Design of low output voltage DC-DC converters through artificial evolution

This paper describes the application of evolvable hardware to the design of a widely-used power electronics device, comparing the automatically synthesized circuits with those designed using the latest conventional design methods. With the increasing need by digital devices for low voltage and high current battery-driven power supplies, considerable research effort in recent years has been spent on high-efficiency DC-DC power converters. The best solution so far has been the use of control-driven synchronous rectifiers in these converters, which can yield efficiencies in the range of 91 to 92 percent. It is possible, however, that other designs could be found which might result in even higher efficiencies, with lower voltage and higher current outputs. Since the mid 1990's, the use of evolutionary algorithms to design a variety of hardware systems has seen rapid and successful growth, frequently resulting in novel designs not possible by conventional design techniques. In an exploratory experiment we will apply evolutionary methods to design a high efficiency, low voltage, high current output DC-DC converter. The performance of this evolved design will be compared with that of the control-driven synchronous rectifier converter, designed using conventional electronics design methods. While evolutionary design will not remove the fundamental design challenges, it is hoped that improved design approaches will emerge from the experiments. The paper explains why achieving high efficiencies in low output voltage DC-DC converters faces fundamental problems. A variety of solutions developed in the last 20 years are examined. Then the development of evolutionary processes starting in the 1950's is described. The invention of the field programmable gate array (FPGA) in the 1980's enabled extension of the evolutionary process to hardware design. Following this section, the need for and invention of hardware platforms more suitable for hardware evolution than the FPGA is reviewed. The series of experiments which is the objective of this paper is described, followed by comparisons which will be made between evolved and conventionally designed low voltage output DC-DC converters. The comparisons will be based on: maximum achieved efficiency; number of runs required to evolve to maximum efficiency; complexity of required hardware circuits; and other parameters found to be important as the experiments are performed. Sufficient details of the hardware and software used, and a complete list of references will be given, to enable duplication of the experiments and results by other independent research workers. On completion of the experiments, results will be analyzed and conclusions drawn as to whether the use of evolutionary design methods result in advantages over conventional design techniques.