| 摘要 |
PROBLEM TO BE SOLVED: To reduce switching loss by making constant the number of carriers per period when inverter frequency satisfies conditions higher than a specified value and below a maximum current limit value, thereby lowering the carrier frequency. SOLUTION: A three-phase inverter 7 is constituted by connecting three arms 6-1, 6-2, 6-3, each comprising switching elements 4, 5 connected in series, in parallel with a battery 1. The switching elements 4, 5 are operated by a gate drive circuit 13 and a control circuit 14 comprising a microcomputer performs processing including current limitation and generation of operational signal for the inverter 7 by judging detection signal received from current sensors 9, 10 and a rotation sensor 11. Carrier frequency is decreased by performing control for making constant the number of carriers per period of the inverter frequency when the r.p.m. of an AC motor 8 exceeds a specified value below a maximum current limit value. |
