| 摘要 |
PROBLEM TO BE SOLVED: To provide an LLC series resonance converter which can achieve a light load voltage adjustment function utilizing a circulation current circuit.SOLUTION: An LLC resonance converter includes a half-bridge circuit 52, a transformer T, an LLC resonance circuit, a circulation current circuit, and a full-wave rectifier circuit. In a moment of switching power switches Q, Q, the circulation current circuit conducts connected rectifiers D, D, respectively, according to voltage drop of the parasitic capacitance in a primary coil N, and forms a circulation current by inducing the current of a resonance inductor Lr. Voltage drop of the parasitic capacitance does not exceed a value obtained by subtracting the voltage drop of a resonance capacitor Cr from an input voltage Vs, or the voltage drop value of the resonance capacitor Cr. Consequently, surplus energy is not transmitted to secondary coils N, N, and since a spike current is not generated on the secondary, the output voltage can be maintained effectively in a constant range (for example, ±5% range of design output voltage) even in the case of light load. |
