A Speed Sensorless Vector Control for Permanent Magnet Synchronous Motors Based on an Instantaneous Reactive Power

초록

The mechanical information such as the rotor speed and angle is required to control the speed of the cylindrical permanent magnet synchronous motor (PMSM). A resolver or encoder is typically used to supply the mechanical information. The position sensor adds length to the machine, raises system cost, increases the rotor inertia and requires additional devices. As the result, there has been a significant interest in the development of sensorless strategies. To eliminate the position sensor, this paper proposes an implementation of the new sensorless speed control scheme for a PMSM. In the proposed algorithm, the line-currents are estimated by a observer and the estimated speed can be yielded from the voltage equation because the information of speed is included in back-emf. But the speed estimation error between the estimated and the real speed is occurred by errors due to measuring motor parameters and sensing line-currents and input voltage. To minimize the speed estimation error, the estimated speed error is compensated by the instantaneous reactive power. Because parameters of the mechanical equation such as machine inertia or a viscosity frition coefficient are not well-known, there are many restrictions in the actual implementation. In the proposed algorithm, the mechanical equation is not used. Therefore, the algorithm is constructed easily.