Implementation of sensorless vector control for super-high-speed PMSM of turbo-compressor

This paper describes the implementation of two vector control schemes for a variable-speed 131-kW permanent-magnet synchronous motor drive in super-high-speed applications. The vector control with a synchronous reference frame current regulator was implemented with challenging requirements such as an extremely low stator inductance (28 μH), a high DC-link voltage (600 V), and a high excitation frequency (1.2 kHz). Because the conventional position sensor is not reliable at super-high speed, two different schemes were proposed to measure the position of the rotor. As a first step, a vector control with three discrete Hall sensors was proposed. Because the discrete Hall sensors provide rough position information with a resolution of ±30°, a position estimation algorithm was proposed to derive the precise position. Subsequently, a vector control scheme without any position sensor was proposed. The proposed sensorless algorithm was implemented by processing the output voltage of the proportional plus integral current regulator. Therefore, the structure is simple and the estimated speed is robust to the measurement noise. An experimental system was built and the proposed control was implemented and evaluated with and without the discrete Hall sensors. The test results, up to a speed of 65000 r/min, confirmed the validity of the proposed control.