Three-phase AC motor phase loss protection circuit

Abstract

The invention discloses a three-phase AC motor phase loss protection circuit which comprises voltage detection circuits connected with a three-phase voltage circuit. The three voltage detection circuits are connected in parallel and then connected with a phase loss determining circuit, each voltage detection circuit comprises a current limiting resistor, the current limiting resistor is connectedwith a diode and an optoelectronic coupler in parallel and then outputs a control signal and a phase line signal; the phase line signal is output to the phase loss determining circuit, and the phase loss determining circuit taking the triode as the main part determines phase loss of the voltage detection circuits, and then outputs a phase loss determining signal and is connected with a controller;the controller makes phase loss judgment, and then emits a control signal and returns the control signal to the circuit, and the control signal Uqb is connected with a power switch of a motor. The circuit is simple, reasonable, safe and reliable, the detection method is simple, and it is ensured that equipment is not damaged.

Description

technical field [0001] The invention relates to a protection circuit, in particular to a phase-loss protection circuit of a three-phase AC motor. Background technique [0002] Frequency conversion speed regulation has become the mainstream speed regulation method, and the frequency converter is the core part of the speed regulation system. In the industrial control industry, the lack of phase operation of the inverter will cause damage to devices and machines. In addition, in some special fields, industrial frequency conversion is required, which requires the frequency converter to judge the consistency of its input phase sequence to avoid harm to its equipment. In order to avoid damage to the frequency converter, many frequency converters have defect detection circuits and phase sequence detection circuits. [0003] The common method in the existing technology is to collect the current of each phase of the three-phase motor, carry out AD sampling to the single-chip microc...

AI Technical Summary

Problems solved by technology

However, this detection method requires the addition of operational amplifiers, and also requires the MCU to perform a large number of algorithm processing, resulting in a waste of chip resources. At the same time, due to the complexity of software control, it will also increase the risk of software unreliability.

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