JP3366841B2 - Battery voltage monitoring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery voltage monitoring device, and more particularly to a battery voltage monitoring device for measuring the voltage of each unit battery for a battery composed of a plurality of sets of unit batteries.

[0002]

2. Description of the Related Art A battery is constructed by connecting a plurality of unit cells in series according to the voltage of a load. Unit batteries generally have the same specifications, and since they are connected in series and the same current flows, they should have the same life and capacity, but factors such as differences in mounting conditions such as ambient temperature and manufacturing variations So, the actual state of the unit battery is slightly different. For this reason, only a specific unit battery may be overcharged or overdischarged, and it may be possible to charge the battery in the opposite polarity.

The battery voltage monitoring device measures the voltage of each unit battery to grasp the variation among the unit batteries, and
It monitors whether each battery is in a normal state,
Conventionally, there is a device provided with a voltage measuring circuit for measuring the potential for each unit battery.

[0004]

However, in the battery voltage monitoring device described above, unless a voltage measuring circuit having uniform characteristics is used, measurement variations occur between the voltage measuring circuits. Also, in recent years, electric vehicles that are becoming popular due to consideration for the environment require a very high voltage of 200 V to 400 V, and a battery pack having a low voltage of about 12 V and having a large capacity is connected in series to form an assembled battery. However, the battery module further includes cells of about 1.2 V, and if the cells are considered as a unit battery, the battery needs to be composed of an extremely large number of unit batteries. Therefore, in the above battery voltage monitoring device, the number of voltage measuring circuits becomes too large. Therefore, it is difficult to reduce the price.

It is conceivable to switch the single voltage measuring circuit 93 with the switch 92 to measure the potential of each unit battery 91 as shown in FIG. 20, but if the number of unit batteries is large, it is connected to the voltage measuring circuit. The configuration for switching the unit batteries and the control at the time of measurement become complicated, and it is difficult to reduce the price after all.

Therefore, an object of the present invention is to provide a low-cost battery voltage monitoring device having a simple structure.

[0007]

According to a first aspect of the present invention, a resistor array in which a plurality of resistors are connected in series and a connection point of unit cells and a connection point of resistors are connected in the same direction. And a plurality of diodes. The current changing means changes the current flowing through the resistor string so that the diodes become conductive in order from one diode, and the switch point detecting means detects the switch point between conduction and interruption in the diode, and the diode at the switch point and this By multiplying the resistance value of the resistor connected to the adjacent diode in the conducting state and the current value at the switch point, the voltage of the unit battery to which the adjacent diode and both poles are connected is calculated. To configure.

If adjacent diodes are conductive, a unit battery in which these diodes are connected to the positive electrode and the negative electrode is
The voltage is equal to the voltage drop across a resistor connected to the same diode. Further, since the diodes sequentially conduct from one diode, the current flowing through the diodes is 0 except for the diodes in the conductive state. Therefore, when one of the diodes next to each other is at the switch point and the other one is in the conducting state, the voltage drop across the resistors connected to both diodes next to each other is It is the product of the resistance of the vessel. Therefore, with a simple single voltage measurement circuit configuration that is configured so that the current flowing through the resistor string changes, the unit cells connected to the voltage measurement circuit do not have to be switched and the unit cells are independent of the number of unit cells. Is required.

The switch point detecting means is composed of a light receiving element for detecting light from the diode, which is composed of a light emitting diode as in the second aspect of the invention. Alternatively, as in the third aspect of the invention, a primary side winding is connected in series to the diode and a transformer for generating a detection signal in the secondary side winding is used. In both of these configurations, the switch point detection means is separated from the circuit including the battery, the resistor string, and the diode, and the influence of noise or the like is removed.

According to a fourth aspect of the present invention, the switch point detecting means is composed of voltage detecting means for substantially detecting a voltage drop in the resistor string, and the switch point has the voltage drop corresponding to the current. On the other hand, it is a point that changes discontinuously.

The slope of the voltage drop in the resistor string with respect to the current becomes the combined resistance value of the resistors connected to the diode in the cut-off state. Since the diodes sequentially conduct from one diode, the combined resistance value changes stepwise every time the diode passes through the switch point at which conduction and interruption of the diode are switched. Therefore, the voltage drop across the resistor string is discontinuous at the switch point. Therefore, the switch points of a plurality of diodes can be detected by a single voltage detecting means.

According to the fifth aspect of the invention, a current path is formed by connecting a resistor and a diode in series from the connection point of each unit battery. The diodes in the current path are aligned in the same direction, shorting the ends of the current path. The potential at the end point is changed by the voltage applying means so that the diodes are turned on or off sequentially from one of the diodes. A switch point detecting means detects a switch point at which conduction and interruption of the diode are switched. Then, from the potential of the end point at the switch point, the diode calculates the potential of the connection point of the unit battery to which the current path at the switch point is connected, and calculates the voltage of each unit battery based on the potential of each connection point. To do.

The diodes in the current path conduct sequentially from one diode, and when the diodes are at the switch point,
The potential at the end of the current path is equal to the potential at the connection point to which this current path is connected. The voltage of each unit battery can be obtained from the potential of each connection point. However, with a simple single voltage measuring circuit configuration, the voltage of the unit battery can be obtained without switching the unit batteries connected to the voltage measuring circuit and regardless of the number of unit batteries.

The switch point detecting means is composed of a light receiving element for detecting light from the diode, which is composed of a light emitting diode as in the invention described in claim 6. Alternatively, as in the invention described in claim 7, a primary side winding is connected in series to the diode and a transformer for generating a detection signal in the secondary side winding is used. In both of these configurations, the switch point detection means is separated from the circuit including the battery and the current path, and the influence of noise or the like is removed.

According to another aspect of the present invention, the switch point detecting means comprises current detecting means for detecting a current flowing through the voltage applying means, and the switch point is set so that the current is relative to the potential of the end point. It is a point that changes discontinuously.

The slope of the current flowing through the voltage applying means with respect to the applied voltage is a combined value of the conductances of the current paths in which the diode is in the conducting state. Since the diodes conduct in order from one diode, the combined conductance is
It changes stepwise each time it passes through the switch point at which conduction and interruption of the diode are switched. Therefore, the current flowing through the voltage applying means becomes discontinuous at the switch points. Therefore, the switch points of a plurality of diodes can be detected by a single current detecting means.

[0017]

DETAILED DESCRIPTION OF THE INVENTION

(First Embodiment) FIG. 1 shows a battery voltage monitoring apparatus of the present invention. The battery voltage monitoring device includes a plurality (five in the illustrated example) of unit batteries 11, 12, 13, 1 connected in series.
It is attached to the battery 1 consisting of 4, 15. Each of the unit batteries 11 to 15 may be a single cell or a plurality of cells. In the battery voltage monitoring device, a plurality of resistors (four in the illustrated example) 22, 23, 24, 25 are connected in series to form a resistor array 2. The resistance values of the resistors 22 to 25 are accurately measured in advance. Depending on the environment in which the device is installed, it is preferable that the device be temperature-compensated. At the end point 2b of the resistor array 2, a current adjusting circuit 4 serving as a current changing means.
Are connected so that the current I ₀₀ flowing through the resistor string 2 can be changed.

A plurality of diodes 31, 32, 33, 34, and 35 are connected in the same direction between the connection points 1a of the unit batteries 11 to 15 and the connection points 2a of the resistors 22 to 25. The positive electrode potential of the batteries 11 to 15 is connected to the positive electrode via the diodes 31 to 35 and the resistor 22 to.
It conducts at the potential V _k (k = 1 to 5) at the connection point 2a of 25. Diodes 31-35
Is composed of a light emitting diode and emits light when conducting.

The light receiving section 5 detects a switch point at which each of the diodes 31 to 35 switches between conduction and interruption, and is provided corresponding to each of the diodes 31 to 35. Each light receiving unit 5 includes a photodiode 51 which is a light receiving element that detects the light emitted from the diodes 31 to 35. The photodiode 51 may be connected to the diodes 31 to 35 by an optical fiber or the like, or may be an integrated photocoupler. Each of the light receiving sections 5 is configured such that when the corresponding diodes 31 to 35 are turned on, the photodiode 51 is turned on to output H level, and when shut off, outputs L level. That is, at the switch point where conduction and interruption are switched in each of the diodes 31 to 35, the output signal of the light receiving unit 5 is from H level to L level or from L level to H level.
Change to a level.

The output signal of the light receiving section 5 is input to the measurement control section 6.

The measurement control unit 6 is mainly composed of a computer and is constituted by an interface or the like, and is adapted to give a set value of the current I ₀₀ in the current adjusting circuit 4. FIG. 2 shows the details of the current adjusting circuit 4 and a part of the configuration of the measurement control unit 6. The current adjusting circuit 4 operates as a constant current source that keeps the current I ₀₀ at a set value, includes a transistor 41 and a comparator 43, and the output of the comparator 43 is input to the base of the transistor 41.

The collector of the transistor 41 is a resistor array 2
Is connected to the end point 2b. The emitter is grounded via the resistor 42, and the emitter voltage is fed back to the-input terminal of the comparator 43. A control voltage corresponding to the set value of the current from the measurement control unit 6 is input to the + input terminal of the comparator 43. The transistor 41 is opened and closed so that the emitter voltage becomes the control voltage, and the current I ₀₀ is maintained at the set value.

The measurement controller 6 comprises a counter 61 and a D / A converter 62. The counter 61 is reset when a reset signal is input by an external measurement start signal, and starts counting based on the clock signal.
The D / A converter 62 is configured to sequentially output a control voltage proportional to the count number of the counter 61 to the comparator 43. Therefore, the measurement control unit 6 can know the current I ₀₀ from the count number without providing a current sensor.

The measurement control unit 6 determines the voltage of the unit batteries 12 to 15 based on the switch points of the diodes 31 to 35 known from the output signal from the light receiving unit 5 and the current I ₀₀ known from the count number of the counter 61. Calculate

The operation of the above battery voltage monitor is shown in FIG.
This will be described with reference to FIGS. FIG. 3 shows the state of each part of the device. The resistance values of the resistors 22 to 25 are 500Ω and 66.
The values are 7Ω, 1 kΩ, and 2 kΩ, and the voltages of the unit batteries 11 to 15 are 10V. In the following description, the voltages of the unit batteries 11 to 15 will be referred to as E ₁ , E ₂ , E ₃ , E ₄ , and E.
₅ and the resistance values of the resistors 22 to 25 as R ₂ , R ₃ , R ₄ ,
R ₅ and the current value flowing through the diodes 31 to 35 are I ₁ ,
Let I ₂ , I ₃ , I ₄ , and I ₅ .

After resetting the counter, the current I ₀₀ flowing through the resistor string 2 changes in proportion to time as the number of counts increases.

First, when the current I ₀₀ is 0, the resistor 2
The potential V _k (k = 1 to 5) of each of the connection points 2a of 2 to 25 is the potential of the positive electrode of the unit battery 15 having the highest potential. Therefore, the connection point 1a of the remaining four unit batteries 11-14
Is the potential V _k (k = _k) of each connection point 2a of the resistors 22 to 25 whose potentials are connected by the diodes 31 to 34.
1 to 4). Therefore, the diodes 31 to 34
Is blocked, and I _k = 0 (k = 1 to 5).

When the current I ₀₀ begins to flow, the diode 35 becomes conductive, and the photodiode 5 of the light receiving portion 5 corresponding to this conducts.
1 conducts. The measurement control unit 6 receives the H level output signal. From this, it is known that it is operating normally.

When the current I ₀₀ begins to flow, each resistor 22-2
At 5, a voltage drop occurs. The voltage drop across resistor 25 is given by I ₀₀ R ₅ . Due to this voltage drop, the connection point potential V ₄ between the resistors 24 and 25 is lowered, and the unit battery 14
When it becomes equal to the positive electrode potential of, that is, when the voltage drop I ₀₀ R ₅ in the resistor 25 becomes equal to the voltage E ₅ of the unit battery 15, the diode 34 is switched from the cutoff state to the conduction state (switch point T ₄ ) and emits light.

By the light emission of the diode 34, the corresponding photodiode 51 of the light receiving portion 5 becomes conductive, and the output signal of the light receiving portion 5 is switched from the L level to the H level. From this, the measurement control unit 6 knows the switch point T ₄ . Then, the current I _{00 at the} switch point T ₄ is multiplied by the resistance value R ₅ of the resistor 25 to obtain the voltage E _{5 of the} unit battery 15.

When the diode 34 becomes conductive, the voltage drop in the resistor 25 is defined by the voltage E ₅ of the unit battery 15. Therefore, after the switch point T ₄ , even if the current I ₀₀ increases, the current flowing in the resistor 25, that is, The current I ₅ flowing through the diode 35 remains at the switch point T ₄ . The current I ₀₀ is increased by the current I ₄ supplied from the unit cell 14 via the diode 34.

Next, the voltage drop across the resistor 24 I ₀₀ R
_{When 4} increases and the connection point potential V ₃ of the resistors 23 and 24 becomes equal to the positive electrode potential of the unit battery 13, the diode 33 passes through the switch point T ₃ . Since the diode 34 becomes conductive and the connection point potential V ₄ between the resistors 24 and 25 is equal to the positive electrode potential of the unit battery 14, the resistor 2 is present at the switch point T ₃ .
The voltage drop I ₀₀ R _{4 at 4} is the voltage E _{4 of the} unit battery 14
Is equal to

The measurement control unit 6 knows from the output signal of the light receiving portion 5 corresponding switch points T ₃ and diode 33, the resistance value R ₄ of the current I ₀₀ and the resistor 24 at the switch point T ₃
The voltage E ₄ of the unit battery 14 is obtained by multiplying by.

When the diode 33 is turned on, the voltage drop in the resistor 24 is defined by the voltage E ₄ of the unit battery 14, so that even after the switch point T ₃ , the current flowing in the resistor 24 is switched even if the current I ₀₀ increases. It remains at the point T ₃ . Therefore, the current I ₄ flowing through the diode 34 becomes a saturation value thereafter. The current I ₀₀ is increased by the current I ₃ supplied from the unit battery 13 via the diode 33.

Hereinafter, the diodes 32 and 31 are turned on in this order, and the voltages I ₃ and E _{2 of the} batteries 13 and 12 are known from the current I _{00 at the} switch points T ₂ and T ₁ .

[0036] FIG. 4 shows the state of each part of the device when the voltage E ₄ of the unit batteries 14 drops from 10V to 8V,
The current I _{00 at} the switch point T ₃ of the diode 33 decreases as the voltage E ₄ of the unit battery 14 decreases from 10V to 8V. Then, the current I _{4 of the} diode 34
Has a smaller saturation value, and the current I _{3 of the} diode 33 has a larger saturation value.

By the way, when the voltage E ₄ of the unit battery 14 is further reduced, the saturation value of the current I ₄ of the diode 34 is further reduced, but the current I ₄ is a current flowing through the diode and is equal to or more than 0. Therefore, when the saturation value of the current I ₄ becomes 0 is the measurement limit of the voltage E ₄ of the unit battery 14. Based on this, the resistance values R _k (k = 2 to 5) of the resistors 22 to 25 are set according to the measurement range to be measured. When the diodes 32 to 34 are saturated, the current I
_The condition that _k (k = 2 to 4) flows is as follows. I _k = (E _k / R _k ) − (E _{k + 1} / R _{k + 1} ) ≧ 0 (1)

The resistance value R of the resistor is set so as to satisfy this condition.
You can set _k . For example, since the unit batteries are usually batteries having the same specifications, the formula (1) can be expressed by the formula (2) when the measurement range of E _k (k = 2 to 5) is E ± ΔE. I _k = ((E−ΔE) / R _k ) − ((E + ΔE) / R _{k + 1} ) ≧ 0 (2) Therefore, if α = ΔE / E, then R _{k + 1} / R _k ≧ (1 + α ) / (1−α) (3) For example, when trying to obtain a measurement range of about ± 10%, if the resistance values R _k and R _{k + 1 of} adjacent resistors are set to differ by about 25%. Good.

In the present embodiment, the current I ₀₀ is set to increase with time, but conversely, the set value of the current I ₀₀ of the voltage adjusting circuit 4 may be given so as to decrease linearly from the maximum current. . Further, the light receiving unit 5 corresponding to the diode 35 may be omitted if it is not necessary to confirm that the device is operating normally.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention. It is configured such that conduction and interruption of the diode are detected by different configurations, and in the figure, parts that operate in the same manner as in the first embodiment are denoted by the same reference numerals, and differences from the first embodiment are mainly focused. explain.

Diodes 31A, 32A, 33A, 34
A and 35A are not light emitting diodes but ordinary diodes. The configuration is such that the conduction and interruption of the diodes 31A to 35A are known by the pulse transformer 52 which is the switch point detection means, the comparator 53 and the like. Pulse transformer 52
Are diodes 31A to 35A and resistors 22 to 25, respectively.
A primary winding 52a is connected in series between the connection points 2a of the above. The secondary windings 52b of the pulse transformer 52 are connected in series with each other, and when any of the diodes 31A to 35A becomes conductive, the detection signal thereof is input to the + input terminal of the comparator 53. A constant voltage, which is the threshold value of the detection signal, is input to the-input terminal of the comparator 53, and the conduction and interruption of the diodes 31A to 35A are input to the measurement control unit 6A as a binary signal. There is.

The conduction and interruption of the diode in this embodiment are detected as follows. Diodes 31A to 35
When any one of A becomes conductive and a ramp-shaped current i flows through it ((A) of FIG. 6), an induced voltage v ₁ is generated across the primary winding 52a of the pulse transformer 52. In general, there is a relationship between the induced voltage v ₁ and the current I as expressed by equation (4), where L is an inductance. v ₁ = -L (di / dt) (4)

Therefore, the voltage v ₁ of the primary winding 52a has a rectangular waveform ((B) of FIG. 6), and the secondary winding 52a
The voltage v ₂ of b has a pulse-like waveform ((C) of FIG. 6). The time when this pulse waveform is detected is the switch point at which conduction and interruption are switched in each of the diodes 31A to 35A.

When any of the diodes 31A to 35A switches between conduction and interruption, the comparator 53 outputs an H level output signal to the measurement control unit 6A. The current I ₀₀ increases proportionally with time and the diode 35
Since the currents A, 34A, 33A, ... Conduct in this order, it is possible to know which diode the switch point is by knowing which switch point.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. It is configured such that conduction and interruption of the diode are detected by different configurations, and in the figure, parts that operate in the same manner as in the first embodiment are denoted by the same reference numerals, and differences from the first embodiment are mainly focused. explain.

A voltage measuring circuit 5B serving as a voltage detecting means is provided in parallel with the current adjusting circuit 4 at the end point 2b of the resistor array 2. The potential of the end point 2b of the resistor array 2, that is, the potential V ₁ is
The voltage drop across the resistor string 2 is subtracted from the total voltage of the unit batteries 11 to 15. By measuring the potential V ₁ , a change in the voltage drop across the resistor string 2 can be substantially detected.

The operation of the battery voltage monitoring device will be described. In the present embodiment, the battery 1, the resistor array 2, the diodes 31A to 35A, and the current adjusting circuit 4 have substantially the same configuration, so the respective parts of the device when the current I ₀₀ changes can be described with reference to FIG.

As described in the first embodiment, etc., the current I ₀₀
As the current increases, the diode 35A is sequentially turned on. In this process, for example, assuming that the diodes 34A and 35A are conductive and the diodes 31A, 32A and 33A are cut off, the resistor 25 connected to the diodes 34A and 35A has a constant voltage drop and the diodes 31A,
The voltage drop of the resistors 22, 23, 24 connected to 32A, 33A increases in proportion to the current I ₀₀ . Therefore, the slope of the voltage drop in the resistor array 2 with respect to the current I ₀₀ is the combined resistance value (R ₂ + R ₃ + R) of the resistors 22, 23 and 24.
₄ )

Then, the switch point T _{3 of the} diode 33A
After passing, the voltage drop of the resistor 24 in addition to the resistor 25 becomes constant. Therefore, the slope of the voltage drop of the resistor string 2 with respect to the current I ₀₀ is the combined resistance value (R ₂ + R ₃ ) of the resistors 22 and 23.

Thus, the voltage drop current I of the resistor string 2
_The slope with respect to ₀₀ gradually decreases after passing the switch point. Since the current I ₀₀ is proportional to time, the potential V ₁ draws a straight line having different slopes before and after the switch point with respect to time.

The measurement control unit 6B calculates a point where the change of the potential V ₁ with time becomes discontinuous, that is, an inflection point, and sets the first discontinuous point as the switch point T ₄ in the diode 14, and the discontinuous points appearing one after another. Diode 13 and diode 1
2 ... Switch points T ₃ , T ₂ , ...
The current I ₀₀ and the resistance value R _k (K = 2 at the switch point)
5), the voltage of each unit battery 12-15 is calculated.

Since the switching characteristics of the diodes 31A to 35A are not completely rectangular, depending on the required measurement accuracy, the data D of the potential V ₁ as shown in FIG.
The regression line L may be obtained from the intersection point P to be the inflection point.

(Fourth Embodiment) FIG. 9 shows a fourth embodiment of the present invention. In each of the above-described embodiments, the voltage E ₁ of the unit battery 11 that has the lowest potential can be measured. In the figure, parts that operate in the same manner as in the first embodiment will be assigned the same reference numerals, and the description will focus on the differences from the first embodiment. In the resistor array 2A, in addition to the resistors 22 to 25, the resistor 21 is connected between the resistor 22 and the current adjusting circuit 4.

A diode 30A is connected between the end point 2b of the resistor array 2A and the negative electrode of the unit battery 11 in the same direction as the other diodes 31A to 35A.

The current adjusting circuit 4 is connected to the power supply 7.
The power supply 7 is a power supply that outputs a negative voltage, and enables the potential at the end point 2b of the resistor array 2A to be a negative voltage. As a result, in the measurement control unit 6C, the unit battery 11 is calculated by multiplying the current value I ₀₀ when the conduction and interruption of the diode 30A are switched (switch point) by the resistance value R ₁ of the resistor 21. Although the configuration for detecting conduction and interruption in the diodes 31A to 35A is omitted in the figure, the configurations of the above-described embodiments and the like can be applied.

(Fifth Embodiment) FIG. 10 shows a fifth embodiment of the present invention. In each of the above embodiments, the current adjustment circuit 4
Is configured as a constant current power supply type that keeps the current I ₀₀ at a set current and the current I ₀₀ is known from the count number of the counter of the measurement control unit. Instead, the potential of the end point 2b of the resistor array 2 is This is another current adjusting circuit 4A configured as a constant voltage power source type that maintains a set voltage. In the figure, parts that operate in the same manner as in the first embodiment will be assigned the same reference numerals, and the description will focus on the differences from the first embodiment.

The current adjusting circuit 4A is the end point 2b of the resistor array 2.
The potential V ₁ (E ₀₀ ) at is changed from 0 at a constant change speed.

A current measuring circuit 8 is provided in series with the resistor array 2 and the current adjusting circuit 4A, and measures the current I flowing through the resistor array 2. The detection signal of the current measuring circuit 8 is input to the measurement control unit 6D. Diode 3
Although the configuration for detecting conduction and interruption in 1A to 35A is omitted, the configurations of the first and second embodiments can be applied.

FIG. 11 shows the state of each part of the apparatus.
The voltage E at the end point 2b of the armature array 2 ₀₀(V in the figure₁ ) Is
After the counter is reset, the number of counts increases
Change proportionally with time.

At first, when the potential E ₀₀ is 0, the maximum current of the resistor string 2 is flowing, and the diodes 31A to 35A.
Are all conducting. Therefore, each resistor 22-25
The voltage drop of each resistor 22-25 is diode 31A
It is equal to the voltage of each unit battery 12-15 connected by ~ 35A.

When the potential E ₀₀ rises and becomes higher than the potential of the positive electrode of the unit battery 11, the diode 31A shuts off. Switch point T at which diode 31A switches from conduction to cutoff
_{At 1} , the current I detected in the current measuring circuit 8 matches the current flowing through the resistor 22. Therefore, the voltage drop of the resistor 22 becomes IR ₂ . The measurement control unit 6D applies the resistance value R of the resistor 22 to the current I at the switch point T ₁ .
Obtaining a voltage E ₂ of the unit batteries 12 multiplied by _2.

The potential E ₀₀ further rises, and the diode 32
At the switch point T _{2 at} which A switches from conduction to cutoff, the current I detected by the current measuring circuit 8 matches the current flowing through the resistor 23. Therefore, the voltage drop of the resistor 23 becomes IR ₃ . The measurement control unit 6D obtains the voltage E ₃ of the unit battery 13 by multiplying the current I at the switch point T ₂ by the resistance value R ₃ of the resistor 23. After that, as the potential E ₀₀ rises, the voltages of the unit batteries 14 and 15 are sequentially obtained from the current I at the switch points T ₃ and T ₄ .

Also in this embodiment, by adopting the configuration of the resistor array 2A and the diodes 30A to 35A in the fourth embodiment (FIG. 9) and using the current adjusting circuit 4B as a power source capable of outputting a negative voltage, a unit battery can be obtained. The voltage of 11 can be measured together.

In each of the above embodiments, the unit battery 15
The diodes 35 and 35A connected to the positive electrode of 2 can be omitted because they conduct when the current flows through the resistor rows 2 and 2A. However, since the measured value of the voltage of the unit battery 15 has an error corresponding to the forward voltage of the diode, it is preferable that the measured value depends on the required measurement accuracy.

(Sixth Embodiment) FIG. 12 shows a sixth embodiment of the present invention. In the drawings, the parts denoted by the same reference numerals as those in the above-mentioned drawings operate substantially in the same manner, and therefore the differences from the above-described embodiments will be mainly described. The battery voltage monitoring device includes six unit batteries 11, 12, 13, 1 that constitute the battery 1.
Current paths 71, 72, from each connection point 1a of 4, 15, 16
73, 74, 75, 76 are formed. Current paths 71 to
Reference numeral 76 denotes a resistor 701 and a diode 702 connected in series. The anode of the diode 702 is the unit cell 1
They are arranged so that they are on the side of 1 to 16. Current paths 71-76
7a is short-circuited, and the power supply unit 8 serving as voltage applying means is connected.

FIG. 13 shows the details of the power supply unit 8 and includes a transistor 81 for varying the voltage. The transistor 81 has a collector connected to a constant voltage power source (voltage V ′) (not shown) via a collector resistor 82, and an emitter grounded via an emitter resistor 83. Output voltage V from the connection point of collector resistor 82 and collector of transistor 81
_out is taken _out and applied to the end point 7a of the current paths 71 to 76. The potential of the end point 7a (hereinafter referred to as the output potential) is given by the output voltage V _out . The transistor 81 performs voltage amplification operation with respect to the input voltage of the base at a ratio of the collector resistance 82 and the emitter resistance 83, and the output voltage is linearly applied to the input voltage V _{B of the} base as shown in FIG. It is designed to be used.

The command value of the output voltage given as a digital signal from the microcomputer 84 is converted into an analog signal by the D / A converter 85 and input to the base of the transistor 81, and the output voltage is converted into the command value. The voltage is controlled accordingly. The control range of the output voltage is such that the lower limit is 0 and the upper limit covers the voltage of the battery 1. The lower limit may be a size that covers the lowest voltage of the unit battery if it is known in advance.

The diode 702 is a light emitting diode which constitutes the photocoupler 5C together with the phototransistor 53 which is a light receiving element.
3 is turned on. When the variable output potential becomes lower than the potential on the positive electrode side of the unit batteries 11 to 16, the diode 702 of the current paths 71 to 76 formed from the connection point 1a on the positive electrode side of the unit batteries 11 to 16 becomes conductive and the resistor is turned on. A current corresponding to the resistance value of 701 flows. Photo coupler 5
C detects a switch point at which each diode 702 switches between conduction and interruption and detects detection signals SIG1, SIG2, SIG
3, SIG4, SIG5, SIG6 are output.

The detection signals SIG1 to SIG6 are turned on to the ground potential (L level) by turning on the phototransistor 53 when the diode 702 is conductive, and pulled up to the potential _Vcc and turned to H level when cut off. Detection signal SIG1
The switch point of the diode 702 is when SIG6 switches from the L level to the H level or from the H level to the L level. Instead of the photocoupler 5C, the diode and the light receiving element may be separately provided as in the first embodiment.

Detection signal SIG of the photocoupler 5C for detecting conduction and interruption of the diode 702 in the current paths 71 to 76.
1 to SIG6 are input to the microcomputer 84 of the power supply unit 8. The microcomputer 84 triggers the rise of each of the detection signals SIG1 to SIG6 to specify the switch point.

The operation of the above battery voltage monitoring apparatus is shown in FIG.
2, FIG. 13, FIG. 14, and FIG. FIG. 15 shows the state of each part of the apparatus. In the following description, the voltage of the unit batteries 11 to 16 is simply E. Therefore, the potential on the positive electrode side of the unit batteries 11 to 16 is
1 to E, 2E, 3E, 4E, 5E, 6E.

The voltage command value from the microcomputer 84 is increased in proportion to the time (t), and the output potential of the end points 7a of the current paths 71 to 76 is continuously and linearly increased from 0 to over 6E. When going (line L _a of FIG. 15), the potential of the positive electrode side of all first unit cells 11 to 16, greater than the output potential, but all current paths 71-76 is conducting, the output voltage As the voltage rises, the current path 7 connected to the lower unit battery 11 in FIG.
It is cut off in order from 1, and the detection signal SIG1 of the photocoupler 5C corresponding to the current path 71 is sequentially changed from L to H (FIG. 15). The microcomputer 84 outputs the output voltage values V, 2V, 3V, 4 from the voltage command value at the switch point.
V, 5V and 6V are specified (FIG. 15).

At the switch point, the output potential is equal to the potential of the connection point 1a of the unit batteries 11-16. For example, the current path 7 formed from the connection point 1a on the positive electrode side of the unit battery 11
The output potential when the diode 702 of No. 1 is at the switch point is the potential E of the positive electrode of the unit battery 11. The output potential is given by the output voltage (V _out ) of the power supply unit 8, and the output voltage at the switch point is specified as described above. Therefore, the positive electrode potentials 2E, 3E, ... known. And the potentials E and 2 of the batteries 11 to 16 which are adjacent to each other
A voltage measurement value (E in this case) of each of the unit batteries 11 to 16 is obtained from the difference of E, 3E, ....

The conduction and interruption of the diode 702 may be detected by the pulse transformer as in the second embodiment.

The current paths 71 to 76 are connected so that the diode 702 is on the side of the power supply unit 8 and the resistor 701 is on the side of the unit batteries 11 to 16, but it may be reversed. Further, the diodes 702 may be arranged such that the anodes are arranged on the unit batteries 11 to 16 side instead of the anodes are arranged on the unit batteries 11 to 16 side. In this case, when the output voltage is increased from 0 as described above, first, all the current paths 71 to 76 are initially generated.
Is cut off, and as the output voltage increases, the unit batteries 11 sequentially switch from cutoff to conduction. Even with such a configuration, the unit battery 1 at the switch point of the diode 702
The positive electrode potentials 1 to 16 are obtained.

(Seventh Embodiment) FIG. 16 shows a seventh embodiment of the present invention. The configuration is such that conduction and interruption of the diode in the current path are detected by different configurations, and in the figure, parts that operate in the same way as in the sixth embodiment are assigned the same numbers and differences from the sixth embodiment. I will explain mainly.

The diode 703 of the current paths 71 to 76 is composed of a normal diode.

FIG. 17 shows the details of the power supply section 8A.
It has basically the same configuration as the power supply unit 8 in FIG. The microcomputer 84 receives the voltage value across the emitter resistor 83 via the A / D converter 86. The microcomputer 84, the A / D converter 86, and the emitter resistor 83 constitute a current detecting means, and the microcomputer 84 causes the current I flowing through the power supply unit 8A.
Is obtained by dividing the above-mentioned voltage value taken in by the resistance value of the emitter resistor 83.

The operation of the above battery voltage monitoring apparatus is shown in FIG.
6, FIG. 17, and FIG. FIG. 18 shows the state of each part of the apparatus.

The potential of the end points 7a of the current paths 71 to 76 rises in proportion to the time t, as in the sixth embodiment, and the power source section 8
The current I flowing through A is obtained at, for example, predetermined intervals. When the output potential is smaller than the potential on the positive electrode side of the unit battery 11, the current I flowing in the power supply unit 8A is the sum of the currents flowing in all the current paths 71 to 76, and at this time, the slope with respect to the output potential, that is, the output voltage V _out . Each current path 7
1 is a sum of conductances 1 to 76 depending on the resistance value of the resistor 701.

When the output potential further rises and passes through the switch point of the diode 703 of the current path 71 formed from the connection point 1a on the positive electrode side of the unit battery 11, the diode 703 of the current path 71 is cut off and the power source is turned off. The current I flowing through the portion 8A is the sum of the currents flowing through the current paths 72 to 76 excluding the current path 71. Therefore, the slope of the current I with respect to the output voltage becomes smaller by the conductance of the current path 71 with the switch point of the diode 703 of the current path 71 as a boundary.

Therefore, the switch point of the diode 703 of the current path 71 is obtained from the bending point at which the slope of the current I flowing in the power supply section 8A with respect to the output voltage V _out changes discontinuously. In this way, the switch points of the diodes 702 of all the current paths 71 to 76 are known from the inflection points that appear one after another. FIG. 19 shows the detected value of the current I as the output voltage V _out.
Is plotted against the inflection point, for example, the current I
The regression lines L1 and L2 having different slopes of the detected values of
Obtain from the intersection P.

As in the sixth embodiment, from the output voltages V, 2V, ... At the switch point, the potentials E, 2E on the positive side of the unit battery to which the current path of the diode 702 at the switch point is connected. , Are known, and the voltage value of the unit battery (here, E) is obtained.

Although each of the above embodiments is applied to the battery 1 that outputs a positive voltage with respect to the ground potential, it can also be applied to a device that outputs a negative voltage.

In the case where the light receiving element is used to switch between conduction and interruption of the diode as in the first and sixth embodiments, the structure is not limited to that of each of the above embodiments, and light is emitted in series or in parallel with an ordinary diode. A configuration in which a diode is connected or a configuration in which a non-polar light emitting element is connected in series with a normal diode may be used. Further, the detection of switching between conduction and interruption in the diode is not limited to the configurations of the above-described first to seventh embodiments, and it is arbitrary as long as conduction and interruption can be detected.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first battery voltage monitoring device of the present invention.

FIG. 2 is a circuit diagram of a main part of a first battery voltage monitoring device of the present invention.

FIG. 3 is a first graph illustrating the operation of the first battery voltage monitoring device of the present invention.

FIG. 4 is a second graph explaining the operation of the first battery voltage monitoring device of the present invention.

FIG. 5 is a circuit diagram of a second battery voltage monitoring device of the present invention.

FIG. 6 is a time chart explaining the operation of the second battery voltage monitoring device of the present invention.

FIG. 7 is a circuit diagram of a third battery voltage monitoring device of the present invention.

FIG. 8 is a graph illustrating the operation of the third battery voltage monitoring device of the present invention.

FIG. 9 is a circuit diagram of a fourth battery voltage monitoring device of the present invention.

FIG. 10 is a circuit diagram of a fifth battery voltage monitoring device of the present invention.

FIG. 11 is a graph illustrating the operation of the fifth battery voltage monitoring device of the present invention.

FIG. 12 is a circuit diagram of a sixth battery voltage monitoring device of the present invention.

FIG. 13 is a circuit diagram of a main part of a sixth battery voltage monitoring device of the present invention.

FIG. 14 is a first graph illustrating the operation of the sixth battery voltage monitoring device of the present invention.

FIG. 15 is a second graph illustrating the operation of the sixth battery voltage monitoring device of the present invention.

FIG. 16 is a circuit diagram of a seventh battery voltage monitoring device of the present invention.

FIG. 17 is a circuit diagram of essential parts of a seventh battery voltage monitoring device according to the present invention.

FIG. 18 is a first graph illustrating the operation of the seventh battery voltage monitoring device of the present invention.

FIG. 19 is a second graph explaining the operation of the seventh battery voltage monitoring device of the present invention.

FIG. 20 is a circuit diagram showing an example of a conventional battery voltage monitoring device.

[Explanation of symbols]

1 Battery 11, 12, 13, 14, 15, 16 Unit Battery 2, 2A Resistor Row 21, 22, 23, 24, 25 Resistor 31, 32, 33, 34, 35, 30A, 31A, 32
A, 33A, 34A, 35A Diodes 4, 4A Current adjusting circuit (current changing means) 51 Photodiode (switch point detecting means) 52 Pulse transformer (switch point detecting means) 52a Primary side winding 52b Secondary side winding 5B Voltage Measurement circuit (voltage detection means) 53 Phototransistor (switch point detection means) 6,6A, 6B, 6C, 6D Measurement control units 71, 72, 73, 74, 75, 76 Current path 7a End point 701 Resistor 702, 703 Diode 8, 8A Power supply section (voltage applying means) 83 Emitter resistance (current detecting means) 84 Microcomputer (current detecting means) 86 A / D converter (current detecting means)

Front page continued (72) Inventor Naoki Ishii 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Prefecture Japan Auto Parts Research Institute, Inc. (72) Inventor Kunio Kanamaru 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. ( 72) Inventor Yasuhiro Otsuka 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Fumihiko Asakawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Company, Ltd. (72) Inventor, Susumu Ukita Aichi Prefecture 1 Toyota-cho, Toyota-shi Toyota Motor Corporation (56) Reference JP-A-6-78403 (JP, A) JP-A-5-258778 (JP, A) JP-A-9-15311 (JP, A) JP-A-9-139237 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/42-10/48 G01R 19/165 G01R 31/36 H02J 7/00-7 / 12

Claims (8)

(57) [Claims] 1. A battery voltage monitoring device for measuring the voltage of each unit cell of a battery composed of a plurality of sets of unit cells connected in series, wherein a resistor string in which a plurality of resistors are connected in series and a unit A plurality of diodes connected in the same direction between the connection point of the battery and the connection point of the resistor, and connected to the end points of the resistor row to change the current flowing through the resistor row to make the diodes sequentially connected from one diode or A current changing means for sequentially shutting off and a switch point detecting means for detecting a switch point at which conduction and interruption of the diode are switched are provided, and are connected to the diode at the switch point and the diode in the conductive state adjacent to the diode. Multiplying the resistance value of the resistor and the current value at the switch point,
A battery voltage monitoring device characterized in that it calculates the voltage of a unit battery in which both diodes and both electrodes adjacent to each other are connected. 2. The battery voltage monitoring device according to claim 1, wherein the diode is a light emitting diode, and the switch point detecting means is a light receiving element for detecting light emitted from the light emitting diode. A battery voltage monitoring device that detects a voltage based on a detection signal of a light receiving element. 3. The battery voltage monitoring device according to claim 1, wherein the switch point detecting means is a transformer in which a primary winding is connected in series to the diode, and the switch point is a secondary winding. Voltage monitoring device that detects the output signal of the battery. 4. The battery voltage monitoring device according to claim 1, wherein the switch point detecting means is constituted by voltage detecting means that substantially detects a voltage drop in the resistor string, and the switch point is the voltage. A battery voltage monitoring device in which the drop changes discontinuously with respect to the current. 5. A battery voltage monitoring device for measuring the voltage of each unit cell of a battery composed of a plurality of sets of unit cells connected in series, wherein:
It consists of connecting a resistor and a diode in series,
Voltage applying means for forming a current path in which the diodes are aligned in the same direction and having short-circuited end points, and changing the electric potential of the end points to turn on or turn off the diodes in order from one diode, and conduction of the diodes. Provided with a switch point detection means for detecting a switch point at which the cutoff is switched, the potential at the connection point of the battery to which the current path at the switch point is connected is obtained from the potential at the above-mentioned end point at the switch point, and the potential at each connection point A battery voltage monitoring device characterized in that the voltage of each battery is calculated based on the above. 6. The battery voltage monitoring device according to claim 5, wherein the diode is a light emitting diode, and the switch point detecting means is a light receiving element for detecting light emitted from the light emitting diode. A battery voltage monitoring device that detects a voltage based on a detection signal of a light receiving element. 7. The battery voltage monitoring device according to claim 5, wherein the switch point detecting means is composed of a transformer in which a primary winding is connected in series to the diode, and the switch point is a secondary winding. Voltage monitoring device that detects the output signal of the battery. 8. The battery voltage monitoring device according to claim 5, wherein the switch point detecting means is constituted by current detecting means for detecting a current flowing through the voltage applying means, and the switch point is the end point where the current is the end point. The battery voltage monitoring device that has a point that changes discontinuously with respect to the potential of the battery.