| 摘要 |
PROBLEM TO BE SOLVED: To suppress overvoltage to a switching element, reduce the loss related to charging/discharging of a snubber circuit and the switching loss of the switching element, and obtain a stable power converter wherein noises due to fluctuation in voltage is reduced. SOLUTION: IGBTs Q1, Q2 constituting an inverter for one phase are connected in parallel with a series circuit of diodes Ds1, Ds3 and capacitors C1, C3. The diodes Ds1, Ds3 are connected in parallel with a circuit means composed of capacitors C2, C4, diodes Ds2, Ds4 and resistors R1, R2. A snubber capacitor C5 for clamping is also included. The series circuit of the capacitors C1, C2 and the series circuit of the capacitors C3, C4 act as a snubber capacitor with variable capacitance since the diodes Ds1, Ds3 are reverse-biased by the voltage of the capacitors C2, C4. When the IGBTs Q1, Q2 interrupt current, therefore, it is possible to reduce the voltage applied to the IGBTs Q1, Q2 and the loss that is otherwise produced when a capacitor in a snubber circuit is discharged. |
