Research On Drive And Control Technology Of Five-phase Permanent Magnet Synchronous Motor For Electric Vehicles

Due to the serious environmental pollution and energy shortage,electric vehicles(EVs)have received ever-increasing concerns with its advantages of zero pollution and low noise.Motor and its driving system are the key part of the EVs.Interior permanent magnet synchronous motors(IPMSMs)become the preferred choice for the new generation of EVs because of their characteristics of small volume light weight,high power density,high efficiency and wide range of speed.Five-phase IPMSM researched in this paper has became an advanced research hotspot since it can help to realize high power drive,improve overall system reliability and reduce the output torque ripple.Firstly,the background and significance of this thesis are introduced.Also,the development status of multi-phase fault-tolerant machines,flux weakening control and stator winding inter-turn short circuit fault for the five-phase permanent magnet motors are stated.In addition,the structure,principle and characteristics of the five-phase IPMSM are analyzed.Furthermore,the topology of the five-phase IPMSM driving system is designed and the mathematical model under the five-phase stationary coordination and two-phase rotating coordination is built.Secondly,the flux weakening control strategy based on DTC for the five-phase IPMSM driving system is studied.And this proposed strategy can achieve the goals of suppressing the third harmonic,constant torque operation under the base speed and constant power operation above the base speed.Also,the flux weakening control strategy based on SVPWM is researched.The closed four vectors are chosen to build the modulation module.With this proposed control strategy,the five-phase IPMSM could output the biggest torque at the low speed and obtain the wide range speed.Additionally,the motor's operating performance of DTC and SVPWM based on the proposed flux weakening control strategies are compared.Thirdly,the stator winding inter-turn short circuit fault and the corresponding mathematical model are analyzed.The error between estimated and actual torque is used to detect inter-turn short circuit fault.Simulation and experimental results have verified the efficiency and validity of the diagnosis method under dynamic state and fault conditions.Then,for the inter-turn short-circuit fault,the diagnosis method based on zero-sequence current is put forward.The relationship between zero-sequence current,the resistance and turn ratio is used to establish the diagnosis strategy.Hence,the fault severity could be estimated.Furthermore,the research has been carried out to reduce torque ripple when inter-turn short-circuit fault happens.And the fault current compensational method is proposed,in which the estimated result was used to establish virtual fault phase in the feedback loop.Finally,the system simulation model is established by Matlab/Simulink,while the experimental platform is developed based on controller dSPACE 1104.The strategies for flux weakening control,detection and analysis of inter-turn short circuit fault and suppression of torque ripple have been verified by numerical simulations and experiments.