在中压电机驱动应用中，模块化多电平换流器(modular multilevel converter，MMC)因其子模块(submodule，SM)中存在波动功率而需要大容值电容，导致功率密度降低。文中提出一种高频链互联 MMC(high-frequency link interconnection MMC，HFL-MMC)拓扑方案，该拓扑将同一水平位置的三相 SM 间通过高频链(high-frequency link interconnection，HFL)实现互联，利用三相SM波动电流的对称性实现波动功率解耦，从而抑制SM电压波动和桥臂二倍频环流，大幅减小 SM 电容体积。介绍所提 HFL-MMC拓扑的系统配置和波动功率解耦原理;详细分析该拓扑中HFL 的工作过程与模式及其在工程常规硬件参数范围内的波动功率解耦特性和零电压开关特性;对该拓扑和传统MMC进行功率密度、效率和成本的对比评估。最后，对所提HFL-MMC电机驱动系统进行仿真和实验验证。
Optimization Design of Power Density for Cascaded Modular Medium Voltage Motor Drive System
In the application of medium voltage motor drives,the modular multilevel converter(MMC)requires large-size capacitance to mitigate ripple power in its submodule(SM),resulting in reduced power density.A high-frequency link interconnection MMC(HFL-MMC)topology is proposed,which connects the three-phase SM at the same horizontal position through a high-frequency link(HFL)and decouples ripple power based on the symmetry of fluctuating current of the three-phase SM.This effectively suppresses voltage fluctuations of the SM,greatly reducing the volume of SM capacitors.Furthermore,the 2nd-order frequency circulating currents in arms are also eliminated.This paper presents the system configuration and ripple-power decoupling principle of the HFL-MMC.The working process and mode of the interconnected high-frequency link in this topology are analyzed in detail,along with its ripple-power decoupling characteristics and zero-voltage-switching(ZVS)characteristics within conventional engineering hardware parameters.Furthermore,an evaluation is conducted on the power density,efficiency,and cost of both this topology and traditional MMC.Finally,the HFL-MMC motor drive system is verified through simulation and experimentation.
motor drivemodular multilevel converter(MMC)power densityripple power
万方数据
维普
