New PWM schemes based on the principle of equivalent areas

Abstract

It is shown that the concept of discrete-time models of an analog system can be applied to the principle of equivalent areas (PEA), which is noncausal in its exact form. The proposed method makes possible the development of various algorithms for implementing online the PEA for control purposes. From this viewpoint, the existing PEA as applied to the pulse-width-modulation (PWM) can be viewed as the case where the zero-order-hold is used. Moreover, with the proposed approach, an infinitely many formulae can be derived for the conversion of a servo signal into a PWM signal. Four such formulae are shown; two are single-rate formulae and the other two are dual-rate ones. These methods are compared numerically using an open-loop first order example.