JP4186406B2 - Minimum cell voltage detection circuit for assembled batteries - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a minimum cell voltage detection circuit for an assembled battery.
[0002]
[Prior art]
In vehicles equipped with a high-voltage, large-capacity secondary battery in the form of an assembled battery, it is important for the safety management of the battery to manage each single battery that makes up the assembled battery, especially whether the terminal voltage is too low. is there.
[0003]
For this reason, conventionally, the voltage of each unit cell constituting the assembled battery is selected one by one and sequentially input to the A / D converter to check whether each unit cell voltage is below a predetermined minimum value. It was.
[0004]
[Problems to be solved by the invention]
However, when using the assembled battery power as travel energy, it is usual to configure the assembled battery by connecting several hundred unit cells in series from the viewpoints of reducing wiring power loss and circuit miniaturization.
[0005]
For this reason, a problem arises that it takes time to select and inspect A / D-convert the voltage of such a large number of single cells one by one.
[0006]
Of course, if a large number of A / D converters are used, the time can be shortened, but the circuit scale increases and the power consumption also increases, making it difficult to employ.
[0007]
The present invention has been made in view of the above problems, and an object thereof is to provide a minimum unit cell voltage detection circuit for an assembled battery capable of detecting a malfunction of a unit cell undervoltage at high speed with a simple circuit configuration. .
[0008]
[Means for Solving the Problems]
The voltage detection device for an assembled battery according to claim 1 of the present invention includes an analog multiplexer circuit (2) for sequentially selecting and outputting the voltages of the individual cells (11 to 15) of the assembled battery (1) , and the analog An analog minimum value detection circuit (3 ) that outputs a minimum value among the voltages of the individual cells (11 to 15) based on the voltages of the individual cells (11 to 15) sequentially output from the multiplexer circuit (2). ) and Bei example, said analog minimum value detection circuit (2), said plurality of switches (211-215) one of the cells has a which are individually connected to the terminals of each cell (11 to 15) A primary switch circuit (21) that selects and outputs a voltage, and a voltage input from the primary switch circuit (21) is a potential of one ( Z ) of a pair of output terminals ( Z , W ) of the other ( W ). Cut to a higher potential than the potential. Ete a pair of a secondary switch circuit for outputting the input end (22) of the analog minimum value detecting circuit (3), the analog minimum value detecting circuit (3) has a pair of said analog multiplexer circuit (2) One-way voltage follower circuit (303) that follows only one of the increasing direction and decreasing direction of one of the output terminals ( Z , W ) of the output terminal, and the output terminal of the one-way voltage follower circuit (303) Prior to the sequential selection operation of the analog multiplexer circuit (2) , the capacitor (302) connected between the pair of output terminals ( Z , W ) of the analog multiplexer circuit (2) and the other ( W ). And a charge switch (301) for charging the capacitor (302) to a voltage value equal to or higher than the maximum voltage of the unit cells (11 to 15) .
[0009]
According to this configuration, since the circuit configuration that discharges this capacitor to the voltage of this single cell is adopted only when the voltage of the single cell is smaller than the storage voltage of the capacitor that was initially charged, the accumulated voltage of the capacitor Can be made equal to the voltage of the unit cell having the minimum voltage after the comparison discharge with each unit cell voltage, and by reading out the residual accumulated voltage of this capacitor, the battery of the assembled battery can be obtained by only one A / D conversion. It is possible to know the terminal voltage of the unit cell that is most severe. Therefore, if the assembled battery is managed in accordance with the unit cell having the minimum voltage, the unit cell having the minimum voltage does not cause a problem.
[0010]
That is, according to the present invention, with a simple circuit configuration, it is possible to detect a malfunction of the cell voltage undervoltage at a high speed and manage the assembled battery (for example, restriction of input / output current) correspondingly.
[0012]
According to this configuration, since the potential of the analog minimum value detection circuit can be set regardless of the assembled battery, the circuit configuration can be simplified.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the voltage detection apparatus for an assembled battery of the present invention will be described in detail with reference to the following examples.
[0014]
[Example 1]
An embodiment of a voltage detection apparatus for a battery pack according to the present invention will be described with reference to a circuit diagram shown in FIG.
(Circuit configuration)
Reference numeral 1 denotes an assembled battery formed by connecting the cells 11 to 15 in series, but actually, a larger number of cells are connected in series.
[0015]
2 is an analog multiplexer circuit that sequentially selects and outputs each terminal voltage (hereinafter also referred to as a single cell voltage) of each unit cell (for example, 11 to 15) of the assembled battery 1, and 3 is each unit that the analog multiplexer circuit 2 sequentially outputs. A minimum value output circuit 4 detects and holds the minimum value of the battery voltage and selectively outputs it, and 4 is a controller for switching and controlling the analog multiplexer circuit 2. The output voltage Vout of the minimum value output circuit 3 is applied to the A / D converter 5 and A / D converted.
[0016]
The analog multiplexer circuit 2 includes a primary switch circuit 21 and a secondary switch circuit 22.
[0017]
The primary switch circuit 21 is composed of solid analog switches or relays 211 to 215 in which one of the main electrode pairs is individually connected to the positive electrodes of the unit cells 11 to 15, and selects only one unit cell voltage. Output. The other of the main electrode pairs of the odd-numbered switches 211, 213 and 215 is connected to the first input terminal X of the secondary switch circuit 22, and the other of the main electrode pairs of the even-numbered switches 212, 214 and 215 is the secondary switch. The second input terminal Y of the circuit 22 is connected.
[0018]
The secondary switch circuit 22 is composed of switches 221 to 224 composed of solid analog switches or relay contacts,
The direction of the voltage input between the input terminals X and Y is switched so that the output terminal Z has a higher potential than the output terminal W. The switch 221 connects the first input terminal X and the first output terminal Z, the switch 222 connects the first input terminal X and the second output terminal W, and the switch 223 connects the second input terminal Y and the first output terminal. The end Z is connected, and the switch 224 connects the second input end Y and the second output end W.
[0019]
The minimum value output circuit 3 includes a reset switch 31, a capacitor 32, an operational amplifier 33, a diode 34, a voltage follower circuit 35, and resistors 36 and 37. Of the unit cell voltage input between the output terminals Z and W, Output the minimum value. The operational amplifier 33 and the diode 34 constitute a one-way voltage follower circuit in which the output voltage follows only when the input voltage decreases. Reference numeral 305 denotes a normal bidirectional voltage follower circuit.
[0020]
The operational amplifiers 303 and 305 are supplied with a power supply voltage from a power supply voltage generation circuit (not shown), but the power supply voltage generated by the power supply voltage generation circuit is not grounded. The power supply voltage generation circuit applies a high power supply potential Vdd to the + input terminal of the operational amplifier 303 through the current limiting resistor 306, and further applies a high power supply potential Vdd to the high power terminal of the capacitor 302 through the switch 301 and the current limiting resistor 307. The lower power supply potential Vss is applied to the lower end L of the capacitor 302 from the power supply voltage generation circuit. That is, the + output terminal of this power supply voltage generating circuit generates a high power supply potential Vdd and the-output terminal generates a low power supply potential Vss. These high power supply potential Vdd and low power supply potential Vss are in relation to the ground potential or ground potential. The power supply voltage generating circuit is not a fixed potential but a floating potential. Eventually, this power supply voltage generating circuit is composed of a constant voltage circuit that generates a power supply voltage ΔV (= (Vdd−Vss)) between its pair of output terminals. ing.
[0021]
(Operation)
The operation of this assembled battery voltage detection circuit will be described below.
[0022]
First, the charge switch 301 is turned on, the capacitor 302 is charged through the current limiting resistor 307, and the charge switch 301 is turned off. The current limiting resistor 307 can be omitted. The charging voltage value of the capacitor 302 is set larger than the maximum single cell voltage of each single cell 11-15.
[0023]
Next, the voltage of the unit cell 11 is copied (held) to the capacitor 302. Specifically, only the switches 211, 212, 221, and 224 are turned on. As a result, the capacitor 302 is discharged, and the charging voltage of the capacitor 302 matches the voltage of the unit cell 11.
[0024]
Next, an attempt is made to copy (hold) the voltage of the unit cell 12 to the capacitor 302. Specifically, only the switches 212, 213, 222, and 223 are turned on. As a result, the capacitor 302 is additionally discharged only when the voltage of the unit cell 12 is lower than the voltage of the unit cell 11, and otherwise, the capacitor 302 holds the voltage of the unit cell 11.
[0025]
Thereafter, the voltage of each unit cell is applied to the minimum value output circuit 3, and eventually, the capacitor 302 is additionally discharged only when the unit cell voltage applied later is smaller than all the unit cell voltages up to that point.
[0026]
After all the unit cell voltages are sequentially input to the minimum value output circuit 3, the stored voltage of the capacitor 302 is A / D converted by an A / D converter (not shown) through a voltage follower circuit 305 and transmitted to a microcomputer (not shown). Is done.
[Brief description of the drawings]
[1] Ru circuit view showing an example of a minimum unit cell voltage detecting circuit of the assembled battery of the present invention.
[ Explanation of symbols]
1 assembled battery 2 analog multiplexer circuit 3 minimum value output circuit (analog minimum value detection circuit)
21 Primary switch circuit 22 Secondary switch circuit 303 Operational amplifier (one-way voltage follower circuit)
304 diode (one-way voltage follower circuit)
301 Charge switch 302 Capacitor C Temporary storage capacitor

Claims (1)

An analog multiplexer circuit (2) for sequentially selecting and outputting the voltages of the individual cells (11-15) of the assembled battery (1) ;
An analog minimum value detection circuit that outputs a minimum value of the voltages of the individual cells (11 to 15) based on the voltages of the individual cells (11 to 15) sequentially output from the analog multiplexer circuit (2). (3) and
Bei to give a,
The analog minimum value detection circuit (2)
A primary switch circuit (21) which has a plurality of switches (211 to 215) individually connected to terminals of each of the unit cells (11 to 15) and selects and outputs one unit cell voltage;
The voltage input from the primary switch circuit (21) is switched so that the potential of one ( Z ) of the pair of output terminals ( Z , W ) is higher than the potential of the other ( W ), and the analog minimum value A secondary switch circuit (22) for outputting to a pair of input terminals of the detection circuit (3);
Have
The analog minimum value detection circuit (3)
A one-way voltage follower circuit (303) that follows only one of the increasing direction and decreasing direction of the potential of one of the pair of output terminals ( Z , W ) of the analog multiplexer circuit (2) ;
A capacitor (302) connected between an output end of the one-way voltage follower circuit (303) and the other ( W ) of the pair of output ends ( Z , W ) of the analog multiplexer circuit (2) ;
A charge switch (301) for charging the capacitor (302) to a voltage value equal to or higher than the maximum voltage of the single cells (11-15) prior to the sequential selection operation of the analog multiplexer circuit (2) ;
Minimum unit cell voltage detecting circuits of the assembled battery, characterized in that it comprises a.

Images