Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
1999-03-16
2001-06-26
Wong, Peter S. (Department: 2426)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C324S429000
Reexamination Certificate
active
06252376
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery-state monitoring system for monitoring the states of battery modules, which is adaptable for a battery system using a battery group having a plurality of battery modules.
2. Description of the Related Art
There is known a battery system using a battery group which consists of a plurality of battery modules connected in series or parallel fashion. An example of the battery system is a battery system for an electric vehicle. It is feared that a reliability of the system is deteriorated when the battery capacities, voltages and temperatures of the battery modules vary in their values. As a result, it is necessary to detect the current states of each battery module on its capacity, voltages and temperature, and to check whether or not the states of the battery modules are correct. Thus, a battery-state monitoring system is used for monitoring the current states of the battery modules.
In an example of the battery-state monitoring system, sensors are respectively provided for the battery modules to detect the current states of those modules, and are electrically connected to a management unit by signal lines. The management unit processes signals received from the sensors, and checks whether or not the current states of the battery modules are correct.
In the thus constructed battery-state monitoring system, a number of sensors are provided while being respectively associated with the battery modules, and connected to the management unit via signal lines. Therefore, a great number of the signal lines are required for their connection, and the wiring of the system is complicated. The wiring complexity leads to deterioration of the system reliability.
On the other hand, the system for monitoring battery states may be arranged such that battery-state monitoring units are respectively provided for the battery modules, and those units are connected to a management unit by two signal lines. In the battery-state monitoring system, communication on the units, are performed between the battery-state monitoring units and the management unit by use of a specific communication protocol. This monitoring system indeed succeeds in considerably simplifying the system wiring; however, it presents another problem. A control for controlling the data communication between the battery-state monitoring units and the management unit is indispensable to the monitoring system. The communication control is comparable with a LAN, and very complicated.
SUMMARY OF THE INVENTION
It is an object of the present invention is to provide a battery-state monitoring system for a battery group which simplifies the wiring of the system and a communication control arrangement.
A battery-state monitoring system for a battery group according to the present invention, comprises: a plurality of module monitoring units each comprising battery-state detecting means for detecting at least one state of each of plural battery modules forming a battery group; a switching element which turns on when the state of the battery module, detected by the battery-state detecting means, is a predetermined state, and turns off when the state is a state different from the predetermined state; and current detecting means connected in series or parallel to the switching element; two signal lines connecting the switching elements of the plurality of module monitoring units in series; and a management unit comprising first means for supplying alternate current to the two signal lines; and second means for detecting as to whether the circuit including the two signal lines is opened or closed, the management unit judging the states of the plurality of battery modules by the result of the detecting operation by the second means.
With such an arrangement, when the battery modules are all put in a normal state, the switching elements contained in all the module monitoring units are turned off. Therefore, the management unit detects that the circuit including the two signal lines is closed, and judges that all the battery modules are normal, from the detection result. When at least one battery module is not in the predetermined state, the switching element of at least one module monitoring unit is turned off. Therefore, the management unit detects that the circuit including the two signal lines is opened, and judges that at least one battery module is abnormal, from the detection result.
In the arrangement of the battery-state monitoring system, only two signal lines are used for connecting a plurality of module monitoring units to the management unit. The wiring of the system is simplified. Further, the battery-state monitoring system thus arranged can monitor the states of the battery modules in the following simple manner: each module monitoring unit turns on or off the phototransistor of the photocoupler contained therein in accordance with the states of the battery module
1
associated therewith, and the management unit detects that the circuit including the signal lines is closed or opened. This technical feature simplifies the communication control arrangement.
The battery-state monitoring system arranged as described above may further include mode select means for selecting a sleep mode to reduce power consumption by making invalid most of the functions of the module monitoring unit, or a normal mode to allow the module monitoring units to normally operate. The mode select means changes the operation mode of the module monitoring unit from the sleep mode to the normal mode in response to a start-up signal from the management unit. In the battery-state monitoring system, the switching element may be of the normal-on type, and hence it is turned on when receiving no control signal, and turned off when receiving a control signal.
In the battery-state monitoring system, the module monitoring units may time sequentially turn on or off the switching elements at predetermined time intervals in accordance with states representative of a plurality of characteristics of each battery module.
As seen from the foregoing description, the battery-state monitoring system for a battery group includes a plurality of module monitoring units each including a switching element which turns on when the state of the battery module is a predetermined state, and turns off when the state is a state different from the predetermined state, two signal lines connecting the switching elements of the plurality of module monitoring units in series; and a management unit for judging the states of the plurality of battery modules by the result of detecting as to whether the circuit including the two signal lines is opened or closed. Therefore, the battery-state monitoring system succeeds in simplifying the wiring of the system and a communication control arrangement.
REFERENCES:
patent: 5422558 (1995-06-01), Stewart
patent: 5850351 (1998-12-01), Lofty et al.
Nakamura Hideji
Ueda Kiyoshi
Japan Storage Battery Co., Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Toatley , Jr. Gregory J.
Wong Peter S.
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