Research On High Performance Multi-Mode Motor Drive Technology Based On TSPWM

With countries attaching great importance to environmental and energy issues,research on pure electric vehicles will become a breakthrough to alleviate the energy crisis and improve the environment because of their advantages such as no pollution and zero emission.As the core component of electric vehicle drive system,the control technology of electric motor is also receiving more and more attention.The conventional space voltage vector pulse width modulation(SVPWM)technique generates high-frequency alternating common-mode voltage at the motor input,which is the main cause of shaft voltage.Under the action of shaft voltage,the shaft current damages the motor bearings and jeopardizes the normal operation of the motor.The pulse width modulation(PWM)switching frequency used in general inverter speed control systems is fixed,but due to the wide speed range required by the motor,the fixed switching frequency modulation method will cause unnecessary switching losses at low motor speeds and affect motor efficiency.To solve the above problems,this paper firstly analyzed the causes of common mode voltage generated by traditional SVPWM methods,and studied the principle of reducing common mode voltage using three state pulse width modulation(TSPWM)methods;Secondly,the TSPWM method was optimized to further reduce switching losses by PWM clamping the phase where the maximum current was located;Subsequently,based on the algorithm,a multi mode strategy using segmented asynchronous modulation was proposed,which used different switching frequencies at different speeds,and adopted a carrier cycle angle compensation switching method to switch between different modes;Next,a simulation model of permanent magnet synchronous motor based on TSPWM and a multi mode strategy switching model were established using MATLAB/Simulink,and the feasibility of the multi mode strategy based on TSPWM was verified through simulation.Completed the design of the underlying drivers such as the EPWM output module and the current acquisition module in the CCS development environment;Using automatic code generation technology to generate upper level control strategy code and integrated it with lower level drivers;Developed the hardware of the controller,including power supply circuit,crystal oscillator circuit,current sampling circuit,controller area network(CAN)communication circuit,and temperature sampling circuit;In the PLECS software,thermal simulation models of electric motors using fixed carrier frequency SVWPM and multi mode TSPWM as control modes were established to analyze the impact of the two control modes on the efficiency of the inverter.A motor experimental platform was built,common mode voltage was tested,and the maximum current phase clamping measures and angle compensation switching method based on carrier period were verified.The results showed that the TSPWM method could significantly reduce the high-frequency common mode voltage of the motor;The maximum current phase clamped TSPWM algorithm further reduced the switching loss of the inverter compared to the original TSPWM method;The switching method based on carrier period angle compensation could ensure smooth switching between different modes.An inverter efficiency test experiment was conducted on fixed carrier frequency SVPWM and multi mode TSPWM strategies.By comparing the inverter efficiency obtained by the two control methods,it was verified that the multi mode TSPWM strategy proposed in this paper could significantly improve the inverter efficiency of the drive system,meeting the expected goals.