Robust digital control of plus and minus DC power supply

A plus and minus DC switching power supply is needed for many applications, for example audio power supply. Since the loads of such power amplifiers are changed largely, the output voltage of the power supply are changed largely. Usually, in order to suppress the change, a capacitor with large capacity is used at the output end. If the capacities are made smaller, the power supplies can be compacted. In this paper, it is shown that the capacities can be made small using a robust digital control using an approximate 2DOF. The derived controller is actually implemented on a DSP. It is demonstrated from experiments that the power supplies can be compacted by the robust controller.