| 摘要 |
<p>The purpose of the present invention is to decrease the amount of utility power supplied to a crane, allowing low-voltage transmission. A power-supply device (40) is provided with a chargeable battery (42), for supplying power to an electrical load consisting of a crane, and a PWM converter (41) that receives a predetermined amount of utility power. A charging/discharging control device (53) computes the difference between the amount of power consumed by the electrical load and the amount of utility power supplied, and a charging/discharging device (48) charges or discharges the battery (42) in accordance with said difference.</p> |
