Power conversion equipment, control method thereof and switch driving chip

Abstract

The invention provides a power conversion device and a control method thereof, and a switch driving chip, and relates to the technical field of switch control, the power conversion device comprises a controller, a first switch tube and a second switch tube, the controller provides a first driving current for a grid electrode of the first switch tube when a turn-off moment of the first switch tube arrives, and the controller provides a second driving current for a grid electrode of the second switch tube when the turn-off moment of the second switch tube arrives; when the voltage difference of the first switch tube is greater than or equal to a first threshold value, a second driving current is provided for the grid of the first switch tube so as to control the voltage of the grid of the first switch tube to rise; and when the voltage difference of the first switching tube is greater than or equal to a second threshold value, or the time duration for providing the second driving current is greater than or equal to a time threshold value, providing a third driving current for the grid electrode of the first switching tube to control the voltage of the grid electrode of the first switching tube to drop to turn off. According to the invention, the generation of voltage stress and EMI can be reduced, the turn-off speed of the first switching tube is improved, the turn-off loss is reduced, and the applicability is high.

Description

Technical Field

[0001] The present application relates to the field of switch control technology, and in particular to a power conversion device and a control method thereof, and a switch driving chip. Background Art

[0002] A switch tube refers to a power device with good on and off characteristics under certain conditions. The power conversion device can turn on and off the switch tube by applying a control signal to the control end (such as the gate) of the switch tube. During the process of turning off the switch tube, the channel current of the switch tube and the channel voltage at both ends of the switch tube will overlap, thereby generating turn-off losses.

[0003] Generally, in order to reduce the turn-off loss of the switch tube, the power conversion device can speed up the turn-off speed of the switch tube to shorten the overlapping interval of the channel current and channel voltage of the switch tube, thereby reducing the turn-off loss of the switch tube. However, when the switch tube is turned off quickly, the channel voltage at both ends of the switch tube changes rapidly, which will cause a large voltage stress at both ends of the switch tube. At the same time, the generated clutter signal will be enhanced, causing serious electromagnetic interference (EMI) and voltage stress problems. Therefore, how to reduce the voltage stress and EMI generated by the switch tube while reducing the turn-off loss of the switch tube is a technical problem that technicians in this field urgently need to solve. Summary of the invention

[0004] The present application provides a power conversion device and a control method thereof, and a switch driver chip. The power conversion device can reduce voltage stress and EMI generation while increasing the turn-off speed of the first switch tube, thereby reducing turn-off losses and having strong applicability.

[0005] In a first aspect, the present application provides a power conversion device, which includes a controller, a first switch tube and a second switch tube connected in series; the gate of the first switch tube is connected to the controller, the first electrode of the first switch tube is connected to the second switch tube, and the second electrode of the first switch tube is grounded or connected to a bus, and the controller is used to: when the shutdown moment of the first switch tube arrives, provide a first drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to a first threshold, provide a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase; when the second drive current is provided to the gate of the first switch tube, when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, or when the time length of providing the second drive current to the gate of the first switch tube is greater than or equal to the time threshold, provide a third drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease until the first switch tube is turned off. In the present application, when the turn-off time of the first switch tube arrives, the power conversion device controls the gate voltage of the first switch tube to decrease through the controller, and controls the gate voltage of the first switch tube to increase when the voltage difference across the first switch tube reaches the first threshold, which can effectively reduce the generation of voltage stress and EMI. Further, when the voltage difference across the first switch tube of the power conversion device reaches the second threshold, or when the time length of the controller providing the second drive current, that is, the time length of the gate voltage increase of the first switch tube reaches the time threshold, the gate voltage of the first switch tube is controlled by the controller to change from increasing to decreasing until the first switch tube is completely turned off, which can reduce the generation of voltage stress and EMI while increasing the turn-off speed of the first switch tube, thereby reducing the turn-off loss.

[0006] In combination with the first aspect, in a first possible implementation, the controller is used to: obtain the gate voltage of the first switch tube when providing the first drive current to the gate of the first switch tube, and provide the fourth drive current to the gate of the first switch tube when the gate voltage of the first switch tube is less than or equal to the third threshold value, so as to control the gate voltage of the first switch tube to decrease at a rate less than the first rate, wherein the first rate is the rate of decrease of the gate voltage of the first switch tube when the first drive current is provided to the gate of the first switch tube. In the present application, after the power conversion device provides the first drive current to the gate of the first switch tube, the gate voltage of the first switch tube can be obtained by the controller, and when the gate voltage of the first switch tube is less than or equal to the third threshold value, the rate of decrease of the gate voltage of the first switch tube can be controlled to decrease by the controller, thereby further improving the turn-off speed of the first switch tube while reducing the voltage stress and EMI generation, and effectively reducing the turn-off loss.

[0007] In combination with the first aspect to any one of the first possible implementations of the first aspect, in a second possible implementation, the controller is used to: obtain the current magnitude of the first drive current and the current magnitude of the third drive current based on the gate drive current used to control the first switch tube to be turned off at the target turn-off speed. In the present application, the controller can obtain the current magnitudes of the first drive current and the third drive current based on the gate drive current corresponding to the target turn-off speed. Furthermore, when the controller drives the first switch tube based on the first drive current or the third drive current, the gate voltage of the first switch tube can be rapidly reduced, thereby further improving the turn-off speed of the first switch tube and effectively reducing the turn-off loss.

[0008] In combination with any one of the first aspect to the second possible implementation of the first aspect, in a third possible implementation, the controller is used to: after providing the first drive current to the gate of the first switch tube, detect the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, and obtain the magnitude of the second drive current based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. In the present application, when the controller drives the first switch tube based on the second drive current, the gate voltage of the first switch tube can be increased to reduce voltage stress and EMI generation. Among them, the controller obtains the current magnitude of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, which is easy to implement and has high accuracy.

[0009] In combination with any one of the first aspect to the second possible implementation of the first aspect, in a fourth possible implementation, the controller is used to: after providing the first drive current to the gate of the first switch tube, detect the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, and obtain the magnitude of the second drive current based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the working voltage of the bus. In the present application, when the controller drives the first switch tube based on the second drive current, the gate voltage of the first switch tube can be increased to reduce voltage stress and EMI generation. wherein, the controller obtains the current magnitude of the second drive current based on the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, which is easy to implement and has high accuracy.

[0010] In combination with any one of the first aspect to the second possible implementation of the first aspect, in a fifth possible implementation, the controller is used to: when providing the second drive current to the gate of the first switch tube, adjust the current size of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. In the present application, after providing the second drive current to the first switch tube, the controller can adjust the current size of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, thereby effectively reducing voltage stress and EMI generation, which is easy to implement and can be adjusted in real time.

[0011] In combination with any one of the first aspect to the second possible implementation of the first aspect, in a sixth possible implementation, the controller is used to: when providing the second drive current to the gate of the first switch tube, adjust the magnitude of the second drive current based on the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus. In the present application, after providing the second drive current to the first switch tube, the controller can adjust the current magnitude of the second drive current based on the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, thereby effectively reducing voltage stress and EMI generation, which is easy to implement and can be adjusted in real time.

[0012] In combination with any one of the first aspect to the sixth possible implementation of the first aspect, in a seventh possible implementation, the controller is used to: after providing the first drive current to the gate of the first switch tube, detect the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, and obtain the time threshold based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. In the present application, the controller can determine the value of the above-mentioned time threshold based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube after providing the first drive current to the first switch tube, which is easy to implement and has high accuracy.

[0013] In combination with any one of the first aspect to the sixth possible implementation of the first aspect, in an eighth possible implementation, the controller is used to: after providing the first drive current to the gate of the first switch tube, detect the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, and obtain the time threshold based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus. In the present application, the controller can determine the value of the above-mentioned time threshold based on the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference after providing the first drive current to the first switch tube, which is easy to implement and has high accuracy.

[0014] In combination with any one of the first aspect to the eighth possible implementation manner of the first aspect, in a ninth possible implementation manner, the controller is used to: when the turn-on moment of the first switch tube arrives, provide a fifth drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, provide a sixth drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be less than a first increase rate, and the first increase rate is the increase rate of the gate voltage of the first switch tube when the fifth drive current is provided to the gate of the first switch tube; when the sixth drive current is provided to the gate of the first switch tube, when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold, provide a seventh drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be greater than the second increase rate until the first switch tube is turned on; wherein the second increase rate is the increase rate of the gate voltage of the first switch tube when the sixth drive current is provided to the gate of the first switch tube, and the fifth threshold is less than the operating voltage of the bus. In the present application, when the turn-on time of the first switch tube arrives, the power conversion device controls the gate voltage of the first switch tube to increase through the controller, and controls the increase rate of the gate voltage of the first switch tube to decrease when the gate voltage of the first switch tube is greater than or equal to the fourth threshold, which can effectively reduce the generation of current stress and EMI. Furthermore, when the voltage difference between the two ends of the first switch tube of the power conversion device is less than or equal to the fifth threshold, the increase rate of the gate voltage of the first switch tube is increased by controlling the controller until the first switch tube is fully turned on, which can reduce the generation of current stress and EMI while increasing the conduction speed of the first switch tube, thereby reducing the conduction loss.

[0015] In combination with the ninth possible implementation of the first aspect, in a tenth possible implementation, the controller is used to: obtain the current magnitude of the fifth drive current and the current magnitude of the seventh drive current based on the gate drive current used to control the first switch tube to turn on at the target turn-on speed. In the present application, the controller can obtain the current magnitudes of the fifth drive current and the seventh drive current based on the gate drive current corresponding to the target turn-on speed. Furthermore, when the controller drives the first switch tube based on the fifth drive current or the seventh drive current, the gate voltage of the first switch tube can be rapidly increased, thereby further improving the turn-on speed of the first switch tube and effectively reducing the turn-on loss.

[0016] In a second aspect, the present application also provides a control method for a power conversion device, the power conversion device comprising a first switch tube and a second switch tube connected in series; the first electrode of the first switch tube is connected to the second switch tube, and the second electrode of the first switch tube is grounded or connected to a bus, the method comprising: when the turn-off moment of the first switch tube arrives, providing a first drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to a first threshold, providing a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase; when the second drive current is provided to the gate of the first switch tube, when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, or when the time length of providing the second drive current to the gate of the first switch tube is greater than or equal to the time threshold, providing a third drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease until the first switch tube is turned off.

[0017] In combination with the second aspect, in a first possible implementation, the method also includes: obtaining the gate voltage of the first switching tube when providing the first driving current to the gate of the first switching tube, and providing a fourth driving current to the gate of the first switching tube when the gate voltage of the first switching tube is less than or equal to a third threshold value, so as to control the decrease rate of the gate voltage of the first switching tube to be less than the first decrease rate, wherein the first decrease rate is the decrease rate of the gate voltage of the first switching tube when the first driving current is provided to the gate of the first switching tube.

[0018] In combination with any one of the second aspect to the first possible implementation of the second aspect, in a second possible implementation, the method includes: obtaining the current magnitude of the first drive current and the current magnitude of the third drive current based on the gate drive current used to control the first switch tube to be turned off at a target turn-off speed.

[0019] In combination with any one of the second possible implementations of the second aspect to the second aspect, in a third possible implementation, the method includes: after providing a first drive current to the gate of the first switching tube, detecting the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and obtaining the magnitude of the second drive current based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

[0020] In combination with any one of the second possible implementations of the second aspect to the second aspect, in a fourth possible implementation, the method includes: after providing a first drive current to the gate of the first switching tube, detecting the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, and obtaining the magnitude of the second drive current based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0021] In combination with any one of the second possible implementations of the second aspect to the second aspect, in a fifth possible implementation, the method includes: when providing a second drive current to the gate of the first switching tube, adjusting the current size of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

[0022] In combination with any one of the second possible implementations of the second aspect to the second aspect, in a sixth possible implementation, the method includes: when providing a second drive current to the gate of the first switching tube, adjusting the magnitude of the second drive current based on the length of time for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0023] In combination with any one of the second aspect to the sixth possible implementation of the second aspect, in a seventh possible implementation, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and obtaining a time threshold based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

[0024] In combination with any one of the second aspect to the sixth possible implementation of the second aspect, in an eighth possible implementation, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, and obtaining a time threshold based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0025] In combination with any one of the second aspect to the eighth possible implementation manner of the second aspect, in a ninth possible implementation manner, the method includes: when the turn-on moment of the first switch tube arrives, providing a fifth drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, providing a sixth drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be less than a first increase rate, and the first increase rate is the increase rate of the gate voltage of the first switch tube when the fifth drive current is provided to the gate of the first switch tube; when the sixth drive current is provided to the gate of the first switch tube, when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold, providing a seventh drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be greater than the second increase rate until the first switch tube is turned on; wherein the second increase rate is the increase rate of the gate voltage of the first switch tube when the sixth drive current is provided to the gate of the first switch tube, and the fifth threshold is less than the operating voltage of the bus.

[0026] In combination with the ninth possible implementation of the second aspect, in a tenth possible implementation, the method includes: obtaining the current magnitude of the fifth drive current and the current magnitude of the seventh drive current based on the gate drive current used to control the first switch tube to be turned on at a target conduction speed.

[0027] In combination with the second possible implementation of the second aspect, in an eleventh possible implementation, the method also includes: obtaining multiple voltage thresholds based on the operating voltage of the bus, the voltage threshold being less than the operating voltage of the bus; while providing a sixth drive current to the gate of the first switch tube, traversing multiple voltage thresholds to use each voltage threshold as a candidate voltage threshold, and when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the candidate voltage threshold, providing a seventh drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase until the first switch tube is turned on; obtaining the current amplitudes of the first electrode and the second electrode corresponding to the candidate voltage threshold during the conduction process of the first switch tube to obtain the current amplitudes of the first electrode and the second electrode corresponding to each voltage threshold; and determining the fifth threshold from the multiple voltage thresholds based on the current amplitudes of the first electrode and the second electrode corresponding to each voltage threshold.

[0028] In a third aspect, the present application provides a switch driver chip, the switch driver chip includes the controller in the first aspect of the present application and any possible implementation manner thereof, the switch driver chip is connected to a first switch tube and a second switch tube; the switch driver chip is used to drive the first switch tube to turn on or off, and to drive the second switch tube to turn on or off. The beneficial effects of the solutions provided in the second and third aspects above can be referred to the description of the first aspect above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the structure of a Buck converter provided in an embodiment of the present application;

[0030] Figure 2 A schematic diagram of a signal waveform of a switch tube provided in an embodiment of the present application;

[0031] Figure 3 Another signal waveform diagram of the switch tube provided in the embodiment of the present application;

[0032] Figure 4 A schematic diagram of a framework of a power conversion device provided in an embodiment of the present application;

[0033] Figure 5 A waveform diagram of a first switch tube provided in an embodiment of the present application;

[0034] Figure 6 Another waveform diagram of the first switch tube provided in an embodiment of the present application;

[0035] Figure 7 Another waveform diagram of the first switch tube provided in the embodiment of the present application;

[0036] Figure 8A schematic diagram of a flow chart of a control method for a power conversion device provided in the present application. DETAILED DESCRIPTION

[0037] The power conversion device provided in the embodiment of the present application is suitable for different application scenarios, such as power supply scenarios such as switching power supply, secondary power supply, tertiary power supply, etc. Among them, the power conversion device includes a first switch tube and a second switch tube connected in series, and the first switch tube and the second switch tube connected in series can be understood as a bridge topology circuit. When the power conversion device is applied in the power supply scenario of the switching power supply, according to the different topological structures connected to the first switch tube and the second switch tube in the power conversion device, the power conversion device can be specifically a boost converter, a buck converter, a buck-boost converter or a resonant converter, etc., then the first switch tube and the second switch tube can be a half-bridge topology circuit in a Boost converter or a Buck converter, or a bridge arm of a full-bridge topology circuit in a Buck-Boost converter or a resonant converter. For ease of understanding, the following content takes the power conversion device as a Buck converter as an example to introduce the power conversion device provided in the embodiment of the present application.

[0038] In some feasible implementations, when the power conversion device provided in the embodiment of the present application is a Buck converter, the structure of the power conversion device can be as follows: Figure 1 For details, please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a Buck converter provided in an embodiment of the present application.

[0039] Figure 1 The Buck converter 100 shown includes a first switch tube Q1, a second switch tube Q2, a first capacitor C1 and a first inductor L1. The first switch tube Q1 and the second switch tube Q2 are connected in series at a first connection point to form a half-bridge switch circuit. One end of the first inductor L1 is connected to the first connection point, and the other end is grounded through the first capacitor C1. The first capacitor C1 is connected in parallel with the load.

[0040] The first switch tube Q1 is connected in series between the first connection point and the ground line, and the second switch tube Q2 is connected in series between the first connection point and the power supply. Alternatively, in other application scenarios, the first switch tube Q1 can be connected in series between the first connection point and the power supply, and the second switch tube Q2 can be connected in series between the first connection point and the ground line. Figure 1 The positions of the first switch tube Q1 and the second switch tube Q2 shown in the figure can be interchanged, and this is not limited in the embodiment of the present application.

[0041] It is understandable that the description of the internal structure of the Buck converter 100 in the embodiment of the present application is only used as an example of a power conversion device. In other application scenarios, the internal structure of the power conversion device may be different depending on the function of the power conversion device.

[0042] It should be noted that the type of the switch tube in the embodiment of the present application may be, but is not limited to, a metal oxide semiconductor field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET), an insulated gate bipolar transistor (Insulate-Gate Bipolar Transistor, IGBT) and a SiC silicon carbide power tube, etc. Specifically, the switch tube may include a first electrode, a second electrode and a control electrode, and the power conversion device may control the conduction or cutoff of the switch tube by the control electrode. When the power conversion device controls the switch tube to be turned on, current can be transmitted between the first electrode and the second electrode of the switch tube, and when the power conversion device controls the switch tube to be cut off, current cannot be transmitted between the first electrode and the second electrode of the switch tube. Taking a MOS tube as an example, the control electrode of the switch tube is a gate, the first electrode of the switch tube may be a source, the second electrode may be a drain, or the first electrode may be a drain, and the second electrode may be a source. Taking an IGBT as an example, the control electrode of the switch tube is a gate, the first electrode of the switch tube may be a collector, the second electrode may be an emitter, or the first electrode may be an emitter, and the second electrode may be a collector.

[0043] The Buck converter 100 also includes a controller, which controls the first switch tube Q1 and the second switch tube Q2 to be alternately turned on and off to control the half-bridge switch circuit to switch to different working states, and enables the first inductor L1 and the first capacitor C1 to charge or freewheel, thereby providing a DC voltage Vout to the load. The DC voltage Vout output by the Buck converter 100 is lower than the input power supply voltage Vbus, that is, the Buck converter 100 can implement step-down conversion to convert the power supply voltage Vbus into the working voltage required by the load and provide it to the load for use.

[0044] For example, in a power grid system, when an AC power grid is connected to a computer room and supplies power, the power supply voltage is usually a medium voltage (such as 10 kV) AC power, while the working voltage of the load is usually a low voltage (such as 220V or 400V) DC power or AC power. Therefore, the power grid system can be provided with a Buck converter 100 to step down the voltage connected to the AC power grid to provide the required voltage size and type to the load.

[0045] It should be noted that the power source connected to the Buck converter 100 can be a DC power source or an AC power source (such as the above-mentioned AC power grid). The load connected to the Buck converter 100 can be a device powered by DC power or a device powered by AC power. When the power source is a DC power source and the load is a device powered by DC power, the Buck converter 100 has connection and voltage conversion functions. When the power source is an AC power source and the load is a device powered by DC power, the Buck converter 100 also has a rectification function.

[0046] It is understandable that, as an important component required for the operation of the Buck converter 100, the on and off process of the first switch tube Q1 or the second switch tube Q2 will affect the overall efficiency and performance of the power conversion device.

[0047] In some feasible implementations, when the first switch tube Q1 or the second switch tube Q2 is turned off, the magnitude of the turn-off speed will affect the generation of turn-off loss. Specifically, during the turn-off process of the first switch tube Q1 or the second switch tube Q2, due to the existence of parasitic capacitance, the current flowing through the first switch tube Q1 or the second switch tube Q2 cannot drop to zero immediately, and the voltage across the first switch tube Q1 or the second switch tube Q2 is already increasing, then the voltage and current overlap occurs on the first switch tube Q1 or the second switch tube Q2, resulting in turn-off loss. Exemplarily, the voltage and current changes when the first switch tube Q1 or the second switch tube Q2 is turned off can be referred to Figure 2 As shown, Figure 2 A schematic diagram of a signal waveform of a switch tube provided in an embodiment of the present application. Figure 2 The Ic shown represents the current of the first switch tube Q1 or the second switch tube Q2, and Vq represents the voltage of the first switch tube Q1 or the second switch tube Q2. Figure 2 It can be seen that when the current Ic of the first switch tube Q1 or the second switch tube Q2 decreases, the voltage Vq increases, and then a shadow area where the voltage and current overlap is formed when the first switch tube Q1 or the second switch tube Q2 is turned off. It can be understood that Figure 2 The larger the area of ​​the shaded area formed by the overlap of the voltages Vq and Ic, the greater the turn-off loss of the first switch tube Q1 or the second switch tube Q2.

[0048] Similarly, the conduction loss generated by the first switch tube Q1 or the second switch tube Q2 during the conduction process can refer to the specific implementation of the above-mentioned shutdown process, and the embodiment of the present application will not be described in detail here.

[0049] It is understandable that the Buck converter 100 can reduce the overlapping interval of voltage and current when the first switch tube Q1 or the second switch tube Q2 is turned off by accelerating the turning-off speed of the first switch tube Q1 or the second switch tube Q2 through the controller. Figure 2 The area of ​​the shaded region shown is reduced, thereby reducing the turn-off loss of the first switch tube Q1 or the second switch tube Q2.

[0050] In addition, when the first switch tube Q1 or the second switch tube Q2 is turned off, the magnitude of the turn-off speed will also affect the generation of voltage stress. Specifically, when the first switch tube Q1 or the second switch tube Q2 is turned off, the midpoint voltage of the connection between the first switch tube Q1 and the second switch tube Q2 changes suddenly, causing the voltage at both ends of the first switch tube Q1 or the second switch tube Q2 to suddenly increase or decrease, thereby generating extremely high voltage spike stress, i.e., voltage stress. Excessive voltage stress will damage the first switch tube Q1 or the second switch tube Q2, reducing the service life of the first switch tube Q1 or the second switch tube Q2. At the same time, a large voltage stress will also cause EMI and other problems. Therefore, when the first switch tube Q1 or the second switch tube Q2 is turned off, although the turn-off loss can be reduced by speeding up the turn-off speed, the acceleration of the turn-off speed will cause the first switch tube Q1 or the second switch tube Q2 to generate a large voltage stress, and the generated clutter signal will be enhanced, causing serious EMI and voltage stress problems, affecting the stable operation of the Buck converter 100.

[0051] Similarly, the conduction loss, current stress, EMI, etc. generated by the first switch tube Q1 or the second switch tube Q2 during the conduction process can refer to the specific implementation of the above-mentioned shutdown process, and the embodiments of the present application will not be described in detail here.

[0052] In order to facilitate understanding of the principle of the above-mentioned loss, voltage stress and EMI generated by the first switch tube Q1 and the second switch tube Q2, the following content first introduces the working characteristics of the first switch tube Q1 when it is turned off and on by examples. The working characteristics of the second switch tube Q2 when it is turned off and on can refer to the relevant description of the first switch tube Q1, and the embodiments of the present application will not be repeated here.

[0053] In some feasible implementations, taking the first switch tube Q1 as a MOS tube as an example, combined with Figure 1 and Figure 3 The conduction process of the first switch tube Q1 is described below. Figure 3 Another signal waveform diagram of the switch tube provided in the embodiment of the present application. Figure 3 As shown, after the controller receives a pulse width modulation (PWM) signal for controlling the first switch tube Q1 to be turned on as a high level, the turn-on process of the first switch tube Q1 can be divided into the following four stages:

[0054] In the first stage from t0 to t1, after receiving the PWM signal at a high level, the controller outputs a driving current Ig to the gate of the first switch tube Q1, and the driving current can charge the parasitic capacitance Cgs between the gate and the source of the first switch tube Q1. Since the first switch tube Q1 is not turned on, the current Ic flowing through the first switch tube Q1 and the voltage Vq across the first switch tube Q1 remain unchanged. When the voltage across the parasitic capacitance Cgs is charged so that the gate voltage Vg of the first switch tube Q1 increases from V0 to V1, the first switch tube Q1 meets the turn-on condition and enters the second stage t1-t2.

[0055] In the second stage from t1 to t2, the first switch tube Q1 starts to conduct, and the current Ic flowing through the first switch tube Q1 gradually increases. At this time, the change of current Ic will cause the parasitic inductance of the first switch tube Q1 to produce a voltage change. When the conduction speed of the first switch tube Q1 is faster, the change of current Ic will be greater, and then the voltage change generated by the parasitic inductance of the first switch tube Q1 will be greater. It can be seen that in the second stage, the first switch tube Q1 enters a stage with relatively large current stress. When the current Ic increases to the maximum value, it enters the third stage t2-t3. The gate voltage Vg of the first switch tube Q1 increases to V2 during this period.

[0056] In the third stage t2 to t3, the first switch tube Q1 enters the voltage drop stage, which is also the Miller platform stage. The first switch tube Q1 has not been fully turned on, and the voltage Vq across the first switch tube Q1 drops rapidly. At this time, the change in the voltage Vq across the first switch tube Q1 will affect the conduction loss of the first switch tube Q1. When the gate voltage Vg increases from V2 to V3, it enters the fourth stage t3-t4.

[0057] In the fourth stage from t3 to t4, the driving current continues to charge the parasitic capacitance Cgs of the first switch tube Q1 until the parasitic capacitance Cgs is charged to the maximum voltage. At this time, the gate voltage Vg of the first switch tube Q1 increases to the conduction threshold V4, the conduction degree of the first switch tube Q1 is the largest, and the internal resistance is the smallest, and the conduction process of the first switch tube Q1 ends.

[0058] From the conduction process of the first switch tube Q1, it can be seen that the current Ic changes continuously in the second stage, and the voltage Vq changes continuously in the third stage. When the conduction process of the first switch tube Q1 is shorter, the conduction loss of the first switch tube Q1 is lower, and the corresponding duration of the second stage and the third stage will be shorter. When the duration of the second stage and the third stage is shortened, the change rate of the current Ic in the second stage increases, and the change rate of the voltage Vq in the third stage increases. The rapid change of current and voltage will enhance the clutter signal, causing serious EMI and current stress problems.

[0059] In some possible implementations, such as Figure 3 As shown, after the controller receives a low-level PWM signal for controlling the first switch tube Q1 to turn on, the turn-off process of the first switch tube Q1 can be divided into the following four stages:

[0060] In the fifth stage t5 to t6, the controller stops outputting the driving current Ig to the first switch tube Q1, so that the gate voltage Vg of the first switch tube Q1 starts to decrease from the maximum voltage value V5. In this stage, the first switch tube Q1 has not been turned off. Figure 3 As shown, the channel current Ic of the first switch tube Q1, that is, the current flowing through the first switch tube Q1, will not change. At the same time, the voltage Vq across the first switch tube Q1 will not change significantly. In the fifth stage, the controller can control the gate voltage Vg of the first switch tube Q1 to quickly pull down to reduce the delay of the first switch tube Q1 being turned off, and at the same time reduce the loss of the first switch tube Q1 caused by the increase in internal resistance during this period. That is to say, in the fifth stage, the turn-off speed of the first switch tube Q1 is proportional to the size of the drive current Ic. Furthermore, when the gate voltage Vg of the first switch tube Q1 decreases from the maximum voltage value V5 to V6, the turn-off of the first switch tube Q1 enters the sixth stage.

[0061] In the sixth stage, from t6 to t7, the first switch tube Q1 enters the Miller platform stage, and the current Ic of the first switch tube Q1 remains roughly unchanged. The first switch tube Q1 begins to turn off, and the voltage Vq across the first switch tube Q1 increases accordingly. At this time, the driving current Ig provided by the controller to the first switch tube Q1 will affect the rate of change of the voltage Vq across the first switch tube Q1. Specifically, the larger the driving current Ig provided by the controller, the faster the rate of change of the voltage Vsw at the midpoint where the first switch tube Q1 is connected to the second switch tube Q2, and the faster the rate of change of the voltage Vq across the first switch tube Q1. The larger the driving current Ig provided by the controller, the faster the turn-off speed of the first switch tube Q1 can be correspondingly accelerated, but the EMI and voltage stress of the first switch tube Q1 will be increased. That is to say, in the sixth stage, the voltage stress and EMI generated by the first switch tube Q1 are inversely proportional to the turn-off speed of the first switch tube Q1. Further, when the gate voltage Vg of the first switch tube Q1 decreases from the voltage value V6 to V7, the turn-off of the first switch tube Q1 enters the seventh stage.

[0062] In the seventh stage, from t7 to t8, the first switch tube Q1 enters the current closing stage, and the current Ic of the first switch tube Q1 begins to decrease, and as the current Ic decreases, the voltage Vq across the first switch tube Q1 also decreases. At this time, the driving current Ig provided by the controller to the first switch tube Q1 will have a significant impact on the current Ic of the first switch tube Q1. Specifically, the larger the driving current Ig provided by the controller, the larger the gate voltage Vg of the first switch tube Q1, and the faster the change rate of the current Ic of the first switch tube Q1. The faster the change rate of the current Ic of the first switch tube Q1, the greater the voltage stress of the first switch tube Q1. That is to say, in the seventh stage, the voltage stress generated by the first switch tube Q1 is inversely proportional to the turn-off speed of the first switch tube Q1. Further, when the gate voltage Vg of the first switch tube Q1 decreases from the voltage value V7 to V8, the turn-off of the first switch tube Q1 enters the eighth stage.

[0063] In the eighth stage t8 to t9, the first switch tube Q1 in this stage enters the current cut-off stage, that is, the current Ic of the first switch tube Q1 has been reduced to a negligible level. At this time, the controller can control the gate voltage Vg of the first switch tube Q1 to quickly pull down to reduce the delay of the first switch tube Q1 turning off. The gate voltage Vg of the first switch tube Q1 continues to decrease until it drops to V9, and the shutdown process of the first switch tube Q1 is completed. Among them, the above-mentioned voltage V9 represents the shutdown threshold voltage of the first switch tube, so when the gate voltage Vg of the first switch tube Q1 drops to V9, the first switch tube Q1 is completely turned off.

[0064] To this end, the Buck converter 100 provided in the embodiment of the present application controls the first switch tube Q1 and the second switch tube Q2 to be turned off or turned on through a controller, which can reduce the loss of the first switch tube Q1 and the second switch tube Q2 during the shutdown or conduction process, and at the same time, reduce the generated EMI, voltage stress and current stress, etc., which can extend the service life of the first switch tube Q1 and the second switch tube Q2 and improve the overall efficiency and working performance of the Buck converter 100.

[0065] The above is only an example of the application scenarios of the power conversion device provided by the present application, and is not an exhaustive list. The present application does not limit the application scenarios.

[0066] From the above content, it can be seen that the power conversion device provided in the embodiment of the present application controls the on and off process of the first switch tube and the second switch tube through the controller, which can reduce the loss and improve the problems of EMI and voltage stress. Figures 4 to 7 The working principle of the controller in the power conversion device provided in the present application is illustrated by way of example.

[0067] In some feasible embodiments, the first switch tube and the second switch tube in the power conversion device are connected in series. The other end of the first switch tube connected to the second switch tube can be grounded, and the other end of the second switch tube connected to the first switch tube can be connected to the bus to receive the bus voltage. The above-mentioned bus is the bus in the power conversion device, which can provide the operating voltage required for the operation of each electronic device in the power conversion device. Alternatively, the other end of the first switch tube connected to the second switch tube can be connected to the bus to receive the operating voltage of the bus, and the other end of the second switch tube connected to the first switch tube can be grounded. In other words, the positions of the first switch tube and the second switch tube in the embodiment of the present application can be interchanged, and the embodiment of the present application is not limited to this.

[0068] Specifically, the controller can be connected to the gate of the first switch tube through the current control terminal to provide a driving current to the gate of the first switch tube to control the first switch tube to be turned on or off. At the same time, the controller can be connected to the first electrode of the first switch tube through the first voltage detection terminal to obtain the voltage of the first electrode of the first switch tube. Further, the controller can determine the voltage difference between the first electrode and the second electrode of the first switch tube based on the obtained voltage of the first electrode of the first switch tube.

[0069] It can be understood that, in the embodiment of the present application, the first switch tube is a MOS tube as an example, and the first electrode and the second electrode can be the source and the drain of the first switch tube respectively. The first electrode can be the source, and the second electrode can be the drain, or the first electrode can be the drain, and the second electrode can be the source, and the embodiment of the present application does not limit this.

[0070] For example, Figure 4 As shown, Figure 4 A schematic diagram of a framework of a power conversion device provided in an embodiment of the present application. Figure 4 The power conversion device 400 shown includes a controller 410, a first switch tube Q1, and a second switch tube Q2. The controller 410 is connected to the gate of the first switch tube Q1 through a current control terminal, and is connected to the first electrode of the first switch tube Q1 through a first voltage detection terminal to obtain the voltage of the first electrode of the first switch tube Q1. The first electrode of the first switch tube Q1 is connected to the second switch tube Q2, and the other end of the second switch tube Q2 connected to the first switch tube Q1 is connected to the bus, and the second electrode of the first switch tube Q1 is grounded.

[0071] It should be noted that the power conversion device may also include a variety of other electronic devices for supporting the implementation of functions, such as a filter unit, a rectifier unit, etc., which are not described one by one in the embodiments of the present application. In other application scenarios, the product form and internal circuit structure of the power conversion device can be adjusted according to actual needs.

[0072] In addition, as an electronic device in the power conversion device, the controller is also connected to the above-mentioned busbar and the ground terminal provided in the power conversion device, and the second electrode of the first switch tube is also connected to the ground terminal, that is, the controller can obtain the voltage magnitude of the first electrode and the second electrode of the first switch tube. Therefore, the controller can be connected to the first electrode of the first switch tube through the first voltage detection terminal to obtain the voltage magnitude of the first electrode of the first switch tube, and then the voltage magnitude between the first electrode and the second electrode of the first switch tube can be determined.

[0073] In some feasible implementations, the controller may also obtain the voltage between the first electrode and the second electrode of the first switch tube through an external detection device. The detection device may be connected to the first electrode and the second electrode of the first switch tube, and send the detected voltage of the first electrode and the voltage of the second electrode of the first switch tube to the controller, and the controller may obtain the voltage between the first electrode and the second electrode of the first switch tube based on the received voltage. It should be noted that the above is only an example, and the embodiment of the present application does not limit the specific implementation method of the controller obtaining the voltage between the first electrode and the second electrode of the first switch tube.

[0074] For example, Figure 4 As shown, the controller 410 can obtain the voltage of the first electrode of the first switch tube Q1 through the first voltage detection terminal. Assuming that the controller 410 obtains that the voltage of the first electrode of the first switch tube Q1 is Vx, and since the second electrode is grounded, the controller can determine that the voltage difference between the first electrode and the second electrode of the first switch tube Q1 is equal to Vx-0. Alternatively, if the second electrode of the first switch tube Q1 is connected to the bus, and the operating voltage of the bus is Vy, the controller can determine that the voltage difference between the first electrode and the second electrode of the first switch tube Q1 is equal to Vx-Vy. The above content is only an example and does not constitute a limitation to the embodiments of the present application.

[0075] It is understandable that the controller in the power conversion device can control the first switch tube and the second switch tube to be alternately turned on and off, so that the power conversion device operates and provides the operating voltage to the load. For ease of explanation, the following content is described by taking the controller controlling the turning off and on of the first switch tube as an example. The implementation method of the controller controlling the turning off and on of the second switch tube can refer to the relevant description of the first switch tube, and the embodiment of the present application will not be repeated in detail.

[0076] In some feasible implementations, the principle of the controller controlling the first switch tube to turn off is first introduced.

[0077] It can be seen from the above that the first switch tube has different operating characteristics in different stages of the shutdown process. Figure 3As shown, in the fifth stage, the first switch tube is turned off at a faster rate and does not cause EMI and voltage stress, while in the sixth stage, the first switch tube is turned off at a faster rate and directly causes EMI and voltage stress. Therefore, in order to reduce the generation of voltage stress and EMI while reducing the turn-off loss of the first switch tube, the power conversion device provided in the embodiment of the present application can perform segmented control on the turn-off process of the first switch tube according to the working characteristics of the first switch tube at different stages during the turn-off process, that is, different control methods are performed on the first switch tube at different stages, so that the turn-off speed, voltage stress and EMI of the first switch tube can be reduced at the same time.

[0078] Specifically, when the controller receives a low-level PWM signal for controlling the first switch tube, it indicates that the first switch tube has reached the shutdown moment. At this time, the first switch tube switches from the on state to the off state, and the controller can first provide a first drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop.

[0079] It should be noted that the controller can control the voltage of the gate of the first switch tube to increase or decrease by providing a driving current (such as the above-mentioned first driving current) to the gate of the first switch tube. Among them, when the gate voltage of the first switch tube is greater than or equal to the conduction threshold, the first switch tube is fully turned on. The conduction threshold can be understood as the minimum value of the gate voltage when the first switch tube is fully turned on, that is, when the gate voltage of the first switch tube is less than the conduction threshold, the first switch tube is not fully turned on. Therefore, when the controller controls the first switch tube to be turned on, it is necessary to pull up the gate voltage of the first switch tube to a range greater than or equal to the conduction threshold. Similarly, when the gate voltage of the first switch tube is less than or equal to the turn-off threshold, the first switch tube is completely turned off. The turn-off threshold can be understood as the maximum value of the gate voltage when the first switch tube is fully turned off, that is, when the gate voltage of the first switch tube is greater than the turn-off threshold, the first switch tube is not completely turned off. Therefore, when the controller controls the first switch tube to be turned off, it is necessary to pull down the gate voltage of the first switch tube to a range less than or equal to the turn-off threshold. For different types of first switch tubes, the specific values ​​of their turn-off threshold and turn-on threshold can be flexibly adjusted, and the embodiments of the present application do not limit this.

[0080] Since the on-threshold of the first switch tube is greater than its off-threshold, when the first switch tube switches from the on state to the off state, the controller can control the gate voltage of the first switch tube to decrease until the gate voltage of the first switch tube is less than or equal to the off-threshold, and the first switch tube is completely turned off.

[0081] In some possible implementations, such as Figure 3As shown in FIG. 1 , the first switch tube is quickly turned off in the fifth stage without causing EMI and voltage stress, while the first switch tube is turned off at a faster rate in the sixth stage, which directly causes EMI and voltage stress. To this end, the controller can Figure 3 At the beginning of the fifth stage shown in FIG. 1 , the gate voltage of the first switch tube is controlled to drop rapidly to speed up the turn-off speed of the first switch tube. Figure 3 When the sixth stage shown starts, the controller can control the first switch tube to reduce its turn-off speed in the sixth stage, thereby reducing the drop rate of the gate voltage of the first switch tube to avoid generating large voltage stress and EMI.

[0082] It is understandable that when the switching rate of the first switch tube is relatively slow, that is, the turn-on speed and the turn-off speed are relatively small, the controller can reduce the generation of voltage stress and EMI by controlling the gate voltage of the first switch tube to decrease at different rates in different stages. However, as the requirements of the power conversion equipment for the switching rate of the first switch tube increase, the speed at which the first switch tube is turned off is also getting faster and faster. When the turn-off speed of the first switch tube is very fast, the controller cannot effectively reduce the generation of voltage stress and EMI by simply controlling the decrease rate of the gate voltage of the first switch tube in different stages.

[0083] For example, in order to meet the switching rate requirements of the power conversion device, the controller needs to quickly control the first switch tube to turn off. To this end, when the turn-off time of the first switch tube arrives, the controller provides a driving current to the first switch tube so that the gate voltage of the first switch tube drops rapidly. The turn-off time of the first switch tube can be understood as Figure 3 The fifth stage shown in FIG. 1 begins. Further, at the beginning of the sixth stage, in order to reduce the generation of voltage stress and EMI, the controller can reduce the driving current provided to the first switch tube so as to slow down the rate of decrease of the gate voltage of the first switch tube. However, since the gate voltage of the first switch tube drops too fast in the fifth stage, although the controller slows down the rate of decrease of the first switch tube in the sixth stage, the first switch tube will still generate large voltage stress and EMI.

[0084] To this end, in the power conversion device provided in the embodiment of the present application, when the turn-off moment of the first switch tube arrives, the controller provides a first drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease. Further, the controller can obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection end, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, provide a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase.

[0085] It should be noted that before the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, the first switch tube is quickly turned off without causing voltage stress and EMI. Figure 3 When the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, it indicates that the first switch tube has entered a stage where EMI and voltage stress may be greatly generated, such as Figure 3 At this time, in order to reduce the voltage stress and EMI generation of the first switch tube, the controller can control the gate voltage of the first switch tube to increase to offset the voltage stress caused by the rapid drop of the gate voltage of the first switch tube under the action of the first drive current, thereby effectively reducing the voltage stress and EMI generation.

[0086] Exemplarily, when the turn-off moment of the first switch tube arrives, the controller provides a first driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop rapidly. Further, in order to minimize the voltage stress and EMI that may be caused by the rapid drop of the gate voltage, after the controller detects through the first voltage detection terminal that the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, the controller provides a second driving current to the gate of the first switch tube to increase the gate voltage of the first switch tube. At this time, even if the gate voltage of the first switch tube drops too fast under the drive of the first driving current, the controller controls the gate voltage of the first switch tube to increase through the second driving current after the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, which can offset the negative impact of the rapid drop of the gate voltage of the first switch tube, thereby reducing the voltage stress and EMI generation. If the controller only controls the drop rate of the gate voltage of the first switch tube to slow down, severe voltage stress and EMI may still occur.

[0087] In some possible implementations, such as Figure 3As shown, in the seventh stage, the first switch tube is turned off at a faster rate, which will directly cause EMI and voltage stress to be generated, while in the subsequent eighth stage, the first switch tube is turned off at a faster rate and will not cause EMI and voltage stress to be generated. Therefore, in order to reduce the voltage stress and EMI while accelerating the turn-off speed of the first switch tube to reduce the turn-off loss of the first switch tube, the controller provides a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase. Further, the controller can obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection terminal, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, the controller provides a third drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop rapidly until the gate voltage of the first switch tube is less than or equal to the above-mentioned turn-off threshold, that is, the first switch tube is turned off.

[0088] It should be noted that before the gate voltage of the first switch tube increases so that the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, the first switch tube is in a stage where EMI and voltage stress may be greatly generated, such as Figure 3 When the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, the first switch tube is quickly turned off without causing voltage stress and EMI. Figure 3 In the eighth stage shown, in order to enable the first switch tube to be turned off quickly and reduce the turn-off loss of the first switch tube, the controller can control the gate voltage of the first switch tube to drop rapidly when the voltage difference between the first electrode and the second electrode of the first switch tube is detected by the first voltage detection terminal to be greater than or equal to the second threshold, until the gate voltage of the first switch tube is less than or equal to the turn-off threshold, that is, the first switch tube is turned off.

[0089] Exemplarily, when the controller detects through the first voltage detection terminal that the voltage difference between the first electrode and the second electrode is greater than or equal to the first threshold, the controller provides a second driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase slowly, thereby reducing the voltage stress and EMI generated by the first switch tube. Further, in order to speed up the turn-off speed of the first switch tube to reduce the turn-off loss of the first switch tube, when the controller detects through the first voltage detection terminal that the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the second threshold, the controller provides a third driving current to the gate of the first switch tube, so that the gate voltage of the first switch tube changes from increasing to rapidly decreasing, thereby reducing the turn-off loss of the first switch tube.

[0090] In some feasible embodiments, the controller can also provide a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, while obtaining the time length for the gate of the first switch tube to provide the second drive current, and when the time length of the second drive current is greater than or equal to the time threshold, provide a third drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop rapidly until the gate voltage of the first switch tube is less than or equal to the above-mentioned shutdown threshold, that is, the first switch tube is turned off.

[0091] It can be understood that before the time length during which the controller provides the second driving current to the gate of the first switch tube is less than the above time threshold, the first switch tube is in a stage where EMI and voltage stress may be greatly generated, such as Figure 3 When the controller provides the second driving current to the gate of the first switch tube for a time period greater than or equal to the time threshold, the first switch tube is quickly turned off without causing voltage stress and EMI to be generated, such as Figure 3 In the eighth stage shown, in order to enable the first switch tube to be turned off quickly and reduce the turn-off loss of the first switch tube, the controller can provide a third drive current to the gate of the first switch tube when the time length of providing the second drive current to the gate of the first switch tube is greater than or equal to the above time threshold, so that the gate voltage of the first switch tube changes from rising to falling quickly, thereby reducing the turn-off loss of the first switch tube, until the gate voltage of the first switch tube is less than or equal to the turn-off threshold, that is, the first switch tube is turned off.

[0092] To facilitate understanding of the implementation process of the power conversion device controlling the first switch tube to turn off through the controller, the following contents are combined with Figure 5 To illustrate with an example, Figure 5 A waveform diagram of a first switch tube provided in an embodiment of the present application. Figure 5 The PWM shown is a signal for controlling the shutdown of the first switch tube, Vg is the gate voltage of the first switch tube, Ig is the driving current (such as the first driving current, the second driving current or the third driving current mentioned above) provided by the controller to the gate of the first switch tube, and Vq is the voltage difference between the first electrode and the second electrode of the first switch tube.

[0093] It is understandable that if Figure 5When the T0 moment shown arrives, the controller receives a low-level PWM signal for controlling the first switch tube, indicating that the turn-off moment of the first switch tube has arrived. At this time, the first switch tube switches from the on state to the off state, and the controller can provide the first drive current Isk0 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to decrease from the maximum value Vsk0. The first drive current Isk0 is a pull-down current relative to the gate of the first switch tube, that is, the first drive current Isk0 can pull down the gate voltage of the first switch tube. If combined with Figure 4 As shown, the flow direction of the first driving current Isk0 is Figure 4 In addition, as the first switch tube starts to turn off, the voltage difference Vq between the first electrode and the second electrode of the first switch tube starts to increase from zero.

[0094] When the time T1 arrives, the controller detects through the first voltage detection terminal that the voltage difference Vq between the first electrode and the second electrode of the first switch tube increases to the first threshold value Vst, indicating that the first switch tube has entered a stage where EMI and voltage stress may be generated significantly. In order to reduce the generation of voltage stress and EMI, the controller provides a second drive current Isp to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to increase from Vsk1. Among them, the second drive current Isp is a pull-up current relative to the gate of the first switch tube, that is, the second drive current Isp can pull up the gate voltage of the first switch tube. If combined with Figure 4 As shown, the flow direction of the second driving current Isp is Figure 4 In addition, although the gate voltage of the first switch tube begins to increase, the gate voltage of the first switch tube does not increase to a level greater than or equal to the conduction threshold, so the first switch tube is still in an incompletely turned-off state, and the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to increase.

[0095] It should be noted that although the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to increase, since the controller provides a second pull-up drive current Isp to the gate of the first switch tube, the gate voltage of the first switch tube increases, and the voltage difference Vq of the first switch tube will not suddenly increase during the shutdown process, thereby reducing the voltage stress of the first switch tube and the generation of EMI.

[0096] When the moment T2 arrives, it indicates that the controller detects through the first voltage detection terminal that the voltage difference Vq between the first electrode and the second electrode of the first switch tube increases to the second threshold value Ven, or it can also indicate that the length of time the controller provides the second drive current to the gate of the first switch tube is greater than or equal to the time threshold. At this time, the first switch tube enters a stage where even if it is turned off quickly, it will not cause a significant generation of EMI and voltage stress. In order to speed up the turn-off speed of the first switch tube and reduce the turn-off loss of the first switch tube, the controller provides a third drive current Isk3 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to drop from Vsk3. Among them, the third drive current Isk3 is a pull-down current relative to the gate of the first switch tube, that is, the third drive current Isk3 can pull down the gate voltage of the first switch tube. If combined with Figure 4 As shown, the flow direction of the third driving current Isk3 is Figure 4 In addition, the voltage difference Vq between the first electrode and the second electrode of the first switch tube continues to increase.

[0097] It can be understood that under the pull-down effect of the third driving current Isk3, the gate voltage of the first switch tube drops rapidly until the gate voltage of the first switch tube drops to the turn-off threshold Vsk4, and the first switch tube is completely turned off. At this time, the voltage difference Vq between the first electrode and the second electrode of the first switch tube is equal to the operating voltage Vbus of the bus.

[0098] It should be noted that the specific value-taking methods of the above-mentioned first drive current, second drive current and third drive current, as well as the first threshold, second threshold and time threshold are not described in detail here. In addition, the shut-off process of the second switch tube connected in series with the first switch tube in the power change device can refer to the specific implementation method of the above-mentioned first switch tube, and the embodiments of this application are not repeated here.

[0099] In the embodiment of the present application, when the turn-off time of the first switch tube arrives, the power conversion device controls the gate voltage of the first switch tube to decrease through the controller, and controls the gate voltage of the first switch tube to increase when the voltage difference across the first switch tube reaches the first threshold, which can effectively reduce the generation of voltage stress and EMI. Further, when the voltage difference across the first switch tube of the power conversion device reaches the second threshold, or when the time length of the controller providing the second drive current, that is, the time length of the gate voltage increase of the first switch tube reaches the time threshold, the gate voltage of the first switch tube is controlled by the controller to change from increasing to decreasing until the first switch tube is completely turned off, which can reduce the generation of voltage stress and EMI while increasing the turn-off speed of the first switch tube, thereby reducing the turn-off loss.

[0100] In some feasible implementations, it can be seen from the above content that the first switch tube has different operating characteristics in different stages of the shutdown process. Figure 3 As shown, in the sixth stage, the first switch tube enters the Miller platform stage, at which time, the first switch tube begins to shut down, and the voltage Vq across the first switch tube increases accordingly. The driving current Ig provided by the controller to the first switch tube will affect the rate of change of the voltage Vq across the first switch tube. Specifically, the larger the driving current Ig provided by the controller, the faster the rate of change of the voltage Vq across the first switch tube, and at the same time, the faster the shut-off speed of the first switch tube. In the seventh stage, the first switch tube enters the current closing stage, the current Ic of the first switch tube begins to decrease, and as the current Ic decreases, the voltage Vq across the first switch tube also decreases. At this time, the driving current Ig provided by the controller to the first switch tube will have a more obvious effect on the current Ic of the first switch tube.

[0101] It can be seen that although the first switch tube may generate voltage stress and EMI when it is quickly turned off when entering the above-mentioned Miller platform stage and entering the above-mentioned current shutdown stage, the voltage stress and EMI caused by the rapid shutdown when the first switch tube enters the Miller platform stage will be smaller than that in the current shutdown stage. In order to speed up the shutdown speed of the first switch tube and reduce the shutdown loss, the controller can control the gate voltage of the first switch tube to slowly decrease when the first switch tube enters the above-mentioned Miller platform stage, so as to speed up the shutdown of the first switch tube while reducing the voltage stress and EMI generation. Furthermore, the controller can control the gate voltage of the first switch tube to increase when the first switch tube enters the above-mentioned current shutdown stage to minimize the voltage stress and EMI generation.

[0102] In some feasible implementations, the power conversion device provided in the embodiment of the present application can determine the moment when the first switch tube enters the Miller platform stage and the current shutdown stage through a controller. Specifically, the controller in the power conversion device can be connected to the gate of the first switch tube through the second voltage detection terminal to detect the gate voltage of the first switch tube.

[0103] In some feasible implementations, the controller can also obtain the gate voltage of the first switch tube through an external detection device. The detection device can be connected to the gate of the first switch tube, and send the detected voltage of the gate of the first switch tube to the controller. It should be noted that the above is only an example, and the embodiment of the present application does not limit the specific implementation method of the controller obtaining the gate voltage of the first switch tube. Furthermore, when the controller detects through the second voltage detection terminal that the gate voltage of the first switch tube is less than or equal to the third threshold value, it indicates that the first switch tube enters the above-mentioned Miller platform stage, and the controller can control the decrease rate of the gate voltage of the first switch tube to decrease. Among them, the controller can control the decrease rate of the gate voltage of the first switch tube to decrease, which means that the decrease rate of the gate voltage of the first switch tube is less than the first decrease rate, and the first decrease rate is the decrease rate of the gate voltage of the first switch tube under the action of the first drive current.

[0104] It should be noted that before the gate voltage of the first switch tube is less than or equal to the third threshold, the first switch tube is in a stage where rapid shutdown does not cause voltage stress and EMI. Figure 3 The fifth stage is shown. At this time, the gate voltage of the first switch tube can drop rapidly. Further, when the gate voltage of the first switch tube is less than or equal to the third threshold, it indicates that the first switch tube has entered a stage where EMI and voltage stress may be greatly generated, such as Figure 3 At this time, in order to reduce the voltage stress and EMI generation of the first switch tube and not to affect the turn-off speed of the first switch tube too much, the controller can reduce the drop rate of the gate voltage of the first switch tube by controlling the decrease rate, thereby effectively reducing the voltage stress and EMI generation.

[0105] Exemplarily, when the turn-off moment of the first switch tube arrives, the controller provides a first drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop rapidly. Furthermore, in order to reduce the voltage stress and EMI that may be caused by the rapid drop of the gate voltage, when the controller detects through the second voltage detection terminal that the gate voltage of the first switch tube is less than or equal to the third threshold, the controller provides a fourth drive current to the gate of the first switch tube so that the drop rate of the gate voltage of the first switch tube is reduced. In other words, the drop rate of the gate voltage of the first switch tube driven by the fourth drive current is smaller than the drop rate (i.e., the first drop rate) driven by the first drive current. At this time, since the controller controls the drop rate of the gate voltage of the first switch tube to decrease, the voltage stress and EMI generation can be reduced, and the turn-off speed of the first switch tube will not be affected.

[0106] To facilitate understanding of the implementation process of the power conversion device controlling the first switch tube to turn off through the controller, the following contents are combined with Figure 6To illustrate with an example, Figure 6 Another waveform diagram of the first switch tube provided in the embodiment of the present application. Figure 6 The PWM shown is a signal for controlling the shutdown of the first switch tube, Vg is the gate voltage of the first switch tube, Ig is the driving current provided by the controller to the gate of the first switch tube (such as the first driving current, the second driving current, the third driving current or the fourth driving current mentioned above), and Vq is the voltage difference between the first electrode and the second electrode of the first switch tube.

[0107] It is understandable that if Figure 6 When the T0 moment shown arrives, the controller receives a low-level PWM signal for controlling the first switch tube, indicating that the turn-off moment of the first switch tube has arrived. At this time, the first switch tube switches from the on state to the off state, and the controller can provide the first drive current Isk0 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to decrease from the maximum value Vsk0. The first drive current Isk0 is a pull-down current relative to the gate of the first switch tube, that is, the first drive current Isk0 can pull down the gate voltage of the first switch tube. If combined with Figure 4 As shown, the flow direction of the first driving current Isk0 is Figure 4 In addition, as the first switch tube starts to turn off, the voltage difference Vq between the first electrode and the second electrode of the first switch tube starts to increase from zero.

[0108] When the moment T1 arrives, the controller detects through the second voltage detection terminal that the gate voltage of the first switch tube has dropped to the third threshold value Vsk1, indicating that the first switch tube has entered a stage where EMI and voltage stress may occur. In order to reduce the generation of voltage stress and EMI, while not having too much impact on the turn-off speed of the first switch tube, the controller provides a fourth drive current Isk2 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to slowly drop from Vsk1. Among them, the fourth drive current Isk2 is a pull-down current relative to the gate of the first switch tube, that is, the fourth drive current Isk2 can pull down the gate voltage of the first switch tube. If combined with Figure 4 As shown, the flow direction of the fourth driving current Isk2 is Figure 4 In addition, the fourth drive current Isk2 can be smaller than the first drive current Isk1, so that the drop rate of the gate voltage Vg of the first switch tube after time T1 is smaller than that before time T1. At the same time, the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to increase.

[0109] When the time T2 arrives, the controller detects through the first voltage detection terminal that the voltage difference Vq between the first electrode and the second electrode of the first switch tube increases to the first threshold value Vst, indicating that the first switch tube has entered a stage where EMI and voltage stress may be greatly generated. In order to reduce the generation of voltage stress and EMI, the controller provides a second drive current Isp to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to increase from Vsk2. Among them, the second drive current Isp is a pull-up current relative to the gate of the first switch tube. In addition, although the gate voltage of the first switch tube begins to increase, the gate voltage of the first switch tube does not increase to a value greater than or equal to the conduction threshold, so the first switch tube is still in an incompletely turned-off state, and the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to increase.

[0110] It should be noted that although the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to increase, since the controller provides a second pull-up drive current Isp to the gate of the first switch tube, the gate voltage of the first switch tube increases, and the voltage difference Vq of the first switch tube will not suddenly increase during the shutdown process, thereby reducing the voltage stress of the first switch tube and the generation of EMI.

[0111] When the time T3 arrives, the controller detects through the first voltage detection terminal that the voltage difference Vq between the first electrode and the second electrode of the first switch tube increases to the second threshold value Ven, indicating that the first switch tube has entered a stage where even if it is quickly turned off, it will not cause a significant generation of EMI and voltage stress. In order to speed up the turn-off speed of the first switch tube and reduce the turn-off loss of the first switch tube, the controller provides a third drive current Isk3 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to start to decrease from Vsk3. Among them, the third drive current Isk3 is a pull-down current relative to the gate of the first switch tube. The voltage difference Vq between the first electrode and the second electrode of the first switch tube continues to increase.

[0112] It can be understood that under the pull-down effect of the third drive current Isk3, the gate voltage of the first switch tube drops rapidly. When the time T4 arrives, the gate voltage of the first switch tube drops to the turn-off threshold Vsk4, indicating that the first switch tube is completely turned off. At this time, the voltage difference Vq between the first electrode and the second electrode of the first switch tube is equal to the operating voltage Vbus of the bus.

[0113] It should be noted that the shutdown process of the second switch tube connected in series with the first switch tube in the power changing device can refer to the specific implementation method of the above-mentioned first switch tube, and the embodiment of the present application will not be repeated here.

[0114] In some feasible implementations, in the power conversion device provided in the embodiments of the present application, the controller can determine the size of the above-mentioned first driving current based on the size of the driving current provided to the gate of the first switching tube when controlling the first switching tube to be turned off at a target turn-off speed.

[0115] It can be seen from the above content that when the turn-off moment of the first switch tube arrives, it indicates that the first switch tube has entered a stage where it can be quickly turned off without causing EMI and voltage stress. At this time, the controller can provide a first drive current to the first switch tube so that the gate voltage of the first switch tube drops rapidly. It can be seen that the function of the first drive current is to quickly drive the gate voltage of the first switch tube to drop. Therefore, in order to determine the size of the first drive current, the controller can use multiple to-be-selected drive currents as the gate drive current of the first switch tube to drive the first switch tube to perform multiple turn-off tests. Furthermore, the controller can use a to-be-selected drive current used by the controller as the first drive current when the turn-off speed of the first switch tube reaches the target turn-off speed in multiple turn-off tests.

[0116] It should be noted that the above-mentioned target turn-off speed refers to the minimum turn-off speed of the first switch tube in order to meet the requirements of the power conversion device for the switching rate. In other words, when the turn-off speed of the first switch tube is greater than or equal to the target turn-off speed, the requirements of the power conversion device for the switching rate can be achieved without causing damage to the first switch tube. On the contrary, when the turn-off speed of the first switch tube is less than the target turn-off speed, the requirements of the power conversion device for the switching rate are not achieved.

[0117] Exemplarily, it is assumed that the controller uses Isk10, Isk11 and Isk12 as the above-mentioned multiple candidate drive currents. Further, when the controller provides the candidate drive current Isk10 to the gate of the first switch tube to drive the first switch tube to turn off, the turn-off speed of the first switch tube is obtained as v0. When the controller provides the candidate drive current Isk11 to the gate of the first switch tube to drive the first switch tube to turn off, the turn-off speed of the first switch tube is obtained as v1. When the controller provides the candidate drive current Isk12 to the gate of the first switch tube to drive the first switch tube to turn off, the turn-off speed of the first switch tube is obtained as v2. At this time, it is assumed that the target turn-off speed of the first switch tube is va, and the above v0<v1<va<v2. It can be seen that when the controller provides the candidate drive current Isk12 to the gate of the first switch tube to drive the first switch tube to turn off, the turn-off speed of the first switch tube is greater than the turn-off speed when other candidate drive currents are provided to drive the first switch tube to turn off, and is greater than or equal to the target turn-off speed va of the first switch tube. Meanwhile, when the controller drives the first switch tube to turn off with the candidate driving current, the first switch tube will not be damaged, so the controller can use the candidate driving current Isk12 as the first driving current of the first switch tube.

[0118] In some feasible implementations, in the power conversion device provided in the embodiments of the present application, the controller may determine the magnitude of the third driving current based on the magnitude of the driving current provided to the gate of the first switching tube when controlling the first switching tube to shut down at a target shut-off speed.

[0119] It should be noted that the specific implementation of the controller determining the size of the third drive current can refer to the specific implementation method of determining the size of the first drive current in the above content, and the embodiment of the present application will not repeat this. In addition, the size of the first drive current and the third drive current can be the same or different, and the embodiment of the present application does not limit this.

[0120] In some feasible implementations, the controller may determine the magnitude of the second driving current based on the following content.

[0121] It should be noted that the magnitude of the voltage stress generated by the first switch tube is related to the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, and the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube is related to the load connected to the power conversion device. Specifically, when the load is heavy, that is, the power supply current required by the load is relatively large, in order to provide sufficient power supply current to the load, the voltage difference between the first electrode and the second electrode of the first switch tube will change faster, which will make the voltage stress generated by the first switch tube larger. On the contrary, when the load is light, that is, the power supply current required by the load is relatively small, the voltage difference between the first electrode and the second electrode of the first switch tube will change relatively slowly, and the voltage stress generated by the first switch tube will also be relatively small.

[0122] It can be understood that the voltage difference change rate between the first electrode and the second electrode of the first switch tube can be characterized by the voltage difference change rate between the first electrode and the second electrode of the first switch tube. The voltage difference change rate between the first electrode and the second electrode of the first switch tube refers to the change in the voltage difference between the first electrode and the second electrode of the first switch tube within a certain time range.

[0123] Among them, the greater the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the faster the voltage difference between the first electrode and the second electrode of the first switch tube changes, that is, the faster the voltage difference between the first electrode and the second electrode of the first switch tube increases, it can be seen from the above content that the voltage stress generated by the first switch tube will also be greater. On the contrary, the smaller the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the slower the voltage difference between the first electrode and the second electrode of the first switch tube changes, that is, the slower the voltage difference between the first electrode and the second electrode of the first switch tube increases, it can be seen from the above content that the voltage stress generated by the first switch tube will also be smaller.

[0124] To this end, in an embodiment of the present application, the controller can determine the magnitude of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. Furthermore, when the voltage stress generated by the first switch tube is relatively large, indicating that the load connected to the power conversion device at this time is a heavy load, the controller can increase the output second drive current so that the gate voltage of the first switch tube increases faster, thereby effectively reducing the voltage stress generated by the first switch tube. When the voltage stress generated by the first switch tube is relatively small, indicating that the load connected to the power conversion device at this time is a light load, the controller can reduce the output second drive current so that the gate voltage of the first switch tube increases more slowly, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0125] In some feasible embodiments, when the first switch tube is turned off and the controller provides a first drive current to the gate of the first switch tube, the controller can detect the first electrode voltage of the first switch tube through the first voltage detection terminal to obtain the voltage difference change rate between the first electrode and the second electrode of the first switch tube.

[0126] For example, Figure 5 As shown, after the arrival of time T0, the controller provides the first driving current Isk1 to the gate of the first switch tube. At the same time, the controller detects the first electrode voltage of the first switch tube through the first voltage detection terminal to obtain the voltage difference between the first electrode and the second electrode of the first switch tube. Further, it is assumed that the controller obtains the voltage difference between the first electrode and the second electrode of the first switch tube as Vh1, and after a preset time range, obtains the voltage difference between the first electrode and the second electrode of the first switch tube as Vh2. The controller can obtain the voltage difference change rate dv / dt=(Vh2-Vh1) / T of the first switch tube within the preset time range, where T is the above-mentioned preset time range.

[0127] In some feasible implementations, after the controller provides the fourth driving current to the gate of the first switch tube, the controller may detect the first electrode voltage of the first switch tube through the first voltage detection terminal to obtain the voltage difference change rate between the first electrode and the second electrode of the first switch tube.

[0128] For example, Figure 6 As shown, after the arrival of time T1, the controller provides a fourth drive current Isk2 to the gate of the first switch tube. At the same time, the controller detects the voltage of the first electrode of the first switch tube through the first voltage detection terminal to obtain the voltage difference between the first electrode and the second electrode of the first switch tube. Further, it is assumed that the controller obtains the voltage difference between the first electrode and the second electrode of the first switch tube as Vh1, and after a preset time range, obtains the voltage difference between the first electrode and the second electrode of the first switch tube as Vh2. The controller can obtain the voltage difference change rate dv / dt=(Vh2-Vh1) / T of the first switch tube within the preset time range, where T is the above-mentioned preset time range.

[0129] It is understandable that the controller may also obtain the voltage difference change rate between the first electrode and the second electrode of the first switch tube in other ways, which are not described one by one in the embodiments of the present application.

[0130] In some feasible implementations, after obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube, the controller can determine a driving current value corresponding to the voltage difference change rate as the magnitude of the second driving current based on a preset relationship table. The preset relationship table includes driving current values ​​corresponding to voltage difference change rates of different values. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0131] In the power conversion device provided by the embodiment of the present application, the controller can increase the magnitude of the second drive current when the voltage difference change rate between the first electrode and the second electrode of the first switch tube is relatively large, thereby effectively reducing the voltage stress generated by the first switch tube. The controller can reduce the magnitude of the second drive current when the voltage difference change rate between the first electrode and the second electrode of the first switch tube is relatively small, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0132] Exemplarily, when the controller obtains that the voltage difference change rate between the first electrode and the second electrode of the first switch tube is equal to a1, the controller can determine that the magnitude of the second drive current is Isp1 based on the voltage difference change rate a1. When the controller obtains that the voltage difference change rate between the first electrode and the second electrode of the first switch tube is equal to a2, and a2>a1, the controller can determine that the magnitude of the second drive current is Isp2 based on the voltage difference change rate a2, and Isp2>Isp1.

[0133] In some feasible embodiments, in addition to determining the size of the above-mentioned second driving current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, the controller can also determine it based on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference.

[0134] It should be noted that, from the above content, it can be seen that the magnitude of the voltage stress generated by the first switching tube is related to the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and the magnitude of the change of the voltage difference between the first electrode and the second electrode of the first switching tube can also be characterized by the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference.

[0135] The longer the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the slower the voltage difference between the first electrode and the second electrode of the first switch tube changes, and the smaller the voltage stress generated by the first switch tube. On the contrary, the shorter the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the faster the voltage difference between the first electrode and the second electrode of the first switch tube changes, and the greater the voltage stress generated by the first switch tube.

[0136] To this end, in an embodiment of the present application, the controller can determine the magnitude of the second drive current based on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference. Furthermore, when the voltage stress generated by the first switch tube is relatively large, indicating that the load connected to the power conversion device at this time is a heavy load, the controller can increase the output second drive current so that the gate voltage of the first switch tube increases faster, thereby effectively reducing the voltage stress generated by the first switch tube. When the voltage stress generated by the first switch tube is relatively small, indicating that the load connected to the power conversion device at this time is a light load, the controller can reduce the output second drive current so that the gate voltage of the first switch tube increases more slowly, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0137] In some feasible embodiments, when the first switch tube is turned off and the controller provides a first drive current to the gate of the first switch tube, the controller can detect the first electrode voltage of the first switch tube through the first voltage detection end to obtain the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference.

[0138] For example, Figure 5 As shown, after the arrival of time T0, the controller provides the first driving current Isk1 to the gate of the first switch tube. At the same time, the controller detects the voltage of the first electrode of the first switch tube through the first voltage detection terminal to obtain the voltage difference between the first electrode and the second electrode of the first switch tube. Further, the controller can obtain the time length T used for the voltage difference between the first electrode and the second electrode of the first switch tube to rise from Vh1 to Vh2.

[0139] In some feasible embodiments, after the controller provides the above-mentioned fourth driving current to the gate of the first switching tube, the controller can detect the first electrode voltage of the first switching tube through the first voltage detection end to obtain the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference.

[0140] For example, Figure 6As shown, after the arrival of time T1, the controller provides the fourth drive current Isk2 to the gate of the first switch tube. At the same time, the controller detects the voltage of the first electrode of the first switch tube through the first voltage detection terminal to obtain the voltage difference between the first electrode and the second electrode of the first switch tube. Further, the controller can obtain the time length T used for the voltage difference between the first electrode and the second electrode of the first switch tube to rise from Vh1 to Vh2.

[0141] It is understandable that the controller can also obtain the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference in other ways, and the embodiments of the present application will not be explained one by one here.

[0142] It should be noted that the specific values ​​of the first voltage difference and the second voltage difference can be pre-set in the controller. In practical applications, the specific values ​​of the first voltage difference and the second voltage difference can be calculated based on the operating voltage of the bus and the target off-time of the first switch tube. Specifically, the controller needs to obtain the above-mentioned time length T before the first switch tube is completely turned off, that is, before the voltage at both ends of the first switch tube reaches the operating voltage of the bus, then the first voltage difference and the second voltage difference will be less than the operating voltage of the bus 5V. At the same time, since the controller can obtain the above-mentioned time length T as early as possible during the shutdown process of the first switch tube, so as to adjust the gate voltage of the first switch tube in time, the above-mentioned first voltage difference and second voltage difference pre-set in the controller are usually positively correlated with the target off-time of the first switch tube.

[0143] Exemplarily, assuming that the operating voltage of the bus is 5V, the target off-time of the first switch tube is 100ms, that is, the off-time of the first switch tube is 100ms. When the controller needs to obtain the above-mentioned time length T in the first 40ms of the first switch tube shutdown process, the controller can pre-set the second voltage difference to 5V×(40ms / 100ms)=2V, and the first voltage difference can be 1V. It can be understood that when the shutdown moment of the first switch tube arrives, the controller can detect the voltage difference between the first electrode and the second electrode of the first switch tube, and obtain the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from 1V to 2V, which is the above-mentioned time length T. The above is only an example and does not constitute a limitation to the embodiments of the present application.

[0144] In some feasible implementations, after obtaining the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the controller can determine a driving current value corresponding to the time length as the magnitude of the second driving current based on a preset relationship table. The preset relationship table includes driving current values ​​corresponding to time lengths of different values. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0145] In the power conversion device provided by the embodiment of the present application, the controller can increase the magnitude of the second drive current when the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increases from the first voltage difference to the second voltage difference is relatively short, thereby effectively reducing the voltage stress generated by the first switch tube. The controller can reduce the magnitude of the second drive current when the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increases from the first voltage difference to the second voltage difference is relatively long, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0146] Exemplarily, when the controller obtains that the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference is equal to t1, the controller can determine the magnitude of the second drive current to be Isp1 based on the time length t1. When the controller obtains that the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference is equal to t2, and t2>t1, the controller can determine the magnitude of the second drive current to be Isp2 based on the time length t2, and Isp2<Isp1.

[0147] In some feasible implementations, when the controller sees through the first voltage detection terminal that the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, it can first provide a second drive current to the gate of the first switch tube, and the value of the second drive current can be preset. Further, the controller can obtain the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube when providing the second drive current to the gate of the first switch tube, and adjust the magnitude of the second drive current based on the rate of change of the voltage difference.

[0148] Specifically, when the controller provides the second driving current to the gate of the first switch tube, the first electrode voltage of the first switch tube can be detected through the first voltage detection terminal to obtain the voltage difference change rate between the first electrode and the second electrode of the first switch tube. The specific implementation method of the controller obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube can refer to the above content, and the embodiments of the present application are not described in detail here.

[0149] In some feasible implementations, further, after obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube, the controller can decrease the second drive current provided to the gate of the first switch tube based on the magnitude of the voltage difference change rate until the voltage difference change rate between the first electrode and the second electrode of the first switch tube obtained by the controller reaches the target value, and the second drive current is adjusted. The target value of the voltage difference change rate between the first electrode and the second electrode of the first switch tube can be adjusted according to the needs of the actual application scenario, and the embodiment of the present application is not limited to this.

[0150] In some feasible implementations, after obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube, the controller can also determine a driving current value corresponding to the voltage difference change rate as the target value for adjusting the second driving current based on a preset relationship table. The preset relationship table includes driving current values ​​corresponding to voltage difference change rates of different values. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0151] It can be understood that after determining the target value for adjusting the second drive current, the controller can adjust the second drive current provided to the gate of the first switching tube so that the value of the second drive current can be equal to the above target value, thereby completing the adjustment of the second drive current.

[0152] In some feasible implementations, when the controller sees through the first voltage detection terminal that the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, it can first provide a second drive current to the gate of the first switch tube, and the value of the second drive current can be preset. Further, the controller can obtain the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference when providing the second drive current to the gate of the first switch tube, and adjust the magnitude of the second drive current based on the time length.

[0153] Specifically, when the controller provides the second driving current to the gate of the first switch tube, the first electrode voltage of the first switch tube can be detected through the first voltage detection terminal to obtain the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increasing from the first voltage difference to the second voltage difference. The specific implementation method of the controller obtaining the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increasing from the first voltage difference to the second voltage difference can refer to the above content, and the embodiments of the present application are not described in detail here.

[0154] In some feasible implementations, further, after obtaining the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the controller can decrease the second drive current provided to the gate of the first switch tube based on the size of the time length, until the time length for the voltage difference between the first electrode and the second electrode of the first switch tube obtained by the controller to increase from the first voltage difference to the second voltage difference reaches the target value, and the adjustment of the second drive current is completed. Among them, the target value of the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference can be adjusted according to the needs of the actual application scenario, and the embodiment of the present application is not limited to this.

[0155] In some feasible implementations, after obtaining the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the controller can also determine a driving current value corresponding to the time length as the target value for adjusting the second driving current based on a preset relationship table. The preset relationship table includes driving current values ​​corresponding to time lengths of different values. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0156] It can be understood that after determining the target value for adjusting the second drive current, the controller can adjust the second drive current provided to the gate of the first switching tube so that the value of the second drive current can be equal to the above target value, thereby completing the adjustment of the second drive current.

[0157] In some feasible implementations, the controller may determine the size of the above time threshold based on the following content.

[0158] It should be noted that the length of time that the controller provides the second drive current to the gate of the first switch tube is related to the magnitude of the voltage stress generated by the first switch tube. When the length of time that the controller provides the second drive current to the gate of the first switch tube is longer, that is, the larger the above time threshold is, the more the voltage stress generated by the first switch tube can be reduced. Therefore, the controller can determine the size of the above time threshold based on the magnitude of the voltage stress that may be generated by the first switch tube.

[0159] From the above content, it can be seen that the voltage stress generated by the first switch tube is related to the voltage difference change rate between the first electrode and the second electrode of the first switch tube, and the voltage difference change rate between the first electrode and the second electrode of the first switch tube can be characterized by the voltage difference change rate between the first electrode and the second electrode of the first switch tube.

[0160] It is understandable that the greater the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the faster the voltage difference between the first electrode and the second electrode of the first switch tube changes, that is, the greater the voltage stress generated by the first switch tube, and the longer the time length for which the controller needs to provide the second drive current to the gate of the first switch tube, that is, the greater the above-mentioned time threshold. On the contrary, the smaller the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the slower the voltage difference between the first electrode and the second electrode of the first switch tube changes, that is, the smaller the voltage stress generated by the first switch tube, and the shorter the time length for which the controller needs to provide the second drive current to the gate of the first switch tube, that is, the smaller the above-mentioned time threshold.

[0161] Furthermore, when the voltage difference between the first electrode and the second electrode of the first switch tube has a relatively large change rate, the controller may increase the above time threshold to increase the time length of outputting the second drive current to the gate of the first switch tube, thereby effectively reducing the voltage stress generated by the first switch tube. When the voltage difference between the first electrode and the second electrode of the first switch tube has a relatively small change rate, the controller may reduce the above time threshold to shorten the time length of outputting the second drive current to the gate of the first switch tube, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0162] It should be noted that the specific implementation method of the controller obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube can be found in the above content, and the embodiments of the present application will not be elaborated here.

[0163] In some feasible implementations, after obtaining the voltage difference change rate between the first electrode and the second electrode of the first switch tube, the controller can determine a time length value corresponding to the voltage difference change rate as the size of the above-mentioned time threshold based on a preset relationship table. The preset relationship table includes time length values ​​corresponding to different values ​​of the voltage difference change rate. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0164] In some feasible embodiments, the controller can determine the size of the above-mentioned time threshold based not only on the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, but also on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference.

[0165] It should be noted that, from the above content, it can be seen that the magnitude of the voltage stress generated by the first switching tube is related to the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and the magnitude of the change of the voltage difference between the first electrode and the second electrode of the first switching tube can also be characterized by the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference.

[0166] Among them, the longer the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increases from the first voltage difference to the second voltage difference, the smaller the voltage stress generated by the first switch tube is, and the shorter the time length that the controller needs to provide the second drive current to the gate of the first switch tube is, that is, the smaller the above time threshold is. On the contrary, the shorter the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increases from the first voltage difference to the second voltage difference, the greater the voltage stress generated by the first switch tube is, and the longer the time length that the controller needs to provide the second drive current to the gate of the first switch tube is, that is, the larger the above time threshold is.

[0167] Furthermore, when the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference is relatively short, the controller may increase the above time threshold to increase the time length for outputting the second drive current to the gate of the first switch tube, thereby effectively reducing the voltage stress generated by the first switch tube. When the above time length is relatively long, the controller may reduce the time threshold to shorten the time length for outputting the second drive current to the gate of the first switch tube, thereby appropriately increasing the turn-off speed of the first switch tube while reducing the voltage stress generated by the first switch tube.

[0168] It should be noted that the specific implementation method of the controller obtaining the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increasing from the first voltage difference to the second voltage difference can be referred to the above content, and the embodiments of the present application will not be repeated here.

[0169] In some feasible implementations, after obtaining the time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, the controller can determine a threshold value corresponding to the time length as the size of the above-mentioned time threshold based on a preset relationship table. The preset relationship table includes threshold values ​​corresponding to time lengths of different values. The preset relationship table can be obtained based on multiple shutdown tests or practice summaries of the first switch tube, and the embodiments of the present application are not limited to this.

[0170] In some feasible implementations, the following content introduces the principle of the controller controlling the first switch tube to be turned on.

[0171] It can be seen from the above content that the first switch tube has different working characteristics in different stages of the conduction process. Therefore, in order to reduce the conduction loss of the first switch tube while reducing the generation of current stress and EMI, the power conversion device provided in the embodiment of the present application can perform segmented control on the conduction process of the first switch tube according to the working characteristics of the first switch tube at different stages of the conduction process, that is, different control methods are performed on the first switch tube at different stages, thereby achieving the reduction of conduction speed, current stress and EMI for the first switch tube at the same time.

[0172] Specifically, when the controller receives a high-level PWM signal for controlling the first switch tube, it indicates that the turn-on time of the first switch tube has arrived. At this time, the first switch tube switches from the off state to the on state, and the controller can first provide the fifth drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase rapidly.

[0173] It can be understood that when the first switch tube is turned on, the first switch tube is in a stage where rapid turn-on does not cause EMI and current stress. Figure 3 Therefore, when the turn-on moment of the first switch tube arrives, the controller can provide the fifth driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase rapidly, thereby speeding up the turn-on speed of the first switch tube and reducing the conduction loss of the first switch tube.

[0174] It is understandable that the power conversion device provides different drive currents to the first switch tube through the controller at different stages, so that the gate voltage of the first switch tube has different rising rates at different stages. Figure 3 In the second and third stages shown, the controller is in a stage where current stress and EMI may be generated. To this end, the controller can reduce the conduction speed of the first switch tube by controlling the first switch tube in the second and third stages, thereby reducing the increase rate of the gate voltage of the first switch tube to avoid generating large current stress and EMI.

[0175] In some feasible implementations, after the controller provides the fifth driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase rapidly, the controller may further obtain the gate voltage of the first switch tube through the second voltage detection terminal, and when the gate voltage of the first switch tube is greater than or equal to the fourth threshold, provide the sixth driving current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to decrease. The controller controlling the increase rate of the gate voltage of the first switch tube to decrease means that the increase rate of the gate voltage of the first switch tube is less than the first increase rate, which is the increase rate of the gate voltage of the first switch tube under the action of the fifth driving current.

[0176] It should be noted that before the gate voltage of the first switch tube is greater than or equal to the fourth threshold, the first switch tube is quickly turned off and current stress and EMI will not be generated. Figure 3 When the gate voltage of the first switch tube is greater than or equal to the fourth threshold, it indicates that the first switch tube has entered a stage where EMI and current stress may be greatly generated, such as Figure 3 Therefore, in order to reduce the current stress and EMI generation of the first switch tube, the controller can reduce the rate of increase of the gate voltage of the first switch tube to effectively reduce the current stress and EMI generation.

[0177] Specifically, when the controller detects through the second voltage detection terminal that the gate voltage of the first switch tube is greater than or equal to the fourth threshold, the controller can provide a sixth drive current to the gate of the first switch tube to reduce the rising rate of the gate voltage of the first switch tube.

[0178] In some possible implementations, such as Figure 3 As shown, in the second and third stages, the first switch tube is turned on at a faster speed, which will directly cause EMI and current stress to be generated, while in the subsequent fourth stage, the first switch tube is turned on at a faster speed and will not cause EMI and current stress to be generated. Therefore, in order to reduce the current stress and EMI while speeding up the turn-on speed of the first switch tube to reduce the conduction loss of the first switch tube, after the controller provides the sixth drive current to the gate of the first switch tube, the controller can obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection terminal, and when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold, the controller provides the seventh drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase rapidly until the gate voltage of the first switch tube is greater than or equal to the above-mentioned conduction threshold, that is, the first switch tube is turned on.

[0179] It should be noted that the controller controls the gate voltage of the first switch tube to increase, so that the voltage difference between the first electrode and the second electrode can decrease. Before the voltage difference between the first electrode and the second electrode of the first switch tube decreases to less than or equal to the fifth threshold, the first switch tube is in a stage where EMI and current stress may be greatly generated, such as Figure 3 When the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold, the first switch tube is quickly turned off and on without causing current stress and EMI generation, such as Figure 3 The fourth stage is shown.

[0180] In order to enable the first switch tube to be turned on quickly and reduce the conduction loss of the first switch tube, the controller can provide a seventh drive current to the gate of the first switch tube when it is detected through the first voltage detection end that the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold value, so as to control the gate voltage of the first switch tube to rise quickly until the gate voltage of the first switch tube is greater than or equal to the conduction threshold value, that is, the first switch tube is turned on.

[0181] To facilitate understanding of the implementation process of the power conversion device controlling the first switch tube to be turned on by the controller, the following contents are combined with Figure 7 To illustrate with an example, Figure 7 This is another waveform diagram of the first switch tube provided in the embodiment of the present application. Figure 7 The PWM shown is a signal for controlling the conduction of the first switch tube, Vg is the gate voltage of the first switch tube, Ig is the driving current provided by the controller to the gate of the first switch tube (such as the fifth driving current, the sixth driving current or the seventh driving current mentioned above), and Vq is the voltage difference between the first electrode and the second electrode of the first switch tube.

[0182] It is understandable that if Figure 7 When the T0 moment shown arrives, the controller receives a high-level PWM signal for controlling the first switch tube, indicating that the turn-on moment of the first switch tube has arrived. At this time, the first switch tube switches from the off state to the on state, and the controller can provide the fifth drive current Isc1 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to increase from the minimum value Vsc0. Among them, the fifth drive current Isc1 is an upper current relative to the gate of the first switch tube, that is, the fifth drive current Isc1 can pull up the gate voltage of the first switch tube. If combined with Figure 4 As shown, the direction of the fifth driving current Isc1 is Figure 4 In addition, as the first switch tube starts to conduct, the voltage difference Vq between the first electrode and the second electrode of the first switch tube starts to decrease.

[0183] When the time T1 arrives, the controller detects through the first voltage detection terminal that the gate voltage Vg of the first switch tube increases to the fourth threshold value Vsc1, indicating that the first switch tube has entered a stage where EMI and current stress may be generated significantly. In order to reduce the generation of current stress and EMI, the controller provides the sixth drive current Isc2 to the gate of the first switch tube through the current control terminal to control the increase rate of the gate voltage Vg of the first switch tube to decrease. Among them, the sixth drive current Isc2 is a pull-up current relative to the gate of the first switch tube. Since the first switch tube is still in an incompletely turned-on state, the voltage difference Vq between the first electrode and the second electrode of the first switch tube will continue to decrease.

[0184] When the moment T2 arrives, the controller detects through the first voltage detection terminal that the voltage difference Vq between the first electrode and the second electrode of the first switch tube is reduced to the fifth threshold value Vf. At this time, the first switch tube enters a stage where even if it is quickly turned on and off, it will not cause a large amount of EMI and current stress. In order to speed up the conduction speed of the first switch tube and reduce the conduction loss of the first switch tube, the controller provides the seventh drive current Isc3 to the gate of the first switch tube through the current control terminal to control the gate voltage Vg of the first switch tube to rise rapidly from Vsc2. Among them, the seventh drive current Isc3 is a pull-up current relative to the gate of the first switch tube.

[0185] It is understandable that under the pull-up effect of the seventh drive current Isc3, the gate voltage of the first switch tube increases rapidly until it reaches the conduction threshold Vsc3, and the first switch tube is fully turned on. At this time, the voltage difference Vq between the first electrode and the second electrode of the first switch tube is equal to zero.

[0186] It should be noted that the specific value-taking methods of the fifth drive current, the sixth drive current and the seventh drive current, as well as the fourth threshold and the fifth threshold are not described in detail here. In addition, the conduction process of the second switch tube connected in series with the first switch tube in the power change device can refer to the specific implementation method of the first switch tube, and the embodiment of the present application is not repeated here.

[0187] In some feasible implementations, in the power conversion device provided in the embodiments of the present application, the controller may determine the magnitude of the fifth driving current based on the magnitude of the driving current provided to the gate of the first switching tube when controlling the first switching tube to conduct at a target conduction speed.

[0188] It can be seen from the above content that when the turn-on moment of the first switch tube arrives, it indicates that the first switch tube has entered a stage where it can be turned on quickly without causing EMI and current stress. At this time, the controller can provide the fifth drive current to the first switch tube so that the gate voltage of the first switch tube rises rapidly. It can be seen that the role of the fifth drive current is to quickly drive the gate voltage of the first switch tube to increase. Therefore, in order to determine the size of the fifth drive current, the controller can use multiple to-be-selected drive currents as the gate drive current of the first switch tube to drive the first switch tube to perform multiple turn-on tests. Furthermore, the controller can use a to-be-selected drive current used by the controller as the fifth drive current when the turn-on speed of the first switch tube reaches the target turn-on speed in multiple turn-on tests.

[0189] It should be noted that the above-mentioned target on-speed refers to the minimum on-speed of the first switch tube in order to meet the switching rate requirement of the power conversion device. In other words, when the on-speed of the first switch tube is greater than or equal to the target on-speed, the switching rate requirement of the power conversion device can be achieved without causing damage to the first switch tube. On the contrary, when the on-speed of the first switch tube is less than the target on-speed, the switching rate requirement of the power conversion device is not achieved.

[0190] Exemplarily, it is assumed that the controller uses Isc10, Isc11 and Isc12 as the above-mentioned multiple candidate drive currents. Further, when the controller provides the candidate drive current Isc10 to the gate of the first switch tube to drive the first switch tube to turn on, the turn-on speed of the first switch tube is obtained as v0. When the controller provides the candidate drive current Isc11 to the gate of the first switch tube to drive the first switch tube to turn on, the turn-on speed of the first switch tube is obtained as v1. When the controller provides the candidate drive current Isc12 to the gate of the first switch tube to drive the first switch tube to turn on, the turn-off speed of the first switch tube is obtained as v2. At this time, it is assumed that the target turn-on speed of the first switch tube is vb, and the above v0<v1<vb<v2. It can be seen that when the controller provides the candidate drive current Isc12 to the gate of the first switch tube to drive the first switch tube to turn on, the turn-on speed of the first switch tube is greater than the turn-on speed when providing other candidate drive currents to drive the first switch tube to turn off, and is greater than or equal to the target turn-on speed vb of the first switch tube. Meanwhile, when the controller drives the first switch tube to conduct with the candidate driving current, the first switch tube will not be damaged. Therefore, the controller can use the candidate driving current Isc12 as the fifth driving current of the first switch tube.

[0191] In some feasible implementations, in the power conversion device provided in the embodiments of the present application, the controller may determine the magnitude of the seventh driving current based on the magnitude of the driving current provided to the gate of the first switching tube when controlling the first switching tube to turn on at a target shutdown speed.

[0192] It should be noted that the specific implementation of the controller determining the size of the seventh drive current can refer to the specific implementation method of determining the size of the fifth drive current in the above content, and the embodiment of the present application will not repeat this. In addition, the size of the fifth drive current and the seventh drive current can be the same or different, and the embodiment of the present application does not limit this.

[0193] In some feasible implementations, the controller may determine the size of the fifth threshold based on the following content.

[0194] It can be seen from the above content that in the embodiment of the present application, the power conversion device controls the first switch tube to be turned on through the controller, with the purpose of reducing the conduction loss of the first switch tube and reducing the current stress and EMI generated during the conduction process. To this end, the power conversion device can use multiple voltage thresholds as candidate voltage thresholds to detect the current stress and EMI generated by the first switch tube when the candidate voltage threshold is applied during the conduction process of the first switch tube, and then determine the optimal voltage threshold as the fifth threshold.

[0195] Specifically, since the voltage across the first switch tube can be equal to the operating voltage of the bus at most during the conduction process, the value range of the fifth threshold is between the operating voltage of the bus and zero. To this end, the controller can obtain multiple voltage thresholds as candidate voltage thresholds based on the operating voltage of the bus. Exemplarily, the controller can use 1 / N to (N-1) / N of the operating voltage of the bus as the multiple voltage thresholds, where N is a positive integer greater than 1.

[0196] It is understandable that the controller can use a voltage threshold as a candidate voltage threshold, and obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection terminal when providing the above-mentioned sixth drive current to the gate of the first switch tube. When the controller detects that the voltage difference is less than or equal to the candidate voltage threshold, the seventh drive current is provided to the gate of the first switch tube until the first switch tube is fully turned on. Further, the controller traverses the above-mentioned multiple voltage thresholds, that is, uses each voltage threshold as a candidate voltage threshold, and controls the first switch tube to perform multiple full conduction tests respectively.

[0197] At the same time, in order to compare the current stress and EMI generated by the first switch tube during multiple conduction processes, the controller can obtain the current amplitude flowing through the first electrode and the second electrode of the first switch tube during each conduction process, and the change of the current amplitude can be used to characterize the current stress and EMI generated by the first switch tube. For example, the current amplitude of the first switch tube can be as follows: Figure 6 As shown in Is, the smaller the peak value of the current amplitude Is of the first switch tube is, it can be considered that the current stress and EMI generated by the first switch tube are less.

[0198] Therefore, the controller can obtain the current stress and EMI generated by the first switch tube under the control of different voltage thresholds based on the current amplitudes corresponding to the multiple voltage thresholds obtained in multiple full conduction tests. Further, the controller can set a voltage threshold corresponding to the minimum current stress and EMI generated by the first switch tube as the fifth threshold.

[0199] It should be noted that the method for determining the first threshold and the second threshold may also refer to the specific implementation of the fifth threshold, which will not be elaborated in the embodiments of the present application.

[0200] In the embodiment of the present application, when the turn-on time of the first switch tube arrives, the power conversion device controls the gate voltage of the first switch tube to increase through the controller, and controls the increase rate of the gate voltage of the first switch tube to decrease when the gate voltage of the first switch tube is greater than or equal to the fourth threshold, which can effectively reduce the generation of current stress and EMI. Further, when the voltage difference between the two ends of the first switch tube of the power conversion device is less than or equal to the fifth threshold, the controller controls the increase rate of the gate voltage of the first switch tube to increase until the first switch tube is fully turned on, which can reduce the generation of current stress and EMI while increasing the conduction speed of the first switch tube, thereby reducing the conduction loss.

[0201] See also Figure 8 , Figure 8 A schematic diagram of a flow chart of a control method for a power conversion device provided in the present application. The control method for a power conversion device provided in the present application is applicable to Figures 1 to 7 Specifically, the control method of the power conversion device may include the steps of:

[0202] S101. When the turn-off moment of the first switch tube arrives, a first driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to the first threshold, a second driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to increase.

[0203] It should be noted that when the turn-off moment of the first switch tube arrives, the power conversion device provides a first drive current to the gate of the first switch tube through the controller to control the gate voltage of the first switch tube to drop, and when the voltage difference across the first switch tube, that is, the voltage difference between the first electrode and the second electrode, reaches a first threshold, the controller provides a second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, which can effectively reduce the generation of voltage stress and EMI.

[0204] The specific implementation of the above S101 can refer to the above Figures 1 to 7 The implementation method executed by the controller in the embodiment of the present application will not be repeated here.

[0205] S102. When a second driving current is provided to the gate of the first switching tube, when a voltage difference between the first electrode and the second electrode of the first switching tube is greater than or equal to a second threshold, or when a time length for providing the second driving current to the gate of the first switching tube is greater than or equal to a time threshold, a third driving current is provided to the gate of the first switching tube to control the gate voltage of the first switching tube to drop until the first switching tube is turned off.

[0206] It should be noted that the voltage difference at both ends of the first switch tube of the power conversion device, that is, the voltage difference between the first electrode and the second electrode is greater than or equal to the second threshold, or, when the time length for which the controller provides the second drive current to the gate of the first switch tube is greater than or equal to the time threshold, the controller provides a third drive circuit to the gate of the first switch tube to control the gate voltage of the first switch tube from increasing to decreasing until the first switch tube is completely turned off, which can reduce voltage stress and EMI generation while increasing the turn-off speed of the first switch tube, thereby reducing the turn-off loss.

[0207] The specific implementation of S102 can refer to the above Figures 1 to 7 The implementation method executed by the controller in the embodiment of the present application will not be repeated here.

[0208] In an optional embodiment, the method further includes: obtaining the gate voltage of the first switching tube when providing the first driving current to the gate of the first switching tube, and providing a fourth driving current to the gate of the first switching tube when the gate voltage of the first switching tube is less than or equal to a third threshold value, so as to control the decreasing rate of the gate voltage of the first switching tube to be less than a first decreasing rate, wherein the first decreasing rate is the decreasing rate of the gate voltage of the first switching tube when the first driving current is provided to the gate of the first switching tube.

[0209] It can be understood that after the power conversion device provides the first driving current to the gate of the first switching tube, it can obtain the gate voltage of the first switching tube through the controller, and when the gate voltage of the first switching tube is less than or equal to the third threshold, the controller is used to control the decrease rate of the gate voltage of the first switching tube to decrease, thereby reducing the voltage stress and EMI generation while further improving the turn-off speed of the first switching tube and effectively reducing the turn-off loss.

[0210] In an optional embodiment, the method includes: obtaining the current magnitude of the first drive current and the current magnitude of the third drive current based on a gate drive current used to control the first switch tube to be turned off at a target turn-off speed.

[0211] It is understandable that the power conversion device can obtain the current magnitudes of the first drive current and the third drive current through the controller based on the gate drive current corresponding to the target turn-off speed. Further, when the first switch tube is driven based on the first drive current or the third drive current, the gate voltage of the first switch tube can be rapidly reduced, thereby further improving the turn-off speed of the first switch tube and effectively reducing the turn-off loss.

[0212] In an optional embodiment, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and obtaining the magnitude of the second driving current based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

[0213] It is understandable that when the controller drives the first switch tube based on the second drive current, the gate voltage of the first switch tube can be increased to reduce voltage stress and EMI generation. The controller obtains the current size of the second drive current based on the voltage difference change rate between the first electrode and the second electrode of the first switch tube, which is easy to implement and has high accuracy.

[0214] In an optional embodiment, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, and obtaining the magnitude of the second driving current based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0215] It is understandable that when the controller drives the first switch tube based on the second drive current, the gate voltage of the first switch tube can be increased to reduce voltage stress and EMI generation. The controller obtains the current size of the second drive current based on the time length of the voltage difference between the first electrode and the second electrode of the first switch tube increasing from the first voltage difference to the second voltage difference, which is easy to implement and has high accuracy.

[0216] In an optional embodiment, the method includes: when providing the second drive current to the gate of the first switch tube, adjusting the current magnitude of the second drive current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube.

[0217] It can be understood that after providing the second driving current to the first switching tube, the controller can adjust the current size of the second driving current based on the voltage difference change rate between the first electrode and the second electrode of the first switching tube, thereby effectively reducing voltage stress and EMI generation. It is easy to implement and can be adjusted in real time.

[0218] In an optional embodiment, the method includes: when providing a second drive current to the gate of the first switching tube, adjusting the magnitude of the second drive current based on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from a first voltage difference to a second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0219] It can be understood that after providing the second driving current to the first switching tube, the controller can adjust the current size of the second driving current based on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, thereby effectively reducing voltage stress and EMI generation. This is easy to implement and can be adjusted in real time.

[0220] In an optional embodiment, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube, and obtaining a time threshold based on the detected rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

[0221] It is understandable that the controller can determine the value of the above time threshold based on the voltage difference change rate between the first electrode and the second electrode of the first switch tube after providing the first drive current to the first switch tube, which is easy to implement and has high accuracy.

[0222] In an optional embodiment, the method includes: after providing a first driving current to the gate of the first switching tube, detecting the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, and obtaining a time threshold based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

[0223] It can be understood that after providing the first driving current to the first switching tube, the controller can determine the value of the above-mentioned time threshold based on the length of time it takes for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, which is easy to implement and has high accuracy.

[0224] In an optional embodiment, the method further includes: when the turn-on moment of the first switch tube arrives, providing a fifth drive current to the gate of the first switch tube to control the increase of the gate voltage of the first switch tube, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, providing a sixth drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be less than a first increase rate, and the first increase rate is the increase rate of the gate voltage of the first switch tube when the fifth drive current is provided to the gate of the first switch tube; when the sixth drive current is provided to the gate of the first switch tube, when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the fifth threshold, providing a seventh drive current to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be greater than the second increase rate until the first switch tube is turned on; wherein the second increase rate is the increase rate of the gate voltage of the first switch tube when the sixth drive current is provided to the gate of the first switch tube, and the fifth threshold is less than the working voltage of the bus.

[0225] It can be understood that when the power conversion device reaches the turn-on time of the first switch tube, the gate voltage of the first switch tube is controlled to increase through the controller, and when the gate voltage of the first switch tube is greater than or equal to the fourth threshold, the increase rate of the gate voltage of the first switch tube is controlled to decrease, which can effectively reduce the generation of current stress and EMI. Further, when the voltage difference between the two ends of the first switch tube of the power conversion device is less than or equal to the fifth threshold, the increase rate of the gate voltage of the first switch tube is controlled by the controller to increase until the first switch tube is fully turned on, which can reduce the generation of current stress and EMI while increasing the conduction speed of the first switch tube, thereby reducing the conduction loss.

[0226] In an optional embodiment, the method includes: obtaining the current magnitude of the fifth drive current and the current magnitude of the seventh drive current based on the gate drive current used to control the first switch tube to be turned on at a target turn-on speed.

[0227] It is understandable that the controller can obtain the current magnitudes of the fifth drive current and the seventh drive current based on the gate drive current corresponding to the target conduction speed. Further, when the controller drives the first switch tube based on the fifth drive current or the seventh drive current, the gate voltage of the first switch tube can be rapidly increased, thereby further improving the conduction speed of the first switch tube and effectively reducing the conduction loss.

[0228] In an optional embodiment, the method further includes: obtaining multiple voltage thresholds based on the operating voltage of the bus, the voltage threshold being less than the operating voltage of the bus; while providing a sixth drive current to the gate of the first switch tube, traversing multiple voltage thresholds to use each voltage threshold as a candidate voltage threshold, and when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the candidate voltage threshold, providing a seventh drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase until the first switch tube is turned on; obtaining the current amplitudes of the first electrode and the second electrode corresponding to the candidate voltage threshold during the conduction process of the first switch tube to obtain the current amplitudes of the first electrode and the second electrode corresponding to each voltage threshold; and determining a fifth threshold from the multiple voltage thresholds based on the current amplitudes of the first electrode and the second electrode corresponding to each voltage threshold.

[0229] It is understandable that the controller can use a voltage threshold as a candidate voltage threshold, and obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection terminal when providing the above-mentioned sixth drive current to the gate of the first switch tube. When the controller detects that the voltage difference is less than or equal to the candidate voltage threshold, the seventh drive current is provided to the gate of the first switch tube until the first switch tube is fully turned on. Further, the controller traverses the above-mentioned multiple voltage thresholds, that is, uses each voltage threshold as a candidate voltage threshold, and controls the first switch tube to perform multiple full conduction tests respectively.

[0230] At the same time, during each conduction process, the controller can obtain the current amplitude flowing through the first electrode and the second electrode of the first switch tube, and the change of the current amplitude can be used to characterize the current stress and EMI generated by the first switch tube. The controller can obtain the current stress and EMI generated by the first switch tube under different voltage thresholds based on the current amplitudes corresponding to the multiple voltage thresholds obtained in multiple full conduction tests. Furthermore, the controller can use a voltage threshold corresponding to the minimum current stress and EMI generated by the first switch tube under different voltage thresholds as the fifth threshold.

[0231] Based on the same concept, the embodiment of the present application also provides a switch driver chip, which includes the controller in the aforementioned power conversion device. The switch driver chip can be connected to the first switch tube and the second switch tube respectively, and the first switch tube and the second switch tube are turned on or off. The specific implementation of the above switch driver chip can refer to the above Figures 1 to 8 The implementation method executed by the controller in the embodiment of the present application will not be repeated here.

[0232] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0233] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0234] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0235] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0236] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of protection of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A power conversion device, characterized in that: The power conversion device includes a controller, a first switch tube and a second switch tube connected in series; the gate of the first switch tube is connected to the controller, the first electrode of the first switch tube is connected to the second switch tube, and the second electrode of the first switch tube is grounded or connected to a bus, and the controller is used to: When the turn-off moment of the first switch tube arrives, a first driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to a first threshold, a second driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to increase; When the second driving current is provided to the gate of the first switching tube, when the voltage difference between the first electrode and the second electrode of the first switching tube is greater than or equal to the second threshold, or when the time length for providing the second driving current to the gate of the first switching tube is greater than or equal to the time threshold, a third driving current is provided to the gate of the first switching tube to control the gate voltage of the first switching tube to drop until the first switching tube is turned off.

2. The power conversion device according to claim 1, characterized in that: The controller is used to: When the first driving current is provided to the gate of the first switching tube, the gate voltage of the first switching tube is obtained, and when the gate voltage of the first switching tube is less than or equal to a third threshold, a fourth driving current is provided to the gate of the first switching tube to control the decreasing rate of the gate voltage of the first switching tube to be less than a first decreasing rate, where the first decreasing rate is the decreasing rate of the gate voltage of the first switching tube when the first driving current is provided to the gate of the first switching tube.

3. The power conversion device according to claim 1 or 2, characterized in that: The controller is used to: Based on the gate drive current used to control the first switch tube to be turned off at a target turn-off speed, the current magnitude of the first drive current and the current magnitude of the third drive current are obtained.

4. The power conversion device according to any one of claims 1 to 3, characterized in that: The controller is used to: After providing the first driving current to the gate of the first switching tube, the voltage difference change rate between the first electrode and the second electrode of the first switching tube is detected, and the magnitude of the second driving current is obtained based on the detected voltage difference change rate between the first electrode and the second electrode of the first switching tube.

5. The power conversion device according to any one of claims 1 to 3, characterized in that: The controller is used to: After providing the first driving current to the gate of the first switching tube, detecting the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference, and obtaining the magnitude of the second driving current based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; Wherein, the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

6. The power conversion device according to any one of claims 1 to 3, characterized in that: The controller is used to: When the second driving current is provided to the gate of the first switching tube, the current magnitude of the second driving current is adjusted based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switching tube.

7. The power conversion device according to any one of claims 1 to 3, characterized in that: The controller is used to: In the case where the second driving current is provided to the gate of the first switching tube, the magnitude of the second driving current is adjusted based on the time length for the voltage difference between the first electrode and the second electrode of the first switching tube to increase from the first voltage difference to the second voltage difference; Wherein, the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

8. The power conversion device according to any one of claims 1 to 7, characterized in that: The controller is used to: After providing the first driving current to the gate of the first switching tube, the voltage difference change rate between the first electrode and the second electrode of the first switching tube is detected, and the time threshold is obtained based on the detected voltage difference change rate between the first electrode and the second electrode of the first switching tube.

9. The power conversion device according to any one of claims 1 to 7, characterized in that: The controller is used to: After providing the first driving current to the gate of the first switch tube, detecting a time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference, and obtaining the time threshold based on the detected time length for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from the first voltage difference to the second voltage difference; Wherein, the first voltage difference and the second voltage difference are less than the operating voltage of the bus.

10. The power conversion device according to any one of claims 1 to 9, characterized in that: The controller is used to: When the turn-on moment of the first switch tube arrives, a fifth driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, a sixth driving current is provided to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be less than a first increase rate, where the first increase rate is the increase rate of the gate voltage of the first switch tube when the fifth driving current is provided to the gate of the first switch tube; When the sixth driving current is provided to the gate of the first switching tube, when the voltage difference between the first electrode and the second electrode of the first switching tube is less than or equal to the fifth threshold, the seventh driving current is provided to the gate of the first switching tube to control the increase rate of the gate voltage of the first switching tube to be greater than the second increase rate until the first switching tube is turned on; wherein the second increase rate is the increase rate of the gate voltage of the first switching tube when the sixth driving current is provided to the gate of the first switching tube, and the fifth threshold is less than the operating voltage of the bus.

11. The power conversion device according to claim 10, characterized in that: The controller is used to: Based on the gate drive current used to control the first switch tube to be turned on at a target turn-on speed, the current magnitude of the fifth drive current and the current magnitude of the seventh drive current are obtained.

12. A control method for a power conversion device, characterized in that: The power conversion device comprises a first switch tube and a second switch tube connected in series; a first electrode of the first switch tube is connected to the second switch tube, and a second electrode of the first switch tube is grounded or connected to a bus, and the method comprises: When the turn-off moment of the first switch tube arrives, a first driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to decrease, and when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to a first threshold, a second driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to increase; When the second driving current is provided to the gate of the first switching tube, when the voltage difference between the first electrode and the second electrode of the first switching tube is greater than or equal to the second threshold, or when the time length for providing the second driving current to the gate of the first switching tube is greater than or equal to the time threshold, a third driving current is provided to the gate of the first switching tube to control the gate voltage of the first switching tube to drop until the first switching tube is turned off.

13. The control method according to claim 12, characterized in that: The method further comprises: When the turn-on moment of the first switch tube arrives, a fifth driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to increase, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, a sixth driving current is provided to the gate of the first switch tube to control the increase rate of the gate voltage of the first switch tube to be less than a first increase rate, where the first increase rate is the increase rate of the gate voltage of the first switch tube when the fifth driving current is provided to the gate of the first switch tube; When the sixth driving current is provided to the gate of the first switching tube, when the voltage difference between the first electrode and the second electrode of the first switching tube is less than or equal to the fifth threshold, the seventh driving current is provided to the gate of the first switching tube to control the increase rate of the gate voltage of the first switching tube to be greater than the second increase rate until the first switching tube is turned on; wherein the second increase rate is the increase rate of the gate voltage of the first switching tube when the sixth driving current is provided to the gate of the first switching tube, and the fifth threshold is less than the operating voltage of the bus.

14. The control method according to claim 13, characterized in that: The method further comprises: Obtaining a plurality of voltage thresholds based on the operating voltage of the bus, wherein the voltage thresholds are less than the operating voltage of the bus; In the case of providing the sixth driving current to the gate of the first switch tube, traversing the multiple voltage thresholds to use each of the voltage thresholds as a candidate voltage threshold, and when the voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to the candidate voltage threshold, providing a seventh driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to increase until the first switch tube is turned on; Obtaining the current amplitudes of the first electrode and the second electrode corresponding to the candidate voltage threshold during the conduction process of the first switch tube, so as to obtain the current amplitudes of the first electrode and the second electrode corresponding to each voltage threshold; The fifth threshold is determined from the plurality of voltage thresholds based on current amplitudes of the first electrode and the second electrode corresponding to the respective voltage thresholds.

15. A switch driver chip, characterized in that: The switch driving chip comprises the controller according to any one of claims 1 to 11, and the switch driving chip is connected to the first switch tube and the second switch tube; The switch driving chip is used to drive the first switch tube to be turned on or off, and to drive the second switch tube to be turned on or off.

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