Automatic voltage imbalance detector

• US 4,424,491 A
• Filed: 05/20/1981
• Issued: 01/03/1984
• Est. Priority Date: 05/20/1981
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy
• Original Assignee: United States Department of Energy
• Inventors: Kerwin, William J., McCormick, J. Byron, Bobbett, Ronald E.
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): O'Shea, Kevin D.
• Application Number:
  US06/265,319
• Time in Patent Office: 958 Days
• Field of Search: 324/433, 324/434, 324/430, 324/429, 324/439, 324/140 R, 324/140 D, 429/22, 429/23, 429/61, 320/48, 340/636, 429/90-93
• US Class Current: 324/433
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/34 by heating
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04671 of the individual fuel cell
• CPC Class Codes: H01M 8/04865 Voltage
• CPC Class Codes: H01M 8/249 comprising two or more groupings of fuel cells, e.g. modular assemblies
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

Claims

1. A device for indicating malfunction of at least one voltage cell in a plurality of voltage cells connected in series comprising:

means for adding the voltage magnitudes of two adjacent voltage cells of said plurality of voltage cells connected in series at upper and lower voltage points to obtain a sum voltage;

means for comparing said sum voltage with a central voltage between said two adjacent voltage cells to obtain an error voltage proportional to the difference between said sum voltage and said central voltage; and

switching means for providing an output whenever said error voltage exceeds a predetermined magnitude indicative of a malfunction of at least one of said voltage cells, said switching means having a first transistor connected to conduct whenever said error signal exceeds a predetermined positive voltage and a second transistor connected to conduct whenever said error signal exceeds a predetermined negative voltage.

2. An automatic voltage imbalance detector comprising:

a plurality of voltage cells connected in series such that each two adjacent voltage cells have lower, middle and upper voltage points at connection points in said series;

means for combining the voltage magnitudes at said upper and lower voltage points to obtain a sum voltage;

operational amplifier means for comparing said sum voltage with the voltage magnitude at said middle voltage point to produce an error signal proportional to the difference between said sum voltage and the voltage magnitude at said middle voltage point; and

switching means for producing an output signal whenever said comparison signal exceeds a predetermined error voltage, said switching means having a first transistor connected to conduct whenever said error signal exceeds a predetermined positive voltage and a second transistor connected to conduct whenever said error signal exceeds a predetermined negative voltage.

3. A device for preventing damage to series connected voltage cells due to excessive discharge comprising:

means for detecting voltage levels between said series connected voltage cells during discharge;

means for comparing adjacent voltage levels to produce difference voltage signals;

means for comparing adjacent difference voltage signals to produce an error voltage signal proportional to the difference between said difference voltage signals; and

switching means for producing an output voltage switching signal whenever said error voltage signal exceeds a predetermined absolute magnitude indicative of potential damage to said voltage cells, said switching means having a first transistor connected to produce an output switching signal whenever said error voltage signal exceeds a predetermined positive voltage and a second transistor connected to produce an output switching signal whenever said error voltage signal exceeds a predetermined negative voltage.