Predictive Flux-linkage Control For Novel Dual-Permanent-Magnet-Excited Machines

The Dual-Permanent-Magnet-Excitation(DPME)machine is developed on the basis of permanent magnet synchronous machine.Its stator and rotor are equipped with permanent magnets.Compared with the traditional permanent magnet synchronous machine,its special feature is that the pole number of armature winding is not equal to the pole number of rotor.Its core idea is based on the bi-directional magnetic field modulation effect.This method can effectively couple the magnetic field produced by permanent magnet and the magnetic field produced by armature windings.DPME machine can provide more powerful torque,which makes them more competitive in the field of low speed and large torque.Predictive control is a kind of intelligent control arithmetic rising in recent years.It can restrain parameter change and uncertain disturbance,and make the system obtain better control performance.Predictive flux-linkage control is to predict the flux-linkage of next moment in the control system and then control the machine.At present,there are few researches on predictive flux-linkage control.Based on the PI speed control of DPME machine,this paper introduces the predictive flux-linkage control algorithm and optimizes the cost function to overcome the shortcomings of the traditional vector control method,such as complicated parameter setting,and the control effect is greatly affected by the system parameters and uncertainties.Firstly,based on the principle and structure of DPME machine,this paper analyzes its characteristics in the process of operation,and deduces the mathematical model of DPME machine with coordinate transformation.The simulation results of JMAG Designer prove that the expressions of DPME back EMF and output torque are the same as those of traditional Permanent Magnet Synchronous Machine(PMSM).In this paper,the control block diagram and idea of traditional vector control and direct torque control are deeply analyzed.The basic principle of predictive control is introduced.The speed loop is PI control and inner loop is predictive flux-linkage control.At the same time,the relationship between torque and rotor position angle in predictive flux control is studied,and the cost function is optimized.The weight coefficient is eliminated,which makes the control strategy more concise and effective.The vector control model and new predictive flux-linkage control model of DPME machine are established in Simulink simulation.The simulation results show that the new predictive flux control is betterthan the vector control in both current and speed control performance and robustness when model parameters are mismatched.At the same time,Based on the dSPACE experimental platform,the non-load starting experiment and speed step experiment are carried out respectively,which verifies the effectiveness of predictive flux-linkage control applied to DPME machine.