Uninterruptible power supply with isolated bypass winding
First Claim
1. A stabilized power supply system for supplying alternating current power to a critical load, such as a computer, comprising:
- (a) transformer means including an output winding connected with the load, and first and second input windings;
(b) first source means including a battery and an inverter for supplying alternating-current power;
(c) second source means including a bypass voltage source for supplying alternating current power;
(d) transfer switch means having first and second conditions for alternately connecting and disconnecting said first source with said first input winding and for disconnecting and connecting said second source with said second input winding, respectively;
(e) third source means including a utility voltage source for supplying alternating-current power to said transformer means; and
(f) means for varying the angular vector relationship between the voltages of said third (EU) and first (Ei) sources to cause the real component of the inverter current (Ii) at the break-even condition to be a minimum, said vector relationship varying means comprises magnetic shunt means (M) for varying the coupling between the windings of said transformer means;
(g) said transformer means also including a third input winding connected with said utility voltage source, said magnetic shunt means being arranged to at least partially isolate said third winding from said first and second windings.
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Accused Products
Abstract
An uninterruptible power supply including a transformer having a first input winding normally coupling an inverter AC source with a critical AC load, which transformer also includes a second input winding operable to supply power from a bypass source to the load in the event of malfunction of the inverter circuit. The inverter is of the four-quadrant pulse-width-modulated type, thereby to permit recharging of the battery which serves as the DC source to the inverter. An inductance is provided for varying the phase relationship between a utility voltage source and the inverter voltage to produce minimum real inverter current and the "break-even" operating conduction, and a step-up device is provided for increasing the utility voltage to further minimize the break-even inverter current required during normal operation, and to maximize the through-put efficiency.
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Citations
8 Claims
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1. A stabilized power supply system for supplying alternating current power to a critical load, such as a computer, comprising:
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(a) transformer means including an output winding connected with the load, and first and second input windings; (b) first source means including a battery and an inverter for supplying alternating-current power; (c) second source means including a bypass voltage source for supplying alternating current power; (d) transfer switch means having first and second conditions for alternately connecting and disconnecting said first source with said first input winding and for disconnecting and connecting said second source with said second input winding, respectively; (e) third source means including a utility voltage source for supplying alternating-current power to said transformer means; and (f) means for varying the angular vector relationship between the voltages of said third (EU) and first (Ei) sources to cause the real component of the inverter current (Ii) at the break-even condition to be a minimum, said vector relationship varying means comprises magnetic shunt means (M) for varying the coupling between the windings of said transformer means; (g) said transformer means also including a third input winding connected with said utility voltage source, said magnetic shunt means being arranged to at least partially isolate said third winding from said first and second windings. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification