Higher-order averaging for DC-DC converters

We revisit higher-order averaging and ripple computation for DC-DC converters in Continuous Conduction Mode, following the modern treatment of periodic averaging theory. We give a much simpler treatment of second-order averaging and ripple computation than usually found in the power electronics literature. We also extend it to third-order averaging, thus significantly improving the accuracy of the approximations, which is useful in particular when the switching frequency is not very high.