Power conversion device and control method therefor, and switch driver chip

Abstract

The present application relates to the technical field of switch control. Provided are a power conversion device and a control method therefor, and a switch driver chip. The power conversion device comprises: a controller, a first switch transistor and a second switch transistor, wherein the controller provides a first drive current to a gate electrode of the first switch transistor when a turning-off moment of the first switch transistor arrives, so as to control the voltage of the gate electrode of the first switch transistor to decrease, and provides a second drive current to the gate electrode of the first switch transistor when a voltage difference of the first switch transistor is greater than or equal to a first threshold, so as to control the voltage of the gate electrode of the first switch transistor to increase; and when the voltage difference of the first switch transistor is greater than or equal to a second threshold, or the length of time within which the second drive current is provided is greater than or equal to a time threshold, the controller provides a third drive current to the gate electrode of the first switch transistor, so as to control the voltage of the gate electrode of the first switch transistor to decrease until the first switch is turned off. The present application can reduce voltage stress and the generation of EMI, and can increase the turning-off speed of a first switch transistor and reduce turning-off loss, thus having high applicability.

Description

Power conversion device, control method thereof, and switch driving chip

[0001] The present application claims priority to the Chinese patent application No. 202411233764.5, filed on September 4, 2024, entitled "Power conversion device, control method thereof, and switch driving chip", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of switch control, in particular to a power conversion device, a control method thereof, and a switch driving chip. BACKGROUND

[0003] A switch tube refers to a power device with good conduction and turn-off characteristics under certain conditions. The power conversion device can realize the conduction and turn-off of the switch tube by applying a control signal to the control end (e.g., gate) of the switch tube. During the turn-off of the switch tube, the channel current of the switch tube and the channel voltage across the switch tube will have an overlapping interval, thereby generating turn-off loss.

[0004] Generally, in order to reduce the turn-off loss of the switch tube, the power conversion device can accelerate the turn-off speed of the switch tube to shorten the overlapping interval of the channel current and the channel voltage of the switch tube, thereby reducing the turn-off loss of the switch tube. However, when the switch tube turns off quickly, the channel voltage across the switch tube changes rapidly, which will cause a large voltage stress across the switch tube, and the generated spurious 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 needs to be solved by those skilled in the art. SUMMARY

[0005] The present application provides a power conversion device, a control method thereof, and a switch driving chip. The power conversion device can reduce the voltage stress and EMI while increasing the turn-off speed of the first switch tube, thereby reducing the turn-off loss, and has strong applicability.

[0006] In a first aspect, the present application provides a power conversion device, comprising a controller, a first switch and a second switch connected in series; a gate electrode of the first switch is connected to the controller, a first electrode of the first switch is connected to the second switch, and a second electrode of the first switch is connected to ground or a bus; the controller is configured to: when a turn-off time of the first switch arrives, provide a first driving current to the gate electrode of the first switch to control a gate voltage of the first switch to drop, and when a voltage difference between the first electrode and the second electrode of the first switch is greater than or equal to a first threshold, provide a second driving current to the gate electrode of the first switch to control the gate voltage of the first switch to rise; when the voltage difference between the first electrode and the second electrode of the first switch is greater than or equal to a second threshold while the second driving current is provided to the gate electrode of the first switch, or when a length of time for which the second driving current is provided to the gate electrode of the first switch is greater than or equal to a time threshold, provide a third driving current to the gate electrode of the first switch to control the gate voltage of the first switch to drop until the first switch is turned off. In the present application, when the turn-off time of the first switch arrives, the controller controls the gate voltage of the first switch to drop, and when the voltage difference between the first switch and the second switch reaches the first threshold, the controller controls the gate voltage of the first switch to rise, which can effectively reduce voltage stress and EMI. Further, when the voltage difference between the first switch and the second switch reaches the second threshold, or when the length of time for which the second driving current is provided by the controller, i.e., the length of time for which the gate voltage of the first switch rises, reaches the time threshold, the controller controls the gate voltage of the first switch to drop from rising to dropping until the first switch is completely turned off, which can improve the turn-off speed of the first switch while reducing voltage stress and EMI, and thus can reduce turn-off loss.

[0007] In combination with the first aspect, in a first possible implementation manner, the controller is configured to: when the first driving current is provided to the gate electrode of the first switch, acquire the gate voltage of the first switch, and when the gate voltage of the first switch is less than or equal to a third threshold, provide a fourth driving current to the gate electrode of the first switch to control a falling rate of the gate voltage of the first switch to be less than a first falling rate, the first falling rate being a falling rate of the gate voltage of the first switch when the first driving current is provided to the gate electrode of the first switch. In the present application, after the first driving current is provided to the gate electrode of the first switch, the controller can acquire the gate voltage of the first switch, and when the gate voltage of the first switch is less than or equal to the third threshold, the controller controls the falling rate of the gate voltage of the first switch to decrease, which can further improve the turn-off speed of the first switch while reducing voltage stress and EMI, and thus can effectively reduce turn-off loss.

[0008] In any of the first aspect to the first possible implementation of the first aspect, in a second possible implementation, the controller is configured to obtain the current size of the first driving current and the current size of the third driving current based on the gate driving current when the first switch tube is controlled to turn off at the target turn-off speed. In this application, the controller can obtain the current size of the first driving current and the third driving current based on the gate driving current corresponding to the target turn-off speed. Further, when the controller drives the first switch tube based on the first driving current or the third driving 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.

[0009] In any of the first aspect to the second possible implementation of the first aspect, in a third possible implementation, the controller is configured to, after providing the first driving current to the gate of the first switch tube, detect the voltage difference change rate of the first electrode and the second electrode of the first switch tube, and obtain the size of the second driving current based on the detected voltage difference change rate of the first electrode and the second electrode of the first switch tube. In this application, when the controller drives the first switch tube based on the second driving current, the gate voltage of the first switch tube can be raised to reduce voltage stress and EMI generation. Wherein, the controller obtains the current size of the second driving current based on the voltage difference change rate of the first electrode and the second electrode of the first switch tube, which is easy to implement and has high accuracy.

[0010] In any of the first aspect to the second possible implementation of the first aspect, in a fourth possible implementation, the controller is configured to, after providing the first driving current to the gate of the first switch tube, detect the time length for the voltage difference of the first electrode and the second electrode of the first switch tube to increase from a first voltage difference to a second voltage difference, and obtain the size of the second driving current based on the detected time length for the voltage difference of 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 this application, when the controller drives the first switch tube based on the second driving current, the gate voltage of the first switch tube can be raised to reduce voltage stress and EMI generation. Wherein, the controller obtains the current size of the second driving current based on the time length for the voltage difference of 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.

[0011] In a fifth possible implementation of any of the first aspect to the second possible implementation of the first aspect, the controller is configured to, in the case that the second driving current is provided to the gate of the first switch tube, adjust the current size of the second driving current based on a voltage difference change rate of the first electrode and the second electrode of the first switch tube. In this application, the controller can adjust the current size of the second driving current based on the voltage difference change rate of the first electrode and the second electrode of the first switch tube after the second driving current is provided to the first switch tube, thereby effectively reducing voltage stress and EMI generation, being easy to implement and being capable of real-time adjustment.

[0012] In a sixth possible implementation of any of the first aspect to the second possible implementation of the first aspect, the controller is configured to, in the case that the second driving current is provided to the gate of the first switch tube, adjust the size of the second driving current based on a time length for the voltage difference of the first electrode and the second electrode of the first switch 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 working voltage of the bus. In this application, the controller can adjust the current size of the second driving current based on the time length for the voltage difference of 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 the second driving current is provided to the first switch tube, thereby effectively reducing voltage stress and EMI generation, being easy to implement and being capable of real-time adjustment.

[0013] In a seventh possible implementation of any of the first aspect to the sixth possible implementation of the first aspect, the controller is configured to, after the first driving current is provided to the gate of the first switch tube, detect a voltage difference change rate of the first electrode and the second electrode of the first switch tube, and obtain a time threshold based on the detected voltage difference change rate of the first electrode and the second electrode of the first switch tube. In this application, the controller can determine the value of the time threshold based on the voltage difference change rate of the first electrode and the second electrode of the first switch tube after the first driving current is provided to the first switch tube, being easy to implement and having high accuracy.

[0014] In an eighth possible implementation of any of the first aspect to the sixth possible implementation of the first aspect, the controller is configured to: after providing the first driving current to the gate electrode of the first switch tube, detect 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 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; and wherein the first voltage difference and the second voltage difference are less than the working voltage of the bus. In this application, the controller can determine the value of the 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 driving current to the first switch tube, which is easy to implement and has high accuracy.

[0015] In a ninth possible implementation of any of the first aspect to the eighth possible implementation of the first aspect, the controller is configured to: when the turn-on time of the first switch tube arrives, provide a fifth driving current to the gate electrode 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 driving current to the gate electrode of the first switch tube to control the increasing rate of the gate voltage of the first switch tube to be less than a first increasing rate, the first increasing rate being the increasing rate of the gate voltage of the first switch tube when the fifth driving current is provided to the gate electrode 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 a fifth threshold while the sixth driving current is provided to the gate electrode of the first switch tube, provide a seventh driving current to the gate electrode of the first switch tube to control the increasing rate of the gate voltage of the first switch tube to be greater than a second increasing rate until the first switch tube is turned on, the second increasing rate being the increasing rate of the gate voltage of the first switch tube when the sixth driving current is provided to the gate electrode of the first switch tube, and the fifth threshold being less than the working voltage of the bus. In this application, the power conversion device controls the gate voltage of the first switch tube to increase when the turn-on time of the first switch tube arrives, and controls the increasing 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 current stress and the generation of EMI. Further, the power conversion device controls the increasing rate of the gate voltage of the first switch tube to increase 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 until the first switch tube is completely turned on, which can improve the turn-on speed of the first switch tube while reducing the current stress and the generation of EMI, and thus can reduce the turn-on loss.

[0016] In a tenth possible implementation of the ninth possible implementation of the first aspect, the controller is configured to obtain the current magnitude of the fifth driving current and the current magnitude of the seventh driving current based on the gate driving current when the first switch tube is controlled to turn on at the target turn-on speed. In this application, the controller can obtain the current magnitudes of the fifth driving current and the seventh driving current based on the gate driving current corresponding to the target turn-on speed. Further, when the first switch tube is driven by the fifth driving current or the seventh driving current, the gate voltage of the first switch tube can be rapidly increased, so as to further improve the turn-on speed of the first switch tube and effectively reduce the turn-off loss.

[0017] In a second aspect, the application further provides a control method of a power conversion device, the power conversion device comprising 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; the method comprises: when a turn-off time of the first switch tube arrives, providing a first driving current to a gate of the first switch tube to control a gate voltage of the first switch tube to drop, and when a 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 driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to rise; when the second driving 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 a second threshold, or when a time length for which the second driving current is provided to the gate of the first switch tube is greater than or equal to a time threshold, providing a third driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop until the first switch tube is turned off.

[0018] In a first possible implementation of the second aspect, the method further comprises: when the first driving current is provided to the gate of the first switch tube, obtaining the gate voltage of the first switch tube, and when the gate voltage of the first switch tube is less than or equal to a third threshold, providing a fourth driving current to the gate of the first switch tube to control a drop rate of the gate voltage of the first switch tube to be less than a first drop rate, the first drop rate being a drop rate of the gate voltage of the first switch tube when the first driving current is provided to the gate of the first switch tube.

[0019] In any one of the second aspect to the first possible implementation of the second aspect, in a second possible implementation, the method comprises: obtaining the current magnitude of the first driving current and the current magnitude of the third driving current based on the gate driving current when the first switch tube is controlled to turn off at a target turn-off speed.

[0020] In a third possible implementation of any of the second aspect to the second possible implementation of the second aspect, the method comprises: after the first driving current is provided to the gate electrode of the first switch tube, detecting a voltage difference change rate of the first electrode and the second electrode of the first switch tube, and obtaining the size of the second driving current based on the detected voltage difference change rate of the first electrode and the second electrode of the first switch tube.

[0021] In a fourth possible implementation of any of the second aspect to the second possible implementation of the second aspect, the method comprises: after the first driving current is provided to the gate electrode of the first switch tube, detecting a time length for the voltage difference of the first electrode and the second electrode of the first switch tube to increase from a first voltage difference to a second voltage difference, and obtaining the size of the second driving current based on the detected time length for the voltage difference of 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.

[0022] In a fifth possible implementation of any of the second aspect to the second possible implementation of the second aspect, the method comprises: in the case that the second driving current is provided to the gate electrode of the first switch tube, adjusting the current size of the second driving current based on the voltage difference change rate of the first electrode and the second electrode of the first switch tube.

[0023] In a sixth possible implementation of any of the second aspect to the second possible implementation of the second aspect, the method comprises: in the case that the second driving current is provided to the gate electrode of the first switch tube, adjusting the size of the second driving current based on the time length for the voltage difference of the first electrode and the second electrode of the first switch 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 working voltage of the bus.

[0024] In a seventh possible implementation of any of the second aspect to the sixth possible implementation of the second aspect, the method comprises: after the first driving current is provided to the gate electrode of the first switch tube, detecting a voltage difference change rate of the first electrode and the second electrode of the first switch tube, and obtaining a time threshold based on the detected voltage difference change rate of the first electrode and the second electrode of the first switch tube.

[0025] In an eighth possible implementation, in combination with any one of the second aspect to the sixth possible implementation of the second aspect, the method comprises: after the first driving current is provided to the gate electrode 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 working voltage of the bus.

[0026] In a ninth possible implementation, in combination with any one of the second aspect to the eighth possible implementation of the second aspect, the method comprises: when the turn-on time of the first switch tube arrives, providing a fifth driving current to the gate electrode of the first switch tube to control the gate voltage of the first switch tube to rise, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold value, providing a sixth driving current to the gate electrode of the first switch tube to control the rising rate of the gate voltage of the first switch tube to be less than a first rising rate, the first rising rate being the rising rate of the gate voltage of the first switch tube when the fifth driving current is provided to the gate electrode 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 a fifth threshold value in the case that the sixth driving current is provided to the gate electrode of the first switch tube, providing a seventh driving current to the gate electrode of the first switch tube to control the rising rate of the gate voltage of the first switch tube to be greater than a second rising rate until the first switch tube is turned on; wherein the second rising rate is the rising rate of the gate voltage of the first switch tube when the sixth driving current is provided to the gate electrode of the first switch tube, and the fifth threshold value is less than the working voltage of the bus.

[0027] In a tenth possible implementation, in combination with the ninth possible implementation of the second aspect, the method comprises: obtaining the current size of the fifth driving current and the current size of the seventh driving current based on the gate driving current when the first switch tube is controlled to be turned on at the target turn-on speed.

[0028] In a twelfth possible implementation, in combination with the second possible implementation of the second aspect, the method further comprises: obtaining a plurality of voltage thresholds based on the operating voltage of the bus, the voltage thresholds being less than the operating voltage of the bus; in the case that the sixth drive current is provided to the gate electrode of the first switch tube, traversing the plurality of voltage thresholds to take each voltage threshold as a candidate voltage threshold, and in the case that 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 the seventh drive current to the gate electrode of the first switch tube to control the gate voltage of the first switch tube to rise until the first switch tube is turned on; obtaining the current amplitude of the first electrode and the second electrode of the first switch tube corresponding to the candidate voltage threshold in the process of turning on to obtain the current amplitude of the first electrode and the second electrode corresponding to each voltage threshold; and determining the fifth threshold from the plurality of voltage thresholds based on the current amplitude of the first electrode and the second electrode corresponding to each voltage threshold.

[0029] In a third aspect, the present application provides a switch driving chip, which comprises the controller in the first aspect of the present application and any possible implementation thereof, and is connected with the first switch tube and the second switch tube; the switch driving chip is configured to drive the first switch tube to turn on or turn off, and is configured to drive the second switch tube to turn on or turn off. The beneficial effects of the solutions provided by the second aspect and the third aspect above can refer to the description of the first aspect above, and will not be described here in detail. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a structural schematic diagram of a Buck converter provided by an embodiment of the present application;

[0031] FIG. 2 is a signal waveform schematic diagram of a switch tube provided by an embodiment of the present application;

[0032] FIG. 3 is another signal waveform schematic diagram of a switch tube provided by an embodiment of the present application;

[0033] FIG. 4 is a frame schematic diagram of a power conversion device provided by an embodiment of the present application;

[0034] FIG. 5 is a waveform schematic diagram of a first switch tube provided by an embodiment of the present application;

[0035] FIG. 6 is another waveform schematic diagram of a first switch tube provided by an embodiment of the present application;

[0036] FIG. 7 is still another waveform schematic diagram of a first switch tube provided by an embodiment of the present application;

[0037] FIG. 8 is a flow schematic diagram of a control method of a power conversion device provided by the present application. DETAILED DESCRIPTION

[0038] The power conversion device provided by the embodiments of the present application is suitable for different application scenarios, such as switching power supply, secondary power supply, tertiary power supply and the like. The power conversion device includes the first switch tube and the second switch tube connected in series, which can be understood as a bridge topology circuit. When the power conversion device is applied to the power supply scenario of the switching power supply, according to the different topologies connected by the first switch tube and the second switch tube in the power conversion device, the power conversion device can be a boost converter, a buck converter, a buck-boost converter or a resonant converter, and the first switch tube and the second switch tube can be a half-bridge topology circuit in the boost converter or the buck converter, or one bridge arm of a full-bridge topology circuit in the buck-boost converter or the resonant converter. For the convenience of understanding, the power conversion device provided by the embodiments of the present application is introduced by taking the buck converter as an example.

[0039] In some possible embodiments, when the power conversion device provided by the embodiments of the present application is a buck converter, the structure of the power conversion device can be as shown in FIG. 1. Specifically, refer to FIG. 1, which is a structure schematic diagram of the buck converter provided by the embodiments of the present application. The buck converter 100 shown in FIG. 1 includes the first switch tube Q1, the second switch tube Q2, the first capacitor C1 and the first inductor L1. The first switch tube Q1 and the second switch tube Q2 are connected in series at the first connection point to form a half-bridge switching circuit. One end of the first inductor L1 is connected to the first connection point, and the other end is connected to the ground 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, 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, that is, the positions of the first switch tube Q1 and the second switch tube Q2 shown in FIG. 1 can be interchanged, and the embodiments of the present application do not limit this.

[0041] It can be understood that the internal structure of the buck converter 100 in the embodiments of the present application is only an example of the power conversion device, and in other application scenarios, the internal structure of the power conversion device is different according to the different functions of the power conversion device.

[0042] It should be noted that the type of switch tube in the embodiments of the present application can be, but is not limited to, a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), and a SiC silicon carbide power tube, etc. Specifically, the switch tube can include a first electrode, a second electrode, and a control electrode, and the power conversion device can control the conduction or cutoff of the switch tube through the control electrode. When the power conversion device controls the switch tube to be conductive, 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 the gate electrode, the first electrode of the switch tube can be the source electrode, and the second electrode can be the drain electrode, or the first electrode can be the drain electrode, and the second electrode can be the source electrode. Taking an IGBT as an example, the control electrode of the switch tube is the gate electrode, the first electrode of the switch tube can be the collector electrode, and the second electrode can be the emitter electrode, or the first electrode can be the emitter electrode, and the second electrode can be the collector electrode.

[0043] The Buck converter 100 further includes a controller, which controls the first switch tube Q1 and the second switch tube Q2 to be conductive and cut off alternately, so as to control the half-bridge switching circuit to switch to different working states, and make the first inductor L1 and the first capacitor C1 charge or freewheel, thereby providing a DC voltage Vout to the load. Among them, 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 realize step-down conversion to convert the power supply voltage Vbus into the working voltage required by the load and provide it for the load to use.

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

[0045] It should be noted that the power supply connected to the Buck converter 100 can be a direct current power supply or an alternating current power supply (such as the alternating current power grid described above). The load connected to the Buck converter 100 can be a device powered by direct current or a device powered by alternating current. When the power supply is a direct current power supply and the load is a device powered by direct current, the Buck converter 100 has the functions of connection and voltage conversion. When the power supply is an alternating current power supply and the load is a device powered by direct current, the Buck converter 100 also has the function of rectification.

[0046] It can be understood that, as an important component required for the operation of the Buck converter 100, the turn-on and turn-off processes 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 possible embodiments, the size of the turn-off speed of the first switch tube Q1 or the second switch tube Q2 when turned off 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 the parasitic capacitance, the current flowing through the first switch tube Q1 or the second switch tube Q2 cannot immediately drop to zero, while the voltage across the first switch tube Q1 or the second switch tube Q2 is already rising, and thus a phenomenon of voltage-current overlap occurs on the first switch tube Q1 or the second switch tube Q2, thereby causing the generation of turn-off loss. For example, the voltage-current change of the first switch tube Q1 or the second switch tube Q2 when turned off can be referred to FIG. 2, which is a signal waveform diagram of a switch tube provided in an embodiment of the present application. In FIG. 2, Ic 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. As shown in FIG. 2, during the process of the current Ic of the first switch tube Q1 or the second switch tube Q2 dropping, the voltage Vq is rising, and thus a shadow area of voltage-current overlap is formed when the first switch tube Q1 or the second switch tube Q2 is turned off. It can be understood that, the larger the area of the shadow area of voltage-current overlap shown in FIG. 2, the greater the turn-off loss of the first switch tube Q1 or the second switch tube Q2.

[0048] Similarly, the turn-on loss of the first switch tube Q1 or the second switch tube Q2 during the turn-on process can be referred to the specific embodiments of the turn-off process described above, and thus will not be described herein again.

[0049] It can be understood that, the Buck converter 100 can accelerate the turn-off speed of the first switch tube Q1 or the second switch tube Q2 by the controller, so as to reduce the overlap area of voltage and current of the first switch tube Q1 or the second switch tube Q2 when turned off, that is, the area of the shadow area shown in FIG. 2 is reduced, and thus the turn-off loss of the first switch tube Q1 or the second switch tube Q2 can be reduced.

[0050] In addition, the size of the turn-off speed of the first switch tube Q1 or the second switch tube Q2 when turned off also affects the generation of voltage stress. Specifically, when the first switch tube Q1 or the second switch tube Q2 is turned off, the voltage at the midpoint connected with the first switch tube Q1 and the second switch tube Q2 changes suddenly, which causes the voltage across the first switch tube Q1 or the second switch tube Q2 to suddenly rise or drop, thereby generating a very high voltage spike stress, i.e., voltage stress. Excessive voltage stress can damage the first switch tube Q1 or the second switch tube Q2 and shorten the service life of the first switch tube Q1 or the second switch tube Q2. At the same time, a larger voltage stress can also cause EMI and other problems. Therefore, although the first switch tube Q1 or the second switch tube Q2 can be turned off by increasing the turn-off speed to reduce the turn-off loss, the increase of the turn-off speed will cause the first switch tube Q1 or the second switch tube Q2 to generate a larger voltage stress, and the generated spurious signal will be enhanced, causing serious EMI and voltage stress problems and affecting the stable operation of the Buck converter 100.

[0051] Similarly, the conduction loss, current stress, and EMI generated by the first switch tube Q1 or the second switch tube Q2 during conduction can be referred to the specific embodiments of the turn-off process described above, and the embodiments of the present application will not be repeated here.

[0052] In order to facilitate understanding of the principle of the first switch tube Q1 and the second switch tube Q2 generating the above-mentioned losses, voltage stress, and EMI, the following content first exemplarily introduces the working characteristics of the first switch tube Q1 when turned off and turned on. The working characteristics of the second switch tube Q2 when turned off and turned on can be referred to the related description of the first switch tube Q1, and the embodiments of the present application will not be repeated here.

[0053] In some possible embodiments, taking the first switch tube Q1 as a MOS tube as an example, the conduction process of the first switch tube Q1 is described in combination with FIG. 1 and FIG. 3, and FIG. 3 is another signal waveform diagram of a switch tube provided by an embodiment of the present application. As shown in FIG. 3, 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 conduction process of the first switch tube Q1 can be divided into the following four stages:

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

[0055] In the second stage t1-t2, the first switch Q1 starts to turn on, and the current Ic flowing through the first switch Q1 gradually rises. At this time, the change of the current Ic will cause the parasitic inductance of the first switch Q1 to generate a voltage change. The faster the turn-on speed of the first switch Q1, the greater the change of the current Ic, and the greater the voltage change caused by the parasitic inductance of the first switch Q1. As can be seen, the first switch Q1 enters a stage with relatively large current stress in the second stage. When the current Ic rises to a maximum value, the third stage t2-t3 is entered. The gate voltage Vg of the first switch Q1 rises to V2 during this period.

[0056] In the third stage t2-t3, the first switch Q1 enters a voltage drop stage, which is also a Miller plateau stage. The first switch Q1 has not yet fully turned on, and the voltage Vq across the first switch Q1 drops rapidly. At this time, the change of the voltage Vq across the first switch Q1 will affect the turn-on loss of the first switch Q1. When the gate voltage Vg rises from V2 to V3, the fourth stage t3-t4 is entered.

[0057] In the fourth stage t3-t4, the driving current continues to charge the parasitic capacitance Cgs of the first switch Q1 until the parasitic capacitance Cgs is charged to a maximum voltage. At this time, the gate voltage Vg of the first switch Q1 rises to the turn-on threshold V4, the first switch Q1 has the maximum turn-on degree and the minimum internal resistance, and the conduction process of the first switch Q1 ends.

[0058] As can be seen from the conduction process of the first switch Q1, the current Ic continuously changes in the second stage, and the voltage Vq continuously changes in the third stage. The shorter the conduction process of the first switch Q1, the lower the turn-on loss of the first switch Q1, and the shorter the duration of the second stage and the third stage. When the duration of the second stage and the third stage is shortened, the change rate of the current Ic in the second stage and the change rate of the voltage Vq in the third stage increase. The rapid change of the current and the voltage will enhance the spur signal and cause serious EMI and current stress problems.

[0059] In some possible embodiments, as shown in FIG. 3, after the controller receives a PWM signal with a low level for controlling the first switch tube Q1 to be turned 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-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 yet, so the channel current Ic of the first switch tube Q1, i.e., the current flowing through the first switch tube Q1, does not change, as shown in FIG. 3. At the same time, the voltage Vq across the first switch tube Q1 also does not change greatly. In the fifth stage, the controller can quickly pull down the gate voltage Vg of the first switch tube Q1 to reduce the delay of the turn-off of the first switch tube Q1, and reduce the loss of the first switch tube Q1 due to the increase of the internal resistance during this period. That is, in the fifth stage, the turn-off speed of the first switch tube Q1 is proportional to the size of the driving current Ig. Further, 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 t6-t7, the first switch tube Q1 enters the Miller plateau stage, and the current Ic of the first switch tube Q1 is substantially maintained unchanged. The first switch tube Q1 starts to turn off, and the voltage Vq across the first switch tube Q1 rises. 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 greater the driving current Ig provided by the controller, the faster the rate of change of the voltage Vsw at the midpoint between the first switch tube Q1 and the second switch tube Q2, and the faster the rate of change of the voltage Vq across the first switch tube Q1. The greater the driving current Ig provided by the controller, the faster the turn-off speed of the first switch tube Q1, but the greater the EMI and voltage stress of the first switch tube Q1. That is, 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 t7-t8, the first switch Q1 enters the current off stage, the current Ic of the first switch Q1 starts to decrease, and with the decrease of the current Ic, the voltage Vq across the first switch Q1 also decreases. At this time, the driving current Ig provided by the controller to the first switch Q1 has a significant effect on the current Ic of the first switch Q1. Specifically, the greater the driving current Ig provided by the controller, the greater the gate voltage Vg of the first switch Q1, and the faster the change rate of the current Ic of the first switch Q1. The faster the change rate of the current Ic of the first switch Q1, the greater the voltage stress of the first switch Q1. That is, in the seventh stage, the voltage stress generated by the first switch Q1 is inversely proportional to the turn-off speed of the first switch Q1. Further, when the gate voltage Vg of the first switch Q1 decreases from the voltage value V7 to V8, the turn-off of the first switch Q1 enters the eighth stage.

[0063] In the eighth stage t8-t9, the first switch Q1 enters the current off stage, that is, the current Ic of the first switch Q1 has decreased to be negligible. At this time, the controller can control the gate voltage Vg of the first switch Q1 to be rapidly pulled down to reduce the delay of the turn-off of the first switch Q1. The gate voltage Vg of the first switch Q1 continues to decrease until it decreases to V9, and the turn-off process of the first switch Q1 is completed. The above-mentioned voltage V9 represents the turn-off threshold voltage of the first switch, so when the gate voltage Vg of the first switch Q1 decreases to V9, the first switch Q1 is completely turned off.

[0064] Therefore, the Buck converter 100 provided by the embodiment of the present application can control the turn-off or turn-on of the first switch Q1 and the second switch Q2 through the controller, so as to reduce the loss of the first switch Q1 and the second switch Q2 in the turn-off or turn-on process, and at the same time, reduce the generated EMI, voltage stress and current stress, etc., so as to prolong the service life of the first switch Q1 and the second switch Q2, and improve the overall efficiency and working performance of the Buck converter 100.

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

[0066] As can be seen from the above, the power conversion device provided by the embodiment of the present application can control the turn-on and turn-off process of the first switch and the second switch through the controller, so as to reduce the loss while improving the problems of EMI and voltage stress. For the sake of understanding, the working principle of the controller in the power conversion device provided by the present application will be illustrated below in combination with FIGS. 4-7.

[0067] In some possible 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 with the second switch tube can be grounded, and the other end of the second switch tube connected with the first switch tube can be connected with the bus to receive the bus voltage. The bus mentioned above is the bus in the power conversion device, and can provide the operating voltage required by each electronic device in the power conversion device. Alternatively, the other end of the first switch tube connected with the second switch tube can be connected with the bus to receive the operating voltage of the bus, and the other end of the second switch tube connected with the first switch tube can be grounded. That is, the positions of the first switch tube and the second switch tube in the embodiments of the present application can be interchanged, and the embodiments of the present application do not limit this.

[0068] Specifically, the controller can connect the gate of the first switch tube through the current control end to provide a driving current to the gate of the first switch tube to control the first switch tube to be turned on or turned off. Meanwhile, the controller can connect the first electrode of the first switch tube through the first voltage detection end 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 the embodiments of the present application take the first switch tube as an example of a MOS tube, and the first electrode and the second electrode mentioned above 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 embodiments of the present application do not limit this.

[0070] For example, as shown in FIG. 4, FIG. 4 is a schematic diagram of a frame of the power conversion device provided by the embodiments of the present application. The power conversion device 400 shown in FIG. 4 includes a controller 410, a first switch tube Q1 and a second switch tube Q2. The controller 410 connects the gate of the first switch tube Q1 through the current control end and connects the first electrode of the first switch tube Q1 through the first voltage detection end 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 with the second switch tube Q2, the other end of the second switch tube Q2 connected with the first switch tube Q1 is connected with the bus, and the second electrode of the first switch tube Q1 is grounded.

[0071] It should be noted that the power conversion device can further include other various electronic devices for supporting the implementation of functions, for example, a filtering unit, a rectifying unit, etc., which will not be 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, the controller, as the electronic device in the power conversion device, is also connected to the bus and the ground end provided in the power conversion device, and the second electrode of the first switch tube is also connected to the ground end, that is, the controller can obtain the voltage 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 end to obtain the voltage of the first electrode of the first switch tube, and then the voltage between the first electrode and the second electrode of the first switch tube can be determined.

[0073] In some possible embodiments, the controller can 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 can 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, so that the controller can 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 specific implementation of the controller to obtain the voltage between the first electrode and the second electrode of the first switch tube is not limited in the embodiments of the present application.

[0074] For example, as shown in FIG. 4, the controller 410 can obtain the voltage of the first electrode of the first switch tube Q1 through the first voltage detection end. Assuming that the controller 410 obtains the voltage of the first electrode of the first switch tube Q1 as 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 working 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 is only an example and does not constitute a limitation on the embodiments of the present application.

[0075] It can be understood that the controller in the power conversion device can control the first switch tube and the second switch tube to alternately conduct and cut off, so that the power conversion device operates and provides the working voltage to the load. For the convenience of description, the following content takes the controller controlling the turn-off and turn-on of the first switch tube as an example for description, and the implementation of the controller controlling the turn-off and turn-on of the second switch tube can refer to the related description of the first switch tube, and the embodiments of the present application do not repeat the description.

[0076] In some possible embodiments, the principle of the controller controlling the turn-off of the first switch tube is first introduced.

[0077] As can be seen from the above, the first switch tube has different working characteristics in different stages of the turn-off process. For example, as shown in FIG. 3, in the fifth stage, the faster turn-off of the first switch tube does not directly cause the generation of EMI and voltage stress, while in the sixth stage, the faster turn-off of the first switch tube directly causes the generation of EMI and voltage stress. Therefore, in order to reduce the voltage stress and the generation of EMI while reducing the turn-off loss of the first switch tube, the power conversion device provided by the embodiments 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 in different stages of the turn-off process, that is, different control modes are performed on the first switch tube in different stages, so that the reduction of the turn-off speed, voltage stress and EMI of the first switch tube can be realized at the same time.

[0078] Specifically, when the controller receives a PWM signal for controlling the first switch tube as low, it indicates that the turn-off time of the first switch tube comes. At this time, the first switch tube switches from the on state to the off state, and the controller can first provide the first switch tube with a first driving current to control the gate voltage of the first switch tube to drop.

[0079] It should be noted that the controller can control the gate voltage of the first switch tube to rise or drop by providing the first switch tube with a driving current (for example, the first driving current described above). When the gate voltage of the first switch tube is greater than or equal to the turn-on threshold, the first switch tube is fully turned on. The turn-on 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 turn-on threshold, the first switch tube is not fully turned on. Therefore, when the controller controls the first switch tube to turn on, the gate voltage of the first switch tube needs to be pulled up to a range greater than or equal to the turn-on 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 fully 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 fully turned off. Therefore, when the controller controls the first switch tube to turn off, the gate voltage of the first switch tube needs to be pulled down to a range less than or equal to the turn-off threshold. The specific values of the turn-off threshold and the turn-on threshold of the first switch tube can be flexibly adjusted for different types of first switch tubes, which are not limited by the embodiments of the present application.

[0080] Since the turn-on threshold of the first switch tube is greater than the turn-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 drop until the gate voltage of the first switch tube is less than or equal to the turn-off threshold, and the first switch tube is fully turned off.

[0081] In some possible embodiments, as shown in FIG. 3, the fast turn-off of the first switch tube in the fifth stage does not directly cause the generation of EMI and voltage stress, and the fast turn-off of the first switch tube in the sixth stage directly causes the generation of EMI and voltage stress. Therefore, at the beginning of the fifth stage shown in FIG. 3, the controller can control the gate voltage of the first switch tube to decrease rapidly to accelerate the turn-off speed of the first switch tube. At the beginning of the sixth stage shown in FIG. 3, the controller can control the turn-off speed of the first switch tube in the sixth stage to decrease, thereby reducing the decrease rate of the gate voltage of the first switch tube, and avoiding the generation of large voltage stress and EMI.

[0082] It can be understood that, in the case that the switching speed of the first switch tube is relatively slow, i.e., 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 requirement of the power conversion device for the switching speed of the first switch tube increases, the turn-off speed of the first switch tube is also increasing. In the case that the turn-off speed of the first switch tube is fast, the controller cannot effectively reduce the generation of voltage stress and EMI by merely controlling the decrease rate of the gate voltage of the first switch tube in different stages.

[0083] For example, in order to meet the requirement of the power conversion device for the switching speed, the controller needs to quickly control the turn-off of the first switch tube. Therefore, at the moment when the turn-off of the first switch tube is to be performed, the controller provides a driving current to the first switch tube, so that the gate voltage of the first switch tube decreases rapidly. The moment when the turn-off of the first switch tube is to be performed can be understood as the beginning of the fifth stage shown in FIG. 3. Further, at the beginning of the sixth stage, in order to reduce the generation of voltage stress and EMI, the controller can decrease the driving current provided to the first switch tube, so that the decrease rate of the gate voltage of the first switch tube is slowed down. However, since the gate voltage of the first switch tube decreases too fast in the fifth stage, although the controller slows down the decrease rate of the first switch tube in the sixth stage, the first switch tube still generates large voltage stress and EMI.

[0084] Therefore, in the power conversion device provided by the embodiments of the present application, at the moment when the turn-off of the first switch tube is to be performed, the controller provides a first driving current to the gate of the first switch tube to control the decrease of the gate voltage of the first switch tube, and further, the controller can acquire 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 a first threshold value, the controller provides a second driving current to the gate of the first switch tube to control the increase of the gate voltage of the first switch tube.

[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 value, the fast turn-off of the first switch tube will not cause voltage stress and EMI, as shown in the fifth stage of FIG. 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 value, the first switch tube enters a stage where EMI and voltage stress can be generated greatly, as shown in the sixth stage and the seventh stage of FIG. 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 rise to offset the voltage stress caused by the fast drop of the gate voltage of the first switch tube under the action of the first drive current, thereby effectively reducing the generation of voltage stress and EMI.

[0086] For example, the controller provides the first drive current to the gate of the first switch tube when the turn-off time of the first switch tube comes, to control the fast drop of the gate voltage of the first switch tube. Further, in order to reduce the voltage stress and EMI that can be caused by the fast drop of the gate voltage to the greatest extent, after the controller detects 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 value through the first voltage detection terminal, the controller provides the second drive current to the gate of the first switch tube to make the gate voltage of the first switch tube rise. At this time, even if the gate voltage of the first switch tube drops too fast under the drive of the first drive current, since the controller controls the gate voltage of the first switch tube to rise through the second drive 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 value, the negative effects caused by the fast drop of the gate voltage of the first switch tube can be offset, thereby reducing the generation of voltage stress and EMI. If the controller only controls the drop rate of the gate voltage of the first switch tube to slow down, serious voltage stress and EMI can still occur.

[0087] In some possible embodiments, as shown in FIG. 3, in the seventh stage, the fast turn-off of the first switch tube directly causes the generation of EMI and voltage stress, and in the subsequent eighth stage, the fast turn-off of the first switch tube does not cause the generation of EMI and voltage stress. Therefore, in order to reduce the voltage stress and EMI generation while speeding up the turn-off speed of the first switch tube to reduce the turn-off loss of the first switch tube, the controller provides the second drive current to the gate of the first switch tube to control the gate voltage of the first switch tube to rise, and 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 value, the controller provides the third drive current to the gate of the first switch tube to control the fast drop of the gate voltage of the first switch tube, until the gate voltage of the first switch tube is less than or equal to the above-mentioned turn-off threshold value, that is, the first switch tube is turned off.

[0088] It should be noted that before the gate voltage of the first switch tube is raised to make the voltage difference between the first electrode and the second electrode of the first switch tube greater than or equal to the second threshold value, the first switch tube is in a stage where EMI and voltage stress can be greatly generated, as shown in the seventh stage of FIG. 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 value, the fast turn-off of the first switch tube will not cause voltage stress and EMI, as shown in the eighth stage of FIG. 3. In order to enable the fast turn-off of the first switch tube and reduce the turn-off loss of the first switch tube, the controller can control the gate voltage of the first switch tube to be rapidly reduced until the gate voltage of the first switch tube is less than or equal to the turn-off threshold value, i.e., the first switch tube is turned off, 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 value.

[0089] For example, the controller provides the second driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to be slowly raised when the voltage difference between the first electrode and the second electrode is detected by the first voltage detection terminal to be greater than or equal to the first threshold value, so as to reduce the voltage stress and EMI generated by the first switch tube. Further, in order to accelerate the turn-off speed of the first switch tube to reduce the turn-off loss of the first switch tube, the controller provides the third driving current to the gate of the first switch tube to make the gate voltage of the first switch tube change from being raised to being rapidly reduced 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 value, so as to reduce the turn-off loss of the first switch tube.

[0090] In some possible embodiments, the controller can also provide the third driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to be rapidly reduced until the gate voltage of the first switch tube is less than or equal to the above-mentioned turn-off threshold value, i.e., the first switch tube is turned off, when the time length for which the second driving current is provided to the gate of the first switch tube is greater than or equal to the time threshold value while the second driving current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to be raised.

[0091] It can be understood that, before the length of time that the controller provides the second driving current to the gate of the first switch tube is less than the above-mentioned time threshold, the first switch tube is in a stage where EMI and voltage stress can be greatly generated, as shown in the seventh stage of Fig. 3. When the length of time that the controller provides the second driving current to the gate of the first switch tube is greater than or equal to the time threshold, the fast turn-off of the first switch tube also does not cause voltage stress and EMI to be generated, as shown in the eighth stage of Fig. 3. In order to enable the first switch tube to be fast turned off and reduce the turn-off loss of the first switch tube, the controller can provide a third driving current to the gate of the first switch tube when the length of time that the controller provides the second driving current to the gate of the first switch tube is greater than or equal to the above-mentioned time threshold, so that the gate voltage of the first switch tube is changed from rising to fast falling, 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] In order to facilitate understanding of the implementation process of the power conversion device controlling the first switch tube to be turned off by the controller, the following content is exemplified in combination with Fig. 5, which is a waveform schematic diagram of the first switch tube provided by an embodiment of the present application. In Fig. 5, the PWM shown in Fig. 5 is a signal for controlling the first switch tube to be turned off, 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 or the third driving current), and Vq is the voltage difference between the first electrode and the second electrode of the first switch tube.

[0093] It can be understood that, when the time T0 shown in Fig. 5 comes, the controller receives the PWM signal for controlling the first switch tube to be low, which represents that the turn-off time of the first switch tube comes. At this time, the first switch tube is switched from the on state to the off state, and the controller can provide the first driving current Isk0 to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to start falling from the maximum value Vsk0. The first driving current Isk0 is a pull-down current relative to the gate of the first switch tube, that is, the first driving current Isk0 can pull down the gate voltage of the first switch tube. If combined with Fig. 4, the flow direction of the first driving current Isk0 is opposite to that of the driving current Ig in Fig. 4. In addition, since the first switch tube starts to be turned off, the voltage difference Vq between the first electrode and the second electrode of the first switch tube starts to increase from zero.

[0094] At the time T1, the controller detects 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 through the first voltage detection terminal, which indicates that the first switch tube enters a stage where EMI and voltage stress can be generated greatly. In order to reduce the generation of voltage stress and EMI, the controller provides the second driving 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. The second driving current Isp is a pull-up current relative to the gate of the first switch tube, that is, the second driving current Isp can pull up the gate voltage of the first switch tube. If combined with FIG. 4, the flow direction of the second driving current Isp is consistent with the flow direction of the driving current Ig in FIG. 4. In addition, although the gate voltage of the first switch tube starts to increase, the gate voltage of the first switch tube does not increase to be greater than or equal to the turn-on threshold value, so the first switch tube is still in the state of not being completely turned off, and the voltage difference Vq between the first electrode and the second electrode of the first switch tube continues 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 continues to increase, the gate voltage of the first switch tube is increased due to the controller providing the pull-up second driving current Isp to the gate of the first switch tube, which in turn will not cause the voltage difference Vq to increase suddenly during the turn-off process of the first switch tube, thereby reducing the generation of voltage stress and EMI of the first switch tube.

[0096] At the time T2, the controller detects 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 through the first voltage detection terminal, or the length of time that the controller provides the second driving current to the gate of the first switch tube is greater than or equal to the time threshold value. At this time, the first switch tube enters a stage where EMI and voltage stress will not be generated greatly even if the first switch tube is turned off quickly. 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 the third driving 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 decrease from Vsk3. The third driving current Isk3 is a pull-down current relative to the gate of the first switch tube, that is, the third driving current Isk3 can pull down the gate voltage of the first switch tube. If combined with FIG. 4, the flow direction of the third driving current Isk3 is opposite to the flow direction of the driving current Ig in FIG. 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 drive current Isk3, the gate voltage of the first switch tube rapidly decreases until the gate voltage of the first switch tube decreases to the off threshold value 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 method of the first drive current, the second drive current and the third drive current, and the first threshold value, the second threshold value and the time threshold value will not be described here. In addition, the off process of the second switch tube connected in series with the first switch tube in the power conversion device can refer to the specific implementation method of the first switch tube, and the embodiments of the present application will not be described here.

[0099] In the embodiments of the present application, when the off moment of the first switch tube of the power conversion device arrives, the gate voltage of the first switch tube is controlled to decrease by the controller, and when the voltage difference between the two ends of the first switch tube reaches the first threshold value, the gate voltage of the first switch tube is controlled to increase, which can effectively reduce the voltage stress and the generation of EMI. Further, when the voltage difference between the two ends of the first switch tube reaches the second threshold value, or when the length of time that the second drive current is provided by the controller, i.e. the length of time that the gate voltage of the first switch tube increases, reaches the time threshold value, the gate voltage of the first switch tube is controlled to decrease by the controller until the first switch tube is completely turned off, which can reduce the voltage stress and the generation of EMI while improving the off speed of the first switch tube, and thus the off loss can be reduced.

[0100] In some feasible embodiments, as known from the above, the first switch tube has different working characteristics in different stages of the off process. As shown in FIG. 3, in the sixth stage, the first switch tube enters the Miller plateau stage, at this time, the first switch tube starts to turn off, and the voltage Vq between the two ends of the first switch tube increases. The drive current Ig provided by the controller to the first switch tube will affect the change rate of the voltage Vq between the two ends of the first switch tube. Specifically, the greater the drive current Ig provided by the controller, the faster the change rate of the voltage Vq between the two ends of the first switch tube, and the faster the off speed of the first switch tube. In the seventh stage, the first switch tube enters the current off stage, the current Ic of the first switch tube starts to decrease, and with the decrease of the current Ic, the voltage Vq between the two ends of the first switch tube also decreases. At this time, the drive 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] Therefore, although the first switch tube may generate voltage stress and EMI in the case of fast turn-off when entering the above-mentioned Miller platform stage and entering the above-mentioned current turn-off stage, compared with the current turn-off stage, the voltage stress and EMI caused by fast turn-off when the first switch tube enters the Miller platform stage will be smaller. In order to speed up the turn-off speed of the first switch tube and reduce the turn-off 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 turn-off of the first switch tube while reducing the generation of voltage stress and EMI. Further, the controller can control the gate voltage of the first switch tube to rise when the first switch tube enters the above-mentioned current turn-off stage, so as to minimize the generation of voltage stress and EMI.

[0102] In some possible embodiments, the power conversion device provided by the embodiments of the present application can determine the time when the first switch tube enters the Miller platform stage and enters the current turn-off stage through the controller. Specifically, the controller in the power conversion device can be connected with the gate of the first switch tube through the second voltage detection end, so as to detect the gate voltage of the first switch tube.

[0103] In some possible embodiments, the controller can also obtain the size of the gate voltage of the first switch tube through an external detection device. The detection device can be connected with the gate of the first switch tube, and send the detected size of the gate voltage of the first switch tube to the controller. It should be noted that the above is only an example, and the embodiments of the present application do not limit the specific implementation of the controller to obtain the size of the gate voltage of the first switch tube. Further, when the controller detects that the gate voltage of the first switch tube is less than or equal to the third threshold value through the second voltage detection end, it indicates that the first switch tube enters the above-mentioned Miller platform stage, and then the controller can control the decrease rate of the gate voltage of the first switch tube to decrease. Wherein, the controller controlling the decrease rate of the gate voltage of the first switch tube to decrease 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 driving current.

[0104] It should be noted that before the gate voltage of the first switch is less than or equal to the third threshold value, the first switch is in a stage where the fast turn-off of the first switch does not cause voltage stress and EMI, as shown in the fifth stage of FIG. 3. At this time, the gate voltage of the first switch can decrease rapidly. Further, when the gate voltage of the first switch is less than or equal to the third threshold value, the first switch enters a stage where EMI and voltage stress can be generated significantly, as shown in the sixth stage of FIG. 3. At this time, in order to reduce the voltage stress and EMI generation of the first switch while not causing too much impact on the turn-off speed of the first switch, the controller can reduce the decrease rate of the gate voltage of the first switch, thereby effectively reducing the voltage stress and EMI generation.

[0105] For example, when the turn-off time of the first switch comes, the controller provides the first driving current to the gate of the first switch to control the gate voltage of the first switch to decrease rapidly. Further, in order to reduce the voltage stress and EMI that can be caused by the rapid decrease of the gate voltage, when the controller detects that the gate voltage of the first switch is less than or equal to the third threshold value through the second voltage detection terminal, the controller provides the fourth driving current to the gate of the first switch to reduce the decrease rate of the gate voltage of the first switch. That is, the decrease rate of the gate voltage of the first switch under the fourth driving current is smaller than the decrease rate (i.e., the first decrease rate) under the first driving current. At this time, since the controller controls the decrease rate of the gate voltage of the first switch to decrease, the voltage stress and EMI generation can be reduced while not affecting the turn-off speed of the first switch.

[0106] For the convenience of understanding the implementation process of the power conversion device for controlling the turn-off of the first switch by the controller, the following content is exemplified in combination with FIG. 6, which is another waveform diagram of the first switch provided by an embodiment of the present application. In FIG. 6, the PWM shown in FIG. 6 is a signal for controlling the turn-off of the first switch, Vg is the gate voltage of the first switch, Ig is the driving current provided by the controller to the gate of the first switch (such as the first driving current, the second driving current, the third driving current or the fourth driving current), and Vq is the voltage difference between the first electrode and the second electrode of the first switch.

[0107] It can be understood that, as shown in FIG. 6, when the T0 moment comes, the controller receives the PWM signal for controlling the first switch tube to be low, which represents that the turn-off moment of the first switch tube comes. At this time, the first switch tube switches from the on state to the off state, and the controller can provide the first driving current Isk0 to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to start to drop from the maximum value Vsk0. The first driving current Isk0 is a pull-down current relative to the gate of the first switch tube, that is, the first driving current Isk0 can pull down the gate voltage of the first switch tube. If combined with FIG. 4, the flow direction of the first driving current Isk0 is opposite to that of the driving current Ig in FIG. 4. In addition, since 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 T1 moment comes, the controller detects that the gate voltage of the first switch tube drops to the third threshold value Vsk1 through the second voltage detection end, which represents that the first switch tube enters a stage in which EMI and voltage stress can be generated. In order to reduce the generation of voltage stress and EMI without greatly affecting the turn-off speed of the first switch tube, the controller provides the fourth driving current Isk2 to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to slowly drop from Vsk1. The fourth driving current Isk2 is a pull-down current relative to the gate of the first switch tube, that is, the fourth driving current Isk2 can pull down the gate voltage of the first switch tube. If combined with FIG. 4, the flow direction of the fourth driving current Isk2 is opposite to that of the driving current Ig in FIG. 4. In addition, the fourth driving current Isk2 can be smaller than the first driving current Isk1, so that the drop rate of the gate voltage Vg of the first switch tube after the T1 moment is smaller than that before the T1 moment. At the same time, the voltage difference Vq between the first electrode and the second electrode of the first switch tube continues to increase.

[0109] When the T2 moment comes, the controller detects 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 through the first voltage detection end, which represents that the first switch tube enters a stage in which EMI and voltage stress can be generated greatly. In order to reduce the generation of voltage stress and EMI, the controller provides the second driving current Isp to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to start to rise from Vsk2. The second driving 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 starts to rise, the gate voltage of the first switch tube does not rise to be greater than or equal to the turn-on threshold value, so the first switch tube is still in an incomplete off state, and the voltage difference Vq between the first electrode and the second electrode of the first switch tube continues 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 continues to increase, the gate voltage of the first switch tube is raised due to the second driving current Isp provided by the controller to the gate of the first switch tube, which in turn prevents the voltage difference Vq from suddenly increasing during the turn-off process of the first switch tube, thereby reducing the voltage stress of the first switch tube and the generation of EMI.

[0111] When T3 arrives, the controller detects 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 through the first voltage detection terminal, indicating that the first switch tube enters a stage where even fast turn-off will not cause a substantial 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 driving 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. The third driving 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 action of the third driving current Isk3, the gate voltage of the first switch tube rapidly decreases. When T4 arrives, the gate voltage of the first switch tube decreases to the turn-off threshold value 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 working voltage Vbus of the bus.

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

[0114] In some possible embodiments, the controller can determine the size of the first driving current based on the size of the driving current provided to the gate of the first switch tube when the controller controls the first switch tube to turn off at a target turn-off speed.

[0115] As can be seen from the above, when the first switch tube is to be turned off, the first switch tube enters a stage in which the first switch tube can be turned off quickly without causing EMI and voltage stress. At this time, the controller can provide a first driving current to the first switch tube, so that the gate voltage of the first switch tube is quickly reduced. It can be seen that the first driving current can quickly drive the gate voltage of the first switch tube to be reduced. Therefore, in order to determine the size of the first driving current, the controller can use a plurality of candidate driving currents as the gate driving current of the first switch tube to drive the first switch tube to perform a plurality of turn-off tests. Further, when the turn-off speed of the first switch tube reaches a target turn-off speed in the plurality of turn-off tests, the controller uses one of the candidate driving currents as the first driving current.

[0116] It should be noted that the target turn-off speed refers to the minimum value of the turn-off speed of the first switch tube in order to meet the requirement of the power conversion device on the switching speed. That is, when the turn-off speed of the first switch tube is greater than or equal to the target turn-off speed, the requirement of the power conversion device on the switching speed can be met, and the first switch tube will not be damaged. On the contrary, when the turn-off speed of the first switch tube is less than the target turn-off speed, the requirement of the power conversion device on the switching speed is not met.

[0117] For example, it is assumed that the controller uses Isk10, Isk11 and Isk12 as the plurality of candidate driving currents. Further, when the controller provides the candidate driving current Isk10 to the gate of the first switch tube to drive the first switch tube to be turned off, the turn-off speed of the first switch tube is v0. When the controller provides the candidate driving current Isk11 to the gate of the first switch tube to drive the first switch tube to be turned off, the turn-off speed of the first switch tube is v1. When the controller provides the candidate driving current Isk12 to the gate of the first switch tube to drive the first switch tube to be turned off, the turn-off speed of the first switch tube is v2. At this time, it is assumed that the target turn-off speed of the first switch tube is va, and v0 < v1 < va < v2. It can be seen that when the controller provides the candidate driving current Isk12 to the gate of the first switch tube to drive the first switch tube to be turned off, the turn-off speed of the first switch tube is greater than the turn-off speed when the first switch tube is driven to be turned off by the other candidate driving currents, and is greater than or equal to the target turn-off speed va of the first switch tube. At the same time, when the controller drives the first switch tube to be turned off by 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 possible implementation, the controller can determine the size of the third driving current based on the size of the driving current provided to the gate of the first switch tube when the first switch tube is controlled to be turned off at the target turn-off speed.

[0119] It should be noted that the specific implementation of the controller determining the size of the third driving current can refer to the specific implementation of determining the size of the first driving current, which will not be repeated here. In addition, the size of the first driving current and the third driving current can be the same or different, which will not be limited here.

[0120] In some possible implementation, the controller can determine the size of the second driving current based on the following content.

[0121] It should be noted that the size 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, and then the voltage stress generated by the first switch tube will be larger. Conversely, 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 then the voltage stress generated by the first switch tube will be relatively small.

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

[0123] Wherein, 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 rises, and from the above content, it can be known that the voltage stress generated by the first switch tube will be larger. Conversely, 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 rises, and from the above content, it can be known that the voltage stress generated by the first switch tube will be smaller.

[0124] To this end, in the embodiments of the present application, the controller can determine the size of the second driving current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. Further, when the voltage stress generated by the first switch tube is relatively large, it indicates that the load connected to the power conversion device is heavy, and the controller can increase the output second driving current to make the gate voltage of the first switch tube rise 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, it indicates that the load connected to the power conversion device is light, and the controller can reduce the output second driving current to make the gate voltage of the first switch tube rise slower, thereby reducing the voltage stress generated by the first switch tube while appropriately increasing the turn-off speed of the first switch tube.

[0125] In some possible embodiments, the controller can detect the first electrode voltage of the first switch tube through the first voltage detection terminal after the turn-off moment of the first switch tube arrives and the controller provides the first driving current to the gate of the first switch tube, to obtain the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube.

[0126] For example, as shown in FIG. 5, after the moment T0 arrives, 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 Vh1 between the first electrode and the second electrode of the first switch tube, and obtains the voltage difference Vh2 between the first electrode and the second electrode of the first switch tube after a preset time range. The controller can obtain the rate of change dv / dt of the voltage difference between the first electrode and the second electrode of the first switch tube in the preset time range, that is, T is the above-mentioned preset time range.

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

[0128] Exemplarily, as shown in FIG. 6, after the time T1 arrives, the controller provides the fourth driving current Isk2 to the gate of the first switch tube. Meanwhile, the controller detects the first electrode voltage of the first switch tube through the first voltage detection terminal, so as 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 Vh1 between the first electrode and the second electrode of the first switch tube, and obtains the voltage difference Vh2 between the first electrode and the second electrode of the first switch tube after a preset time range. The controller can obtain the voltage difference variation rate dv / dt of the first electrode and the second electrode of the first switch tube in the preset time range, that is, T.

[0129] It can be understood that the controller can also obtain the voltage difference variation rate of the first electrode and the second electrode of the first switch tube through other manners, which will not be exemplified one by one in the embodiments of the present application.

[0130] In some possible implementation manners, after obtaining the voltage difference variation rate of the first electrode and the second electrode of the first switch tube, the controller can determine that the driving current value corresponding to the voltage difference variation rate is the size of the second driving current based on a preset relationship table. The preset relationship table includes the driving current values corresponding to different values of the voltage difference variation rate one by one. The preset relationship table can be obtained based on multiple turn-off tests or practical summaries of the first switch tube, which is not limited in the embodiments of the present application.

[0131] The power conversion device provided by the embodiments of the present application can increase the size of the second driving current when the voltage difference variation rate of the first electrode and the second electrode of the first switch tube is relatively large, so as to effectively reduce the voltage stress generated by the first switch tube. The controller can reduce the size of the second driving current when the voltage difference variation rate of the first electrode and the second electrode of the first switch tube is relatively small, so as to appropriately increase 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 the voltage difference variation rate a1 of the first electrode and the second electrode of the first switch tube, the controller can determine the size of the second driving current as Isp1 based on the voltage difference variation rate a1. When the controller obtains the voltage difference variation rate a2 of the first electrode and the second electrode of the first switch tube, and a2>a1, the controller can determine the size of the second driving current as Isp2 based on the voltage difference variation rate a2, and Isp2>Isp1.

[0133] In some possible embodiments, the controller can determine the size of the second driving current based on the rate of change of the voltage difference between the first electrode and the second electrode of the first switch, and based on the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference.

[0134] It should be noted that, according to the above description, the size of the voltage stress generated by the first switch is related to the rate of change of the voltage difference between the first electrode and the second electrode of the first switch, and the size of the change of the voltage difference between the first electrode and the second electrode of the first switch can also be represented by the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference.

[0135] In the formula, the longer the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference, the slower the change of the voltage difference between the first electrode and the second electrode of the first switch, and the smaller the voltage stress generated by the first switch. Conversely, the shorter the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference, the faster the change of the voltage difference between the first electrode and the second electrode of the first switch, and the greater the voltage stress generated by the first switch.

[0136] Therefore, in the embodiments of the present application, the controller can determine the size of the second driving current based on the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference. Further, when the voltage stress generated by the first switch is relatively large, it indicates that the load connected to the power conversion device is heavy, and the controller can increase the output second driving current to make the gate voltage of the first switch rise faster, thereby effectively reducing the voltage stress generated by the first switch. When the voltage stress generated by the first switch is relatively small, it indicates that the load connected to the power conversion device is light, and the controller can reduce the output second driving current to make the gate voltage of the first switch rise slower, thereby reducing the voltage stress generated by the first switch while appropriately increasing the turn-off speed of the first switch.

[0137] In some possible embodiments, the controller can detect the first electrode voltage of the first switch through the first voltage detection terminal to obtain the time length for the voltage difference between the first electrode and the second electrode of the first switch to increase from the first voltage difference to the second voltage difference after the controller provides the first driving current to the gate of the first switch at the turn-off moment of the first switch.

[0138] Exemplarily, as shown in FIG. 5, after the arrival of the time T0, the controller provides the first driving current Isk1 to the gate of the first switch tube. Meanwhile, 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, 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 possible implementation manners, after the controller provides the fourth driving 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 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.

[0140] Exemplarily, as shown in FIG. 6, after the arrival of the time T1, the controller provides the fourth driving current Isk2 to the gate of the first switch tube. Meanwhile, 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, 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 can be understood 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 through other manners, which are not exemplified one by one in the embodiments of the present application.

[0142] It should be noted that the controller can be preconfigured with specific values of the first voltage difference and the second voltage difference. In actual application, the specific values of the first voltage difference and the second voltage difference can be calculated according to the working voltage of the bus and the target off time of the first switch tube. Specifically, the controller needs to obtain the time length T before the complete off of the first switch tube, that is, before the voltage across the first switch tube reaches the working voltage of the bus, and thus the first voltage difference and the second voltage difference are less than 5V of the working voltage of the bus. Meanwhile, since the controller can obtain the time length T as early as possible in the off process of the first switch tube, so as to timely adjust the gate voltage of the first switch tube, the first voltage difference and the second voltage difference preconfigured in the controller are usually positively correlated with the target off time of the first switch tube.

[0143] For example, assuming that the working voltage of the bus is 5V, the target off duration of the first switch tube is 100ms, i.e., the off duration of the first switch tube is 100ms. When the controller needs to obtain the time length T in the first 40ms of the off duration of the first switch tube, the controller can pre-set the second voltage difference as 5V*(40ms / 100ms)=2V, and the first voltage difference can be 1V. It can be understood that after the off time 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 during which the voltage difference between the first electrode and the second electrode of the first switch tube increases from 1V to 2V, i.e., the above-mentioned time length T. The above is only an example and does not constitute a limitation on the embodiments of the present application.

[0144] In some possible embodiments, after obtaining the time length during which 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 controller can determine, based on a preset relationship table, that the driving current value corresponding to the time length is the size of the second driving current. The preset relationship table includes driving current values corresponding to different time lengths in a one-to-one manner. The preset relationship table can be obtained based on multiple off tests or practical summaries of the first switch tube, and the embodiments of the present application are not limited thereto.

[0145] The power conversion device provided by the embodiments of the present application can improve the size of the second driving current when the time length during which 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 small, thereby effectively reducing the voltage stress generated by the first switch tube. The controller can reduce the size of the second driving current when the time length during which 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 large, which can reduce the voltage stress generated by the first switch tube while appropriately improving the off speed of the first switch tube.

[0146] For example, when the controller obtains the time length during which 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 equal to t1, the controller can determine the size of the second driving current as Isp1 based on the time length t1. When the controller obtains the time length during which 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 equal to t2, and t2>t1, the controller can determine the size of the second driving current as Isp2 based on the time length t2, and Isp2<Isp1.

[0147] In some possible embodiments, 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 first threshold value, the controller can first provide a second driving current to the gate of the first switch tube, and the value of the second driving 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 while providing the second driving current to the gate of the first switch tube, and adjust the value of the second driving current based on the rate of change of the voltage difference.

[0148] Specifically, the controller can detect the voltage of the first electrode of the first switch tube through the first voltage detection terminal while providing the second driving current to the gate of the first switch tube, to obtain the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube. The specific embodiments in which the controller obtains the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube can refer to the above description, and will not be repeated here.

[0149] In some possible embodiments, further, the controller can adjust the second driving current provided to the gate of the first switch tube in a decreasing manner based on the value of the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, until the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube obtained by the controller reaches a target value, and the adjustment of the second driving current is completed. The target value of the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube can be adjusted according to the requirements of actual application scenarios, and will not be limited in the embodiments of the present application.

[0150] In some possible embodiments, after obtaining the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the controller can also determine, based on a preset relationship table, a driving current value corresponding to the rate of change of the voltage difference as a target value of the adjustment of the second driving current. The preset relationship table includes driving current values corresponding to different values of the rate of change of the voltage difference in a one-to-one manner. The preset relationship table can be obtained based on multiple turn-off tests or practical summaries of the first switch tube, and will not be limited in the embodiments of the present application.

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

[0152] In some possible embodiments, 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 first threshold value, the controller can first provide a second driving current to the gate of the first switch tube, and the value of the second driving current can be preset. Further, the controller can obtain the length of time during which 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 when the second driving current is provided to the gate of the first switch tube, and adjust the size of the second driving current based on the length of time.

[0153] Specifically, when the controller provides the second driving 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 length of time during which 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 specific embodiments in which the controller obtains the length of time during which 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 can refer to the foregoing content, and will not be described herein again.

[0154] In some possible embodiments, further, after the controller obtains the length of time during which 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 controller can adjust the second driving current provided to the gate of the first switch tube in a decreasing manner based on the size of the length of time, until the length of time during which 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 reaches a target value, and the adjustment of the second driving current is completed. The target value of the length of time during which 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 can be adjusted according to the requirements of an actual application scenario, and the embodiments of the present application do not limit this.

[0155] In some possible embodiments, after the controller obtains the length of time during which 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 controller can also determine, based on a preset relationship table, a driving current value corresponding to the length of time as a target value of the adjustment of the second driving current. The preset relationship table includes driving current values corresponding to different lengths of time in a one-to-one manner. The preset relationship table can be obtained based on multiple turn-off tests of the first switch tube or practical summaries, and the embodiments of the present application do not limit this.

[0156] It can be understood that, after the controller determines the target value of the adjustment of the second driving current, the controller can adjust the second driving current provided to the gate of the first switch tube, so that the value of the second driving current can be equal to the target value, and the adjustment of the second driving current is completed.

[0157] In some possible embodiments, the controller can determine the size of the time threshold based on the following.

[0158] It should be noted that the length of time for which the controller provides the second driving current to the gate of the first switch tube is related to the voltage stress generated by the first switch tube. The greater the length of time for which the controller provides the second driving current to the gate of the first switch tube, that is, the greater the time threshold, the more the voltage stress generated by the first switch tube can be reduced. Therefore, the controller can determine the size of the time threshold based on the size of the voltage stress that the first switch tube can generate.

[0159] As can be seen from the above, the size 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 can be represented by the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube.

[0160] It can be understood 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 length of time for which the controller needs to provide the second driving current to the gate of the first switch tube, that is, the greater the time threshold. Conversely, 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 length of time for which the controller needs to provide the second driving current to the gate of the first switch tube, that is, the smaller the time threshold.

[0161] Further, when the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube is relatively large, the controller can increase the time threshold to increase the length of time for which the second driving current is output to the gate of the first switch tube, thereby effectively reducing the voltage stress generated by the first switch tube. When the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube is relatively small, the controller can reduce the time threshold to shorten the length of time for which the second driving current is output to the gate of the first switch tube, thereby reducing the voltage stress generated by the first switch tube while appropriately increasing the turn-off speed of the first switch tube.

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

[0163] In some possible embodiments, after obtaining the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube, the controller can determine a time length value corresponding to the rate of change of the voltage difference as the size of the time threshold based on a preset relationship table. The preset relationship table includes time length values corresponding to different values of the rate of change of the voltage difference in a one-to-one manner. The preset relationship table can be obtained based on multiple turn-off tests of the first switch tube or practical summaries, which are not limited in the embodiments of the present application.

[0164] In some possible embodiments, in addition to determining the size of the 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, the controller can also determine the size of the 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.

[0165] It should be noted that, according to the above content, the size 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 size of the rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube can also be represented by 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.

[0166] In the above embodiments, 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 smaller the voltage stress generated by the first switch tube, and the shorter the time length for the controller to provide the second driving current to the gate of the first switch tube, that is, the smaller the time threshold. Conversely, 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 greater the voltage stress generated by the first switch tube, and the longer the time length for the controller to provide the second driving current to the gate of the first switch tube, that is, the greater the time threshold.

[0167] Further, 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 can increase the time threshold to increase the time length for outputting the second driving current to the gate of the first switch tube, thereby effectively reducing the voltage stress generated by the first switch tube. When the time length is relatively long, the controller can reduce the time threshold to shorten the time length for outputting the second driving current to the gate of the first switch tube, thereby reducing the voltage stress generated by the first switch tube while appropriately increasing the turn-off speed of the first switch tube.

[0168] It should be noted that the specific implementation of the controller obtaining the length of time 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 refer to the above description, and the embodiments of the present application will not be repeated here.

[0169] In some possible embodiments, after obtaining the length of time 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, based on a preset relationship table, a threshold value corresponding to the length of time as the size of the time threshold. The preset relationship table includes threshold values corresponding to different lengths of time in a one-to-one manner. The preset relationship table can be obtained based on multiple turn-off tests of the first switch tube or practical summary, and the embodiments of the present application are not limited thereto.

[0170] In some possible embodiments, the following describes the principle of the controller controlling the turn-on of the first switch tube.

[0171] As can be seen from the above description, the first switch tube has different working characteristics in different stages of the turn-on process. Therefore, in order to reduce the turn-on loss of the first switch tube while reducing the current stress and EMI, the power conversion device provided by the embodiments of the present application can segmentally control the turn-on process of the first switch tube according to the working characteristics of the first switch tube in different stages of the turn-on process, that is, different control modes are performed on the first switch tube in different stages, so that the turn-on speed, current stress and EMI of the first switch tube can be reduced at the same time.

[0172] Specifically, when the controller receives a PWM signal for controlling the first switch tube as high, 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 driving current to the gate electrode of the first switch tube to control the gate voltage of the first switch tube to rise rapidly.

[0173] It can be understood that when the turn-on time of the first switch tube arrives, the first switch tube is in a stage where rapid turn-on does not cause EMI and current stress, as shown in the first stage and the fourth stage in FIG. 3. Therefore, the controller can control the gate voltage of the first switch tube to rise rapidly by providing the fifth driving current to the gate electrode of the first switch tube when the turn-on time of the first switch tube arrives, so as to accelerate the turn-on speed of the first switch tube and reduce the turn-on loss of the first switch tube.

[0174] It can be understood that the power conversion device can provide different driving currents to the first switch tube in different stages through the controller, so that the gate voltage of the first switch tube has different rising rates in different stages. For example, in the second stage and the third stage shown in FIG. 3, the controller is in a stage in which current stress and EMI can be generated. Therefore, the controller can reduce the rising rate of the gate voltage of the first switch tube by controlling the turn-on speed of the first switch tube in the second stage and the third stage, thereby reducing the current stress and EMI.

[0175] In some possible embodiments, after the controller provides the fifth driving current to the gate of the first switch tube to control the rapid rising of the gate voltage of the first switch tube, the controller can further obtain the gate voltage of the first switch tube through the second voltage detection terminal, and provide a sixth driving current to the gate of the first switch tube to control the first switch tube to reduce the rising rate of the gate voltage when the gate voltage of the first switch tube is greater than or equal to a fourth threshold value. Wherein, the controller controlling the first switch tube to reduce the rising rate of the gate voltage means that the rising rate of the gate voltage of the first switch tube is less than the first rising rate, and the first rising rate is the rising 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 value, the rapid turn-off of the first switch tube will not cause the generation of current stress and EMI, as shown in the first stage in FIG. 3. When the gate voltage of the first switch tube is greater than or equal to the fourth threshold value, it indicates that the first switch tube enters a stage in which EMI and current stress can be generated, as shown in the second stage and the third stage in FIG. 3. Therefore, in order to reduce the generation of current stress and EMI of the first switch tube, the controller can control the first switch tube to reduce the rising rate of the gate voltage, so as to effectively reduce the generation of current stress and EMI.

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

[0178] In some possible embodiments, as shown in FIG. 3, in the second and third phases, the first switch tube is turned on at a faster speed, which directly leads to the generation of EMI and current stress, while in the fourth phase, the first switch tube is turned on at a faster speed, which does not lead to the generation of EMI and current stress. Therefore, in order to speed up the turn-on of the first switch tube to reduce the turn-on loss of the first switch tube while reducing the generation of current stress and EMI, after the controller provides the sixth driving 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 value, the controller provides the seventh driving current to the gate of the first switch tube, so as to control the gate voltage of the first switch tube to rise rapidly until the gate voltage of the first switch tube is greater than or equal to the above-mentioned turn-on threshold value, i.e., 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 rise, which can make the voltage difference between the first electrode and the second electrode decrease. Before the voltage difference between the first electrode and the second electrode of the first switch tube decreases to be less than or equal to the fifth threshold value, the first switch tube is in a phase in which EMI and current stress can be generated greatly, as shown in the second and third phases of FIG. 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 value, the fast turn-off of the first switch tube also does not lead to the generation of current stress and EMI, as shown in the fourth phase of FIG. 3.

[0180] In order to make the first switch tube be able to turn on rapidly and reduce the turn-on 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 less than or equal to the fifth threshold value, the controller provides the seventh driving current to the gate of the first switch tube, so as to control the gate voltage of the first switch tube to rise rapidly until the gate voltage of the first switch tube is greater than or equal to the turn-on threshold value, i.e., the first switch tube is turned on.

[0181] In order to facilitate understanding of the implementation process of the power conversion device in controlling the turn-on of the first switch tube by the controller, the following content is exemplified in combination with FIG. 7, which is another waveform diagram of the first switch tube provided by the embodiments of the present application. In FIG. 7, the PWM is a signal for controlling the turn-on 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), and Vq is the voltage difference between the first electrode and the second electrode of the first switch tube.

[0182] It can be understood that, as shown in FIG. 7, at the moment T0, the controller receives the PWM signal for controlling the first switch tube to be high, indicating that the moment of turning on the first switch tube comes. At this moment, the first switch tube switches from the off state to the on state, and the controller can provide the fifth driving current Iscl to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to start rising from the minimum value Vsc0. The fifth driving current Iscl is a current flowing to the gate of the first switch tube, that is, the fifth driving current Iscl can pull up the gate voltage of the first switch tube. If combined with FIG. 4, the flow direction of the fifth driving current Iscl is consistent with the flow direction of the driving current Ig in FIG. 4. In addition, since the first switch tube starts to turn on, the voltage difference Vq between the first electrode and the second electrode of the first switch tube starts to decrease.

[0183] At the moment T1, the controller detects that the gate voltage Vg of the first switch tube rises to the fourth threshold value Vsc1 through the first voltage detection end, indicating that the first switch tube enters a stage in which EMI and current stress can be generated greatly. In order to reduce the generation of current stress and EMI, the controller provides the sixth driving current Isc2 to the gate of the first switch tube through the current control end to reduce the rising speed of the gate voltage Vg of the first switch tube. The sixth driving current Isc2 is a pull-up current with respect to the gate of the first switch tube. Since the first switch tube is still in an incomplete on state, the voltage difference Vq between the first electrode and the second electrode of the first switch tube continues to decrease.

[0184] At the moment T2, the controller detects that the voltage difference Vq between the first electrode and the second electrode of the first switch tube decreases to the fifth threshold value Vf through the first voltage detection end. At this moment, the first switch tube enters a stage in which EMI and current stress will not be generated greatly even if the first switch tube is turned on quickly. In order to speed up the turn-on speed of the first switch tube and reduce the turn-on loss of the first switch tube, the controller provides the seventh driving current Isc3 to the gate of the first switch tube through the current control end to control the gate voltage Vg of the first switch tube to start rising quickly from Vsc2. The seventh driving current Isc3 is a pull-up current with respect to the gate of the first switch tube.

[0185] It can be understood that, under the pull-up action of the seventh driving current Isc3, the gate voltage of the first switch tube rises quickly, and when the gate voltage rises to the turn-on threshold value Vsc3, the first switch tube is completely turned on. At this moment, 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 method of the fifth drive current, the sixth drive current and the seventh drive current, and the fourth threshold and the fifth threshold are not described here. In addition, the conduction process of the second switch tube connected in series with the first switch tube in the power conversion device can refer to the specific implementation method of the first switch tube, and the embodiments of the present application will not be described here.

[0187] In some possible embodiments, the controller can determine the size of the fifth drive current based on the size of the drive current provided to the gate of the first switch tube when the first switch tube is controlled to turn on at a target turn-on speed.

[0188] From the above, it can be seen that when the turn-on time of the first switch tube arrives, the first switch tube enters a stage in which it can be quickly turned on 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 is quickly raised. As can be seen, the fifth drive current functions to quickly drive the gate voltage of the first switch tube to rise. Therefore, in order to determine the size of the fifth drive current, the controller can use a plurality of candidate drive currents as the gate drive current of the first switch tube to drive the first switch tube to conduct a plurality of turn-on tests. Further, the controller can use a candidate drive current used by the controller when the turn-on speed of the first switch tube reaches the target turn-on speed in the plurality of turn-on tests as the fifth drive current.

[0189] It should be noted that the target turn-on speed refers to the minimum value of the turn-on speed of the first switch tube in order to meet the requirement of the power conversion device for the switching speed. That is, when the turn-on speed of the first switch tube is greater than or equal to the target turn-on speed, the requirement of the power conversion device for the switching speed can be met, and the first switch tube will not be damaged. On the contrary, when the turn-on speed of the first switch tube is less than the target turn-on speed, the requirement of the power conversion device for the switching speed is not met.

[0190] For example, assume that the controller takes IsclO, Iscll and Iscl2 as the above-mentioned multiple candidate drive currents. Further, the controller obtains the turn-on speed of the first switch tube as v0 when providing the candidate drive current IsclO to the gate of the first switch tube to drive the first switch tube to turn on. The controller obtains the turn-on speed of the first switch tube as vl when providing the candidate drive current Iscll to the gate of the first switch tube to drive the first switch tube to turn on. The controller obtains the turn-off speed of the first switch tube as v2 when providing the candidate drive current Iscl2 to the gate of the first switch tube to drive the first switch tube to turn on. At this time, assume that the target turn-on speed of the first switch tube is vb, and v0 < vl < vb < v2. Thus, it can be seen that the turn-on speed of the first switch tube when the controller provides the candidate drive current Iscl2 to the gate of the first switch tube to drive the first switch tube to turn on is greater than the turn-on speed when the first switch tube is driven to turn off by other candidate drive currents, and is greater than or equal to the target turn-on speed vb of the first switch tube. Meanwhile, the controller does not cause damage to the first switch tube when driving the first switch tube to turn on by the candidate drive current, and thus the controller can take the candidate drive current Iscl2 as the fifth drive current of the first switch tube.

[0191] In some possible implementation manners, the controller can determine the size of the seventh drive current based on the size of the drive current provided to the gate of the first switch tube when the first switch tube is controlled to turn on at the target turn-off 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 of determining the size of the fifth drive current, which will not be described herein again. In addition, the size of the fifth drive current and the size of the seventh drive current can be the same or different, which is not limited in the embodiment of the application.

[0193] In some possible implementation manners, the controller can determine the size of the fifth threshold based on the following content.

[0194] It can be known from the above content that the power conversion device in the embodiment of the application controls the first switch tube to turn on by the controller, aiming to reduce the turn-on loss of the first switch tube, and to reduce the generated current stress and EMI in the turn-on process. To this end, the power conversion device can take multiple voltage thresholds as candidate voltage thresholds to detect the generated current stress and EMI of the first switch tube when the candidate voltage threshold is applied in the turn-on process of the first switch tube, and to determine the optimal voltage threshold as the fifth threshold.

[0195] Specifically, since the voltage across the first switch tube in the conduction process can be equal to the working voltage of the bus at most, the fifth threshold value is in the range between the working voltage of the bus and zero. Therefore, the controller can obtain multiple voltage threshold values as candidate voltage threshold values based on the working voltage of the bus. For example, the controller can take 1 / N to (N-1) / N of the working voltage of the bus as the multiple voltage threshold values, where N is a positive integer greater than 1.

[0196] It can be understood that the controller can take one voltage threshold value as a candidate voltage threshold value, and obtain the voltage difference between the first electrode and the second electrode of the first switch tube through the first voltage detection terminal in the case of providing the 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 value, 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 multiple voltage threshold values, that is, takes each voltage threshold value as a candidate voltage threshold value, and controls the first switch tube to perform multiple full conduction tests respectively.

[0197] Meanwhile, in order to compare the current stress and EMI generated by the first switch tube in multiple conduction processes, the controller can obtain the current amplitude flowing through the first electrode and the second electrode of the first switch tube in each conduction process. The change of the current amplitude can be used to represent the current stress and EMI generated by the first switch tube. For example, the current amplitude of the first switch tube can be represented by Is as shown in FIG. 6. The smaller the peak value of the current amplitude Is of the first switch tube, the less the current stress and EMI generated by the first switch tube.

[0198] Therefore, the controller can obtain the current stress and EMI generated by the first switch tube under different voltage threshold values based on the current amplitudes corresponding to the multiple voltage threshold values obtained in the multiple full conduction tests. Further, the controller can take the voltage threshold value corresponding to the least current stress and EMI generated by the first switch tube as the fifth threshold value.

[0199] It should be noted that the value of the first threshold value and the second threshold value can also refer to the specific embodiments of the fifth threshold value, and the embodiments of the present application will not be repeated here.

[0200] In the embodiment of the present application, when the turn-on moment of the first switch tube arrives, the controller controls the gate voltage of the first switch tube to rise, and when the gate voltage of the first switch tube is greater than or equal to the fourth threshold value, the rising rate of the gate voltage of the first switch tube is reduced, which can effectively reduce the current stress and the generation of EMI. Further, when the voltage difference across the first switch tube is less than or equal to the fifth threshold value, the controller controls the rising rate of the gate voltage of the first switch tube to increase until the first switch tube is fully turned on, which can improve the turn-on speed of the first switch tube while reducing the current stress and the generation of EMI, and thus the turn-on loss can be reduced.

[0201] Please refer to FIG. 8, which is a flowchart of the control method of the power conversion device provided by the present application. The control method of the power conversion device provided by the embodiment of the present application is applicable to the controller shown in FIGS. 1 to 7. Specifically, the control method of the power conversion device can include the following steps:

[0202] S101, when the turn-off moment of the first switch tube arrives, a first drive current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to drop, 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 value, a second drive current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to rise.

[0203] It should be noted that 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, and when the voltage difference across the first switch tube, i.e., the voltage difference between the first electrode and the second electrode, reaches the first threshold value, 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 rise, which can effectively reduce the voltage stress and the generation of EMI.

[0204] The specific implementation of S101 can refer to the implementation of the controller in FIGS. 1 to 7, which will not be described here in detail.

[0205] S102, 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 value while the second drive current is provided to the gate of the first switch tube, or when the length of time during which the second drive current is provided to the gate of the first switch tube is greater than or equal to the time threshold value, a third drive current is provided to the gate of the first switch tube to control the gate voltage of the first switch tube to drop until the first switch tube is turned off.

[0206] It should be noted that when the voltage difference across the power conversion device at the first switch tube, i.e., the voltage difference between the first electrode and the second electrode, is greater than or equal to the second threshold value, or when the length of time 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 value, the third drive current is provided to the gate of the first switch tube by the controller to control the gate voltage of the first switch tube to change from rising to falling until the first switch tube is completely turned off, which can improve the turn-off speed of the first switch tube while reducing voltage stress and EMI generation, and thus can reduce turn-off loss.

[0207] The specific implementation of S102 can refer to the implementation of the controller in FIGS. 1-7, which will not be described here.

[0208] In an optional embodiment, the method further includes: obtaining the gate voltage of the first switch tube when the first drive current is provided to the gate of the first switch tube, and providing a fourth drive current to the gate of the first switch tube to control the falling rate of the gate voltage of the first switch tube to be less than the first falling rate when the gate voltage of the first switch tube is less than or equal to a third threshold value, the first falling rate being the falling rate of the gate voltage of the first switch tube when the first drive current is provided to the gate of the first switch tube.

[0209] It can be understood that after the first drive current is provided to the gate of the first switch tube, the controller can obtain the gate voltage of the first switch tube, and control the falling rate of the gate voltage of the first switch tube to decrease when the gate voltage of the first switch tube is less than or equal to the third threshold value, which can further improve the turn-off speed of the first switch tube while reducing voltage stress and EMI generation, and effectively reduce turn-off loss.

[0210] In an optional embodiment, the method includes: obtaining the current size of the first drive current and the current size of the third drive current based on the gate drive current for controlling the first switch tube to turn off at the target turn-off speed.

[0211] It can be understood that the power conversion device can obtain the current size of the first drive current and the current size of the third drive current based on the gate drive current corresponding to the target turn-off speed by the controller. 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 quickly fall, which can further improve the turn-off speed of the first switch tube and effectively reduce turn-off loss.

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

[0213] It can be understood that when the controller drives the first switch tube based on the second driving current, the gate voltage of the first switch tube can be raised to reduce voltage stress and EMI generation. The controller obtains the current size of the second driving current based on the voltage difference change rate of 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 comprises: after providing the first driving current to the gate of the first switch tube, detecting a time length for the voltage difference of the first electrode and the second electrode of the first switch tube to increase from a first voltage difference to a second voltage difference, and obtaining the size of the second driving current based on the detected time length for the voltage difference of 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.

[0215] It can be understood that when the controller drives the first switch tube based on the second driving current, the gate voltage of the first switch tube can be raised to reduce voltage stress and EMI generation. The controller obtains the current size of the second driving current based on the time length for the voltage difference of 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.

[0216] In an optional embodiment, the method comprises: in the case of providing the second driving current to the gate of the first switch tube, adjusting the current size of the second driving current based on the voltage difference change rate of the first electrode and the second electrode of the first switch tube.

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

[0218] In an optional embodiment, the method comprises: in the case of providing the second driving current to the gate of the first switch tube, adjusting the size of the second driving current based on the time length for the voltage difference of the first electrode and the second electrode of the first switch 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 working voltage of the bus.

[0219] It can be understood that the controller can adjust the current size of the second driving current based on the length of time 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 the first switch tube is provided with the second driving current, thereby effectively reducing voltage stress and EMI generation, being easy to implement and being capable of being adjusted in real time.

[0220] In an optional embodiment, the method comprises: detecting a rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube after the first driving current is provided to the gate of the first switch tube, and obtaining 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.

[0221] It can be understood that the controller can determine the value of the 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 the first switch tube is provided with the first driving current, which is easy to implement and has high accuracy.

[0222] In an optional embodiment, the method comprises: detecting the length of time 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 the first driving current is provided to the gate of the first switch tube, and obtaining the time threshold based on the detected length of time 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.

[0223] It can be understood that the controller can determine the value of the time threshold based on the length of time 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 the first switch tube is provided with the first driving current, which is easy to implement and has high accuracy.

[0224] In an optional embodiment, the method further comprises: when the turn-on time of the first switch tube arrives, providing a fifth driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to rise, and when the gate voltage of the first switch tube is greater than or equal to a fourth threshold value, providing a sixth driving current to the gate of the first switch tube to control the rising rate of the gate voltage of the first switch tube to be less than a first rising rate, the first rising rate being the rising 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 voltage difference between the first electrode and the second electrode of the first switch tube is less than or equal to a fifth threshold value in the case that the sixth driving current is provided to the gate of the first switch tube, providing a seventh driving current to the gate of the first switch tube to control the rising rate of the gate voltage of the first switch tube to be greater than a second rising rate until the first switch tube is turned on, wherein the second rising rate is the rising rate of the gate voltage of the first switch tube when the sixth driving current is provided to the gate of the first switch tube, and the fifth threshold value is less than the working voltage of the bus.

[0225] It can be understood that, by the controller, the rising of the gate voltage of the first switch tube is controlled when the turn-on time of the first switch tube arrives, and the rising rate of the gate voltage of the first switch tube is controlled to decrease when the gate voltage of the first switch tube is greater than or equal to the fourth threshold value, so that the current stress and the generation of EMI can be effectively reduced. Further, by the controller, the rising rate of the gate voltage of the first switch tube is controlled to increase 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 value until the first switch tube is completely turned on, so that the turn-on speed of the first switch tube can be improved while the current stress and the generation of EMI are reduced, and thus the turn-on loss can be reduced.

[0226] In an optional embodiment, the method comprises: obtaining the current size of the fifth driving current and the current size of the seventh driving current based on the gate driving current when the first switch tube is controlled to be turned on at the target turn-on speed.

[0227] It can be understood that the controller can obtain the current size of the fifth driving current and the current size of the seventh driving current based on the gate driving current corresponding to the target turn-on speed. Further, when the first switch tube is driven by the controller based on the fifth driving current or the seventh driving current, the gate voltage of the first switch tube can be quickly raised, so that the turn-on speed of the first switch tube can be further improved, and the turn-on loss can be effectively reduced.

[0228] In an optional embodiment, the method further comprises: obtaining a plurality of voltage thresholds based on the operating voltage of the bus, the voltage threshold being less than the operating voltage of the bus; in the case that the sixth drive current is provided to the gate electrode of the first switch tube, traversing the plurality of voltage thresholds to take each voltage threshold as a candidate voltage threshold, and in the case that 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 the seventh drive current to the gate electrode of the first switch tube to control the gate voltage of the first switch tube to rise until the first switch tube is turned on; obtaining the current amplitude of the first electrode and the second electrode of the first switch tube corresponding to the candidate voltage threshold in the process of turning on the first switch tube to obtain the current amplitude of the first electrode and the second electrode corresponding to each voltage threshold; and determining the fifth threshold from the plurality of voltage thresholds based on the current amplitude of the first electrode and the second electrode corresponding to each voltage threshold.

[0229] It can be understood that the controller can take one voltage threshold as a candidate voltage threshold, and in the case that the sixth drive current is provided to the gate electrode of the first switch tube, the voltage difference between the first electrode and the second electrode of the first switch tube is obtained through the first voltage detection terminal. 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 electrode of the first switch tube until the first switch tube is completely turned on. Further, the controller traverses the plurality of voltage thresholds, that is, takes each voltage threshold as a candidate voltage threshold, and controls the first switch tube to perform a plurality of complete turn-on tests respectively.

[0230] Meanwhile, in each turn-on 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 represent 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 plurality of voltage thresholds obtained in the plurality of complete turn-on tests respectively. Further, the controller can take the voltage threshold corresponding to the least 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 embodiments of the present application also provide a switch driving chip, which comprises the controller in the power conversion device. The switch driving chip can be connected with the first switch tube and the second switch tube respectively, and the first switch tube and the second switch tube are turned on or turned off. The specific implementation mode of the switch driving chip can refer to the implementation mode of the controller in the foregoing FIGS. 1 to 8, and the embodiments of the present application will not be described here again.

[0232] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, various software modules in accordance with embodiments of the present application are stored in a memory such as a computer memory or disk storage for use by, or in connection with, the software on the computer system. The software can provide for programs to be transferred to another computer readable medium (e.g., a removable medium, or a medium conveyed through a computer network) for use in a different system.

[0233] The present application is described in reference to the flow diagrams and / or block diagrams of the methods, apparatus (systems) and computer program products according to this application. It will be understood that each block of the flow diagrams and / or block diagrams, and combinations of blocks in the flow diagrams and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flow diagrams and / or block diagrams block or blocks.

[0234] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flow diagrams and / or block diagrams block or blocks.

[0235] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flow diagrams and / or block diagrams block or blocks.

[0236] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A power conversion device, characterized by, The power conversion device comprises a controller, a first switch tube and a second switch tube connected in series; a gate of the first switch tube is connected to the controller, a first electrode of the first switch tube is connected to the second switch tube, a second electrode of the first switch tube is grounded or connected to a bus, and the controller is configured to: when a turn-off time of the first switch tube arrives, providing a first driving current to the gate of the first switch tube to control a gate voltage of the first switch tube to drop, and when a 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 driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to rise; when the voltage difference between the first electrode and the second electrode of the first switch tube is greater than or equal to a second threshold, or when a length of time for which the second driving current is provided to the gate of the first switch tube is greater than or equal to a time threshold, providing a third driving current to the gate of the first switch tube to control the gate voltage of the first switch tube to drop until the first switch tube is turned off, under the condition that the second driving current is provided to the gate of the first switch tube.

2. The power conversion device of claim 1, wherein, The controller is configured to: under the condition that the first driving current is provided to the gate of the first switch tube, acquiring the gate voltage of the first switch tube, and when the gate voltage of the first switch tube is less than or equal to a third threshold, providing a fourth driving current to the gate of the first switch tube to control a falling rate of the gate voltage of the first switch tube to be less than a first falling rate, the first falling rate being a falling rate of the gate voltage of the first switch tube when the first driving current is provided to the gate of the first switch tube.

3. A power conversion device according to claim 1 or 2, characterized in that The controller is configured to: based on a gate driving current used for controlling the first switch tube to be turned off at a target turn-off speed, obtaining a current size of the first driving current and a current size of the third driving current.

4. A power conversion device according to any one of claims 1-3, characterized in that, The controller is configured to: after the first driving current is provided to the gate of the first switch tube, detecting a voltage difference changing rate of the first electrode and the second electrode of the first switch tube, and obtaining the size of the second driving current based on the detected voltage difference changing rate of the first electrode and the second electrode of the first switch tube.

5. A power conversion device according to any one of claims 1-3, characterized in that, The controller is configured to: after the first driving current is provided to the gate of the first switch tube, detecting a length of time for which a voltage difference of the first electrode and the second electrode of the first switch tube increases from a first voltage difference to a second voltage difference, and obtaining the size of the second driving current based on the detected length of time for which the voltage difference of the first electrode and the second electrode of the first switch tube increases from the first voltage difference to the second voltage difference; wherein the first voltage difference and the second voltage difference are less than an operating voltage of the bus.

6. A power conversion device according to any one of claims 1-3, characterized in that The controller is configured to: under the condition that the second driving current is provided to the gate of the first switch tube, adjusting the current size of the second driving current based on a voltage difference changing rate of the first electrode and the second electrode of the first switch tube.

7. A power conversion device according to any one of claims 1-3, characterized in that The controller is configured to: The second driving current is adjusted in size based on a length of time for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from a first voltage difference to a second voltage difference, in a case where the second driving current is provided to the gate of the first switch tube. The first voltage difference and the second voltage difference are less than an operating voltage of the bus.

8. A power conversion device according to any one of claims 1-7, characterized in that The controller is configured to: detect a rate of change of the voltage difference between the first electrode and the second electrode of the first switch tube after the first driving current is provided to the gate 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.

9. A power conversion device according to any one of claims 1-7, characterized in that The controller is configured to: detect a length of time for the voltage difference between the first electrode and the second electrode of the first switch tube to increase from a first voltage difference to a second voltage difference after the first driving current is provided to the gate of the first switch tube, and obtain the time threshold based on the detected length of time 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 first voltage difference and the second voltage difference are less than an operating voltage of the bus.

10. A power conversion device according to any one of claims 1-9, characterized in that, The controller is configured to: provide a fifth driving current to the gate of the first switch tube when a turn-on time of the first switch tube arrives, to control a rate of rise of the gate voltage of the first switch tube, and provide a sixth driving current to the gate of the first switch tube when the gate voltage of the first switch tube is greater than or equal to a fourth threshold value, to control the rate of rise of the gate voltage of the first switch tube to be less than a first rate of rise, the first rate of rise being a rate of rise of the gate voltage of the first switch tube when the fifth driving current is provided to the gate of the first switch tube; provide a seventh driving current 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 a fifth threshold value, in a case where the sixth driving current is provided to the gate of the first switch tube, to control the rate of rise of the gate voltage of the first switch tube to be greater than a second rate of rise until the first switch tube turns on, the second rate of rise being a rate of rise of the gate voltage of the first switch tube when the sixth driving current is provided to the gate of the first switch tube, and the fifth threshold value being less than the operating voltage of the bus.

11. The power conversion device of claim 10, wherein, The controller is configured to: obtain the current size of the fifth driving current and the current size of the seventh driving current based on the gate driving current used to control the first switch tube to turn on at a target turn-on speed.

12. A control method of a power conversion apparatus, characterized by, The power conversion device includes 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 includes: a first driving current is provided to the gate of the first switch tube when the turn-off moment of the first switch tube comes, to control the gate voltage of the first switch tube to drop, and a second driving 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 a first threshold, to control the gate voltage of the first switch tube to rise; a third driving 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 a second threshold, or the time length for which the second driving current is provided to the gate of the first switch tube is greater than or equal to a time threshold, to control the gate voltage of the first switch tube to drop until the first switch tube turns off, in the case that the second driving current is provided to the gate of the first switch tube.

13. The control method according to claim 12, characterized by, The method further comprises: a fifth driving current is provided to the gate of the first switch tube when the turn-on moment of the first switch tube comes, to control the gate voltage of the first switch tube to rise, and a sixth driving current is provided to the gate of the first switch tube when the gate voltage of the first switch tube is greater than or equal to a fourth threshold, to control the rising rate of the gate voltage of the first switch tube to be less than a first rising rate, the first rising rate being the rising rate of the gate voltage of the first switch tube in the case that the fifth driving current is provided to the gate of the first switch tube; a seventh driving 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 a fifth threshold, to control the rising rate of the gate voltage of the first switch tube to be greater than a second rising rate until the first switch tube turns on, in the case that the sixth driving current is provided to the gate of the first switch tube, the second rising rate being the rising rate of the gate voltage of the first switch tube in the case that the sixth driving current is provided to the gate of the first switch tube, and the fifth threshold being less than the working voltage of the bus.

14. The control method according to claim 13, characterized by, The method further comprises: a plurality of voltage thresholds are obtained based on the working voltage of the bus, the voltage thresholds being less than the working voltage of the bus; each of the voltage thresholds is taken as a candidate voltage threshold in the case that the sixth driving current is provided to the gate of the first switch tube, and a seventh driving 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 candidate voltage threshold, to control the gate voltage of the first switch tube to rise until the first switch tube turns on; the current amplitude of the first electrode and the second electrode of the first switch tube corresponding to the candidate voltage threshold in the conduction process of the first switch tube is obtained, to obtain the current amplitude of the first electrode and the second electrode corresponding to each of the voltage thresholds; the fifth threshold is determined from the plurality of voltage thresholds based on the current amplitude of the first electrode and the second electrode corresponding to each of the voltage thresholds.

15. A switch driving chip, characterized by comprising: The switch driving chip comprises the controller according to any one of claims 1 to 11, and is connected with the first switch tube and the second switch tube. The switch driving chip is used for driving the first switch tube to be turned on or turned off, and is used for driving the second switch tube to be turned on or turned off.

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