JP2014081268A - Battery system, and electrically driven vehicle and power storage device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a voltages of a battery in a short time and to detect a battery voltage by a simple calculation.SOLUTION: A battery system comprises: a battery pack 1 having a plurality of batteries 2 connected in series; a voltage detector 3 for detecting a voltage of the battery 2; and a voltage detection switch 4 for connecting the battery 2 with the voltage detector 3. The voltage detector 3 includes: a voltage detection circuit 5 for detecting the voltage of the battery 2 with a predetermined period (Δt) having a capacitor 8 connected with at an input side of the detector; a voltage detection line 10 including a series resistance 6 connected with the battery 2 through the voltage detection switch 4; and a calculation circuit 7 for calculating the voltage of the battery 2. In the battery system, the voltage detection switches 4 are switched to input the voltage of the battery 2 into the voltage detection circuit 5 so that the battery voltage is detected. The calculation circuit 7 calculates a convergent voltage (V) which detected voltages converge to based on detection voltages detected at least three times with the predetermined period (Δt) through the voltage detection circuit 5. The voltage of the battery 2 is detected from the convergent voltage (V).

Description

  The present invention relates to a battery system including a voltage detection circuit that detects the voltage of each battery constituting an assembled battery, an electric vehicle including the battery system, and a power storage device.

  A battery system in which a plurality of batteries are connected in series to increase the output voltage is used for applications such as supplying electric power to the motor of an electric vehicle. However, monitoring the battery voltage ensures safety. Is important above. If the battery voltage is out of the normal usable range, the battery may be overcharged or overdischarged and stable operation may not be ensured. Because there is. In addition, it is necessary to avoid erroneous detection of voltage due to noise from devices such as inverters, motors, and converters connected to the battery system and from the outside. This is because accurate measurement of the battery voltage is important as described above. Further, the measured battery voltage is also used for detecting the remaining capacity and used for safety control of the battery system. Moreover, since it is also fed back to the control of the battery system and devices connected thereto, which also affects the system behavior, it is required to detect the battery voltage promptly. Also, in the safety monitoring of the battery system, the detection that the battery voltage has become abnormal is an immediate operation, for example, an operation that ensures safety, such as switching the relay connected to the output side open. It is extremely important to take For these reasons, the battery system is required to quickly detect the voltage of the battery without the influence of noise.

  As a conventional technique for accurately detecting the voltage of a battery, a low-pass filter is used to reduce the influence of noise. The low-pass filter is composed of a series resistor of the voltage detection line and a capacitor connected to the input side. The smaller the constants, the higher the cutoff frequency, and the larger the constant, the lower the cutoff frequency. The battery voltage of the battery system is DC, and the noise component from the inverter and converter should be cut to detect the battery voltage, so the low-pass filter has a lower cutoff frequency and the noise component is more effective. It is recommended to remove it. However, in order to lower the cutoff frequency of the low-pass filter, it is necessary to increase either or both of the resistance value of the series resistor and the capacitance of the capacitor. On the other hand, when the resistance value of the series resistor and the capacitance of the capacitor are increased, the time constant between the series resistor and the capacitor constituting the low-pass filter increases, and it takes time to charge the capacitor after switching the voltage detection switch. As a result, it takes a long time for the voltage across the capacitor to rise to the saturation voltage. Since it takes more than seven times the time constant until the voltage across the capacitor reaches 99.9% or more of the saturation voltage, there is a problem that the low-pass filter lengthens the detection time. In order to avoid this harmful effect, that is, to shorten the time until the voltage of the capacitor reaches the saturation voltage and speed up the detection time, the resistance value of the series resistance of the low-pass filter and the capacitance of the capacitor are reduced. A problem arises that the cutoff frequency increases and is susceptible to noise.

  In order to solve the above problems, the capacitor voltage of the low-pass filter, that is, the input voltage of the voltage detection circuit is detected at the first charging time and the second charging time, and the saturation voltage is exponentially determined from the detected voltage. A battery system for computing the above has been developed. (See Patent Document 1)

JP 2003-197273 A

  The battery system of Patent Document 1 calculates the saturation voltage by calculating the exponential function, so that the battery voltage can be detected quickly. However, since the calculation is performed with a complicated calculation formula, the calculation circuit is simple, easy, and inexpensive. Therefore, it is difficult to quickly detect the battery voltage.

  The present invention has been developed for the purpose of solving this drawback. An important object of the present invention is to provide a battery system capable of detecting the voltage of a battery by extremely simple calculation while accurately detecting the voltage of the battery in a short time, an electric vehicle including the battery system, and a power storage device. is there.

Means for Solving the Problems and Effects of the Invention

  The battery system of the present invention includes an assembled battery 1 formed by connecting a plurality of batteries 2 in series, a voltage detector 3 for detecting the voltage of the battery 2, and the battery 2 of the assembled battery 1 on the input side of the voltage detector 3. And a voltage detection switch 4 connected to. The voltage detector 3 has a capacitor 8 connected to the input side, a voltage detection circuit 5 that detects the voltage of the battery 2 at a predetermined period (Δt), and a series resistor 6 that is connected to the battery 2 via the voltage detection switch 4. And a calculation circuit 7 for calculating the voltage of the battery 2 detected by the voltage detection circuit 5. In this battery system, the voltage detection switch 4 is switched in order, the voltage of the battery 2 is input to the input side of the voltage detection circuit 5, and the voltage of the battery 2 is detected by the voltage detection circuit 5. Further, the arithmetic circuit 7 of the battery system described above calculates a convergence voltage (V) at which the detection voltage converges from at least three detection voltages detected at a predetermined cycle (Δt) by the voltage detection circuit 5 as follows: The voltage of the battery 2 is detected from the convergence voltage (V).

ただし、この式において、
Ｙ1は、時間（ｔ）における検出電圧Ｖ(t)、
Ｙ2は、時間（ｔ＋Δｔ）における検出電圧Ｖ(t+Δt)、
Ｙ3は、時間（ｔ＋２Δｔ）における検出電圧Ｖ(t+2Δt)である。

However, in this formula:
Y1 is the detected voltage V (t) at time (t),
Y2 is the detected voltage V (t + Δt) at time (t + Δt),
Y3 is the detected voltage V (t + 2Δt) at time (t + 2Δt).

  The battery system described above has a feature that the voltage of the battery can be accurately detected in a short time by an extremely simple calculation. This is because the battery system described above calculates the convergence voltage by a simple calculation from the three detection voltages, regardless of the calculation formula of the complex exponential function as in the prior art.

  The battery system of the present invention can detect the voltage of the battery 2 by connecting the input terminal of the voltage detection circuit 5 to the positive and negative electrodes of the battery 2 via the pair of voltage detection switches 4 and the voltage detection line 10. it can.

  In the above battery system, the voltage of each battery can be accurately detected in a very short time after switching the pair of voltage detection switches and connecting the positive and negative electrodes of each battery to the voltage detection circuit. There is a feature that can accurately detect the voltage of a plurality of batteries in a short time.

In the battery system of the present invention, a discharge circuit 11 for discharging the capacitor 8 is connected to the input side of the voltage detection circuit 5 when the voltage detection switch 4 is in an off state, and the capacitor 8 is discharged by this discharge circuit 11. Can be detected.
In this battery system, the capacitor is discharged in the OFF state of the voltage detection switch to detect the voltage of the battery, so that the voltage can be detected with higher accuracy.

In the battery system of the present invention, the input resistor 14 is connected to the input side of the voltage detection circuit 5, and the voltage of the battery 2 can be divided by the input resistor 14 and the series resistor 6 and input to the voltage detection circuit 5. .
In this battery system, since the voltage of the battery can be stepped down to the optimum voltage for the voltage detection circuit to detect by using the series resistance and the input resistance, for example, a high withstand voltage element or the like is used for the voltage detection circuit. Therefore, the component cost can be reduced.

  The electric vehicle according to the present invention includes a battery system 100. The battery system 100 includes a battery pack 1 formed by connecting a plurality of batteries 2 in series, a voltage detector 3 that detects the voltage of the battery 2, and the battery pack 1. And a voltage detection switch 4 for connecting the battery 2 to the input side of the voltage detector 3. The voltage detector 3 has a capacitor 8 connected to the input side, a voltage detection circuit 5 that detects the voltage of the battery 2 at a predetermined cycle, and a voltage having a series resistor 6 connected to the battery 2 via the voltage detection switch 4. A detection line 10 and an arithmetic circuit 7 that calculates the voltage of the battery 2 detected by the voltage detection circuit 5 are provided. In this battery system 100, the voltage detection switch 4 is switched in order, the voltage of the battery 2 is input to the input side of the voltage detection circuit 5, and the voltage of the battery 2 is detected by the voltage detection circuit 5. Further, the arithmetic circuit 7 of the battery system 100 described above expresses the convergence voltage (V) at which the detection voltage converges from at least three detection voltages detected at a predetermined cycle by the voltage detection circuit 5 using the following equation (2). And the voltage of the battery 2 is detected from the convergence voltage (V).

ただし、この式において、
Ｙ1は、時間（ｔ）における検出電圧Ｖ(t)、
Ｙ2は、時間（ｔ＋Δｔ）における検出電圧Ｖ(t+Δt)、
Ｙ3は、時間（ｔ＋２Δｔ）における検出電圧Ｖ(t+2Δt)である。

However, in this formula:
Y1 is the detected voltage V (t) at time (t),
Y2 is the detected voltage V (t + Δt) at time (t + Δt),
Y3 is the detected voltage V (t + 2Δt) at time (t + 2Δt).

  Since the above electric vehicle can charge and discharge while accurately detecting the voltage of the battery constituting the assembled battery in a short time, it effectively prevents overcharge and overdischarge of the assembled battery, and deteriorates the assembled battery. Less life can be achieved.

  The power storage device of the present invention includes a battery system 100 that stores natural energy or late-night power, and the battery system 100 detects a battery pack 1 formed by connecting a plurality of batteries 2 in series and the voltage of the battery 2. A voltage detector 3 and a voltage detection switch 4 for connecting each battery 2 of the assembled battery 1 to the input side of the voltage detector 3 are provided. The voltage detector 3 has a capacitor 8 on the input side, a voltage detection circuit 5 that detects the voltage of the battery 2 in a predetermined cycle, and a series resistor 6 that is connected to each battery 2 via the voltage detection switch 4. A voltage detection line 10 and an arithmetic circuit 7 that calculates the voltage of the battery 2 detected by the voltage detection circuit 5 are provided. In this battery system, the voltage detection switch 4 is switched in order, the voltage of each battery 2 is input to the input side of the voltage detection circuit 5, and the voltage of the battery 2 is detected by the voltage detection circuit 5. Further, the arithmetic circuit 7 of the battery system described above calculates the convergence voltage (V) at which the detection voltage converges from the at least three detection voltages detected by the voltage detection circuit 5 in a predetermined cycle by the following equation (3). The voltage of the battery 2 is detected from the convergence voltage (V) by calculation.

ただし、これらの式において、
Ｙ1は、時間（ｔ）における検出電圧Ｖ(t)、
Ｙ2は、時間（ｔ＋Δｔ）における検出電圧Ｖ(t+Δt)、
Ｙ3は、時間（ｔ＋２Δｔ）における検出電圧Ｖ(t+2Δt)である。

However, in these equations,
Y1 is the detected voltage V (t) at time (t),
Y2 is the detected voltage V (t + Δt) at time (t + Δt),
Y3 is the detected voltage V (t + 2Δt) at time (t + 2Δt).

  The power storage device described above can charge and discharge while accurately detecting the voltage of the battery constituting the assembled battery in a short time, thus effectively preventing overcharge and overdischarge of the assembled battery and reducing deterioration of the assembled battery. Long life can be achieved.

It is a block of the battery system concerning one embodiment of the present invention. FIG. 2 is an equivalent circuit diagram showing an input side of the voltage detection circuit of the battery system shown in FIG. 1. It is a graph which shows the characteristic in which the voltage of a voltage detection circuit rises gradually from the ON state of a voltage detection switch. It is a figure which shows the state in which a voltage detection circuit detects a voltage 3 times at predetermined time intervals. It is a figure which shows the state in which a control circuit switches each voltage detection switch on / off in order. It is a figure which shows the state which the conventional battery system detects the voltage of the battery input into a voltage detection circuit. It is a flowchart in which the battery system shown in FIG. 1 detects the voltage of each battery. It is a block diagram which shows the example which mounts a battery system in the hybrid vehicle which drive | works with an engine and a motor. It is a block diagram which shows the example which mounts a battery system in the electric vehicle which drive | works only with a motor. It is a block diagram which shows the example which uses a battery system for an electrical storage apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a battery system for embodying the technical idea of the present invention, an electric vehicle including the battery system, and a power storage device. The present invention is a battery system and the battery. The electric vehicle and power storage device including the system are not specified as follows. Furthermore, this specification does not limit the members shown in the claims to the members of the embodiments.

  A battery system 100 in FIG. 1 includes an assembled battery 1 in which a plurality of batteries 2 are connected in series, a voltage detector 3 that detects the voltage of the battery 2 constituting the assembled battery 1, and the assembled battery 1. A voltage detection switch 4 for connecting each battery 2 to the input side of the voltage detector 3 is provided.

  Although the voltage detector 3 detects the voltage of each battery 2, the battery to detect is not necessarily one unit cell, for example, it can also detect the voltage of the battery which connected the several unit cell in series. . A battery system in which a unit cell is a lithium ion secondary battery or a lithium polymer battery is configured by a single unit cell, the voltage of each unit cell is detected, and the unit cell is a nickel metal hydride battery. A plurality of unit cells made of nickel metal hydride batteries are connected in series to detect the voltage of this battery as one battery. A battery system that consists of a single unit cell and detects the voltage of all unit cells can control charging and discharging while preventing overcharging and overdischarging of all unit cells. Can be prevented. In the battery system that detects the voltage of a battery in which a plurality of unit cells are connected in series, the number of batteries that detect the voltage is smaller than the number of unit cells, so the circuit configuration can be simplified and the component cost can be reduced. . Whether the battery is composed of one unit cell or a plurality of unit cells is set to an optimum state in consideration of the type of unit cell, required life characteristics, and the like.

  The voltage detector 3 is connected to each battery 2 through a voltage detection switch 4 and a voltage detection circuit 5 that detects the voltage of the battery 2 constituting the assembled battery 1 at a predetermined cycle. A voltage detection line 10 having a series resistor 6 and an arithmetic circuit 7 for calculating the voltage of the battery 2 detected by the voltage detection circuit 5.

  The voltage detection circuit 5 has a capacitor 8 connected to the input side. The capacitor 8 forms a low-pass filter 15 with the series resistor 6 of the voltage detection line 10 and the input resistor 14 connected to the input side of the voltage detection circuit 5, and a noise component input to the voltage detection circuit 5. Remove. The low-pass filter 15 lowers the cutoff frequency and removes noise components more efficiently. The cutoff frequency of the low-pass filter 15 is specified by the resistance value of the series resistor 6 and the capacitance of the capacitor 8.

  Further, the voltage detection circuit 5 of FIG. 1 has a discharge circuit 11 of a capacitor 8 connected to the input side. The discharge circuit 11 is a series circuit of a discharge resistor 12 and a discharge switch 13, and the discharge switch 13 is controlled to be turned on and off by the control circuit 9. The control circuit 9 switches on the pair of voltage detection switches 4 and detects the voltage of the battery 2 connected to the voltage detection circuit 5 via the voltage detection switch 4 in the on state, and then the pair of voltage detection switches 4. In the state of switching off, the discharge switch 13 is switched on and the capacitor 8 is discharged. Since the voltage detector 3 having the discharge circuit 11 discharges the capacitor 8 every time the voltage of the battery 2 is detected, the voltage of the battery 2 can be detected with higher accuracy. However, since the battery system of the present invention can accurately detect the voltage of the battery from the three detection voltages without discharging the capacitor, it is not always necessary to provide a discharge circuit. This is because the voltage detector that calculates the convergence voltage from the three detection voltages can accurately calculate the convergence voltage even when the capacitor 8 is not completely discharged or discharged. is there. Since the convergence voltage can be calculated from the detected voltage three times without discharging the capacitor 8, in the battery system including the discharge circuit 11, the voltage of the battery 2 is detected without completely discharging the capacitor 8 by the discharge circuit 11. You can also

  In the battery system of FIG. 1, a series resistor 6 is connected to each voltage detection line 10, and an input resistor 14 and a capacitor 8 are also connected to the input side of the voltage detection circuit 5. The input side has a circuit configuration shown in FIG. In FIG. 2, the cutoff frequency of the low-pass filter 15 is specified by the series resistance 6 of the voltage detection line 10, the input resistance 14 connected to the input side of the voltage detection circuit 5, and the capacitor 8. The cutoff frequency of the low-pass filter 15 in this circuit configuration is specified by the following formula 2.

  RC in this equation is specified by the following equation (3).

ただし、この式において、
Ｒ１は直列抵抗の抵抗値、Ｒ２は入力抵抗の抵抗値をそれぞれ示している。

However, in this formula:
R1 represents the resistance value of the series resistance, and R2 represents the resistance value of the input resistance.

  From the above formula, the cutoff frequency of the low-pass filter 15 can be lowered by increasing the resistance value of the series resistor 6 and increasing the capacitance of the capacitor 8. Since the noise component can be removed more effectively by lowering the cut-off frequency, in order for the voltage detection circuit 5 to remove the noise component and accurately detect the voltage of the battery 2, the cut-off frequency of the low-pass filter 15 is set. Low, that is, the resistance value of the series resistor 6 needs to be increased, and the capacitance of the capacitor 8 needs to be increased.

  The voltage detection circuit 5 connected with the low-pass filter 15 on the input side takes time for the voltage to rise after being connected to the battery 2 via the voltage detection switch 4 in the on state. This is because it takes time to charge the capacitor 8 on the input side. FIG. 3 shows a characteristic in which the voltage of the voltage detection circuit 5 gradually increases from the ON state of the voltage detection switch 4. The input voltage of the voltage detection circuit 5 becomes the voltage of the battery 2 in a state where the capacitor 8 is fully charged. The characteristic that the input voltage of the voltage detection circuit 5 increases varies depending on the time constant of the low-pass filter 15. The time constant is specified by the product of the resistance value constituting the low-pass filter 15 and the capacitance of the capacitor 8. Since the input voltage becomes 63.2% at the timing of the time constant, it takes several times the time constant to accurately set the input voltage of the voltage detection circuit 5 to the voltage of the battery 2. Since the low-pass filter 15 having a low cut-off frequency has a large time constant, it takes a considerable time for the voltage of the battery 2 to rise to the input voltage of the voltage detection circuit 5. Therefore, if the voltage of the battery 2 is detected after waiting for the accurate voltage of the battery 2 to be input to the voltage detection circuit 5, there is a drawback that it takes a considerable time to detect the voltage of the battery 2.

  The above battery system detects the voltage of the battery 2 in a short time from the characteristic that the voltage input to the voltage detection circuit 5 rises in order to prevent this problem. FIG. 4 shows a characteristic in which the input voltage of the voltage detection circuit 5 increases from the moment when the voltage detection switch 4 is turned on. In this figure, when the voltage detection switch 4 is turned on, the input voltage of the voltage detection circuit 5 rises to the convergence voltage over time from V1, and the following formula 6 holds.

  From the above formula 6, if the value of V (t) when t = X1, X2, X3 is Y1, Y2, Y3, the following formula 7 is obtained. However, X1 <X2 <X3.

  When Equation 7 is transformed and solved for X1, X2, and X3, the following Equation 8 is obtained.

  Here, when Δt = X2−X1 = X3−X2, the following formulas 9 and 10 hold.

  Since the left sides of Equations 9 and 10 show a constant value, Equation 11 is obtained.

  When Equation 11 is transformed and solved for V2, the following Equation 12 is obtained.

  The arithmetic circuit 7 calculates the convergence voltage (V2) from the above formula 12, and calculates the voltage (Vi) of the battery 2 based on the following formula 13 from the calculated convergence voltage. This is because the convergence voltage (V2) is input by dividing the voltage of the battery 2 by the series resistance 6 of the voltage detection line 10 and the input voltage.

  The above calculation is processed by the calculation circuit 7. In order for the arithmetic circuit 7 to calculate the voltage of the battery 2 from the convergence voltage, the voltage detection circuit 5 outputs a voltage detected at a predetermined cycle (Δt) to the arithmetic circuit 7. The voltage detection circuit 5 in FIG. 1 has an A / D converter 17 connected to the output side of a differential amplifier 16 to which the voltage of the battery 2 is input. The A / D converter 17 converts the analog signal input from the differential amplifier 16 into a digital signal at a predetermined sampling period and outputs the digital signal to the arithmetic circuit 7.

  In order for the arithmetic circuit 7 to detect the voltage of the battery 2 from the three detection voltages, the voltage detection circuit 5 detects the voltage of the battery 2 and outputs it to the arithmetic circuit 7 with a period (Δt) of 5 msec, for example. In order to detect the voltage of the battery 2 more accurately, the arithmetic circuit 7 calculates, for example, a detection voltage by averaging a plurality of voltage signals input from the voltage detection circuit 5, and from the calculated detection voltage, Equation 13 The voltage (Vi) of the battery 2 is calculated using the following equation. The arithmetic circuit 7 calculates one detection voltage by averaging three voltage signals excluding the maximum and minimum voltage signals from five voltage signals input at a sampling period of 100 μsec, for example. The voltage of the battery 2 can be detected more accurately from the repeated detection voltage at least three times. The voltage detector 3 detects five voltage signals with a sampling period of 100 μsec and outputs them to the arithmetic circuit 7 to calculate one detection voltage from the five voltage signals. The three detection voltages used for are detected with a period (Δt) of 5 msec. Thus, in the method of calculating a single detection voltage by averaging a plurality of voltage signals, the sampling period of the plurality of voltage signals can be set to 1 μsec to 2 msec, for example. However, the voltage detection circuit 5 can also calculate the voltage of the battery 2 using the three voltage signals input from the voltage detection circuit 5 as detection voltages without averaging a plurality of voltage signals. Further, the period (Δt) of the three detection voltages calculated by the battery 2 by the arithmetic circuit 7 is not specified to 5 msec. Shorter than. The cycle for detecting the voltage used for the calculation can be shortened to detect the voltage of the battery 2 in a shorter time. However, if the time for detecting the voltage of the battery 2 is shortened, it is necessary to use an electronic component for high-speed processing as the electronic component to be used, and the component cost increases. Therefore, the sampling period in which the voltage detection circuit 5 detects the voltage of the battery 2 is set to an optimum value in consideration of the component cost and the time required for detecting the leakage.

  In order to detect the voltage of each battery 2 constituting the assembled battery 1 in order, the voltage detection switch 4 is controlled to be turned on and off at a predetermined cycle by the control circuit 9 to sequentially detect the voltage of each battery 2. Input to the device 3. FIG. 5 shows a state in which the control circuit 9 switches each voltage detection switch 4 on and off in order. In the voltage detection switch 4, a pair of voltage detection switches 4 connected to a pair of input terminals of the voltage detection circuit 5 are simultaneously turned on, and the voltage of one battery 2 is input to the voltage detector 3. In a state where the pair of voltage detection switches 4 are turned on, all the other voltage detection switches 4 are held in the off state. As shown in FIG. 5, the voltage input to the voltage detection circuit 5 gradually increases at the timing when the pair of voltage detection switches 4 are turned on. At this timing, at least three times at a predetermined cycle (Δt). The convergence voltage (V) is calculated from the detected voltage, and the voltage of the battery 2 is calculated from the convergence voltage.

  FIG. 6 is a diagram illustrating a state in which the battery voltage is detected after the voltage input to the voltage detection circuit has converged, that is, a state in which the conventional battery system detects the battery voltage. As shown in this figure, the battery system that detects the voltage of the battery without calculating the convergence voltage detects the voltage after waiting until the voltage input to the voltage detection circuit converges. Has the disadvantage that it takes a considerable amount of time. In addition, since the amount of electricity charged in the capacitor 8 is increased by waiting for the voltage input to the voltage detection circuit 5 to converge, the charged capacitor 8 is discharged to the discharge circuit after detecting the voltage of each battery 2. The discharge time at 11 also becomes longer. Therefore, as shown in FIG. 6, the detection period (T) for detecting the voltage of each battery 2 becomes longer, and the time required for detecting the voltages of all the batteries becomes considerably longer.

  On the other hand, as shown in FIG. 4, the battery system of the present invention detects at least three detection voltages at a predetermined period (Δt) (for example, 5 msec) and calculates a convergence voltage from the detection voltages. Since the voltage of the battery 2 is detected, the time required to detect the voltage of the battery 2 can be shortened (for example, about 10 msec). Furthermore, since the voltage of the battery 2 is detected without waiting for the voltage input to the voltage detection circuit 5 to converge, the amount of electricity charged in the capacitor 8 can be reduced, and charging is performed after detecting the voltage of each battery 2. The time for discharging the capacitor 8 discharged by the discharge circuit 11 can also be shortened. Therefore, as shown in FIG. 5, in a state where the voltage detection switches 4 are switched in order and the voltages of the plurality of batteries 2 are detected in order, the detection cycle (T) for detecting the voltage of each battery 2 is shortened. The time required for voltage detection of all the batteries 2 can be shortened.

  The battery system of FIG. 1 detects the voltage of each battery 2 constituting the assembled battery 1 in the flowchart of FIG. 7 shown below.

[Steps of S = 1, 2]
The pair of voltage detection switches 4 (SW1) constituting the assembled battery 1 are switched on, and all other voltage detection switches 4 are turned off. Initially, n = 1 is set, only the first voltage detection switches SW1a and SW1b are turned on, and all other voltage detection switches 4 are turned off.

[Step S = 3]
In this step, the arithmetic circuit 7 calculates a convergence voltage from at least three detection voltages input from the voltage detection circuit 5, and calculates a first battery voltage Vc1 from the convergence voltage.

[Step S = 4]
After detecting the first battery voltage Vc1, the first voltage detection switches SW1a and SW1b that are in the on state are switched to the off state. Even in this state, all other voltage detection switches 4 are turned off.

[Step S = 5]
In this step, the discharge switch 13 (SW7) of the discharge circuit 11 is turned on to discharge the capacitor 8. Although the discharge switch 13 discharges the capacitor 8, it is not always necessary to discharge the capacitor 8 completely. This is because even when the capacitor 8 is not completely discharged, the convergence voltage can be accurately calculated from the three detection voltages based on Equation 1.

[Steps S = 6, 7]
It loops to the step of S = 2 until the voltage of all the batteries 2 is detected. Each time the process loops to the step S = 2, 1 is added to n, and in the steps S = 2 to 5, the voltage detection switch 4 is sequentially turned on, and the voltage detection switch 4 is turned on. Thus, the voltage of the battery 2 connected to the voltage detection circuit 5 is detected.

  The battery system described above detects the voltage of each battery 2 by connecting the positive and negative electrodes of each battery 2 sequentially to the input terminal of the voltage detection circuit 5 via a pair of voltage detection switches 4. However, the present invention does not specify the voltage detection circuit as the above circuit configuration. For example, although not illustrated, the voltage difference between the positive and negative electrodes of the battery connected in series is sequentially detected and detected. From the above, it is possible to adopt a circuit configuration for detecting the voltage of each battery.

  The above battery system can be used as an in-vehicle power source. As a vehicle equipped with a battery system, an electric vehicle such as a hybrid vehicle or a plug-in hybrid vehicle that runs with both an engine and a motor, or an electric vehicle that runs only with a motor can be used and used as a power source for these vehicles. .

(Battery system for hybrid vehicles)
FIG. 8 shows an example in which a battery system is mounted on a hybrid vehicle that runs with both an engine and a motor. A vehicle HV equipped with the battery system shown in this figure includes an engine 96 and a running motor 93 that run the vehicle HV, a battery system 100 that supplies power to the motor 93, and a generator that charges a battery of the battery system 100. 94, a vehicle main body 90 on which an engine 96, a motor 93, a battery system 100, and a generator 94 are mounted, and wheels 97 that are driven by the engine 96 or the motor 93 to run the vehicle main body 90. The battery system 100 is connected to a motor 93 and a generator 94 via a DC / AC inverter 95. The vehicle HV travels by both the motor 93 and the engine 96 while charging / discharging the battery of the battery system 100. The motor 93 is driven to drive the vehicle when the engine efficiency is low, for example, during acceleration or low-speed driving. The motor 93 is driven by power supplied from the battery system 100. The generator 94 is driven by the engine 96 or is driven by regenerative braking when the vehicle is braked to charge the battery of the battery system 100.

(Battery system for electric vehicles)
FIG. 9 shows an example in which a battery system is mounted on an electric vehicle that runs only with a motor. A vehicle EV equipped with the battery system shown in this figure includes a traveling motor 93 that travels the vehicle EV, a battery system 100 that supplies electric power to the motor 93, and a generator 94 that charges the battery of the battery system 100. And a vehicle main body 90 on which the motor 93, the battery system 100, and the generator 94 are mounted, and wheels 97 that are driven by the motor 93 and run the vehicle main body 90. The battery system 100 is connected to a motor 93 and a generator 94 via a DC / AC inverter 95. The motor 93 is driven by power supplied from the battery system 100. The generator 94 is driven by energy when regeneratively braking the vehicle EV, and charges the battery of the battery system 100.

(Battery system for power storage device)
Furthermore, this battery system can be used not only as a power source for a mobile body but also as a stationary power storage facility. For example, as a power source for home and factory use, a power supply system that is charged with sunlight or midnight power and discharged when necessary, or a streetlight power supply that charges sunlight during the day and discharges at night, or during a power outage It can also be used as a backup power source for driving signals. Such an example is shown in FIG. The battery system 100 shown in this figure forms a battery unit 82 by connecting a plurality of battery blocks 81 in a unit form. Each battery block 81 has a plurality of unit cells 1 connected in series and / or in parallel. Each battery block 81 is controlled by a power supply controller 84. The battery system 100 drives the load LD after charging the battery unit 82 with the charging power source CP. For this reason, the battery system 100 includes a charge mode and a discharge mode. The load LD and the charging power source CP are connected to the battery system 100 via the discharging switch DS and the charging switch CS, respectively. ON / OFF of the discharge switch DS and the charge switch CS is switched by the power supply controller 84 of the battery system 100. In the charging mode, the power controller 84 switches the charging switch CS to ON and the discharging switch DS to OFF to permit charging of the battery system 100 from the charging power source CP. Further, when the charging is completed and the battery is fully charged, or in response to a request from the load LD in a state where a capacity of a predetermined value or more is charged, the power controller 84 turns off the charging switch CS and turns on the discharging switch DS to discharge. The mode is switched and discharging from the battery system 100 to the load LD is permitted. Further, if necessary, the charge switch CS can be turned on and the discharge switch DS can be turned on to supply power to the load LD and charge the battery system 100 simultaneously.

  A load LD driven by the battery system 100 is connected to the battery system 100 via a discharge switch DS. In the discharge mode of the battery system 100, the power supply controller 84 switches the discharge switch DS to ON, connects to the load LD, and drives the load LD with the power from the battery system 100. As the discharge switch DS, a switching element such as an FET can be used. ON / OFF of the discharge switch DS is controlled by the power supply controller 84 of the battery system 100. The power controller 84 also includes a communication interface for communicating with external devices. In the example of FIG. 10, it is connected to the host device HT according to an existing communication protocol such as UART or RS-232c. Further, if necessary, a user interface for the user to operate the power supply system can be provided.

  Each battery block 81 includes a signal terminal and a power supply terminal. The signal terminals include an input / output terminal DI, an abnormal output terminal DA, and a connection terminal DO. The input / output terminal DI is a terminal for inputting / outputting a signal from the other battery block 81 or the power supply controller 84, and the connection terminal DO is a terminal for inputting / outputting a signal to / from the other battery block 81. . The abnormality output terminal DA is a terminal for outputting abnormality of the battery block 81 to the outside. Furthermore, the power supply terminal is a terminal for connecting the battery blocks 81 in series and in parallel. The battery units 82 are connected to the output line OL via the parallel connection switch 85 and connected in parallel to each other.

  The battery system of the present invention can be suitably used for an electric vehicle such as an electric vehicle or a hybrid vehicle, or for storing natural energy such as a solar battery 2 power generation device or wind power generation, or a power storage device for midnight power.

DESCRIPTION OF SYMBOLS 100 ... Battery system 1 ... Assembly battery 2 ... Battery 3 ... Voltage detector 4 ... Voltage detection switch 5 ... Voltage detection circuit 6 ... Series resistance 7 ... Arithmetic circuit 8 ... Capacitor 9 ... Control circuit 10 ... Voltage detection line 11 ... Discharge circuit DESCRIPTION OF SYMBOLS 12 ... Discharge resistance 13 ... Discharge switch 14 ... Input resistance 15 ... Low pass filter 16 ... Differential amplifier 17 ... A / D converter 81 ... Battery block 82 ... Battery unit 84 ... Power supply controller 85 ... Parallel connection switch 90 ... Vehicle main body 93 ... Motor 94 ... Generator 95 ... DC / AC inverter 96 ... Engine 97 ... Wheel EV ... Vehicle HV ... Vehicle LD ... Load CP ... Power supply for charging DS ... Discharge switch CS ... Charge switch OL ... Output line HT ... Host equipment DI ... On Output terminal DA ... Abnormal output terminal DO ... Connection terminal

Claims (6)

A battery system comprising an assembled battery formed by connecting a plurality of batteries in series, a voltage detector for detecting the voltage of the battery, and a voltage detection switch for connecting the battery of the assembled battery to the input side of the voltage detector. Because
The voltage detector has a voltage detection circuit that connects a capacitor on the input side and detects the voltage of the battery at a predetermined period (Δt), and a voltage having a series resistance connected to the battery via the voltage detection switch A detection line, and an arithmetic circuit for calculating the voltage of the battery detected by the voltage detection circuit,
The voltage detection switch is switched in order, the battery voltage is input to the input side of the voltage detection circuit, the battery voltage is detected by the voltage detection circuit,
The arithmetic circuit calculates a convergence voltage (V) at which the detection voltage converges from at least three detection voltages detected at a predetermined cycle (Δt) by the voltage detection circuit by the following equation (14): A battery system characterized by detecting a voltage of a battery from a convergence voltage (V).

However, in this formula:
Y1 is the detected voltage V (t) at time (t),
Y2 is the detected voltage V (t + Δt) at time (t + Δt),
Y3 is the detected voltage V (t + 2Δt) at time (t + 2Δt).   2. The battery system according to claim 1, wherein an input terminal of the voltage detection circuit is connected to positive and negative electrodes of the battery via a pair of voltage detection switches and a voltage detection line to detect the voltage of the battery.   The battery system according to claim 1, wherein a discharge circuit that discharges the capacitor when the voltage detection switch is off is connected to an input side of the voltage detection circuit.   4. An input resistor is connected to the input side of the voltage detection circuit, and the voltage of the battery is divided by this input resistance and the series resistor and input to the voltage detection circuit. Battery system. An electric vehicle comprising the battery system according to any one of claims 1 to 4,
An electric vehicle in which the battery system supplies power to a motor that drives the vehicle. A power storage device comprising the battery system according to any one of claims 1 to 4,
A power storage device in which the battery system stores natural energy or midnight power.

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