Battery voltage monitoring device using capacitor circuit and switch failure detection circuit

• US 10,139,453 B2
• Filed: 01/16/2014
• Issued: 11/27/2018
• Est. Priority Date: 01/16/2013
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Mizoguchi, Tomomichi
• Primary Examiner(s): Grant, Robert
• Assistant Examiner(s): Trischler, John
• Application Number:
  US14/156,930
• Publication Number:
  US 20140197841A1
• Time in Patent Office: 1,776 Days
• Field of Search: 324425, 324434, 324426, 324429, 324433
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B60L 58/18 of two or more battery modules
• 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: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

In a voltage monitoring apparatus, a capacitor circuit includes at least one capacitor. Input-side switches are connected to electrode terminals of at least one battery cell, and apply voltage to terminals of the capacitor. A voltage detection circuit includes a pair of voltage sensing terminals connected to terminals of the capacitor, and detects the potential difference across voltage sensing terminals. Output-side switches are connected to terminals of the capacitor, and apply voltage across terminals of the capacitor to the voltage sensing terminals. An impedance circuit is connected to the voltage sensing terminals. A stabilizing power circuit is connected to the voltage sensing terminals via the impedance circuit, and stabilizes voltage of the voltage sensing terminals. Based on the detected voltage when one of the output-side switches is turned on, an on-failure of the remaining output-side switches which should not be turned on are detected by a control unit.

Claims

1. A voltage monitoring apparatus comprising:

a capacitor circuit including at least one capacitor;

an input-side switch group that includes a plurality of input-side switches connected to at least one pair of electrode terminals of at least one battery cell, the input-side switch group applying voltage to a pair of terminals of the at least one capacitor;

a voltage detection circuit that includes at least one pair of voltage sensing terminals connected to each of the terminals of the at least one capacitor, the voltage detection circuit detecting a potential difference across the at least one pair of voltage sensing terminals;

an output-side switch group that includes a plurality of output-side switches connected to the terminals of the at least one capacitor, the output-side switch group applying voltage across the terminals of the at least one capacitor to the at least one pair of voltage sensing terminals;

switch control means for controlling each of the plurality of input-side switches and each of the plurality of output-side switches;

failure detecting means for detecting, on the basis of the voltage detected by the voltage detection circuit when one of the output-side switches is turned on, an on-failure of at least one of the remaining output-side switches which should not be turned on;

an impedance circuit that is connected to each of the at least one pair of voltage sensing terminals, the impedance circuit being connected to each of the plurality of output-side switches, connected to the terminals of the at least one capacitor, via the each of the at least one pair of voltage sensing terminals; and

a stabilizing power circuit that is connected to each of the at least one pair of voltage sensing terminals via the impedance circuit and stabilizes voltage of each of the at least one pair of voltage sensing terminals, wherein

the impedance circuit is configured such that a time constant of a circuit configured by the impedance circuit and the at least one capacitor, which are connected to each other via each of the plurality of output-side switches and the each of the at least one pair of voltage sensing terminals, becomes longer than a required detection time that is taken from when a voltage across the terminals of the at least one capacitor is applied to the at least one pair of voltage sensing terminals until when a potential difference between the at least one pair of voltage sensing terminals is detected by the voltage detection circuit,

the voltage detection circuit includes a differential amplifier circuit that amplifies and outputs at least one potential difference between the at least one pair of voltage sensing terminals;

the differential amplifier circuit includes at least one pair of input resistors connected to the at least one pair of voltage sensing terminals; and

the stabilizing power circuit is connected to each of the at least one pair of voltage sensing terminals via the at least one pair of input resistors.

2. The voltage monitoring apparatus according to claim 1, wherein:

the stabilizing power circuit is connected to the at least one pair of voltage sensing terminals and is connected to one input terminal of the differential amplifier circuit such that a predetermined offset voltage is added to an output signal of the differential amplifier circuit.

3. The voltage monitoring apparatus according to claim 1, wherein

the at least one battery cell is a plurality of battery cells configuring a battery pack which is installed in a vehicle.

4. The voltage monitoring apparatus according to claim 1, wherein

the stabilizing power circuit includes a power source, resistors, and a buffer circuit, and generates a constant voltage by dividing a voltage of the power source by using the resistors and output the generated constant voltage via the buffer circuit.

5. The voltage monitoring apparatus according to claim 1, wherein

the at least one pair of input resistors is connected to the at least one pair of voltage sensing terminals on a first side of the at least one pair of input resistors and connected to input terminals of a differential amplifier of the differential amplifier circuit on a second side of the at least one pair of input resistors;

and

the stabilizing power circuit is connected to each of the at least one pair of voltage sensing terminals via the impedance circuit on a first side of the at least one pair of input resistors.

6. The battery system according to claim 5, further comprising an offset power circuit configured to generate an offset voltage and having an output terminal connected to the second side of one of the input resistors of the differential amplifier circuit and to one of the input terminals of the differential amplifier of the differential amplifier circuit.

7. A battery system comprising:

a battery pack that is configured by at least one battery cell; and

a voltage monitoring apparatus that includes;

a capacitor circuit including at least one capacitor;

an input-side switch group that includes a plurality of input-side switches connected to at least one pair of electrode terminals of the at least one battery cell, the input-side switch group applying voltage to a pair of terminals of the at least one capacitor;

a voltage detection circuit that includes at least one pair of voltage sensing terminals connected to each of the terminals of the at least one capacitor, the voltage detection circuit detecting a potential difference across the at least one pair of voltage sensing terminals;

an output-side switch group that includes a plurality of output-side switches connected to the terminals of the at least one capacitor, the output-side switch group applying voltage across the terminals of the at least one capacitor to the at least one pair of voltage sensing terminals;

switch control means for controlling each of the plurality of input-side switches and each of the plurality of output-side switches;

failure detecting means for detecting, on the basis of the voltage detected by the voltage detection circuit when one of the output-side switches is turned on, an on-failure of at least one of the remaining output-side switches which should not be turned on;

an impedance circuit that is connected to each of the at least one pair of voltage sensing terminals, the impedance circuit being connected to each of the plurality of output-side switches, connected to the terminals of the at least one capacitor, via the each of the at least one pair of voltage sensing terminals; and

a stabilizing power circuit that is connected to each of the at least one pair of voltage sensing terminals via the impedance circuit and stabilizes voltage of each of the at least one pair of voltage sensing terminals, wherein

the impedance circuit is configured such that a time constant of a circuit configured by the impedance circuit and the at least one capacitor, which are connected to each other via each of the plurality of output-side switches and the each of the at least one pair of voltage sensing terminals, becomes longer than a required detection time that is taken from when a voltage across the terminals of the at least one capacitor is applied to the at least one pair of voltage sensing terminals until when a potential difference between the at least one pair of voltage sensing terminals is detected by the voltage detection circuit,

the voltage detection circuit includes a differential amplifier circuit that amplifies and outputs at least one potential difference between the at least one pair of voltage sensing terminals;

the differential amplifier circuit includes at least one pair of input resistors connected to the at least one pair of voltage sensing terminals; and

the stabilizing power circuit is connected to each of the at least one pair of voltage sensing terminals via the at least one pair of input resistors.

8. The battery system according to claim 7, wherein

the stabilizing power circuit includes a power source, resistors, and a buffer circuit, and generates a constant voltage by dividing a voltage of the power source by using the resistors and output the generated constant voltage via the buffer circuit.

9. The voltage monitoring apparatus according to claim 7, wherein

the at least one pair of input resistors is connected to the at least one pair of voltage sensing terminals on a first side of the at least one pair of input resistors and connected to input terminals of a differential amplifier of the differential amplifier circuit on a second side of the at least one pair of input resistors;

and

the stabilizing power circuit is connected to each of the at least one pair of voltage sensing terminals via the impedance circuit on a first side of the at least one pair of input resistors.

10. The battery system according to claim 9, further comprising an offset power circuit configured to generate an offset voltage and having an output terminal connected to the second side of one of the input resistors of the differential amplifier circuit and to one of the input terminals of the differential amplifier of the differential amplifier circuit.