Digital Power Conversion System based on a Sigma-Delta Modulator Linear Model

This paper presents a new linear model for the Sigma-Delta (ΣΔ) modulator, based on modeling the nonlinear quantizer with a linear factor, and its input-to-output transfer function is given. The use of a 1-bit Sigma-Delta modulator in dc/dc power converter systems permits to implement a complete digital control. Results of an investigation from a prototype for a DC-DC converter are here reported. Using of a field programmable gate array allows implementing a simple variable control function. The modulator output produces a variable-frequency variable duty-ratio signal to control the switching power transistors.