Microcomputer Control of Power Converters

Thyristor power converters are charac terized by an inherent discrete control action and are, therefore, particularly well suited to on-line control by microcomputers. The paper presents a new design of digital controllers based upon powerfull 16-bit or bit-slice microprocessors, which provide high firing time resolution and enough computing power to implement sophis ticated control strategies. Both hardware and software are discussed, with special emphasis on the firing con trol algorithms. The properties of Pulse Frequency Con trol (PFC) and Pulse Phase Control (PPC) are examined and small-signal discrete models are presented. These models are used in the analysis of constant current and constant extinction angle control through the z-transform method.