Efficient, high power battery module; D.C. transformers and multi-terminal D.C. power networks utilizing same

• US 4,274,043 A
• Filed: 12/21/1978
• Issued: 06/16/1981
• Est. Priority Date: 12/21/1978
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Heitz, Robert G.
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US05/972,111
• Time in Patent Office: 908 Days
• Field of Search: 320/7, 320/8, 320/14, 320/16, 320/18, 320/15, 320/6, 307/18-20, 307/77, 307/80, 307/82, 307/83, 307/150, 307/151, 363/35, 429/149
• US Class Current: 320/117
• CPC Class Codes: H01M 10/3909 Sodium-sulfur cells
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2200/10 Temperature sensitive devices
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/36 Distribution system, e.g. railroad lighting

Abstract

Multiterminal, high voltage D.C. power networks in which the sub-terminals are electrically isolated from each other comprise D.C. transformers, as the terminals. Each transformer comprises a large number of efficient, high energy batteries, connected as two separate groups: one group made up of paralleled long strings of series connected batteries and the other group made up of paralleled short strings of one or more batteries each. Each transformer also comprises automatic monitoring, control and switching means for periodically exchanging charged and discharged strings between the two groups, one of which--the "primary"--is connected across the supply lines from the power source(s) for the network and the other of which--the "secondary"--is connected across the service lines providing power to users thereof.

Claims

1. A high power battery module adapted for use in D.C. transformers and multiterminal 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 about 95% or more while being continuously cycled for a period of at least 1000 hours, from the open circuit voltate (e_oc) 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, said efficiency being defined as 100 (W_o /W_i), where W_o is the total watt-hours delivered by the unit and W_i is the total watt-hours supplied to it,

(b) an 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 two connect/disconnect switches and a solid state load breaker, one of said switches being connected directly to one of the poles of said battery and the other switch being connected to the other pole through said load breaker,

(e) automatic monitoring means for determining the voltage across said battery and the current therethrough, the latter means being adapted to supply an output, characteristic of the magnitudes of said voltage and current, to a means for developing said control signals, when a latter such control means is connected to said monitoring means,

(f) connecting means by which said switching and monitoring means can be connected to said control means.

3. A module as in claim 1, wherein said cells are alkali metal/chalcogen battery cells.

4. A module as in claim 3, wherein said cells are of the hollow fiber type.

2. A D.C. transformer comprising a plurality of high power battery modules and a control means,

each of said modules 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 about 95% or more while being continuously cycled for a period of at least 1000 hours, from the open circuit voltage (e_oc) 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, said efficiency being defined as 100 (W_o /W_i), where W_o is the total watt hours delivered by the unit and W_i is the toal watt-hours supplied to it,

(b) an 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 two connect/disconnect switches and a solid state load breaker, one of said switches being connected directly to one of the poles of said battery and the other switch being connected to the other pole through said load breaker,

(e) automatic monitoring means for determining the voltage across said battery and the current therethrough, the latter means being adapted to supply an output, characteristic of the magnitudes of said voltage and current, to said control means,

(f) connecting means connecting said monitoring and switching means to said control means,

said modules being so interconnected with each other--through said switching means--and so connected with said control means--through said monitoring and connecting means, as to be operable as a self-regulating, D.C. step-up or step-down transformer having electrically separate primary and secondary circuit sections,

one of said circuit sections comprising 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 same 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 so as to be able, upon receipt of said control signals, to;

(a) disconnect 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_oc 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 connecting 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.

5. A D.C. transformer, according to claim 2, in which said cells are alkali metal/chalcogen battery cells.

6. A D.C. transformer as in claim 5, in which said cells are of the hollow fiber type.

7. A D.C. transformer, according to claim 2, in which each of said long legs additionally comprises from one to several such modules, connected in parallel with one or more of the modules in said leg.

8. A D.C. transformer, according to claim 7, in which the number of said additional modules is such that, when all of the modules in the leg are connected in series, (E_p -NE_oc)÷

NR_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.

9. A D.C. transformer, as in claim 2, constituting a terminal or sub-terminal in a D.C. power distribution system.

11. A D.C. transformer, according to claim 7, constituting a terminal or sub-terminal in a D.C. power distribution system.

14. The transformer of claim 11 in which said cells are hollow fiber type, alkali metal/chalcogen battery cells.

17. The D.C. transformer of claim 11 in which said cells are sodium/sulfur cells of the hollow fiber type.

10. A multiterminal, D.C. power network comprising terminals which are D.C. transformers, each comprising a plurality of high power battery modules and a control means, each of said modules 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 about 95% or more while being continuously cycled for a period of at least 1000 hours, from the open circuit voltage (e_oc 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, said efficiency being defined as 100(W_o /W_i), where W_o is the total watt-hours delivered by the unit and W_i is the total watt-hours supplied to it,

(b) an 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 two connect/disconnect switches and a solid state load breaker, one of said switches being connected directly to one of the poles of said battery and the other switch being connected to the other pole through said load breaker,

(e) automatic monitoring means for determining the voltage across said battery and the current therethrough, the latter means being adapted to supply an output, characteristic of the magnitudes of said voltage and current, to said control means,

(f) connecting means connecting said monitoring and switching means to said control means,

said modules being so interconnected with each other--through said switching means--and so connected with said control means--through said monitoring and connecting means, as to be operable as a self-regulating, D.C. step-up or step-down transformer having electrically separate primary and secondary circuit sections,

one of said circuit sections comprising 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 same 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 so as to be able, upon receipt of said control signals, to;

(a) disconnect 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_oc 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 connecting 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.

12. A multiterminal, D.C. power network wherein all of the terminals are D.C. transformers according to claim 10.

13. A multiterminal, D.C. power network as in claim 12, wherein, in said D.C. transformers, each of said long legs comprises additional such modules connected in parallel with one or more of the modules in said leg, the number of said additional modules being such that, when all of the modules in the leg are connected in series, (E_p -NE_oc)÷

NR_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.

15. The power network of claim 10, in which said cells are alkali metal/chalcogen battery cells of the hollow fiber type.

16. The D.C. network of claim 15, wherein said chalcogen is sulfur.

18. The D.C. network of claim 13, in which the cells are sodium/sulfur cells of the hollow fiber type.