50 W Resonant SMPS with coreless transformer for AM radio application

Resonant converters are attractive in some applications, because of their soft-switching behaviour. The very low switching losses make them superior compared to traditional hard-switching converters. The present paper considers a 50 W resonant SMPS with coreless transformer for AM radio applications above the AM band (1.7 MHz), to avoid switching disturbances and radio signal interferences, where a half-bridge LLC/LLCC resonant converter topology is designed and realized together with a resonant gate driver. In this connection it should be mentioned that this paper deals with an unknown area, since the authors could not find any papers published, regarding coreless transformer for above-mentioned applications. The entire converter is simulated using PSpice. A comparison between simulated and realized system has been made, which showed an excellent agreement of the system with only few percent deviation. The experimental tests show that the realized converter has a high performance and efficiency up to 87.6 %. It is shown that with a DC input voltage range of 276-375 V, the output voltage is 15 V from 10 W to 50 W output power, except in no load. The output voltage ripple is 84 mV_pp and 114 mV_pp at 15 W and 50 W output power, respectively. In addition, a switching frequency from 1.9 MHz up to around 4 MHz is possible