Research on the Technology of Power Adapter Without Input Electrolytic Capacitor Based on One-Cycle Control

High power density is the key to power adapter miniaturization, and it is also one of the research hotspots of the power adapters. Aiming at the problem that the input electrolytic capacitor affects the volume of the power adapter, a topological structure of the power adapter without input electrolytic capacitor is proposed in this paper. This topology adds an energy compensation loop based on the flyback converter. The balance between input instantaneous power and output power is realized by controlling the charge and discharge of the energy storage capacitor in the energy compensation loop to reduce the low output voltage ripple. The working principle and switching mode of the topology is analyzed in detail, the key parameters of the circuit are designed for the proposed circuit topology, and a control strategy for the circuit topology based on one-cycle control is proposed. Finally, the circuit topology and control principle is verified by simulation at 60W. The simulation results show that the proposed circuit scheme can reduce the output voltage ripple to less than 0.3% at 60W, and eliminate the input electrolytic capacitor, which greatly reduces the volume of the power adapter.