MTPA based V/f Control of Surface PM Synchronous Motor by Direct Control of Voltage Vector without Current Feedback

In conventional method, maximum torque per ampere control (MTPA) of PM synchronous motor (PMSM) is realized by controlling d-q axis stator currents. In this work, MTPA control is achieved by direct control of stator voltage vector, which eliminates the need of d-q current control. For this MTPA is realized in voltage vector plane which provides MTPA condition in terms of stator d-q axis voltages. The stator voltage vector amplitude is evaluated based on MTPA condition. Phase angle of stator voltage vector is determined from the torque reference considering a linear relationship with torque and phase angle of the stator voltage vector. The key advantage of this technique over the conventional MTPA technique; any type of current control is not required. This makes the structure of proposed MTPA control scheme similar to V/f control. Therefore, the complexity and cost of the drive is reduced significantly. However, performance is comparable to conventional MTPA control and better than existing V/f control. Presented simulation and experimental results establish superior performance of the drive.