| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power from a solar battery and a battery, and, at the same time, to quickly charge the battery by controlling the number of revolutions per unit time of a motor which is driven with the electric power form the solar battery and/or battery to a prescribed value. SOLUTION: A PWM(pulse width modulation circuit) 16 always detects the number of revolutions per unit time of a motor 15 and, at the same time, controls the number of revolutions of the motor 15 to a prescribed value or its vicinity by chopping the direct current supplied to the motor 15 from a solar battery 12 or a battery 14 in a pulse and controlling the on-duty ratio of the pulse width of the pulse so that the detected number of revolutions (rotating speed) of the motor 15 may become a fixed value (speed). Therefore, the power consumption of the motor 15 is also nearly fixed to a prescribed value. Therefore, when the electric power generated from the solar battery 12 exceeds the nearly fixed power consumption of the motor 15, the excessive electric power is not used for increasing the number of revolutions of the motor 15, and so forth, but for charging the battery 14. Therefore, the charging time of the battery 14 can be shortened. |
