矿用宽输入电压范围级联变换器设计

Design of mine cascade converter with wide input voltage range

针对目前用于电源的变换器电压增益低、功率管电压应力大、电气非隔离、控制复杂等问题,为满足煤矿AC127~1140 V供电电压等级,设计了一种矿用宽输入电压范围级联变换器,能够自适应AC70~1400 V电压输入。该变换器采用3路Buck变换器与LLC变换器串联方式提高变换器电压增益;采用电容串联分压方式降低功率管电压应力;Buck变换器采用输入电压前馈补偿降低输入电压波动影响,同时通过输出电压闭环PI调节以提高变换器稳定性;LLC变换器具有输入输出电气隔离性能,采用脉冲频率调制技术对输出电压进行闭环PI调节,再通过压控振荡器对功率管进行变频驱动,调节变换器谐振频率,从而稳定输出电压。仿真和实验结果表明,在输入电压为AC70~1400 V时,变换器负载效应在5%以内,输出电压偏离值在5%以内,满足MT/T 408-1995《煤矿用直流稳压电源》要求。

The converter used in the power supply has problems of low voltage gain,high voltage stress of power tube,non-electrical isolation and complex control.In order to solve the above problems,a mine cascaded converter with wide input voltage range is designed to meet the requirements of AC127-1140 V power supply voltage level of coal mine.The cascaded converter can adapt to AC70-1400 V voltage input.The converter adopts 3-way Buck converter and LLC converter in series to improve the voltage gain of the converter.Capacitor series voltage divider is used to reduce the voltage stress of power tube.Buck converter adopts input voltage feedforward compensation to reduce the influence of input voltage fluctuation.At the same time,Buck converter improves converter stability through output voltage closed-loop PI regulation.LLC converter has the performance of input and output electrical isolation.Pulse frequency modulation technology is used to perform closed-loop PI regulation on the output voltage.Then the power tube is driven by a voltage controlled oscillator with frequency conversion to adjust the resonant frequency of the converter,thus stabilizing the output voltage.The simulation and experimental results show that when the input voltage is AC70-1400 V,the load effect of the converter is less than 5%and the output voltage deviation is less than 5%.These results meet the requirements of MT/T 408-1995 DC stabilized power supply for coal mine.