A new isolation control of three-port active converters for electric vehicles

Three-port active converter which has three full bridge ports can work as a combined charger of an on-board charger and a DC-DC converter in electric vehicles. At the time the on-board charger is working, the DC-DC converter is in isolation state. This paper comes up with an isolation control. In this isolation control, the on-board charger firstly adopts constant current charging to charge main battery. That is to say during the constant current charging state, power transfer from AC side to the main battery while the auxiliary battery is isolated. Power transmission and vector diagram is given to deduce the isolation mathematical equations. Based on the isolation equations, control block diagram is given. The results of simulation are given to verify the effectiveness of this control strategy.