Electricity: measuring and testing – Electrolyte properties – Using a battery testing device
Reexamination Certificate
2001-11-02
2003-10-28
Le, N. (Department: 2858)
Electricity: measuring and testing
Electrolyte properties
Using a battery testing device
C324S073100, C324S701000, C324S649000
Reexamination Certificate
active
06639409
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery voltage measurement device for measuring a voltage of stacked rechargeable batteries (a battery pack) which is mounted in an apparatus driven by the rechargeable batteries, such as an electric vehicle or the like.
2. Description of the Related Art
As a low-pollution vehicle designed for the purpose of solving environmental problems and energy problems, an electric vehicle such as an HEV (hybrid electric vehicle) and a PEV (pure electric vehicle) has received a great deal of attention up to the present. The electric vehicle has rechargeable batteries mounted therein, and the electric power of the rechargeable batteries drives an electric motor so as to run the electric vehicle. The electric vehicle has a high-voltage circuit for driving the electric motor and a low-voltage circuit for driving various electronic devices such as acoustic equipment, lighting devices, and an electronic controller (e.g., ECU; electronic control unit). The high-voltage circuit includes an inverter for driving an electric motor, and the inverter controls and drives the electric motor.
In a battery control section of such an electric vehicle, in order to obtain an output state of the rechargeable batteries which stably supplies electric power to the electric motor, it is necessary to use a battery voltage measurement device to accurately measure a battery voltage of each battery block of the battery pack.
FIG. 4
is a circuit diagram illustrating an exemplary structure of a conventional battery voltage measurement device
100
. In
FIG. 4
, the battery voltage measurement device
100
includes: a plurality of switches
120
in which each pair of adjacent switches
120
sequentially selects two corresponding output terminals
111
a
of a battery block
111
included in a battery pack
110
; a capacitor
130
for storing (copying) a designated battery voltage; switches
140
for selectively applying the battery voltage stored in the capacitor
130
to a differential amplifier
150
; the differential amplifier
150
for differentially amplifying the stored battery voltage which is input thereto via the switches
140
; and an A/D converter
160
for performing an A/D conversion of the voltage output from the differential amplifier
150
.
The battery pack
110
includes a plurality of serially-connected battery blocks
111
. A value of a voltage output from one battery block
111
(battery module) is, for example, about DC 20 V. The maximum value of a voltage output from all of the serially-stacked battery blocks
111
is about DC 400 V.
Each pair of adjacent switches
120
is connected to the two corresponding output terminals
111
a
of each of the plurality of battery blocks
111
.
The capacitor
130
has electrodes connected to a pair of conductor lines
141
a
and
141
b
laid between the switches
120
and the switches
140
. The capacitor
130
temporarily stores a battery voltage of each of the battery blocks
111
, which is transferred via two designated switches
120
to the capacitor
130
.
Each of the switches
140
is connected to one of the two input terminals of the differential amplifier
150
and serves to connect the differential amplifier
150
to the capacitor
130
or disconnect the differential amplifier
150
from the capacitor
130
. On/Off control of the plurality of switches
120
and the switches
140
is performed by a switching controller (not shown), e.g., a microcomputer.
With the above-described structure, at first, in order to store (copy) a battery voltage of a first battery block
111
in (into) the capacitor
130
, each of the switches
120
connected to one of the two output terminals
111
a
of the first battery block
111
is turned on. At this time, the switches
140
are turned off to disconnect the capacitor
130
from both of the two input terminals of the differential amplifier
150
.
Next, all the switches
120
are turned off to disconnect the capacitor
130
from all of the battery blocks
111
, and then the switches
140
are turned on so as to input the battery voltage of the first battery block
111
, which is stored in the capacitor
130
, to the differential amplifier
150
. Data corresponding to the battery voltage differentially-amplified, for example, from DC 20 V to DC 5 V in an input voltage range of the A/D converter
160
, by the differential amplifier
150
is A/D-converted by the A/D converter
160
. The A/D-converted battery voltage data is read by, for example, a microcomputer (not shown) in a subsequent stage.
However, in the conventional battery voltage measurement device
100
, in the case where the battery voltage of the designated battery block
111
is stored in the capacitor
130
and all of the switches
120
are turned off at the time of measuring the battery voltage, when the switches
140
are turned on, a voltage of up to approximately DC 400 V is applied to the plurality of switches
120
which are turned off. Thus, the plurality of switches
120
are required to withstand a voltage of DC 400 V or more. Accordingly, the plurality of switches
120
are required to be large-sized expensive switches which withstand a high voltage and the number of those switches is required to be at least as many as the number of all the output terminals of the battery blocks
111
.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a battery voltage measurement device includes: a plurality of first switching sections, in which each pair of adjacent first switching sections sequentially selects two output terminals of each of a plurality of battery blocks included in a battery pack so that each of the selected output terminals are connected to one of a pair of conductor wires; a voltage detection section for detecting a battery voltage of each of the plurality of battery blocks via the pair of conductor wires; and second switch sections each being provided on a respective one of the pair of conductor lines and being serially connected to each group of the plurality of first switch sections connected in parallel to one of the pair of conductor lines.
With the above-described structure, by providing the series circuit in which the plurality of the first switching sections are connected to the second switching sections, the voltage of up to approximately DC 400 V applied to the first and second switching sections being in an off state, is applied to the first and second switching sections as voltages divided by the respective parasitic capacitance of the first and second switching sections being in an off state, so that the voltage applied to the first and second switching section can be lowered. Thus, small-sized inexpensive switches only required to withstand a voltage which is lower than that conventionally-required to withstand can be used as the first and second switching sections. Although the first switching sections are conventionally required to withstand a voltage of DC 400 V or more, by equalizing the respective parasitic capacitance of the first and second switching sections, a voltage which the first and second switching sections are required to withstand can be lowered to approximately DC 200 V. Moreover, by controlling the parasitic capacitance of the first and second switching sections, a voltage which the first switching sections are required to withstand can be lowered and an electric circuit of the voltage measurement section can be structured (as an IC chip) using a conventional IC process.
According to one embodiment of the invention, the battery voltage measurement device may further include: a capacitance section laid between the pair of conductor lines for selectively storing a battery voltage of each of the battery blocks via the first and second switching sections; and a third switching section for selectively applying the battery voltage stored in the capacitance section to the voltage detection section, in which the voltage detection section may detect the battery voltage stored in the capacitance section vi
Maki Ichiro
Morimoto Naohisa
Yudahira Hirofumi
Le N.
Nguyen Vincent Q.
Snell & Wilmer LLP
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