Synchronous reference voltage based multiple PWM (pulse width modulation) converter parallel operation control method

Abstract

The invention discloses a synchronous reference voltage based multiple PWM (pulse width modulation) converter parallel operation control method. A multiple PWM converter parallel operation system comprises a master controller and slave controllers, the master controller calculates synchronous output reference voltage of each PWM converter according to total power of loads in parallel operation, synchronous reference voltage signals outputted by the master controller are sent to the slave controllers, and each slave controller corrects a virtual output impedance value thereof automatically according to self load power, so that total input power of the PWM converters meets system demand as well as self load demand of each PWM converter. Equivalent output terminal voltage of each PWM converter has completely consistent amplitude and phase, thus, circular current between the PWM converters is avoided; and since each PWM controller is provided with one independent slave controller, when one of the PWM converters is fails, the rest PWM converters can still continue working, and system stability is improved.

Description

technical field [0001] The invention relates to a control method applicable to a system of parallel operation of multiple PWM converters, in particular to a master-slave control method for parallel operation of multiple PWM converters for suppressing circulating current. Background technique [0002] The traditional industrial frequency conversion power supply is usually composed of power diodes and thyristors. After the AC power supply or DC power supply is converted by the traditional industrial frequency conversion power supply, a large number of harmonics will be injected into the power grid. With the development of industry, the application of variable frequency power supply is becoming more and more extensive, especially the number and capacity of various high-power rectifier power supplies and special inverter power supplies based on power switching devices used in the metallurgical industry are becoming larger and larger. The impact of industrial variable frequency p...

AI Technical Summary

Problems solved by technology

However, when the voltages on the AC side of the PWM converters in the power modules running in parallel are inconsistent, a circulating current will be generated between the PWM converters

The circulating current between the converters will increase equipment loss, reduce the power conversion efficiency of the variable frequency power supply, and cause burnout hazards to the power switching devices in the PWM converter when the circulating current is large

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