuit 7 changes, the terminal voltage between the collector and emitter of the IGBT4 connected in parallel with the RCD buffer circuit 7 changes accordingly, thus realizing the change of the terminal voltage between the collector and emitter of the IGBT4.

[0057] Specific Implementation Method Five: Combination Figure 3This embodiment describes a self-adjustment method for an active voltage equalization drive signal self-adjustment device in an IGBT series circuit. The self-adjustment method includes the following steps:

[0058] Step 1: The sampling circuits 8 of the multiple IGBT self-adjustment units 1 respectively acquire sampling signals; the sampling signals include on / off timing signals and terminal voltage signals;

[0059] Step 2: Control system 2 determines whether the on / off timing signal and the terminal voltage signal in the sampled signal obtained in step 1 are the same; if the on / off timing signals are different, control system 2 outputs a timing adjustment signal and executes step 3; if the terminal voltage signals are different, control system 2 outputs a voltage equalization signal and executes step 4; otherwise, control system 2 outputs a working signal and executes step 5.

[0060] Step 3: The timing adjustment signal is applied to the drive signal generator 5, and then the process returns to step 1.

[0061] Step 4: The equalizing signal is applied to RCD buffer circuit 7, and the process returns to step 1.

[0062] Step 5: The working signals are applied to the auxiliary regulating power supply 9 and the application circuit 3 respectively;

[0063] When the working signal is applied to the auxiliary regulating power supply 9, it controls the auxiliary regulating power supply 9 to enter the off state; when the working signal is applied to the application circuit 3, it controls the multiple IGBTs 4 connected in series to be connected to the application circuit 3, so that the application circuit 3 enters the normal working state.

[0064] In this embodiment, the auxiliary regulating power supply 9 is first turned on, and the drive signal generator 5, drive circuit 6, RCD buffer circuit 7 and sampling circuit 8 of multiple IGBT self-adjustment units 1 start working simultaneously. At this time, the auxiliary regulating power supply 9 applies an auxiliary voltage to the IGBT series circuit to ensure that no IGBT4 is damaged if the voltage equalization of IGBT4 fails. Then the sampling circuit 8 of multiple IGBT self-adjustment units 1 starts to acquire sampling signals respectively.

[0065] The self-adjustment method described herein is a reverse adjustment process that starts from the final voltage equalization result. Compared with the original method of taking measures to address voltage imbalance, the self-adjustment method described in this embodiment adopts a proactive approach, adjusting the drive signal in reverse to address the inconsistency between the sampled signal and the voltage equalization result, ultimately achieving the consistency of voltage equalization of the IGBT4. The objective is clear and the working efficiency is higher.

[0066] The addition of application circuit 3 is only to make it easier to describe the circuit engineering method. The self-adjustment method mentioned in this embodiment can be applied to any circuit design that requires IGBT series connection, and is not affected by the structure and parameters of application circuit 3 itself.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A self-adjusting device for an active voltage-equalizing drive signal in an IGBT series circuit, characterized in that, The self-adjusting device includes multiple IGBT self-adjusting units (1) and a control system (2); Each IGBT self-adjustment unit (1) in the plurality of IGBT self-adjustment units (1) corresponds one-to-one with each IGBT (4) in the IGBT series circuit; each IGBT self-adjustment unit (1) includes a drive signal generator (5), a drive circuit (6), an RCD buffer circuit (7) and a sampling circuit (8); The drive signal generator (5) is used to generate the initial drive signal and also to generate the final drive signal by advancing or delaying the generation time of the initial drive signal according to the adjustment signal output by the control system (2). The driving circuit (6) is used to amplify the initial driving signal generated by the driving signal generator (5) and to amplify the final driving signal generated by the driving signal generator (5), and to apply the amplified initial driving signal and final driving signal to the gate of the IGBT (4) respectively. The RCD buffer circuit (7) is used to change the resistance value of the resistor connected in parallel between the collector and emitter of the IGBT (4) according to the adjustment signal output by the control system (2), thereby changing the terminal voltage between the collector and emitter of the IGBT (4). The sampling circuit (8) is used to collect the on / off timing and terminal voltage of the collector and emitter of the IGBT (4), and feeds back the on / off timing and terminal voltage to the control system (2) in the form of sampling signals. The control system (2) is used to receive the sampling signals output by multiple IGBT self-adjustment units (1) and compare the sampling signals output by multiple IGBT self-adjustment units (1). If the comparison results are different, the control system (2) outputs an adjustment signal, which is output to the drive signal generator (5) and RCD buffer circuit (7) of multiple IGBT self-adjustment units (1) respectively. If the comparison results are the same, the control system (2) outputs a working signal, which controls the multiple IGBTs (4) connected in series to connect with the application circuit (3), so that the application circuit (3) enters the normal working state.

2. The self-adjusting device for active voltage equalization drive signal in an IGBT series circuit according to claim 1, characterized in that, The self-regulating device also includes an auxiliary regulating power supply (9); The auxiliary regulating power supply (9) is used to provide auxiliary power to the multiple IGBTs (4) connected in series. After the auxiliary regulating power supply (9) receives the working signal output from the control system (2), it cuts off the auxiliary power supply to the multiple IGBTs (4) connected in series.

3. The self-adjusting device for active voltage equalization drive signal in an IGBT series circuit according to claim 2, characterized in that, The control system (2) outputs a timing adjustment signal and a voltage equalization signal. The timing adjustment signal acts on the drive signal generator (5) to advance or delay the generation time of the initial drive signal output by the drive signal generator (5), so that the drive signal generator (5) in the multiple IGBT self-adjustment units (1) outputs the initial drive signal synchronously. The equalizing signal acts on the RCD buffer circuit (7) to change the resistance value of the resistor connected in parallel between the collector and emitter of the IGBT (4), so that the terminal voltage between the collector and emitter of multiple IGBTs (4) is the same.

4. The self-adjusting device for active voltage equalization drive signal in an IGBT series circuit according to claim 3, characterized in that, The RCD buffer circuit (7) includes diode D1, diode D2, sliding rheostat R1 and capacitor C1; The cathode of diode D1 is connected to a fixed terminal of sliding rheostat R1 and the anode of diode D2, and the cathode of diode D1 is connected to the collector of IGBT (4) as an adjustment terminal of RCD buffer circuit (7). The anode of the diode D1 is connected to one end of the capacitor C1, and the anode of the diode D1 is connected to the emitter of the IGBT (4) as the other adjustment terminal of the RCD buffer circuit (7). The other end of the capacitor C1 is connected to the moving slider of the variable resistor R1 and the cathode of the diode D2. The equalizing signal is applied to the sliding rheostat R1 to change the position of the sliding slider of the rheostat R1.

5. The self-adjustment method of the self-adjustment device for the active voltage equalization drive signal in an IGBT series circuit as described in claim 3, characterized in that, The self-regulation method includes the following steps: Step 1: The sampling circuits (8) of multiple IGBT self-adjustment units (1) acquire sampling signals respectively; the sampling signals include on / off timing signals and terminal voltage signals; Step 2: The control system (2) determines whether the on / off timing signal and the terminal voltage signal in the sampled signal obtained in Step 1 are the same; if the on / off timing signals are different, the control system (2) outputs a timing adjustment signal and executes Step 3; if the terminal voltage signals are different, the control system (2) outputs a voltage equalization signal and executes Step 4; otherwise, the control system (2) outputs a working signal and executes Step 5. Step 3: The timing adjustment signal is applied to the drive signal generator (5), and then the process returns to step 1. Step 4: The equalizing signal is applied to the RCD buffer circuit (7), and then the process returns to step 1. Step 5: The working signals are applied to the auxiliary regulating power supply (9) and the application circuit (3) respectively; When the working signal is applied to the auxiliary regulating power supply (9), it controls the auxiliary regulating power supply (9) to enter the off state; when the working signal is applied to the application circuit (3), the working signal controls the multiple IGBTs (4) connected in series to connect with the application circuit (3), so that the application circuit (3) enters the normal working state.

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