Clarification of no-load loss in DC-DC converter

To improve the efficiency of DC-DC converters, this paper focuses on air-core reactors. First, the author deduces the relation between load loss and no-load loss, which originates from ripple current. Next, the author tests a reactor regarding the increase in temperature by changing the waveforms and frequencies under the same cooling and rms current conditions that enable the separation of the DC and AC losses. The results regarding the increase in temperature are different and demonstrate the existence of AC loss in the air-core reactor. It is determined that the AC loss is the eddy-current loss by a finite element analysis. Finally, this paper calculates no-load loss in the DC-DC converter. The AC loss, which consists of eddy-current loss, accounts for more than 90% of the no-load loss. From the results, this paper refers to the importance of the reduction in ripple current in the reactor.