Contributions to Discrete-Time Sliding Mode Observers for Permanent Magnet Synchronous Motor Drive Systems

Sliding Mode Observers are a mature technology and widely employed in sensorless motor drive systems. However, most of the content available in the literature deals with continuous-time observers and some details of them are not properly addressed. This paper presents contributions to the discrete-time sliding mode observers for permanent magnet synchronous motor drive systems. The sliding mode observed covered in this paper is based on the Sigmoid function instead of Sign function, thus reducing the problems of chattering. Details of this function are carefully explained in discrete-time framework. Besides that, this papers describes discrete-time differentiators and integrators with superior performance over the conventional ones, since these functions play an important role in the system performance. Case studies with hardware-in-the-loop tests are conducted to show that the contributions of this paper can help designers to employ observers for motor drive systems in a straightforward manner.