Drive circuit, system, and control method for power semiconductor

Abstract

The application provides a kind of driving circuit, system and control method of power semiconductor, it is related to electronic circuit technical field, including: positive power supply end provides positive driving voltage to the gate of power semiconductor device;First and second positive power supply module respectively output driving positive voltage, and the driving positive voltage that second positive power supply module outputs is higher;Switching module controls the on-off of second positive power supply module and positive power supply end;Negative power supply end provides off negative voltage;Control module controls switching module to keep open in the power semiconductor device opening transient process, controls switching module to close after power semiconductor device enters conduction steady state, controls switching module to restore open before the off transient process of power semiconductor device starts.This application realizes the accurate control of conduction loss by the cooperative control of double positive power supply module and switching module, reduces the conduction loss, improves system efficiency, enhances device operation reliability.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a driving circuit, system and control method for power semiconductors. Background Technology

[0002] In high-power power electronic converters such as solid-state transformers, high-voltage SVG, and high-voltage frequency converters, cascaded H-bridge topologies are commonly used. The core power switching devices have extremely high requirements for system efficiency, so the switching frequency is usually low, the power transistor conduction time is long, and the conduction loss accounts for a high proportion of the total loss. At present, in order to drive power semiconductor devices such as IGBTs to operate reliably, a drive circuit with positive and negative dual power supplies is usually used. The positive power supply provides a constant voltage of about +15V to turn on the power transistor, and the negative power supply provides a voltage of -5V to -15V for reliable turn-off and to prevent false triggering.

[0003] However, existing drive circuits have the following shortcomings in practical applications: First, the on-state voltage drop of power semiconductor devices is closely related to the gate drive voltage amplitude. The higher the drive voltage, the lower the on-state voltage drop and the smaller the conduction loss. However, in existing solutions, the gate drive voltage remains constant throughout the conduction period. Due to the influence of the internal impedance of the drive circuit and the line voltage drop, the actual voltage reaching the gate is often lower than the theoretical value, resulting in a higher on-state voltage drop and conduction loss, which limits further improvement in system efficiency. Second, if the entire positive power supply voltage is simply increased to reduce conduction loss, severe gate voltage spikes will be generated during the switching process due to the parasitic inductance of the line and the Miller capacitance effect, which may break down the gate oxide layer of the power device and bring reliability risks. In addition, existing drive circuits cannot dynamically adjust the drive voltage according to different operating stages of the power device, making it difficult to achieve optimal control of conduction loss while ensuring switching safety.

[0004] Therefore, a driving circuit capable of providing different amplitude driving voltages in different operating stages of power semiconductor switching devices urgently needs to be studied. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a driving circuit, system, and control method for power semiconductors, solving the technical problem in the prior art where it is difficult to balance conduction losses and switching safety due to the gate drive voltage remaining constant throughout the entire conduction period.

[0006] The first aspect of the present invention provides a driving circuit for a power semiconductor, comprising: The positive power supply terminal is used to provide a positive drive voltage to the gate of power semiconductor devices; The first positive power supply module has its output terminal connected to the positive power supply terminal and is used to output the first driving positive voltage; The second positive power supply module has its output terminal connected to the positive power supply terminal via a switching module, and is used to output a second driving positive voltage, wherein the second driving positive voltage is higher than the first driving positive voltage; The switching module is connected in series between the second positive power supply module and the positive power supply terminal, and is used to control the on / off state between the second positive power supply module and the positive power supply terminal. When the switching module is in the off state, the first driving positive voltage is output to the gate of the power semiconductor device. When the switching module is in the closed state, the second driving positive voltage is output to the gate of the power semiconductor device. The negative power supply terminal is used to provide a negative turn-off voltage to the gate of power semiconductor devices; The control module is connected to the signal control terminals of the switch module and the power semiconductor device, respectively. It is used to control the switch module to remain in the off state during the turn-on transient process of the power semiconductor device, control the switch module to switch to the closed state after the power semiconductor device enters the conduction steady state, and control the switch module to return to the off state before the turn-off transient process of the power semiconductor device begins.

[0007] A second aspect of the present invention provides a driving system for power semiconductors, comprising: The H-bridge inverter circuit includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first power transistor and a second power transistor connected in series, and the second bridge arm includes a third power transistor and a fourth power transistor connected in series. The gates of the first power transistor, the second power transistor, the third power transistor and the fourth power transistor are respectively connected to the driving circuit as described above. The load is connected between the first bridge arm and the second bridge arm; The coordination module is connected to the control modules of the four drive circuits respectively, and is used to provide synchronous control commands to the control modules.

[0008] A third aspect of the present invention provides a power semiconductor driving circuit control method, the method being applied to a power semiconductor driving circuit as described in any of the preceding claims, the method comprising: Obtain the conduction pulse width time corresponding to the activation command, and determine whether the conduction pulse width time is less than or equal to a preset minimum conduction time threshold. When the conduction pulse width time is less than or equal to the shortest conduction time threshold, the switching module is kept in the off state, and the first positive power supply module provides a first driving positive voltage to the gate of the power semiconductor device until it is turned off. When the conduction pulse width time is greater than the shortest conduction time threshold, after the power semiconductor device receives an externally input turn-on signal, the first positive power supply module is controlled to output a first driving positive voltage to the gate of the power semiconductor device. At a first preset moment after receiving the activation signal, the switch module is controlled to switch to the closed state, and the second positive power supply module is controlled to connect, so that the second positive power supply module outputs a second driving positive voltage to the gate of the power semiconductor device; At a second preset time after receiving the turn-on signal, or when receiving an externally input turn-off signal, the switch module is controlled to return to the off state, and the first positive power supply module outputs the first driving positive voltage to the gate of the power semiconductor device. The second preset time is earlier than the end time of the turn-on pulse width. After the second positive power module is disconnected, the power semiconductor device is controlled to turn off.

[0009] The power semiconductor driving circuit, system, and control method provided by this invention, after the power semiconductor device enters the conduction steady state, controls the switching module to switch to the closed state, so that the second positive power supply module with a higher voltage is connected to the positive power supply terminal to provide a positive driving voltage to the gate, effectively raising the gate potential in the steady state stage, thereby reducing the conduction voltage drop and conduction loss; at the same time, during the turn-on transient process, the control module is kept open, and only the first positive power supply module with a lower voltage is powered, avoiding the gate voltage spike induced by high voltage during the switching transient process from the source, eliminating the safety hazard of gate oxide layer breakdown; furthermore, this application also realizes the adjustment of the driving voltage according to the working stage. Before the turn-off transient process begins, the control module controls the switching module to return to the open state, and the second positive power supply module is disconnected in time, so that the driving voltage drops back to the lower voltage level of the first positive power supply module before turn-off, ensuring that the turn-off process is not prolonged due to excessive voltage, thereby realizing the dynamic adaptation of the driving voltage throughout the entire process of turn-on transient, conduction steady state, and turn-off transient. In summary, this application achieves precise control of conduction losses by coordinating the control of the dual positive power supply module and the switching module, ensuring reliable turn-on and turn-off of the power semiconductor, thereby reducing conduction losses, improving system efficiency, and enhancing device operational reliability.

[0010] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0011] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0012] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 A schematic diagram of the overall structure of the driving circuit for the power semiconductor in one embodiment of this application; Figure 2 A specific circuit structure diagram of the power semiconductor driving system provided in one embodiment of this application; Figure 3 A flowchart of a power semiconductor drive circuit control method in one embodiment provided in this application.

[0013] In the picture: Q1, first power transistor; Q2, second power transistor; Q3, third power transistor; Q4, fourth power transistor; Vcc, positive power supply terminal; Vcc1, first positive power supply module; Vcc2, second positive power supply module; Vee, negative power supply terminal; S2, switching circuit; Rs, slope control resistor; Ton_min, the shortest conduction time threshold; t1, the first preset time; t2, the second preset time. Detailed Implementation

[0014] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0015] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0016] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0017] The first aspect of this invention provides a driving circuit for power semiconductors, such as... Figure 1 As shown, it includes: a positive power supply terminal for providing a positive drive voltage to the gate of a power semiconductor device; a first positive power supply module, with its output terminal connected to the positive power supply terminal for outputting a first drive positive voltage; a second positive power supply module, with its output terminal connected to the positive power supply terminal via a switch module for outputting a second drive positive voltage, wherein the second drive positive voltage is higher than the first drive positive voltage; a switch module, connected in series between the second positive power supply module and the positive power supply terminal for controlling the on / off state between the second positive power supply module and the positive power supply terminal, wherein when the switch module is in the off state, the first drive positive voltage is output to the gate of the power semiconductor device, and when the switch module is in the closed state, the second drive positive voltage is output to the gate of the power semiconductor device; a negative power supply terminal for providing a turn-off negative voltage to the gate of the power semiconductor device; and a control module, connected to the signal control terminals of the switch module and the power semiconductor device respectively, for controlling the switch module to remain in the off state during the turn-on transient process of the power semiconductor device, controlling the switch module to switch to the closed state after the power semiconductor device enters the on-steady state, and controlling the switch module to return to the off state before the turn-off transient process of the power semiconductor device begins.

[0018] The power semiconductor driving circuit provided by this invention, after the power semiconductor device enters the conduction steady state, controls the switching module to switch to the closed state, so that the second positive power supply module with a higher voltage is connected to the positive power supply terminal to provide a positive driving voltage to the gate, effectively raising the gate potential in the steady state stage, thereby reducing the conduction voltage drop and conduction loss; at the same time, during the turn-on transient process, the control module is kept open, and only the first positive power supply module with a lower voltage is powered, avoiding the gate voltage spike induced by high voltage during the switching transient process from the source, eliminating the safety hazard of gate oxide layer breakdown; furthermore, this application also realizes the adjustment of driving voltage according to the working stage. Before the turn-off transient process begins, the control module controls the switching module to return to the open state, timely disconnecting the second positive power supply module, so that the driving voltage drops back to the lower voltage level of the first positive power supply module before turn-off, ensuring that the turn-off process is not prolonged due to excessive voltage, thereby realizing the dynamic adaptation of driving voltage throughout the entire process of turn-on transient, conduction steady state, and turn-off transient. In summary, this application achieves precise control of conduction losses by coordinating the control of the dual positive power supply module and the switching module, ensuring reliable turn-on and turn-off of the power semiconductor, thereby reducing conduction losses, improving system efficiency, and enhancing device operational reliability.

[0019] Specifically, in the above embodiments, the switching module includes a semiconductor switching device, the control terminal of the semiconductor switching device is connected to the output terminal of the control module, the first connection terminal of the semiconductor switching device is connected to the output terminal of the second positive power supply module, and the second connection terminal of the semiconductor switching device is connected to the positive power supply terminal.

[0020] In this embodiment, the switching module is implemented using a semiconductor switching device. The semiconductor switching device has three ports: a control terminal, a first connection terminal, and a second connection terminal. The control terminal is electrically connected to the output terminal of the control module and is used to receive the switch control signal issued by the control module. The switch control signal determines whether the semiconductor switching device is in an on or off state. The first connection terminal is electrically connected to the output terminal of the second positive power supply module, serving as a voltage input terminal. The second connection terminal is electrically connected to the positive power supply terminal, serving as a voltage output terminal. Therefore, the semiconductor switching device is connected in series between the second positive power supply module and the positive power supply terminal. When the control module outputs a closing command, the first and second connection terminals of the semiconductor switching device exhibit a low-resistance conducting state. In the first positive power supply module, the second driving positive voltage output by the second positive power supply module is transmitted to the positive power supply terminal via a semiconductor switching device. When the control module outputs a disconnect command, the first connection terminal and the second connection terminal are in a high-impedance isolation state, and the path between the second positive power supply module and the positive power supply terminal is cut off. This application uses semiconductor switching devices as the switching module, typically MOSFETs, IGBTs, or transistors, which have the advantages of fast response speed, low on-resistance, and easy integration and control. They can accurately respond to the timing commands of the control module, ensuring that the second positive power supply is connected immediately after the turn-on transient ends and reliably disconnected before the turn-off transient begins, thereby accurately realizing time-sharing power supply control and providing a reliable hardware foundation for reducing conduction losses and ensuring switch safety.

[0021] Furthermore, the control module includes: a drive signal receiving end for receiving externally input turn-on and turn-off signals; a timing unit for generating time reference signals corresponding to the turn-on transient process, conduction steady state, and turn-off transient process of the power semiconductor device; and an output end connected to the control end of the switching module for outputting corresponding switch control signals based on the turn-on or turn-off signals received by the drive signal receiving end and the time reference signals generated by the timing unit, wherein the switch control signals are used to control the on / off state of the switching module.

[0022] Specifically, the control module includes a drive signal receiver, a timing unit, and an output terminal. The drive signal receiver receives turn-on and turn-off signals from an external controller, serving as the interface between the control module and the external system, converting external commands into internally recognizable logic levels. The timing unit generates multiple time reference signals corresponding to the operating states of the power semiconductor device, generating different time references for the turn-on transient process, the conduction steady state, and the turn-off transient process. For example, the time reference corresponding to the turn-on transient process defines the duration from the issuance of the turn-on signal to the full conduction of the power device; the time reference corresponding to the conduction steady state defines the duration interval for the power device to maintain the conduction state; and the output terminal... The time base corresponding to the transient process is used to define the duration from the early shutdown of the second positive power supply to the issuance of the shutdown signal. The timing unit can be implemented using an RC delay circuit, a counter circuit, a monostable trigger circuit, or a digital timer. The output terminal is connected to the control terminal of the switching module. Based on the turn-on or turn-off signal received by the drive signal receiver and the time base signal generated by the timing unit, the corresponding switching control signal is output. Specifically, after receiving the turn-on signal, the output terminal outputs a disconnect command during the turn-on transient process. When the timing unit indicates that the turn-on transient process has ended, the output terminal switches to a close command. When the timing unit indicates that the turn-off transient process is about to begin, or when a turn-off signal is received, the output terminal resumes the disconnect command.

[0023] In this embodiment, by dividing the control module into three functional units—a drive signal receiving end, a timing unit, and an output end—precise timing control of the switching module is achieved. The existence of the timing unit enables the control module to generate a time reference that matches the switching characteristics of the power device autonomously, without relying on complex external timing logic. This ensures that the timing of the connection and disconnection of the second positive power supply is precise and controllable, thereby reducing conduction losses while ensuring switching safety.

[0024] In some embodiments, it can be further extended to multi-threshold segmented control. For example, multiple positive power supply modules with different amplitudes are set up. The control module connects to the higher voltage power supply module in stages according to the conduction time or working stage of the power device, so that the gate drive voltage rises in a stepwise manner, further optimizing the balance between conduction loss and switching safety. It is suitable for ultra-high power application scenarios with extremely high efficiency requirements.

[0025] Furthermore, the driving circuit also includes a first current sampling module, which is used to collect the bridge arm current of the power semiconductor device; the control module also includes a first comparison unit, which is connected to the first current sampling module and is used to compare the bridge arm current collected by the first current sampling module with a preset bridge arm current threshold; when the bridge arm current exceeds the bridge arm current threshold, the control module controls the switch module to disconnect and outputs a turn-off signal to the signal control terminal of the power semiconductor device.

[0026] Specifically, the drive circuit also integrates overcurrent protection, including a first current sampling module and a first comparison unit. The first current sampling module is used to collect the arm current of the power semiconductor device. The first current sampling module can be set in the emitter or source circuit of the power device, for example, by using a series sampling resistor, current transformer or Hall current sensor. The arm current reflects the magnitude of the current flowing through the power device itself and is the direct basis for judging whether an overcurrent or short circuit fault has occurred. The first comparison unit is integrated inside the control module, and its input terminal is connected to the output terminal of the first current sampling module. It is used to compare the collected arm current with a preset arm current threshold. The threshold can be preset according to the rated current and safe operating area of ​​the power device, for example, set to 1.5 to 2 times the rated current.

[0027] In this embodiment, when the first comparison unit determines that the bridge arm current exceeds a preset threshold, the control module first controls the switching module to disconnect, immediately cutting off the path between the second positive power supply module and the positive power supply terminal, causing the driving voltage to drop from high voltage to the lower voltage provided by the first positive power supply module, avoiding the power device from being turned off under high voltage and preventing the fault current from further expanding; then, a turn-off signal is output, that is, the control module outputs a turn-off signal to the signal control terminal of the power semiconductor device, reliably turning off the power device; the overcurrent protection also follows the principle of first cutting off the low voltage and then turning off the device, ensuring the safety of the fault turn-off process; based on this, by integrating the bridge arm current sampling and comparison protection functions, the drive circuit can achieve a fast and safe protection response when an overcurrent or short circuit fault occurs. Compared with the traditional solution of directly turning off under high voltage, this application actively cuts off the high voltage source before turning off, effectively suppressing the rise rate of the fault current, reducing the turn-off stress of the power device, and significantly improving the fault tolerance and reliability of the system.

[0028] Specifically, in the above embodiments, the driving circuit further includes a driver, the signal input terminal of which is connected to the output terminal of the control module, the signal output terminal of which is connected to the gate of the power semiconductor device, and the power input terminal of which is connected to the positive power supply terminal and the negative power supply terminal respectively; the driver is used to couple the driving voltage provided by the positive power supply terminal or the turn-off negative voltage provided by the negative power supply terminal to the gate of the power semiconductor device based on the control of the control module.

[0029] Specifically, the drive circuit also includes a driver, which serves as the power interface between the control module and the power semiconductor device. The driver typically contains a power amplification stage and an output stage circuit. Its core function is to selectively amplify the drive voltage provided by the positive power supply terminal or the turn-off negative voltage provided by the negative power supply terminal based on the low-voltage logic signal input from the control module, and then couple it to the gate of the power semiconductor device. Specifically, when the control module issues an on command, the driver applies the voltage from the positive power supply terminal to the gate, turning on the power device. This may be due to the first positive power supply module supplying power alone or the second positive power supply module supplying power. Conversely, when the control module issues a turn-off command, the driver applies the turn-off negative voltage from the negative power supply terminal to the gate, turning off the power device.

[0030] In this embodiment, by setting an independent driver between the control module and the power semiconductor device, the isolation and matching of the low-voltage control signal and the high-voltage drive power are achieved. The driver can provide sufficient peak drive current to ensure the rapid charging and discharging of the gate capacitor of the power device, thereby achieving rapid turn-on and turn-off. At the same time, the driver isolates the control module from the high-voltage main circuit, improving the system's anti-interference capability and reliability.

[0031] In some embodiments, in certain high-voltage or high-reliability applications, electrical isolation is required between the control module and the main power circuit. This function can be achieved by using an isolation driver. For example, an optocoupler isolator can be connected in series between the control module and the driver. The turn-on or turn-off signal output by the control module first drives the light-emitting diode of the optocoupler, and then the photosensitive receiver of the optocoupler transmits the signal to the input terminal of the driver. The optocoupler isolation scheme has low cost, mature technology, and is suitable for medium-frequency applications.

[0032] Specifically, in the above embodiment, a slope control resistor is connected in series between the switching module and the second positive power supply module. The slope control resistor is used to control the voltage rise slope of the positive power supply terminal after switching from the first driving positive voltage to the second driving positive voltage.

[0033] In this embodiment, the slope control resistor is connected in series between the output terminal of the second positive power supply module and the input terminal of the switching module. When the switching module is in the closed state, the second driving positive voltage output by the second positive power supply module is transmitted to the positive power supply terminal via the switching module and the slope control resistor, and then acts on the gate of the power semiconductor device. Specifically, considering that the positive power supply terminal was originally clamped by the first positive power supply module to the first driving positive voltage, while the output voltage of the second positive power supply module is higher, there is a voltage difference between the two. Without the slope control resistor, at the moment the switching module is closed, the voltage at the positive power supply terminal would be... The instantaneous jump from the first driving positive voltage to the second driving positive voltage produces a theoretical step response. In actual circuits, due to the presence of parasitic inductance and gate capacitance, this transient jump can cause voltage overshoot and ringing, potentially causing stress on the gate oxide layer of power devices. However, by connecting a slope control resistor in series, an RC charging circuit is formed with the equivalent capacitance at the positive power supply terminal. When the switching module is closed, the voltage at the positive power supply terminal no longer jumps instantaneously, but rises smoothly according to the exponential law of the RC charging circuit. The larger the resistance of the slope control resistor, the slower the voltage rises.

[0034] A second aspect of the present invention provides a power semiconductor driving system, comprising: an H-bridge inverter circuit, including a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first power transistor and a second power transistor connected in series, and the second bridge arm includes a third power transistor and a fourth power transistor connected in series, wherein the gates of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor are respectively connected to a driving circuit as described above; a load connected between the first bridge arm and the second bridge arm; and a coordination module connected to the control modules of the four driving circuits respectively, for providing synchronous control commands to the control modules.

[0035] The power semiconductor driving system provided by this invention allows each power transistor to be powered independently by a first positive power supply module in its respective driving circuit during its turn-on transient process, achieving safe turn-on with a lower gate voltage and avoiding voltage spikes. After entering the conduction steady state, a second positive power supply module is connected through a switching module, enabling the second positive power supply module to provide a higher driving voltage to the gate, significantly reducing the on-state voltage drop and conduction losses. Before the start of the turn-off transient process, the switching module is disconnected in advance, resuming independent power supply from the first positive power supply module, achieving rapid turn-off with a lower gate voltage and avoiding prolonged turn-off time. Thus, the system achieves time-division dynamic control of the driving voltage of each power transistor in the H-bridge inverter topology, effectively reducing the overall conduction losses of the system and improving the conversion efficiency while ensuring switching safety and turn-off reliability.

[0036] Specifically, in the above embodiments, the drive system further includes: a second current sampling module for collecting the load current of the load; the coordination module further includes a second comparison unit connected to the second current sampling module for comparing the load current collected by the second current sampling module with a preset load current threshold; when the load current exceeds the load current threshold, the coordination module outputs a global shutdown command to the control modules in all drive circuits, so that the control modules in the drive circuits control the corresponding switching modules to disconnect according to the global shutdown command, and output a shutdown signal to shut down the corresponding power semiconductor device.

[0037] In this embodiment, the power semiconductor drive system also integrates a system-level overcurrent protection function, specifically including a second current sampling module and a second comparison unit disposed within the coordination module. The second current sampling module is used to collect the current flowing through the load. Unlike the first current sampling module, the second current sampling module monitors the load current at the output of the entire H-bridge inverter circuit, reflecting the overall output state of the system. In addition, the second current sampling module can be set at any position in the load loop. For example, a sampling resistor can be connected in series between the H-bridge output and the load. A current transformer or Hall current sensor can be used to collect the load current non-contactly. The second comparison unit is integrated inside the coordination module, with its input terminal connected to the output terminal of the second current sampling module. It is used to compare the collected load current with a preset load current threshold. The threshold can be preset according to the system's rated output current and safe operating range, and is usually set to 1.2 to 1.5 times the rated current. Unlike the bridge arm current threshold, the load current threshold is used to detect system-level continuous overload or output-side faults.

[0038] Furthermore, when the second comparison unit determines that the load current exceeds the preset threshold, the coordination module outputs a global shutdown command. The coordination module simultaneously sends a global shutdown command to the control modules in all four drive circuits. The command has the highest priority and can cover the timing control logic of each drive circuit. After receiving the global shutdown command, the control module in each drive circuit controls the switching module in its drive circuit to disconnect, cuts off the second positive power supply module, causes the drive voltage to drop back to the lower voltage provided by the first positive power supply module, and outputs a shutdown signal to the signal control terminal of the corresponding power semiconductor device to reliably turn off the power transistor.

[0039] In the system provided in this application, the overcurrent protection function and the bridge arm current protection function work together. When a single power transistor is short-circuited, the first current sampling module responds quickly, turning off only the faulty phase power transistor, while the other power transistors can still operate normally. When a load overload or output-side fault occurs, the second current sampling module triggers global protection, simultaneously turning off all power transistors to prevent the fault from escalating. Based on this, the load current protection can detect fault types that cannot be covered by a single bridge arm current sampling, providing more comprehensive safety protection for the system. It also forms a hierarchical protection system with the bridge arm current protection. Minor overload triggers early warning or current limiting, while severe overload or short circuit triggers global shutdown. Under the premise of ensuring safety, unnecessary system downtime is avoided as much as possible. Furthermore, the coordination module issues a unified global shutdown command to ensure that the four power transistors are turned off synchronously, avoiding voltage spikes or current imbalances caused by inconsistent turn-off times of the power transistors.

[0040] like Figure 2 As shown in the figure, an embodiment of the application provides a power semiconductor driving system, including an H-bridge inverter circuit, a load, and four identical driving circuits. The H-bridge inverter circuit includes a first power transistor Q1, a second power transistor Q2, a third power transistor Q3, and a fourth power transistor Q4. The first power transistor Q1 and the second power transistor Q2 are connected in series to form a first bridge arm, and the third power transistor Q3 and the fourth power transistor Q4 are connected in series to form a second bridge arm. The load is connected between the first and second bridge arms. All four power transistors are either IGBTs or MOSFETs, and each power transistor is connected to an independent driving circuit. The figure shows the internal structure of the driving circuit for the second power transistor Q2 as an example; the driving circuit structures for the other three power transistors are identical.

[0041] Taking the driving circuit of the second power transistor Q2 as an example, it mainly includes: positive power supply terminal Vcc, negative power supply terminal Vee, first positive power supply module Vcc1, second positive power supply module Vcc2, switching module, slope control resistor Rs, control module, and driver. The overall circuit structure can be broken down into the following parts: First, the power supply terminals. The positive power supply terminal Vcc provides a positive drive voltage to the gate of the second power transistor Q2 and is the convergence point of the drive voltage. The negative power supply terminal Vee provides a negative turn-off voltage, such as -5V to -15V, to the gate of the second power transistor Q2, ensuring that the second power transistor Q2 is turned off during the turn-off period. Reliable cutoff and prevention of false triggering; secondly, the positive power supply modules, the output of the first positive power supply module Vcc1 is directly connected to the positive power supply terminal Vcc to provide the first driving positive voltage, for example +15V, which is relatively low and used for the power transistor's turn-on transient process and the pre-turn-off stage. The output of the second positive power supply module Vcc2 is connected to the positive power supply terminal Vcc through a series slope control resistor Rs and the switching module S2 to provide the second driving positive voltage. The amplitude of the second driving positive voltage is higher than the first driving positive voltage, for example +18V or higher, and is used to output to the gate during the power transistor's conduction steady-state stage to reduce the on-state voltage drop; then... The switching module contains a core switching circuit S2, in which a semiconductor switching device is connected in series between the second positive power supply module Vcc2 and the positive power supply terminal Vcc. This circuit controls the on / off state between Vcc2 and Vcc. The semiconductor switching device can be a MOSFET, IGBT, or transistor. The control terminal is connected to the output of the control module. A slope control resistor Rs is also connected in series between Vcc2 and the switching circuit S2. Rs and the equivalent capacitance of the positive power supply terminal form an RC charging circuit, used to control the voltage at the positive power supply terminal Vcc from the first... The voltage rise slope after switching from the first driving positive voltage to the second driving positive voltage is used to suppress voltage spikes and ringing. In addition, there is a control module, which is the core logic unit of the drive circuit. It is mainly used to receive external input turn-on and turn-off signals, generate time base signals corresponding to the working state of the power transistor, output switch control signals to the switching circuit S2 to control its opening or closing, and output turn-on or turn-off commands to the driver. The control module integrates a timing unit and a comparison unit. The timing unit is used to generate time bases corresponding to the turn-on transient state, the conduction steady state, and the turn-off transient state. The comparison unit is connected to the first current sampling module.In addition, the driver serves as the power interface between the control module and the power transistor. Its signal input terminal connects to the output terminal of the control module to receive on / off commands. Its power input terminal connects to the positive power supply terminal Vcc and the negative power supply terminal Vee, respectively, to obtain the energy required for driving. Its signal output terminal connects to the gate of the second power transistor Q2, outputting the amplified drive voltage. Based on the control module's on / off command, the driver couples the voltage at the positive power supply terminal Vcc (possibly powered by Vcc1 alone or Vcc2) to the gate of the second power transistor Q2; or based on the off / off command, it couples the negative voltage at the negative power supply terminal Vee to the gate of the second power transistor Q2. Finally, there is a current sampling module. The first current sampling module is located in the bridge arm circuit of the second power transistor Q2, for example, in the second power transistor Q2's... An emitter or source series sampling resistor is used to collect the bridge arm current Ic flowing through the second power transistor Q2. The sampled signal is sent to the comparator unit inside the control module for fast overcurrent protection of a single power transistor. The second current sampling module is set in the load circuit, for example, a current transformer or Hall sensor is connected in series between the load and the H-bridge output to collect the load current. The sampled signal is sent to the second comparator unit inside the coordination module for system-level overload protection. Based on this, the control modules of the four drive circuits are all connected to a common coordination module to provide synchronous turn-on or turn-off commands to each control module, ensuring that each power transistor of the H-bridge operates in the correct timing, and to receive the load current signal from the second current sampling module. When a system overload is detected, a global turn-off command is issued to all control modules.

[0042] Furthermore, taking the second power transistor Q2 as an example, the working process of a single driving circuit is described in detail. The working principle of the other three power transistors is exactly the same. Under normal operating timing, four timing parameters are given first, where t0 is the time when the turn-on signal is issued, t1 is the time when the turn-on transient process ends, at which time the second power transistor Q2 is fully turned on, t2 is the preparation time before turn-off, that is, the time when the switching circuit S2 is turned off, and t3 is the time when the turn-off signal is issued.

[0043] Based on the above four timing parameters, the process is divided into the following stages: The first stage is the turn-on transient process, from time t0 to t1. The external system or coordination module sends a turn-on signal to the control module. After receiving the turn-on signal, the control module outputs a turn-off command to the switching circuit S2, keeping the switching circuit S2 in the off state. At this time, the path between the second positive power supply module Vcc2 and the positive power supply terminal Vcc is cut off. The positive power supply terminal Vcc is only powered by the first positive power supply module Vcc1, with a lower first drive positive voltage of +15V. The control module sends a turn-on command to the driver, and the driver couples the voltage of the positive power supply terminal Vcc +15V to the gate of the second power transistor Q2, and the second power transistor Q2 begins to conduct. In this stage, due to the use of a lower drive voltage, gate voltage spikes caused by parasitic inductance and Miller capacitance effects during the switching process are avoided, ensuring turn-on safety.

[0044] The second stage is the steady-state conduction stage, from time t1 to t2. The timing unit inside the control module detects the end of the turn-on transient process, i.e., the preset time t1 is reached. The second power transistor Q2 is fully turned on. The control module outputs a closing command to the switching circuit S2. The switching circuit S2 closes, and the output voltage +18V of the second positive power supply module Vcc2 is transmitted to the positive power supply terminal Vcc through the slope control resistor Rs and the closed switching circuit S2. Due to the presence of the slope control resistor Rs, the voltage at the positive power supply terminal Vcc rises smoothly from +15V to the switched voltage, i.e., close to +18V, according to the law of the RC charging curve. The resistance value of the slope control resistor Rs determines the voltage rise slope. The control module continues to send turn-on commands to the driver. The driver couples the raised positive power supply terminal voltage to the gate of the second power transistor Q2. The gate voltage of the second power transistor Q2 increases. After the gate voltage increases, the on-state voltage drop of the second power transistor Q2 is significantly reduced, and the conduction loss is reduced accordingly, thereby improving the system efficiency.

[0045] The third stage is the pre-shutdown preparation stage, from time t2 to t3. The timing unit inside the control module detects that the shutdown transient process is about to begin, that is, the preset time t2 is reached. t2 is a preset time earlier than the arrival time of the external shutdown signal. The control module outputs a disconnect command to the switching circuit S2. The path between the second positive power supply module Vcc2 and the positive power supply terminal Vcc is cut off. The positive power supply terminal Vcc is restored to being powered solely by the first positive power supply module Vcc1. The voltage drops back to +15V. The control module continues to send turn-on commands to the driver or maintain the current state. The second power transistor Q2 continues to conduct, but the gate voltage has dropped to a lower level.

[0046] The fourth stage is the turn-off transient process. After time t3, the external system or coordination module sends a turn-off signal to the control module. After receiving the turn-off signal, the control module sends a turn-off command to the driver. The driver couples the turn-off negative voltage of the negative power supply terminal Vee, for example -8V, to the gate of the second power transistor Q2. The gate voltage of the second power transistor Q2 is quickly pulled down to a negative voltage, and the second power transistor Q2 is reliably turned off. Since the lower positive drive voltage has been switched back in advance before the turn-off, the turn-off process will not be prolonged due to excessive voltage, and the turn-off loss is controlled at a low level.

[0047] Furthermore, this application provides bridge arm current overcurrent protection for a single power transistor. A first current sampling module collects the bridge arm current Ic of the second power transistor Q2 in real time and sends the current detection signal to a first comparison unit inside the control module. The first comparison unit compares the bridge arm current Ic with a preset bridge arm current threshold, which is typically 1.5 times the rated current. When the bridge arm current Ic exceeds the threshold, the control module outputs a disconnect command to the switching circuit S2, immediately cutting off the second positive power supply module Vcc2. The positive power supply terminal Vcc drops back to the lower voltage of Vcc1, and a turn-off command is sent to the driver. The driver couples the turn-off negative voltage of the negative power supply terminal Vee to the gate of the second power transistor Q2, turning off the second power transistor Q2. This protection action has a higher priority than normal timing control and can complete fault response within microseconds, effectively preventing... The power transistor was damaged due to overcurrent. In addition, this application can also realize load current overcurrent protection for the entire system. The second current sampling module collects the load current in real time and sends the current detection signal to the second comparison unit inside the coordination module. The second comparison unit compares the load current with the preset load current threshold. The load current threshold is usually 1.2 times the rated current. When the load current exceeds the threshold, the coordination module outputs a global shutdown command to the control modules of all four drive circuits. After receiving the global shutdown command, each control module synchronously performs the following actions: first, it controls the switching circuit S2 of its own drive circuit to open, cuts off its corresponding second positive power supply module Vcc2, sends a shutdown command to the driver of its own drive circuit, and shuts down the corresponding power transistor. Thus, it can simultaneously shut down all power transistors in the event of system-level overload or output-side fault to prevent the fault from spreading.

[0048] In addition, during normal inverter operation, the coordination module sends synchronous PWM control signals to the control modules of the four drive circuits, causing the first power transistor Q1 and the fourth power transistor Q4 to be turned on simultaneously and the second power transistor Q2 and the third power transistor Q3 to be turned off simultaneously, or the second power transistor Q2 and the third power transistor Q3 to be turned on simultaneously and the first power transistor Q1 and the fourth power transistor Q4 to be turned off simultaneously, thereby forming an AC voltage on the load. The drive circuit of each power transistor independently executes the above time-sharing power supply control, that is, each power transistor is powered by the first positive power supply module Vcc1 alone during its own turn-on transient process, and is connected to the second positive power supply module Vcc2 after entering the turn-on steady state to reduce conduction losses. Before turn-off, it switches back to the first positive power supply module Vcc1 in advance to ensure turn-off speed. Since the coordination module provides synchronous turn-on / turn-off signals, the drive timing of each power transistor is synchronized with the overall commutation process of the H-bridge, ensuring normal system operation.

[0049] A third aspect of the present invention provides a power semiconductor driving circuit control method, which is applied to the power semiconductor driving circuit of any of the above claims. The method includes: acquiring the conduction pulse width time corresponding to the turn-on command; determining whether the conduction pulse width time is less than or equal to a preset minimum conduction time threshold; when the conduction pulse width time is less than or equal to the minimum conduction time threshold, maintaining the switching module in an off state, and providing a first driving voltage to the gate of the power semiconductor device by a first positive power supply module until it is turned off; when the conduction pulse width time is greater than the minimum conduction time threshold, controlling the first positive power supply module after the power semiconductor device receives an externally input turn-on signal. A first driving positive voltage is output to the gate of the power semiconductor device; at a first preset time after receiving the turn-on signal, the control switch module switches to the closed state, controls the second positive power supply module to connect, and causes the second positive power supply module to output a second driving positive voltage to the gate of the power semiconductor device; at a second preset time after receiving the turn-on signal, or when receiving an externally input turn-off signal, the control switch module returns to the open state, and the first driving positive voltage is resumed to be output to the gate of the power semiconductor device by the first positive power supply module, wherein the second preset time is earlier than the end time of the conduction pulse width; after the second positive power supply module is turned off, the power semiconductor device is turned off.

[0050] Specifically, in the above embodiments, the method further includes: sampling the bridge arm current of the power semiconductor device; comparing the sampled bridge arm current with a preset bridge arm current threshold; when the bridge arm current exceeds the bridge arm current threshold, controlling the second positive power supply module to disconnect and controlling the first positive power supply module to supply power, while controlling the control module to output a shutdown signal to shut down the power semiconductor device.

[0051] like Figure 3 As shown, the control method specifically consists of the following steps: After system initialization, the control module receives an external activation command and obtains the conduction pulse width time corresponding to this activation command.

[0052] Step 1 involves pulse width determination, checking if the conduction pulse width time is greater than the preset minimum conduction time threshold Ton_min. If the conduction pulse width time is less than or equal to Ton_min, it indicates a narrow pulse, and a short pulse process is executed, meaning the switching circuit S2 remains open throughout the entire process, with only the first positive power supply module Vcc1 providing the drive voltage to the gate until the end of the current conduction cycle. At this point, the control module issues a turn-off signal, the power transistor turns off, and the process ends. If the conduction pulse width time is greater than Ton_min, it indicates a sufficiently long pulse, and a long pulse process is executed, proceeding to Step 2.

[0053] Step 2 involves powering on and supplying power to Vcc1. The control module issues a power-on command while keeping the control switch circuit S2 open. At this time, only the first positive power supply module Vcc1 supplies power to the positive power supply terminal Vcc. The driver couples a lower first drive voltage to the gate of the power transistor, and the power transistor begins to conduct.

[0054] Step 3 is to wait for the first preset time t1. The internal timer of the control module starts counting from time 0, that is, when the turn-on signal is issued, and determines whether the current time has reached the first preset time t1. Here, t1 is set to be greater than the actual turn-on process ton of the power transistor to ensure that the power transistor has been fully turned on. If the first preset time t1 has not been reached, the state of step 2 is maintained. If the first preset time t1 is reached, step 4 is executed.

[0055] Step 4 involves connecting Vcc2. The control module controls the switch circuit S2 to close, and the second positive power supply module Vcc2 is connected to the positive power supply terminal Vcc through the slope control resistor Rs. At this time, the voltage at the positive power supply terminal Vcc smoothly rises from Vcc1 to Vcc2, the gate voltage increases, and the on-state voltage drop and conduction loss are significantly reduced.

[0056] Step 5 involves waiting for the second preset time t2. The control module continues timing to determine whether the current time has reached the second preset time t2 or whether an external shutdown signal has been received. The second preset time t2 is set to be earlier than the end time of the current conduction pulse width, i.e., the advance before shutdown. If the second preset time t2 has not been reached and no shutdown signal has been received, the high-voltage drive state of step 4 is maintained. If the second preset time t2 has been reached or a shutdown signal has been received, step 6 is executed.

[0057] Step 6 is to switch back to Vcc1. The control module controls the switch circuit S2 to disconnect, cutting off the second positive power supply module Vcc2. The positive power supply terminal Vcc is then powered solely by the first positive power supply module Vcc1, and the gate voltage drops back to the lower first drive positive voltage.

[0058] Step 7 is the power transistor turn-off. The control module sends a turn-off command to the driver, and the driver couples the turn-off negative voltage of the negative power supply terminal Vee to the gate, so that the power transistor is reliably turned off. At this point, a complete switching cycle ends.

[0059] Based on the above-mentioned normal timing control, this control method also integrates a bridge arm current overcurrent protection function. This protection process has the highest priority and can interrupt the normal timing and execute protection actions at any time. At any stage of the power device's operation, the first current sampling module continuously collects the bridge arm current Ic of the power semiconductor device and sends the current detection signal to the first comparison unit inside the control module in real time. The first comparison unit compares the collected bridge arm current with a preset bridge arm current threshold in real time. If the bridge arm current does not exceed the threshold, the system continues to execute the normal timing control process and does not trigger protection actions. If the bridge arm current exceeds the threshold, it indicates that an overcurrent or short circuit has occurred. Upon failure, the control module immediately triggers protection actions, performing overcurrent protection. When the bridge arm current exceeds the preset threshold, the control module outputs a disconnect command with the highest priority, instantly disconnecting the control switch module and cutting off the second positive power supply module from the circuit. The positive power supply terminal immediately drops back to the lower voltage level supplied solely by the first positive power supply module. Simultaneously with disconnecting Vcc2, the control module outputs a shutdown signal to the power semiconductor device. The driver couples the shutdown negative voltage at the negative power supply terminal to the gate, reliably shutting down the power device. After the power device is shut down, the system can enter a fault-locked state or automatically attempt recovery according to the configuration. Fault information can be recorded and reported to the upper-level system.

[0060] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A driving circuit for a power semiconductor, characterized in that, include: The positive power supply terminal is used to provide a positive drive voltage to the gate of power semiconductor devices; The first positive power supply module has its output terminal connected to the positive power supply terminal and is used to output the first driving positive voltage; The second positive power supply module has its output terminal connected to the positive power supply terminal via a switching module, and is used to output a second driving positive voltage, wherein the second driving positive voltage is higher than the first driving positive voltage; The switching module is connected in series between the second positive power supply module and the positive power supply terminal, and is used to control the on / off state between the second positive power supply module and the positive power supply terminal. When the switching module is in the off state, the first driving positive voltage is output to the gate of the power semiconductor device. When the switching module is in the closed state, the second driving positive voltage is output to the gate of the power semiconductor device. The negative power supply terminal is used to provide a negative turn-off voltage to the gate of power semiconductor devices; The control module is connected to the signal control terminals of the switch module and the power semiconductor device, respectively. It is used to control the switch module to remain in the off state during the turn-on transient process of the power semiconductor device, control the switch module to switch to the closed state after the power semiconductor device enters the conduction steady state, and control the switch module to return to the off state before the turn-off transient process of the power semiconductor device begins.

2. The driving circuit for power semiconductors according to claim 1, characterized in that, The switching module includes a semiconductor switching device. The control terminal of the semiconductor switching device is connected to the output terminal of the control module. The first connection terminal of the semiconductor switching device is connected to the output terminal of the second positive power supply module, and the second connection terminal of the semiconductor switching device is connected to the positive power supply terminal.

3. The driving circuit for the power semiconductor according to claim 1 or 2, characterized in that, The control module includes: The drive signal receiving end is used to receive external input turn-on and turn-off signals; A timing unit is used to generate time reference signals corresponding to the turn-on transient process, conduction steady state, and turn-off transient process of the power semiconductor device. The output terminal is connected to the control terminal of the switch module and is used to output a corresponding switch control signal based on the on or off signal received by the drive signal receiving terminal and the time reference signal generated by the timing unit. The switch control signal is used to control the on / off state of the switch module.

4. The power semiconductor driving circuit according to claim 3, characterized in that, It also includes a first current sampling module, which is used to collect the bridge arm current of the power semiconductor device; The control module further includes a first comparison unit, which is connected to the first current sampling module and is used to compare the arm current collected by the first current sampling module with a preset arm current threshold. When the bridge arm current exceeds the bridge arm current threshold, the control module controls the switch module to disconnect and outputs a shutdown signal to the signal control terminal of the power semiconductor device.

5. The driving circuit for power semiconductors according to claim 1, characterized in that, Also includes: The driver has its signal input terminal connected to the output terminal of the control module, its signal output terminal connected to the gate of the power semiconductor device, and its power input terminal connected to the positive power supply terminal and the negative power supply terminal, respectively. The driver is used to couple the drive voltage provided by the positive power supply terminal or the turn-off negative voltage provided by the negative power supply terminal to the gate of the power semiconductor device based on the control of the control module.

6. The driving circuit for power semiconductors according to claim 1, characterized in that, A slope control resistor is also connected in series between the switching module and the second positive power supply module. The slope control resistor is used to control the voltage rise slope of the positive power supply terminal after switching from the first driving positive voltage to the second driving positive voltage.

7. A power semiconductor driving system, characterized in that, include: The H-bridge inverter circuit includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first power transistor and a second power transistor connected in series, the second bridge arm includes a third power transistor and a fourth power transistor connected in series, and the gates of the first power transistor, the second power transistor, the third power transistor and the fourth power transistor are respectively connected to a drive circuit as described in any one of claims 1 to 6. The load is connected between the first bridge arm and the second bridge arm; The coordination module is connected to the control modules of the four drive circuits respectively, and is used to provide synchronous control commands to the control modules.

8. The power semiconductor driving system according to claim 7, characterized in that, Also includes: The second current sampling module is used to collect the load current of the load; The coordination module further includes a second comparison unit, which is connected to the second current sampling module and is used to compare the load current collected by the second current sampling module with a preset load current threshold. When the load current exceeds the load current threshold, the coordination module outputs a global shutdown command to the control modules in all the drive circuits, so that the control modules in the drive circuits control the corresponding switching modules to disconnect according to the global shutdown command, and output a shutdown signal to shut down the corresponding power semiconductor devices.

9. A power semiconductor drive circuit control method, characterized in that, The method is applied to a driving circuit of a power semiconductor as described in any one of claims 1 to 6, and the method includes: Obtain the conduction pulse width time corresponding to the activation command, and determine whether the conduction pulse width time is less than or equal to a preset minimum conduction time threshold. When the conduction pulse width time is less than or equal to the shortest conduction time threshold, the switching module is kept in the off state, and the first positive power supply module provides a first driving positive voltage to the gate of the power semiconductor device until it is turned off. When the conduction pulse width time is greater than the shortest conduction time threshold, after the power semiconductor device receives an externally input turn-on signal, the first positive power supply module is controlled to output a first driving positive voltage to the gate of the power semiconductor device. At a first preset moment after receiving the activation signal, the switch module is controlled to switch to the closed state, and the second positive power supply module is controlled to connect, so that the second positive power supply module outputs a second driving positive voltage to the gate of the power semiconductor device; At a second preset time after receiving the turn-on signal, or when receiving an externally input turn-off signal, the switch module is controlled to return to the off state, and the first positive power supply module outputs the first driving positive voltage to the gate of the power semiconductor device. The second preset time is earlier than the end time of the turn-on pulse width. After the second positive power module is disconnected, the power semiconductor device is controlled to turn off.

10. The power semiconductor drive circuit control method according to claim 1, characterized in that, The method further includes: Sample the bridge arm current of the power semiconductor device; The sampled bridge arm current is compared with the preset bridge arm current threshold. When the bridge arm current exceeds the bridge arm current threshold, the second positive power supply module is controlled to disconnect, and the first positive power supply module is controlled to supply power. At the same time, the control module is controlled to output a shutdown signal to shut down the power semiconductor device.

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