2017 Volume 6 Issue 1 Pages 36-45
This paper proposes a position sensorless control system for interior permanent magnet synchronous motors (IPMSMs) within the inverter over-modulation range. In general, using the position sensorless control method in the middle- and high-speed regions requires q-axis inductance, which varies significantly owing to magnetic saturation. Therefore, parameter mismatch may occur, which decreases the motor efficiency and causes control system instability. Furthermore, in the inverter over-modulation range, the performance of the auto current regulator deteriorates significantly because disturbance components, which consist of low-order harmonic current components, are fed back to the controller. As a result, the operation range is not appropriately expanded if no measurements are obtained for these components. First, the robustness against magnetic saturation is increased by constructing a position sensorless control system based on the Ld model. Next, a comb-filter-based harmonic current countermeasure method is proposed. The position sensorless control system can expand the operation range in this method. Finally, the effectiveness of the proposed control system is confirmed by several experiments.