| 摘要 |
PROBLEM TO BE SOLVED: To reduce the harmonic distortion of an input current and keep a high input power factor regardless of the state of a load. SOLUTION: A series circuit of diodes D1 and D2 and a series circuit of capacitors C1 and C2 are connected in parallel to each other and an AC power supply AC is connected between the connection point between the diodes D1 and D2 and the connection point between the capacitors C1 and C2 . An inverter circuit which is also used as an active filter and has switching devices Q1 and Q2 is connected between both ends of the series circuit of the capacitors C1 and C2 . A capacitor C0 is connected between the connection point between an inductor L1 and a discharge lamp DL and the connection point between the diodes D1 and D2 . Therefore, a current which flows from the AC power supply AC so as to store a magnetic energy in the inductor L1 while the inverter circuit functions as the active filter does not flow through the discharge lamp DL, so that the voltage change of the AC power supply AC does not give influence upon a current supplied to the discharge lamp DL. |
