Method for quickly detecting whether three-phase mains voltage is abnormal

Abstract

Provided is a method for quickly detecting whether the three-phase mains voltage is abnormal. A new variable is defined through a voltage effective value, and the expression of the variable is listed.Three voltage effective value expressions are substituted into the expression of the variable to get a simplified expression of the variable which is dependent of the AC voltage amplitude only and independent of the mains cycle. The simplified expression of the variable is a DC value. The value of the variable is compared with the normal value of mains voltage. If the value of the variable is greater than the allowed maximum value or smaller than the allowed minimum value, the mains voltage is abnormal. According to the detection method, the detection of three AC variables is converted into the detection of one DC value. The detection time from the outage of the mains supply to the work of a rectifier is reduced. The rectifier is opened in time, in order to reduce the amplitude of voltagedrop caused by the fact that a BUS capacitor has no energy input but supplies power to the load all the time. The voltage fluctuation of the BUS capacitor is reduced. The fluctuation of AC voltage converted by an inverter is reduced. The stability of power supply to the load is improved. A high-quality AC power supply can be provided for the load.

Description

technical field [0001] The invention relates to the technical field of electric power equipment, in particular to a method for quickly detecting abnormal voltages of three-phase commercial power. Background technique [0002] UPS, uninterruptible power supply, is a system device that connects batteries (mostly lead-acid maintenance-free batteries) with the host, and converts direct current into commercial power through modular circuits such as the host inverter. UPS provides customers with uninterrupted power supply. When the mains power is abnormal, it needs to cut off the AC input and switch to DC power supply. It is critical to quickly detect the abnormality of the mains voltage. However, the detection technology in the prior art uses the effective value of the mains to calculate, and then judges whether the mains voltage is abnormal according to the calculation result of the effective value of the mains. The effective value of the mains needs at least half a cycle, and ...

AI Technical Summary

Problems solved by technology

It is critical to quickly detect the abnormality of the mains voltage. However, the detection technology in the prior art uses the effective value of the mains to calculate, and then judges whether the mains voltage is abnormal according to the calculation result of the effective value of the mains. The effective value of the mains needs at least half a cycle, and the detection time is too long, which causes the BUS capacitor voltage to fluctuate too much, and the converted AC output voltage fluctuates too much, which affects the normal operation of the load

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