| 摘要 |
PROBLEM TO BE SOLVED: To provide a power unit which has a wide set output range and is less in switching loss. SOLUTION: An inverter 4 for resonance is constituted by connecting a pair of serially connected capacitors 6a and 6b and a pair of serially connected switching elements 8a and 8b in parallel with a DC power source 2. An output transformer 14 composed of a reactor 10 for resonance, a capacitor 12 for resonance, and a primary winding 14P is connected in series with the output of the inverter 4. Output rectifiers 16a and 16b are connected to the secondary winding 14S of the transformer 14 and a direct current is supplied to a load. A current detector 26 which detects the output current flowing to the load, and a switch control signal forming device 32 which compares the detect signal of the detector 26 with a reference signal for setting the output current, amplifies an error, and outputs switch control signals for controlling the switching elements 8a and 8b in accordance with error amplified signals, are provided. When the reference signal for setting the output current drops to a prescribed value, part of the switch control signals is forcibly turned off.
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