JP7435527B2 - battery measurement system - Google Patents

Description

The present invention relates to a battery measurement system.

Conventionally, in order to measure the state of a storage battery, the complex impedance of a storage battery has been measured (for example, Patent Document 1). In the invention described in Patent Document 1, a power control unit applies a rectangular wave signal to a storage battery, and a complex impedance characteristic is calculated based on the response signal. Based on this complex impedance characteristic, the state of deterioration of the storage battery was determined.

Furthermore, there is a known technique in which an AC signal is sent from an oscillator to an object under test, the response signal (voltage fluctuation) is detected by a lock-in amplifier, and complex impedance characteristics are calculated based on the detection result (Patent Document 2). According to this technology, it is possible to extract only the frequency component that is desired to be measured using the detected voltage amplitude with high sensitivity and remove noise.

Japanese Patent Application Publication No. 2008-175556 Japanese Patent Application Publication No. 2012-217625

By the way, impedance is detected based on the AC signal input to the storage battery and the voltage fluctuation of the storage battery when the AC signal is input. In the case of in-vehicle storage batteries, the drive current and regenerative current from the main engine, as well as the current supplied to the auxiliary equipment through the DC/DC converter, generally mix in as noise, making it difficult to accurately measure AC signals. Therefore, information regarding the AC signal input to the storage battery (amplitude, frequency, and phase) needs to be obtained from an AC signal input device (power control unit in the example of Patent Document 1) or an instruction device that instructs input of the AC signal. There is.

However, among the information regarding AC signals, the phase is time-related information (timing-related information) and can only be sent as analog information. Therefore, if the wiring from the input device etc. to the detection circuit that detects the impedance of the storage battery (the battery monitoring unit in the example of Patent Document 1) is long, information regarding the phase of the AC signal is transmitted from the input device etc. to the detection circuit. However, a phase shift will occur due to communication delays. Furthermore, since a phase shift occurs in the reference AC signal, it has been difficult to accurately detect the impedance of each battery cell.

Furthermore, in a vehicle-mounted battery pack, it is often difficult to arrange an input device or the like near a detection circuit due to design considerations.

The present invention has been made in view of the above circumstances, and its main purpose is to provide a battery measurement system that can accurately detect impedance.

Means for solving the above problem is provided in a battery measurement system that measures the state of each battery cell of an assembled battery in which a plurality of battery cells are connected in series. The cells are divided in advance into cell blocks consisting of one or more battery cells, and include a first control section that instructs a predetermined alternating current signal, and a first control section that instructs the assembled battery to receive the alternating current signal based on the instructions of the first control section. a reference signal corresponding to the AC signal determined based on at least one of the information from the first control unit and the measurement result of the current sensor; and the AC signal is applied to the assembled battery. a first detection unit that detects the impedance of the assembled battery based on voltage fluctuations of the assembled battery measured when a second detection unit that detects impedance of each cell block based on a voltage fluctuation of the cell block measured when the alternating current signal is applied to the battery pack; By comparing a vector sum value obtained by summing up the impedances of the cell blocks detected by the unit and a vector value as the impedance of the assembled battery detected by the first detection unit, the reference signal and the A correction unit that specifies a phase difference between temporary signals and corrects a phase of impedance of each cell block based on the phase difference.

Information related to phase is information related to time, that is, information related to timing, and can only be sent as analog information. Therefore, if the wiring between the first control section that instructs the AC signal and the second detection section that detects the impedance of each cell block is long, the AC signal is transmitted from the first control section to the second detection section. Even if information regarding the phase is transmitted, a phase shift will occur due to communication delay. On the other hand, it is difficult in terms of design to arrange the first control section and the second detection section close to each other. In addition, in the case of a vehicle-mounted battery pack, since auxiliary equipment is generally connected, noise from the main engine and auxiliary equipment is often mixed in. For this reason, it is difficult to accurately measure the AC signal flowing through the assembled battery.

Therefore, in the above means, by comparing the vector sum value obtained by summing up the impedance of each cell block detected by the second detection section and the vector value as the impedance of the assembled battery detected by the first detection section, , the phase difference between the reference signal and the temporary signal was identified. A correction unit is provided that corrects the impedance phase of each cell block based on the phase difference. This makes it possible to accurately detect the impedance of each cell block.

FIG. 1 is a diagram schematically showing a battery measurement system. FIG. 1 is a diagram schematically showing an impedance calculation device. FIG. 3 is a diagram showing impedance detection timing. Flowchart showing the flow of signal determination processing. 5 is a flowchart showing the flow of individual impedance detection processing. 5 is a flowchart showing the flow of correction processing. FIG. 3 is a diagram for explaining the relationship between the vector summation value of impedance of battery cells and the impedance of an assembled battery. FIG. 2 is a diagram schematically showing a battery measurement system according to a second embodiment. FIG. 7 is a diagram showing impedance detection timing in the second embodiment. The figure which shows the 2nd impedance detection apparatus in 3rd Embodiment. FIG. 7 is a diagram showing the input/output timing of synchronization signals in the third embodiment. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example. FIG. 6 is a diagram schematically showing a battery measurement system according to a modified example.

(First embodiment)
Hereinafter, an embodiment in which a "battery measurement system" is applied to a vehicle (for example, a hybrid vehicle or an electric vehicle) will be described with reference to the drawings. Note that in each of the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the explanations thereof will be referred to for the parts with the same reference numerals.

As shown in FIG. 1, the battery measurement system 100 includes a battery pack 10, a current control device 20 connected to the battery pack 10 and capable of inputting a predetermined alternating current signal (alternating current) to the battery pack 10, A battery monitoring device 30 connected to the battery 10 and monitoring the assembled battery 10 is provided.

The assembled battery 10 has a terminal voltage of, for example, 100 V or more, and has a plurality of (six in this embodiment) battery cells 11i (i=1, 2, 3, 4, 5, 6, the same applies hereinafter). They are connected in series. For example, a lithium ion storage battery or a nickel hydride storage battery can be used as the battery cell 11i.

The current control device 20 is connected to the assembled battery 10 via the system relay switch SMR, and includes a current application device 21 as a signal application section configured to be able to apply a predetermined alternating current signal (alternating current); The battery pack includes a first control device 22 as a first control section that instructs input and impedance detection, and a first impedance detection device 23 as a first detection section that detects the impedance of the assembled battery 10.

The current applying device 21 is, for example, a power converter such as an inverter or a converter that is connected to a motor (not shown) and controls the motor. The current application device 21 applies (inputs) an AC signal having the specified amplitude Is, frequency fs, and phase θs to the assembled battery 10 in accordance with instructions from the first control device 22 . Note that in this embodiment, the alternating current signal is an alternating current having a sinusoidal current waveform.

The first control device 22 is mainly composed of a microcomputer equipped with a CPU, ROM, RAM, I/O, etc., and realizes various functions by the CPU executing programs stored in the ROM. . Note that the various functions may be realized by electronic circuits that are hardware, or may be realized at least in part by software, that is, processing executed on a computer. Further, the first control device 22 may be realized by an MGECU that controls the motor via an inverter or the like. In other words, the MGECU may have various functions as the first control section.

The first control device 22 has a function of instructing the current applying device 21 about the amplitude Is, frequency fs, and phase θs of the AC signal, and causing the AC signal to be applied to the assembled battery 10 . Other functions include a function of instructing the first impedance detection device 23 to detect the impedance of the assembled battery 10, a function of communicating with the battery monitoring device 30, and a function of correcting impedance. Various functions will be described later.

The first impedance detection device 23 includes a first sine wave generation circuit 24 as a first signal generation section and a first lock-in amplifier 25 as a first calculation section. The first sine wave generation circuit 24 converts the AC signal applied by the current application device 21 to the assembled battery 10 based on the information (amplitude Is, frequency fs, and phase θs) of the AC signal input from the first control device 22. On the other hand, a reference signal Ref1 (current signal) having the same amplitude Is, frequency fs, and phase θs is generated. Then, the first sine wave generation circuit 24 outputs the generated reference signal Ref1 to the first lock-in amplifier 25 as a reference signal.

As shown in FIG. 2, the first lock-in amplifier 25 is a two-phase lock-in amplifier. The outline will be explained below. The first lock-in amplifier 25 includes a phase shift circuit 51, multipliers 52 and 62, integrators 53 and 63, low-pass filters 54 and 64, an impedance calculation circuit 55, and the like.

By inputting the reference signal Ref1, the phase shift circuit 51 generates a second reference signal Ref2, which is a sine wave current whose phase is shifted by 90 degrees (90°) with respect to the reference signal Ref1. This second reference signal Ref2 is output to the multiplier 62. Below, the reference signal Ref1 will be referred to as a first reference signal Ref1. Further, in the first lock-in amplifier 25, the voltage fluctuation Va (voltage signal) of the assembled battery 10 is input to the multipliers 52 and 62 via a filter (such as a bandpass filter) and an A/D converter. The voltage fluctuation Va of the assembled battery 10 is a voltage fluctuation as a response signal generated based on the application of an AC signal to the assembled battery 10 (disturbance).

The multiplier 52 calculates a multiplication value X by multiplying the voltage fluctuation Va of the assembled battery 10 by the first reference signal Ref<b>1 and outputs it to the integrator 53 . The integrator 53 averages the input multiplication value X and outputs it to the impedance calculation circuit 55 via the low-pass filter 54. Thereby, the impedance calculation circuit 55 receives the real part Re_Va of the voltage fluctuation Va of the battery pack 10 as input.

Further, the multiplier 62 calculates a multiplication value Y by multiplying the voltage fluctuation Va by the second reference signal Ref2, and outputs the product to the integrator 63. The integrator 63 averages the input multiplication value Y and outputs it to the impedance calculation circuit 55 via the low-pass filter 64. As a result, the impedance calculation circuit 55 receives the imaginary part Im_Va of the voltage fluctuation Va of the assembled battery 10.

The impedance calculation circuit 55 calculates the absolute value Za (scalar value) and phase θa of the impedance of the assembled battery 10 based on equations (1) and (2), and outputs them to the first control device 22. In the present embodiment, the impedance calculation circuit 55 calculates the absolute value Za and phase θa of the impedance of the assembled battery 10, but the first control device 22 inputs the real part Re_Va and the imaginary part Im_Va of the voltage fluctuation Va. , may be calculated.

In addition, since the first lock-in amplifier 25 uses integrators 53, 63 and low-pass filters 54, 64, from the start of calculation (measurement) to the calculation of the absolute value Za and phase θa of impedance. requires time. Although this time depends on the integration time and filter time constant, for example, as shown in FIG. 3, the sampling time Ts may be about 8 cycles (8/fs) of the first reference signal Ref1. .

This first lock-in amplifier 25 makes it possible to extract only the frequency component corresponding to the first reference signal Ref1 (=AC signal) out of the voltage fluctuation Va with high sensitivity and remove noise. . Hereinafter, the absolute value Za and phase θa of the impedance of the assembled battery 10 detected by the first lock-in amplifier 25 may be referred to as impedance (Za, θa).

Next, the battery monitoring device 30 will be explained. As shown in FIG. 1, the battery monitoring device 30 includes a second control device 31 as a second control section, and impedance control of each battery cell 11i (i=1, 2, 3, 4, 5, 6, the same applies hereinafter). and a second impedance detection device 32 as a second detection section that individually detects the impedance.

The second control device 31 is mainly composed of a microcomputer equipped with a CPU, ROM, RAM, I/O, etc., and realizes various functions by the CPU executing programs stored in the ROM. . Note that the various functions may be realized by electronic circuits that are hardware, or may be realized at least in part by software, that is, processing executed on a computer.

The second control device 31 has a function of communicating with the current control device 20, a function of determining a temporary signal Tem1 related to the AC signal, a function of detecting the impedance of each battery cell 11i, and the like. Various functions will be described later.

The second impedance detection device 32 includes a second sine wave generation circuit 33 as a second signal generation section, and a plurality of (six in this embodiment) second lock-in amplifiers 34i (i=1 , 2, 3, 4, 5, 6, hereinafter the same).

The second sine wave generation circuit 33 generates a temporary signal Tem1 related to the AC signal based on instructions from the second control device 31. Specifically, the second sine wave generation circuit 33 generates a temporary signal Tem1 having the same amplitude Is and frequency fs as the AC signal. That is, the temporary signal Tem1 has the same amplitude Is and frequency fs as the first reference signal Ref1. Note that the phase θt of the temporary signal Tem1 is arbitrary. In this embodiment, it is set based on an instruction from the second control device 31, but it may also be determined by the second sine wave generation circuit 33.

The second lock-in amplifier 34i is provided for each battery cell 11i to be monitored, and individually detects the impedance of the battery cell 11i to be monitored based on the temporary signal Tem1. In this embodiment, each battery cell 11i corresponds to a cell block. The second lock-in amplifier 34i is a two-phase lock-in amplifier similarly to the first lock-in amplifier 25, and has the same configuration, so a detailed description thereof will be omitted.

Note that the voltage fluctuation of each battery cell 11i is expressed as voltage fluctuation Vi (i=1, 2, 3, 4, 5, 6, the same applies hereinafter), and the voltage fluctuation Vi is the voltage fluctuation in the description of the first lock-in amplifier 25. Corresponds to Va. Further, the absolute value of the impedance of each battery cell 11i is indicated as an absolute value Zi (i=1, 2, 3, 4, 5, 6, the same applies hereinafter), and the absolute value Zi is the same as in the description of the first lock-in amplifier 25. It corresponds to the absolute value Za. Similarly, the phase of the impedance of each battery cell 11i is expressed as phase θi (i=1, 2, 3, 4, 5, 6, the same applies hereinafter), and the phase θi is the phase θa in the description of the first lock-in amplifier 25. corresponds to As described above, the second lock-in amplifier 34i detects the absolute value Zi and phase θi of the impedance of each battery cell 11i.

At this time, the second lock-in amplifier 34i uses the temporary signal Tem1 as a reference (reference signal) and calculates the absolute value Zi and phase θi of the impedance of each battery cell 11i based on the temporary signal Tem1 and the voltage fluctuation Vi of the battery cell 11i. Detect. Therefore, there is a high possibility that the detected impedance (true impedance) of each battery cell 11i is out of phase with respect to the AC signal (first reference signal Ref1). Therefore, in order to distinguish it from the true impedance detected based on the AC signal, the absolute value Zi and phase θi of the impedance of each battery cell 11i detected by the second lock-in amplifier 34i are converted into temporary impedance (Zi, phase θi). It may be indicated as Furthermore, the detected impedance of each battery cell 11i may be distinguished from the true impedance (Zsi, phase θsi) based on the AC signal (first reference signal Ref1).

Note that in this embodiment, one second sine wave generation circuit 33 is provided in the second impedance detection device 32, and the second sine wave generation circuit 33 is connected to all the second lock-in amplifiers 34i. There is. Then, the second sine wave generation circuit 33 generates a temporary signal Tem1 based on an instruction from the second control device 31, and outputs it to each second lock-in amplifier 34i. Therefore, the temporary signals Tem1 can be synchronized between the second lock-in amplifiers 34i. That is, each second lock-in amplifier 34i receives the temporary signal Tem1 having the same amplitude Is, frequency fs, and phase θt.

By the way, the phase θs of the AC signal is time-related information (timing-related information) and can only be sent as an analog signal (analog information). In other words, if the wiring between the first control device 22 and the second control device 31 is long, even if the first control device 22 transmits information regarding the phase θs of the AC signal to the second control device 31, It is difficult to accurately convey the phase θs due to communication delays and noise. In other words, a shift occurs in the phase θs during communication. In addition, when an inverter is adopted as the current application device 21, since the inverter and the assembled battery 10 are generally placed apart from each other in a vehicle, the There is a high possibility that the wiring will be longer. It is also conceivable to provide a current application device 21, which is separate from devices such as an inverter that are supposed to be installed in the vehicle, near the assembled battery 10, but in this case, manufacturing costs will increase and the size will increase. Become.

Further, in the case of the assembled battery 10 for use in a vehicle, since auxiliary equipment is generally connected, noise due to the auxiliary equipment often flows into the assembled battery 10. For this reason, it is difficult to measure the current flowing through the assembled battery 10 and extract the AC signal (reference current waveform) applied from the current application device 21.

Therefore, it is difficult for the battery monitoring device 30 to specify the phase θs of the AC signal flowing through the assembled battery 10 and to cause the second impedance detection device 32 to generate the same signal as the first reference signal Ref1. There is. In other words, there is a high possibility that the temporary impedance detected by the second lock-in amplifier 34i has a phase shift with respect to the true impedance.

Therefore, in this embodiment, the phase shift of the temporary impedance detected by the second lock-in amplifier 34i is corrected and the true impedance is calculated by performing the following processing. This will be explained in detail below.

The current control device 20 executes the signal determination process shown in FIG. 4 at a predetermined timing. In the signal determination process, first, the first control device 22 of the current control device 20 determines the frequency fs of an AC signal that becomes a reference current to be passed through the assembled battery 10 (step S101). Next, the first control device 22 determines the amplitude Is of the AC signal (step S102). Then, the first control device 22 generates a digital signal (digital information) regarding the determined frequency fs and amplitude Is of the AC signal, and outputs (transmits) it to the second control device 31 (step S103). The first control device 22 also determines the phase θs of the AC signal (step S104). Then, the first control device 22 controls the current applying device to apply (input) to the assembled battery 10 an AC signal having an amplitude Is, a frequency fs, and a phase θs determined in the signal determination process. 21 (step S105). When the current application device 21 is an inverter, the first control device 22 instructs (controls) on/off of various switches that constitute the inverter.

The current control device 20 then ends the signal determination process. After the signal determination process is completed, the current control device 20 executes the correction process shown in FIG. 6. The correction process may be executed immediately after the end of the signal determination process, or may be executed after a predetermined period of time has elapsed. Further, the correction process may be executed at a predetermined timing.

Next, the temporary impedance detection process executed by the battery monitoring device 30 will be described based on FIG. 5. The temporary impedance detection process may be executed at the timing when the digital signal is input from the first control device 22 of the current control device 20, or may be executed after a predetermined period of time has passed after the digital signal is input. . Further, it may be executed at predetermined intervals.

When the second control device 31 of the battery monitoring device 30 inputs (receives) a digital signal (digital information) regarding the frequency fs and amplitude Is of the AC signal from the first control device 22, it receives the frequency fs and amplitude Is of the AC signal from the digital signal. Is is acquired (step S201). Next, the second control device 31 sets the amplitude Is, frequency fs, and phase θt of the temporary signal Tem1 (step S202). Specifically, based on the frequency fs and amplitude Is acquired in step S201, the frequency and amplitude of the temporary signal Tem1 are set so that the frequency and amplitude of the AC signal and the temporary signal Tem1 are the same. That is, the frequency and amplitude of the temporary signal Tem1 are set to the frequency fs and amplitude Is obtained in step S201, respectively. Further, the phase θt of the temporary signal Tem1 is set to an arbitrary phase.

Next, the second control device 31 instructs the amplitude Is, frequency fs, and phase θt of the temporary signal Tem1, and starts detecting the temporary impedance (Zi, θi) of each battery cell 11i (step S203). That is, the second control device 31 instructs the second impedance detection device 32 to detect the temporary impedance of each battery cell 11i.

When the second sine wave generation circuit 33 of the second impedance detection device 32 receives an instruction from the second control device 31, it generates a temporary signal Tem1 according to the instruction and outputs it to the second lock-in amplifier 34i ( Step S204). At this time, the temporary signal Tem1 is generated so that the amplitude, frequency, and phase of the temporary signal Tem1 become the amplitude Is, frequency fs, and phase θt instructed by the second control device 31.

Each second lock-in amplifier 34i obtains the voltage fluctuation Vi of each battery cell 11i to be monitored until a predetermined sampling time Ts has elapsed (step S205). As described above, each second lock-in amplifier 34i detects the temporary impedance (Zi, θi) of each battery cell 11i based on the voltage fluctuation Vi of each battery cell 11i and the temporary signal Tem1 ( Step S206).

The second control device 31 acquires the temporary impedance (Zi, θi) detected from each second lock-in amplifier 34i, and outputs (transmits) it to the first control device 22 of the current control device 20 (step S207). Then, the battery monitoring device 30 ends the individual impedance detection process.

The next correction process will be explained based on FIG. 6. The first control device 22 of the current control device 20 causes the current application device 21 to apply an AC signal to the assembled battery 10, and then instructs the amplitude Is, frequency fs, and phase θs of the first reference signal Ref1, and then controls the assembled battery. Detection of the impedance (Za, θa) of 10 is started (step S301). That is, the first control device 22 instructs the first impedance detection device 23 to detect the impedance of the assembled battery 10. At this time, the amplitude Is, frequency fs, and phase θs of the first reference signal Ref1 are the same as the amplitude Is, frequency fs, and phase θs of the AC signal.

When the first sine wave generation circuit 24 of the first impedance detection device 23 receives an instruction from the first control device 22, it generates a first reference signal Ref1 according to the instruction, and outputs the first reference signal Ref1 to the first lock-in amplifier 25. Output (step S302).

The first lock-in amplifier 25 acquires the voltage fluctuation Va of the assembled battery 10 until the predetermined sampling time Ts has elapsed (step S303). Then, as described above, the first lock-in amplifier 25 detects the impedance (Za, θa) of the battery pack 10 based on the voltage fluctuation Va of the battery pack 10 and the first reference signal Ref1 (step S304). ). The first control device 22 acquires the impedance (Za, θa) of the assembled battery 10 detected from the first lock-in amplifier 25 (step S305). The first control device 22 also inputs (receives) the temporary impedance (Zi, θi) of each battery cell 11i output from the second control device 31 (step S306). Note that step S306 may be executed at any timing before step S307 is executed.

Here, the current application device 21, the first control device 22, and the first impedance detection device 23 are configured in a closed circuit within the current control device 20, and are configured to be less susceptible to external noise. There is. In addition, the current application device 21, the first control device 22, and the first impedance detection device 23 are arranged close to each other, so that the wiring connecting them is shortened, and when inputting and outputting the phase θs, there is no misalignment. Hard to occur. Therefore, it is possible to accurately transmit the amplitude Is, frequency fs, and phase θs between the current application device 21 and the first control device 22 and between the first control device 22 and the first impedance detection device 23. can.

Therefore, when detecting the impedance (Za, θa) of the assembled battery 10 using the lock-in amplifier method, the first reference signal Ref1 has amplitude Is, frequency fs, and phase with respect to the AC signal input to the assembled battery 10. θs are the same.

Furthermore, since the first control device 22 transmits the amplitude Is and frequency fs of the AC signal to the second control device 31 as digital information, the amplitude of the temporary signal Tem1 set by the second control device 31 is and the frequency are the same as the AC signal (and the first reference signal Ref1). On the other hand, the phase θt of the temporary signal Tem1 is arbitrarily set by the second control device 31, so the phase θt of the temporary signal Tem1 is different from the AC signal (and the first reference signal Ref1).

Further, the second control device 31 and the second impedance detection device 32 are configured in a closed circuit within the battery monitoring device 30, and are configured to be less susceptible to external noise. Further, the second control device 31 and the second impedance detection device 32 are arranged close to each other, so that the wiring connecting them to each other is shortened, and a shift is less likely to occur when inputting and outputting the phase θt. Therefore, the amplitude Is, the frequency fs, and the phase θt can be accurately transmitted between the second control device 31 and the second impedance detection device 32.

In the assembled battery 10, the battery cells 11i are connected in series, and the amplitude and frequency of the AC signal, the reference signal Ref1, and the temporary signal Tem1 are the same. From the above, the absolute value Za of the impedance of the battery pack 10 is the same as the absolute value (magnitude) of the vector sum of the temporary impedances (Zi, θi). On the other hand, depending on the phase difference (θt−θs) between the first reference signal Ref1 and the temporary signal Tem1, the phase θa of the impedance of the assembled battery 10 and the phase of the vector sum of the temporary impedances (Zi, θi) are determined. will be shifted.

Here, the above principle will be explained in detail based on FIG. 7. Note that, in order to simplify the explanation, FIG. 7 will be described with the number of battery cells 11i constituting the assembled battery 10 being three, but the theory is the same regardless of the number of battery cells 11i. In the following, the temporary impedance of the battery cell 111 is denoted as temporary impedance (Z1, θ1), the temporary impedance of the battery cell 112 is denoted as temporary impedance (Z2, θ2), and the temporary impedance of the battery cell 113 is denoted as temporary impedance ( Z3, θ3).

As shown in FIG. 7(a), when the temporary impedance (Z1, θ1), the temporary impedance (Z2, θ2), and the temporary impedance (Z3, θ3) are added together, the vector sum value (Zb, θb) is obtained. Become. The phase θb of the vector sum value (Zb, θb) is the phase difference with respect to the temporary signal Tem1 when the temporary signal Tem1 is used as a reference (zero).

On the other hand, as shown in FIG. 7(b), the impedance (Za, θa) of the assembled battery 10 is based on the first reference signal Ref1 (=AC signal) (zero). That is, the phase θa of the impedance of the assembled battery 10 is a phase difference with respect to the first reference signal Ref1 when the first reference signal Ref1 is used as a reference (zero).

As described above, the amplitude Is and frequency fs of the first reference signal Ref1, temporary signal Tem1, and AC signal are the same. Therefore, the absolute value Za of the impedance of the assembled battery 10 is the same as the absolute value Zb of the vector sum value. Therefore, the impedance (Za, θa) of the assembled battery 10, the vector sum value (Zb, θb), the first reference signal Ref1, and the temporary signal Tem1 can be illustrated as shown in FIG.

According to FIG. 7, as shown in equation (3), the phase difference (θt−θs) between the temporary signal Tem1 and the first reference signal Ref1 is equal to the phase θb of the vector sum and the phase of the impedance of the assembled battery 10. It can be seen that this corresponds to the phase difference (θa−θb) with respect to θa. The phase θb of the vector summation value can be calculated based on the temporary impedances (Z1, θ1), (Z2, θ2), (Z3, θ3) of each battery cell 11i and the absolute value Zb of the vector summation value. Since the absolute value Zb of the vector sum is the same as the absolute value Za of the impedance of the assembled battery 10, it can be calculated as shown in equation (4).

Then, as shown in formula (5), the phase θi of the temporary impedance of each battery cell 11i is corrected based on the phase difference (θa−θb) between the vector sum value and the impedance of the assembled battery 10, and the first It is possible to calculate the true impedance (Zsi, θsi) of each battery cell 11i using the reference signal Ref1 as a reference. Note that since the absolute value Zsi of the true impedance is the same value as the absolute value Zi of the temporary impedance, it can be calculated based on the absolute value Zi of the temporary impedance.

Here, we return to the explanation of the correction process. After acquiring the temporary impedance (Zi, θi) of each battery cell 11i (step S306), the first control device 22 then calculates the phase θb of the vector sum of the acquired temporary impedances (Zi, θi) using the formula ( Calculate using the same method as 4) (step S307). That is, the first control device 22 calculates the phase θb of the vector sum value based on the impedance (Zi, θi) of each battery cell 11i and the absolute value Za of the impedance of the assembled battery 10.

Next, the first control device 22 calculates the phase difference (θt−θs) between the temporary signal Tem1 and the first reference signal Ref1, that is, the difference between the vector sum value and the impedance of the assembled battery 10, based on equation (3). A phase difference (θa−θb) is calculated (step S308). Then, the first control device 22 corrects the phase shift of each provisional impedance based on formula (5), and calculates the true impedance (Zsi, θsi) of each battery cell 11i with respect to the first reference signal Ref1 ( Step S308). Then, the correction process ends.

Thereafter, the state of each battery cell 11i is monitored based on the calculated true impedance (Zsi, θsi) of each battery cell 11i. For example, the first control device 22 outputs the true impedance (Zsi, θsi) to an external device, and the state of each battery cell 11i is monitored by the external device. Note that the state of each battery cell 11i may be monitored by the first control device 22 or the second control device 31.

As described above, this embodiment has the following effects.

(1) The phase θs of the AC signal is time-related information (timing-related information) and can only be sent as an analog signal (analog information). Therefore, when the wiring between the current control device 20 and the battery monitoring device 30, that is, the wiring between the first control device 22 and the second impedance detection device 32, is long, information regarding the phase θs of the AC signal is Even if it is transmitted, a phase shift will occur due to communication delay. Furthermore, in the case of the assembled battery 10 for use in a vehicle, since auxiliary equipment is connected, noise due to the auxiliary equipment is often mixed in. For this reason, it is also difficult to measure the current flowing through the assembled battery 10 and identify the AC signal input from the current application device 21.

Therefore, the battery measurement system 100 described above first includes a first impedance detection device 23 that detects the impedance (Za, θa) of the assembled battery 10. Also, a second control device 31 inputs a digital signal (digital information) regarding the amplitude Is and frequency fs of the AC signal and determines the temporary signal Tem1 based on them, and the temporary signal Tem1 and the voltage fluctuation Vi of each battery cell 11i. A second impedance detection device 32 was provided to detect the temporary impedance (Zi, θi) of each battery cell 11i based on the following.

The first control device 22 then compares the vector summation value (Zb, θb) obtained by summing up the temporary impedances (Zi, θi) of each battery cell 11i with the impedance (Za, θa) of the assembled battery 10. The phase difference (θt−θs) between the AC signal (=first reference signal Ref1) and the temporary signal Tem1 is specified, and based on the phase difference, the phase θi of the temporary impedance is corrected to obtain the phase of the true impedance. It has a function as a correction section that calculates θsi. This makes it possible to accurately detect the true impedance (Zsi, θsi) of each battery cell 11i.

(2) The current control device 20 includes a first control device 22, a current application device 21, and a first impedance detection device 23. This allows the first control device 22, the current application device 21, and the first impedance detection device 23 to form a closed path within the current control device 20, and the first control device 22 and the current application device 21 It is possible to suppress noise from being mixed between the first impedance detection device 23 and the first impedance detection device 23.

On the other hand, the battery monitoring device 30 includes a second control device 31 and a second impedance detection device 32. The second control device 31 and the second impedance detection device 32 can be connected in a closed path within the battery monitoring device 30, which prevents noise from entering between the second control device 31 and the second impedance detection device 32. can be suppressed. Note that since the amplitude Is and the frequency fs are input and output as digital information, the accuracy of information transmission does not deteriorate even if the wiring between the current control device 20 and the battery monitoring device 30 becomes long.

(3) The second sine wave generation circuit 33 is connected to all the second lock-in amplifiers 34i, and can synchronize and output the temporary signal Tem1 to each second lock-in amplifier 34i. Therefore, when detecting the temporary impedance (Zi, θi) of each battery cell 11i, it is possible to suppress the occurrence of a phase difference between the temporary impedances (Zi, θi) with respect to the temporary signal Tem1 to be used as a reference. be able to. This makes it possible to improve the detection accuracy of true impedance (Zsi, θsi).

(Second embodiment)
The battery measurement system 100 of the first embodiment may partially change its configuration. Here, a battery measurement system 100 according to a second embodiment will be described. In this second embodiment, the basic configuration will be explained using the first embodiment as an example.

In the battery measurement system 100 of the second embodiment, as shown in FIG. 8, a second impedance detection device 32i (i=1, 2, 3, 4, 5, 6 ) is provided. Signals are input to each second impedance detection device 32i from a second sine wave generation circuit 33i (i=1, 2, 3, 4, 5, 6) and a second sine wave generation circuit 33i, respectively. A second lock-in amplifier 34i is provided.

Each second impedance detection device 32i is connected to the second control device 31 so that instructions for the amplitude Is and frequency fs of the temporary signal Tem1 can be input. Further, the second control device 31 is configured to output a synchronization signal that controls the phase of the temporary signal Tem1 in order to align the output start timing of the temporary signal Tem1. As shown in FIG. 9, the synchronization signal is output at a predetermined timing after the amplitude Is and frequency fs of the temporary signal Tem1 are specified.

The second impedance detection devices 32i are arranged so as to be connected in series on the electrical path through which this synchronization signal is transmitted. More specifically, the second impedance detection devices 32i are arranged in one row, and are connected in series by connecting adjacent second impedance detection devices 32i to each other.

The synchronization signal output from the second control device 31 is input to the second impedance detection device 326 on the first end side among the second impedance detection devices 32i connected in series. When the second impedance detection device 326 on the first end side receives the synchronization signal, it outputs (transmits) it to the adjacent second impedance detection device 325. Similarly, when the second impedance detection device 32i on the first end side receives a synchronization signal, it outputs (transmits) it to the adjacent second impedance detection device 32(i-1) on the second end side. As a result, the synchronization signal is sequentially transmitted from the second impedance detection device 326 on the first end side to the second impedance detection device 321 on the second end side.

When each second impedance detection device 32i receives the synchronization signal, the second sine wave generation circuit 33i generates a temporary signal Tem1 and outputs it to the second lock-in amplifier 34i, as shown in FIG. Similarly to the first embodiment, the second lock-in amplifier 34i detects the temporary impedance (Zi, θi) based on the temporary signal Tem1 and the voltage fluctuation Vi of each battery cell 11i, and transmits the detected impedance to the second control device 31. Output. As described above, it is possible to arbitrarily change the configuration of the second sine wave generation circuit 33i.

(Third embodiment)
The battery measurement system 100 of the above embodiment may partially change its configuration. Here, a battery measurement system 100 according to a third embodiment will be described. In this third embodiment, the basic configuration will be explained using the second embodiment as an example.

FIG. 10 is an enlarged view of the second impedance detection device 32i of the battery monitoring device 30. As shown in FIG. 10, in the battery monitoring device 30 of the battery measurement system 100 of the third embodiment, as in the second embodiment, a second impedance detection device 32i (as a second detection section) is detected for each battery cell 11i. i=1, 2, 3, 4, 5, 6).

Here, when each second impedance detection device 32i transmits a synchronization signal to an adjacent second impedance detection device 32i, a slight shift may occur in the input/output timing of the synchronization signal due to a transmission delay or the like. If this shift is left as is, there is a possibility that a phase shift will occur in the temporary signal Tem1 between the respective second impedance detection devices 32i.

Therefore, in the battery measurement system 100 of the third embodiment, the phases of the temporary signals Tem1 are aligned by processing as follows. This will be explained in detail below. Note that it is assumed that the transmission delay time td between adjacent second impedance detection devices 32i is the same.

As shown in FIG. 11, when the first synchronization signal is output from the second control device 31, the second impedance detection device 326 on the first end side outputs the second synchronization signal on the second end side, similarly to the second embodiment. The first synchronization signal is sequentially transmitted up to the impedance detection device 321. When the second impedance detection device 321 on the second end side receives the first synchronization signal, it outputs the second synchronization signal to the adjacent second impedance detection device 322 after a predetermined standby time ta1 has elapsed. When the second impedance detection device 322 receives the second synchronization signal, it outputs the second synchronization signal to the second impedance detection device 323 on the adjacent first end side. Thereafter, in the same manner, the second synchronization signal is sequentially transmitted from the second impedance detection device 321 on the second end side to the second impedance detection device 326 on the first end side.

Then, each second impedance detection device 32i subtracts the input/output timing of the first synchronization signal from the input/output timing of the second synchronization signal. As a result, each second impedance detection device 32i calculates the time tai from outputting the first synchronization signal to the second end until the second synchronization signal returns from the second end, which is the starting point of the round trip. Calculate each.

Next, each second impedance detection device 32i determines the waiting time tbi according to equation (6). Note that in the second impedance detection device 326, the time ta6 from inputting the first synchronization signal to outputting (replying) the second synchronization signal, and the current waveform after outputting (replying) the second synchronization signal, are determined in advance. It is assumed that the waiting time tb6 until the trigger is generated is predetermined and stored in each second impedance detection device 32i.

Then, each second impedance detection device 32i generates a current waveform trigger after a waiting time tbi has elapsed since inputting the second synchronization signal, and using this as an opportunity, the second sine wave generation circuit 33i generates a temporary signal Tem1. Generate and output. As a result, detection of temporary impedance (Zi, θi) starts.

As a result, the transmission delay time td is corrected in each second impedance detection device 32i, and the temporary signal Tem1 is simultaneously outputted, so that the phase of the temporary signal Tem1 does not shift between the second impedance detection devices 32i. can do. Therefore, the detection accuracy of temporary impedance (Zi, θi) can be improved.

(Modified example of the above embodiment)
- In the above embodiment, a part of the configuration of the battery measurement system 100 may be changed as shown in FIGS. 12 to 14. That is, in the battery measurement system 100 of FIG. 12, a plurality of second impedance detection devices 32a and 32b are provided to monitor a plurality of (three in FIG. 12) battery cells 11i. Each second impedance detection device 32a, 32b is provided with a second lock-in amplifier 34i for each battery cell 11i. Note that each second impedance detection device 32a, 32b is provided with one second sine wave generation circuit 33a, 33b, respectively. Each second sine wave generation circuit 33a, 33b is configured to output a temporary signal Tem1 to the plurality of second lock-in amplifiers 34i. Note that, in order to synchronize the phase of the temporary signal Tem1, a synchronization signal is input and output similarly to the second embodiment and the third embodiment.

Moreover, in the battery measurement system 100 of FIG. 13, a plurality of second impedance detection devices 32a and 32b are provided to monitor a plurality of (three in FIG. 13) battery cells 11i connected in series. In the battery measurement system 100 of FIG. 13, the second impedance detection device 32a monitors a cell module composed of a plurality of battery cells 111 to 113 connected in series, and the temporary impedance ( Z10, θ10) is detected. Further, the second impedance detection device 32b uses a cell module composed of a plurality of battery cells 114 to 116 connected in series as one monitoring target, and detects the temporary impedance (Z20, θ20) of the cell module. For this reason, each second impedance detection device 32a, 32b is provided with a second lock-in amplifier 34a, 34b for each cell module.

Each second impedance detection device 32a, 32b is provided with one second sine wave generation circuit 33a, 33b, respectively. Each second sine wave generation circuit 33a, 33b is configured to output a temporary signal Tem1 to the second lock-in amplifier 34a, 34b, respectively. Note that, in order to synchronize the phase of the temporary signal Tem1, a synchronization signal is input and output similarly to the second embodiment and the third embodiment.

In the battery measurement system 100 of FIG. 13, the phase shift is corrected similarly to the above embodiment, and the true impedance of the cell module is finally calculated.

In the battery measurement system 100 of FIG. 14, one second impedance detection device 32 is provided. This second impedance detection device 32 is provided with a plurality of second lock-in amplifiers 3412, 343, 344, and 3456. Each second lock-in amplifier 3412, 343, 344, 3456 is configured to monitor one or more battery cells 11i. Specifically, the second lock-in amplifiers 3412, 3456 monitor a cell module composed of a plurality of battery cells 111, 112, 115, 116, and calculate the temporary impedance (Z12, θ12) (Z56) of each cell module. , θ56). On the other hand, the second lock-in amplifiers 343 and 344 monitor one battery cell 113 and 114, and detect temporary impedances (Z3, θ3) (Z4, θ4) of the battery cells 113 and 114, respectively.

In the battery measurement system 100 of FIG. 14, the phase shift is corrected in the same manner as in the above embodiment, and finally the true impedance of the battery cells 113, 114, the true impedance of the cell module composed of the battery cells 111, 112, The true impedance of the cell module composed of the battery cells 115 and 116 will be calculated.

Note that one second lock-in amplifier 343, 344 is configured to detect the temporary impedance of each of the battery cells 113, 114 whose average temperature tends to be high among the battery cells 11i. On the other hand, the other second lock-in amplifiers 3412 and 3456 monitor the plurality of battery cells 11i whose average temperature tends to be low.

That is, the battery measurement system 100 of FIG. 14 is configured to accurately detect the temporary impedance of the battery cells 113 and 114, which tend to have high average temperatures among the battery cells 11i. On the other hand, one second lock-in amplifier 3412, 3456 monitors multiple battery cells 11i while allowing the accuracy to deteriorate for other battery cells 11i whose average temperature tends to be low. It is said that Thereby, manufacturing costs can be suppressed.

- In the above embodiment, a part of the configuration of the battery measurement system 100 may be changed as shown in FIGS. 15 and 16. That is, in the battery measurement system 100 of FIG. 15, a plurality of first impedance detection devices 23a and 23b are provided. Each of the first impedance detection devices 23a and 23b is configured to detect the impedance of a cell module composed of a plurality of battery cells 11i connected in series. The impedance (Za, θa) of the battery pack 10 can be determined by adding up the impedances of the cell modules detected by the first impedance detection devices 23a and 23b.

In the battery measurement system 100 of FIG. 16, a plurality of first impedance detection devices 23a and 23b are provided, as in FIG. 15. Note that the impedance (Za, θa) of the assembled battery 10 can be determined by summing the impedances of the cell modules detected by each of the first impedance detection devices 23a and 23b.

In the second impedance detection device 32 of FIG. 16, a plurality of second lock-in amplifiers 3412, 3434, and 3456 are provided. Each of the second lock-in amplifiers 3412, 3434, and 3456 is configured to monitor a cell module composed of a plurality of battery cells 11i. Then, the tentative impedances (Z12, θ12) (Z34, θ34) (Z56, θ56) of the cell modules are detected, respectively.

In the battery measurement system 100 of FIG. 15, the phase shift is corrected as in the above embodiment, and the true impedance of the cell module composed of battery cells 111 and 112 and the cell module composed of battery cells 113 and 114 are finally measured. The true impedance of the module and the true impedance of the cell module composed of the battery cells 115 and 116 are calculated.

- In the above embodiments and modifications, the alternating current signal is not limited to a sine wave current, but may be changed to any alternating current. For example, a square wave current may be used.

- In the above embodiments and modified examples, the first control device 22 has a function as a correction section that corrects the phase difference, but the second control device 31 or other external device has a function as a correction section. It's okay.

- In the above embodiment, impedance was detected for each battery cell 11i, but the unit of battery cell 11i in which impedance is detected may be changed arbitrarily. For example, the battery cells 11i constituting the assembled battery 10 may be divided in advance into cell blocks each consisting of a plurality of battery cells 11i connected in series, and the impedance may be detected for each cell block.

- In the above embodiment and modification, as shown in FIG. 17, the current control device 20 may be provided with a current sensor 90 that detects an AC signal flowing through the assembled battery 10. Then, the first control device 22 may acquire the amplitude Is of the AC signal detected by the current sensor 90 and use it as feedback information when instructing the AC signal. Alternatively, it may be output to the first impedance detection device 23. Thereby, accuracy can be further improved.

DESCRIPTION OF SYMBOLS 10... Assembled battery, 21... Current application device, 22... First control device, 23, 23a, 23b... First impedance detection device, 30... Battery monitoring device, 32, 32a, 32b, 321-326... Second impedance detection Apparatus, 90...Current sensor, 100...Battery measurement system, 111-116...Battery cell.

Claims (7)

In a battery measurement system (100) that measures the state of each battery cell of an assembled battery (10) in which a plurality of battery cells (111 to 116) are connected in series,
The battery cells constituting the assembled battery are divided in advance into cell blocks each consisting of one or more battery cells connected in series,
a first control unit (22) that instructs a predetermined AC signal;
a signal application unit (21) that applies the AC signal to the assembled battery based on instructions from the first control unit;
a reference signal corresponding to the AC signal determined based on at least one of information from the first control unit and a measurement result of the current sensor (90), and when the AC signal is applied to the assembled battery; a first detection unit (23, 23a, 23b) that detects the impedance of the assembled battery based on the voltage fluctuation of the assembled battery measured in
based on a temporary signal related to the AC signal determined based on information from the first control unit and a voltage fluctuation of the cell block measured while the AC signal is being applied to the assembled battery. a second detection unit (32, 321 to 326, 32a, 32b) that detects the impedance of each cell block;
By comparing a vector sum value obtained by summing up the impedances of the cell blocks detected by the second detection section and a vector value as the impedance of the assembled battery detected by the first detection section, A battery measurement system comprising: a correction unit (22) that specifies a phase difference between a reference signal and the temporary signal, and corrects a phase of impedance of each cell block based on the phase difference. a current control device (20) including at least the first control section, the signal application section, and the first detection section;
a second control unit that receives digital information regarding the amplitude and frequency of the AC signal from the first control unit of the current control device and determines the provisional signal based on the digital information; and the second detection unit. The battery measurement system according to claim 1, comprising at least a battery monitoring device (30). The second detection unit includes:
a second signal generation unit (33) that generates the temporary signal having the same amplitude and frequency as the AC signal;
measuring the temporary signal generated by the second signal generation unit and the voltage fluctuation of each of the cell blocks, and determining the absolute value and phase of the impedance of each of the cell blocks based on the measured voltage fluctuation of each of the cell blocks; a second calculation unit (341 to 346) that calculates and detects the impedance of each cell block;
A plurality of the second calculation units are provided for each one or more of the cell blocks to be monitored, while the second signal generation unit is connected to all the second calculation units, and the second signal generation unit is connected to all the second calculation units, and The battery measurement system according to claim 1 or 2, wherein the temporary signal is output to each second calculation section. A plurality of the second detection units are provided for each one or more of the cell blocks to be monitored,
Each of the second detection units is
a second signal generation unit (331 to 336) that generates the temporary signal having the same amplitude and frequency as the AC signal;
The temporary signal generated by the second signal generation unit and the voltage fluctuation of the cell block to be monitored are measured, and the absolute value and phase of the impedance of the cell block are determined based on the measured voltage fluctuation of the cell block. and a second calculation unit (341 to 346) that calculates the impedance of the cell block,
The battery measurement system according to claim 1 or 2, wherein each of the second signal generation units generates and outputs the temporary signal in synchronization based on a timing at which a synchronization signal is input. The second detection units are connected in series and are configured such that a synchronization signal is input from the second detection unit at the first end, and the input synchronization signal is transmitted to the second detection unit at the first end in the form of relay transmission. It is configured to reciprocate between the detection section and the second detection section at the second end,
Each of the second signal generation units generates a synchronization signal between each of the second detection units based on the input/output timing of the synchronization signal transmitted from the first end side and the synchronization signal transmitted from the second end side. 5. The battery measurement system according to claim 4, wherein the temporary signal is generated and output in synchronization between the respective second detection units by correcting a transmission delay. The second calculation unit calculates the real part of the voltage fluctuation based on a value obtained by multiplying the temporary signal output by the second signal generation unit and the voltage fluctuation of the cell block, and calculates the real part of the voltage fluctuation, and An imaginary part of the voltage fluctuation is calculated based on a value obtained by multiplying a signal whose phase is shifted by the voltage fluctuation of the cell block, and an impedance is calculated based on the imaginary part of the voltage fluctuation. The battery measurement system according to any one of these items. The first detection unit includes:
a first signal generation unit that generates the reference signal having the same amplitude, frequency, and phase as the AC signal;
Calculating the absolute value and phase of the impedance of the assembled battery based on the reference signal generated by the first signal generation unit and the voltage fluctuation of the assembled battery when the alternating current signal is applied, and calculating the impedance of the assembled battery. a first calculation unit that detects;
The first calculation unit calculates the real part of the voltage fluctuation based on a value obtained by multiplying the reference signal output by the first signal generation unit and the voltage fluctuation of the assembled battery, and calculates the real part of the voltage fluctuation, An imaginary part of the voltage fluctuation is calculated based on a value obtained by multiplying the phase-shifted signal by the voltage fluctuation of the assembled battery, and an impedance is calculated based on the imaginary part of the voltage fluctuation. The battery measurement system according to any one of these items.

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