Research On Drive System And Control Method Of Hybrid Excitation Synchronous Machine For Electric Vehicles Application

Drive motor is the core technology of electric vehicle(EV),which directly affects the operatingperformance of EVs. Recently, permanent magnet synchronous machine (PMSM) has becomeresearch focus of EV drive motor for its high power density and high efficiency. Hybrid excitationsynchronous machine(HESM) combines the merits of PMSM and electric excitation sychronousmachine (ESM), possessing the characters of strong flux-weakening capability and less rare earthpermanent magnetconsumption compared to PMSM, which has significant importance for the studyof HESM drive system and control strategy.According to the structural features and operational principles of the new HESM with magneticshunt rotor, in-depth research and analysis of the mathematical model, vector control strategy andexcitation current control strategy of the HESM is conducted. Zone control strategy for excitationcurrent is presented based on the vector control strategy of id=0. Constant excitation current is appliedto make the HESM work in the flux-strengthening operating state at low speed to maintain hightorque output and improve the dynamic response ability of the machine. Excitation current isregulated to realize flux-weakening operating state according to the speed signalvariation of themachine at high speed which do not requires direct axis demagnetization current and therefore has norisk of permanent demagnetization. Simulation model of the HESM drive system is established inMatlab/simulink to study influences of excitation current on dynamic and steady performance of theHESM. Simulation results verify the merits of low speed high torque and wide speed regulationrangeof the HESM with magnetic shunt rotor.A HESM with magnetic rotor of24kW rated power and4600rpm rated speed is studied in thepaper. The hardware structure and software program of the HESM drive system is designed based onthe control principles of drive system and experimental tests of the system are accomplished.Experimental results show that the new drive system could realize a wide range of speed regulationthrough low power excitation current regulation which has significant importance in the study andapplication of EV drive system.