This paper proposes a back electromotive force estimation error compensation method for accurate rotor position estimation of surface mounted permanent magnet synchronous motors. When estimating the rotor position of surface mounted permanent magnet synchronous motor sensorless drives, a direct current offset error component occurs in the voltage sensor. As a result, the rotor position is distorted and the sensorless control in surface mounted permanent magnet synchronous motor is degraded. In addition, the dq-axis voltages in the synchronous reference frame have the direct current offset error component, ripples compared with the motor frequency under the distorted rotor position. In this paper, the effects of the direct current offset errors are analyzed based on the synchronous reference frame phase locked loop. To remove this direct current offset error component, a d-axis voltage is converted into a synchronous reference frame again to compensate. In other words, it is a dual synchronous coordinate conversion compensation method. The compensator utilizes a proportional-integral controller that compensates by estimating the direct current offset error component. The proposed method is useful for the improvement of surface mounted permanent magnet synchronous motor sensorless control and operating performance. The effectiveness of the proposed algorithm is verified through PSIM simulation and experimental results.
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