Design and implementation of vector-controlled induction motor drives using random switching technique with constant sampling frequency

Recent results have shown that random switching techniques reduce electromagnetic interference, annoying acoustic noise, and other undesirable effects. However, to incorporate random switching techniques into digital-controlled induction motor drives, it requires dynamic adjustment of the gains of controllers. This paper presents details of the design and implementation of induction motor drives using a new random switching technique. It is shown, and confirmed by experimental results in this paper, that the sampling frequency of inverter control is constant, and therefore it is not required to adjust the gains of controllers dynamically. The details of controller design of the random switching inverter-controlled vector drives are fully explored, including the controller design in the discrete-time domain and the effect of the random technique on the speed response. Moreover, the advantages and disadvantages of inverter-controlled vector drives using random switching techniques are highlighted by experimental results.