Fault detection method of three-phase power supply

Abstract

The invention discloses a fault detection method of a three-phase power supply. The fault detection method of the three-phase power supply includes the following steps: first, rectifying and filtering the three-phase power supply to direct current (DC) bus voltage; second, detecting the direct current (DC) bus voltage, working out ripple voltage delta V; then, judging whether the three-phase power supply is damaged according to the ripple voltage delta V. According to the detection method of the three-phase power supply, abnormal conditions of phase failure, phase voltage unbalance and momentary power failure of the three-phase power supply can be detected accurately, and high power loads which apply the three-phase power supply to supply electricity can be protected rapidly by the fault detection method of the three-phase power supply. If the fault detection method of the three-phase power supply is applied to power-supply protection design of frequency-converted loads, the frequency-converted loads and rectifying circuits and inverter circuits of drive circuit of loads can be protected effectively, probabilities of problems that damage in the frequency-converted loads, the rectifying circuits and the inverter circuits and the like caused by abnormity of power grids can be decreased, circuit design can be simplified and hardware cost can be reduced and reliability of products is enhanced at the same time.

Description

technical field [0001] The invention belongs to the technical field of power supply detection, and in particular relates to a detection method for detecting whether a three-phase AC power supply is abnormal. Background technique [0002] The three-phase rectifier circuit is a circuit that converts three-phase AC power into DC power. It has been widely used in the fields of DC motor speed regulation, generator excitation regulation, electrolysis, and electroplating. Moreover, with the development of emerging technologies and the continuous expansion of market demand, three-phase rectification technology has also been more and more widely used in home appliances. [0003] Three-phase AC power is mostly used in high-power occasions. At present, for high-power inverter air conditioners above 5KW, three-phase power is usually used for power supply, which can meet the needs of large-scale families, some factories or public places. The three-phase power supply is required in air-c...

AI Technical Summary

Problems solved by technology

Due to the uneven current flowing through the rectifier diodes D1-D6, some rectifier diodes heat up, and the internal resistance of the rectifier diodes has the characteristics of a negative temperature coefficient, that is, the higher the temperature of the diode, the smaller its internal resistance, and the internal resistance The smaller the diode, the greater the current flowing through it, which leads to a vicious cycle, and long-term operation will cause the breakdown of the rectifier diode

The harm of three-phase power supply phase loss is the extreme case of three-phase voltage unbalance, so the harm caused by this situation will be more serious

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