Unidirectional power transfer method and apparatus

Claim 2

In an alternating current power distribution system of the type including supply voltage feeders, a load network and unidirectional power transfer means for permitting power to be transferred from said supply voltage feeders to said load network and for preventing power being transferred from said load network toward said feeders; the improvement wherein said unidirectional power transfer means comprises: a. transformer means electrically connected between said supply voltage feeders and said load network and adapted to be switched between a first and second state, the transformer means when in said first state coupling by induction said supply voltage feeders and said load network, the transformer means when in said second state essentially electrically isolating said supply voltage feeders from said load network; and b. control means coupled to said transformer means for switching said transformer means to said first state when the supply voltage from said supply voltage feeders is not less than, nor lagging, the load voltage of said load network, and switching said transformer means to said second state when the difference between the phase of the load voltage and the phase of the load current of said load network exceeds a predetermined amount.

Claim 3

The improvement as defined by claim 1 wherein said predetermined amount is approximately 90.degree..

Claim 4

The improvement as defined by claim 1 wherein said control means comprises: a. first means for sensing the magnitude and phase of said supply voltage and said load voltage and generating a closing command signal for effecting said switching of said transformer means to said first state when the supply voltage is not less than, nor lagging, the load voltage; and b. second means coupled to said load network for generating an opening command signal for effecting said switching of said transformer means to said second state in anticipation of the difference between the phase of the load voltage and the phase of the load current exceeding 90.degree..

Claim 5

The improvement as defined by claim 3 wherein said transformer means includes primary and secondary windings and control winding means for inductively coupling said primary winding with said secondary winding when current through said control winding means is above a predetermined minimum value and for preventing such coupling when the current through such control winding means is below said predetermined minimum value.

Claim 6

The improvement as defined by claim 4 wherein said control means further comprises coupling control means coupled to said control winding means for regulating the extent of current through said control winding means.

Claim 7

The improvement as defined by claim 5 wherein said coupling control means is a saturable reactor.

Claim 8

The improvement as defined by claim 6 wherein said coupling control means increases the current above said predetermined minimum value through said control winding means upon the generation of said closing command signal from said first means and reduces the current through said control winding means below said predetermined minimum value upon the generation of said opening command signal from said second means.

Claim 9

The improvement as defined by claim 7 wherein said first means comprises a magnitude comparator for generating a first output signal when the supply voltage is equal to, or greater than, the load voltage; a phase comparator for generating a second output signal when the phase of the supply voltage is equal to, or leading, the phase of the load voltage; and signal generating means for generating said closing command signal upon the simultaneous occurrence of said first and second output signals.

Claim 10

The improvement as defined by claim 7 wherein said second means comprises sensing means for generating a pair of output signals respectively representative of phase of the load voltage and load current and phase comparator means coupled to said sensing means for generating the said opening command signal when said pair of output signals indicate a phase relationship therebetween approaching, but less than 90.degree..

Claim 11

Apparatus for assuring the unidirectional transfer of alternating current power between input and output terminals having respective voltages thereacross, a load being disposed at said output terminals, said apparatus comprising: a. magnetic switching means, when closed, for inductively coupling said power between said input and output terminals and, when opened, for preventing said coupling; b. first means coupled to said input and output terminals for generating a closing command signal for closing said magnetic switching means when the voltage across said input terminals is not less than, nor lagging, the voltage across said output terminals; and c. second means coupled to said output terminals for generating an opening command signal for opening said magnetic switching means in response to the difference between the phase of the voltage and the phase of the current of the load at said output terminals approaching 90.degree..

Claim 12

Apparatus for assuring the unidirectional transfer of alternating current power between input and output terminals having respective voltages thereacross, a load being disposed at said output terminals, said apparatus comprising: a. magnetic switching means, when closed, for inductively coupling said power between said input and output terminals and, when opened, for preventing said coupling; b. first means coupled to said input and output terminals for generating a closing command signal for closing said magnetic switching means when the voltage across said input terminals is not less than, nor lagging, the voltage across said output terminals; and c. second means coupled to said output terminals for generating an opening command signal for opening said magnetic switching means in response to the difference between the phase of the voltage and the phase of the current of the load at said output terminals approaching 90.degree..

Claim 13

The apparatus as defined by claim 10 wherein said magnetic switching means comprises transformer means having primary and secondary windings respectively coupled to the input and output terminals and control winding means for inductively coupling said primary winding with said secondary winding when current through said control winding means is above a predetermined minimum value and for preventing such coupling when the current through such control winding means is below said predetermined minimum value.

Claim 14

The apparatus as defined by claim 11 further including third means having inputs respectively coupled to said first and second means and an output coupled to said control winding means for regulating the extent of current through said control winding means.

Claim 15

The apparatus as defined by claim 12 wherein said third means includes a saturable reactor.

Claim 16

The apparatus as defined by claim 12 wherein said third means increases the current above said predetermined minimum value through said control winding means upon the generation of said closing command signal from said first means and reduces the current through said control winding means below said predetermined minimum value upon the generation of said opening command signal from said second means.

Claim 17

The apparatus as defined by claim 14 wherein said third means includes a saturable reactor.

Claim 18

The apparatus as defined by claim 10 wherein said first means comprises a magnitude comparator for generating a first output signal when the voltage across said input terminals is equal to, or greater than, the voltage at said output terminals; a phase comparator for generating a second output signal when the phase of the voltage at said input terminals is equal to, or leading, the phase of the voltage at said output terminals; and signal generating means for generating said closing command signal upon the simultaneous occurrence of said first and second output signals.

Claim 19

The apparatus as defined by claim 10 wherein said second means comprises sensing means for generating a pair of output signals respectively representative of phase of the voltage and current at said output terminals and phase comparator means coupled to said sensing means for generating the said opening command signal when said pair of output signals indicate a phase relationship therebetween approaching 90.degree..

Claim 20

The apparatus as defined by claim 14 wherein said first means comprises a magnitude comparator for generating a first output signal when the voltage across said input terminals is equal to, or greater than, the voltage at said output terminals; a phase comparator for generating a second output signal when the phase of the voltage at said input terminals is equal to, or leading, the phase of the voltage at said output terminals; and signal generating means for generating said closing command signal upon the simultaneous occurrence of said first and second output signals.

Claim 21

The apparatus as defined by claim 14 wherein said second means comprises sensing means for generating a pair of output signals respectively representative of phase of the voltage and current at said output terminals and phase comparator means coupled to said sensing means for generating the said opening command signal when said pair of output signals indicate a phase relationship therebetween approaching 90.degree..

Claim 24

Magnetic switching apparatus for assuring the unidirectional transfer of alternating current power between input and output terminals, a load network being disposed at said output terminals, said apparatus comprising: a. transformer means having primary and secondary windings respectively connected with said input and output terminals and a control winding means for inductively coupling said primary winding with said secondary winding when current through said control winding means is above a predetermined minimum value and for preventing such coupling when the current through such control winding means is below said predetermined minimum value; b. first means for comparing the magnitude and phase of the voltage across said input terminals with the magnitude and phase of the voltage across said output terminals and generating a first command signal for increasing the current through said control winding means above said predetermined minimum value when said so-compared magnitude and phase indicates that said alternating current power will flow from said input terminals toward said output terminals, thereby to couple said input and output terminals; and c. second means for comparing the phase of the current through said load network with the phase of the voltage across said output terminals and generating a second command signal for reducing the current through said control winding below said predetermined minimum value when the phase relationship between the load current and the voltage across said output terminals indicates that said alternating current power will flow from said output terminals toward said input terminals, thereby to effectively electrically isolate said input terminals from said output terminals to prevent such power flow from said output terminals toward said input terminals.

Claim 25

Magnetic switching apparatus for assuring the unidirectional transfer of alternating current power between input and output terminals, a load network being disposed at said output terminals, said apparatus comprising: a. transformer means having primary and secondary windings respectively connected with said input and output terminals and a control winding means for inductively coupling said primary winding with said secondary winding when current through said control winding means is above a predetermined minimum value and for preventing such coupling when the current through such control winding means is below said predetermined minimum value; b. first means for comparing the magnitude and phase of the voltage across said input terminals with the magnitude and phase of the voltage across said output terminals and generating a first command signal for increasing the current through said control winding means above said predetermined minimum value when said so-compared magnitude and phase indicates that said alternating current power will flow from said input terminals toward said output terminals, thereby to couple said input and output terminals; and c. second means for comparing the phase of the current through said load network with the phase of the voltage across said output terminals and generating a second command signal for reducing the current through said control winding below said predetermined minimum value when the phase relationship between the load current and the voltage across said output terminals indicates that said alternating current power will flow from said output terminals toward said input terminals, thereby to effectively electrically isolate said input terminals from said output terminals to prevent such power flow from said output terminals toward said input terminals.

Claim 26

The apparatus as defined by claim 1 wherein said first command signal is generated when the voltage across said input terminals is not less than, and leading, the voltage across said output terminals; and wherein said second command signal is generated when the difference between the phase of the voltage across said output terminals and the phase of said load current is approximately 90.degree..