Overcurrent protection device of variable-frequence governor

Abstract

The invention discloses an overcurrent protection device of a variable-frequence governor, which comprises an inverter circuit, wherein a drive circuit is connected onto the inverter circuit; a sampling circuit, a conditioning circuit, a comparison circuit and a singlechip microcomputer are serially connected onto the inverter circuit sequentially; the sampling circuit is used for collecting voltage signals output by three phases of the inverter circuit; the outputs of the conditioning circuit is a first conditioning output signal UA and a second conditioning output signal UB; the compassion circuit is used for respectively inputting the signals to reverse input ends of two comparators correspondingly, respectively inputting reference voltage obtained by a serial voltage division circuit to non-inverting input ends of the two comparators, and connecting output signals of the two comparators with the singlechip microcomputer; and the singlechip microcomputer is connected with the drive circuit and is used for closing the output of the inverter circuit through the drive circuit when one or two of the first conditioning output signal UA and the second conditioning output signal UB is larger than the reference voltage. Overcurrent protection points are set by hardware, so that higher accuracy and reliability are realized.

Description

technical field [0001] The invention belongs to the technical field of frequency converters, and in particular relates to an overcurrent protection device for frequency converters. Background technique [0002] The frequency conversion speed controller is a power control device that converts the power frequency power supply to another frequency by using the on-off function of the power semiconductor device, and can realize functions such as speed regulation of the AC motor. Excessive current will cause damage to the internal devices of the frequency converter, and the output current of the frequency converter exceeds the maximum current that the motor can carry, which will cause the motor to run abnormally and cause damage to the motor. [0003] Some current overcurrent protection devices have complex circuit structures, and often cannot protect all six switching tubes of the three-phase bridge arm inside the protection device. When the current is too large, the switching tu...

AI Technical Summary

Problems solved by technology

Excessive current will cause damage to the internal devices of the frequency converter, and the output current of the frequency converter exceeds the maximum current that the motor can carry, which will cause the motor to run abnormally and cause damage to the motor

[0003] Some current overcurrent protection devices have complex circuit structures, and often cannot protect all six switching tubes of the three-phase bridge arm inside the protection device. When the current is too large, the switching tubes will be damaged, and the protection effect is not ideal.

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