Compact audio power supply using Approximate 2DOF robust digital control

A compact audio switching power supply for a car is needed. Since the output voltage change of an audio amplifier which is a load is large, the power supply voltage is changed largely. Usually, in order to suppress the change, a capacitor with large capacity is used at the output end. If the capacity is made small, the power supply can be compacted. In this paper, it is shown that the capacity 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 supply can be compacted by the robust controller.