DC outlet using a multi-output current resonant converter

In order to charge electric devices such as laptop PC and smart phone without using AC adapters, a simple and low cost DC outlet using a multi-output current resonant converter is proposed. In this method, three level voltages of 5V, 10V and 20V are simultaneously provided in parallel to the DC connector pins. Due to the input terminal of the receiving electric devices only has the desired voltage pins, the desired voltages can be provided without the intercommunication control between the charger and receiver. Moreover additional multiple outlet taps are available for charging the several electric devices in the same way as AC outlet. A laboratory prototype of the multi-output current resonant converter was tested, and then maximum efficiencies of 94.7% at 20V, 92.4% at 10V and 85.8% at 5V are realized within an allowable voltage range of +/-10%.