A Flexible Position Sensorless Control of Switched Reluctance Motors Considering Both Embrace Design and Magnetic Saturation

Abstract

Precise estimation of position is essential in the control of switched reluctance motor (SRM). Traditionally, the intersection of the adjacent inductance can be utilized to estimate the rotor position, however, magnetic saturation brings about the variations of the intersection positon when the motor is operated at heavy load. To solve the problem, this paper develops a sensorless position estimation strategies considering the magnetic saturation and the embrace design. Firstly, the relationship between the embrace and the intersection position is fully investigated. At low inductance region, the intersection position is not sensitive to the saturation current when the embrace is small, thus, the typical specific position can be used as an update point for position estimation. Disparately, the intersection position is influenced by a great extent when the embrace is a bit larger, the relationship between the saturation current and the intersection position is necessary to be explored. At high inductance region, the intersection position is a function of the saturation current which is irrelevant to the embrace. Consequently, the sensorless control approaches can be chosen flexible according the characteristic of intersection. The rotor position estimation is achieved by employing six typical inductance positon without a requirement of additional positon sensor. The feasibility and validity of the proposed position estimation method is verified under the inertial operation, light load, heavy load, load mutation and high speed condition. Index Terms—Switched reluctance motors, position sensorless control, embrace deign, magnetic saturation.