Figures of merit for the evaluation of regenerative power converters

In some applications, like those for particle accelerators and transfer lines, electromagnet loads operate in cycling mode i.e. absorbing or extracting energy from or to a power source. Built-in energy storage such as electrochemical capacitors can be used whose lifetime is heavily depended on the current ripple and depth of discharge. Moreover, the sizing of this storage element is a trade-off between power taken from the grid and energy stored. Additionally, the adopted power conversion structure and control strategy impact on such decision process. In this work, a number of topologies have been evaluated for these applications and the key metrics used to compare them. The proposed figures of merit are used through examples to highlight the trade-offs related with the choice of dc-bus regulation topology and control strategy.