High performance autotuning switching power supply

This paper presents a new digital control method for a buck-boost converter. This new autotuning digital control is composed of “changing gain” and “changing bias”. The changing gain improves the transient response and the changing bias eliminates the steady state error. In the proposed method, the gain of FIR filter changes automatically along with the phase margin. The bias value also changes depending on the input voltage and loss of the converter. The steady state error and convergence time of buck-boost converter are improved when the input voltage changes 50%. In this paper, the digital IIR filter with autotuning method to obtain the further improvement on the dynamic characteristics, and then it is confirmed that this proposed method achieve superior transient response to existing proposed method using FIR filter. The proposed digitally controlled buck-boost dc-dc converter is suitable to the automotive applications since it shows a superior transient performance against wide input voltage range.