Research On The New Isolated Threeport-converter And Conctrl Strategy

Based on the research background of mobile vehicle power supply,this paper analyzes and studies the topology of TPC(Isolated Three-port Converter),and gives the hardware implementation method of the isolated three-port converter decoupling based on the port power characteristics.And on the basis of power decoupling,the soft switching range and current stress are optimized.First,by establishing the Y-type and(35)-type equivalent model of the isol-ated three-port converter and then equating it to multiple DAB,(Dual-Active-Br-idge)with power coupling,we can deduce power transmission equation of each port.On the basis of the equation of the power transmission,the coupling relationship between the control variables of each port is obvious,and a new isolated three-port topology is proposed.Secondly,a new isolated-three-port converter which decoupled ports' power based on multi-resonance is proposed.According to the equivalent model of the topology,the Fourier decomposition analysis method is used to derive the decoupled port current size,soft switching range and port power transfer equation,and we analyze every port soft switching range under different load and voltage matching degrees range then we deduced the magnitude of current stress.According to the steady-state model of the topology,the resonance parameters of the system are selected,and a small-signal model is established for the topology and then two independent control loops are designed.The decoupling performance of the new three-port converter is simulated and verified.According to the effect of different port voltage matching degree and load size which influence each port soft switching range and current stress,the port internal phase shift is introduced on the basis of signal phase shift control.Two different optimized control algorithms are adopted to achieve ZVS(Zero-Voltage-Switch)of the high voltage side voltage companying the voltage floating and reduce the current stress of the low voltage side port,thereby it reduced the loss of the converter.Finally,based on the construction of a new isolated three-port converter model,different system control strategies are designed for different applications(photovoltaic panels/charging piles),which can achieve the MPPT of the photovoltaic module and the current limiting/voltage of the battery port.And load port voltage regulation control.Aiming at the nonlinearity between the transmission power of the photovoltaic port and the topology phase shift angle control,a nonlinear control scheme is proposed,and the effectiveness of the control strategy of the system is verified by simulation.