Protection device for assembled battery, and battery pack unit

• US 7,973,534 B2
• Filed: 03/17/2008
• Issued: 07/05/2011
• Est. Priority Date: 03/28/2007
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Tohiba
• Inventors: Shibuya, Nobuo, Harada, Yasuhiro, Takami, Norio, Tatebayashi, Yoshinao
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): OMAR, AHMED H
• Application Number:
  US12/049,688
• Publication Number:
  US 20080239628A1
• Time in Patent Office: 1,205 Days
• Field of Search: 324/433, 320/132
• US Class Current: 324/433
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A protection device for an assembled battery includes a sampling unit which individually samples voltages of batteries of the assembled battery to generate sampled voltages, a holding unit which holds the sampled voltages to generate a plurality of holding voltages, a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node, a measuring unit configured to measure the individual voltages and the state of charges of the batteries based on a voltage of the node in a measuring period within a constant measuring cycle, and a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period.

Claims

1. A protection device for an assembled battery including a plurality of secondary batteries connected in series, the protection device comprising:

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and a state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period,

wherein the sampling unit further includes a plurality of discharge switches for discharging charges of a plurality of capacitors, and

wherein the control unit includes a determining unit to determine an overcharged cell based on the individual voltages of the batteries and a selecting unit to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches in the term other than the measuring period and turns on the selected sample switch, turns off the selected sample switch, turns on the discharge switch which discharges a charge of a capacitor corresponding to the overcharged cell, and turns off the discharge switch in that order.

2. The device according to claim 1, wherein the control unit is configured to control the sample switches to satisfy a condition of T0>

Td>

0.5T0 when the measuring cycle is T0 and a time interval from a current termination time of the repeated on/off operation up to a initiation time of a next measuring period of the repeated on/off operation is Td.

3. A protection device for an assembled battery including a plurality of secondary batteries connected in series, the protection device comprising:

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and the state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period, wherein

the measuring unit is configured to measure the state of charge including the individual voltages of the batteries and a state-of-charge deviation among the secondary batteries,

the protection device further comprises a memory which stores the state-of-charge deviation when a preliminarily determined state-of-charge deviation detection event is detected,

the control unit is configured to turn on/off at least one sample switch selected within the term other than the measuring period the number of times of increase corresponding to the stored state-of-charge deviation,

the state-of-charge deviation detection event is detected when a charging/discharging current is I≦

I0 and a voltage maximum value of the battery is Vcmax>

V0, where I indicates the charging/discharging current, Vcmax indicates the voltage maximum value, I0 indicates an arbitrary current value which satisfies a condition of I0 ≦

20 [mV]/Rdc [mΩ

] when a DC impedance of the battery is Rdc [mΩ

] at 25°

C.; and

V0 indicates an arbitrary voltage in a range of V1≦

V0≦

VH, where V1 is a cell voltage in a case where a voltage change rate A [V/ % SOC] to the cell capacity reaches A=20 [mV/ % SOC] from A <

20 [mV/ % SOC] under a condition that constant current charge of 1 C is executed at 25°

in the battery, and VH is a fully charging voltage of the battery.

4. The device according to claim 3, wherein the control unit includes a determining unit to determine an overcharged cell from the individual voltages of the secondary batteries, and a selecting unit to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches and turn on/off the selected sample switch the number of times.

5. A protection device for an assembled battery including a plurality of secondary batteries connected in series, the protection device comprising:

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and the state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period, wherein

the measuring unit is configured to measure the state of charge including individual voltages of the batteries and a state-of-charge deviation among the batteries,

the control unit is configured to repeatedly turn on/off at least one sample switch selected each time when a preliminarily determined state-of-charge deviation detection event is detected, and

the state-of-charge deviation detection event is detected when a charging/discharging current is I≦

I0 and a voltage maximum value of the battery is Vcmax>

V0, where I indicates the charging/discharging current;

Vcmax indicates the voltage maximum value, I0 indicates an arbitrary current value which satisfies a condition of I0≦

20 [mV]/Rdc [mΩ

] when a DC impedance of the battery is Rdc [mΩ

] at 25°

C.; and

V0 indicates an arbitrary voltage in a range of V1≦

V0≦

VH, where V1 is a cell voltage in a case where a voltage change rate A [V/ % SOC] to the cell capacity reaches A=20 [mV/ % SOC] from A<

20 [mV/ % SOC] under a condition that constant current charge of 1 C is executed at 25°

in the battery, and VH is a fully charging voltage of the battery.

6. The device according to claim 5, wherein the control unit includes a determining unit to determine an overcharged cell based on the individual voltages of the batteries and a selecting unit to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches and turn on/off the selected sample switch.

7. A battery pack unit comprising:

an assembled battery including a plurality of secondary batteries connected in series;

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and the state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period, wherein

the sampling unit further includes a plurality of discharge switches for discharging charges of a plurality of capacitors,

the control unit includes a determining unit to determine an overcharged cell based on the individual voltages of the batteries and a selecting unit to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches in the term other than the measuring period and turns on the selected sample switch, turns off the selected sample switch, turns on the discharge switch which discharges a charge of a capacitor corresponding to the overcharged cell, and turns off the discharge switch in that order.

8. The battery pack according to claim 7, wherein the control unit is configured to control the sample switches to satisfy a condition of T0>

Td>

0.5T0 when the measuring cycle is T0 and a time interval from a current termination time of the repeated on/off operation up to a initiation time of a next measuring period of the repeated on/off operation is Td.

9. A battery pack unit, comprising:

an assembled battery including a plurality of secondary batteries connected in series;

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and a state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period, wherein

the measuring unit is configured to measure the state of charge including the individual voltages of the batteries and a state-of-charge deviation among the secondary batteries,

the protection device further comprises a memory which stores the state-of-charge deviation when a preliminarily determined state-of-charge deviation detection event is detected,

the control unit is configured to turn on/off at least one sample switch selected within the term other than the measuring period the number of times of increase corresponding to the stored state-of-charge deviation, and

the state-of-charge deviation detection event is detected when a charging/discharging current is I≦

I0 and a voltage maximum value of the battery is Vcmax>

V0, where I indicates the charging/discharging current, Vcmax indicates the voltage maximum value, I0 indicates an arbitrary current value which satisfies a condition of I0≦

20 [mV]/Rdc [mΩ

] when a DC impedance of the battery is Rdc [mΩ

] at 25°

C.; and

V0 indicates an arbitrary voltage in a range of V1≦

V0≦

VH, where V1 is a cell voltage in a case where a voltage change rate A [V/ % SOC] to the cell capacity reaches A=20 [mV/ % SOC] from A<

20 [mV/ % SOC] under a condition that constant current charge of 1 C is executed at 25°

in the battery, and VH is a fully charging voltage of the battery.

10. The battery pack according to claim 9, wherein the control unit includes a function of determining an overcharged cell from the individual voltages of the secondary batteries, and the control unit is configured to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches and turn on/off the selected sample switch the number of times.

11. A battery pack unit, comprising:

an assembled battery including a plurality of secondary batteries connected in series;

a sampling unit which includes a plurality of sample switches and individually samples voltages of the batteries using the sample switches to generate a plurality of sampled voltages;

a holding unit which holds the sampled voltages to generate a plurality of holding voltages;

a multiplexer which sequentially reads the holding voltages and outputs each voltage to a common output node;

a measuring unit configured to measure the individual voltages and a state of charges of the batteries based on a voltage of the common output node in a measuring period within a constant measuring cycle; and

a control unit configured to turn on/off the sample switches at the same time within the measuring period and repeatedly turn on/off at least one sample switch selected from the plurality of sample switches in accordance with the state of charge in a term other than the measuring period, wherein

the measuring unit is configured to measure the state of charge including individual voltages of the batteries and a state-of-charge deviation among the batteries,

the control unit is configured to repeatedly turn on/off at least one sample switch selected each time when a preliminarily determined state-of-charge deviation detection event is detected, and

the state-of-charge deviation detection event is detected when a charging/discharging current is I≦

I0 and a voltage maximum value of the battery is Vcmax>

V0, where I indicates the charging/discharging current, Vcmax indicates the voltage maximum value, I0 indicates an arbitrary current value which satisfies a condition of I0≦

20 [mV]/rdc [mΩ

] when a DC impedance of the battery is Rdc [mΩ

] at 25°

C.; and

V0 indicates an arbitrary voltage in a range of V1≦

V0≦

VH, where V1 is a cell voltage in a case where a voltage change rate A [V/ % SOC] to the cell capacity reaches A=20 [mV/ % SOC] from A <

20 [mV/ % SOC] under a condition that constant current charge of 1 C is executed at 25°

in the battery, and VH is a fully charging voltage of the battery.

12. The battery pack according to claim 11, wherein the control unit determines an overcharged cell based on the individual voltages of the batteries, and the control unit is configured to select at least one sample switch corresponding to the overcharged cell from the plurality of sample switches and turn on/off the selected sample switch.