中文摘要：

针对传统中压变频器中移相变压器体积大、接线多、重量大的问题,提出了一种级联式多电平整流电路拓扑。该拓扑无需采用工频移相变压器,而是由二极管整流桥和级联Boost电路模块单元构成,可实现单位功率因数整流、级联模块单元的稳压输出和均压控制。讨论了拓扑的基本工作原理、稳态特性,对其关键参数（升压比,负载不平衡度和电感值）进行了推导,并给出了相应的控制策略。仿真与实验结果验证了所提拓扑和控制策略的可行性。

英文摘要：

In allusion to the bulky volume, heavy weight and too much connection terminals ＂of the phase-shifting transformer in traditional medium-voltage frequency converter, a topology for a cascade multilevel rectifier is proposed. Not needing power frequency phase-shifting transformer, the proposed topology is composed of H-bridge diode rectifier and cascaded boost circuit modular units, by which the unity power factor rectify, the output of stabilized voltage of cascaded modular units and voltage-sharing control can be implemented. The basic working principle of the proposed topology, its steady state characteristics are discussed, and the key parameters, such as the boost ratio, the degree of load unbalance and the value of inductance, are derived and corresponding control strategy is given. The feasibility of the proposed topology and control strategy is validated by simulation results and experimental results.