Improve torque response using the inverter overmodulation range in position sensorless control system of PMSM

In this paper, a method of Permanent Magnet Synchronous Motor(PMSM) position sensorless vector control system in the inverter overmodulation range has been proposed. Operating PMSM in the inverter overmodulation range achieves fast torque response and widens high-speed drive region of PMSM. In the range, however, because of the effect from harmonic currents, a closed loop current control system become unstable further more because of harmonic voltage output from the inverter makes position estimation error and it destabilize sensorless control system. First of all describes mechanism of destabilization of sensorless control system in the overmodulation range. Second of all propose a method which stabilizes control system. Last of all the experimental results show that the proposed method widen high-speed drive region and archives fast torque response.