Method for detecting input phase failure of three-phase input device

Abstract

The invention discloses a method for detecting an input phase failure of a three-phase input device, wherein the method is suitable for phase failure detection of three-phase input devices such as a frequency converter, an EPS (Emergency Power System) and the like. The method comprises the steps of rectifying and filtering a three-phase input voltage of the three-phase input device and then obtaining a DC (Direct Current) busbar voltage; sampling the DC busbar voltage at a certain time interval t, wherein t is less than and equal to 1 / 6 of an input power supply cycle; when n continuously monotonous sampled voltage values occur in the sampled voltage values, judging that the input phase failure exists; and when any n continuously monotonous sampled voltage values do not exist in the sampled voltage values, judging that no input phase failure exists. Compared with the traditional detection method, the method for detecting the phase failure, provided by the invention, dispenses with a special hardware circuit, so that the cost is saved; and simultaneously, the sampled DC busbar voltage is detected in the method by software, so that and the method achieves the advantages of high reliability, flexible design, suitability for various power grid conditions and less EMC (Electro Magnetic Compatibility) interference.

Description

technical field [0001] The invention discloses an input phase loss detection method of three-phase input equipment, which is suitable for the phase loss detection of three-phase input equipment such as inverters and EPS. Background technique [0002] Due to the complex working environment of the inverter, sometimes there will be a phase loss of the power supply. If this situation is not protected, it may cause damage to the inverter. Therefore, the inverter will detect the input phase loss. The traditional input phase loss detection is realized by hardware circuit, please refer to the attached figure 1 , figure 1 It is a commonly used phase loss detection circuit at present. The three-phase input terminals respectively limit the input current through the current limiting resistor R1-current limiting resistor R3, and then rectify the input voltage through the full-bridge rectifier diode D1-full-bridge rectifier diode D3; voltage to reduce the rectified voltage; the optocou...

AI Technical Summary

Problems solved by technology

[0004] The above phase loss detection circuit has the following problems: (1) The above phase loss detection method is implemented by using a hardware circuit, which will generate a certain hardware cost; The loss is large, the heat is serious, and it is easy to cause poor reliability of the circuit; (3) The circuit is directly connected to the power input terminal, and the high-voltage power has great interference on it, and the anti-interference ability of the circuit itself is poor. It is easy to cause EMC problems, and cannot guarantee normal operation in the case of harsh electromagnetic environments

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