Phase loss detection circuit of three-phase variable frequency motor

Abstract

The invention discloses a phase-lack detection circuit of a three-phase variable-frequency motor, which comprises: a three-phase current sampling module for sampling each phase current of a three-phase variable-frequency motor to generate an AC voltage sampling signal; a rectifier module, the rectifier module Connected to the three-phase current sampling module, used to convert the AC voltage sampling signal into a unidirectional voltage signal with a preset gain; an integrator module, the integrator module connected to the rectifier module, used to convert the The unidirectional voltage signal is converted into a DC voltage signal; a comparator module, the comparator module is connected to the integrator module, and is used to compare the magnitude of the DC voltage signal and a preset reference voltage to convert the three-phase frequency The phase loss of the motor is judged. The open-phase detection circuit of the three-phase variable-frequency motor of the present invention can quickly and accurately detect whether the three-phase variable-frequency motor is open-phase, has strong anti-interference performance and high reliability, and is beneficial to quickly realize phase-loss protection for the three-phase variable-frequency motor.

Description

Technical field [0001] The invention relates to the technical field of three-phase motors, and in particular to a phase lack detection circuit of a three-phase variable frequency motor. Background technique [0002] In recent years, with the rapid development of frequency conversion control technology and the promotion of high-efficiency and energy-saving concepts, the speed regulation method of using frequency converters to drive motors has been greatly developed, which greatly improves the degree of mechanical automation and production efficiency, and its equipment is miniaturized , The speed range is large, and it is currently replacing the traditional mechanical speed control scheme. [0003] Among them, the variable frequency motor is divided into three-phase synchronous motor and three-phase asynchronous motor, but the hardware structure of the variable frequency drive of the two is basically the same. The three-phase asynchronous motor has abnormal vibration and noise when ...

AI Technical Summary

Problems solved by technology

Three-phase asynchronous motors have abnormal vibrations and noises when they are running with a lack of phase. If they are not stopped in time, the temperature of the windings will rise too high and the motor will be burned. However, when the three-phase synchronous motors are running with a lack of phase, the remaining two-phase current will increase abnormally. , if the phase loss causes the motor to lose step, it will generate a strong current impact (usually the current rise rate reaches 10A / ms), which will cause the permanent magnet of the rotor to demagnetize. Therefore, it is very important to quickly detect and protect the three-phase motor for phase loss

However, the disadvantages of the existing technology are that when the software algorithm is used to detect and protect the lack of phase of the three-phase motor, the detection speed is limited by the operating frequency of the controller, which prolongs the protection time, and the detection accuracy is also susceptible to electromagnetic interference. High error rate and low reliability

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