Analysis And Inhibition On Short Current In Inductive Power Transfer System

Wireless Power Transfer Technology is a research hotspot recent years. Scientists and engineers have took effort to do research in the field because of its wide and brilliant application prospect. As a kind of mainstream technology in Wireless Power Transfer Technology field, inductive power transfer(IPT) technology has been applied to implement practical system for many years. A lot of research findings about inductive power transfer technology have been used to make smaller and more efficient system. However, compared to Voltage-Fed Type IPT system, Current-Fed type IPT system has been ignored by researchers. There are few research production related to Current-Fed type IPT system, which restrict its application. In practical Current-Fed IPT system, because of existence of short current, switching devices is easy to damage and Current-Fed Type IPT system is hardly used in practice.Based on Current-Fed Type IPT system, this paper focuses on the shot current generated in the system. Some researches are done and been listed below:(1) The thesis analyses the mechanism of short current in Current-Fed Type IPT system, and proposes a simple criterion to determine whether the system could generate short current or what kind of short current the system generates.(2) The known short-current-controlling method is listed, and train of thought to control short current is discussed.(3)An inductance-damping method is proposed to eliminate the danger of short current. An extra inductance is connetced in series with the output port of the inverter to reduce peak value of short current. An overlopping time is introduced to PWM pulse. Switching devices in the inverter can turn on with ZCS and turn off with ZVS. Steady-state operating conditions is discussed, a simple overlapping time circuit is proposed and L1_cri is calculated accurately. The design flowchat is put forward and an experimental system is designed. Finally, a prototype is built to verify the method.(4)An input-current-discontinious-mode method is proposed to eliminate the short current. Theoretical model is established and some important parameters in the system is calculated. In the system, LDC is so small that system's weight and volume is greatly reduced. The experimental system is designed, in which constant-on-time PWM pulse is applied. Experimental result is analysed. Finally, a prototype is built to verify the method.