一种新型单象限变频器预充电电路设计

针对传统的单象限变频器预充电电路存在结构和控制复杂,接触器、充电电阻等主要器件成本高、体积大的问题,设计了一种新型单象限变频器预充电电路。该电路采用三相半控整流桥替换传统的单象限变频器预充电电路中的二极管整流桥,并去掉了接触器和充电电阻;当变频器启动时,通过同步电路和单片机控制电路,三相半控整流桥的触发角从120°有规律地减小到0°,从而可使电容的充电电流在允许范围之内。试验结果表明,该电路结构简单、性能可靠、控制灵活。

Design of a new type of pre-charge circuit of single-quadrant frequency converter

In view of problems of complex structure and control,high cost and big volume of contactor and charging resistance existed in traditional pre-charge circuit of single-quadrant frequency converter,a new type of pre-charge circuit of single-quadrant frequency converter was designed.The circuit uses three-phase half control rectifier bridge to replace diode rectifier bridge of traditional pre-charge circuit of single-quadrant frequency converter and takes off contactor and charging resistance.When the frequency converter starts,trigger angle of the three-phase half control rectifier bridge decreases rhythmically from 120° to 0°through synchronization circuit and single-chip microcomputer control circuit,so as to make charging current of capacitance in allowable range.The test result showed that the circuit has simple structure,reliable performance and flexible control.