| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit for driving a surface discharge element that can avoid a circuit from falling into an overload state even when a load capacity increases due to deterioration of the discharge element or variation of an external environment.SOLUTION: In a power supply circuit for driving a surface discharge element in which a discharge electrode and an induction electrode are arranged through a dielectric body interposed therebetween, a switching circuit is configured by connecting two sets of series circuits each comprising positive-side and negative-side switching elements in parallel, and supplied with DC power. A smoothing capacitor is connected to the switching circuit in parallel, and the primary side of a transformer is connected between the output terminals of the switching circuit. Current detection means detects current flowing through the negative-side switching element, and protection operation means detects the resonance frequency of the current from a zero-cross point of the current detected by zero-cross detection means, and performs an overload protection operation based on the variation of the resonance frequency.SELECTED DRAWING: Figure 1 |
