A turn-off driving device, an electrical apparatus, and a turn-off driving method

Abstract

The application provides a turn-off driving device, an electrical device and a turn-off driving method. The output level is switched from high level to low level and lasts for a first time length, so that the gate voltage is lowered from high level to the Miller plateau or close to the Miller plateau. Then, the output is controlled to be in high resistance state and lasts for a second time length, so that the gate voltage is close to the critical saturation voltage, i.e. at the first plateau level. At this time, the voltage value of the gate voltage and the output level value of the driving circuit are both the first plateau level. Finally, the output level is switched from the first plateau level to low level, so that the gate voltage is switched from the first plateau level to low level, so as to turn off the switch device. The application utilizes the Miller plateau effect of the switch device, and adaptively adjusts the gate voltage from high level to the critical saturation voltage, which can effectively reduce the turn-off loss, and the output of the driving circuit does not need to be dynamically adjusted with the change of the turn-off current, and the implementation of the driving circuit is relatively simple.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a shutdown drive device, electrical equipment, and shutdown drive method. Background Technology

[0002] Currently, electrical equipment such as power converters typically contain multiple switching devices. As the switching frequency of these devices increases, the proportion of switching losses in the total losses also increases. Reducing the switching losses of these devices can effectively improve the power conversion efficiency of electrical equipment and reduce the difficulty of system heat dissipation design.

[0003] Switching losses in switching devices include turn-on losses and turn-off losses. Turn-off losses can be optimized from multiple dimensions, including circuit topology, driving technology, and modulation technology. Regarding driving technology, existing technologies focus on the dynamic adjustment of the gate current during turn-off. This is mainly achieved by using appropriate turn-off resistors under different load conditions to balance voltage stress and turn-off losses. The optimization logic for turn-off losses essentially involves increasing the turn-off speed with a smaller turn-off resistor or a larger gate current, thereby reducing turn-off losses. However, this method has limited effectiveness in reducing turn-off losses. Once the turn-off resistor is reduced to a certain value, its impact on the turn-off speed diminishes, and further reductions in the turn-off resistor value cannot effectively reduce turn-off losses.

[0004] Studies have found that adjusting the gate voltage to near the critical saturation voltage before turning off the switching device, and maintaining this position for a period of time, significantly increases the turn-off speed and reduces turn-off losses. However, the critical saturation voltage changes with the switching device's turn-off current. Because the turn-off current of the switching device dynamically changes during operation, it is difficult to accurately adjust the gate voltage to the critical saturation voltage before the device is turned off. Summary of the Invention

[0005] This application provides a turn-off drive device, electrical equipment, and turn-off drive method to reduce the turn-off losses of switching devices.

[0006] Firstly, this application provides a turn-off driving device, including a driving circuit. The driving circuit is used to connect to the control terminal and the output terminal of a switching device, and to control the output terminal level to adjust the gate voltage between the control terminal and the output terminal, thereby turning off the switching device. Specifically, the switching device may be a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT). The MOSFET includes a gate, a source, and a drain, and the IGBT includes a gate, a collector, and an emitter. In this application, the gates of the MOSFET and IGBT can be referred to as the control terminals of the switching device, the drain of the MOSFET and the collector of the IGBT can be referred to as the input terminals of the switching device, and the source of the MOSFET and the emitter of the IGBT can be referred to as the output terminals of the switching device. Specifically, in a process of turning off the switching device: the driving circuit controls the output terminal level to switch from a high level to a low level, and continuously outputs a low level for a first duration, so that the gate voltage drops from a high level. Subsequently, the drive circuit controls the output to be in a high-impedance state for a second duration, causing the gate voltage to approach the critical saturation voltage, i.e., the gate voltage to be at the first plateau level. At this point, the gate voltage value is the same as the output level of the drive circuit. Therefore, it can be considered that the output level of the drive circuit remains at the first plateau level for the second duration, and the gate voltage remains at the first plateau level for the third duration. The first plateau level is between high and low levels. The start time of the second duration is the end time of the first duration, the start time of the third duration is equal to or later than the start time of the second duration, and the end time of the third duration is the end time of the second duration. Finally, the control output level switches from the first plateau level to a low level, causing the gate voltage to switch from the first plateau level to a low level, thus turning off the switching device.

[0007] In this application, the high-impedance state of the drive circuit control output can be achieved by switching to a high-value drive resistor in the drive circuit. Alternatively, the high-impedance state of the drive circuit control output can be achieved by cutting off the current loop of the drive circuit. When the drive circuit control output is in a high-impedance state, the output level of the drive circuit is the same as the gate voltage of the switching device.

[0008] In this application, depending on the load rate of the electrical equipment where the turn-off drive is located, the waveform of the gate voltage will be in two different ways during the turn-off process of the switching device.

[0009] In the first scenario, when the drive circuit controls the output level to switch from high to low and maintains a low level for a first duration, the gate voltage drops from high to the Miller voltage (the second plateau level) and remains at that level for a fourth duration. The end of the fourth duration coincides with the end of the first duration. Afterward, the drive circuit controls the output to be in a high-impedance state for a second duration. This results in the drive circuit's output level remaining at the first plateau level for the second duration, while the gate voltage rises from the second plateau level to the first plateau level and remains at that level for a third duration. In this case, the start of the third duration is later than the start of the second duration, and the end of the third duration coincides with the end of the second duration.

[0010] In the above scenario, at the initial moment of switching off the switching device, the output level of the drive circuit changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage of the switching device from the high level of the on-state to the Miller voltage, thus initiating desaturation. At the second moment after the first time, the drive circuit controls the output to a high-impedance state for a duration of two times. This increases the output impedance of the drive circuit, making the gate voltage the same as the output level of the drive circuit. During this period, the current in the capacitor between the control and input terminals of the switching device changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, slightly increasing the gate voltage from the Miller voltage and bringing it closer to the critical saturation voltage, achieving an effective desaturation process. At the third moment after the second time, the drive circuit controls the output level to low, causing the gate voltage of the switching device to become low, thus turning off the switching device.

[0011] In the second scenario, under light load conditions (i.e., when the electrical equipment is under low load), as the drive circuit switches its output level from high to low and maintains a low level for a first duration, the gate voltage continuously decreases from high but does not reach the Miller voltage (the second plateau level). Before the gate voltage reaches the Miller voltage within the first duration, the drive circuit maintains a high impedance state for a second duration. This results in the drive circuit's output level remaining at the first plateau level for the second duration, and the gate voltage remaining at the first plateau level for a third duration. In this case, the start time of the third duration is equal to the start time of the second duration, and the end time of the third duration is equal to the end time of the second duration.

[0012] In the above scenario, at the initial moment of switching off the switching device, the output level of the drive circuit changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage of the switching device from the high level of the on-state, thus initiating desaturation. At the second moment after the first time, the drive circuit controls the output to a high-impedance state for a duration of two time. This increases the output impedance of the drive circuit, making the gate voltage the same as the output level of the drive circuit. During this period, the current in the capacitor between the control and input terminals of the switching device changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, thus bringing the gate voltage close to the critical saturation voltage and achieving an effective desaturation process. At the third moment after the second time, the drive circuit controls the output level to low, causing the gate voltage of the switching device to drop, thus turning off the switching device.

[0013] In this application, the driving circuit utilizes the Miller plateau effect of the switching device. First, by outputting a low level for a first duration, the gate voltage of the switching device reaches or approaches the Miller plateau. Then, by controlling the output to be in a high-impedance state for a second duration, the gate voltage of the switching device is adaptively adjusted from a high level to the critical saturation voltage through the Miller voltage, without having to dynamically adjust the output of the driving circuit according to the change of the turn-off current. The implementation of the driving circuit is relatively simple and can effectively reduce turn-off losses.

[0014] In some embodiments of this application, the shutdown drive device may further include a controller, which is used to output a control signal to the drive circuit. The drive circuit is used to control the output terminal level to switch from a high level to a low level according to the control signal and to continuously output a low level for a first duration, control the output terminal level to remain at a first plateau level for a second duration, and control the output terminal level to switch from the first plateau level to a low level.

[0015] In some embodiments of this application, the shutdown driving device may further include: a first sampling circuit and a first judgment circuit. The first sampling circuit is used to sample the current at the output terminal of the switching device for a first duration and a second duration; the first judgment circuit is used to output a first enable signal to the controller if the sampled current is greater than a first threshold. The controller is used to output a shutdown signal to the driving circuit in the next shutdown process of the switching device if it receives the first enable signal; if it does not receive the first enable signal, it outputs a control signal to the driving circuit. The driving circuit is used to: control the output terminal level to switch from a high level to a low level according to the control signal and output a low level for a first duration, control the output terminal level to remain at a first plateau level for a second duration, and control the output terminal level to switch from the first plateau level to a low level; or, control the output terminal level to switch from a high level to a low level according to the shutdown signal, so that the gate voltage drops from a high level to a low level. In this embodiment, based on the sampled current before shutdown, it is determined that the switching device is in an abnormal operating condition due to excessive current caused by factors such as load short circuit or device aging. In the next shutdown process, a conventional shutdown signal, i.e., a constant low-level signal, is used to directly switch the output level to a low level to shut down the switching device, thus ensuring normal shutdown of the control switching device. When it is determined that the switching device is in a normal operating condition based on the sampled current before shutdown, the control output level method provided in this application is used to shut down the switching device in the next shutdown process, which can reduce shutdown losses.

[0016] In some embodiments of this application, the turn-off driving device may further include: a second sampling circuit and a second judgment circuit. The second sampling circuit is used to: collect the voltage between the input and output terminals of the switching device. The second judgment circuit is used to: if the voltage is greater than a second threshold during a first duration and a second duration, output a second enable signal to the driving circuit. The driving circuit is used to: if the second enable signal is received, control the output terminal level to switch to a lower level. In this embodiment, when it is determined that the voltage is too high and an abnormal operating condition occurs, directly pulling the output terminal level down to a low level can prevent damage to the switching device and an increase in turn-off losses; when it is determined that the voltage of the switching device is in a normal operating condition, using the method of controlling the output terminal level provided in this application to control the switching device to turn off can reduce turn-off losses.

[0017] In some embodiments of this application, the second judgment circuit can also be used to output a second enable signal to the controller if the voltage is greater than a second threshold during the process of turning off each switching device. The controller is configured to: if it receives a first enable signal, maintain the first threshold unchanged in the next process of turning off the switching device; if it does not receive the first enable signal but receives the second enable signal, decrease the first threshold in the next process of turning off the switching device; if it does not receive either the first or the second enable signal, and if it did not receive either the first or the second enable signal in the previous multiple consecutive processes of turning off the switching devices, increase the first threshold in the next process of turning off the switching device; the maximum value of the first threshold is the initial value. In this embodiment, dynamically adjusting the first threshold based on the sampled voltage and current can reduce the situation where the drive circuit control output high impedance state is terminated due to abnormal voltage rise caused by device aging. For example, setting the initial value of the first threshold to 100A and using the method provided in this application to control the output level to turn off the switching device, no abnormality occurs. As switching devices age, their parameters drift. During a switch-off process, the sampled current may not show abnormalities, but the sampled voltage may. This indicates that using the current first threshold value will detect the abnormal voltage rise and terminate the high-impedance output state. Therefore, the first threshold value needs to be reduced, for example, to 90A. After reducing the first threshold value, if the sampled current and voltage during multiple consecutive switch-off processes are normal, the first threshold value can be appropriately increased, for example, to 95A. And so on.

[0018] In some embodiments of this application, the turn-off driving device may further include: a third sampling circuit, which is used to: acquire the voltage change rate between the input and output terminals of the switching device. The controller is used to: if the voltage change rate is greater than a third threshold, decrease the first duration or the second duration in the next turn-off process of the switching device; if the voltage change rate is less than or equal to the third threshold, increase the first duration or the second duration in the next turn-off process of the switching device. In this embodiment, when it is determined that the voltage change rate is greater than the third threshold, i.e., the efficiency rating, it indicates that the switching device may be aging, causing parameter drift and resulting in voltage increase. Therefore, in the next turn-off process of the switching device, the first duration or the second duration is decreased to reduce the abnormal operating condition of voltage increase during the turn-off control due to switching device aging. When it is determined that the voltage change rate is less than or equal to the third threshold, the first duration or the second duration is increased in the next turn-off process of the switching device to reduce turn-off losses.

[0019] In this application, the first duration can be considered as the period during which the gate voltage of the switching device adaptively adjusts to or near the Miller voltage, and the second duration is the desaturation time of the switching device. Therefore, in order to improve the turn-off efficiency of the switching device and reduce turn-off losses, the first duration is generally shorter than the second duration.

[0020] Secondly, this application provides an electrical device, including the shutdown drive device and switching device provided in the first aspect, wherein the switching device is used to connect or disconnect the electrical device from the load. The electrical device provided in the embodiments of this application can be a power conversion device such as an inverter or an uninterruptible power supply, and can be applied to power supply systems such as photovoltaic power generation systems and energy storage systems.

[0021] In some embodiments of this application, one or both of the first platform level and the second platform level can be adaptively adjusted, and one or both of the first platform level and the second platform level are positively correlated with the output power of the electrical equipment, that is, the greater the output power, the greater the values ​​of the first platform level and the second platform level.

[0022] Thirdly, this application provides a turn-off driving method, comprising: controlling the output terminal level to switch from a high level to a low level, and continuously outputting a low level for a first duration, so as to cause the gate voltage between the control terminal and the output terminal of the switching device to drop from a high level; then, controlling the output terminal level to remain at a first plateau level for a second duration, and controlling the gate voltage to remain at the first plateau level for a third duration, wherein the value of the first plateau level is between a high level and a low level; the start time of the second duration is the end time of the first duration, the start time of the third duration is equal to or later than the start time of the second duration, and the end time of the third duration is the end time of the second duration; finally, controlling the output terminal level to switch from the first plateau level to a low level, so as to cause the gate voltage to switch from the first plateau level to a low level, thereby turning off the switching device.

[0023] In this application, depending on the load rate of the electrical equipment, the waveform of the gate voltage will be in two different states during the process of turning off the switching device.

[0024] In the first scenario, when the control output level switches from high to low and remains low for a first duration, the gate voltage drops from high to the Miller voltage (the second plateau level) and remains low for a fourth duration. The end of the fourth duration coincides with the end of the first duration. Afterward, the control output is in a high-impedance state for a second duration, resulting in the output level remaining at the first plateau level for the second duration. Simultaneously, the gate voltage rises from the second plateau level to the first plateau level and remains at the first plateau level for a third duration. The start of the third duration is later than the start of the second duration, and the end of the third duration coincides with the end of the second duration.

[0025] In the above scenario, at the initial moment of switching off the device, the output level changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage from the high level (in the on-state) to the Miller voltage, causing the device to begin desaturation. At the second moment after the first time, the control output enters a high-impedance state for a duration of two times. This increases the output impedance, making the gate voltage equal to the output level. During this period, the current in the capacitor between the control and input terminals changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, slightly increasing the gate voltage from the Miller voltage and bringing it closer to the critical saturation voltage, thus achieving an effective desaturation process. At the third moment after the second time, the control output level returns to low, causing the gate voltage of the device to drop, effectively turning off the device.

[0026] In the second scenario, under light load conditions (i.e., when the electrical equipment is under low load), as the control output level switches from high to low and remains low for a first duration, the gate voltage continuously decreases from high but does not reach the Miller voltage (the second plateau level). Before the gate voltage reaches the Miller voltage within the first duration, the control output is in a high-impedance state for a second duration. This results in the output level remaining at the first plateau level for the second duration, and the gate voltage remaining at the first plateau level for a third duration. In this case, the start time of the third duration is equal to the start time of the second duration, and the end time of the third duration is equal to the end time of the second duration.

[0027] In the above scenario, at the initial moment of switching off the device, the output level changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage of the switching device from its high state (on-hand) to allow desaturation. At the second moment after the first time, the control output enters a high-impedance state for a duration of two times. This increases the output impedance, ensuring the gate voltage matches the output level. During this period, the current in the capacitor between the control and input terminals changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, bringing the gate voltage close to the critical saturation voltage and achieving an effective desaturation process. At the third moment after the second time, the control output level returns to low, causing the gate voltage of the switching device to drop, thus turning off the device.

[0028] In this application, the Miller plateau effect of the switching device is utilized. First, the gate of the switching device reaches or approaches the Miller plateau by maintaining a low output level for a first duration. Then, by controlling the output to be in a high impedance state for a second duration, the gate voltage of the switching device is adaptively adjusted from a high level to the critical saturation voltage without having to dynamically adjust the output of the drive circuit as the turn-off current changes. The drive circuit is relatively simple to implement and can effectively reduce turn-off losses.

[0029] In some embodiments of this application, the shutdown driving method may further include: sampling the current at the output terminal of the switching device for a first duration and a second duration. If the sampled current is greater than a first threshold, in the next shutdown process of the switching device, the output terminal level is controlled to switch from a high level to a low level, so that the gate voltage drops from a high level to a low level. If the current is less than or equal to the first threshold, in the next shutdown process of the switching device, the output terminal level is controlled to switch from a high level to a low level and continuously output at a low level for a first duration, the output terminal level is controlled to remain at a first plateau level for a second duration, and the output terminal level is controlled to switch from the first plateau level to a low level. In this embodiment, based on the sampled current before shutdown, it is determined that the switching device is in an abnormal operating condition due to excessive current caused by factors such as load short circuit or device aging. In the next shutdown process, a conventional shutdown signal, i.e., a constant low-level signal, is used to directly switch the output level to a low level to shut down the switching device, thus ensuring normal shutdown of the control switching device. When it is determined that the switching device is in a normal operating condition based on the sampled current before shutdown, the control output level method provided in this application is used to shut down the switching device in the next shutdown process, which can reduce shutdown losses.

[0030] In some embodiments of this application, the shutdown driving method may further include: acquiring the voltage between the input and output terminals of the switching device. During a first duration and a second duration, if the voltage exceeds a second threshold, the output terminal level is controlled to switch to a low level. In this embodiment, when an abnormal operating condition is determined to be due to excessive voltage, directly pulling the output terminal level down to a low level can prevent damage to the switching device and increase shutdown losses; when the voltage of the switching device is determined to be under normal operating conditions, using the method of controlling the output terminal level provided in this application to control the shutdown of the switching device can reduce shutdown losses.

[0031] In some embodiments of this application, the shutdown driving method may further include:

[0032] If the current is greater than the first threshold, the first threshold remains unchanged during the next switching device shutdown process. If the current is less than the first threshold and the voltage is greater than the second threshold, the first threshold is decreased during the next switching device shutdown process. If the current is less than the first threshold and the voltage is less than or equal to the second threshold, in the previous multiple switching device shutdown processes, if the current is less than the first threshold and the voltage is less than or equal to the second threshold, the first threshold is increased during the next switching device shutdown process. The maximum value of the first threshold is the initial value. In this embodiment, dynamically adjusting the first threshold based on the sampled voltage and current can reduce the occurrence of abnormal voltage rises due to device aging, which could lead to the termination of the control output high-impedance state. For example, if the initial value of the first threshold is set to 100A, and the switching device is shut down using the method provided in this application, no abnormality occurs. As the switching device is used, aging causes parameter drift. During a certain switching device shutdown process, the sampled current is not abnormal, but the sampled voltage is abnormal. This indicates that using the current first threshold for judgment will detect an abnormal voltage rise and terminate the control output high-impedance state. Therefore, the first threshold needs to be reduced, for example, to 90A. If, after decreasing the first threshold, the current and voltage sampled during the process of switching multiple devices off are all normal, the first threshold can be appropriately increased, for example, to 95A. And so on.

[0033] In some embodiments of this application, the shutdown driving method may further include:

[0034] The voltage change rate between the input and output terminals of the switching device is collected. If the voltage change rate is greater than a third threshold, the first or second time duration is reduced in the next switching device turn-off process; if the voltage change rate is less than or equal to the third threshold, the first or second time duration is increased in the next switching device turn-off process. In this embodiment, when it is determined that the voltage change rate is greater than the third threshold, i.e., the efficiency rating, it indicates that the switching device may be aging, causing parameter drift and resulting in voltage increase. Therefore, in the next switching device turn-off process, the first or second time duration is reduced to reduce the abnormal operating condition of voltage increase during turn-off control caused by switching device aging. When it is determined that the voltage change rate is less than or equal to the third threshold, the first or second time duration is increased in the next switching device turn-off process to reduce turn-off losses.

[0035] In this application, the first duration can be considered as the period during which the gate voltage of the switching device adaptively adjusts to or near the Miller voltage, and the second duration is the desaturation time of the switching device. Therefore, in order to improve the turn-off efficiency of the switching device and reduce turn-off losses, the first duration is generally controlled to be shorter than the second duration. Attached Figure Description

[0036] Figure 1This is a schematic diagram of the structure of the electrical equipment provided in the embodiments of this application;

[0037] Figure 2 Signal timing diagrams provided for embodiments of this application;

[0038] Figure 3 The circuit diagram provided for Embodiment 1;

[0039] Figure 4 This is a circuit diagram provided for Embodiment 2;

[0040] Figure 5 The circuit diagram provided for Embodiment 3;

[0041] Figure 6 The circuit diagram provided for Embodiment 4;

[0042] Figure 7 A flowchart for Example 4;

[0043] Figure 8 The circuit diagram provided for Example 5. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, a further detailed description of this application will be provided below in conjunction with the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction as described in this application are illustrative based on the accompanying drawings, but changes may be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.

[0045] It should be noted that specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below. The following descriptions are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0046] To facilitate understanding of the embodiments of this application, the relevant technologies involved in the embodiments of this application will be introduced first below.

[0047] One existing method for reducing turn-off losses in switching devices involves adjusting the value of the turn-off resistor within the drive circuit by acquiring the on-current of the target switching device and comparing it with a reference value. When the sampled on-current is small, a smaller turn-off resistor is selected, thus quickly turning off the switching device. When the sampled on-current is large, a larger turn-off resistor is selected, thereby reducing the impact of voltage spikes during rapid turn-off. This method uses different turn-off resistors under different load conditions to achieve a balance between voltage stress and turn-off losses. Essentially, it increases the turn-off speed by using a smaller turn-off resistor or a larger gate current, thereby reducing turn-off losses. However, its effect on reducing turn-off losses is limited. Once the turn-off resistor is reduced to a certain value, its impact on the turn-off speed diminishes, and further reductions in the turn-off resistor value cannot effectively reduce turn-off losses.

[0048] Another existing method to reduce the turn-off loss of switching devices is to reduce the drive voltage from a first level voltage to a second level voltage before the switching device is turned off, and maintain the second level voltage for a certain time (Tdesat) before turning off the switching device. This can improve the voltage slew rate (dv / dt) during the turn-off period. By detecting dv / dt during the turn-off period and adjusting the Tdesat time, dv / dt can be stabilized near a preset threshold, thereby optimizing the turn-off loss. However, since a fixed second level voltage is used as the desaturation voltage, the load range for achieving turn-off loss optimization is narrow, with high turn-off loss optimization only occurring near the rated load point. Furthermore, the circuitry required to implement functions such as detecting dv / dt and adjusting the Tdesat time is relatively complex.

[0049] Therefore, in order to address the problem that the optimization of turn-off losses of switching devices depends on the turn-off resistor, resulting in limited optimization effects, and to solve the problem that turn-off driving methods based on critical saturation turn-off have a narrow load range for turn-off loss optimization and are complex to implement, embodiments of this application provide a turn-off driving device, electrical equipment, and turn-off driving method. Before turning off the switching device, the gate voltage is adaptively adjusted to the critical saturation voltage, i.e., the first plateau level, using the Miller plateau effect, thereby reducing the turn-off losses of the switching device.

[0050] In this application, the Miller plateau effect is used to adaptively adjust the gate voltage from the conventional driving voltage to the critical saturation voltage, i.e., the first plateau level, without having to dynamically adjust the output level amplitude of the driving circuit as the turn-off current changes. The driving circuit implementation is relatively simple and can effectively optimize the turn-off loss.

[0051] Before introducing the embodiments of this application, let's first introduce some of the terms involved in the embodiments of this application by way of example:

[0052] 1. Miller Plateau Effect: The main cause of the Miller plateau effect is the parasitic capacitance within the switching device. In a metal-oxide-semiconductor field-effect transistor (MOSFET), the capacitance between the gate and drain (Cgd) causes a voltage drop during switching, resulting in the gate voltage remaining on a plateau for a period of time; this phenomenon is called the Miller plateau. In an insulated-gate bipolar transistor (IGBT), the Miller plateau is caused by the parasitic capacitance between the gate and collector (Cgc).

[0053] 2. High impedance: A high impedance state indicates that a node in a circuit has a relatively higher impedance than other points in the circuit.

[0054] 3. The process of turning off the switching device: The process of turning off the switching device refers to the process of the switching device switching from a high gate voltage (conducting state) to a low gate voltage (turning off state).

[0055] 4. Desaturation Process: The output characteristic curve of a voltage-type switching device can be divided into the cutoff region, the linear region, and the saturation region according to the switching state. When the switching device is normally turned on, it is in a voltage saturation state, and the voltage across it is a positive saturation voltage. When the current flowing through the switching device suddenly increases due to other factors, such as overcurrent or short circuit, the voltage across the switching device will also increase accordingly. When the current rises to the saturation current corresponding to the gate voltage of the switching device, the voltage will rise rapidly; this process is called the desaturation process.

[0056] The electrical equipment provided in this application embodiment can be an inverter, an uninterruptible power supply, or other equipment that realizes power conversion, and can be applied to power supply systems such as photovoltaic power generation systems and energy storage systems.

[0057] Reference Figure 1The electrical device provided in this application includes a switching device Q and a turn-off driving device, the turn-off driving device including a driving circuit. The switching device Q is used to turn on or off the connection between the electrical device and the load. Specifically, the switching device Q can be a MOSFET or an IGBT. A MOSFET includes a gate, a source, and a drain, while an IGBT includes a gate, a collector, and an emitter. In this application, the gates of the MOSFET and IGBT can be referred to as the control terminals of the switching device Q, the drain of the MOSFET and the collector of the IGBT can be referred to as the input terminals of the switching device Q, and the source of the MOSFET and the emitter of the IGBT can be referred to as the output terminals of the switching device Q. The driving circuit is connected to the control terminals and output terminals of the switching device Q, and the driving circuit is used to control the output terminal level to adjust the gate voltage V between the control terminals and the output terminals. G (t) is used to turn off the switching device Q. The output level is the same as the output level of the drive circuit. (Refer to...) Figure 2 Specifically, in the process of turning off a switching device: the drive circuit controls the output level to switch from high level to low level, and continues to output a low level for a first duration T1, so that the gate voltage V G (t) drops from high level. Afterwards, the drive circuit controls the output to be in a high-impedance state for a second duration T2, causing the gate voltage V to drop. G (t) Approaching the critical saturation voltage, i.e., the gate voltage V G (t) is at the first plateau level, and at this time it exhibits the gate voltage V G The voltage value at (t) is the same as the output level of the drive circuit. Therefore, it can be assumed that the output level of the drive circuit remains at the first plateau level for the second duration T2, and the gate voltage V G (t) The first plateau level is maintained for the third duration T3. The value of the first plateau level is between high and low. The start time of the second duration T2 is the end time of the first duration T1. The start time of the third duration T3 is equal to or later than the start time of the second duration T2. ​​The end time of the third duration T3 is the end time of the second duration T2. ​​Finally, the control output level switches from the first plateau level to a low level, so that the gate voltage V... G (t) Switches from the first platform level to a low level to turn off the switching device Q.

[0058] In this application, the high-impedance state of the drive circuit control output can be achieved by switching to a high-value drive resistor in the drive circuit. Alternatively, the high-impedance state of the drive circuit control output can be achieved by cutting off the current loop of the drive circuit. When the drive circuit control output is in a high-impedance state, the output level of the drive circuit is related to the gate voltage V of the switching device Q. G The values ​​of (t) are the same.

[0059] In this application, depending on the load rate of the electrical equipment, the gate voltage V during the switching process is adjusted. G The waveform of (t) can be in two states.

[0060] Reference Figure 2 In the first case, when the output level of the drive circuit switches from high to low and remains low for a first duration T1, the gate voltage V G (t) The voltage drops from high level to the Miller voltage, i.e., the second plateau level, and remains there for a fourth duration T4. The end time of the fourth duration T4 is the end time of the first duration T1. Afterwards, the drive circuit control output is in a high-impedance state for a second duration T2, resulting in the drive circuit output level remaining at the first plateau level for the second duration T2, and the gate voltage V... G (t) rises from the second platform level to the first platform level and remains at the first platform level for the third duration T3. At this time, the start time of the third duration T3 is later than the start time of the second duration T2, and the end time of the third duration T3 is the end time of the second duration T2.

[0061] In the above scenario, at the first moment t1 when the switching device is turned off, the output level of the drive circuit changes from high to low, and this low level lasts for a first duration T1. The purpose of this is to adjust the gate voltage V of the switching device Q. G (t) The voltage drops from the high level in the on-state to the Miller voltage, causing the switching device Q to begin desaturation. At the second moment t2 after the first duration T1 ends, the drive circuit control output is in a high-impedance state for the duration of the second duration T2. ​​The purpose of this high-impedance state is to increase the output impedance of the drive circuit, presenting a gate voltage V. G The voltage value of (t) is the same as the output level of the drive circuit. During this period, the current in the capacitor (Cgc) between the control terminal and the input terminal in the switching device Q changes from flowing to the output of the drive circuit to flowing to the capacitor (Cge) between the control terminal and the output terminal, thereby increasing the gate voltage V. G (t) The Miller voltage is slightly increased to bring it closer to the critical saturation voltage, achieving an effective desaturation process. At the third moment t3, after the second duration T2 ends, the drive circuit controls the output level to be low, causing the gate voltage V of the switching device Q to be low. G (t) transitions to a low level, thus turning off the switching device Q.

[0062] In the above situation, the first platform level and the second platform level can be adaptively adjusted, and the first platform level and the second platform level are positively correlated with the output power of the electrical equipment, that is, the greater the output power, the greater the values ​​of the first platform level and the second platform level.

[0063] Reference Figure 2 In the second scenario, when the electrical equipment is under light load (i.e., a low load condition), and the drive circuit switches its control output level from high to low and maintains a low level for a first duration T1, the gate voltage V... G (t) The gate voltage V continuously decreases from a high level and does not drop to the Miller voltage, i.e., the second plateau level. During the first duration T1, the gate voltage V... G (t) Before the voltage drops to the Miller voltage, the drive circuit control output is in a high-impedance state for a second duration T2, indicating that the output level of the drive circuit remains at the first plateau level for the second duration T2, and the gate voltage V G (t) remains at the first platform level for the third duration T3. At this time, the start time of the third duration T3 is equal to the start time of the second duration T2, and the end time of the third duration T3 is equal to the end time of the second duration T2.

[0064] In the above scenario, at the first moment t1 when the switching device is turned off, the output level of the drive circuit changes from high to low, and this low level lasts for a first duration T1. The purpose of this is to adjust the gate voltage V of the switching device Q. G (t) The high level during the on-state drops, causing the switching device Q to begin desaturation. At the second moment t2 after the first duration T1 ends, the drive circuit control output is in a high-impedance state for the duration of the second duration T2. ​​The purpose of this high-impedance state is to increase the output impedance of the drive circuit, resulting in a gate voltage V. G The voltage value of (t) is the same as the output level of the drive circuit. During this period, the current in the capacitor (Cgc) between the control terminal and the input terminal in the switching device Q changes from flowing to the output of the drive circuit to flowing to the capacitor (Cge) between the control terminal and the output terminal, thereby increasing the gate voltage V. G (t) Approaching the critical saturation voltage, an effective desaturation process is achieved. At the third moment t3, after the end of the second duration T2, the drive circuit controls the output level to be low, causing the gate voltage V of the switching device Q to be low. G (t) transitions to a low level, thus turning off the switching device Q.

[0065] In the above situation, the first platform level can be adaptively adjusted, and the first platform level is positively correlated with the output power of the electrical equipment, that is, the greater the output power, the greater the value of the first platform level.

[0066] In this application, the driving circuit utilizes the Miller plateau effect of the switching device Q, first by outputting a low level for a first duration T1 to reduce the gate voltage V of the switching device Q. G (t) Reaching or approaching the Miller plateau, and then adaptively achieving the gate voltage V of the switching device Q by controlling the output to remain in a high-impedance state for a second duration T2. G(t) The voltage is adjusted from high level to critical saturation voltage without dynamically adjusting the output of the drive circuit as the turn-off current changes. The drive circuit is relatively simple to implement and can effectively reduce turn-off losses.

[0067] In this application, the amplitude of the low-level signal in the turn-off drive signal is typically less than the turn-off threshold voltage of the switching device Q, so as to ensure that the switching device Q is turned off under the control of the turn-off drive signal.

[0068] In this application, the first duration T1 can be considered as the period during which the gate voltage of the switching device Q adaptively adjusts to or near the Miller voltage, and the second duration T2 is the desaturation time of the switching device Q. Therefore, in order to improve the turn-off efficiency of the switching device Q and reduce turn-off losses, the first duration T1 is generally shorter than the second duration T2. ​​In specific implementations, the first duration T1 and the second duration T2 can be set to fixed values, or they can be dynamically adjusted values.

[0069] The implementation method of controlling the output level of the driving circuit provided in this application will be described in detail below through specific embodiments.

[0070] Example 1:

[0071] Reference Figure 3 The turn-off drive device includes a controller and a drive circuit. The controller is connected to the drive circuit, which is used to connect to the control terminal and output terminal of the switching device. The controller outputs a control signal to the drive circuit, and the drive circuit controls the output terminal level according to the control signal to adjust the gate voltage, thereby turning off the switching device Q.

[0072] Specifically, the drive circuit controls the output level to switch from high to low according to the control signal and maintains the low level for a first duration T1, so that the gate voltage V G (t) drops from high level. Afterwards, the drive circuit controls the output to be in a high-impedance state for a second duration T2, causing the gate voltage V to drop. G (t) Approaching the critical saturation voltage, i.e., the gate voltage V G (t) is at the first plateau level, and at this time it exhibits the gate voltage V G The voltage value at (t) is the same as the output level of the drive circuit. It can be assumed that at this time, the output level of the drive circuit remains at the first plateau level for the second duration T2, and the gate voltage V... G (t) The first plateau level is maintained for the third duration T3. Finally, the drive circuit controls the output level to switch from the first plateau level to a low level, so that the gate voltage V G (t) Switches from the first platform level to a low level to turn off the switching device Q.

[0073] Specifically, the controller can output control signals to the drive circuit in several ways. For example, the controller can output two control signals to the drive circuit: a first control signal and a second control signal. When both the first and second control signals are high, the drive circuit's output level is high; when both are low, the output level is low; and when both are high, the output is in a high-impedance state. Alternatively, the controller can output three control signals to the drive circuit: a first control signal, a second control signal, and a third control signal. When the first control signal is high, the output level is high; when the second control signal is high, the output is low; and when the third control signal is high, the output is in a high-impedance state.

[0074] In this embodiment, the controller can control the output level of the drive circuit to remain low for a first duration T1 and the output to be in a high impedance state for a second duration T2 by adjusting the control signal to maintain different levels for different durations. Furthermore, both the first duration T1 and the second duration T2 can be fixed values, or, after setting initial values ​​for the first duration T1 and the second duration T2, the first duration T1 and the second duration T2 can be adjusted in real time based on detected system parameters of the power converter, such as inductor current.

[0075] Example 2:

[0076] Reference Figure 4 Based on Embodiment 1, the shutdown drive device may further include: a first sampling circuit and a first judgment circuit. The first sampling circuit is used to sample the current Ic or other equivalent signal at the output terminal of the switching device Q during the first time period T1 and the second time period T2, and then outputs the first sampling signal to the first judgment circuit. The first judgment circuit is used to determine whether the switching device Q has an abnormal operating condition due to excessive current caused by factors such as load short circuit or device aging, based on the sampled current Ic.

[0077] Specifically, when the first judgment circuit determines that the current Ic is greater than the first threshold, i.e., the rated current value, it indicates an abnormal operating condition of excessive current. In the next process of turning off the switching device, it outputs a first enable signal to the controller. Upon receiving the first enable signal, the controller directly outputs a normal turn-off signal, i.e., a constant low-level signal, to the drive circuit. Upon receiving the turn-off signal, the drive circuit directly controls the output level to switch from high to low, thereby reducing the gate voltage V. G(t) The voltage level drops from high to low, turning off the switching device Q. When the controller does not receive the first enable signal, it outputs the control signal mentioned in Embodiment 1 to the drive circuit. Upon receiving the control signal, the drive circuit controls the output level to switch from high to low and maintains a low level for a first duration T1, thereby reducing the gate voltage V. G (t) drops from high level. Afterwards, the drive circuit controls the output to be in a high-impedance state for a second duration T2, causing the gate voltage V to drop. G (t) Approaching the critical saturation voltage, i.e., the gate voltage V G (t) is at the first plateau level, and at this time it exhibits the gate voltage V G The voltage value at (t) is the same as the output level of the drive circuit. It can be assumed that at this time, the output level of the drive circuit remains at the first plateau level for the second duration T2, and the gate voltage V... G (t) The first plateau level is maintained for the third duration T3. Finally, the drive circuit controls the output level to switch from the first plateau level to a low level, so that the gate voltage V G (t) Switches from the first platform level to a low level to turn off the switching device Q.

[0078] In this embodiment, the signals output by the controller to the drive circuit are of two types. One is a normal turn-off signal, i.e., a constant low level, when the current is too large, to ensure that the drive circuit can control the switching device Q to turn off normally. The other is the control signal provided in this application, which can reduce the turn-off loss under normal operating conditions of the switching device Q.

[0079] In this embodiment, the first duration T1, the second duration T2, and the first threshold can all be fixed values.

[0080] Example 3:

[0081] Reference Figure 5 Based on Embodiment 1 or Embodiment 2, the turn-off driving device may further include: a second sampling circuit and a second judgment circuit. The second sampling circuit is used to acquire the voltage Vce between the input and output terminals of the switching device Q, and then output a second sampling signal to the second judgment circuit. The second judgment circuit is used to determine, based on the sampled voltage Vce, whether there is an abnormal operating condition due to excessive voltage caused by factors such as device aging when the gate voltage of the switching device Q is increased during the second time period T2, i.e., when the control output of the driving circuit is in a high-impedance state.

[0082] Specifically, when the second judgment circuit determines that the voltage Vce is greater than the second threshold, i.e., the rated voltage, it indicates an abnormal operating condition of excessive voltage and outputs a second enable signal to the drive circuit. Upon receiving the second enable signal, the drive circuit stops controlling the output to maintain a high impedance state and directly controls the output level to switch to a low level. When the drive circuit does not receive the second enable signal, it continues to control the output to maintain a high impedance state.

[0083] In this embodiment, when an abnormal operating condition is detected due to excessive voltage, the drive circuit directly pulls the output level down to a low level, which can prevent damage to the switching device Q and increase turn-off losses. When the voltage of the switching device Q is detected to be under normal operating conditions, the drive circuit controls the output to output in the manner provided in this application, which can turn off the switching device Q with less turn-off loss.

[0084] In this embodiment, the first duration T1, the second duration T2, the first threshold, and the second threshold can all be fixed values.

[0085] Example 4:

[0086] Reference Figure 6 Based on Embodiment 3, the second judgment circuit is also used to output a second enable signal to the controller so that the controller can dynamically adjust the first threshold, i.e. the current rating, during the process of turning off the next switching device according to the second enable signal.

[0087] Reference Figure 7 The controller adjusts the first threshold as follows:

[0088] S1. Set the first threshold to the initial value, which is the maximum value of the first threshold.

[0089] S2. During the current process of turning off the switching device, determine whether the current Ic is greater than the first threshold, i.e., whether the first enable signal has been received. If yes, proceed to step S3; otherwise, proceed to step S4.

[0090] S3. In the next process of turning off the switching device, keep the first threshold unchanged.

[0091] S4. Output a control signal to the drive circuit so that the drive circuit outputs a control signal in accordance with the manner provided in this application.

[0092] S5. During the current process of turning off the switching device, determine whether a second enable signal has been received. If yes, proceed to step S6; otherwise, proceed to step S7.

[0093] S6. In the next process of turning off the switching device, the first threshold is reduced by ΔI.

[0094] S7. Determine whether the second enable signal was not received by any of the consecutive turn-off switching devices in the previous process where the current Ic was less than the first threshold (i.e., no first enable signal was received). If yes, proceed to step S8; otherwise, proceed to step S3.

[0095] S8. In the next process of turning off the switching device, the first threshold is increased by ΔI.

[0096] In this embodiment, the controller adjusts the first threshold based on the second enable signal to reduce the risk of the drive circuit terminating its output high impedance state due to abnormal voltage rise caused by device aging. For example, if the initial value of the first threshold is set to 100A, and the output level is controlled to turn off the switching device Q using the method provided in this application, no abnormality occurs, i.e., neither the first nor the second enable signal is received. As the switching device Q is used, it ages, causing parameter drift. During a certain process of turning off the switching device, the first enable signal may not be received, but the second enable signal is received. This indicates that using the current first threshold for judgment would detect an abnormal voltage rise and terminate the drive circuit's control output high impedance state. Therefore, the first threshold needs to be reduced, for example, to 90A. After reducing the first threshold, if multiple consecutive processes of turning off the switching device do not receive either the first or second enable signal, the first threshold can be appropriately increased, for example, to 95A. And so on.

[0097] Example 5:

[0098] Reference Figure 8 Based on Embodiments 1 to 4, the turn-off drive device may further include: a third sampling circuit. The third sampling circuit is used to acquire the voltage change rate (dv) between the input and output terminals of the switching device Q. ce / dt), and then outputs a third sampling signal to the controller. The controller is used to determine the aging status of the device based on the sampled voltage change rate and dynamically adjust the first duration T1 and the second duration T2.

[0099] Specifically, when the controller determines that the voltage change rate is greater than the third threshold, i.e., the rated efficiency, it indicates that the switching device Q may be aging, causing parameter drift and resulting in an increase in voltage Vce. Therefore, in the next process of turning off the switching device, the first duration T1 or the second duration T2 is reduced by Δt to mitigate the abnormal voltage increase during the turn-off control caused by the aging of the switching device Q. When the controller determines that the voltage change rate is less than or equal to the third threshold, the first duration T1 or the second duration T2 is increased by Δt in the next process of turning off the switching device to reduce turn-off losses. The minimum adjustment step size of the first duration T1 is generally smaller than the minimum adjustment step size of the second duration T2, and both the first duration T1 and the second duration T2 need to be limited by a maximum upper limit value.

[0100] Based on the same inventive concept, embodiments of this application also provide a shutdown driving method, including:

[0101] First, the control output level switches from high level to low level and continues to output low level for a first duration, so that the gate voltage between the control terminal and the output terminal of the switching device drops from high level;

[0102] Subsequently, the control output level remains at the first plateau level for the second duration, and the control gate voltage remains at the first plateau level for the third duration. The value of the first plateau level is between high and low levels. The start time of the second duration is the end time of the first duration, the start time of the third duration is equal to or later than the start time of the second duration, and the end time of the third duration is the end time of the second duration.

[0103] Finally, the control output level is switched from the first platform level to a low level, so that the gate voltage is switched from the first platform level to a low level, thereby turning off the switching device.

[0104] In this application, depending on the load rate of the electrical equipment, the waveform of the gate voltage will be in two different states during the process of turning off the switching device.

[0105] In the first scenario, when the control output level switches from high to low and remains low for a first duration, the gate voltage drops from high to the Miller voltage (the second plateau level) and remains low for a fourth duration. The end of the fourth duration coincides with the end of the first duration. Afterward, the control output is in a high-impedance state for a second duration, resulting in the output level remaining at the first plateau level for the second duration. Simultaneously, the gate voltage rises from the second plateau level to the first plateau level and remains at the first plateau level for a third duration. The start of the third duration is later than the start of the second duration, and the end of the third duration coincides with the end of the second duration.

[0106] In the above scenario, at the initial moment of switching off the device, the output level changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage from the high level (in the on-state) to the Miller voltage, causing the device to begin desaturation. At the second moment after the first time, the control output enters a high-impedance state for a duration of two times. This increases the output impedance, making the gate voltage equal to the output level. During this period, the current in the capacitor between the control and input terminals changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, slightly increasing the gate voltage from the Miller voltage and bringing it closer to the critical saturation voltage, thus achieving an effective desaturation process. At the third moment after the second time, the control output level returns to low, causing the gate voltage of the device to drop, effectively turning off the device.

[0107] In the above situation, the first platform level and the second platform level can be adaptively adjusted, and the first platform level and the second platform level are positively correlated with the output power of the electrical equipment, that is, the greater the output power, the greater the values ​​of the first platform level and the second platform level.

[0108] In the second scenario, under light load conditions (i.e., when the electrical equipment is under low load), as the control output level switches from high to low and remains low for a first duration, the gate voltage continuously decreases from high but does not reach the Miller voltage (the second plateau level). Before the gate voltage reaches the Miller voltage within the first duration, the control output is in a high-impedance state for a second duration. This results in the output level remaining at the first plateau level for the second duration, and the gate voltage remaining at the first plateau level for a third duration. In this case, the start time of the third duration is equal to the start time of the second duration, and the end time of the third duration is equal to the end time of the second duration.

[0109] In the above scenario, at the initial moment of switching off the device, the output level changes from high to low for a duration of one time. This low level is intended to reduce the gate voltage of the switching device from its high state (on-hand) to allow desaturation. At the second moment after the first time, the control output enters a high-impedance state for a duration of two times. This increases the output impedance, ensuring the gate voltage matches the output level. During this period, the current in the capacitor between the control and input terminals changes from flowing to the output of the drive circuit to flowing to the capacitor between the control and output terminals, bringing the gate voltage close to the critical saturation voltage and achieving an effective desaturation process. At the third moment after the second time, the control output level returns to low, causing the gate voltage of the switching device to drop, thus turning off the device.

[0110] In the above situation, the first platform level can be adaptively adjusted, and the first platform level is positively correlated with the output power of the electrical equipment, that is, the greater the output power, the greater the value of the first platform level.

[0111] In this application, the Miller plateau effect of the switching device is utilized. First, the gate of the switching device reaches or approaches the Miller plateau by maintaining a low output level for a first duration. Then, by controlling the output to be in a high impedance state for a second duration, the gate voltage of the switching device is adaptively adjusted from a high level to the critical saturation voltage without having to dynamically adjust the output of the drive circuit as the turn-off current changes. The drive circuit is relatively simple to implement and can effectively reduce turn-off losses.

[0112] In some embodiments of this application, the shutdown driving method may further include: sampling the current at the output terminal of the switching device for a first duration and a second duration. If the sampled current is greater than a first threshold, in the next shutdown process of the switching device, the output terminal level is controlled to switch from a high level to a low level, so that the gate voltage drops from a high level to a low level. If the current is less than or equal to the first threshold, in the next shutdown process of the switching device, the output terminal level is controlled to switch from a high level to a low level and continuously output at a low level for a first duration, the output terminal level is controlled to remain at a first plateau level for a second duration, and the output terminal level is controlled to switch from the first plateau level to a low level. In this embodiment, based on the sampled current before shutdown, it is determined that the switching device is in an abnormal operating condition due to excessive current caused by factors such as load short circuit or device aging. In the next shutdown process, a conventional shutdown signal, i.e., a constant low-level signal, is used to directly switch the output level to a low level to shut down the switching device, thus ensuring normal shutdown of the control switching device. When it is determined that the switching device is in a normal operating condition based on the sampled current before shutdown, the control output level method provided in this application is used to shut down the switching device in the next shutdown process, which can reduce shutdown losses.

[0113] In some embodiments of this application, the shutdown driving method may further include: acquiring the voltage between the input and output terminals of the switching device. During a first duration and a second duration, if the voltage exceeds a second threshold, the output terminal level is controlled to switch to a low level. In this embodiment, when an abnormal operating condition is determined to be due to excessive voltage, directly pulling the output terminal level down to a low level can prevent damage to the switching device and increase shutdown losses; when the voltage of the switching device is determined to be under normal operating conditions, using the method of controlling the output terminal level provided in this application to control the shutdown of the switching device can reduce shutdown losses.

[0114] In some embodiments of this application, the shutdown driving method may further include: if the current is greater than a first threshold, controlling the first threshold to remain unchanged in the next shutdown process of the switching device; if the current is less than the first threshold and the voltage is greater than a second threshold, decreasing the first threshold in the next shutdown process of the switching device; if the current is less than the first threshold and the voltage is less than or equal to the second threshold, increasing the first threshold in the next shutdown process of the switching device if, in the previous multiple shutdown processes, the current is less than the first threshold and the voltage is less than or equal to the second threshold; the maximum value of the first threshold is the initial value. In this embodiment, dynamically adjusting the first threshold based on the sampled voltage and current can reduce the situation where the control output high impedance state is terminated due to abnormal voltage rise caused by device aging. For example, setting the initial value of the first threshold to 100A and using the method provided in this application to control the output level to shut down the switching device, no abnormality occurred. As switching devices age, parameter drift occurs. During a switching process where the current sampled is normal, but the sampled voltage is abnormal, it indicates that using the current first threshold will detect the abnormal voltage rise and terminate the control output in a high-impedance state. Therefore, the first threshold needs to be reduced, for example, to 90A. After reducing the first threshold, if the current and voltage sampled during multiple consecutive switching processes are normal, the first threshold can be appropriately increased, for example, to 95A. And so on.

[0115] In some embodiments of this application, the shutdown driving method may further include: acquiring the voltage change rate between the input and output terminals of the switching device. If the voltage change rate is greater than a third threshold, in the next shutdown process of the switching device, the first duration or the second duration is reduced; if the voltage change rate is less than or equal to the third threshold, in the next shutdown process of the switching device, the first duration or the second duration is increased. In this embodiment, when it is determined that the voltage change rate is greater than the third threshold, i.e., the efficiency rating, it indicates that the switching device may be aging, causing parameter drift and resulting in voltage increase. Therefore, in the next shutdown process of the switching device, the first duration or the second duration is reduced to reduce the abnormal operating condition of voltage increase during shutdown control caused by switching device aging. When it is determined that the voltage change rate is less than or equal to the third threshold, in the next shutdown process of the switching device, the first duration or the second duration is increased to reduce shutdown losses.

[0116] In this application, the first duration can be considered as the period during which the gate voltage of the switching device adaptively adjusts to or near the Miller voltage, and the second duration is the desaturation time of the switching device. Therefore, in order to improve the turn-off efficiency of the switching device and reduce turn-off losses, the first duration is generally controlled to be shorter than the second duration.

[0117] The turn-off driving device, electrical equipment, and turn-off driving method provided in this application utilize the Miller plateau effect of the switching device to control the output terminal level to switch from a high level to a low level, and maintain the low level for a first duration, so that the gate voltage drops from a high level to or near the Miller plateau. Then, the control output is in a high-impedance state for a second duration, causing the gate voltage to approach the critical saturation voltage, i.e., the gate voltage is at the first plateau level, and at this time, the gate voltage value is the same as the output terminal level of the driving circuit. It can be considered that at this time, the output terminal level of the driving circuit remains at the first plateau level for the second duration, and the gate voltage remains at the first plateau level for the third duration. Finally, the control output terminal level switches from the first plateau level to a low level, causing the gate voltage to switch from the first plateau level to a low level, thereby turning off the switching device. The turn-off driving method of the switching device provided in this application adaptively adjusts the gate voltage of the switching device from a high level to the critical saturation voltage, which can effectively reduce turn-off losses; the gate voltage is adaptively adjusted to the critical saturation voltage without dynamically adjusting the output of the driving circuit according to changes in the turn-off current, and its driving circuit implementation is relatively simple.

[0118] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A shutdown drive device, characterized in that, Including the drive circuit; Therefore, the driving circuit is used to connect to the control terminal and the output terminal of the switching device. The driving circuit is used to control the output terminal level to adjust the gate voltage between the control terminal and the output terminal to turn off the switching device. The driving circuit is specifically used for: The output level is controlled to switch from high level to low level, and the low level is continuously output for a first duration, so that the gate voltage drops from the high level; The output voltage is controlled to remain at the first plateau level for a second duration, and the gate voltage is controlled to remain at the first plateau level for a third duration, wherein the value of the first plateau level is between the high level and the low level; the start time of the second duration is the end time of the first duration, the start time of the third duration is equal to or later than the start time of the second duration, and the end time of the third duration is the end time of the second duration; The output level is controlled to switch from the first platform level to the low level, so that the gate voltage switches from the first platform level to the low level.

2. The shutdown drive device as described in claim 1, characterized in that, The driving circuit is specifically used for: The output level is controlled to switch from the high level to the low level, and the low level is continuously output for the first duration, so that the gate voltage drops from the high level to the second plateau level and continues for a fourth duration; the end time of the fourth duration is the end time of the first duration; The output level is controlled to remain at the first platform level for the second duration, and the gate voltage is controlled to rise from the second platform level to the first platform level and remain at the first platform level for the third duration; the start time of the third duration is later than the start time of the second duration.

3. The shutdown drive device as described in claim 1 or 2, characterized in that, Also includes: Controller; The controller is used to output control signals to the drive circuit; The driving circuit is used to: control the output terminal level to switch from the high level to the low level according to the control signal and continuously output the low level for the first duration, control the output terminal level to remain at the first platform level for the second duration, and control the output terminal level to switch from the first platform level to the low level.

4. The shutdown drive device as described in claim 3, characterized in that, Also includes: The first sampling circuit and the first judgment circuit; The first sampling circuit is used to: sample the current at the output terminal of the switching device during the first duration and the second duration; The first determination circuit is used to: if the current is greater than the first threshold, output a first enable signal to the controller in the next process of turning off the switching device; The controller is configured to: if it receives the first enable signal, output a shutdown signal to the drive circuit; or if it does not receive the first enable signal, output the control signal to the drive circuit. The driving circuit is configured to: control the output terminal level to switch from the high level to the low level according to the control signal and continuously output the low level for the first duration; control the output terminal level to remain at the first platform level for the second duration; and control the output terminal level to switch from the first platform level to the low level; or, control the output terminal level to switch from the high level to the low level according to the turn-off signal, so that the gate voltage drops from the high level to the low level.

5. The shutdown drive device as described in claim 4, characterized in that, Also includes: Second sampling circuit and second judgment circuit; The second sampling circuit is used to: acquire the voltage between the input and output terminals of the switching device; The second judgment circuit is used to: if the voltage is greater than the second threshold during the first duration and the second duration, output a second enable signal to the driving circuit; The driving circuit is used to: if the second enable signal is received, control the output terminal level to switch to the low level.

6. The shutdown drive device as described in claim 5, characterized in that, The second judgment circuit is further configured to: if the voltage is greater than the second threshold, output the second enable signal to the controller; The controller is configured to: if the first enable signal is received, maintain the first threshold unchanged in the next process of turning off the switching device; if the first enable signal is not received but the second enable signal is received, decrease the first threshold in the next process of turning off the switching device; if neither the first enable signal nor the second enable signal is received, in the previous multiple consecutive processes of turning off the switching device, if neither the first enable signal nor the second enable signal is received, increase the first threshold in the next process of turning off the switching device; the maximum value of the first threshold is the initial value.

7. The shutdown drive device according to any one of claims 3-6, characterized in that, Also includes: Third sampling circuit; The third sampling circuit is used to: collect the voltage change rate between the input and output terminals of the switching device; The controller is configured to: if the voltage change rate is greater than a third threshold, decrease the first duration or the second duration in the next process of turning off the switching device; if the voltage change rate is less than or equal to the third threshold, increase the first duration or the second duration in the next process of turning off the switching device.

8. The shutdown drive device according to any one of claims 1-7, characterized in that, The first duration is shorter than the second duration.

9. An electrical device, characterized in that, The electrical equipment includes a shutdown drive device as described in any one of claims 1-8 and the switching device, the switching device being used to connect or disconnect the electrical equipment from the load.

10. The electrical equipment as claimed in claim 9, characterized in that, One or both of the first platform level and the second platform level are positively correlated with the output power of the electrical equipment.

11. A shutdown driving method, characterized in that, include: The control output level switches from high level to low level and continues to output the low level for a first duration, so that the gate voltage between the control terminal and the output terminal of the switching device drops from the high level; The output voltage is controlled to remain at the first plateau level for a second duration, and the gate voltage is controlled to remain at the first plateau level for a third duration, wherein the value of the first plateau level is between the high level and the low level; the start time of the second duration is the end time of the first duration, the start time of the third duration is equal to or later than the start time of the second duration, and the end time of the third duration is the end time of the second duration; The output level is controlled to switch from the first platform level to the low level, so that the gate voltage switches from the first platform level to the low level, thereby turning off the switching device.

12. The shutdown driving method as described in claim 11, characterized in that, Specifically, it includes: The output level is controlled to switch from the high level to the low level, and the low level is continuously output for the first duration, so that the gate voltage drops from the high level to the second plateau level and continues for a fourth duration; the end time of the fourth duration is the end time of the first duration; The output level is controlled to remain at the first platform level for the second duration, and the gate voltage is controlled to rise from the second platform level to the first platform level and remain at the first platform level for the third duration; the start time of the third duration is later than the start time of the second duration.

13. The shutdown driving method as described in claim 11 or 12, characterized in that, Also includes: Sample the current at the output terminal of the switching device during the first and second time durations; If the current is greater than the first threshold, in the next process of turning off the switching device, the output level is controlled to switch from the high level to the low level, so that the gate voltage drops from the high level to the low level. If the current is less than or equal to the first threshold, in the next process of turning off the switching device, the output terminal level is controlled to switch from the high level to the low level and the low level is continuously output for the first duration. The output terminal level is controlled to remain at the first platform level for the second duration, and the output terminal level is controlled to switch from the first platform level to the low level.

14. The shutdown driving method as described in claim 13, characterized in that, Also includes: The voltage between the input and output terminals of the switching device is collected; If the voltage is greater than the second threshold during the first and second durations, the output level is controlled to switch to the low level.

15. The shutdown driving method as described in claim 14, characterized in that, Also includes: If the current is greater than the first threshold, in the next process of turning off the switching device, the first threshold is controlled to remain unchanged; If the current is less than the first threshold and the voltage is greater than the second threshold, the first threshold is reduced in the next process of turning off the switching device. If the current is less than the first threshold and the voltage is less than or equal to the second threshold, in the previous multiple consecutive processes of turning off the switching device, if the current is less than the first threshold and the voltage is less than or equal to the second threshold, in the next process of turning off the switching device, the first threshold is increased; the maximum value of the first threshold is the initial value.

16. The shutdown driving method according to any one of claims 11-15, characterized in that, Also includes: The voltage change rate between the input and output terminals of the switching device is collected; If the voltage change rate is greater than the third threshold, in the next process of turning off the switching device, the first duration or the second duration is reduced; if the voltage change rate is less than or equal to the third threshold, in the next process of turning off the switching device, the first duration or the second duration is increased.

17. The shutdown driving method according to any one of claims 11-16, characterized in that, Also includes: The first duration is controlled to be less than the second duration.

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