Research On The Modulation Strategies Of Parallel-connected Open-winding Permanent Magnet Generator System

Permanent magnet synchronous generator(PMSG) has been widely used in the vehicle power system and wind energy conversion system for its merits of high power density, simple structure and high efficiency. However, it is difficult to regulate the air-gap magnetic result in the narrow speed range and poor voltage regulation for the generation system composed of conventional PMSG and three phase voltage source PWM rectifier. To solve the above problems, this paper adopts an open-winding generator structure and studies the modulation strategies of the open-winding generation system.Firstly, this thesis gives topology structure of parallel-connected open-winding PMSG system composed of full-bridge converter, open-winding PMSG and rectifier and the mathematical model of open-winding PMSG are demomstrated. The inducement of zero-sequence current is analyzed under the conventional SVPWM method for the dc sides of full-bridge converter and rectifier connected together. On the basis, the hysistere control and SPWM method are adopted to improve the system characteristics and the control diagrams are given. Moreover, by analyzing the reasons of the exist harmonics in the above strategies an improved SPWM method is proposed to improve the current control performance.Secondly, the simulation model of parallel-connected open winding PMSG system is established to under the above modulation strategies. The simulation result comparisons among these strategies verifiy the theoretical feasibility.Finally, the hardware platform is established based on the TMS320F2812 and CPLD as the core controller. The experiment is also conducted on an open-winding PMSG of 1k W power ratings. The good performance and feasibility of the modulation strategies adopted is verified by the experimental results.