속도제어기의 전류지령 변경 알고리즘을 적용한 IPMSM 저속 센서리스 제어

초록

Recently, IPMSM(Interior Permanent Magnet Synchronous Motor) has been applied in many fields because it can operate at high speed in addition to the unique advantages of permanent magnet motors. IPMSM can obtain torque both through magnet reluctance and from the permanent magnets themselves. However, AC motors such as IPMSM require accurate detection of the rotor magnetic flux using resolvers or encoders to produce precise torque, and research on sensorless operation to address this requirement has been actively conducted. When operating a sensorless permanent magnet AC motor, the magnetic flux position must be accurately estimated based on back-EMF. At high speeds, sensorless operation is relatively easy because the back-EMF signal is sufficiently large, but at low speeds, sensorless operation becomes challenging because the back-EMF signal is too weak compared to noise, which is a major problem in most sensorless controls. This paper proposes an IPMSM sensorless control method that applies the current command modification algorithm for the low-speed region of the speed controller. From the difference between the speed command and the filtered motor estimation motor angular speed (the output of the sensorless controller), the speed controller performs MTPA(Maximum Torque Per Ampere) control of d-q axis current commands in the synchronous reference frame. In particular, in the low-speed region, it is necessary to appropriately apply d-q axis currents in the synchronous frame (i.e., modify the current command) within the range in which the magnitude of the stator current satisfies the current limit. To implement this, we propose a speed controller current command modification algorithm, and verify its effectiveness through experiments.

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