| 摘要 |
PURPOSE:To reduce the switching loss of a semiconductor especially in a low speed of an elevator extensively by providing a means to generate a carrier signal by a signal of adding a speed signal proportional to the running speed of a cage and a standard value signal. CONSTITUTION:In an elevator provided with a converter 1 to convert a three- phase AC power source into DC, an inverter 3 to convert a DC smoothed by a smoothing capacitor 2 into a three-phase AC power source, and a three-phase inductive motor 4, a speed generator 20 to output a speed signal 20a according to the rotation frequency of the motor 4 is provided. And the speed signal 20a is input to a carrier signal generating device 30, where the signal 20a and a standard signal 30b are added by an adder 31, the limit value of a limiter 33 is determined by this adding value, and the input value to an integration circuit 34 is converted. As a result, a carrier signal 30a to convert the frequency according to the speed is generated from the integration circuit 34, which is compared with a standard sine wave in a comparator 10, and the inverter 3 is controlled by this output. |
