ABNORMALITY DETECTION APPARATUS FOR SECONDARY BATTERY DEVICE

• US 20070164710A1
• Filed: 12/29/2006
• Published: 07/19/2007
• Est. Priority Date: 01/16/2006
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: SATO, Yuji
• Granted Patent: US 7,656,126 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection

Abstract

There is provided an abnormality detection apparatus for a secondary battery device having n secondary batteries (where n is 2 or more) connected in series for obtaining a high battery voltage. The apparatus includes n voltage detecting circuits which outputs high-level signals at a normal voltage between both terminals of each of the n secondary batteries, n N-channel field effect transistors having gates to which outputs of the n voltage detecting circuits are respectively supplied, and n P-channel field effect transistors having gates to which drain voltages of the n N-channel field effect transistors are respectively supplied. In the n P-channel field effect transistors, a drain of a P-channel field effect transistor is connected to a source of the next P-channel field effect transistor successively, thus detecting an abnormality by a voltage obtained at a drain of the n-th P-channel field effect transistor.

Claims

1. An abnormality detection apparatus for a secondary battery device having n secondary batteries (where n is 2 or more) connected in series for obtaining a high battery voltage corresponding to the n secondary batteries, the apparatus comprising:

n voltage detecting circuits which outputs high-level signals at a normal voltage in a range from a lower limit voltage to an upper limit voltage between both terminals of each of the n secondary batteries;

n N-channel field effect transistors having gates to which outputs of the n voltage detecting circuits are respectively supplied; and

n P-channel field effect transistors having gates to which drain voltages of the n N-channel field effect transistors are respectively supplied,

wherein, in the n P-channel field effect transistors, a drain of a 1st P-channel field effect transistor is connected to a source of a 2nd P-channel field effect transistor, and successively a drain of the 2nd P-channel field effect transistor is connected to . . . a source of an n-th P-channel field effect transistor, thus detecting an abnormality by a voltage obtained at a drain of the n-th P-channel field effect transistor.

2. The abnormality detection apparatus according to claim 1, wherein the secondary battery is a lithium ion secondary battery.

3. The abnormality detection apparatus according to claim 1, wherein resistors are connected in parallel, respectively, to the n secondary batteries, and respective series connections of resistors and voltage detecting circuits are connected in parallel, respectively, to the n secondary batteries and the resistors.

4. The abnormality detection apparatus according to claim 1, which is mounted on a battery pack, together with the n secondary batteries.

5. The abnormality detection apparatus according to claim 1, wherein each of the n voltage detecting circuits is constructed so that it obtains a high-level signal at an output terminal at a voltage in a range from a lower limit voltage of 2.5 V of a normal voltage of the n secondary batteries to an upper limit voltage of 4.2 V of a normal voltage and obtains a low-level signal at the output terminal at a voltage which falls outside of the range.

6. The abnormality detection apparatus according to claim 1, wherein output terminals of the n voltage detecting circuits are respectively connected to the gates of the N-channel field effect transistors through respective resistors.