新型共直流母线高压变频器

High-voltage Inverter with Novel DC-bus

针对电机叠频试验容易产生较大的有功功率低频波动,在弱电网条件下对电网造成污染导致电网上其他设备无法正常工作,提出了一种新型共直流母线的高压变频器。其整流侧采用移相变压器加二极管整流方案,通过电容串联建立高压直流母线,直流母线储存能量使其不回馈至电网,特别适用于弱电网下的电机叠频试验;逆变侧采用MMC逆变器(Modular Multilevel Converter),通过平衡控制策略达到模块电压平衡,环流抑制的效果。最后应用PSCAD/EMTDC搭建系统的仿真模型,证实了方案的可行性。

This paper proposes an innovative motor drive converter with common dc bus, which especially can be applied for superposed-frequency temperature test under weak grid condition. When a motor drive converter is on superposed-frequency temperature test, there is low frequency active power on the tested motor. If this gird is weak, this active power will contaminate grid and influence other devices. The proposed converter can store this power in the capacitors of dc-bus, instead of feeding back to grid. The rectifier is composed by phase shift transformer and diode rectifier bridges, capacitors of which are series connected to build the high voltage tic-bus. The inverter which is based on MMC（modular multilevel converter）has a common dc-bus. A kind of balnace control is presented to make sure voltage bance between submodules and circurating current supressing. A simulating model is built on PSCAD/EMTDC to certify the utility of the converter.