| 摘要 |
PURPOSE:To improve the efficiency of a regenerative braking by reducing the regenerative amount upon decreasing of a regenerative load and reducing a slip frequency in the state that the regenerative amount cannot be increased. CONSTITUTION:When a regenerative load decreases during the regenerative brake control of an induction motor 5 so that the voltage 8 of a filter capacitor 3 exceeds a throttle starting voltage 72 for decreasing a motor voltage VM, VM/fINV (fINV: inverter frequency) decreases. At this time when VM/fINV becomes a limiting value 73 or lower capable of suppressing the overvoltage at voltage overvariation time due to the application and the interruption of the load, it reduces the slip frequency fS. Thus, the regenerative brake does not fail by the protection of the overvoltage against the overvariation while the voltage 8 is clamped to an overvoltage protection set value 71. |
