Optimization control method and system for reducing turn-off overvoltage of high-power device

Abstract

The invention provides an optimal control method and system for reducing turn-off overvoltage of a high-power device. The method comprises the following steps: acquiring a working state of an IGBT (Insulated Gate Bipolar Translator) device, a loop current change rate of a bridge arm of a half-bridge power module and a current change rate reference value; judging whether the working state of the IGBT device is a turn-off state or not, if not, updating the change rate reference value based on turn-off overvoltage data and a voltage preset value in a preset time period, and if yes, controlling a gate switch of the IGBT device based on the change rate reference value and the loop current change rate; according to the invention, based on the updated change rate reference value and the loop current change rate, the gate pole switch of the IGBT device is controlled, the change frequency of the gate pole switch is reduced while the turn-off overvoltage is suppressed, and optimal control in the turn-off process of the high-power device IGBT is realized.

Description

Technical Field

[0001] The present invention belongs to the field of power electronic systems, and specifically relates to an optimization control method and system for reducing shutdown overvoltage of high-power devices. Background Art

[0002] Power electronic equipment technology is the technical core of building a new power system. High-power turn-off devices are key components of power electronic equipment. At present, the most widely used high-power turn-off devices are insulated gate bipolar transistors (IGBTs), which can be regarded as switching devices integrated by metal oxide semiconductor field effect transistors (MOSFETs) and bipolar junction transistors (BJTs). They have the advantages of high current, high voltage resistance and low on-state voltage drop. In recent years, they have been widely valued in various industries at home and abroad, and have high application value in the offshore wind power field of power systems.

[0003] When the IGBT device is turned off, it will generate a turn-off overvoltage. If the overvoltage is large and close to the device limit, it will affect the device life. At present, the existing gate modulation strategy is to make the IGBT device in the off state under high-frequency changing positive and negative voltages, thereby reducing the device's turn-off overvoltage, but it is easy to cause damage to the device and reduce the device's working life. How to further optimize this problem and apply it to typical scenarios has very important research significance and application value. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes an optimization control method for reducing the shutdown overvoltage of a high-power device, comprising:

[0005] Obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value;

[0006] Determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the off overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

[0007] Preferably, updating the change rate reference value based on the shutdown overvoltage data and the voltage preset value within a preset period of time includes:

[0008] Determine whether the shutdown overvoltage data within a preset time period is greater than a preset voltage value, and if so, reduce the change rate reference value based on a preset step size, otherwise, increase the change rate reference value based on a preset step size;

[0009] The voltage preset value is determined based on historical overvoltage values ​​and dead time.

[0010] Preferably, the controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate includes:

[0011] It is determined whether the loop current change rate is greater than a current change rate reference value. If so, the gate switch on the gate branch of the IGBT device is turned off; otherwise, the gate switch on the gate branch of the IGBT device is turned on.

[0012] Preferably, after determining whether the working state of the IGBT device is the off state and before controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, the method further includes:

[0013] The gate resistor connected in series with the gate switch is switched from a first gate resistor to a second gate resistor, wherein the resistance of the second gate resistor is greater than the resistance of the first gate resistor.

[0014] Preferably, the turn-off overvoltage data within the preset time period is the turn-off overvoltage value when the IGBT device was in the turn-off state last time.

[0015] Based on the same inventive concept, the present invention application also proposes an optimized control system for reducing the shutdown overvoltage of a high-power device, comprising:

[0016] Data acquisition module: used to obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value;

[0017] Control module: used to determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the shutdown overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

[0018] Preferably, the control module updates the change rate reference value based on the shutdown overvoltage data and the voltage preset value within a preset period of time, including:

[0019] Determine whether the shutdown overvoltage data within a preset time period is greater than a preset voltage value, and if so, reduce the change rate reference value based on a preset step size, otherwise, increase the change rate reference value based on a preset step size;

[0020] The voltage preset value is determined based on historical overvoltage values ​​and dead time.

[0021] Preferably, the control module controls the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, including:

[0022] It is determined whether the loop current change rate is greater than a current change rate reference value. If so, the gate switch on the gate branch of the IGBT device is turned off; otherwise, the gate switch on the gate branch of the IGBT device is turned on.

[0023] Preferably, after determining whether the working state of the IGBT device is the off state and before controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, the control module further includes:

[0024] The gate resistor connected in series with the gate switch is switched from a first gate resistor to a second gate resistor, wherein the resistance of the second gate resistor is greater than the resistance of the first gate resistor.

[0025] Preferably, the turn-off overvoltage data within a preset time period in the data acquisition module is the turn-off overvoltage value when the IGBT device was in the turn-off state last time.

[0026] Compared with the closest prior art, the present invention has the following beneficial effects:

[0027] The present invention application provides an optimized control method and system for reducing the shutdown overvoltage of a high-power device, including: obtaining the working state of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value; judging whether the working state of the IGBT device is the shutdown state, if not, updating the change rate reference value based on the shutdown overvoltage data and the voltage preset value within a preset time period, and if so, controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate; the present invention application controls the gate switch of the IGBT device based on the updated change rate reference value and the loop current change rate, reduces the change frequency of the gate switch while suppressing the shutdown overvoltage, and realizes optimized control of the high-power device IGBT during the shutdown process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic flow chart of an optimization control method for reducing the shutdown overvoltage of a high-power device provided by the present invention;

[0029] Figure 2 It is a typical half-bridge power module topology diagram;

[0030] Figure 3 The principle topology of a gate overvoltage optimization control method provided by the present invention;

[0031] Figure 4 A flowchart of an optimization control method applied to a typical half-bridge power module provided by the present invention;

[0032] Figure 5A schematic diagram showing the gate voltage comparison before and after use of an optimization control method provided by the present invention;

[0033] Figure 6 A structural diagram of an optimized control system for reducing shutdown overvoltage of high-power devices provided in the present application. DETAILED DESCRIPTION

[0034] The specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings.

[0035] Embodiment 1:

[0036] The present invention provides an optimization control method for reducing the shutdown overvoltage of a high-power device. Specifically, Figure 1 As shown, it is a flow chart of an optimization control method provided by the present invention, comprising the following steps:

[0037] Step 1: Obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value;

[0038] Step 2: Determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the shutdown overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

[0039] At present, the typical half-bridge power module topology is as follows Figure 2 As shown, due to the presence of stray inductance, the IGBT device will cause a large current change rate during shutdown, which will in turn generate a large overvoltage. The gate modulation strategy of the prior art causes the gate voltage to fluctuate between high and low levels at a high frequency during the control process, and the gate of the IGBT device is subject to high-frequency positive and negative voltage changes, which will affect the service life of the IGBT device. The present invention applies to reduce the gate shutdown frequency of the IGBT in the off state based on the loop current change rate, thereby suppressing the shutdown overvoltage and reducing the change frequency of the gate switch, thereby reducing the probability of device damage and optimizing the technical effect of the prior art control method. Figure 3 As shown, it is a principle circuit topology diagram of an optimization control method provided by the present invention. In the figure, Q1 is a gate-off loop switch, Q2 is a gate-on loop switch, and both Q1 and Q2 are controlled by a driving control circuit. on is the first gate resistor, R onh is the second gate resistance, di / dt is the loop current change rate of the bridge arm of the half-bridge power module, and the present invention uses it as a feedback signal to control the on-off of the gate switch, thereby slowing down the current rise and fall speed, thereby achieving the effect of reducing overvoltage.

[0040] Specifically, in step 1, the change rate reference value is updated based on the shutdown overvoltage data and the voltage preset value within a preset time period when the IGBT device is in a non-shutdown state. The preset time period can be any time period specified as needed. In the embodiment of the present disclosure, it is the shutdown overvoltage value when the IGBT device was last shut down. The change rate reference value is a value used to determine whether the value of the loop current change rate of the bridge arm of the half-bridge power module meets the requirements. During initialization, the change rate reference value is an initial value given based on historical experimental data, and is then updated based on the shutdown overvoltage data and the voltage preset value within a preset time period.

[0041] Step 2 is as follows: Figure 4 As shown, the flowchart of the optimization control method proposed in the present invention application when applied to a typical half-bridge power module. First, the state of the IBGT device is determined. If the state of the IGBT device is a non-turn-off state, the above-mentioned change rate reference value is updated according to the turn-off overvoltage value of the last IGBT device in the circuit and the voltage preset value. Among them, the voltage preset value is determined based on the historical turn-off overvoltage value level of the device and the dead time of the device, which is used to determine whether the value of the turn-off overvoltage data within the preset time period meets the requirements. In the embodiment of the present disclosure, the voltage preset value is a judgment value k. When the turn-off overvoltage value (U) of the last IGBT device is greater than the judgment value k, the change rate reference value (di0 / dt) is reduced according to the preset step size, otherwise the change rate reference value (di0 / dt) is increased according to the preset step size. The present invention application based on the dynamically updated change rate reference value can make the adjustment strategy more in line with the actual state of the circuit and achieve more scientific and accurate optimization control.

[0042] If the IGBT is in the off state, then based on the selected change rate reference value (di0 / dt), it is determined whether the loop current change rate (di / dt) of the bridge arm of the half-bridge power module is greater than the current change rate reference value. If so, a shutdown signal is fed back to the drive control circuit, and the control is switched to the shutdown loop switch (Q1) to turn off the gate; otherwise, an on signal is fed back to the drive control circuit, and the control is switched to the on loop switch (Q2) to turn on the gate. It should be noted that the on loop switch is connected to the first gate resistor and the second gate resistor, and the second gate resistor is a large resistance resistor proposed in the present invention.

[0043] The present invention protects the device by using a second gate resistor greater than a preset value of the resistor as the input resistor of the gate. It should be noted that, according to different devices and different effects achieved, the setting range of the preset value is also different. In the embodiment of the present disclosure, its range is several times the original gate resistance value. The determination of its value can be determined by referring to the recommended value of the device manual, or by experimental testing, after comprehensively comparing factors such as the turn-off overvoltage and the turn-off time, to determine the optimal value of the gate resistance value. The introduction of a resistor greater than the preset value is mainly used to slow down the gate voltage change rate caused by the high and low levels of the high frequency injection of the driving circuit, so as to protect the gate of the IGBT device. In the embodiment of the present disclosure, the original input gate resistor is the first gate resistor. During the device shutdown process, when the optimization control method proposed in the present invention is adopted, the conduction loop switch (Q2) is driven to connect the second gate resistor; when the optimization control method proposed in the present invention is not adopted, the conduction loop switch (Q2) is driven to connect the first gate resistor. The present invention application reduces the gate voltage change rate caused by the high-frequency injection of high and low levels of the driving circuit through the optimization strategy of switching the large-resistance gate input resistor, thereby reducing the probability of IGBT device failure, protecting the device, and improving the device life of the IGBT. On the whole, the optimization control method proposed in the present invention application also better realizes its function of suppressing overvoltage, and further optimizes the control method for suppressing overvoltage when high-power devices are turned off.

[0044] In addition, different current change rate reference values ​​will have different effects on the overvoltage suppression effect. Three different current change rate reference values ​​of 2kA / us, 1kA / us and 0.5kA / us are selected to illustrate the different effects caused by different values. Simulation is performed based on a pre-built typical half-bridge power module model, using the ratio of the overvoltage value after the application of the present invention to the actual overvoltage as an indicator. The comparison results are shown in Table 1.

[0045] Table 1

[0046] Modulation conditions index 2kA / us 1.232 1kA / us 1.109 0.5kA / us 1.055

[0047] From Table 1, we can see that when applying the gate modulation strategy, the smaller the current change rate reference value is set, the better the overvoltage suppression effect is. However, too small a current change rate reference value will also lead to too long a shutdown delay, which to a certain extent will bring the risk of a direct short circuit between the upper and lower tubes due to missing the dead time. Therefore, the modulation parameters should also be selected based on the dead time set in actual application.

[0048] The gate voltage schematic diagram of the optimization control method proposed in the present invention and the control method of the prior art is shown in FIG. Figure 5As shown, the waveform diagram in the upper part is the gate voltage change of the original strategy, and the waveform diagram in the lower part is the gate voltage change after optimization by an optimization control method for reducing the shutdown overvoltage of high-power devices proposed by the present invention. It can be seen that after a resistance greater than a preset value is used as the input resistance of the gate, the duration of the gate low level becomes longer and the switching frequency is reduced. The present invention proposes an optimization control method for reducing the shutdown overvoltage of high-power devices, which indeed achieves the technical effect of reducing the shutdown frequency during the shutdown process and plays a role in protecting IGBT devices. Based on the characteristics of IGBT devices, the present invention optimizes the current gate modulation strategy for reducing the shutdown overvoltage in the half-bridge power module, effectively reducing the shutdown overvoltage of the power device while reducing the failure rate of the IGBT device. When applied to related equipment of the power transmission system, the cost is reduced while the equipment life is increased. This invention can also be applied to the field of flexible direct current transmission.

[0049] Embodiment 2:

[0050] Based on the same inventive concept, the present invention also provides an optimized control system for reducing the shutdown overvoltage of high-power devices. The system structure is as follows: Figure 6 As shown, including:

[0051] Data acquisition module: used to obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value;

[0052] Control module: used to determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the shutdown overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

[0053] Preferably, the control module updates the change rate reference value based on the shutdown overvoltage data and the voltage preset value within a preset period of time, including:

[0054] Determine whether the shutdown overvoltage data within a preset time period is greater than a preset voltage value, and if so, reduce the change rate reference value based on a preset step size, otherwise, increase the change rate reference value based on a preset step size;

[0055] The voltage preset value is determined based on historical overvoltage values ​​and dead time.

[0056] Preferably, the control module controls the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, including:

[0057] It is determined whether the loop current change rate is greater than a current change rate reference value. If so, the gate switch on the gate branch of the IGBT device is turned off; otherwise, the gate switch on the gate branch of the IGBT device is turned on.

[0058] Preferably, after determining whether the working state of the IGBT device is the off state and before controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, the control module further includes:

[0059] The gate resistor connected in series with the gate switch is switched from a first gate resistor to a second gate resistor, wherein the resistance of the second gate resistor is greater than the resistance of the first gate resistor.

[0060] Preferably, the turn-off overvoltage data within a preset time period in the data acquisition module is the turn-off overvoltage value when the IGBT device was in the turn-off state last time.

[0061] The present invention application controls the gate switch of the IGBT device by using the updated change rate reference value and the loop current change rate as control feedback signals in the control module, thereby reducing the change frequency of the gate switch while suppressing the shutdown overvoltage, thereby achieving optimized control of the IGBT shutdown process of the high-power device and providing an optimized control system for reducing the shutdown overvoltage of the high-power device.

[0062] Those skilled in the art will appreciate that the embodiments of the present invention application can be provided as methods, systems, or computer program products. Therefore, the present invention application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present invention application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0063] The present invention application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present invention application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0064] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0065] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention application rather than to limit its protection scope. Although the present invention application is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention application, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. An optimization control method for reducing the shutdown overvoltage of a high-power device, characterized in that: include: Obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value; Determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the off overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

2. The method according to claim 1, characterized in that The updating of the change rate reference value based on the shutdown overvoltage data and the voltage preset value within the preset time period includes: Determine whether the shutdown overvoltage data within a preset time period is greater than a preset voltage value, and if so, reduce the change rate reference value based on a preset step size, otherwise, increase the change rate reference value based on a preset step size; The voltage preset value is determined based on historical overvoltage values ​​and dead time.

3. The method according to claim 2, characterized in that The controlling of the gate switch of the IGBT device based on the change rate reference value and the loop current change rate includes: It is determined whether the loop current change rate is greater than a current change rate reference value. If so, the gate switch on the gate branch of the IGBT device is turned off; otherwise, the gate switch on the gate branch of the IGBT device is turned on.

4. The method according to claim 1, characterized in that: After determining whether the working state of the IGBT device is the off state and before controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, the method further includes: The gate resistor connected in series with the gate switch is switched from a first gate resistor to a second gate resistor, wherein the resistance of the second gate resistor is greater than the resistance of the first gate resistor.

5. The method according to claim 1, characterized in that The turn-off overvoltage data within the preset time period is the turn-off overvoltage value when the IGBT device was in the turn-off state last time.

6. An optimization control system for reducing the shutdown overvoltage of high-power devices, characterized in that: include: Data acquisition module: used to obtain the working status of the IGBT device, the loop current change rate of the bridge arm of the half-bridge power module and the current change rate reference value; Control module: used to determine whether the working state of the IGBT device is the off state. If not, update the change rate reference value based on the shutdown overvoltage data and the voltage preset value within the preset time period. If so, control the gate switch of the IGBT device based on the change rate reference value and the loop current change rate.

7. The system according to claim 6, characterized in that The control module updates the change rate reference value based on the shutdown overvoltage data and the voltage preset value within a preset period of time, including: Determine whether the shutdown overvoltage data within a preset time period is greater than a preset voltage value, and if so, reduce the change rate reference value based on a preset step size, otherwise, increase the change rate reference value based on a preset step size; The voltage preset value is determined based on historical overvoltage values ​​and dead time.

8. The system according to claim 7, characterized in that The control module controls the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, including: It is determined whether the loop current change rate is greater than a current change rate reference value. If so, the gate switch on the gate branch of the IGBT device is turned off; otherwise, the gate switch on the gate branch of the IGBT device is turned on.

9. The system according to claim 6, characterized in that After determining whether the working state of the IGBT device is the off state and before controlling the gate switch of the IGBT device based on the change rate reference value and the loop current change rate, the control module further includes: The gate resistor connected in series with the gate switch is switched from a first gate resistor to a second gate resistor, wherein the resistance of the second gate resistor is greater than the resistance of the first gate resistor.

10. The system according to claim 6, characterized in that The turn-off overvoltage data within the preset time period in the data acquisition module is the turn-off overvoltage value when the IGBT device was in the turn-off state last time.

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