Electricity: power supply or regulation systems – Input level responsive – Phase controlled switching using electronic tube or a three...
Patent
1983-06-09
1985-04-16
Wong, Peter S.
Electricity: power supply or regulation systems
Input level responsive
Phase controlled switching using electronic tube or a three...
323243, 323246, G05F 500
Patent
active
045118361
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a circuit arrangement for maintaining the power drawn by a load from an alternating current source at a value to a high degree independent of the voltage of said source.
Circuit arrangements for said purpose are known, in which a D.C. voltage derived from an A.C. network by rectification is periodically interrupted so as to form square-shaped pulses, the length of which is shortened according as their amplitude increases, the pulse length being controlled by an operational amplifier comparing the fluctuating voltage of the network with a fixed reference voltage.
On account of the complicated and non-linear relationship between the load output and said voltage, it is possible to maintain the output fairly constant merely within a comparatively narrow range of voltages.
The object of the invention is to create a circuit arrangement which, with the use of a small number of components, provides such a compensation of voltage variations of the current source that the power drawn by the load is maintained constant with very small and acceptable deviations, when the voltage of the power source varies between values of the ratio 1:2 or within a still greater range.
The invention is based upon the experience that said power control is easier to realize if the load is fed with pulses formed by those parts of the sine curve of the voltage of the power source that lie next to zero voltage, whereby due consideration can be taken to the fact that when varying the voltage of the power source the energy contents of the pulses vary with the first power of their lengths and with the second power of their amplitudes.
The characterizing features of the invention are set forth in the following claims, and the details of an exemplary embodiment of the circuit are described herein below with reference to the accompanying drawing, in which
FIG. 1 is a circuit diagram and
FIG. 2 shows curve shapes of feeding voltages and output pulses.
The lines AC IN of the circuit are connected to a power source which is assumed to be a distribution network of 110 V and 50 Hz. By means of the diodes D1, D2, D3 and D4 the power supply is rectified, so that between the lines a and c (which may be grounded) there is a potential difference of the curve shape shown in FIG. 2 D, and consisting of consecutive sinusoidal half-waves of the same positive polarity. A zener diode Z1 shunted by a condenser C1 is in series with a resistor R1 connected between the lines a and c and holds the point or line b at a constant, comparative low D.C. voltage (e.g. of the order of 10 V). An operational amplifier OP1 (e.g. of the type RCA 3140) is fed from the line b.
A resistor R3 (e.g. 100 kohm) in series with a resistor R4 (e.g. 47 kohm) is connected between the lines b and c. At the point or line d a voltage of constant value of the order of 3 V is maintained and is supplied to the non-inverting input (+) of the operational amplifier OP1 as a reference voltage.
The inverting input of OP1 is connected to the intermediate point e upon a voltage divider consisting of a series connection of a fixed resistor R3 (330 kohm), a fixed resistor R6 (18 kohm) and an adjustable resistor R7 (50 kohm). In the point e there appears a voltage of the same fully rectified sinusoidal shape (FIG. 2D) as in line a but of a considerably reduced magnitude (about a tenth thereof).
The operational amplifier OP1 is connected via a resistor R8 (47 kohm) to a power transistor TR2 (e.g. of the type Siemens BUZ 45) and triggers the same. The output terminals of said transistor are in series with the resistor R9 (0.1 ohm) and the load R.sub.L connected between the lines a and c. The load is resistive and may consist of a halogen incandescent lamp rated 20 W and 24 v. The transistor TR2 shuts the load R.sub.L on and off momentarily at intervals determined by the operational amplifier.
The circuit so far described operates in the following manner: As long as the voltage of point e supplied to the inverting input of the operational amplifier is less than the constant voltage
REFERENCES:
Patent Abstracts of Japan, Abstract of JP 54-44462, Published 1979-07-04.
Jones Judson H.
Wong Peter S.
LandOfFree
Circuit arrangement for power control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit arrangement for power control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit arrangement for power control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1458748