Suppressing Undesired Periodic Modes in a PWM-Controlled DC Drive by Sinusoidal Modulation of a Reference Signal

PWM-controlled power stage under several conditions are prone to the coexistence of several stable modes for the same set of parameters. For the majority of applications, it is an undesired behavior; the other modes apart from the “nominal” one are characterized by lower efficiency and should be avoided. We propose a control aiming to suppress the coexisting undesired modes by utilizing periodic sinusoidal modulation of a reference signal. We study the efficacy of the proposed control strategy for different modulation strength levels with a chopper-fed DC drive as the case example of a PWM-driven system exhibiting multistability. The study is performed by means of numerical simulations in the time domain and bifurcation diagrams. The possible pitfalls and features of the proposed control are demonstrated.