Characteristics of a New Series-Resonant Converter with a Parallel Resonant Circuit

Conventional series-resonant converters suffer from wide variations in conversion frequency during constant voltage regulation, resulting in audible noise under light-load conditions. A new series-resonant converter has been developed in order to eliminate this problem. The converter uses a parallel resonant circuit with a resonant frequency of over 20 kHz installed in series with the load circuit. The output voltage is thus regulated by varying the conversion frequency in a higher area than that of a conventional series-resonant converter. An efficient, lightweight small-sized rectifier is developed using this new series-resonant converter. The rectifier unit can convert 200-volt AC to 48-volt DC and is capable of supplying an output current of 30 amps. Efficiency for 50 to 100% output current is 92%. The new rectifier is also free from any audible noise.