Open-phase detection circuit of three-phase variable-frequency electromotor

Abstract

The invention discloses an open-phase detection circuit of a three-phase variable-frequency electromotor, which comprises a three-phase current sampling module, a rectifier module, an integrator module and a comparator module, wherein the three-phase current sampling module is used for sampling current of each phase of a three-phase variable-frequency electromotor to generate an alternating-current voltage sampling signal; the rectifier module is connected with the three-phase current sampling module and used for converting the alternating-current voltage sampling signal into a unidirectional voltage signal with a preset gain; the integrator module is connected with the rectifier module and used for converting the unidirectional voltage signal into a direct-current voltage signal; and the comparator module is connected with the integrator module and used for comparing the direct-current voltage signal with a preset reference voltage to perform open-phase determination on the three-phase variable-frequency electromotor. The open-phase detection circuit of a three-phase variable-frequency electromotor can quickly and accurately detect whether the three-phase variable-frequency electromotor is in an open-phase state, is strong in anti-interference performance and high in reliability, and is beneficial to quickly realize open-phase protection on the three-phase variable-frequency electromotor.

Description

technical field [0001] The invention relates to the technical field of three-phase motors, in particular to a phase loss 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 the concept of high efficiency and energy saving, the speed regulation method using frequency converter to drive the motor has been greatly developed, which greatly improves the degree of mechanical automation and production efficiency, and its equipment is miniaturized , The range of speed regulation is large, and it is currently replacing the traditional mechanical speed regulation 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. Three-phase asynchronous motors have abnormal vi...

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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