| 摘要 |
PROBLEM TO BE SOLVED: To obtain an inverter control apparatus by which the limit of an inverter can be applied without lowering the running performance of an elevator, which can be made small and lightweight and whose costs can be lowered. SOLUTION: The temperature of a cooling fin is measured by a temperature sensor 18, and whether the temperature exceeds an upper-limit value or not is judged by a temperature judgment means 20. When the temperature is at the upper-limit value or lower, a maximum permissible current with reference to the temperature is computed by a maximum-permissible-current computing means 21, and the maximum permissible current and an inverter output current are compared by a carrier-frequency change means 22. As a result, when the inverter output current exceeds the maximum permissible current, a signal 22a which is used to lower a carrier frequency is output. A carrier-signal generation circuit 15 outputs a carrier signal whose frequency is normally, e.g. 10kHz. When a signal 22a from the carrier-frequency change means 22 is input, the frequency of the carrier signal is changed to 5kHz so that the inverter output current does not exceed the maximum permissible current. |
