Battery voltage measurement circuit, battery voltage measurement method, and battery electric control unit

• US 20070285083A1
• Filed: 03/20/2007
• Published: 12/13/2007
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: Keihin Corporation (Hitachi, Ltd.)
• Original Assignee: Keihin Corporation (Hitachi, Ltd.)
• Inventors: Kamata, Seiji
• Granted Patent: US 7,759,903 B2
• Time in Patent Office: Days
• US Class Current: 324/120
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• 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

Abstract

A voltage between both terminals of each unit battery is amplified by a differential amplifier and is then converted by a converter into a predetermined physical quantity that corresponds to the voltage between both terminals of the unit battery. The converted physical quantity is then level-shifted by a detection circuit and is converted into a voltage on a reference potential of the lowest electric potential of the battery assembly. A control unit sequentially selects the converted voltages by a multiplexer, generates serial digital signals by an A/D conversion, and then transmits the serial digital signals to a control operation unit via an isolation buffer circuit. It is, therefore, possible to provide a battery voltage measurement circuit capable of measuring a voltage of each of unit batteries constituting a battery assembly with high accuracy by using a common measurement circuit in a relatively simple and inexpensive configuration.

Claims

1. Battery voltage measurement circuit that measures a voltage between both electrodes of each unit battery in a battery assembly having a plurality of unit batteries which are connected in series, the battery voltage measurement circuit comprising:

a conversion unit that is provided with each unit battery and converts a voltage between both electrodes of the unit battery into a predetermined physical quantity, and

a common measurement unit that processes and measures the physical quantity converted by the conversion unit with respect to each of the unit batteries.

2. The battery voltage measurement circuit according to claim 1,

wherein the measurement unit includes an A/D conversion unit that converts the voltage between both electrodes of the unit battery into a corresponding digital signal.

3. The battery voltage measurement circuit according to claim 1, further comprising:

a level shifting unit that is provided with the conversion unit and converts the physical quantity converted by the conversion unit into a voltage on a reference potential of a lowest electric potential of the battery assembly,

wherein the measurement unit sequentially outputs digital values corresponding to voltages on the reference potential of the lowest electric potential of the battery assembly with respect to each of the unit batteries.

4. The battery voltage measurement circuit according to claim 1,

wherein the conversion unit that corresponds to each of the unit batteries is formed into groups consisting of the predetermined number of the conversion units, which are adjacent to each other;

each group is provided with a charge pump circuit; and

the conversion unit in each group operates with a power supply from the charge pump circuit associated with the each group.

5. The battery voltage measurement circuit according to claim 4, further comprising

a DC/DC converter that is electrically insulated from the battery assembly and is used as an power source for each charge pump circuit.

6. The battery voltage measurement circuit according to claim 1,

wherein the conversion unit includes a voltage/current conversion unit that converts the voltage between both electrodes of the unit battery into a corresponding magnitude of an electric current.

7. The battery voltage measurement circuit according to claim 1,

wherein the conversion unit includes a voltage/frequency conversion unit that converts the voltage between both electrodes of the unit battery into an alternating signal having a corresponding frequency.

8. The battery voltage measurement circuit according to claim 1, further comprising:

a control operation unit that is electrically insulated from the battery assembly; and

a transmitting unit that electrically transmits the digital value corresponding to the voltage between both electrodes of the unit battery from the measurement unit into the control operation unit while keeping insulation between the battery assembly and the control operation unit.

9. A battery voltage measurement method in a battery voltage measurement circuit that measures a voltage between both electrodes of each unit battery in a battery assembly having a plurality of unit batteries which are connected in series,

the battery voltage measurement method comprising the steps by the battery voltage measurement circuit of:

(a) differentially amplifying a voltage between both electrodes of each unit battery;

(b) converting an output voltage obtained in the step (a) into a predetermined physical quantity;

(c) level-shifting the physical quantity converted in the step (b) into a voltage on a reference potential of a lowest electric potential of the battery assembly; and

(d) measuring the voltage, which is level-shifted in the step (c), by a common measurement unit with respect to each of the unit batteries.

10. A battery electric control unit that measures a voltage between both electrodes of each unit battery in a battery assembly having a plurality of unit batteries which are connected in series,

the battery electric control unit comprising a processing unit incorporating:

a differential amplification unit that is provided with each unit battery and detects a voltage between both electrodes of the unit battery through an input unit to output a detected voltage;

a conversion unit that is provided with each differential amplification unit and converts the detected voltage from the differential amplification unit into a predetermined physical quantity;

a level shifting unit that level-shifts the physical quantity converted by the conversion unit into a voltage on a reference potential of a lowest electric potential of the battery assembly; and

a measurement unit that measures the voltage level-shifted by the level shifting unit.

11. The battery electric control unit according to claim 10,

wherein the processing unit is an integrated circuit.