D.C. transformers and multi-terminal D.C. power network utilizing the same

Claim 2

A high power battery module adapted for use in D.C. transformers and multi-terminal D.C. power distribution systems based on such transformers, said module comprising: (a) a battery of series-connected, rechargeable cell units, said battery having an open circuit voltage (E oc ) of at least 400 volts and each of said cell units consisting of a single cell or a plurality of cells in parallel and being capable of maintaining an electrical efficiency of greater than 95% while being continuously cycled for a period of at least 1000 hours, from the open circuit voltage (e ) it has when fully charged to a lesser (e oc ) and back, at an average rate of at least 80 watts per pound of electrochemically reactive materials in the cell unit, (b) individual means associated with each of said cell units and adapted to respond automatically to development of an excessive load voltage across said cell unit by establishing a by-pass connection across it so that the series circuit through the battery is maintained, (c) individual fuse means connected one to one in series with each of said cells, (d) switching means operable by control signals to make or break a discharge circuit through said battery and to break or make a charging circuit through said battery, said switching means comprising a connect/- disconnect switch connected through an intervening load breaker to one of the poles of said battery and another connect/- disconnect switch connected to the other pole, (e) automatic monitoring means for determining the voltage across said battery and the current therethrough, (f) means for transmitting said voltage and current information to a control means, and (g) means for transmitting control signals from said control means to said switching means.

Claim 3

The module of Claim 1, wherein said cells are alkali metal/chalcogen battery cells having an efficiency defined as 100(W /W.), where W is the total watt-hours delivered by the unit and W i is the total watt-hours supplied to it.

Claim 4

The module of Claim 2, wherein the cells are sodium/sulfur cells of the hollow fiber type.

Claim 5

A self-regulating, D.C. step-up or step-down transformer having electrically separate primary and secondary circuit sections, said transformer comprising a plurality of the battery modules of Claims 1, 2 or 3, interconnected with each other, wherein one of said circuit sections comprises a plurality of short legs connected in parallel and the other comprising a plurality of long legs connected in parallel, each short leg comprising one of said modules or a plurality of said modules in series connection, the total number of the latter modules therein being x, and each long leg comprising a series string of N of said modules, the number of legs in each of said primary and secondary sections being at least equal to the ratio of the total current through the section to the maximum permissible current through the individual component cell units in said modules, said switching means being adapted upon receipt of said control signals, to: (a) disconnent one or more discharged secondary legs at a time and to subsequently connect the modules of which the latter legs consist to form at least one new leg for the primary and connect said new legs in the primary, (b) disconnect one or more old primary legs at a time and to subsequently connect the modules of which the latter legs consist to form at least one new secondary leg and connect said new secondary legs in the secondary, said control means being adapted to (1) determine, from the information provided by said monitoring means, what the open circuit voltage and internal resistance of each battery in the transformer is, (2) in accordance with said pre-established criteria, including the permissible internal volt-amperes losses, the relationship between e and ampere-hours capacity during charge and discharge of the cells of which the batteries are composed and the magnitude of the discharge current through the secondary, to determine when each of said legs should be taken off or put on discharge or charge, (3) to develop said control signals and to provide same, through said transmitting means and at appropriate intervals, to said switching means, so that the batteries comprised in said short and long legs are repeatedly and alternately charged and discharged between preselected, higher and lower, open circuit voltages.

Claim 6

The transformer of Claim 4, wherein each of said long legs additionally comprises from one to several modules, connected in parallel with . one or more of the modules in said leg.

Claim 7

The transformer of Claim 4 or 5, wherein the number of said additional modules is such that, when all the modules in the leg are connected in series, (E p - N E oc )÷N R B at a preselected, minimum fractional value of L, will have essentially the same value as when L = 1 and each of the additional modules is connected in parallel with another of said modules, and N is the total number of said modules connected in series, R B is the average resistance of the batteries in said N modules, E oc is the average open circuit voltage of the batteries in said N modules and L is the load and is 1 at full load.

Claim 8

The transformer of Claim 4, 5 or 6 constituting a terminal or sub-terminal in a D.C. power distribution system.

Claim 9

A plurality of D.C. transformers, according to Claim 4, 5 or 6, constituting terminals in a multiterminal, D.C. power network.

Claim 10

A multiterminal D.C. power network according to Claim 8, wherein all of the terminals are D.C. transformers according to Claim 4, 5 or 6.