A novel current-slope estimation strategy for sensorless position control of IPMSM without high-frequency signal injection

This paper proposes a novel strategy of current-slope estimation for sensorless position control applicable to interior permanent magnet synchronous motors. First we show, according to different switching modes of a six-switch voltage-source inverter based on hysteresis current control, the relation between rotor position and current-slope can be derived from the three-phase stator-voltage equations and the stator-current balance equation. The current-slope difference signals can then be extracted from the three different active-voltage switching modes. Finally, through designed six coordinate transformation matrices and an inverse tangent function, the rotor position can be estimated. The advantages of the proposed method include enhancing the current-slope difference signal, not requiring high frequency signal injection, and not using the zero-voltage current-slope signal. Some simulation results are provided to show the effectiveness of the proposed method.