Overcurrent protection circuit

Abstract

The embodiment of the invention discloses an overcurrent protection circuit, and a switch module and a sampling control module are arranged between a driving module and a first transistor; when the sampling control module samples that the voltage of the third end of the first transistor reaches a first preset voltage, the switch module is controlled to disconnect the discharge path of the charge-discharge module, so that the current output by the driving module cannot pass through the switch module and is output to the charge-discharge module, and the charge-discharge module is charged; when the voltage of the charging and discharging module reaches a second preset voltage, the driving module outputs a turn-off control signal to the first end of the first transistor to turn off the first transistor, so that the first transistor is turned off by reasonably setting the magnitude of the first preset voltage and the magnitude of the second preset voltage; when a certain difference exists between the current flowing through the first transistor and the overcurrent protection point of the first transistor, the first transistor is turned off, so that the first transistor can be protected,and the current flowing through the first transistor is prevented from being damaged due to overlarge current.

Description

technical field [0001] Embodiments of the present invention relate to the technical field of power device protection, in particular to an overcurrent protection circuit. Background technique [0002] When the IGBT / MOS tube is driven, the drive requires isolation, and a driver chip is usually used to drive it, for example, a 1ED020I12FA2 driver chip is used to drive the IGBT / MOS tube. However, when driving IGBT / MOS transistors, the problem of device damage usually occurs due to overcurrent, so the overcurrent protection of the driving circuit is particularly important. [0003] In the prior art, the desaturation detection method is usually used to realize the overcurrent protection of the driving circuit. The main principle is: taking the 1ED020I12FA2 driving chip as an example, using the Desat pin of the driving chip to detect the collector and emitter of the IGBT / MOS tube The voltage drop is used to protect the IGBT / MOS tube and prevent the IGBT / MOS tube from being damaged...

AI Technical Summary

Problems solved by technology

However, this method has some disadvantages: when the Desat pin of the driver chip detects that the voltage between the collector and the emitter rises rapidly, the current of the driver tube will generally reach about 4 times the nominal current, and the driver tube will be turned off at this time. It will cause a large turn-off peak at both ends of the collector and emitter, so an additional circuit is required to suppress the voltage spike, and the loss of the drive tube is also large, which will affect the service life of the drive tube, and even directly cause the drive tube damage

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