Control system and method for synchronous switching of frequency converter and industrial frequency converter

Abstract

The embodiment of the present invention discloses a frequency converter, industrial frequency conversion synchronous switching control system and method, which ensures that the voltage phase at the input terminal of the load is synchronized with the mains voltage phase, reduces the impact on the load and the frequency converter when the industrial frequency conversion is switched, and improves the system stability. . The frequency converter provided by the embodiment of the present invention includes: a voltage detection circuit, a phase-locked control module and a main circuit, the voltage detection circuit is connected with the phase-locked control module, and an inverter output terminal is provided on the main circuit; the voltage detection circuit includes a mains The detection circuit and the load detection circuit, the input end of the mains detection circuit is connected with the voltage output end of the mains to detect the mains voltage, and the input end of the load detection circuit is connected with the load voltage input end to detect the load input voltage; When the phase of the voltage at the load input terminal is inconsistent with the phase of the mains voltage, the phase lock control module makes the phase of the voltage at the load input terminal consistent with the phase of the mains voltage by controlling the voltage phase of the inverter output terminal.

Description

technical field [0001] The invention relates to the field of electromechanical control, in particular to a frequency converter and an industrial frequency conversion synchronous switching control system and method. Background technique [0002] The traditional frequency converter with phase-locking function is mainly used for phase-locking the mains power supply and the inverter output of the frequency converter, so as to realize the switching between industrial frequency and variable frequency. If there is a transformer or filter that produces a phase shift between the inverter output of the inverter and the load, the inverter voltage will cause a phase shift of the original inverter output voltage after passing through the transformer or filter, resulting in a phase shift in the inverter output. There is a phase difference between the voltage and the load input terminal voltage, and the traditional inverter with phase-locking function cannot detect this phase difference at...

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Problems solved by technology

If there is a transformer or filter that produces a phase shift between the inverter output of the inverter and the load, the inverter voltage will cause a phase shift of the original inverter output voltage after passing through the transformer or filter, resulting in a phase shift in the inverter output. There is a phase difference between the voltage and the load input terminal voltage, and the traditional inverter with phase-locking function cannot detect this phase difference at the moment of industrial frequency conversion switching, which will cause great impact and damage to the load, which will make the system unstable or abnormal. ;In addition, because the traditional frequency converter with phase-locking function has a large impact on the load, great damage, and the switching voltage drops and is not stable, the power of the frequency converter is usually required to be several times larger than the load, which leads to high costs; for power frequency switching For loads that require high phase synchronization, such as lighting loads (sodium lamps, halogen lamps, or neon lamps, etc.), if the phases are not synchronized during power frequency conversion, the lighting loads will go out, and the startup time of the lighting loads is very short. long, which will seriously affect its normal use

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