Maximum Torque Per Ampere Control System Of Multi-Unit Permanent Magnet Synchronous Motor

In the fields of aviation and marine propulsion systems,electric vehicles,and microgrids,multi-unit motors have significant advantages in flexible power sharing control.However,the asymmetry of the mutual inductance between the units of the multi-unit motor changes with the power sharing.The motor performance under power sharing is affected by the accuracy of the model and the corresponding control strategy to a certain extent.For this reason,aiming at a multi-unit interior permanent magnet synchronous motor with a modular stator structure,this thesis proposes a maximum torque per ampere(MTPA)control considering the mutual inductance between the units under power sharing.The details are as follows.Firstly,in view of the special structural characteristics of the modular multi-unit permanent magnet synchronous motor,considering the change of mutual inductance between the units under power sharing in this thesis,the mathematical model of the motor is studied.Utilizing the characteristics of the electrical angles of all units in the same phase,the coupling effect of other units is converted and superimposed to its own unit,and the flux linkage equation of the unit motor is given.Meanwhile,the spatial classification method is used to simplify the inductance coefficient,the change law of the self-inductance and mutual inductance under the power sharing of the unit motor is deduced,and the mathematical model of the dq axis of the unit motor is established.Secondly,to realize the MTPA control,the derivation of the current vector angle and solution method of the unit motor are studies in this thesis.By analyzing the control system structure and the change characteristics of voltage limit ellipse of each uint under power sharing,combined with the mathematical model of the unit motor,the expression of the current vector angle of the unit motor is deduced.On this basis,considering the order and complexity of the solution,a method of fitting the sine and cosine function to solve the current vector angle is proposed,and the goodness of fit index is used to evaluate the model.Finally,the feasibility of the unit motor MTPA control algorithm is verified by simulation.Thirdly,for the MTPA algorithm of multi-unit motor under power sharing,a mathematical simulation model and a finite element joint simulation model are built.The operating performance under the power sharing of multi-unit motors is studied.The simulation results show that the proposed method reduces the phase current compared with i_d=0 control,and can realize the stable operation of the motor under power sharing.Finally,a multi-unit permanent magnet synchronous motor control system experimental platform is built.The hardware circuit of the modular inverter power supply and the software program of the TMS320F28379 dual-core controller are designed.The feasibility and effectiveness of the proposed MTPA method under the power sharing are verifies.