Research On Implementation Method Of Maximum Torque Per Ampere Control Strategy For IPMSM Drive System

The market of new energy vehicles industry has gradually expanded since 2010.To meet the torque demand during start-up and acceleration of new energy vehicles using IPMSM drive system,Maximum Torque per Ampere(MTPA)control is required.Therefore,it is necessary to conduct an in-depth study on the implementation method of MTPA.In order to achieve an efficient MTPA control under variable parameters,it is necessary to simplify the MTPA trajectory and expressions since the inductance and permanent magnet flux linkage of IPMSM constantly change by magnetic saturation and temperature rise.This thesis firstly analyzes the fitting method of MTPA control trajectory,and calculates the output characteristics of the conventional polynomial fitting method.Aiming at improving efficiency problems for polynomial fitting method at large current amplitude,a new method is proposed in chapter 2 using asymptote of MTPA trajectory.And the engineering solution of the optimal switching current of these two methods is given.Secondly,this thesis argues that the nonlinear effects is caused by using Is and iq as input of MTPA model,thus causing the change of dynamic performance of IPMSM control system.To solve this problem,this thesis presents an easy correction scheme.The transfer functions and gain functions of the MTPA model is deduced and simulation is made to support this argument.At last,MATLAB simulation based on EKF on-line parameters estimation is made to verified the proposed methods and experiments using TMS320F28335 platform is conducted to support the aforementioned argument.