CN-122026878-A - Driving circuit

CN122026878ACN 122026878 ACN122026878 ACN 122026878ACN-122026878-A

Abstract

The invention discloses a driving circuit which comprises a driving unit, at least two voltage equalizing units and at least one discharging unit, wherein the driving unit is used for being connected with a power device to drive the power device to be turned on or turned off, a first end of each voltage equalizing unit is connected with a source electrode of the power device, a second end of each voltage equalizing unit is connected with a drain electrode of the same power device, any discharging unit is connected between third ends of two adjacent voltage equalizing units, the voltage equalizing units are used for equalizing the power device in the process of turning off the power device, the discharging unit is used for providing a discharging loop for the next voltage equalizing unit to the last voltage equalizing unit in the process of turning on the power device, and the last power device correspondingly connected with the last voltage equalizing unit is on one side, close to a ground end, of the next power device correspondingly connected with the next voltage equalizing unit. The voltage-sharing unbalance degree among the power devices is improved, the voltage-sharing precision is improved, and the switching loss of the power devices is reduced.

Inventors

LI XUEBAO
Lv Xuzhe
LI WENYUAN
YAN HAO
PAN YAN
ZHAO ZHIBIN
JIN RUI
CUI XIANG

Assignees

北京怀柔实验室

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (10)

1. A driving circuit for driving at least two power devices connected in series, the driving circuit comprising: the driving unit is used for being connected with the power device to drive the power device to be turned on or turned off; the power device comprises at least two voltage equalizing units and at least one discharging unit, wherein a first end of each voltage equalizing unit is connected with a source electrode of one power device, a second end of each voltage equalizing unit is connected with a drain electrode of the same power device, any discharging unit is connected between third ends of two adjacent voltage equalizing units, the voltage equalizing units are used for equalizing voltage of the power devices in the process of switching off the power devices, the discharging units are used for providing a discharging loop for the next voltage equalizing unit to the last voltage equalizing unit in the process of switching on the power devices, and the last power device correspondingly connected with the last voltage equalizing unit is on one side, close to the ground end, of the next power device correspondingly connected with the next voltage equalizing unit.
2. The driving circuit according to claim 1, wherein the discharge unit comprises a first unidirectional conduction device, the positive electrode of the first unidirectional conduction device is connected with the third end of the previous voltage equalizing unit, and the negative electrode of the first unidirectional conduction device is connected with the third end of the next voltage equalizing unit.
3. The drive circuit of claim 2, wherein the discharge unit further comprises a first resistor, the first resistor and the first unidirectional conductive device being connected in series between third terminals of adjacent two of the voltage equalizing units.
4. The drive circuit according to claim 1, wherein each voltage equalizing unit includes a first capacitor, a second resistor, and a second unidirectional conductive device; The first end of the first capacitor is connected with the drain electrode of the power device, the second end of the first capacitor is connected with the first end of the second resistor and the positive electrode of the second unidirectional conduction device, and then is connected with one end of the discharge unit, and the second end of the second resistor and the negative electrode of the second unidirectional conduction device are connected with the source electrode of the power device.
5. The drive circuit of claim 1, wherein the drive circuit is configured to drive a plurality of the power devices connected in series, the drive circuit further comprising: And the first adjusting unit to the last adjusting unit are respectively connected between the grid electrode and the drain electrode of the second power device to the last power device, and each adjusting unit is used for inhibiting the rising rate of the drain-source voltage of the correspondingly connected power device in the process of turning off the power device.
6. The driving circuit according to claim 5, wherein the adjusting unit includes a second capacitor, and the capacitance values of the second capacitors in the first to last adjusting units gradually decrease.
7. The drive circuit according to any one of claims 1-6, wherein the drive unit comprises a drive power supply, at least one third unidirectional conducting device, at least two current limiting modules, at least two static voltage balancing modules, at least one power storage module, and at least two voltage stabilizing modules; The power device comprises a power device, a current limiting module, a driving power supply, a first end and a second end, wherein the first end of each current limiting module is connected with a grid electrode of one power device respectively, and the current limiting module is used for limiting the current of the grid electrode of the power device; Each third unidirectional conduction device is connected between the second ends of two adjacent current limiting modules, and the positive electrode of each third unidirectional conduction device is connected with the second end of the last current limiting module; The first ends of the first to last electric quantity storage modules are connected with the negative output end of the driving power supply, and the second ends of the first to last electric quantity storage modules are respectively connected with the second ends of the second to last current limiting modules; the electric quantity storage module is used for providing a discharge loop for the power device which is correspondingly connected in the process of switching off the power device; The second ends of two adjacent current limiting modules in the at least two current limiting modules are respectively connected with one static voltage equalizing module, the source electrode and the drain electrode of the last power device are connected with the other static voltage equalizing module, and the static voltage equalizing modules are used for carrying out static voltage equalizing on the power device; Each voltage stabilizing module is connected between the grid electrode and the source electrode of one power device and used for stabilizing the voltage between the grid electrode and the source electrode of the power device.
8. The drive circuit of claim 7, wherein the static voltage balancing module comprises a third resistor, the power storage module comprises a third capacitor, and the current limiting module comprises a fourth resistor; The first end of each fourth resistor is connected with the grid electrode of one power device, one third resistor is connected between the second ends of every two adjacent fourth resistors, and the other third resistor is connected between the source electrode and the drain electrode of the last power device; The first end of each third capacitor is connected with the negative output end of the driving power supply, and the second end of each third capacitor is connected with the second ends of the second resistor to the last resistor.
9. The drive circuit of claim 7, wherein the voltage regulator module comprises a first voltage regulator diode and a second voltage regulator diode; The anode of the first zener diode is connected with the anode of the second zener diode, the cathode of the first zener diode is connected with the grid electrode of the power device which is correspondingly connected, and the cathode of the second zener diode is connected with the source electrode of the power device which is correspondingly connected.
10. The drive circuit of claim 1, wherein the drive unit further comprises at least one fourth capacitor; Each fourth capacitor is respectively connected between the grid electrode and the source electrode of the second to last power devices.

Description

Driving circuit Technical Field The embodiment of the invention relates to the technical field of power electronics, in particular to a driving circuit. Background In recent years, with the in-depth application of a novel power electronic system in the scenes of photovoltaic inverter, electric traffic, high-temperature industrial converter, high-voltage direct current transmission and the like, a wide-bandgap semiconductor device represented by silicon carbide (SiC) gradually replaces a traditional silicon-based device, and becomes an important core of a high-frequency, high-voltage and high-temperature power module. The voltage class transition of the high-voltage application scene requires that the power module must develop towards the high-voltage high-current direction, and the power module has two ways for realizing the high-voltage high-current, the first way is to use the high-voltage chip for parallel connection, but the method has the problems of poor economy, difficult commercialization of the high-voltage chip at present, low chip yield, easy degradation of the gate oxide layer and the like. The second approach is to use low voltage chips in series. However, in the practical application of low-voltage chip serial connection, the power module faces a serious challenge of insufficient dynamic-static voltage equalizing precision under the high-voltage and high-current scene. When the low-voltage chips are connected in series, the power module can adopt a passive buffer circuit for equalizing voltage, and the problems that 1, overvoltage is easy to generate mainly exist at the moment. 2. The dynamic and static pressure equalizing precision is low. 3. The switching loss is large. Disclosure of Invention The invention provides a driving circuit which can improve the voltage equalizing effect between power devices connected in series and improve the reliability of the power devices. In a first aspect, an embodiment of the present invention provides a driving circuit for driving at least two power devices connected in series, the driving circuit including: the driving unit is used for being connected with the power device to drive the power device to be turned on or turned off; the power device comprises at least two voltage equalizing units and at least one discharging unit, wherein a first end of each voltage equalizing unit is connected with a source electrode of one power device, a second end of each voltage equalizing unit is connected with a drain electrode of the same power device, any discharging unit is connected between third ends of two adjacent voltage equalizing units, the voltage equalizing units are used for equalizing voltage of the power devices in the process of switching off the power devices, the discharging units are used for providing a discharging loop for the next voltage equalizing unit to the last voltage equalizing unit in the process of switching on the power devices, and the last power device correspondingly connected with the last voltage equalizing unit is on one side, close to the ground end, of the next power device correspondingly connected with the next voltage equalizing unit. Optionally, the discharging unit comprises a first unidirectional conduction device, wherein the positive electrode of the first unidirectional conduction device is connected with the third end of the previous voltage equalizing unit, and the negative electrode of the first unidirectional conduction device is connected with the third end of the next voltage equalizing unit. Optionally, the discharging unit further comprises a first resistor, and the first resistor and the first unidirectional conduction device are connected in series between third ends of two adjacent voltage equalizing units. Optionally, each voltage equalizing unit comprises a first capacitor, a second resistor and a second unidirectional conduction device; The first end of the first capacitor is connected with the drain electrode of the power device, the second end of the first capacitor is connected with the first end of the second resistor and the positive electrode of the second unidirectional conduction device, and then is connected with one end of the discharge unit, and the second end of the second resistor and the negative electrode of the second unidirectional conduction device are connected with the source electrode of the power device. Optionally, the driving circuit is configured to drive a plurality of power devices connected in series, and the driving circuit further includes: And the first adjusting unit to the last adjusting unit are respectively connected between the grid electrode and the drain electrode of the second power device to the last power device, and each adjusting unit is used for inhibiting the rising rate of the drain-source voltage of the correspondingly connected power device in the process of turning off the power device. Optionally, the adjusting unit comprises a second capacitor, and the capa