Niu Liyong

Study on optimum design procedure of charger based on full-bridge phase-shifted ZVZCS converter

An optimum design procedure of an Electric Vehicle charger based on a full-bridge phase-shifted zero-voltage and zero-current switching (FB-PS-ZVZCS) dc-dc converter is proposed. The converter uses a small capacitor and two small diodes to form the clamp circuit, which makes the converter simple and easy to control. According to the analysis of the operation principles, several conclusions about the influences of the converterpsilas main parameters to the operating characteristics and the restrictions between parameters are drawn. Based on the conclusions, a parameter optimum design procedure is proposed. The proposed procedure can be used to design the values of the switches snubber capacitor, the clamp capacitor, the transformerpsilas turns ratio and the maximum duty cycle, etc. By using the proposed procedure, a converter prototype is designed. The prototype is simulated in Matlab/Simulink and verified by experiments. The simulation and experiment results validated the parameters as well as the proposed optimum design procedure.

A Study on Battery Management System of Ni-MU Bat ery Packs for Hybrid Electric Vehicle Applications

This paper proposes a decentralized battery management system (BMS) of nickel metal hydride (Ni-MH) battery packs for hybrid electric vehicle (HEV) applications, which is necessary and important to guarantee the Ni-MH battery packs performance in the HEV application. The presented BMS, which consists of a central management unit and data acquisition modules, features the characteristics of reduced wiring, great ability of expansion, easy installation, and high precision and reliability. The estimation algorithm of the state of charge (SOC) of the battery pack combines the open circuit voltage method and the coulometer method in order to obtain high precision.

An approach to improve efficiency of EV batteries charger under light load

This paper presented an approach to improve efficiency of EV batteries charger under light load. On the basis of analysis on the original charger built upon capacitor-diode-diode clamp circuit, a modified capacitor-diode-switching clamp circuit was designed to replace the original one in the full-bridge phase-shifted zero-voltage and zero-current-switching PWM DC/DC converter. Operating principle was introduced, and the critical condition to judge whether under light load was derived. Circuit simulation and experiment on the prototype were performed under different loads. Both results show that besides the advantages of the original topology, higher efficiency and less stress on switches are achieved under light load.