IGBT active overcurrent protection device and protection method

Abstract

The invention discloses an IGBT active overcurrent protection device and protection method. The IGBT active overcurrent protection device comprises the following steps: a direct-current boosting module is used for increasing the driving voltage of an IGBT to a preset voltage value; the Vce desaturation detection module detects the collector voltage of the IGBT, and the detection voltage of the Vce desaturation detection module positively changes along with the collector voltage; the sampling comparison module obtains the detection voltage of the Vce desaturation detection module, and sends an overcurrent signal to the programmable control chip when the detection voltage is greater than a preset voltage threshold value; the programmable control chip controls the soft turn-off module to turn off the IGBT according to the overcurrent signal. By improving an active excitation voltage value, an over-current protection voltage action threshold value is increased, after a programmable chip detects an out-of-limit signal exceeding a voltage threshold during over-current, a soft turn-off circuit is started, reliable over-current protection is carried out on an IGBT, an RC circuit does not need to delay to prevent interference and maloperation, and the protection response time is shortened.

Description

Technical field [0001] Technical Field The present invention relates to an electronic power control, particularly to an active IGBT overcurrent protection method and apparatus. Background technique [0002] IGBT widely used in high-power power electronic converter system, IGBT often work at a high pressure, high current. The working curve IGBT safe zone, overcurrent, overvoltage and effect injection engine failure is the leading cause IGBT. Wherein the short-circuit overcurrent into soft through hard-short leg and a short side of the load, soft shorts may be protected by a current detecting circuit, and a hard short-circuit inductance small, short-circuit current rises sharply, if not promptly and accurately detect the fault and protection, can easily lead to permanent damage to the IGBT, greatly reduce the reliability of the system, especially for large impact failure, high operation and maintenance costs of the high-power direct current transmission power transformation device....

AI Technical Summary

Problems solved by technology

Actually, it takes time to drop from the bus voltage to the desaturation detection threshold voltage, according to figure 1 Active diode Vce desaturation detection circuit, in the actual measurement circuit, there is a large amplitude interference voltage in the waveform of Vce detection voltage test point 2, such as figure 2 As shown, in order to avoid this kind of interference, it usually needs to be detected after a delay of more than 9us. For example, the Chinese patent authorization number is: CN205545179U, an IGBT over-current detection circuit and over-current protection circuit. For the opening process, the RC delay is increased. The timing is adjustable so that misoperations during the turn-on process will not occur, but the response time is almost equivalent to the maximum withstand time of the IGBT. Once the IGBT is turned on, there is a risk of being burned, which greatly reduces the reliability.

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