A Novel Newton-Raphson-Based Searching Method for the MTPA Control of Pmasynrm Considering Magnetic and Cross Saturation

Maximum torque per ampere control (MTPA) takes full advantage of the reluctance torque aiming at the minimum copper loss, which can increase the torque output under the minimum current conditions. The traditional MTPA method makes use of equations with constant inductance values which are implemented as look-up tables. However, the inductances of the motor present both magnetic saturation and cross-saturation characteristics. Those parameters are changing depending on the operating point. This paper presents a novel MTP A control strategy of permanent-magnet assisted synchronous reluctance motor (PMaSynRM) implementing a Newton-Raphson-Based Searching Method for improving the control accuracy for optimal current reference. The proposed method eliminates the need of fitting operations due to the nonlinearity of the MTP A formulation and takes the inductance variation, due to magnetic saturation, into account. Finally, the effectiveness of the proposed method is verified by means of Matlab/Simulink simulations.