Research On Key Control Techniques Of Integrated Driving And Charging System Of Electric Vehicle

Electric vehicle(EV)with on-board charger has independent driving system and charging device,which leads to the increasement of the cost and weight and also wastes the limited space resource.Hence,the research of how to integrate EV's driving system with the charger has become a hot and difficult topic.In this dissertation,a novel integrated topology of EV's driving system and changer is presented.The technology of driving control and fault-tolerant control of three-phase opening winding permanent magnet synchronous motor(TPOW-PMSM)under traction mode is studied,which is designed to guarantee reliable operation of the system.In the aspect of two parallel three-phase PWM rectifiers under charging mode,the technologies of high power factor and harmonic suppression are studied in the dissertation,the output current balance and circulation current suppression are developed in the proposed system.Initially,the status of EV's integrated topology in domestic and overseas is systematically analyzed.The current research situation of opening winding motor and its control technology is discussed in detail.Thus,a new EV's integrated driving and charger topology is proposed.The two parallel inverters of the driving system of the proposed integrated topology can be reconstructed into two parallel three-phase PWM rectifiers of the charging system.The two parallel bidirectional DC/DC converters are used simultaneously,which improves the system's power density.At the same time the number of detection components of the system is reduced.The designed integrated topology reduces the volume,the weight and the cost of the vehicle.TPOW-PMSM's mathematical model is established in different coordinates.The topology and working principle of each subcircuit of the proposed EV's integrated topology are analyzed.Furthermore,the driving control technology of TPOW-PMSM in traction mode is studied.For the normal speed operation and control of TPOW-PMSM system,with the goal of not producing zero sequence voltage and zero sequence current,a medium vector hexagon control strategy for TPOW-PMSM system is proposed,the vector control system of TPOW-PMSM is designed.A hybrid control strategy with PI and repetitive control for speed loop is designed.Compared with Y-connected winding PMSM(YCW-PMSM)vector control system,the simulation and experimental results show that: TPOW-PMSM system has advantages like fast dynamic response,strong anti-interference ability,stable speed,etc.,what's more,it eliminates the influence of zero sequence current on the system.In order to obtain the maximum voltage modulation range and high-speed operation,a large vector hexagon control strategy for TPOW-PMSM system is proposed,and the algorithm is given simultaneously.The effect of the switch's dead time on the zero sequence voltage is analyzed.The method of adjusting zero vector to suppress zero sequence voltage is introduced.An improved adjusting zero vector SVPWM control strategy with zero sequence current suppressor is presented,which improves the DC voltage utilization of the two parallel inverters.Experimental results show that: the zero sequence current can be effectively suppressed by this control strategy,the reliable operation of TPOW-PMSM system is guaranteed.Moreover,the fault tolerant control technology for TPOW-PMSM system in traction mode is researched.The inverter's fault type,fault-tolerant method and topology reconfiguration of the integrated system are thoroughly discussed.The voltage space vector distribution of three-phase 3 H-bridge inverter is analyzed when single tube opening fault.An improved small vector hexagon control strategy for fault phase shorting-connected is proposed.A two-phase SPWM control strategy for fault phase opening is proposed,which can ensure to obtain the maximum torque.Based on the speed and current double closed-loop control,the control of motor speed and non-fault phase current control is achieved.Simulation and experimental results show that: TPOW-PMSM can run smoothly under the two kinds of reconstruction topology.So the correctness and validity of the proposed control strategy is verified.Finally,the system's high power factor and harmonic suppression technology for two parallel three-phase PWM rectifiers are studied under charging mode.The equivalent average model is established,the influence of system parameters on the zero sequence circulation is fully analyzed.The dual-loop control system for output current balance and circulation current suppression is designed.The feedforward decoupling control strategy of current loop is proposed,which can achieve unity power factor.A common voltage PI regulator in outer voltage loop is used to achieve output current balance control.Based on adjusting zero vector principle,a seven-stage symmetrical SVPWM control strategy is presented.The PI zero sequence current suppressor is designed,and an improved minimum beat zero sequence current suppressor is proposed,the influence of unbalanced inductance parameters of two parallel PWM rectifiers is suppressed effectively.According to the simulation and experimental results,the improved strategy of minimum beat circulation suppression can effectively suppress circulation,eliminate the interference of inductance unbalance on the system.Thus the output current balance control and circulation current suppression of the two parallel three-phase PWM rectifiers are achieved.