Cell module inspection device

Abstract

Provided is a cell module inspection device that makes it possible to easily inspect the degree of deterioration of a cell module. This cell module inspection device comprises: an impedance detection circuit that detects a measurement current which is applied to a plurality of cell modules connected in series, that detects a response voltage which occurs at each terminal of the plurality of cell modules, and that calculates the internal impedance of each of the plurality of cell modules on the basis of the measurement current and the response voltage; and a connection polarity switching circuit that is disposed between the impedance detection circuit and the terminal of each of the plurality of cell modules. Even if a cell module is reverse-connected to the connection polarity switching circuit, the connection polarity switching circuit uses the stored power of the cell module to automatically switch the output polarity of the connection polarity switching circuit to the same polarity as in the case of normal connection. The output polarity of the connection polarity switching circuit is set by combining, per cell module, inversion and non-inversion in the direction of the series connection.

Description

Cell module inspection equipment

[0001] The present invention relates to an inspection device for a cell module.

[0002] Patent Document 1 discloses a rechargeable battery tester for cordless telephones that improves operability by using a non-polarizing circuit to always keep the polarity constant regardless of how the device under test is connected.

[0003] Japanese Unexamined Patent Publication No. 7-72226

[0004] For example, a cell module installed in a vehicle such as an EV (electric vehicle) may be removed from the vehicle and its deterioration inspected. This inspection requires matching the polarity of the terminals of the cell module being inspected (hereinafter also referred to as the test cell module) with the polarity of the terminals of the inspection device, which is time-consuming and labor-intensive. Furthermore, the test cell module is very heavy because it contains multiple high-capacity cells. Therefore, lifting and shifting the test cell module during the polarity adjustment process requires even more effort.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a cell module inspection device that can easily inspect the degree of deterioration of a cell module.

[0006] A cell module inspection device according to one aspect of the present invention includes an impedance detection circuit that detects a measurement current applied to a plurality of cell modules connected in series and a response voltage appearing at each terminal of the plurality of cell modules, and calculates the internal impedance of each of the plurality of cell modules from the measurement current and the response voltage, and a connection polarity switching circuit disposed between each terminal of the plurality of cell modules and the impedance detection circuit. Even if a cell module is connected in a polarity opposite to that preset in the connection polarity switching circuit, the connection polarity switching circuit automatically switches the output polarity of the connection polarity switching circuit to the same polarity as in the case of a positive connection, using the stored power of the cell module. The output polarity of the connection polarity switching circuit is set for each cell module to a combination of inversion and non-inversion of the series connection direction.

[0007] According to one aspect of the present invention, the deterioration level of a cell module can be easily inspected.

[0008] FIG. 1 is a block diagram showing an example of the configuration of a cell module degradation inspection device according to a first embodiment of the present invention. FIG. 2A is a circuit diagram showing an example of the configuration (forward connection) of a connection polarity switching circuit with a non-inverting output specification. FIG. 2B is a circuit diagram showing an example of the configuration (for reverse connection) of a connection polarity switching circuit with a non-inverting output specification. FIG. 3A is a circuit diagram showing an example of the configuration (for reverse connection) of a connection polarity switching circuit with an inverting output specification. FIG. 3B is a circuit diagram showing an example of the configuration (for forward connection) of a connection polarity switching circuit with an inverting output specification. FIG. 4 is a diagram showing an example of a series connection (even number) via a polarity switching circuit according to the first embodiment of the present invention. FIG. 5 is a diagram showing an example of a series connection (odd number) via a polarity switching circuit according to the first embodiment of the present invention. FIG. 6 is a diagram showing an example of a series connection via a polarity switching circuit according to a comparative example of the present invention. FIG. 7 is a block diagram showing an example of the overall configuration of a cell module degradation inspection device according to the first embodiment of the present invention. FIG. 8 is a block diagram showing a modified example of the cell module degradation inspection device according to the first embodiment of the present invention. FIG. 9 is a block diagram showing an example of the configuration of a main part of a cell module degradation inspection device according to a second embodiment of the present invention. FIG. 10 is a diagram showing a modified example of the cell module deterioration inspection device according to the second embodiment of the present invention.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings referred to in the following description, the same or similar parts are designated by the same or similar reference numerals.

[0010] 1, a cell module degradation inspection device 1 includes an inspection device-side terminal INS connected to a cell module (i.e., a test cell module) MD to be inspected, a connection polarity switching circuit 2, and an impedance detection circuit 3 connected to the test cell module MD via the connection polarity switching circuit 2, detection voltage lines LP, LN, and LM, and measurement current line LIm. The connection polarity switching circuit 2 is disposed between the inspection device-side terminal INS and the impedance detection circuit 3 and is connected to the inspection device-side terminal INS and the impedance detection circuit 3. The connection polarity switching circuit 2 is connected to the test cell module MD via the inspection device-side terminal INS. Note that FIG. 1 also shows a test cell module MD-1, a connection polarity switching circuit 21 with a non-inverting output that connects to the test cell module MD-1 via the inspection device-side terminal INS-1, a test cell module MD-2, and a connection polarity switching circuit 22 with an inverting output that connects to the test cell module MD-2 via the inspection device-side terminal INS-2. 1 shows an example in which two test cell modules MD are simultaneously diagnosed for deterioration (cell impedance measurement), but this is merely one example. As shown in Fig. 4 described later, the deterioration test device 1 may be configured to simultaneously diagnose six test cell modules MD for deterioration, or as shown in Fig. 5 described later, it may be configured to simultaneously diagnose five test cell modules MD for deterioration. Also, in Fig. 1 and Figs. 4 and 5 described later, sub-numbers -1, -2, -3, ... are added to the symbol MD to individually identify the multiple test cell modules MD, but these sub-numbers are omitted when identification is not necessary.

[0011] (Test Cell Module) As shown in Figure 1, each of the multiple test cell modules MD (e.g., test cell modules MD-1, MD-2, ...) has, for example, two battery cells CE connected in series. The output voltage of each battery cell CE is a maximum of 4.2 V, and the output voltage of the test cell module MD having two battery cells CE is a maximum of 8.4 V. The potential of the positive terminal P (hereinafter referred to as terminal P) is 8.4 V, the potential of the negative terminal N (hereinafter referred to as terminal N) is 0 V, and the potential of the intermediate terminal M (hereinafter referred to as terminal M) connected midway between terminals P and N (i.e., the connection between the two battery cells CE connected in series) is 4.2 V. Note that the potentials of terminals P and N may vary from the above-mentioned values ​​depending on the degree of deterioration of the battery cells CE, etc.

[0012] (Inspection Equipment Side Terminals) The inspection equipment side terminals INS (INS-1, INS-2, ...) are terminals that are connected to the test cell modules MD (MD-1, MD-2, ...) in a 1:1 relationship. The inspection equipment side terminal INS-1 is connected to the test cell module MD-1, and the inspection equipment side terminal INS-2 is connected to the test cell module MD-2. In Figure 1 and Figures 8 and 9 described below, sub-numbers -1 and -2 are added to the symbol INS to individually identify the multiple inspection equipment side terminals INS, but these sub-numbers are omitted when identification is not necessary. The inspection equipment side terminal INS has a positive terminal P (terminal P), a negative terminal N (terminal N), and an intermediate terminal M (terminal M).

[0013] When the test cell module MD is connected to the inspection equipment terminal INS in a preset polarity (i.e., a predetermined polarity), terminal P of the test cell module MD is connected to terminal P of the inspection equipment terminal INS, terminal N of the test cell module MD is connected to terminal N of the inspection equipment terminal INS, and terminal M of the test cell module MD is connected to terminal M of the inspection equipment terminal INS. On the other hand, when the test cell module MD is connected to the inspection equipment terminal INS in a polarity opposite to the predetermined polarity, terminal N of the test cell module MD is connected to terminal P of the inspection equipment terminal INS, and terminal P of the test cell module MD is connected to terminal N of the inspection equipment terminal INS. Figure 1 and Figures 8 and 9 described below illustrate a case where the test cell module MD1 is connected to the inspection equipment terminal INS-1 in a predetermined polarity, and the test cell module MD2 is connected to the inspection equipment terminal INS-2 in a polarity opposite to the predetermined polarity.

[0014] 1, the connection polarity switching circuit 2 is arranged between terminals P and N of the cell module MD and the input operational amplifiers INA1 and INA2 of the impedance detection circuit 3. In this specification, connection of the test cell module MD to the connection polarity switching circuit 2 via the inspection device side terminal INS in accordance with a polarity that is preset (i.e., a predetermined polarity) is referred to as a positive connection, and connection in the opposite direction to the predetermined polarity is referred to as a reverse connection.

[0015] (1) Connection polarity switching circuit with non-inverting output Fig. 2A shows the case of a positive connection, and Fig. 2B shows the case of a reverse connection. As shown in Fig. 2A and Fig. 2B, the connection polarity switching circuit 21 with a non-inverting output includes a diode D1, a relay drive coil 11 connected to the anode of the diode D1, a current limiting resistor 12 connected in series with the relay drive coil 11, and double-pole double-throw polarity switching switches 13A and 13B (an example of the "switch" of the present invention) operated by the relay drive coil 11.

[0016] As shown in Figure 2A, in the case of positive connection, the cathode of diode D1 is connected to terminal P of the test cell module MD, and the anode of diode D1 is connected to terminal N of the test cell module MD via current-limiting resistor 12 and relay drive coil 11. In the positive connection, a reverse voltage is applied from the test cell module MD to diode D1, and no forward current Is flows through diode D1. Therefore, no forward current Is flows through relay drive coil 11, and double-pole double-throw polarity changeover switches 13A and 13B are turned off. The voltage signals of terminals P and N of the test cell module MD are output from the output terminals of connection polarity changeover circuit 21 without inverting the polarity (without swapping the polarity in Figure 2A) and input to input operational amplifiers INA1 and INA2 of the impedance detection circuit 3, respectively (non-inverted polarity).

[0017] On the other hand, as shown in Figure 2B, in the case of reverse connection, the cathode of diode D1 is connected to terminal N of the test cell module MD, and the anode of diode D1 is connected to terminal P of the test cell module MD via current-limiting resistor 12 and relay drive coil 11. In the reverse connection, a forward voltage is applied from the test cell module MD to diode D1, causing a forward current Is to flow through diode D1. As a result, a forward current Is also flows through relay drive coil 11, turning on double-pole double-throw polarity changeover switches 13A and 13B. The voltage signals of terminals P and N of the test cell module MD are output from the output terminals of connection polarity changeover circuit 21 with their polarities reversed (the polarities are reversed in Figure 2B) and input to the input operational amplifiers INA1 and INA2 of the impedance detection circuit 3, respectively (polarity reversed).

[0018] In this way, the non-inverting output connection polarity switching circuit 21 inverts the polarity of the test cell module MD and outputs a voltage signal to the input operational amplifiers INA1 and INA2 in the case of a reverse connection. Depending on the direction of diode D1 and the wiring configuration that turns on polarity switching switches 13A and 13B, the output polarity of the connection polarity switching circuit 21 can be aligned to a predetermined polarity (i.e., the output polarity from switch 13A matches the polarity of terminal P, and the output polarity from switch 13B matches the polarity of terminal N) not only when the test cell module MD is connected to the connection polarity switching circuit 21 in a forward direction but also when the test cell module MD is connected in a reverse direction. Regardless of whether the input polarity to the connection polarity switching circuit 21 is forward or reverse, a voltage of the same polarity appears at the output terminal of the connection polarity switching circuit 21 (non-polarized). Regardless of whether the test cell module MD is connected forward or reverse to the connection polarity switching circuit 21, the output polarity of the connection polarity switching circuit 21 is non-inverted relative to the serial connection direction of the test cell module MD. The polarity of the double-pole double-throw is automatically switched reliably by the potential of the diode D1 and the test cell module MD. This eliminates the need for complicated circuits such as polarity sensors or microcomputer-based switching command systems, and also makes it possible to avoid problems such as false detection and command malfunctions.

[0019] (2) Reversed Output Connection Polarity Switching Circuit Fig. 3A shows the case of reverse connection, and Fig. 3B shows the case of forward connection. As shown in Fig. 3A and Fig. 3B, the reversed output connection polarity switching circuit 22 includes a diode D2, a relay drive coil 11 connected to the anode of the diode D2, a current limiting resistor 12 connected in series with the relay drive coil 11, and double-pole, double-throw polarity switching switches 13A and 13B operated by the relay drive coil 11.

[0020] As shown in Figure 3A, in the case of reverse connection, the anode of diode D2 is connected to terminal P of the test cell module MD, and the cathode of diode D2 is connected to terminal N of the test cell module MD via current-limiting resistor 12 and relay drive coil 11. In the reverse connection, a forward voltage is applied from the test cell module MD to diode D2, causing a forward current Is to flow through diode D2. As a result, a forward current Is also flows through relay drive coil 11, turning on double-pole double-throw polarity changeover switches 13A and 13B operated by relay drive coil 11. The voltage signals of terminals P and N of the test cell module MD are output from the output terminals of connection polarity changeover circuit 22 with their polarities reversed (the polarities are reversed in Figure 3A) and input to input operational amplifiers INA1 and INA2 of the impedance detection circuit 3, respectively (polarity reversed).

[0021] On the other hand, as shown in Figure 3B, in the case of a positive connection, the anode of diode D2 is connected to terminal N of the test cell module MD, and the cathode of diode D2 is connected to terminal P of the test cell module MD via current-limiting resistor 12 and relay drive coil 11. In the positive connection, a reverse voltage is applied from the test cell module MD to diode D2, and no forward current Is flows through diode D2. As a result, no forward current Is flows through relay drive coil 11, and the double-pole double-throw polarity changeover switches 13A and 13B operated by relay drive coil 11 are turned OFF. The voltage signals of terminals P and N of the test cell module MD are output from the output terminals of the connection polarity changeover circuit 22 without inverting the polarity (without swapping the polarity in Figure 3B) and are input to the input operational amplifiers INA1 and INA2 of the impedance detection circuit 3, respectively (non-inverted polarity).

[0022] In this way, the inverted-output connection polarity switching circuit 22 outputs a voltage signal to the input operational amplifiers INA1 and INA2 without inverting the polarity of the test cell module MD in the case of a forward connection. Depending on the direction of diode D2 and the wiring configuration that turns on the polarity switching switches 13A and 13B, the output polarity of the connection polarity switching circuit 22 can be aligned to a predetermined polarity (i.e., the output polarity from switch 13A matches the polarity of terminal N, and the output polarity from switch 13B matches the polarity of terminal P) not only when the test cell module MD is connected to the connection polarity switching circuit 22 in the forward direction but also when the test cell module MD is connected in the reverse direction. Regardless of whether the input polarity to the connection polarity switching circuit 22 is forward or reverse, a voltage of the same polarity appears at the output terminal of the connection polarity switching circuit 22 (non-polarized). Regardless of whether the test cell module MD is connected forward or reverse to the connection polarity switching circuit 22, the output polarity of the connection polarity switching circuit 22 is inverted relative to the direction of the series connection of the test cell module MD. The polarity switching of the double-pole double-throw is automatically and reliably performed by the potential of the diode D2 and the test cell module MD. As a result, the connection polarity switching circuit 22 does not require a complex circuit like the above-mentioned switching command method, and it is also possible to avoid problems such as erroneous detection and command malfunction.

[0023] (Conducting circuit including diode, relay drive coil, etc.) The conducting circuit including the diode (or diode D2), relay drive coil 11, and current-limiting resistor 12 is connected in parallel with the test cell module MD. Because of this relationship, the AC current Im (an example of the "measurement current" in this specification) during impedance measurement flows not only through the test cell module MD but also through the diode D1 (or diode D2), relay drive coil 11, and current-limiting resistor 12, which strictly speaking constitutes a measurement error. However, particularly in cases where the internal impedance of the test cell module MD is extremely low (1 mΩ range), such as in a vehicle drive cell, the impedance of the relay drive coil 11 and current-limiting resistor 12 is excessively high (several hundred Ω), so almost all of the measuring AC current Im flows through the test cell module MD. Therefore, the AC current Im flowing through the conducting circuit including the diode D1 (or diode D2), relay drive coil 11, and current-limiting resistor 12 is practically negligible (i.e., it can be ignored as a measurement error).

[0024] (Impedance Detection Circuit) The impedance detection circuit 3 comprises a measurement AC current generating circuit 31 for applying a measurement AC current Im to the test cell module MD, and input operational amplifiers INA1 and INA2 to which voltage signals are input from the test cell module MD via detection voltage lines LP, LN, and LM. The detection voltage line LP connects terminal P of the test cell module MD to the non-inverting input terminal (hereinafter referred to as the + terminal) of the input operational amplifier INA2. The detection voltage line LN connects terminal N of the test cell module MD to the inverting input terminal (hereinafter referred to as the - terminal) of the input operational amplifier INA1. The detection voltage line LM connects terminal M of the test cell module MD to the + terminal of the input operational amplifier INA1 and the - terminal of the input operational amplifier INA2. This causes the outputs of the input operational amplifiers INA1 and INA2 to be positive polarity.

[0025] The impedance detection circuit 3 also includes a current sensor 32 that measures the measurement AC current Im flowing through multiple test cell modules MD, a bandpass filter BPF connected to the output terminal of the current sensor 32, bandpass filters BPF1 and BPF2 connected to the output terminals of the input operational amplifiers INA1 and INA2, an A / D converter 33 that converts the AC current (current signal) Im and voltage signals V11, V12, V21, and V22 (examples of the ``response voltage'' of the present invention) output from the bandpass filters BPF, BPF1, and BPF2 from analog signals to digital signals, and a measurement control microcomputer 34 that measures the current signal Imd and voltage signals V11d, V12d, V21d, and V22d output from the A / D converter 33.

[0026] The output of the measurement AC current generating circuit 31 is controlled by a control signal CS from the measurement control microcomputer 34. The control signal CS includes signals that specify the frequency, amplitude, phase, and application timing of the applied current. The arrows attached to the measurement AC current Im in FIG. 1 indicate the flow path of the AC current Im. The measurement AC current generating circuit 31 is connected to the test cell module MD via the measurement current line LIm and the polarity switching circuit 2, allowing the measurement AC current Im to be applied from the measurement AC current generating circuit 31 to the test cell module MD. Application of this AC current Im generates a response voltage at terminals P, N, and M of the test cell module MD that corresponds to the internal impedance of the test cell module MD and the frequency, amplitude, and phase of the AC current Im. Therefore, the internal impedance of the test cell module MD can be measured by evaluating the response voltage based on the frequency, amplitude, and phase of the (known) measurement AC current Im commanded by the measurement control microcomputer 34.

[0027] This principle is based on Ohm's law, and a specific example is a two-phase lock-in amplifier (synchronous detection type) circuit. Furthermore, the amplitude A and phase θ of the AC current Im are used as the reference signal for measurement, and since the monitoring accuracy of this signal is the most important factor determining the accuracy of the measured impedance, a current sensor 32 is provided. The current sensor 32 is connected in series to the test cell module MD via the polarity switching circuit 2 and the measurement current line LIm. A precision shunt resistor (a resistive element with flat frequency characteristics) with low parasitic inductance of around several mΩ is useful as the current sensor 32.

[0028] Furthermore, batteries that charge and discharge large currents, such as those used in automobiles, have extremely low internal resistance (approximately 1 mΩ per cell), resulting in a response voltage signal amplitude of only a few mV when a measurement current is applied. This means that the impedance detection circuit 3 requires a very high signal-to-noise ratio. For this reason, after initial signal processing (e.g., removal of the cell's DC voltage component and common-mode voltage) is performed by the input operational amplifiers INA1 and INA2, bandpass filters BPF1 and BPF2 reduce components (noise) outside the desired frequency band (bandwidth limitation), extract the desired signal, and then A / D convert it (signal-to-noise ratio control). The measurement signal, quantized by the A / D converter 33, is sent to the measurement control microcomputer 34, which adjusts the detection signal level (scale conversion) and performs impedance calculations based on Ohm's law, outputting the calculation results Z11, Z12, Z21, and Z22.

[0029] (Independent Wiring for Detecting the Response Voltage Signal) Generally, the contact resistance of a relay switch is approximately 1 mΩ to 100 mΩ. Therefore, when measuring a 1 mΩ test cell module, the relay contacts account for the majority of the measured impedance. Focusing on this point, the degradation test device 1 provides signal lines (e.g., detection voltage lines LP and LN) for detecting the response voltage signal as independent wiring, separate from the wiring path including the polarity switching circuit 2 that carries the measurement AC current Im. This allows the degradation test device 1 to ensure that the detected response voltage signal does not include the contact resistance of the polarity switching switches 13A and 13B, which are relay switches, and thus enables accurate (resolution) measurement of the internal impedance of the test cell module MD. This is an example of the application of a wiring method known as the four-terminal method. The degradation test device 1 is particularly suitable for use in internal impedance measurement and degradation diagnosis of high-current output (rapid charge / discharge) cells with low internal impedance.

[0030] (Series Connection with Alternating Polarity) (1) Even-Number Connection FIG. 4 illustrates an example in which, for example, six test cell modules MD are connected in series via polarity switching circuits 2 and current connection lines LC to perform degradation diagnosis (cell impedance measurement). Note that the inspection device terminals INS are omitted from FIG. 4 and the following FIGS. 5, 6, and 10. As shown in FIG. 4, six polarity switching circuits 2 are provided, the same number as the test cell modules MD. In this connection example, the polarity switching circuits 2 include three non-inverting connection polarity switching circuits 21 and three inverting connection polarity switching circuits 22. As shown in FIG. 4, the non-inverting connection polarity switching circuits 21 and the inverting connection polarity switching circuits 22 are alternately arranged in the series connection direction. The orientation of the diodes included in the connection polarity switching circuits 2 is alternately switched in the series connection direction (i.e., diodes D1 and D2 are alternately arranged), thereby alternately switching the polarity of the output terminals of the polarity switching circuits 2. This allows the output voltage of the test cell module MD via the connection polarity switching circuit 2 to be approximately 0 V for each two modules. When the test cell modules MD are connected in series with their polarities alternately reversed, the positive and negative voltages (potentials) cancel each other out, and the voltage between both ends of the series connection becomes approximately 0 V.

[0031] The term "almost 0 V" here refers to the fact that the actual test cell module MD will have different voltages due to differences in degradation and charge capacity. Because the voltages of the battery cells CE contained in the test cell module MD vary slightly depending on the degree of degradation and charge capacity, the positive and negative voltages (potentials) will not completely cancel out and the voltage will not reach 0 V. However, it is quite possible to expect a low voltage of several volts (e.g., about 1 V). This allows the voltage across the series connection to be kept almost 0 V even if the number of test cell modules MD connected in series is increased. This prevents the voltage across the series connection from becoming too high, as will be discussed in the comparative example below. Therefore, the measurement AC current generating circuit 31 does not need to be a special circuit designed for high voltages.

[0032] 1, the output terminal of the polarity switching circuit 2 is connected to the input operational amplifiers INA1 and INA2, but there is no need to use special high-voltage operational amplifiers for the input operational amplifiers INA1 and INA2. As shown in FIG. 1, by setting the polarity directions of the series connection of the test cell modules MD in an opposite relationship (i.e., connecting the terminals P or N of two test cell modules MD adjacent in the series connection direction in series via the connection polarity switching circuit 2 and the current connection line LC), the circuit voltage applied to the input operational amplifiers INA1 and INA2 is the sum of the two series-connected battery cells CE, up to a maximum of 8.4 V. This series connection with alternating polarity switching is suitable for measurement methods using AC current.

[0033] (2) Odd-Number Connection: Figure 5 illustrates a case where, for example, five test cell modules MD are connected in series via polarity switching circuits 2 and current connection lines LC for degradation diagnosis. As shown in Figure 5, five polarity switching circuits 2 are provided, the same number as the test cell modules MD. In this example, the polarity switching circuits 2 include three non-inverting connection polarity switching circuits 21 and two inverting connection polarity switching circuits 22. As shown in Figure 5, the non-inverting connection polarity switching circuits 21 and the inverting connection polarity switching circuits 22 are alternately arranged in the series connection direction. By alternately switching the orientation of the diodes included in the connection polarity switching circuits 2 in the series connection direction (i.e., by alternately arranging diodes D1 and D2) and alternately switching the polarity of the output terminals of the polarity switching circuits 2, the output voltage via the connection polarity switching circuits 2 of the test cell modules MD can be kept nearly 0 V in units of two modules.

[0034] 5, the number of test cell modules MD is odd, and one module is left over when two modules are connected in units. Therefore, the total voltage of the five test cell modules MD connected in series is 8.4V, equivalent to one module. In the case of an odd number, the voltage at both ends is higher than in the case of an even number, but since the maximum voltage is equivalent to one module, there is no need to use a special high-voltage circuit for the measurement AC current generating circuit 31.

[0035] Furthermore, as in the case of an even number, in the case of an odd number, by making the polarity directions of the series connection of the test cell modules MD opposite each other (i.e., connecting the terminals P or N of two test cell modules MD adjacent in the series connection direction in series via the connection polarity switching circuit 2 and the current connection line LC), the circuit voltage applied to the input operational amplifiers INA1 and INA2 will be a maximum of 8.4 V in total for the two series cells. Therefore, there is no need to use special high-voltage compatible operational amplifiers for the input operational amplifiers INA1 and INA2.

[0036] (3) Comparative Example In the comparative example shown in Figure 6, six test cell modules MD are connected in series without the polarity switching circuit 2. In the comparative example, the total voltage of the six test cell modules MD connected in series is approximately 50.4 V. When the voltage across the series connection exceeds 30 V, the number of component options becomes limited. The higher the voltage across the series connection, the greater the need to use special high-voltage compatible circuits or special high-voltage compatible operational amplifiers, resulting in higher costs.

[0037] (Example of overall configuration of degradation test device) As shown in Fig. 7, the degradation test device 1 includes, in addition to the polarity switching circuit 2 and impedance detection circuit 3 described above, a degradation diagnosis device 4 and a diagnosis result storage device 5. Although not shown in Fig. 7, as described above, multiple test subject cell modules MD and multiple connection polarity switching circuits 2 are provided.

[0038] The impedance detection circuit 3 detects a response voltage (voltage signal) that appears at each terminal of the test cell module MD in response to the measurement current and the internal impedance of the test cell module MD, and calculates the internal impedance of each test cell module from the measurement current and the response voltage. The internal impedance calculated by the impedance detection circuit 3 is sent to the degradation diagnosis device 4 as impedance information.

[0039] The deterioration diagnosis device 4 acquires the impedance information transmitted from the impedance detection circuit 3. The deterioration diagnosis device 4 also acquires battery identification information (e.g., model, serial number) from the test cell module MD. The deterioration diagnosis device 4 then links the acquired impedance information to the battery identification information and diagnoses the degree of deterioration of each test cell module MD based on the acquired impedance information and battery identification information. The diagnosis results are transmitted to the diagnosis result storage device 5 as battery state information for each test cell module MD. The diagnosis result storage device 5 stores the battery state information for each test cell module MD transmitted from the deterioration diagnosis device 4. The diagnosis result storage device 5 is configured with any storage device, such as a hard disk drive (HDD) or a storage device using semiconductors.

[0040] (Effects of First Embodiment) As described above, the cell module degradation inspection device 1 according to the first embodiment of the present invention includes an impedance detection circuit 3 that detects a measurement AC current Im applied to a plurality of serially connected test cell modules MD and response voltages (e.g., voltage signals V11, V12, V21, and V22) appearing at each terminal of the plurality of test cell modules MD, and calculates the internal impedance (e.g., Z11, Z12, Z21, and Z22) of each of the plurality of test cell modules MD from the detected AC current Im and response voltages, and a connection polarity switching circuit 2 disposed between each terminal of the plurality of test cell modules MD and the impedance detection circuit 3. When the test cell module MD is connected to a polarity preset in the connection polarity switching circuit 2, this is referred to as a positive connection, and when the test cell module MD is connected to the polarity opposite to the preset polarity, this is referred to as a reverse connection. The connection polarity switching circuit 2 has the function of automatically switching the output polarity of the connection polarity switching circuit 2 to the same polarity as in the positive connection, even in the case of a reverse connection, by utilizing the stored power of the test cell module MD. The output polarity of the test cell module MD is set in units of the test cell module MD by combining inversion and non-inversion in the series connection direction.

[0041] This eliminates the need to match the connection polarity of the test cell module MD. This reduces the labor required and prevents measurement errors (mismeasurements) caused by reverse connections, making it easier to test the deterioration level of the test cell module MD. It also increases the design freedom of the input circuit of the impedance detection circuit 3. As a result, a highly accurate, low-cost measurement circuit can be realized.

[0042] For example, the connection polarity switching circuit 2 includes an output-inverting connection polarity switching circuit 22 that inverts the output polarity relative to the input polarity, and an output-non-inverting connection polarity switching circuit 21 that does not invert the output polarity relative to the input polarity. The same number of output-inverting connection polarity switching circuits 22 and output-non-inverting connection polarity switching circuits 21 are provided. The output-inverting connection polarity switching circuits 22 and the output-non-inverting connection polarity switching circuits 21 are alternately provided in the serial connection direction. This reduces the maximum voltage (common-mode voltage) in the impedance detection circuit 3. This increases the flexibility in the design of the impedance detection circuit 3's insulation measures, input circuit, and electronic component selection. As a result, a low-cost testing device can be realized.

[0043] For example, the connection polarity switching circuit 2 includes a diode D1 (or D2) that detects reverse connection based on the presence or absence of forward current, and switches 13A and 13B that are driven based on the presence or absence of forward current. When reverse connection occurs, the switches 13A and 13B switch from ON to OFF or from OFF to ON, switching the output polarity to the same polarity as in the case of forward connection. This allows the predetermined polarity to be automatically set based on the preset orientation of the diode D1 (or D2). This minimizes operational malfunctions (malfunctions) of polarity switching due to human error, noise, etc. As a result, it becomes possible to implement and manage appropriate degradation diagnosis of the test cell module MD, ultimately contributing to reduced testing costs.

[0044] For example, the system includes current lines (e.g., measurement current lines LIm and current connection lines LC) connecting the measurement AC current generating circuit 31 and multiple test cell modules MD in series, and voltage lines (e.g., detection voltage lines LP, LN, and LM) connecting each terminal of the multiple test cell modules MD to the impedance detection circuit 3. The current lines and voltage lines are independent wiring, and a connection polarity switching circuit 2 is inserted in the current lines. This allows for precise measurement of the low-impedance internal impedance of the test cell module MD. Furthermore, since the required electronic circuits and elements do not need to be high-voltage compatible, device and maintenance costs can be reduced and the device life can be extended. Furthermore, if the test cell module MD is for use in a vehicle, the aforementioned effects can be expected to reduce the cost of reusing on-board cells.

[0045] (Modification) As shown in FIG. 8 , the detection voltage line LP may connect the terminal P of the inspection equipment terminal INS (e.g., the inspection equipment terminal INS-2) to the negative terminal of the input operational amplifier INA1. The detection voltage line LN may connect the terminal N of the inspection equipment terminal INS (e.g., the inspection equipment terminal INS-2) to the positive terminal of the input operational amplifier INA2. When connected in this manner, the outputs of the input operational amplifiers INA1 and INA2 are negative (phase inverted). However, this does not cause any inconvenience because the negative output can be subjected to calculation processing such as absolute value conversion (sign deletion) by the measurement control microcomputer 34 to obtain a calculation result equivalent to that of the positive output.

[0046] 9 differs from the degradation inspection device 1 shown in FIG. 1 in that the detection voltage lines LP and LN are omitted. In the degradation inspection device 1A, the terminal P of the inspection device side terminal INS and the input terminal of the input operational amplifier are connected via a connection polarity switching circuit 2 rather than the detection voltage line LP. Also, in the degradation inspection device 1A, the terminal N of the inspection device side terminal INS and the input terminal of the input operational amplifier are connected via a connection polarity switching circuit 2 rather than the detection voltage line LN.

[0047] Even in this configuration, the deterioration test device 1A does not require matching the connection polarity of the test cell module MD, as with the deterioration test device 1 described in embodiment 1. This reduces the labor required and prevents measurement errors (erroneous measurements) due to reverse connections, making it easy to test the deterioration of the test cell module MD. Furthermore, the omission of the detection voltage lines LP and LN contributes to simplifying the configuration of the test device.

[0048] In the deterioration test device 1A, the wiring path for detecting the response voltage is a path that passes through the polarity switching circuit 2 and includes the contact resistance of the polarity switching switches 13A and 13B. For this reason, it can be said that the deterioration test device 1 of embodiment 1 has higher measurement accuracy (resolution) for the internal impedance of the test cell module MD than the deterioration test device 1A.

[0049] 10, in the deterioration test device 1A, a single input operational amplifier INA may be connected to the output terminal of a single connection polarity switching circuit 2, instead of two input operational amplifiers INA1 and INA2. Even in this configuration, there is no need to match the connection polarity of the test cell module MD, and deterioration testing of the test cell module MD can be easily performed.

[0050] 10, the input operational amplifier INA may include a non-inverting operational amplifier A1 that does not invert the output polarity and an inverting operational amplifier A2 that inverts the output polarity. The non-inverting operational amplifier A1 may be connected to the output terminal of a connection polarity switching circuit 21 with a non-inverting output, and the inverting operational amplifier A2 may be connected to the output terminal of a connection polarity switching circuit 22 with an inverting output. This further inverts the output polarity of the inverting operational amplifier A2 to the same polarity as the test cell module MD, allowing it to be treated as the same polarity in subsequent signal processing and impedance calculations.

[0051] 10 is a hardware countermeasure, but as another example, it may be designed as a software countermeasure. As a software countermeasure, although not shown, instead of unifying the polarities of all input operational amplifiers INA (for example, unifying them to non-inverting operational amplifier A1), there is a method of unifying the polarity by multiplying the inverted signal by -1 in signal processing, or a method of calculating the absolute value (squaring operation). Using these methods, the signals output from the input operational amplifier INA may be unified in polarity for degradation diagnosis processing.

[0052] <Other Embodiments> As described above, the present invention has been described using the first and second embodiments and their modifications, but the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. For example, the measurement AC current generating circuit 31 shown in Figure 1 etc. may be provided outside the impedance detection circuit 3, and may be a measurement current generating device externally attached to the impedance detection circuit 3. Also, the inspection device side terminal INS may be omitted, and the test cell module MD and the connection polarity switching circuit 2 may be connected without passing through the inspection device side terminal INS.

[0053] As such, various alternative embodiments and modifications will be apparent to those skilled in the art from this disclosure. It goes without saying that the present technology includes various embodiments not described herein. Various omissions, substitutions, and modifications of components can be made without departing from the spirit of the above-described embodiments. Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0054] 1, 1A... Deterioration inspection device, 2... Connection polarity switching circuit, 3... Impedance detection circuit, 4... Deterioration diagnosis device, 5... Diagnosis result storage device, 11... Relay drive coil, 12... Current limiting resistor, 13A, 13B... Switch, 21... Connection polarity switching circuit with non-inverting output, 22... Connection polarity switching circuit with inverting output, 31... Measurement AC current generation circuit, 32... Current sensor, 33... A / D converter, 34... Measurement control microcomputer, A1... Non-inverting operational amplifier, A2... Inverting operational amplifier, BPF, BPF1, B PF2...bandpass filter, CE...battery cell, CS...control signal, D1, D2...diode, Im...AC current (current signal), INA, INA1, INA2...input operational amplifier, INS...inspection equipment side terminal, LC...current connection line, LIm...measurement current line, LM, LN, LP...detection voltage line, M, N, P...terminals, MD, MD-1 to MD-6...tested cell module, V11, V11d, V12, V12d, V21, V21d, V22, V22d...voltage signal, Z11, Z12, Z21, Z22...computation result

Claims

an impedance detection circuit that detects a measurement current applied to a plurality of serially connected cell modules and a response voltage appearing at each terminal of the plurality of cell modules, and calculates the internal impedance of each of the plurality of cell modules from the measurement current and the response voltage; a connection polarity switching circuit disposed between each terminal of the plurality of cell modules and the impedance detection circuit, When the cell module is connected to the polarity preset in the connection polarity switching circuit, this is called a positive connection, and when the cell module is connected to the polarity opposite to the preset polarity, this is called a reverse connection. The connection polarity switching circuit Even in the case of the reverse connection, the output polarity of the connection polarity switching circuit is automatically switched to the same polarity as in the case of the positive connection by utilizing the stored power of the cell module, The cell module inspection device, wherein the output polarity is set in a unit of the cell module by combining inversion and non-inversion in the series connection direction. 　 The connection polarity switching circuit a connection polarity switching circuit with an output inversion specification that inverts the output polarity with respect to the series connection direction; 2. The cell module inspection device according to claim 1, further comprising: a connection polarity switching circuit of output non-inversion type that does not invert the output polarity with respect to the direction of the series connection.

3. The cell module inspection device according to claim 2, wherein the number of the inverting output type connection polarity switching circuits and the number of the non-inverting output type connection polarity switching circuits are the same.

4. The cell module inspection device according to claim 2, wherein the connection polarity switching circuits of the output inversion type and the connection polarity switching circuits of the output non-inversion type are alternately provided in the direction of the series connection. 　 The connection polarity switching circuit a diode that detects the reverse connection based on the presence or absence of a forward current; a switch that is driven by the presence or absence of the forward current; 3. The cell module inspection device according to claim 1, wherein the switch is switched from on to off or from off to on in the case of the reverse connection, thereby switching the output polarity to the same polarity as in the case of the positive connection. 　 a current line connecting the measurement current application device and the plurality of cell modules in series; a voltage line connecting each terminal of the plurality of cell modules to the impedance detection circuit; the current line and the voltage line are independent wirings, 3. The cell module inspection device according to claim 1, wherein the connection polarity switching circuit is inserted in the current line.

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