Synergetic control for ultracapacitors based high dynamic converters

Ultracapacitors are electrical energy storage devices, which offer high power density, extremely high cycling capability and mechanical robustness. Recent technology improvements enabled ultracapacitors to be an interesting option for short-term high power applications, such as in industry, automotive and traction drives, regenerative energy systems, medical and telecommunication equipment. However, ultracapacitors offer voltage value at terminals which is almost directly proportional to their state of charge and therefore greatly dependent on the operating condition. A power electronic converter is then required to utilize ultracapacitors in the mentioned applications, and reliable converter topology as well high dynamic control technique should be chosen in order to best operate the ultracapacitor storage unit. In this paper the synergetic synthesis of controllers for a bi-directional half-bridge converter is proposed. Results from both simulations and experimental tests show that the synergetic controllers have faster dynamic behavior with respect to more traditional linear controllers, thus synergetic control theory is particularly suited to synthesize the controllers of power electronic converters for Ultracapacitors. The control laws have been implemented on a fixed-point 16-bits DSP from Analog Devices, whereas a 30 kW half-bridge converter prototype has been used to carry out the experimental testing activity.