Frequency- and Mode-Adaptive Control of DC-DC Converter for Efficency Improvement

It is common practice to operate Two-Quadrant-Converters with a constant switching frequency. However, the loss-optimal switching frequency strongly depend on the operation point thus for most operation points the selected frequency leads to higher losses than necessary. This paper presents a derived loss model which can be used to find the loss-optimal switching frequency. The presented model is easily computable on todays DSPs, thus allows frequency adaption on the run. A lab-prototype was built in order to verify the performance enhancement enabled by the proposed model. Experimental results are presented which show an efficiency improvement of approx. 1%.