级联型电压自平衡固态变压器

Cascaded voltage self-balancing solid state transformer

传统的级联型固态变压器存在级联单元间直流母线电压不平衡的问题,严重影响系统的稳定运行。常规的解决办法是控制各个级联脉宽调制(PWM)整流器或者双向DC-DC变换器,来调节每个单元的直流母线电压大小,但其控制复杂,运算量巨大,在级联数量较大时甚至无法使用。该文提出了一种新型的具有电压自平衡能力的级联型固态变压器,介绍了其拓扑结构和控制方法,分析了其自平衡的工作原理,并研究了其参数变化的影响。这种级联型固态变压器不需要任何额外的电压平衡控制,完全依靠拓扑电路实现电压的自动平衡,能够大大简化控制系统。仿真结果验证了该固态变压器的电压自平衡能力,表明其具有良好的工作性能。

Traditional cascaded solid state transformers have the problem of unbalanced DC bus voltages in cascaded units DC, which seriously threatens stable system operation. Conventional solutions include controlling each cascaded pulse width modulation （PWM） rectifier or dual DC-DC converters to adjust the DC bus voltages of each cascaded unit, but the control system is quite complex and does not work well with many cascaded units. A self-balancing voitage cascaded solid state transformer is introduced here with its topology and control system with analyses of its working principle and the effects of the control parameters. The system achieves voltage self-balancing based on only the main circuit without any extra voltage balance control, so its control system is much simpler. Simulations illustrate its self-balancing ability and its good performance.