A Low Noise Peak Delta-Sigma Modulated DC-DC Converter with Utility Frequency AC Rectified Voltage Source

For the purpose of reducing power loss of power converters, switching power converters are generally used. High frequency operating power conversion realizes small size and lightweight converters. And high frequency switching power converters enlarge new application spheres like mobile equipments. As for the switching power converters, pulse width modulation (PWM) method is generally used. But in case of applying PWM method, switching noise peaks arises on the multiple number of the carrier frequency, and this induces difficulty on clearing noise regulations. To reduce switching noise peaks, delta-sigma modulation scheme has been proposed. But when applying this pulse modulation method for dc-dc converters, switching noise peaks appear like a PWM converter. By the way, dc-dc converters with ac rectified input power source are widely used. Focusing rectified voltage input type dc-dc converter, this paper presents a low noise peak delta-sigma modulated power converter. This proposed converter improves delta-sigma modulation circuit. And it is confirmed that the proposed converter can alleviate switching noise peaks and also effectively suppresses ac rectified ripple component at the dc output side.