Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With discharge of cells or batteries
Patent
1981-07-24
1985-03-12
Beha, Jr., William H.
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With discharge of cells or batteries
363 19, 363142, H02J 710
Patent
active
045047758
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
I. Field of the Invention
The invention relates to a circuit arrangement for the controlled supply of a load, as set forth in the classifying portion of claim 1.
II. Description of the Prior Art
For many electrical loads, for example portable devices, which include electric dry razors, electronic flash devices, fluorescent lamps and the like, it is desirable to provide a power supply circuit which can be operated without change-over switching from virtually all d.c. and a.c. mains anywhere in the world, and which supplies power to the load in the required manner, for example at a constant current or a constant voltage or a combination of both. If the load includes a battery or accumulator, so that for example in the case of a dry razor, the device can also be operated independently of the main supply, the power supply circuit should in turn be capable of charging up the battery, independently of the main supply voltage and frequency, or should be capable of feeding power to the load alone, for example when the battery is discharged.
In connection with the above-described situations of use of such a circuit arrangement, a further condition which gives rise to complications is that, because of the restricted amount of space, for example in a dry razor, the space required for accommodating a supply circuit arrangement can only be very small and at the same time the power loss must be kept at a particularly low level because the cooling capabilities are greatly restricted when dealing with a small volume. Finally, there is a requirement in respect of many portable devices for the device to operate satisfactorily, even under high ambient temperature conditions, for example on travelling to tropical countries.
In a known circuit arrangement (U.S. Pat. No. 4,005,351), the input voltage has a strong influence on the mode of operation because the speed of rise of the primary current depends on the input voltage. The period of time for which the first semiconductor switch in the form of a transistor is switched on is then reduced, with the same switch-off current, as the input voltage rises, and the resulting change in frequency leads to a corresponding change in the mean output power. Although, for the purposes of maintaining the output voltage at a constant value, the known circuit arrangement provides for influencing the primary current switch-off value and thus the period of time for which the switch is switched on, by applying a further voltage which is obtained during the non-conducting phase and which is applied to the control electrode of the second semiconductor switch, nonetheless that arrangement does not overcome the basic dependency on the input voltage. As the two control parameters, namely the primary current and the output voltage, are produced at different times, during the conduction and the non-conduction or blocking phases respectively, it is necessary to provide for storage of one value by means of a capacitor. This results in a reduction in the speed of control, and the circuit arrangement cannot therefore adjust immediately to fluctuations in the operating conditions.
A further circuit arrangement is also known [DOS (German laid-open application) No. 27 51 578], for producing a controlled voltage, using a blocking converter or transformer whose primary winding is connected to the input voltage source by way of a transistor which can be switched on by positive feedback, and an emitter resistor. As in the case of the circuit arrangement described hereinbefore, this circuit arrangement also has a severe dependency on the input voltage, which is due to the different speed of rise of the primary current, in dependence on the input voltage. In this case also, control in respect of the output voltage is achieved by producing a voltage during the non-conduction or blocking phase so that a storage capacitor is again required.
A feedback-controlled single-cycle blocking converter is also known [DOS (German laid-open application) No. 25 43 371], in which the associated transf
REFERENCES:
patent: 3435320 (1969-03-01), Lee et al.
patent: 4220905 (1980-09-01), Quarton
Zuider, "Fast-Charging Systems for Ni-Cd Batteries," EDN, vol. 15, No. 2, pp. 65-67, Jan. 15, 1970.
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