Resonant Switching and Power Control of DC-DC-Converters with a Variable Transmission Path

摘要

A new control strategy for the detection of the resonant frequency of a DC-DC converter with a variable transmission path is used in this paper. Applying a Second Order Generalized Integrator (SOGI) in combination with a Frequency Locked Loop (FLL), the primary current of the transmission path is filtered and the orthogonal signal is determined. With the two outputs the current phase angle can be calculated and the correct switching time is determined by compensation of the signal propagation delay. Based on this approach a continuous adaption of the dead time between two complementary control signals for the full bridge is proposed. The importance of the correct dead time is proven by measurements. Furthermore, a new algorithm for power regulation is introduced. Improving the state-of-the-art energy injection and free-oscillation method, the power transmission can be enhanced and the switching frequency might be reduced for low power.