Switching Frequency Control for a ΔΣ-PWM

In 2014 Homann and Schumacher presented a new PWM-modulator (ΔΣ-PWM). This hysteresis based modulator allows to fully utilize the advantages of the delta sigma signal processing (DSSP). Because of the hysteresis based switching cycle of the ΔΣ-PWM one main feature is a variable switching frequency. In this paper a method for controlling the average switching frequency is presented. In order to guarantee a lower PWM frequency boundary, an frequency guard is presented. The paper finishes with an experimental verification of the presented PWM frequency controller and frequency guard.