Battery protection system and process for charging a battery

• US 5,920,181 A
• Filed: 06/24/1998
• Issued: 07/06/1999
• Est. Priority Date: 04/07/1997
• Status: Expired due to Term

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Stockstad, Troy L., Alberkrack, Jade
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Toatley, Gregory J.
• Application Number:
  US09/103,826
• Time in Patent Office: 377 Days
• Field of Search: 320/162, 320/139, 320/146
• US Class Current: 320/146
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A battery protection system (20) controls a process for charging a battery pack (15). A hysteresis comparator (54) senses a charging current flowing through the battery pack (15) and switches off a charging switch (31) to interrupt the charging current when the charging current reaches an upper limit. A transient current is then generated by an inductor (34). The hysteresis comparator (54) senses the transient current flowing through the battery pack (15) and switches on the charging switch (31) to regenerate the charging current when the transient current decreases substantially to zero. Periodically, a battery monitoring circuit (40) switches off the charging switch (31) and measures an open circuit voltage across each battery cell in the battery pack (15). In response to the open circuit voltage of a battery cell reaching a fully charged voltage, the battery monitoring circuit (40) switches off the charging switch (31) to terminate the charging process.

Claims

1. A process for charging a battery, comprising the steps of:

generating a first current flowing through the battery;

interrupting the first current in response to the first

current being greater than a first current value;

inducing a second current flowing through the battery in

response to the first current being interrupted;

regenerating the first current in response to the second

current being less than a second current value, the second current value being smaller than the first current value;

sensing a voltage across the battery; and

repeating the steps of generating the first current, interrupting the first current, inducing the second current, and regenerating the first current in response to the voltage being less than a voltage value.

2. The process as claimed in claim 1, wherein:

the step of generating a first current further includes the step of generating an electromagnetic energy from a portion of an electrical energy in the first current; and

the step of inducing a second current includes inducing the second current by releasing the electromagnetic energy.

3. The process as claimed in claim 1, wherein the step of inducing a second current further includes establishing a conduction path from a negative terminal of the battery to a positive terminal of the battery via a rectifier.

4. The process as claimed in claim 1, wherein the step of sensing a voltage across the battery includes sensing a voltage across a battery cell of a plurality of serially coupled battery cells in the battery.

5. The process as claimed in claim 1, wherein the step of sensing a voltage across the battery further includes the steps of:

interrupting the first current; and

sensing an open circuit voltage of across a battery cell of a plurality of serially coupled battery cells in the battery when the second current is substantially zero.

6. The process as claimed in claim 1, wherein the step of sensing a voltage across the battery includes periodically sensing the voltage across the battery.