Research On Direct Torque Control Using Expected Voltage’s SVPWM Of Permanent Magnet Synchronous Motor In Electrical Vehicle

The development of new generation clean and energy saving vehicles like pureelectric vehicles has become an important way and inevitable trend which canresolve the problems of energy shortage and environmental pollution and achievesustainable development of the automotive industry.Permanent magnet synchronous motor （PMSM） has a high application value inthe field of electric vehicles because of its efficiency, high control accuracy,high torque density, low-noise and other characteristics. So it has been highly paidattention to.Direct Torque Control （DTC）, as one of the high-performance control ofPMSM, has been attracting widespread attention and in-depth study recently. Itsexcellent dynamic response and robustness of the motor parameters of DTC make itspecially designed to meet the operating environment and actual needs of electricvehicles. This paper will use DTC to control the main drive PMSM of electricvehicles, and do some research in the following aspects:Firstly, the structure and characteristics of PMSM is analyzed in order to givethe mathematical model of PMSM, then the theoretical basis of PMSM’s using onPMSM is investigated, inner link and essential difference between Direct TorqueControl and Vector Control of PMSM is pointed out.Secondly, the block diagram of traditional DTC is given and the model ofelectric vehicle is established based on detailed load characteristic analysis.Furthermore, traditional PMSM-DTC is simulated combining with car modeland operating conditions by tools of Matlab/Simulink.After that, the expected voltage vector DTC based on load angle incrementΔ δ_smsmis presented to overcome flux and torque ripple of traditional method. Thenexpected voltage’s SVPWM DTC based on flux and torque’s decoupling is used toimprove the former method. Simulation results combined with electric vehicleoperating conditions indicate that both its steady-state and dynamic performancehas significant improvement compared to traditional DTC. Finally, according to theoretical research and computer simulation which havebeen completed, an PMSM-DTC experimental platform including both hardwareand software has been designed and established with Freescale’s56F8345DSP asits control core. Program code has also been successfully written out anddebugged in a software developing environment named “Codewarrior”.