Gate drive circuit and drive method of silicon carbide device

Abstract

The invention discloses a gate drive circuit and a gate drive method of a silicon carbide device, which can suppress current overshoot in a conduction process, effectively improve the reliability of acircuit system and reduce the conduction loss of the silicon carbide device. The gate drive circuit comprises a drive module, a voltage division module, an integration module and a differential module. The driving module generates an original driving signal according to the pulse width modulation signal; the voltage division module performs voltage division processing on the original driving signal to obtain a first voltage signal and a second voltage signal, sends the first voltage signal to the integration module, and sends the second voltage signal to the differential module; the integration module performs delay processing of preset time on the first voltage signal; and the difference module performs difference operation on the first voltage signal and the second voltage signal afterdelay processing to obtain an output signal, so that the output signal is the second voltage signal before the preset time, and the voltage value of the output signal is smaller than the voltage valueof the second voltage signal after the preset time.

Description

technical field [0001] The invention relates to the field of circuits, in particular to a gate drive circuit and a drive method of a silicon carbide device. Background technique [0002] Traditional silicon (Si) material power devices have a narrow bandgap and low blocking voltage. It is difficult to meet the requirements of the new generation of power systems in terms of energy consumption, operating temperature and switching frequency, which has become a bottleneck in the development of power electronics technology. Silicon carbide (SiC) is a new type of semiconductor material with wide bandgap and high breakdown voltage. Its bandgap width is about 3 times that of Si material, and its breakdown voltage is more than 10 times that of Si material. Compared with traditional Si-based power devices, SiC MOSFET has the advantages of higher blocking voltage, lower on-state resistance, good thermal conductivity, high-speed breaking capability, etc. It is used in electric vehicle dr...

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Problems solved by technology

[0003] Although SiC MOSFET has many advantages in application, because of its very high switching speed, SiC MOSFET is very sensitive to the packaging, wiring, stray parasitic inductance of the line and the device's own node capacitance, mainly reflected in Under the application of high voltage, high power and high switching speed, it is easy to generate high voltage change rate (dv / dt) and current change rate (di / dt) when SiC MOSFET is turned on and off, resulting in current overshoot and voltage overshoot. Problems such as shock and long-term switching oscillation will significantly increase device loss, seriously affect system efficiency, electromagnetic compatibility and other performance, and reduce system reliability

[0004] In order to protect SiC devices, measures are usually taken to suppress overcurrent and overvoltage. Although the existing method of variable drive resistance can delay the rise and fall time of the current, it increases the switching delay and Miller plateau time, making the SiC MOSFET generate larger The switching loss affects the efficiency of the converter; although the existing method of adding a snubber circuit can effectively reduce the turn-off overvoltage of the SiC MOSFET, it cannot reduce the on-through current, and the snubber circuit needs to use high-voltage devices, which will not reduce the The loss of the circuit will instead bring greater additional loss; although the existing closed-loop active drive circuit can accurately control the waveform of the switching process, suppress voltage and current peaks and reduce switching losses, the implementation is more complicated and requires High-speed and high-bandwidth operational amplifiers, D / A conversion chips, FPGAs and other devices are expensive to implement and have long control delays; the existing multi-drive resistor control method switches between the delay stage, the current rising stage, and the Miller platform stage The resistance controls the switching speed, and each parallel branch contains a bidirectional switch. Since the switching process of SiCMOSFET is short, it is necessary to add a faster driving circuit for the bidirectional switch. Generally, CPLD / FPGA is used to realize multi-driving resistance control, which increases the cost of the system. and complexity

[0005] Therefore, none of the existing technologies can simultaneously solve the problems of current overshoot, system reliability and conduction loss

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