Protective device and protective system for battery assembly which detects discontinuities through voltage monitoring

• US 9,837,837 B2
• Filed: 11/15/2013
• Issued: 12/05/2017
• Est. Priority Date: 11/19/2012
• Status: Active Grant

• Current Assignee: BYD Semiconductor Co., Ltd. (BYD Company Limited)
• Original Assignee: BYD Company Limited
• Inventors: Wang, Xiaoping, Bai, Qinggang
• Primary Examiner(s): Grant, Robert
• Assistant Examiner(s): TRISCHLER, JOHN T
• Application Number:
  US14/437,301
• Publication Number:
  US 20150280469A1
• Time in Patent Office: 1,481 Days
• Field of Search: 320134
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A protective device and a protective system for a battery assembly are provided. The battery assembly comprises N cells, and the protective device includes: a constant current source module comprising M (1<M≦N) first constant current sources connected in parallel with M cells in the N cells respectively, and configured to generate an output current according to a voltage of the connected cell; a voltage sampling module including N voltage sampling units connected in parallel with the N cells respectively and configured to output a sampling voltage; a determining module connected with the voltage sampling module and configured to generate a first disconnection signal when the sampling voltage output from any voltage sampling unit reaches a predetermined value; and a protective control module, connected with the determining module and configured to control the battery assembly to turn off according to the first disconnection signal.

Claims

1. A protective device for a battery assembly, wherein the battery assembly comprises N cells, N is an integer greater than 2, and the protective device comprises:

a constant current source module comprising M first constant current sources, the M first constant current sources being connected in parallel with M cells in the N cells respectively, and configured to generate an output current according to a voltage of the connected cell, wherein M is a positive integer smaller than N;

a voltage sampling module comprising N voltage sampling units, the N voltage sampling units being connected in parallel with the N cells respectively and configured to output a sampling voltage;

a determining module connected with the voltage sampling module and configured to generate a first disconnection signal when the sampling voltage outputted from any one of the N voltage sampling units reaches a predetermined value;

a protective control module, connected with the determining module and configured to control the battery assembly to turn off according to the first disconnection signal; and

a level shifting module, connected between the determining module and the protective control module and configured to convert the first disconnection signal to a level shifting signal and to transmit the level shifting signal to the protective control module, wherein the protective control module controls the battery assembly to turn off according to the level shifting signal, wherein

N=2M−

1, and a k^th first constant current source is connected in parallel with a (2k−

1)^th cell, wherein k is an integer ranging from 1 to M; and

when the output current of the k^th first constant current source decreases, the sampling voltage outputted from the (2k−

1)^th voltage sampling unit decreases, and the sampling voltages outputted from the 2k^th and (2k−

2)^th voltage sampling units increase.

2. The protective device according to claim 1, wherein the determining module comprises M−

1 comparators, a first input terminal of a k^th comparator is connected with a predetermined voltage and a second input terminal of the k^th comparator is connected with a 2k^th voltage sampling unit, and when the sampling voltage output from the 2k^th voltage sampling unit is greater than the predetermined voltage, the k^th comparator generates the first disconnection signal.

3. The protective device according to claim 2, wherein when any one of the M−

1 comparators generates the first disconnection signal, the level shifting module generates the level shifting signal.

4. The protective device according to claim 3, wherein each of the N voltage sampling units comprises a first resistor and a second resistor connected in series.

5. The protective device according to claim 4, wherein the second input terminal of the k^th comparator is connected with a first node formed between the first resistor and the second resistor of the 2k^th voltage sampling unit.

6. The protective device according to claim 1, wherein a first connecting wire of the first cell is grounded, and the constant current source module further comprises a second constant current source connected with a first connecting wire of a N^th cell, and a third constant current source connected with a second connecting wire of the N^th cell.

7. The protective device according to claim 6, wherein the constant current source module further comprises:

a plurality of diodes connected in series and connected between the first connecting wire of the N^th cell and the second constant current source; and

a switch transistor connected between the second connecting wire of the N^th cell and the third constant current source and controlled by a voltage at a second node formed between the diode and the second constant current source.

8. The protective device according to claim 7, wherein when the second connecting wire of the N^th cell breaks, a second disconnection signal is outputted from a third node formed between the switch transistor and the third constant current source, and the protective control module controls the battery assembly to turn off according to the second disconnection signal.

9. The protective device according to claim 7, wherein the switch transistor is controlled to be turned on by the voltage at the second node when the first connecting wire and the second connecting wire of the N^th cell are connected with each other.

10. A protective system for a battery assembly, wherein the battery assembly comprises a plurality of cells, and the protective system comprises:

a plurality of filtering and regulating modules connected with the plurality of respectively;

a protective device; and

a switch module connected in series with the battery assembly and controlled by the protective device to turn off when a connecting wire between the plurality of cells and the protective device breaks,

wherein the battery assembly comprises N cells, N is an integer greater than 2, and the protective device further comprises;

a constant current source module comprising M first constant current sources, the M first constant current sources being connected in parallel with M cells in the N cells respectively, and configured to generate an output current according to a voltage of the connected cell, wherein M is a positive integer smaller than N;

a voltage sampling module comprising N voltage sampling units, the N voltage sampling units being connected in parallel with the N cells respectively and configured to output a sampling voltage;

a determining module connected with the voltage sampling module and configured to generate a first disconnection signal when the sampling voltage output from any one of the N voltage sampling units reaches a predetermined value; and

a protective control module connected with the determining module and configured to control the switch module to turn off according to the first disconnection signal.

11. The protective system according to claim 10, the protective device further comprising:

a level shifting module, connected between the determining module and the protective control module and configured to convert the first disconnection signal to a level shifting signal and to transmit the level shifting signal to the protective control module, wherein the protective control module controls the battery assembly to turn off according to the level shifting signal.

12. The protective system according to claim 11, wherein N=2M−

1, and a k^th first constant current source is connected in parallel with a (2k−

1)^th cell, wherein k is an integer ranging from 1 to M.

13. The protective system according to claim 12, wherein:

when the output current of the k^th first constant current source decreases, the sampling voltage outputted from the (2k−

1)^th voltage sampling unit decreases, and the sampling voltages outputted from the 2k^th and (2k−

2)^th voltage sampling units increase.

14. The protective system according to claim 12, wherein:

the determining module comprises M−

1 comparators, a first input terminal of a k^th comparator is connected with a predetermined voltage and a second input terminal of the k^th comparator is connected with a 2k^th voltage sampling unit, and when the sampling voltage output from the 2k^th voltage sampling unit is greater than the predetermined voltage, the k^th comparator generates the first disconnection signal.