Electricity: measuring and testing – Electrolyte properties – Using a battery testing device
Reexamination Certificate
2000-10-17
2001-07-03
Tso, Edward H. (Department: 2838)
Electricity: measuring and testing
Electrolyte properties
Using a battery testing device
C320S116000
Reexamination Certificate
active
06255826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery voltage measuring device which detects the battery voltage in a power source device formed by connecting a plurality of secondary batteries in series, and in particular, relates to a battery voltage measuring device which quickly detects a breakage of the signal line when a signal line for voltage measurement has been broken.
2. Background Art
Conventionally, hybrid vehicles equipped with an electrical motor in addition to an engine as the drive source for driving the vehicle are known.
One type of control (mode) of these hybrid vehicles is the parallel hybrid vehicle that supplements the output of the engine using an electric motor. In this parallel hybrid vehicle, various types of control are carried out. For example, during acceleration, the electrical motor assists the output of the engine, and during deceleration, the battery is charged by deceleration regeneration. Thereby, the state of charge of the battery (that is, the remaining charge of the battery) can be maintained, while at the same time fulfilling the needs of the driver. In addition, because high voltages are required, this battery is formed by connecting a plurality of battery cells in series.
Conventionally, a battery is formed by connecting a plurality of modules in series, and each module is formed by connecting a plurality of cells in series. In the voltage detection of the battery, voltage sensors are attached to each modules and the voltage of each module is detected by respective voltage sensors. In addition, a noise filter formed by a resistors and a capacitor is interposed between each module and each sensor, and these noise filters eliminate the unnecessary noise component from the voltage signal from the battery voltage sent through the signal line. Thereby, a higher precision voltage detection is possible because an averaged voltage is input into the voltage sensor.
However, in the case of using noise filters formed by resistors and a capacitor as described above in a battery voltage measuring device, the problem arises that when a breakage occurs in the voltage measuring line, in the voltage sensor of the broken voltage measuring line, the voltage of the module is divided by the capacitor of the noise filter, and thus accurate detection of the voltage of the module is not possible.
In addition, the other problem arises that the voltage value of the module detected by the voltage sensor does not differ very much from the normal voltage value and thus a breakage occurring in the voltage measuring line cannot be detected.
As described above, in the case that breakage or other failures occur in the signal line, the detected voltage of the module on the broken signal line is different from the actual value, and accurate detection of the module voltage becomes impossible. Because of this, it becomes very important to immediately detect the breakage of this signal line and to take fail-safe actions.
SUMMARY OF THE INVENTION
In consideration of the above described problems, it is an object of the present invention to provide a battery voltage measuring device capable of immediately detecting a breakage in the voltage measuring line in a battery voltage measuring device using a noise filter comprising resistors and a capacitor.
In order to attain the above objective, the present invention provides a battery voltage measuring device (in the embodiment, the battery voltage measuring device
50
) which divides a plurality of secondary batteries (in the embodiment, secondary batteries
30
) connected in series into a plurality of blocks (in the embodiment, modules
10
) constituted at least one battery and measures the voltage of each block, comprising voltage measurement devices (in the embodiment, voltage sensors
20
) provided on each block to measure the voltage of the block, noise filters (in the embodiment what, noise filters
40
) provided before the voltage measurement devices and having capacitor, and measuring line breakage detection resisters (in the embodiment, the measuring line breakage detection resisters
60
) that are interposed between the blocks and the voltage measuring devices, and are connected in parallel to the blocks, wherein the resistance ratio of the measuring line breakage detection resisters corresponding to the adjacent blocks is set at at the value in which the voltage value divided by said measuring line breakage detection resistors at the time of breakage of the measuring line becomes a voltage value not normally detected when the measuring line is not broken.
An example of a conventional battery voltage detection device is shown in FIG.
3
. As shown in this figure, in the conventional battery voltage detection device, voltage sensors
20
are provided for each of the modules
10
, and therebetween, noise filters
40
for eliminating noise are provided. For example, as shown in
FIG. 4
, in a battery voltage detection device having this kind of structure, when a voltage measuring line that carries the difference in voltage between modules to the voltage sensors
20
is broken at point A, the voltage VA of the module
10
-
1
and the voltage VB of module
10
-
2
is divided by the capacitor of the noise filter, the voltage values V1 and V2 detected by voltage sensor
20
-
1
and voltage sensor
20
-
2
deviate from the actual values.
Specifically, the voltage values V1 and V2 detected by the voltage sensor
20
-
1
and the voltage sensor
20
-
2
are:
V1=V2=(VA+VB)/2.
Thus, in the case that a breakage and the like of the signal line occurs, the values of V1 and V2 that are read out become the value which is of sum of VA and VB divided by the capacitor C. In particular, in the low pass filters denoted by
40
in
FIG. 3
, etc., which require maintaining an equivalent time constant at each channel, the values of the capacitors C and the resistors Rs must be equivalent. Thus, these values become values divided by 2 exactly, and then V1≈V2, and the breakage failure cannot be detected.
In addition, under this condition, even if a voltage abnormality in a single module on the broken measuring line occurs, because both voltage values are averaged and an abnormality identification threshold value cannot be effectively used, the detection of an abnormality is difficult.
In contrast, according to the structure of the present invention, by the voltage measuring line breakage detection resistors inserted before each noise filter, in the case that a breakage of the voltage measuring line occurs, the voltage that is in proportion to the resistance ratio of the voltage measurement breakage detection resistor, that is, the voltage value that differs significantly when compared to the normal value, is detected by the voltage sensor, and the breakage in the voltage measuring line can be detected immediately.
In addition, simply by providing this resistor before the above-described noise filters, a complicated circuit becomes unnecessary, and thus breakage of the voltage measuring line can be detected at low cost.
In addition, the measuring line breakage detection resister according to the above-described embodiment preferably is a resistor on the M&OHgr; order.
Because the above measuring line breakage detection resistor is a resistor that shorts each block, because this resistor value is large, the dark current can be reduced to a minimum, and the discharge of the battery during stand-by can be reduced to a minimum. As a result, at the measuring line breakage detection resistor, preferably the largest resistor value that is normally available should be selected.
Furthermore, by using a resistor with a high resistance as the measuring line breakage detection resistor, the electric corrosion of the patterns, elements, etc., of the substrate of the battery voltage measuring device due to dark current can be avoided.
In addition, in the present invention, the resistance ratio of the measuring line breakage detecting resistors corresponding to the adjacent blocks are set within a
Maeda Tomohiko
Ohsawa Naoki
Tsurumi Takafumi
Armstrong Westerman Hattori McLeland & Naughton LLP
Honda Giken Kogyo Kabushiki Kaisha
Tso Edward H.
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