VOLTAGE MEASURING APPARATUS AND BATTERY MANAGEMENT SYSTEM INCLUDING THE SAME

• US 20140239966A1
• Filed: 02/25/2014
• Published: 08/28/2014
• Est. Priority Date: 02/25/2013
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Korea Semiconductor Limited (ON Semiconductor Corporation)
• Inventors: SONG, Moonsik, HEO, Seok
• Granted Patent: US 9,645,201 B2
• Time in Patent Office: Days
• US Class Current: 324/434
• 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: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The voltage measuring apparatus is connected to a plurality of battery cells connected to each other in series to measure respective voltages of the battery cells. The voltage measuring apparatus includes a sample/hold amplifier configured to sample and hold positive electrode and negative electrode voltages of the battery cells to generate first and second output voltages, a differential voltage converter configured to generate a battery cell voltage according to a voltage difference between a positive input terminal and a negative input terminal, and a switching unit configured to control the first and second output voltages and connection between the positive input terminal and the negative input terminal so that a polarity of the voltage difference is constant. The sample/hold amplifier electrically insulates the switching unit from the battery cells.

Claims

1. A voltage measuring apparatus coupled to a plurality of battery cells coupled to each other in series to measure respective voltages of the battery cells, the voltage measuring apparatus comprising:

a sample/hold amplifier configured to sample and hold positive electrode and negative electrode voltages of the battery cells to generate first and second output voltages;

a differential voltage converter configured to generate a battery cell voltage according to a voltage difference between a positive input terminal and a negative input terminal; and

a switching unit configured to control the first and second output voltages and connection between the positive input terminal and the negative input terminal so that a polarity of the voltage difference is constant,

wherein the sample/hold amplifier electrically insulates the switching unit from the battery cells.

2. The voltage measuring apparatus of claim 1, wherein the sample/hold amplifier,

is configured to hold an input of a first input terminal in a first output node to generate the first output voltage and to hold an input of a second input terminal in a second output node to generate the second output voltage,

wherein the input of the first input terminal is a voltage obtained by sampling a voltage at one of a positive electrode and a negative electrode of a first battery cell among the battery cells, and

the input of the second input terminal is a voltage obtained by sampling a voltage at a remaining one of the positive electrode and the negative electrode of the first battery cell.

3. The voltage measuring apparatus of claim 2, wherein:

the switching unit,

when the input of the first input terminal is a voltage obtained by sampling a positive electrode voltage of the first battery cell, and the input of the second input terminal is a voltage obtained by sampling a negative electrode voltage of the first battery cell,

is configured to couple the positive input terminal to the first output node and to couple the negative input terminal to the second output node.

4. The voltage measuring apparatus of claim 2, wherein:

the switching unit,

when the input of the first input terminal is a voltage by sampling a negative electrode of the first battery cell, and the input of the second input terminal is a voltage obtained by sampling a positive electrode voltage of the first battery cell,

is configured to couple the positive input terminal to the second output node and to couple the negative input terminal to the first output node.

5. The voltage measuring apparatus of claim 2, further comprising:

a first multiplexer including a first switch coupled to the positive electrode of the first battery cell; and

a second multiplexer including a second switch coupled to the negative electrode of the first battery cell.

6. The voltage measuring apparatus of claim 5, wherein

the first switch is coupled to a negative electrode of a second battery cell of the battery cells close to the positive electrode of the first battery cell.

7. The voltage measuring apparatus of claim 5, wherein the second switch is coupled a positive electrode of a third battery cell of the battery cells close to the negative electrode of the first battery cell.

8. The voltage measuring apparatus of claim 1, wherein the sample/hold amplifier comprises:

a first sampling capacitor including one electrode coupled to the first node;

a second sampling capacitor including one electrode coupled to the second node;

an operational amplifier including a first input terminal coupled to another electrode of the first sampling capacitor, a second input terminal coupled to another electrode of the second sampling capacitor, a first output node to which the first output voltage is applied, and a second output node to which the second output voltage is applied;

a first holding capacitor and a first sample/hold switch coupled between the first input terminal and the first output node;

a second holding capacitor and a second sample/hold switch coupled between the second input terminal and the second output node; and

a third sample/hold switch coupled between the first node and the second node,

wherein the first node and the second node are coupled to a corresponding one of a positive electrode and a negative electrode of the first battery among the battery cells.

9. The voltage measuring apparatus of claim 8, wherein:

during a first period when the operational amplifier serves as a voltage follower,

voltages are sampled in the first sampling capacitor and the second sampling capacitor, respectively,

the operational amplifier amplifies a voltage difference between the first input terminal and the second input terminal after the first period.

10. The voltage measuring apparatus of claim 8, wherein:

when the first node is coupled to the positive electrode of the first battery cell, and the second node is coupled to the negative electrode of the first battery cell,

during an on period of the first sample/hold switch and the second sample/hold switch,

the first sampling capacitor samples a positive electrode voltage of the first battery cell, and the second sampling capacitor samples a negative electrode voltage of the first battery cell,

the first sample/hold switch and the second sample/hold switch are turned-off, during an on period of the third sample/hold switch,

a voltage sampled in the first sampling capacitor is held as the first output voltage by the first holding capacitor, and a voltage sampled in the second sampling capacitor is held as the second output voltage by the second holding capacitor.

11. The voltage measuring apparatus of claim 8, wherein:

when the first node is coupled to the negative electrode of the first battery cell, and the second node is coupled to the positive electrode of the first battery cell,

during an on period of the first sample/hold switch and the second sample/hold switch,

the first sampling capacitor samples a negative electrode voltage of the first battery cell, and the second sampling capacitor samples a positive electrode voltage of the first battery cell,

the first sample/hold switch and the second sample/hold switch are turned-off, during an on period of the third sample/hold switch,

a voltage sampled in the first sampling capacitor is held as the first output voltage by the first holding capacitor, and a voltage sampled in the second sampling capacitor is held as the second output voltage by the second holding capacitor.

12. The voltage measuring apparatus of claim 8, wherein the third sample/hold switch is turned off during a period while a positive electrode voltage of the first battery cell is sampled by the first sampling capacitor and the second sampling capacitor.

13. The voltage measuring apparatus of claim 1, wherein the switching unit comprises:

a first connection switch coupled between the first output voltage and the positive input terminal;

a second connection switch coupled between the first output voltage and the negative input terminal;

a third connection switch coupled between the second output voltage and the positive input terminal; and

a fourth connection switch coupled between the second output voltage and the negative input terminal.

14. The voltage measuring apparatus of claim 13, wherein:

when the first output voltage is a voltage obtained by sampling a positive electrode voltage of a first battery cell among the battery cells, and the second output voltage is a voltage obtained by sampling a negative electrode voltage of the first battery cell,

the first connection switch and the fourth connection switch are turned-on, and the second connection switch and the third connection switch are turned-off.

15. The voltage measuring apparatus of claim 13, wherein:

when the first output voltage is a voltage obtained by sampling a negative electrode voltage of a first battery cell among the battery cells, and the second output voltage is a voltage obtained by sampling a positive electrode voltage of the first battery cell,

the first connection switch and the fourth connection switch are turned-off, and the second connection switch and the third connection switch are turned-on.

16. A battery management system for managing a battery pack including a plurality of battery cells coupled to each other in series, the battery management system comprising:

a voltage measuring device including a first node coupled to one of positive electrodes and negative electrodes of one battery cell among the battery cells, and a second node coupled to a remaining one of the positive electrodes and the negative electrodes of the battery cell, and configured to sample a voltage of the first node and a voltage of the second node to measure the battery cell voltage according to a difference between the sampled voltage of the first node and the sampled voltage of the second node; and

a controller configured to receive the battery cell voltage from the voltage measuring apparatus to control charge and discharge of the battery pack,

wherein the voltage measuring apparatus comprises;

a sample/hold amplifier configured to sample and hold the voltage of the first node to generate the first output voltage and to sample and hold the voltage of the second node to generate the second output voltage; and

a switching unit configured to control connections between third and fourth nodes and the first and second output voltages according to a polarity of the battery cell to which the first node and the second node are coupled,

wherein the sample/hold amplifier electrically insulates the switching unit from the battery cells.

17. The battery management system of claim 16, wherein the voltage measuring apparatus further comprises:

a differential voltage converter including a positive input terminal coupled to the third node and a negative input terminal coupled to the fourth node, and configured to generate the battery cell voltage according to a voltage difference between the positive input terminal and the negative input terminal.

18. The battery management system of claim 16, wherein the sample/hold amplifier comprises:

a first sampling capacitor including one electrode coupled to the first node;

a second sampling capacitor including one electrode coupled to the second node;

an operational amplifier including a first input terminal coupled to another electrode of the first sampling capacitor, a second input terminal coupled to another electrode of the second sampling capacitor, a first output node to which the first output voltage is applied, and a second output node to which the second output voltage is applied;

a first holding capacitor and a first sample/hold switch coupled between the first input terminal and the first output node;

a second holding capacitor and a second sample/hold switch coupled between the second input terminal and the second output node; and

a third sample/hold switch coupled between the first node and the second node.

19. The battery management system of claim 18, wherein:

when the first node is coupled to a positive electrode of the battery cell, and the second node is coupled to a negative electrode of the battery cell,

during an on period of the first sample/hold switch and the second sample/hold switch,

the first sampling capacitor samples a positive electrode voltage of the battery cell, and the second sampling capacitor samples a negative electrode voltage of the battery cell,

the first sample/hold switch and the second sample/hold switch are turned-off, during an on period of the third sample/hold switch,

a voltage sampled in the first sampling capacitor is held as the first output voltage by the first holding capacitor, and a voltage sampled in the second sampling capacitor is held as the second output voltage by the second holding capacitor.

20. The battery management system of claim 18, wherein:

when the first node is coupled to a negative electrode of the first battery cell, the second node is coupled to a positive electrode of the first battery cell,

during an on period of the first sample/hold switch and the second sample/hold switch,

the first sampling capacitor samples a negative electrode voltage of the battery cell, and the second sampling capacitor samples a positive electrode voltage of the battery cell,

the first sample/hold switch and the second sample/hold switch are turn-off, during the third sample/hold switch,

a voltage sampled in the first sampling capacitor is held as the first output voltage by the first holding capacitor, and a voltage sampled in the second sampling capacitor is held as the second output voltage by the second holding capacitor.