Abstract
This paper proposes a new generalized heterodyne method that incorporates a high-frequency integral-type phase-locked loop (PLL) as a versatile rotor-phase estimation method from stator current caused by high-frequency voltage injection for sensorless drive of salient-pole permanent-magnet synchronous motors. The proposed method has the following characteristics that are in direct contrast to those of conventional heterodyne methods. 1) In principle, it can be applied to almost all voltage injection methods. 2) In principle, it can properly estimate the rotor phase over a wide range of speed. 3) It employs a new simple estimation structure based on the high-frequency integral-type PLL method, which does not require any additional filters. 4) An analytical method for designing the components of the structure has been established and no trial and error method is required for selecting the parameters for the components. 5) The stability of the phase-estimation system of the structure is guaranteed. 6) The high-frequency noises generated in the heterodyne process do not appear on the estimated rotor phase.
