INTRINSICALLY POWERED ELECTRONIC MONITOR FOR FUEL CELLS

• US 3,808,534 A
• Filed: 11/15/1972
• Issued: 04/30/1974
• Est. Priority Date: 11/15/1972
• Status: Expired due to Term

• Current Assignee: Francis G. Charest, Warren S. Summers
• Original Assignee: Francis G. Charest, Warren S. Summers
• Inventors: Summers, Warren S., Charest, Francis G.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US05/306,647
• Time in Patent Office: 531 Days
• Field of Search: 340/249,248A 320/39,48 328/148
• US Class Current: 340/517
• CPC Class Codes: G01R 31/378 specially adapted for the type of battery or accumulator
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 3/36 involving comparison of the voltage or current values at corresponding points of different systems, e.g. of parallel feeder systems

Abstract

A fuel cell monitor compares the voltages produced by each of a series of fuel cell stacks in order to monitor their outputs. If a malfunction occurs in any cell within a stack such as a short circuit or a cell becoming negative, the output voltage from that stack is reduced, and the monitor gives a warning or shuts down the entire series of fuel cells. The monitor is powered by the cell stacks or by an inverter which is connected to the fuel cells. In one embodiment the monitor indicates which of the fuel cell stacks is malfunctioning and maintains the indication until manually reset. Any number of stacks may be monitored by the fuel cell monitor described herein.

Claims

1. A monitor for a plurality of fuel cell stacks, each said fuel cell stack comprising a plurality of series connected fuel cells, each said fuel cell stack being connected electrically in series with the other said fuel cell stacks, each of said fuel cell stacks generating an output voltage which is substantially equal to the output voltage produced by the other said fuel cell stacks during normal operation, comprising a summing amplifier having first and second input terminals and an output terminal, means connecting to said first input terminal the negative terminal of one of said fuel cell stacks and having a voltage Va and the positive terminal of a second fuel cell stack immediately adjacent to said one fuel cell stack and having a voltage Vc, means connecting to said second input terminal the voltage Vb produced at the junction of the positive terminal of said one fuel cell stack and the negative terminal of said second fuel cell stack, said summing amplifier producing at its output terminal a voltage proportional to Vc-2Vb+Va, comparator means for comparing the voltage at the output terminal of said summing amplifier with a reference voltage, and signal means actuated only when the voltage at the output terminal at said summing amplifier exceeds said reference voltage for signifying the occurrence of a malfunction in one of said fuel cell stacks.

2. A monitor as in claim 1 in which said comparator means includes a first comparator circuit having a pair of input terminals and an output terminal, a first source of reference voltage, means connecting said first reference voltage source to one of said first comparator circuit input terminals, means including a first series diode connecting the output terminal of said summing amplifier with the other said input terminal of said first comparator circuit, a second comparator circuit having a pair of input terminals and an output terminal, a second source of reference voltage, means connecting said second reference voltage source to one of said second comparator circuit input terminals, means including a second series diode reversed in direction from said first series diode connecting the output terminal of said summing amplifier with the other said input terminal of said second comparator circuit, and means connecting the output terminals of first and second comparator circuits with said signal means.

3. A monitor as in claim 2 and including a series diode connected between the output terminal of each of said first and second comparator circuits and said signal means for passing a signal to actuate said signal means only when the voltage at the output terminal of said summing amplifier exceeds the reference voltage applied to one of said comparator circuits.

4. A monitor as in claim 1 and including time delay means connected between said comparator means and said signal means.

5. A monitor for a plurality of fuel cell stacks connected electrically in series, each said stack generating a substantially equal output voltage during normal operation, comprising a summing amplifier circuit having a pair of input terminals, means feeding the voltages generated by first and second series connected fuel cell stacks to said summing amplifier circuit input terminals, the voltage at the common connection between said first and second fuel cell stacks being fed to one of said input terminals and the voltage at the noncommon side of both said fuel cell stacks being fed to the other said input terminal, the output produced by said summing amplifier circuit being a voltage proportional to the difference in the voltages generated by said first and second fuel cell stacks, means comparing said difference voltage with a reference voltage to produce an output signal when said difference voltage exceeds said reference voltage, and means responsive to said output signal for indicating the occurrence of a malfunction in one of said fuel cell stacks.