Battery system and electric vehicle using the battery system

• US 6,262,561 B1
• Filed: 12/23/1998
• Issued: 07/17/2001
• Est. Priority Date: 12/26/1997
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kumashiro, Yoshiaki, Takahashi, Tadashi, Emori, Akihiko, Miyazaki, Hideki
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US09/219,433
• Time in Patent Office: 937 Days
• Field of Search: 320/104, 320/118, 320/122
• US Class Current: 320/104
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• 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: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A battery system includes a battery assembly having a plurality of modules, which are controlled by a system control circuit, each module including a module control circuit and a module by-pass circuit which is controlled via the module control circuit so as to suppress the charging variation among the plurality of modules. Each control circuit and the system-controlling circuit are connected to each other via a bilateral transmission medium and each module by-pass circuit is controlled based on information bilaterally transmitted between each module control circuit and the system control circuit via the bilateral transmission medium.

Claims

1. A battery system, including a battery assembly that includes a plurality of modules, each of which includes a plurality of battery cells serially connected to each other for driving electrical loads by performing charging and discharging operations, and which is controlled by a system-controlling unit;

wherein each module includes measuring means for measuring voltage of each module, a module-controlling unit for transmitting a value of said measured voltage of said module to said system-controlling unit and for receiving a reference voltage value which is set in said system-controlling unit, and a module by-pass device connected to each module in parallel, which is situated for by-passing a part of the charging current for said module, and module-by-passing device-drive means for driving said module by-pass device based on a result of comparison between said measured voltage of said module and said reference voltage value; and

wherein each battery cell includes a battery cell by-passing device connected to each battery cell in each module in parallel, which is situated for by-passing a part of the charging current for said battery cell, and battery cell by-passing device-drive means for turning on said battery cell by-passing device based on a variation in voltage values among battery cells in said module.

2. A battery system according to claim 1, wherein said module-controlling unit in each module includes at least one microcomputer and receives power from said serially connected battery cells in said module, and wherein bilateral transmission between said microcomputer and said system-controlling unit is performed via an electrical isolation device.

3. A battery system according to claim 1, wherein the battery cell by-passing devices which are provided in each module, and controlled by a control signal sent from said system-controlling unit are used for suppressing charging variation among said plurality of battery cells in said module, and are also used for suppressing charging variation among said plurality of modules.

4. An electric vehicle using a battery system according to claim 1, wherein each of said module-controlling circuits controls said battery cells in their corresponding module, with each said module-controlling circuit including at least one microcomputer and receiving power from said corresponding module;

and

wherein bilateral transmission between each module-controlling circuit and said system-controlling circuit is performed via an electrical isolation device.

5. A battery system, including a battery assembly that includes a plurality of modules, each of which includes a plurality of battery cells serially connected to each other, and which is controlled by a system-controlling unit;

wherein each module includes a measuring unit which measures voltage of each module, a module-controlling unit which transmits a value of said measured voltage of said module to said system-controlling unit and which receives a reference voltage value which is set in said system-controlling unit, and a module by-pass device connected to each module in parallel, which by-passes at least a part of the charging current for said module, and module by-passing device-drive means which drive said module by-pass device based on a result of comparison between said measured voltage of said module and said reference voltage value; and

wherein each battery cell includes a cell by-passing device connected to each battery cell in each module in parallel, which by-passes a part of the charging current for said battery cell, and a battery cell by-passing device-drive device which turns on said battery cell by-passing device based on a variation in voltage values among battery cells in said module.