| 摘要 |
An electrical energy source 1, comprising a photovoltaic cell array, 2, 3, or battery 5 and a load 7 are interconnected by switches I1, I2 which are controlled by a circuit 17 in dependence on comparisions amongst the actual battery voltage VB, minimum and maximum desired battery voltages, and the source voltage VP sensed up stream of a diode 19. References Vm1, Vm2 in the region of and respectively lower and higher than a nominal maximum battery voltage, and Vm1, Vm2 in the region of and respectively lower and higher than a nominal minimum battery are used. Switch I1 may be opened when VB>Vm2 or VP<VB, and is closed when VB<Vm1 or VP>(VB+K), where K is chosen to prevent surging of the switch in the case of limited variations in VB and VP. Switch I2 may be opened when VB<Vm1 and closed when VB>Vm2. In a second embodiment, (Fig 5) which may be used to charge a battery during the day and energise a lamp at night, switch I1 is opened when VB>Vm2 and closed when VB<Vm1, and switch I2 is opened when VB<Vm1 and/or VP>(VB+k) and closed when VB>Vm2 and VP<VB. A third embodiment, (Fig 7), is effectively a combination of the first two, switch I1 being controlled in dependence on comparison of VB with VP, Vm1 and Vm2 and switch I2 being controlled in dependence on comparison of VB with VP, Vm1 and Vm2 <IMAGE> |
