The Study Of PWM Rectifier In Energy Storage System

Electrical energy is an indispensable secondary energy source in human social and economic activities. With the development of national economy, the demand of electrical energy is rapidly increased. With the continuous consuming of fossil fuels, we realized that the development and utilization of renewable energy, such as wind energy, hydropower and solar energy, is more and more important. In order to ensure the stability of power supply with renewable energy systems, the feasible energy storage technology should be developed. The energy storage system plays an important role in regulating power peak, stabilizing electricity networks and efficiently using of renewable energy.An energy storage system normally consists of two major parts, one is energy storage device composed of storage components, and the other is power grid interfacing module composed of power electronic devices. The latter is the research topic focused in this dissertation. Three-phase voltage-type PWM rectifier is the first choice for power conversion in an energy storage system, because of the favorite behavior of sinusoidal current, high power factor and bidirectional energy flow.Firstly, the dissertation discusses the control method of a three-phase voltage-type PWM rectifier in detail. The modulation principle of the voltage space vector (SVPWM) and its digital realization method are analyzed. Secondly, the hardware design of the three-phase voltage-type PWM rectifier are presented in detail, including the design of main circuit, signal conditioning, control circuit and the circuit parameters. A microcontroller and a CPLD are combined to function as the digital controller. Thirdly, programming of control algorithm is described. The programming mainly contains interrupt service routines, digital PI control algorithm, and SVPWM modulation. Finally, an experiment based on a prototype platform of energy storage system is explained according to the design requirements. The experiment achieves bidirectional power flow with additional control of a DC-DC converter.Experimental results show that operation of the bidirectional PWM rectifier base on SVPWM modulation cannot only eliminate harmonic elements and improve power factor, but also enhance the DC voltage utilization and reduce the switch frequency.