Reducing the Common-Mode Currents at the Input and Output Sides in Non-isolated DC-DC Conveters

Various common-mode (CM) noise reduction techniques have been presented in Chaps.  7 – 9 , which reduce the CM current at the input power lines of DC-DC converters. However, the CM current at the output side should also be addressed, as it can affect the normal operation of sensitive loads, such as the devices with touch screen. Therefore, it is necessary to reduce the CM currents at both the input and output sides. In this chapter, the CM noise model of the buck converter is derived by considering both the input and output CM impedances. Based on this model, the split-winding (SW) method for reducing the CM currents at both sides is investigated. Then, the application of the SW method in other basic non-isolated DC-DC converters is discussed. Finally, the prototypes of the buck converter with and without the SW method are fabricated and tested in the lab. The measured CM currents at both sides are provided to verify the effectiveness of the proposed SW method.