| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a portal type crane device self-propelling in a container yard, improved in power supply efficiency when a power is supplied to the crane device from a transformer via a bus bar. <P>SOLUTION: The crane device 10 includes a PWM converter 40, and inverters 41 and 42. The PWM converter switches an AC power fed from the bus bar 8 by a PWM control to convert the AC power to a DC power so that a phase difference between the voltage and current of the AC power is reduced. The inverters convert the obtained DC power into an AC power for driving and supply the AC power to motors 30, 31, and 32 of the crane device. <P>COPYRIGHT: (C)2013,JPO&INPIT |
