Analysis of favored design frequency of high-frequency transformer with different power capacities

High-power high-frequency transformers will become important electrical components in future DC/DC converters of HVDC power transmission system. Flux density and working frequency are mainly the most two important parameters in transformer design process. According to the design method of transformers, the design size and weight of transformers will decrease significantly with the increase of the operating frequency. However, it does not mean that increasing the operating frequency of transformers can infinitely reduce the size of the transformer. Different working frequencies mean different transformer sizes, which are closely related to the costs of transformers. In the relatively low frequency level, the design size of transformers can reduce as the operating frequency increases, but when the frequency reaches a certain level, the design size of transformer cannot decrease anymore as the losses and temperature rises become so large that the transformer cannot work well enough, this frequency level can be called favored transformer design frequency. Under different working flux densities and capacities, this paper designs high-frequency transformers with different magnetic cores such as silicon steel laminations, amorphous alloy. After designing, it reveals that different core transformers have different favored transformer design frequencies, magnetic core with more outstanding loss characteristic and lower working flux density has a higher favored transformer design frequency. This paper also explains why high-frequency transformers generally choose lower working flux density and high frequency transformer with a certain power capacity exists a corresponding minimum design size, this conclusion may be very useful and practical in future high-frequency transformer design of DC/DC converters.