Multiphase dc-dc converter with high dynamic performance and high efficiency

This study presents a novel voltage mode digital controller and a multiphase dc-dc converter with non-uniform current sharing to minimise the power consumption during stable load and very light load operation. To minimise the power consumption and provide fast dynamic response, a low-frequency phase is in parallel with a bi-directional high-frequency phase. The digital controller operates on a modification of the -phase dropping- principle. Depending on the speed of output load change, the bi-directional high-frequency phase will be activated, providing fast dynamic response, while a low-frequency phase is working all the time. The digital controller uses a look-up table control method, which is quite flexible and suitable for multiphase converters with phases switching at different frequencies. An experimental two-phase buck converter utilising the digital control method has been built. A comparison of the efficiency and dynamic performance between the high-frequency phase, low-frequency phase and multiphase has been made. In addition, the dynamic performance of the look-up table control methods has been compared with proportion integral and differential (PID) control method, and the efficiency of the multiphase converter has been compared with another phase drop method which is commonly used in previous works.