| 摘要 |
PROBLEM TO BE SOLVED: To provide a neutral point type inverter from which a constant voltage can be obtained, without changing its circuit constant even when its input voltage is raised. SOLUTION: A neutral point type inverter is constituted, in such a way that commercial power supply is connected to a rectifier DP through a low-pass filter LPF and a serial circuit of a smoothing capacitor Cs and voltage dividing capacitors C1 and C2 and another serial circuit of switching elements Q1 and Q2 which alternately make turning on/off operations are connected in parallel with the output of the rectifier DB. Then diodes D1 and D2 are respectively connected in anti-parallel for the switching elements Q1 and Q2 and a drive circuit DR is connected to the elements Q1 and Q2. In addition, the serial circuit of a capacitor Cx and an inductor Lo is connected between the junctions between the voltage-dividing capacitors C1 and C2 and between the switching elements Q1 and Q2, and a load RL is connected in parallel with an inductor Lo. A constant output voltage is obtained from an inverter, by reducing the boosting effect of the inverter as a boosting inverter through causing the capacitor Cx absorb the voltage the back electromotive force of the inductor Lo. |
