DC power supply circuit
First Claim
1. A dc power supply circuit for supplying simultaneously dc voltages to a dc load and to a storage device, said dc load and storage device being operative to draw varying amounts of current within corresponding ranges of current and having a predetermined maximum permissible value of current which may be drawn jointly thereby at any given instant, said dc power supply circuit comprising:
- dc source means operative to provide a dc voltage;
first circuit means coupled to the dc source means and to the dc load, said first circuit means being operative in response to a dc voltage provided by the dc source means to supply a dc voltage of a predetermined fixed value to the dc load for enabling the dc load to draw current and, as the current drawn by the dc load varies within its associated range of values, to maintain the dc voltage supplied to the dc load at the predetermined fixed value;
second circuit means coupled to the dc source means and to the storage device and operative in response to the aforesaid dc voltage provided by the dc source means to supply a dc voltage to the storage device for enabling the storage device to draw current;
current sensing means in circuit with the first and second circuit means and the dc load and storage device and operative to sense the current drawn jointly by the dc load and the storage device and to produce a signal indicative thereof; and
control circuit means coupled to the current sensing means and to the second circuit means, said control circuit means being operative in response to the signal produced by the current sensing means as current is sensed by the current sensing means to cause the second circuit means to supply a dc voltage to the storage device, said dc voltage having a value at any given instant for enabling the storage device to draw current of a value equal to the difference between the then existing value of current drawn by the dc load and the predetermined maximum permissible value of current which may be drawn jointly by the dc load and the storage device, whereby as the value of current drawn by the dc load and the storage device varies and is sensed by the current sensing means the value of the dc voltage supplied by the second circuit means to the storage device and the current drawn by the storage device also vary in accordance with the variation in current sensed by the current sensing means.
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Accused Products
Abstract
A dc power supply circuit for supplying simultaneously dc voltages to a dc load and to a standby battery employed to power the load upon a loss of dc power to the load. The load is adapted to draw varying amounts of current.
The dc power supply circuit in accordance with the invention includes a capacitor which is arranged to retain a dc voltage derived from an ac voltage. A fixed voltage regulator circuit coupled to the capacitor operates to supply a fixed dc voltage to the load and to maintain this voltage as the current drawn by the load varies. An adjustable voltage regulator circuit coupled to the capacitor operates to supply a varying dc voltage to the battery as the current drawn by the load varies. The varying voltage of the adjustable voltage regulator circuit is achieved by a current sensing resistor which senses the current drawn jointly by the load and the battery and which causes control circuitry coupled to the adjustable voltage regulator circuit to vary the dc voltage thereof in accordance with variations in the current sensed by the current sensing resistor. In accordance with the invention, the current drawn jointly by the load and battery is limited to a predetermined maximum amount, for example, one ampere, with the load being supplied first and at all times with its needed current and the difference between the current drawn by the load at any given instant and one ampere being made available to the battery.
19 Citations
10 Claims
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1. A dc power supply circuit for supplying simultaneously dc voltages to a dc load and to a storage device, said dc load and storage device being operative to draw varying amounts of current within corresponding ranges of current and having a predetermined maximum permissible value of current which may be drawn jointly thereby at any given instant, said dc power supply circuit comprising:
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dc source means operative to provide a dc voltage; first circuit means coupled to the dc source means and to the dc load, said first circuit means being operative in response to a dc voltage provided by the dc source means to supply a dc voltage of a predetermined fixed value to the dc load for enabling the dc load to draw current and, as the current drawn by the dc load varies within its associated range of values, to maintain the dc voltage supplied to the dc load at the predetermined fixed value; second circuit means coupled to the dc source means and to the storage device and operative in response to the aforesaid dc voltage provided by the dc source means to supply a dc voltage to the storage device for enabling the storage device to draw current; current sensing means in circuit with the first and second circuit means and the dc load and storage device and operative to sense the current drawn jointly by the dc load and the storage device and to produce a signal indicative thereof; and control circuit means coupled to the current sensing means and to the second circuit means, said control circuit means being operative in response to the signal produced by the current sensing means as current is sensed by the current sensing means to cause the second circuit means to supply a dc voltage to the storage device, said dc voltage having a value at any given instant for enabling the storage device to draw current of a value equal to the difference between the then existing value of current drawn by the dc load and the predetermined maximum permissible value of current which may be drawn jointly by the dc load and the storage device, whereby as the value of current drawn by the dc load and the storage device varies and is sensed by the current sensing means the value of the dc voltage supplied by the second circuit means to the storage device and the current drawn by the storage device also vary in accordance with the variation in current sensed by the current sensing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification