Frequency converter input power supply open-phase detection method

Abstract

The invention relates to a frequency converter input power supply open-phase detection method, belongs to the frequency converter input power supply detection field and is suitable for performing open-phase detection of three-phase input equipment such as a frequency converter and EPS. The method is mainly characterized in that the frequency converter DC bus voltage amplitude Udc is acquired in real time; the frequency of fundamental waves of the power supply is taken as the fundamental wave frequency, and the amplitude Amp_Hn of DC bus voltage harmonic waves is calculated; 2nd-7th harmonic waves of the DC bus voltage harmonic waves are selected as DC bus voltage characteristic harmonic waves; the content Value_H of the DC bus voltage characteristic harmonic waves is calculated and is equal to a square root value of the sum of squares of the amplitude Amp_Hn of the selected DC bus voltage characteristic harmonic waves; the content Value_H of the DC bus voltage characteristic harmonic waves is compared with a preset determination threshold Value_Set; all the above cycle steps are repeated, when the content Value_H of the DC bus voltage characteristic harmonic waves exceeds the preset determination threshold Value_Set, that the frequency converter input power supply is in open-phase is determined.

Description

technical field [0001] The invention relates to the field of frequency converter input power detection, in particular to a three-phase input power phase loss detection method. Background technique [0002] Inverters have been widely used in the industrial field. When the inverter is input with three-phase power, the stability of the power supply is crucial to the operation of the inverter. Therefore, the input power phase loss protection function has been used as the most basic protection of the inverter. Features. [0003] The traditional input power phase loss detection method uses hardware circuit detection. The three-phase input power signal is sampled through the sampling circuit. After a series of processing, the input phase loss is judged by waveform comparison; the circuit cost and complexity are increased, and PCB space is occupied. Especially low-power inverters are small in size, saving space is especially valuable. Contents of the invention [0004] The purpo...

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Problems solved by technology

[0003] The traditional input power phase loss detection method uses hardware circuit detection. The three-phase input power signal is sampled through the sampling circuit. After a series of processing, the input phase loss is judged by waveform comparison; the circuit cost and complexity are increased, and PCB space is occupied. Especially low-power inverters are small in size, saving space is especially valuable

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