An Improved Current Gradient Sensorless Scheme of Switched Reluctance Motors Based on Double Feature Point Position Detection

The Current Gradient Sensorless (CGS) scheme is often an ideal choice for low-cost sensorless drives of Switched Reluctance Motors (SRMs). Typically, the negative-going zero-crossing point of the current gradient can be detected as a feature position. However, using a fixed position as a feature point can lead to errors in rotor position estimation. Therefore, this artical proposes an improved control strategy based on CGS scheme. First, an algorithm for calculating the feature point position with speed compensation is investigated to reduce the computational error of the position estimation. Then, an integrated control strategy is developed to accurately calculate the feature point position under different phase voltages. To enhance the reliability of sensorless control, a remedial feature point detection method based on extended phase excitation is proposed. Simulations and experiments conducted under various operating conditions have verified the proposed scheme. The improved CGS scheme has also shown good performance at different speeds and phase voltages.