High-Precision Injection Current Sampling Scheme for Direct Drive Low-Speed Position Sensorless Control of Switched Reluctance Machine

In cost-sensitive applications, the controller usually creates great noise that affects the current sampling accuracy. In this article, based on the conventional direct drive low-speed position sensorless control of switched reluctance machine (SRM), a high-precision injection current sampling scheme is proposed to improve the current sampling accuracy and thus the commutation position accuracy. First, the errors in the conventional current sampling are analyzed quantitatively. Second, aiming at reducing the current sampling noise, a dual-channel current sampling circuit is proposed to improve the current sampling accuracy. Third, a pulse current peak value prediction method based on the curve intersection method is proposed, so the error caused by discrete sampling can be reduced. Finally, the experimental setup is established and experiments under both the steady-state and transient-state are conducted, which demonstrate the feasibility and accuracy of the proposed method.