On dimensioning the fundamental brick for a scalable DC-DC converter with energy recovery

For the design of a power converter with energy recovery operation, a trade-off is related to the choice of the output and dc-link voltages, which, in turn, determines the choice of the blocking voltage capability of the semiconductor switches. This work investigates the possibility to optimise the capital and operation costs and the performance (ripple) globally for a farm of 350 converters by considering the voltage rating and device type of a fundamental brick used in these modular converters. It is shown how considering the purchasing and operating costs separately can yield in different conclusions. It also highlights the effect of high precision requirements on the converter scalability and final cost. This paper investigates the design of the fundamental brick and optimisation possibilities for such converters in terms of cost, efficiency, reliability and precision. Another important design and operating requirement for a converter is to deliver the required current in a large range of loads, such as electromagnets. In order to keep the maintenance cost low and components availability high, it is desirable to have only one solution for a given converter design. The optimal converter size from the perspective of a large converter farm, could be different from the design of an individual converter, or indeed if the optimisation focuses on cost, efficiency, reliability or precision.