AC-AC CONVERTER

摘要

PURPOSE:To obtain such an AC-AC converter that the relative harmonic content in the electric power supplied from the converter does not become larger as compared with the case where all lamps are turned on even when the electric current of a discharge lamp is controlled to a low level by switching load output of the converter by simultaneously switching specific second and first dimmer switches. CONSTITUTION:An LC resonance circuit and harmonic switching element Q1 are connected across a smoothing capacitor C2 and a first dimming switch SW1 which switches the turning-on period of the switching element Q1 is connected to the drive circuit DR of the capacitor C2. Then the connecting point of a harmonic choke TH with a first diode D1 is connected to the element Q1 through a second diode D2 and the series circuit of a load circuit. In addition, the series circuit of a sixth capacitor C6 and second dimmer switch SW2 are connected between the connecting point of a second diode D2 with the load circuit and the negative terminal of a rectifier circuit DB so that the load output of an AC-AC converter can be switched by simultaneously switching the dimmer switches SW2 and SW1.