| 摘要 |
<p>An induction motor 6 of an elevator is energised by a variable-voltage, variable-frequency inverter 5 supplied by a battery 4, and the charging rate of the battery 4 from source 1 is controlled in dependence on the rate of discharge of the battery to the inverter 5. A control circuit 14 includes relays for sensing balanced, heavy and light loading of the elevator cage 9, ascent, descent, acceleration, deceleration and constant speed operation. When the motor 6 is drawing heavy current during acceleration or constant speed operation, a command circuit 15 responsive to the relays causes the battery to be charged via a charging circuit 11 at a rate which is greater during such acceleration than during such constant speed operation. At other times, such as constant speed and deceleration stages of a heavy load descent, the battery is regeneratively charged via the inverter 5, the command circuit 15 then causing the battery to be discharged by a circuit 12 at a rate which is higher during the deceleration than during the constant speed operation. The system thus tends to maintain the battery at a constant charge state. Circuit 14 is also responsive to a feedback signal from a current detector 13. In an alternative embodiment, (Figure 7), there is no discharging circuit 12 and the value of a resistor in series with the charging path of the battery 4 from supply 1 is switched in dependence on the battery discharge rate. <IMAGE></p> |
