CN-122026701-A - Silicon carbide power switch driving circuit

CN122026701ACN 122026701 ACN122026701 ACN 122026701ACN-122026701-A

Abstract

The invention provides a silicon carbide power switch driving circuit, which relates to the technical field of power electronic driving and comprises a pulse generating module, an isolation transformer and a driving output module, wherein the pulse generating module converts input direct-current voltage into alternating pulse voltage with dead time and outputs the alternating pulse voltage to a primary side winding of the isolation transformer, the driving output module comprises a charging loop, an active discharging loop and a discharging resistor assembly, the active discharging loop comprises a normally-on switching tube, a control end of the normally-on switching tube is connected with one winding section of a secondary side winding, and a discharging passage bypassing the secondary side winding is provided for a gate-source capacitor by conduction in the dead time. The discharge resistor assembly comprises a first discharge resistor and a second discharge resistor which are arranged in series and are respectively positioned outside and inside the active bleeder circuit. The invention effectively accelerates the discharge falling edge, solves the contradiction between the discharge speed and the oscillation inhibition, and has simple structure and low cost.

Inventors

GONG ZHIPENG
MENG SONGLIN
ZHAO ZHENXING
PENG ZISHUN
YANG YACHAO
DAI YUXING

Assignees

湖南工程学院

Dates

Publication Date: 20260512
Application Date: 20260204

Claims (10)

1. The silicon carbide power switch driving circuit is characterized by comprising a pulse generating module, an isolation transformer and a driving output module; The pulse generation module is used for converting the input direct-current voltage into alternating pulse voltage with dead time and outputting the alternating pulse voltage to a primary winding of the isolation transformer; The secondary winding of the isolation transformer is provided with at least two taps, and the secondary winding is divided into at least three winding sections; The driving output module comprises a charging loop, an active discharging loop and a discharging resistor component, wherein the charging loop is used for charging a grid source capacitor of the silicon carbide power switch respectively at a forward phase and a reverse phase of the alternating pulse voltage, the active discharging loop comprises a normally-on switching tube, a control end of the normally-on switching tube is connected with one section of winding sections of the secondary winding, the normally-on switching tube is conducted in the dead time, a discharging path bypassing the secondary winding is provided for the grid source capacitor, the discharging resistor component comprises a first discharging resistor and a second discharging resistor which are arranged in series, the first discharging resistor is arranged outside the active discharging loop, and the second discharging resistor is arranged inside the active discharging loop.
2. The silicon carbide power switch driving circuit according to claim 1, wherein the secondary winding comprises a first winding section, a second winding section and a third winding section, a first tap is arranged between the first winding section and the second winding section, a second tap is arranged between the second winding section and the third winding section, the end part of the first winding section is the same-name end of the secondary winding, and the end part of the third winding section is the different-name end of the secondary winding.
3. The silicon carbide power switch driving circuit according to claim 2, wherein the charging circuit comprises a positive-voltage charging branch and a negative-voltage charging branch, the positive-voltage charging branch comprises a grid resistor and a first diode, an anode of the first diode is connected with the same-name end through the grid resistor, a cathode of the first diode is connected with a grid of the silicon carbide power switch, the second tap is connected with a source of the silicon carbide power switch, the negative-voltage charging branch comprises the first discharging resistor, the second discharging resistor and a first normally-on switch tube, and the second winding section is connected with a grid source capacitor of the silicon carbide power switch through the first normally-on switch tube, the first discharging resistor and the second discharging resistor which are conducted.
4. A silicon carbide power switch driving circuit according to claim 3, wherein the active bleeder circuit further comprises a second diode and a second normally-on switch tube, an anode of the second diode is connected with a first end of the second discharging resistor, a cathode of the second diode is connected with a first end of the second normally-on switch tube, a second end of the second normally-on switch tube is connected with a source electrode of the silicon carbide power switch, a second end of the second discharging resistor is connected with a grid electrode of the silicon carbide power switch, and a control end of the second normally-on switch tube is connected with a different-name end of the third winding section.
5. A silicon carbide power switch driving circuit according to claim 4, wherein the control terminal of the first normally-on switching tube is connected to the second tap, the first terminal of the first normally-on switching tube is connected to the first discharge resistor, and the second terminal of the first normally-on switching tube is connected to the first tap.
6. A silicon carbide power switch driving circuit according to any of claims 3-5, wherein the normally-on switching tube is a depletion N-channel MOSFET.
7. The silicon carbide power switch driving circuit according to claim 1, wherein the pulse generation module comprises a PWM signal generator and a full-bridge push-pull circuit, the full-bridge push-pull circuit comprises a first bridge arm and a second bridge arm, the first bridge arm is formed by connecting a first upper pipe and a first lower pipe in series, the second bridge arm is formed by connecting a second upper pipe and a second lower pipe in series, the first upper pipe and the second upper pipe are enhanced N-channel MOSFETs, the first lower pipe and the second lower pipe are enhanced P-channel MOSFETs, the PWM signal generator outputs two paths of complementary PWM signals to drive the first bridge arm and the second bridge arm respectively, and the middle point of the first bridge arm and the middle point of the second bridge arm are connected with two ends of the primary winding respectively.
8. The silicon carbide power switch driving circuit according to claim 1, wherein the isolation transformer comprises two groups of secondary windings, and the same-name ends of the two groups of secondary windings are opposite in position and are respectively used for driving the upper bridge arm silicon carbide power switch and the lower bridge arm silicon carbide power switch.
9. A silicon carbide power switch driving circuit according to claim 4, wherein the primary winding has a number of turns n1, the first winding has a number of turns n21, the second winding has a number of turns n22, and the third winding has a number of turns n23, and the forward driving voltage V 1 and the reverse driving voltage V 2 satisfy: Wherein V in is the input dc voltage.
10. A silicon carbide power switch driving circuit according to claim 9, wherein the bleeder circuit resistor is a resistor in dead time Less than the reverse charging loop resistance A bleed-off loop resistance within the dead time The method comprises the following steps: Reverse charging loop resistor The method comprises the following steps: Wherein, the For the on-resistance of the normally-on switching tube, R fH1 is the resistance of the first discharge resistor, R fH2 is the resistance of the second discharge resistor, and R2 is larger than R1.

Description

Silicon carbide power switch driving circuit Technical Field The invention relates to the technical field of power electronic driving, in particular to a silicon carbide power switch driving circuit. Background The existing silicon carbide power device driving scheme mainly comprises an application specific integrated driving chip, a discrete component driving circuit, an active driving circuit, an isolation transformer driving circuit and the like. The special integrated chip has high integration level, convenient use, fixed driving capability, poor adaptability in high-power multi-tube parallel connection occasions and higher cost. The discrete component driving circuit has flexible design, but the number of components is large, the PCB layout is complex, and parasitic parameters are easy to cause ringing and overshoot during high-frequency operation. The active driving circuit can optimize the switching performance by monitoring the switching transient state and dynamically adjusting the driving parameters in real time, but the active driving circuit needs control signals with different multipath phases, and has great design and debugging difficulty. The isolation transformer driving circuit realizes electrical isolation by using the transformer and completes voltage transformation, and can output the required voltage amplitude by only adjusting the number of turns of the winding, so that the isolation transformer driving circuit has a simple structure and controllable cost, and is an ideal technical route at present. The key point of realizing asymmetric driving by adopting an isolation transformer is that the same winding of the transformer outputs symmetric voltages at different phases, and the positive and negative driving voltages required by the silicon carbide device are not equal in amplitude. To solve this contradiction, the existing scheme generally sets taps on the secondary winding of the transformer, divides the winding into two parts, and outputs voltages with different magnitudes by using the turns ratios of different winding sections. Different charging loops can be respectively selected in the on-off stage by matching with the on-off of the diode and the MOSFET, so that asymmetric driving voltage output is realized. However, the prior isolation transformer driving scheme generally faces a significant problem in that the transformer windings participate in the current loop of all working phases, and the windings inevitably have leakage inductance, and the leakage inductance and the gate-source parasitic capacitance of the silicon carbide device form a series RLC resonant circuit. In the discharge phase after the forward voltage, leakage inductance limits the rate of change of the discharge current, resulting in an extended capacitor discharge time and a slow falling edge of the driving signal. If the discharge resistance is reduced to increase the discharge speed, the loop may enter an underdamped state to induce voltage oscillation, and if the resistance is increased to suppress the oscillation, the discharge speed is further reduced. Because the discharging loop and the reverse charging loop share the same path, the two stages are mutually influenced when the resistance is regulated, and the independent optimization cannot be realized. The contradiction makes the prior proposal difficult to simultaneously meet the double requirements of rapid discharge and oscillation inhibition, and seriously affects the switching performance of the silicon carbide power device. The Chinese patent document CN108063542A discloses a simple, reliable and low-cost silicon carbide power switch device driving circuit, and discloses a technical scheme for realizing asymmetric voltage output by adopting a full-bridge push-pull circuit matched with a tapped isolation transformer and utilizing self-driving of a depletion type MOSFET, which has the technical effects of single power supply, simple circuit, low cost and capability of outputting +15V/-5V asymmetric driving voltage, but still has the problems that a transformer winding participates in all current loops to limit discharge speed, and a common loop of discharge and reverse charge can not give consideration to rapid discharge and oscillation inhibition. The Chinese patent document CN108683327B discloses a silicon carbide MOSFET driving circuit, and discloses a technical scheme of adopting independent three-power supply to cooperate with an auxiliary discharging loop of a P-channel MOS tube and clamping protection of a voltage-stabilizing diode, which has the technical effects of accelerating turn-off speed, preventing overvoltage breakdown of a grid electrode and reducing bridge arm crosstalk, but still has the problems that multiple paths of isolation power supplies are required to increase system complexity and cost, and oscillation suppression depends on passive clamping and belongs to post-remediation rather than source management. Disclosure of Inve