Direct Torque Control Of Five-phase Interior Permanent Magnet Synchronous Motor Based On Signal-injection-MTPA

Interior Permanent Magnet Synchronous Motor(IPMSM)has attracted more and more attention because of its high power density,high torque density and wide speed range.At the same time,direct torque control has been widely applied in IPMSM drive systems because of its excellent dynamic performance.To maximize torque of IPMSM,maximum torque per ampere(MTPA)control can utilize the reluctance torque to reliaze the same output torque with the least current.Therefore,the drive system can be improved effectively.Aiming at the existing problems of MTPA control strategy,two improved MTPA control strategies of five-phase IPMSM-DTC control system are proposed,which solve the problems of poor anti-disturbance ability of flux signal entry method and extra disturbance introduced by signal injection method respectively.The main contents of this paper are as follows:(1)The mathematical model of five-phase IPMSM is introduced.The mathematical model of five-phase IPMSM in different coordinate systems and the transformation matrix between them are deduced.On this basis,The direct torque control of five-phase IPMSM and its improved algorithm are introduced.(2)In the five-phase IPMSM direct torque control system based on CPWM modulation,a MTPA control strategy based on rotating voltage signal injection is proposed.By directly injecting a high frequency sinusoidal signal into the reference value of the motor voltage vector,the motor operating conditions are tracked according to the relationship between the stator current amplitude and the stator flux linkage.This method injects the high frequency signal directly at the given voltage,which can inject the signal into the motor more accurately.Therefore,the proposed algorithm has better anti-disturbance ability.At the same time,the algorithm is simulated and analyzed to verify the correctness of the principle of the algorithm.(3)In the five-phase IPMSM direct torque control system based on improved switching table,MTPA control strategy based on virtual signal injection is proposed.By constructing the relationship between stator current amplitude and stator flux linkage,a virtual signal is injected to track the MTPA points during the operation of the motor(VSI-MTPA).This algorithm does not need to inject any actual signal,so it will not cause additional pulsation and harmonics.At the same time,the performance of the two algorithms is compared through simulation analysis.VSI-MTPA can track MTPA points without introducing additional perturbations,and has better dynamic response performance.(4)Based on dSPACE platform,a five-phase IPMSM driver and control platform is built.The composition of the drive and control platform is summarized,and the hardware circuit of the drive system is introduced in detail.Finally,for the VSI-MTPA algorithm,in order to verify the tracking accuracy and dynamic performance of the algorithm in practical application,relevant experiments are completed on this platform.