Integrated Variable-Frequency and Phase-Shift Control for Low-Noise DC-DC Converters with Ripple Current Optimization

Low-noise switching controls have been proposed for a power converter circuit. However, the noise reduction effect is strongly influenced by measurement conditions. This paper focuses on the relationship between the noise reduction effects and measurement conditions in the low-noise switching control for power conversion circuits and proposes a control that combines the variable-frequency and phase shift control. This paper presents the mechanism of influence of measurement conditions such as detection mode and resolution bandwidth on low-noise switching controls. A specific condition that makes noise reduction challenging is shown. Even under conditions where noise reduction is difficult, the proposed control can reduce noise at approximately 500 kHz by 6 dB. The parameters for switching waveforms are determined via theoretical calculations. The results of measurements conducted using a buck converter agree with the theoretical results. Additionally, for suppressing ripple current, the relationship between ripple current and parameters for switching waveforms is evaluated. This control enables the selection of parameters that can result in both noise reduction and ripple current suppression.