A heuristic digital control method for optimal capacitor charging

A digital control method for optimal capacitor charging was developed and tested by simulations and experimentally. The control algorithm follows the concept of first searching for the optimal charging conditions of the given power stage and then using the collected data in the free running operation. The major advantage of this control approach is that it eliminates the uncertainty due to parameters variations and that it can be applied to any type of capacitor charger configuration by setting the desired charging profile objectives. The method is demonstrated on a piezoelectric transformer based power stage that behaves like a resonant converter. To further increase the accuracy of the control for this resonant converter case, we applied a frequency resolution enhancement algorithm that allows fine tuning of the drive. Excellent agreement was obtained between the analytical derivations, simulations and experimental results.