Research On Control Strategy Of Open Winding Hybrid Permanent Magnet Material Brushless Motor

In recent years,serious environmental pollution and energy crisis have made people pay more and more attention to environment and energy issues.The new energy vehicles led by electric vehicles are of great significance in mitigating the energy crisis and protecting the environment,and are an inevitable trend in the development of the automobile industry.The motor drive is the core of the electric vehicle’s electric drive system and is essential for the high-performance operation of electric vehicles.With the increasing demand for the performance of electric vehicles,the power required by motor drive system is increasing,which makes it develop towards high voltage and high current.For the drive motor of the vehicle,the battery capacity is limited by the safety of the car and the space of the electric vehicle,which limits the range of the motor speed to some extent.The common DC bus double inverter open winding motor topology requires only one DC power supply,which is more conducive to improving the output power and widening the motor speed running range under the premise of limited battery capacity of the electric vehicle,which is in the motor drive system.However,it has zero-sequence current loop,which causes zero-sequence voltage to produce zero-sequence current,which leads to the increase of motor loss and the decrease of system performance.In this paper,hybrid permanent magnet material brushless excited by rare earth materials and non-rare earth materials is taken as the research object.The modulation mode of the driving system of the open-winding motor with common DC bus is studied,which can make the driving system not only have a wider output voltage range,but also have a smaller zero-sequence voltage in the full output voltage range.First of all,the rotor and stator structure of the new HPMM-BL is introduced.And the mathematical model of the open-winding HPMM-BL motor with common DC bus in three-phase static coordinate system and two-phase rotating coordinate system is deduced.The zero-sequence voltage and zero-sequence current problems existing in the open-winding structure with common dc bus are pointed out.Secondly,the topology of the open-winding motor system and the space voltage vector of the double inverters are introduced.Then middle hexagon PWM,alternate sub-hexagonal center PWM(ASHC-PWM)and decoupling SVPWM of the open-winding motor drive system are studied.It is found that the single modulation strategy can not balance the voltage output range and zero-sequence voltage,and it is verified by simulation.A phase-shift decoupled SVPWM control strategy is proposed in this thesis.Based on decoupling SVPWM,the proposed strategy takes the phase angle between the two voltage vectors as a control variable.By shifting the phase angle,the OW-PMSM can achieve wide output voltage range and smallest zero sequence voltage during the full output voltage.Finally,the correctness and validity of the proposed method is verified by simulations and experiments using MATLAB/Simulink and the experimental platform based on dSPACE DS1007.