A low cost DSP-based control method for high frequency parallel resonant current-fed inverters

Nowadays the possibility to increase switching frequency in power converters has allowed minimizing their size and weight, and has permitted the improvement of their power density. This has been achieved by using soft-switching techniques that reduce the switching losses and the stress the switches suffer, quite of this techniques rely on resonance concept. However this increase of frequency is not exempt of problems, and depending on the frequency it carries some problems in current sensing methods and in control precision. In order to solve these problems with an acceptable cost, a low-cost DSP-based control technique for current-fed parallel resonant inverters is presented. This technique uses gate signals as current measurement and the capture modules provided by most of microcontroller manufacturers. Such method decreases the cost, diminishes the analog components and its variability and improves the flexibility of the system. This technique is presented and applied to a 75 kHz and 6 kW prototype, obtaining favorable experimental results and demonstrating its feasibility.