JP6318883B2 - Impedance measuring device - Google Patents

Description

  The present invention relates to an impedance measuring device that measures the impedance of a laminated battery.

  Patent Document 1 proposes an apparatus for measuring the internal resistance of a laminated battery while power is supplied from the laminated battery to a load.

  This measuring apparatus has two variable power supplies that output alternating current of the same frequency to each of the positive electrode terminal and the negative electrode terminal of the multilayer battery so that current does not leak to the load connected to the multilayer battery. Then, the measuring device is configured to subtract the potential of the halfway terminal located between the positive electrode terminal and the negative electrode terminal from the potential of the positive electrode terminal of the laminated battery, and from the potential of the negative electrode terminal, An AC potential difference on the negative electrode side from which the potential is pulled is detected.

  Furthermore, the measuring device separately detected the AC current output from the variable power source by controlling the two variable power sources separately so that both the positive electrode side and negative electrode side AC potential differences were set to predetermined reference values. The internal resistance of the laminated battery is measured based on the AC potential difference.

International Publication No. 2012/077450

  In the measuring apparatus as described above, the two variable power sources are controlled independently of each other so that the positive-side AC potential difference and the negative-side AC potential difference coincide. For this reason, there existed a problem that the structure of a measuring apparatus will become complicated and manufacturing cost will increase.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide an impedance measuring device that has a simple configuration and suppresses manufacturing costs while maintaining the accuracy of measuring impedance. To do.

  According to an aspect of the present invention, the impedance measuring device includes a first power supply unit that outputs a predetermined alternating current to one of the positive electrode and the negative electrode of the stacked battery in which the plurality of battery cells are stacked. And second power supply means for outputting an alternating current including a frequency component of the alternating current output from the first power supply means to the other electrode of the positive electrode and the negative electrode. The impedance measuring apparatus detects the AC potential difference between the one electrode and the halfway point of the multilayer battery, and detects the AC potential difference between the other electrode and the halfway point. 2 detection means. Further, the impedance measuring device uses the AC potential difference detected by the first detection means as a reference value for matching the AC potentials generated at the positive electrode and the negative electrode, and the AC potential difference detected by the second detection means is different from the reference value. As mentioned above, the adjusting means for adjusting the alternating current output from the second power supply means is included. Further, the impedance measuring device includes an arithmetic unit that calculates an impedance of the stacked battery based on the alternating current adjusted by the adjusting unit and an alternating potential difference generated in the stacked battery by the alternating current. It is characterized by.

  According to this aspect, by adjusting only the other AC current based on the AC potential difference generated between the electrode of the laminated battery to which the predetermined AC current is input and the midpoint, the AC potential difference between the two is reduced. Can match each other. For this reason, it becomes possible to fix one alternating current, maintaining the precision which measures an impedance, and it can suppress an increase in manufacturing cost while making an impedance measuring device simple composition.

FIG. 1A is a diagram illustrating an example of a laminated battery that is a measurement target of the impedance measuring apparatus according to the first embodiment of the present invention. FIG. 1B is an exploded view showing the structure of the battery cell formed in the laminated battery. FIG. 2 is a diagram illustrating a basic configuration of the impedance measuring apparatus according to the present embodiment. FIG. 3 is a diagram illustrating a configuration of a DC blocking unit and a detection unit that detects an AC potential difference generated between an electrode and a halfway point. FIG. 4 is a diagram illustrating a fixed power supply unit that outputs a constant alternating current to one electrode of the laminated battery. FIG. 5 is a diagram illustrating a variable power supply unit that can increase or decrease an alternating current output to the other electrode of the stacked battery. FIG. 6 is a diagram illustrating a configuration of an AC adjustment unit that adjusts an AC current output from the variable power supply unit. FIG. 7 is a diagram illustrating a configuration of a calculation unit that calculates the internal impedance of the laminated battery. FIG. 8 is a flowchart showing an example of an equipotential control method by the impedance measuring apparatus. FIG. 9 is a time chart showing an example of the equipotential control method. FIG. 10 is a diagram showing potentials generated at the positive electrode and the negative electrode of the laminated battery by equipotential control. FIG. 11 is a diagram showing a basic configuration of an impedance measuring apparatus according to the second embodiment of the present invention. FIG. 12 is a diagram illustrating a configuration of the AC adjustment unit in the present embodiment. FIG. 13 is a diagram illustrating a configuration of the detection unit in the present embodiment. FIG. 14 is a flowchart showing an example of an equipotential control method by the impedance measuring apparatus. FIG. 15 is a time chart showing an example of the equipotential control method. FIG. 16 is a diagram illustrating a configuration of a fixed power supply unit according to the third embodiment of the present invention. FIG. 17 is a flowchart showing an example of the equipotential control method in the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1A is a diagram illustrating an example of a laminated battery that is a measurement target measured by the impedance measurement apparatus according to the first embodiment of the present invention. FIG. 1A shows an external perspective view of a fuel cell stack 1 in which a plurality of battery cells are stacked as an example of a stacked battery.

  As shown in FIG. 1A, the fuel cell stack 1 includes a plurality of power generation cells 10, a current collecting plate 20, an insulating plate 30, an end plate 40, and four tension rods 50.

  The power generation cell 10 is a so-called battery cell and indicates one of a plurality of fuel cells stacked on the fuel cell stack 1. The power generation cell 10 generates an electromotive voltage of about 1 V (volt), for example. The detailed configuration of the power generation cell 10 will be described later with reference to FIG. 1B.

  The current collecting plates 20 are respectively arranged outside the stacked power generation cells 10. The current collecting plate 20 is formed of a gas impermeable conductive member, for example, dense carbon. A current collecting plate 20 corresponding to a positive electrode (hereinafter referred to as “positive electrode”) of the fuel cell stack 1 is provided with a positive electrode terminal 211, and a negative electrode (hereinafter referred to as “negative electrode”) of the fuel cell stack 1. A negative electrode terminal 212 is provided on the current collecting plate 20 corresponding to. Note that electrons e − generated in the power generation cell 10 are taken out from the negative electrode terminal 212 to the outside.

  Further, a midway terminal 213 is provided in the power generation cell 10 located in the middle (middle point) between the positive electrode terminal 211 and the negative electrode terminal 212. The midpoint terminal 213 is connected to the power generation cell 10 located in the middle among the plurality of power generation cells 10 stacked from the positive electrode terminal 211 to the negative electrode terminal 212. The halfway point terminal 213 may be provided in the power generation cell 10 located at a position (halfway point) deviated from the middle point between the positive electrode terminal 211 and the negative electrode terminal 212.

  The insulating plates 30 are respectively arranged outside the current collecting plates 20. The insulating plate 30 is formed of an insulating member such as rubber.

  The end plate 40 is disposed outside the insulating plate 30. The end plate 40 is made of a rigid metal material such as steel.

  One end plate 40 (the left front end plate 40 in FIG. 1A) has an anode supply port 41a, an anode discharge port 41b, a cathode supply port 42a, a cathode discharge port 42b, and a cooling water supply port 43a. A cooling water discharge port 43b is provided. In the present embodiment, the anode discharge port 41b, the cooling water discharge port 43b, and the cathode supply port 42a are provided on the right side in the drawing. The cathode discharge port 42b, the cooling water supply port 43a, and the anode supply port 41a are provided on the left side in the drawing.

  The tension rods 50 are disposed near the four corners of the end plate 40, respectively. The fuel cell stack 1 has a hole (not shown) penetrating therethrough. The tension rod 50 is inserted through the through hole. The tension rod 50 is formed of a rigid metal material such as steel. The tension rod 50 is insulated on the surface in order to prevent an electrical short circuit between the power generation cells 10. A nut (not shown because it is in the back) is screwed into the tension rod 50. The tension rod 50 and the nut tighten the fuel cell stack 1 in the stacking direction.

  As a method of supplying hydrogen as anode gas to the anode supply port 41a, for example, there are a method of directly supplying hydrogen gas from a hydrogen storage device, a method of reforming and supplying hydrogen-containing fuel, and the like. Examples of the fuel containing hydrogen include natural gas, methanol, and gasoline. Air is generally used as the cathode gas supplied to the cathode supply port 42a.

  FIG. 1B is an exploded view showing the structure of the power generation cells 10 stacked on the fuel cell stack 1.

  As shown in FIG. 1B, in the power generation cell 10, an anode separator (anode bipolar plate) 12a and a cathode separator (cathode bipolar plate) 12b are arranged on both surfaces of a membrane electrode assembly (MEA) 11. Is the structure.

  In the MEA 11, electrode catalyst layers 112 are formed on both surfaces of an electrolyte membrane 111 made of an ion exchange membrane. A gas diffusion layer (GDL) 113 is formed on the electrode catalyst layer 112.

  The electrode catalyst layer 112 is formed of, for example, carbon black particles on which platinum is supported.

  The GDL 113 is formed of a member having sufficient gas diffusibility and conductivity, such as carbon fiber.

  The anode gas supplied from the anode supply port 41a flows through this GDL 113a, reacts with the anode electrode catalyst layer 112 (112a), and is discharged from the anode discharge port 41b.

  The cathode gas supplied from the cathode supply port 42a flows through this GDL 113b, reacts with the cathode electrode catalyst layer 112 (112b), and is discharged from the cathode discharge port 42b.

  The anode separator 12a is stacked on one side of the MEA 11 (back side in FIG. 1B) via the GDL 113a and the seal 14a. The cathode separator 12b is overlaid on one side (the surface in FIG. 1B) of the MEA 11 via the GDL 113b and the seal 14b. The anode separator 12a and the cathode separator 12b are formed by press-molding a separator base made of metal such as stainless steel so that a reaction gas channel is formed on one surface and alternately arranged with the reaction gas channel on the opposite surface. A cooling water flow path is formed. As shown in FIG. 1B, the anode separator 12a and the cathode separator 12b are overlapped to form a cooling water flow path.

  The MEA 11, the anode separator 12a, and the cathode separator 12b are respectively formed with holes 41a, 41b, 42a, 42b, 43a, 43b, which are stacked to be an anode supply port 41a, an anode discharge port 41b, and a cathode supply port. 42a, cathode discharge port 42b, cooling water supply port 43a and cooling water discharge port 43b are formed.

  FIG. 2 is a diagram showing a basic configuration of the impedance measuring apparatus 5 in the embodiment of the present invention.

  The fuel cell stack 1 is a stacked battery that is connected to the load 3 and supplies power to the load 3, and is mounted on a vehicle, for example. The fuel cell stack 1 has an impedance inside. The load 3 is, for example, an auxiliary machine used for power generation of the electric motor or the fuel cell stack 1. The auxiliary machine connected to the fuel cell stack 1 is, for example, a compressor that supplies cathode gas to the fuel cell stack 1, a heater that heats the cooling water flowing through the fuel cell stack 1 when the fuel cell stack 1 is warmed up, etc. It is.

  The control unit (C / U) 6 controls the operation state of the fuel cell stack 1 such as the power generation state, the wet state, the internal pressure state, and the temperature state of the fuel cell stack 1 according to the operating state of the load 3.

  For example, the control unit 6 controls the gas flow rate of the cathode gas and the anode gas supplied to the fuel cell stack 1 according to the generated power requested from the load 3. Further, in the fuel cell stack 1, when the electrolyte membrane 111 is in a dry state, the power generation performance is degraded. As a countermeasure, the control unit 6 uses the internal resistance value of the fuel cell stack 1 correlated with the wetness of the electrolyte membrane 111 so that the electrolyte membrane 111 does not become dry or excessively wet. Adjust.

  The impedance measuring device 5 measures the internal impedance of the fuel cell stack 1. In the present embodiment, the impedance measuring device 5 measures the internal resistance R of the fuel cell stack 1 and transmits the measured value of the internal resistance R to the control unit 6. When the control unit 6 receives the measurement value of the internal resistance R of the fuel cell stack 1 from the impedance measurement device 5, the control unit 6 controls the wet state of the fuel cell stack 1 based on the measurement value of the internal resistance R.

  The impedance measuring device 5 includes a positive side DC cutoff unit 511, a negative side DC cutoff unit 512, a midpoint DC cutoff unit 513, a positive side detection unit 521, a negative side detection unit 522, and a positive side power supply unit 531. , A negative power supply unit 532, an AC adjustment unit 540, and a calculation unit 550.

  Details of the positive-side DC blocking unit 511, the negative-side DC blocking unit 512, the mid-point DC blocking unit 513, the positive-side detecting unit 521, and the negative-side detecting unit 522 will be described with reference to FIG.

  The positive side DC cutoff unit 511 is a first DC cutoff unit connected between the positive terminal 211 of the fuel cell stack 1 and the positive side power source unit 531.

  The negative electrode side DC blocking unit 512 is a second DC blocking unit connected between the negative electrode terminal 212 of the fuel cell stack 1 and the negative electrode side power source unit 532.

  The midpoint DC blocking unit 513 is connected to the midpoint terminal 213 of the fuel cell stack 1. The DC blockers 511 to 513 block the DC signal but pass the AC signal. The DC blockers 511 to 513 are realized by a capacitor or a transformer, for example. Note that the halfway DC blocking unit 513 indicated by the wavy line can be omitted.

  In the present embodiment, as shown in FIG. 3, each of the DC blocking units 511 to 513 is realized by a capacitor.

  The positive electrode side detection unit 521 has a potential difference (hereinafter referred to as “AC potential difference V1”) between an AC potential Va that is an AC potential component generated at the positive electrode terminal 211 and an AC potential Vc that is an AC potential component generated at the midpoint terminal 213. .) Is the first detection means for detecting.

  The positive electrode side detection unit 521 outputs a detection signal whose value changes according to the amplitude of the AC potential difference V1 to the AC adjustment unit 540 and the calculation unit 550. For example, the level of the detection signal increases as the AC potential difference V1 increases, and the level of the detection signal decreases as the AC potential difference V1 decreases.

  As for the positive electrode side detection unit 521, the first input terminal 521A is connected to the positive electrode terminal 211 via the DC blocking unit 511, the second input terminal 521B is grounded, the output terminal 521C is the AC adjustment unit 540, and the calculation unit 550. Connected to both sides.

  The positive electrode side detection unit 521 includes a differential amplifier 5211, a band pass filter (BPF) 5212, an amplifier circuit 5213, and a synchronous detection circuit 5214.

  The differential amplifier 5211 has an AC signal that passes through the DC blocking unit 511 among signals output from the positive terminal 211 and an AC signal that passes through the DC blocking unit 513 among signals output from the midway terminal 213. A detection signal obtained by subtracting the signal component of the potential Vc is output.

  The band-pass filter 5212 is an extraction circuit that removes unnecessary signals included in the detection signal and extracts only signal components in a necessary frequency band. Specifically, the band-pass filter 5212 passes a signal component having the same frequency as that of the alternating current I1 in the detection signal output from the differential amplifier 5211, and removes a signal component in another frequency band. .

  The amplifier circuit 5213 amplifies the detection signal output from the band pass filter 5212 and outputs it. The amplification factor (gain) of the amplifier circuit 5213 is determined by experiments or the like.

  The synchronous detection circuit 5214 extracts only the signal component having the same frequency as the alternating current I1 and the same phase as the alternating current I1, that is, the actual axis component of the detection signal, from the detection signal output from the amplification circuit 5213. This is an extraction circuit.

  Specifically, the synchronous detection circuit 5214 multiplies the detection signal by a signal having the same frequency fb as the alternating current I1 and having the same phase as that of the alternating current I1, and the multiplied alternating detection signal. Is converted into a DC detection signal V1. The smoothed detection signal V1 changes according to the amplitude of the AC potential difference V1. Instead of the synchronous detection circuit 5214, a circuit that outputs an average value or an effective value of the AC potential difference V1 may be provided.

  In this way, the positive electrode side detection unit 521 generates a detection signal proportional to the amplitude of the AC potential difference V1, and outputs the detection signal V1 to the AC adjustment unit 540 and the calculation unit 550.

  The negative electrode side detection unit 522 generates a potential difference (hereinafter referred to as “AC potential difference V2”) between an AC potential Vb that is an AC component generated at the negative electrode terminal 212 and an AC potential Vc that is an AC component generated at the midpoint terminal 213. It is the 2nd detection means to detect.

  The negative electrode side detection unit 522 outputs a detection signal whose value changes according to the amplitude of the AC potential difference V2 to the calculation unit 550. As for the negative electrode side detection unit 522, the first input terminal 522A is connected to the negative electrode terminal 212 via the DC blocking unit 512, the second input terminal 522B is grounded, the output terminal 522C is the AC adjustment unit 540, and the calculation unit 550. Connected to both sides.

  The negative electrode side detection unit 522 includes a differential amplifier 5221, a band pass filter (BPF) 5222, an amplifier circuit 5223, and a synchronous detection circuit 5224. Since these configurations are basically the same as the configuration of the positive electrode side detection unit 521, the description thereof is omitted here.

  The positive power supply unit 531 outputs an alternating current I1 having a reference frequency fb determined to measure the internal impedance of the fuel cell stack 1 to the positive terminal 211.

  The positive power supply unit 531 is a fixed power supply in which the amplitude and phase of the alternating current I1 are fixed. That is, in the present embodiment, the positive power source unit 531 is a first power supply unit that outputs a predetermined alternating current. The positive power supply unit 531 is realized using a voltage-current conversion circuit such as an operational amplifier.

  The detailed configuration of the positive power supply unit 531 will be described with reference to FIG.

  The positive power supply unit 531 includes a fixed power supply 5311, an AC signal generator 5312, a multiplier 5313, and a voltage / current conversion circuit 5314.

  Fixed power supply 5311 outputs a DC voltage having a predetermined fixed value. The fixed power source 5311 outputs a DC voltage of, for example, several hundred mV (millivolt).

  The AC signal generator 5312 is an AC source that oscillates an AC signal having a reference frequency fb. The reference frequency fb is set to a value suitable for measuring the internal impedance of the fuel cell stack 1. The reference frequency fb is set to 1 kHz (kilohertz), for example.

  The multiplier 5313 multiplies the DC voltage signal output from the fixed power supply 5311 by the AC signal having the reference frequency fb to generate an AC voltage Vi1 having the reference frequency fb and outputs the AC voltage Vi1 to the voltage-current conversion circuit 5314.

  The voltage-current conversion circuit 5314 converts the alternating voltage Vi1 having the reference frequency fb into the alternating current I1, and outputs the alternating current I1 to the direct current cut-off unit 511 via the output terminal 531A.

  The voltage-current conversion circuit 5314 adjusts the alternating current I1 in accordance with the operational amplifier OA1 that outputs the alternating current I1 corresponding to the alternating voltage Vi1, the detection resistance element Rs, and the detection voltage Vs1 generated in the detection resistance element Rs. An operational amplifier OA2 and resistance elements R1 to R5 are included.

  The operational amplifier OA1 outputs an alternating current I1 based on the alternating voltage Vi1. The non-inverting input terminal of the operational amplifier OA1 is connected to the output terminal of the multiplier 5313, and the inverting input terminal is connected to the operational amplifier OA2 for current adjustment via the resistance element R5. The output terminal of the operational amplifier OA1 is grounded via the resistance element R2 and the resistance element R3.

  The detection resistance element Rs is a resistance element provided for detecting the alternating current I1 output from the operational amplifier OA1. The detection voltage Vs1 generated at both ends of the detection resistance element Rs is a value obtained by multiplying the current value of the alternating current I1 by the resistance value of the detection resistance element Rs. One end of the detection resistance element Rs is connected to the output terminal of the operational amplifier OA1, and the other end of the detection resistance element Rs is connected to the DC blocking unit 511 via the output terminal of the voltage-current conversion circuit 5314.

  The operational amplifier OA2 is a detection circuit that detects the detection voltage Vs1 generated in the detection resistance element Rs. The detection signal Vs1 output from the operational amplifier OA2 is fed back to the inverting input terminal of the operational amplifier OA1. Thereby, the operational amplifier OA1 adjusts the alternating current I1 according to the detection signal Vs1 so that the alternating current I1 matches the alternating voltage Vi1.

  As described above, the AC voltage Vi1 whose amplitude is fixed by the fixed power supply 5311 is input to the non-inverting input terminal of the operational amplifier OA1, and the operational amplifier OA1 outputs a current I1 having a constant amplitude based on the AC voltage Vil.

  The operational amplifier OA2 detects the detection voltage Vs1 generated in the detection resistance element Rs and outputs it to the inverting input terminal of the operational amplifier OA1. As a result, the operational amplifier OA1 amplifies the alternating current I1 so that the alternating current I1 matches the alternating voltage Vi1.

  Note that the resistance values of the resistance elements R <b> 1 to R <b> 5 are appropriately set according to the design of the impedance measuring device 5.

  In this embodiment, the example in which the voltage-current conversion circuit 5314 is configured using the general-purpose operational amplifiers OA1 and OA2 has been described. However, two differential amplifiers (instrumentation amplifiers) are used instead of the two operational amplifiers OA1 and OA2. May be.

  Next, the configuration of the negative power supply unit 532 will be described with reference to FIG.

  The negative power supply unit 532 outputs an alternating current I2 having the same reference frequency fb as the alternating current I1 to the negative terminal 212. The negative power supply unit 532 is a variable power supply that can change the amplitude of the alternating current I2.

  In the present embodiment, the amplitude of the AC current I2 output from the negative power supply unit 532 is controlled by the AC adjustment unit 540. That is, the negative-side power supply unit 532 is a second power supply unit that outputs an alternating current I2 having an amplitude adjusted by the AC adjusting unit 540.

  The negative power supply unit 532 includes a voltage / current conversion circuit 5324 and a current detection circuit 5325.

  The AC voltage Vi2 output from the AC adjustment unit 540 is input to the control terminal 532B of the voltage-current conversion circuit 5324 as a command value for the AC current I2. The voltage-current conversion circuit 5324 is a variable power supply unit that changes the amplitude of the alternating current I2 according to the alternating voltage Vi2 via the output terminal 532A.

  The voltage-current conversion circuit 5324 includes an operational amplifier OA1 that outputs an alternating current I2 corresponding to the alternating voltage Vi2, a detection resistance element Rs, and an operational amplifier OA2 that adjusts the alternating current I2 according to the voltage Vs2 generated at both ends of the detection resistance element Rs. And resistance elements R1 to R5. Note that these configurations are basically the same as the voltage-current conversion circuit 5314 of the positive-side power supply unit 531, and thus detailed description thereof is omitted here.

  The current detection circuit 5325 is connected to the output terminal of the operational amplifier OA2. The current detection circuit 5325 detects the amplitude of the alternating current I2 based on the detection voltage Vs2 detected by the operational amplifier OA2.

  In the present embodiment, the current detection circuit 5325 is a rectifier circuit that rectifies the detection voltage Vs2, and generates a DC detection signal I2 that is proportional to the amplitude of the AC current I2. For example, the detection signal I2 increases as the amplitude of the alternating current I2 increases, and the detection signal I2 decreases as the amplitude of the alternating current I2 decreases.

  As described above, the operational amplifier OA1 outputs the alternating current I2 based on the alternating voltage Vi2 whose amplitude is changed, and the operational amplifier OA2 detects the detection voltage Vs2 generated in the detection resistance element Rs to detect the inverting input terminal of the operational amplifier OA1. Output to.

  As a result, the operational amplifier OA1 amplifies the alternating current I2 so that the alternating current I2 matches the alternating voltage Vi2. That is, the operational amplifier OA1 corresponds to an output adjustment circuit that adjusts the alternating current I2 output based on the alternating voltage Vi2 in accordance with the detection signal Vs2 of the alternating current I2 detected by the operational amplifier OA2.

  When the amplitude of the AC voltage Vi2 is changed by the AC adjustment unit 540, the operational amplifier OA1 amplifies the amplitude of the AC current I2 according to the detection signal Vs2 output from the operational amplifier OA2. Current detection circuit 5325 detects the amplitude of alternating current I2 based on detection signal Vs2, and outputs the detected amplitude to calculation unit 550.

  In addition to the voltage-current conversion circuit 5324, the negative-side power supply unit 532 has a more complicated configuration than the power supply circuit including the fixed power supply 5311, the AC signal generator 5312, and the multiplier 5313 of the positive-side power supply unit 531. A current detection circuit 5325 is provided. For this reason, the positive-side power supply unit 531 can reduce the circuit configuration to the extent that the current detection circuit 5325 can be omitted, and the manufacturing cost can be reduced.

  In the voltage-current conversion circuit 5324, the alternating current I2 detected by the detection resistance element Rs is fed back to the operational amplifier OA1 by the operational amplifier OA2. The detection signal output from the operational amplifier OA2 is rectified by the current detection circuit 5325 and output to the arithmetic unit 550.

  As described above, the signal detected by the detection circuit including the detection resistance element Rs and the operational amplifier OA2 is used as the value of the alternating current I2 that is necessary for the calculation unit 550 to calculate the internal resistance. That is, the detection circuit constituting the voltage-current conversion circuit 5324 is also used as a circuit for detecting the value of the alternating current I2 necessary for the calculation in the calculation unit 550. For this reason, since it is not necessary to newly provide a circuit for detecting the value of the alternating current I2, the circuit configuration of the impedance measuring device 5 can be simplified.

  Next, the configuration of the AC adjustment unit 540 will be described with reference to FIG.

  The AC adjusting unit 540 outputs an AC current output from one of the positive power supply unit 531 and the negative power supply unit 532 so that the positive AC potential Va and the negative AC potential Vb coincide with each other. Adjusting means for adjusting the amplitude and phase of the.

  In the present embodiment, the reference terminal 540A of the AC adjustment unit 540 is connected to the output terminal 521C of the positive detection unit 521 shown in FIG. 3, and the input terminal 540B is the output of the negative detection unit 522 shown in FIG. Connected to terminal 522C. The output terminal 540C is connected to the control terminal 532B of the negative power supply unit 532 shown in FIG.

  The AC adjustment unit 540 fixes the AC current I1 output from the positive power supply unit 531 without adjusting the amplitude, and adjusts only the amplitude of the AC current I2 output from the negative power supply unit 532. The AC adjustment unit 540 is realized by, for example, a PI (Proportional Integral) control circuit.

  The AC adjustment unit 540 sets the detection signal V1 output from the positive electrode side detection unit 521 as a reference voltage Vs that makes the positive electrode side AC potential Va and the negative electrode side AC potential Vb coincide with each other. Then, the AC adjustment unit 540 adjusts the amplitude of the AC current I2 so that the detection signal V2 output from the negative electrode side detection unit 522 matches the reference voltage Vs.

  As a result, the amplitude level of the AC potential difference V1 on the positive electrode side and the amplitude level of the AC potential difference V2 on the negative electrode side become equal, and the AC potential Va on the positive electrode side and the AC potential Vb on the negative electrode side match.

  AC adjustment unit 540 includes a subtractor 541, an integration circuit 542, a multiplier 543, and an AC signal generator 544. The AC signal generator 544 has the same configuration as that of the AC signal generator 5312 shown in FIG. 4, and generates an AC signal having a predetermined reference frequency fb.

  The subtracter 541 outputs a difference signal proportional to the deviation width from the reference voltage Vs by subtracting the reference voltage Vs from the detection signal V2 output from the negative electrode side detection unit 522. For example, the difference signal level increases as the deviation width from the reference voltage Vs increases. The reference voltage Vs is a value serving as a reference for making the AC potential Va and the AC potential Vb coincide with each other.

  In the present embodiment, the detection signal V1 input from the positive electrode side detection unit 521 to the reference terminal 540A is set as the reference voltage Vs. As a result, the amplitude of the AC potential difference V2 is amplified so as to converge to the amplitude value of the AC potential difference V1.

  The integration circuit 542 integrates the difference signal output from the subtractor 541 to average the difference signal or adjust the sensitivity. Then, the integration circuit 542 outputs the integrated difference signal to the multiplier 543.

  The multiplier 543 generates the AC voltage Vi2 that converges the amplitude of the AC potential difference V2 to the reference voltage Vs by multiplying the AC signal of the reference frequency fb output from the AC signal generator 544 by the difference signal. For example, the amplitude of the AC voltage Vi2 increases as the level of the difference signal output from the subtractor 541 increases.

  The multiplier 543 outputs the AC voltage Vi2 to the negative power source unit 532 as a command signal. The AC voltage Vi2 is input to the control terminal 532B of the negative power source unit 532 via the output terminal 540C, and is converted into an AC current I2.

  As described above, the AC adjustment unit 540 adjusts the amplitude of the AC current I2 output from the negative power supply unit 532 so that the detected amplitude of the AC potential difference V2 matches the amplitude Vs of the AC potential difference V1.

  For this reason, since the AC potential Va and the AC potential Vb are controlled to the same level, the AC potential superimposed on the positive terminal 211 coincides with the AC potential superimposed on the negative terminal 212. Thereby, it is possible to prevent the alternating currents I1 and I2 output from the impedance measuring device 5 to the fuel cell stack 1 from leaking toward the load 3. In the following, controlling the positive power supply unit 531 and the negative power supply unit 532 so that the AC potential Va and the AC potential Vb are equal to each other is referred to as “equipotential control”.

  Next, the structure of the calculating part 550 is demonstrated with reference to FIG.

  The calculation unit 550 is a calculation unit that calculates the internal impedance of the fuel cell stack 1 based on the amplitudes of the AC potential differences V1 and V2 adjusted by the AC adjustment unit 540 and the amplitudes of the AC currents I1 and I2.

  The calculation unit 550 is connected to the output terminal 521C of the positive electrode side detection unit 521 shown in FIG. 3 and the output terminal 522C of the negative electrode side detection unit 522. Further, since a constant alternating current I1 is output from the positive power supply unit 531, the amplitude value of the alternating current I1 is recorded in advance in the calculation unit 550, and the current of the negative power supply unit 532 shown in FIG. Only the detection circuit 5325 is connected.

  Therefore, detection signals indicating the amplitudes of the AC potential differences V1 and V2 are input from the positive electrode side detection unit 521 and the negative electrode side detection unit 522 to the calculation unit 550, and detection indicating the amplitude of the AC current I2 is performed from the negative electrode side power supply unit 532. A signal is input.

  The calculation unit 550 includes an AD (Analog Digital) converter 551 and a microcomputer chip 552.

  The AD converter 551 converts the detection signal of the alternating current I2, which is an analog signal, and the detection signals of the alternating potential differences V1 and V2 into digital numerical signals, and transfers them to the microcomputer chip 552.

  In the microcomputer chip 552, programs for calculating the internal resistance Rn and the internal resistance R of the entire fuel cell stack 1 are stored in advance. The microcomputer chip 552 sequentially calculates the internal resistance R at predetermined minute time intervals, or calculates the internal resistance R in response to a request from the control unit 6 and outputs the calculation result to the control unit 6. The internal resistance Rn and the internal resistance R of the entire fuel cell stack 1 are calculated by the following equations.

  The arithmetic unit 550 is realized by an analog arithmetic circuit using an analog arithmetic IC, for example. By using the analog arithmetic circuit, it is possible to output a temporally continuous change in resistance value to the control unit 6.

  The control unit 6 receives the internal resistance R output from the calculation unit 550. The control unit 6 controls the operating state of the fuel cell stack 1 according to the magnitude of the internal resistance R.

  For example, when the internal resistance R is high, the control unit 6 determines that the electrolyte membrane 111 of the fuel cell stack 1 is in a dry state, and reduces the flow rate of the cathode gas supplied to the fuel cell stack 1. Thereby, the amount of water taken out from the fuel cell stack 1 can be reduced.

  FIG. 8 is a flowchart showing an example of an equipotential control method by the impedance measuring device 5.

  In step S <b> 1, the positive power source unit 531 outputs a constant alternating current I <b> 1 to the positive terminal 211 of the fuel cell stack 1 via the direct current cut unit 511. And the positive electrode side detection part 521 detects the alternating current potential difference V1 which arises in the internal resistance R1 between the positive electrode terminal 211 and the halfway point terminal 213 by the fixed alternating current I1.

  In step S2, the AC adjustment unit 540 sets the detection signal of the AC potential difference V1 output from the positive electrode side detection unit 521 to a reference value (target value) Vs that matches the AC potentials generated at the positive electrode terminal 211 and the negative electrode terminal. To do. The reference value Vs is a value serving as a reference for making the positive-side AC potential Va and the negative-side AC potential Vb coincide with each other.

  In step S <b> 3, the negative power supply unit 532 outputs the alternating current I <b> 2 whose amplitude is increased or decreased to the negative terminal 212 of the fuel cell stack 1 via the direct current blocking unit 512. And the negative electrode side detection part 522 detects the alternating current potential difference V2 which arises in the internal resistance R2 between the negative electrode terminal 212 and the halfway point terminal 213 by alternating current I2. Further, the current detection circuit 5325 of the negative power supply unit 532 outputs a detection signal of the alternating current I2 to the calculation unit 550.

  In step S4, the AC adjustment unit 540 determines whether the detection signal of the AC potential difference V2 output from the negative electrode side detection unit 522 is larger than the detection signal of the AC potential difference V1 that is the reference value Vs.

  In step S5, the AC adjustment unit 540 decreases the amplitude of the AC current I2 output from the negative power supply unit 532 when the detection signal of the AC potential difference V2 is larger than the detection signal of the AC potential difference V1. As a result, the AC potential Vb on the negative electrode side increases.

  In step S6, the AC adjusting unit 540 determines whether or not the detection signal of the AC potential difference V2 is equal to the detection signal of the AC potential difference V1 that is the reference value Vs.

  In step S7, the AC adjustment unit 540 determines that the AC potential Va and the AC potential Vb match when the detection signal of the AC potential difference V2 becomes equal to the detection signal of the AC potential difference V1, and therefore the AC current I2 Keep the amplitude of without adjusting. As a result, the negative side AC potential Vb is maintained.

  In step S8, when the detection signal of the AC potential difference V2 is equal to the detection signal of the AC potential difference V1, the calculation unit 550 determines that the internal resistors R1 and R2 and the internal resistances R1 and R2 and the equation (1-2) and The total internal resistance R is calculated.

  In the present embodiment, the calculation unit 550 calculates the internal resistance R1 based on the amplitude value of the alternating current I1 stored in advance and the detection signal of the alternating potential difference V1, and detects the detection signal of the alternating current I2 and the alternating potential difference V2. The internal resistance R2 is calculated based on the signal. Then, the calculation unit 550 calculates the internal resistance R of the entire fuel cell stack 1 by integrating the internal resistance R1 and the internal resistance R2.

  In step S9, the AC adjustment unit 540 determines the amplitude of the AC current I2 output from the negative power supply unit 532 when the detection signal of the AC potential difference V2 is smaller than the detection signal of the AC potential difference V1 that is the reference value Vs. Amplify. As a result, the AC potential Vb on the negative electrode side increases.

  When the processing of step S5, step S8, and step S9 is completed, the processing procedure of the control method of the impedance measuring device 5 is completed.

  Thus, by setting the detection signal of the AC potential difference V1 to the reference value Vs, the processing procedure is reduced as compared with the case where the AC potential difference V1 and the AC potential difference V2 are adjusted to a predetermined value independently of each other. The AC potential difference V1 and the AC potential difference V2 can be quickly matched.

  FIG. 9 is a time chart showing an equipotential control method of the impedance measuring device 5.

  In the initial stage of FIG. 9, the internal resistance R1 on the positive electrode side of the fuel cell stack 1 is higher than the internal resistance R2 on the negative electrode side (FIG. 9A).

  At time t0, the impedance measuring device 5 is activated (ON). Then, a constant alternating current I1 is supplied from the positive power supply unit 531 to the positive terminal 211 (FIG. 9C), and accordingly, an alternating potential difference V1 is generated in the internal resistance R1 between the positive terminal 211 and the halfway terminal 213. As a result, a detection signal of the AC potential difference V1 is output from the positive electrode side detection unit 521.

  Further, the alternating current I2 is first supplied from the negative power supply unit 532 to the negative terminal 212 with the same amplitude as the alternating current I1, and accordingly, the AC potential difference V2 is generated in the internal resistance R2 between the negative terminal 212 and the midpoint terminal 213. As a result, a detection signal of the AC potential difference V2 is output from the positive electrode side detection unit 521.

  Then, the AC adjustment unit 540 receives a detection signal of the AC potential difference V1 from the positive electrode side detection unit 521 as a reference value Vs for making the positive electrode side AC potential Va and the negative electrode side AC potential Vb coincide with each other.

  At time t0, the negative side AC potential difference V2 is lower than the positive side AC potential difference V1, which is the reference value Vs (FIG. 9B). In this state, the AC adjustment unit 540 amplifies the negative-side AC current I2 so that the AC potential difference V2 becomes the target AC potential difference V1 (FIG. 9C).

  At time t1, the AC potential difference V2 reaches the AC potential difference V1 (FIG. 9B). As a result, the potential difference between the AC potential Va on the positive electrode side and the AC potential Vb on the negative electrode side converges to almost zero, so that the AC current I1 and the AC current I2 are prevented from leaking toward the load 3.

  Then, the circuit breaker 7 is switched from the disconnected state (OFF) to the connected state (ON), and the internal resistance R1 and the internal resistance R2 are calculated based on the equation (1-1), and the internal resistance R1 and the internal resistance R2 are added. Together, the total internal resistance R is determined.

  By switching the circuit breaker 7, the wet state of the fuel cell stack 1 changes, and the internal resistance R1 decreases. Accordingly, the AC potential difference V1 decreases, and the AC adjustment unit 540 decreases the AC current I2 so that the AC potential difference V2 follows the AC potential difference V1 (FIG. 9B).

  After time t2, with the AC potential difference V2 following the AC potential difference V1 (FIG. 9B), each of the internal resistance R1 and the internal resistance R2 changes constantly (FIG. 9A). For this reason, the alternating current I1 on the positive electrode side and the alternating current I2 on the negative electrode side are kept constant (FIG. 9C).

  Next, the effect by the equipotential control of the impedance measuring apparatus 5 is demonstrated.

  FIG. 10 is a diagram illustrating a change in the positive electrode potential that occurs at the positive electrode terminal 211 of the fuel cell stack 1 and a change in the negative electrode potential that occurs at the negative electrode terminal 212.

  During output of the fuel cell stack 1, a DC voltage Vdc output from the fuel cell stack 1 to the load 3 is generated between the positive electrode terminal 211 and the negative electrode terminal 212. Before the impedance measuring device 5 is activated (ON), the positive electrode potential of the positive electrode terminal 211 and the negative electrode potential of the negative electrode terminal 212 are both constant as shown by the dotted line, which is a potential difference between the positive electrode potential and the negative electrode potential. A DC voltage Vdc is supplied to the load 3. After that, when the impedance measuring device 5 is activated and the alternating currents I1 and I2 are output from the positive power supply unit 531 and the negative power supply unit 532, the alternating current potential Va is superimposed on the positive potential and the alternating potential Vb is superimposed on the negative potential. Is done.

  The alternating current I1 output from the positive electrode side power supply unit 531 is output to the positive electrode terminal 211 of the fuel cell stack 1 through the positive electrode side direct current cut-off unit 511, and then passes through the intermediate point terminal 213 and the intermediate point direct current cut off unit 513. It is output to the positive electrode side detection unit 521. At this time, an AC potential difference V1 (= Va−Vc) is generated between the positive electrode terminal 211 and the midway terminal 213 due to a voltage drop at the internal resistance R1 by supplying the AC current I1 to the internal resistance R1. The AC potential difference V1 is detected by the positive electrode side detection unit 521.

  On the other hand, the alternating current I2 output from the negative electrode side power supply unit 532 is supplied to the negative electrode terminal 212 of the fuel cell stack 1 via the negative electrode side DC blocking unit 512 and passes through the halfway terminal 213 and the halfway DC blocking unit 513. And output to the negative electrode side detection unit 522. At this time, an AC potential difference V2 (= Vb−Vc) is generated between the negative electrode terminal 212 and the midway terminal 213 due to the voltage drop at the internal resistance R2 by supplying the AC current I2 to the internal resistance R2. The AC potential difference V2 is detected by the negative electrode side detection unit 522.

  The AC adjusting unit 540 always reduces the potential difference (V1−V2) between the AC potential difference V1 on the positive electrode side and the AC potential difference V2 on the negative electrode side, that is, the difference (Va−Vb) between the AC potential Va and the AC potential Vb. The negative-side power supply unit 532 is adjusted. As a result, the amplitude of the AC component Va having the positive potential is adjusted to be equal to the amplitude of the AC component Vb having the negative potential, so that the DC voltage Vdc is constant without being changed.

  Then, the calculation unit 550 converts the AC potential differences V1 and V2 output from the positive electrode side detection unit 521 and the negative electrode side detection unit 522 and the AC currents I1 and I2 output from the positive electrode side power supply unit 531 and the negative electrode side power supply unit 532. Apply Ohm's law based on. Thereby, the internal resistance R1 on the positive electrode side and the internal resistance R2 on the negative electrode side of the fuel cell stack 1 are calculated.

  Here, since the AC potentials of the positive electrode terminal 211 and the negative electrode terminal 212 have the same value, even if the load 3 such as a traveling motor is connected to the positive electrode terminal 211 and the negative electrode terminal 212, the AC current I1 or I2 can be prevented from leaking toward the load 3.

  Furthermore, the internal resistance R of the entire fuel cell stack 1 can be accurately measured based on the measured values of the internal resistances R1 and R2 of the operating fuel cell stack 1 regardless of the operating state of the load 3. Further, since the positive power supply unit 531 and the negative power supply unit 532 are used, the internal resistance R can be measured even when the fuel cell stack 1 is stopped.

  In the present embodiment, the example in which the amplitude of the alternating current I1 is changed without changing the amplitude of the alternating current I1 has been described. However, the amplitude of the alternating current I1 is changed to fix the amplitude of the alternating current I2. It may be. In this case, the AC adjustment unit 540 sets the detection signal of the AC potential difference V2 to the reference voltage Vs, and the AC output from the positive power supply unit 531 so that the detection signal of the AC potential difference V1 becomes the reference voltage Vs. Only the current I1 is adjusted.

  According to the first embodiment of the present invention, of the power supply units 531 and 532, the fixed power supply unit (for example, the positive power supply unit 531) that fixes the amplitude of the alternating current is one of the positive electrode terminal 211 and the negative electrode terminal 212. An alternating current having a predetermined amplitude is output to the electrode terminal (for example, the positive electrode terminal 211). Then, the variable power source (for example, the negative power source 532) that changes the amplitude of the AC current outputs an AC current having the same frequency as the AC current of the first power source to the other electrode terminal (for example, the negative terminal 212). To do.

  Of the detection units 521 and 522, the detection unit on the fixed power source side (for example, the positive electrode side detection unit 521) detects an AC potential difference between one electrode terminal (for example, the positive electrode terminal 211) and the midpoint terminal 213. Then, the variable power supply side detection unit (for example, the negative electrode side detection unit 522) detects an AC potential difference between the other electrode terminal (for example, the negative electrode terminal 212) and the midway terminal 213.

  Further, the AC adjustment unit 540 sets the AC potential difference detected by the detection unit on the variable power supply side to a reference value Vs that causes the AC potentials Va and Vb generated at the positive terminal 211 and the negative terminal 212 to coincide with each other. The AC adjustment unit 540 adjusts only the amplitude of the AC current output from the variable power supply unit so that the AC potential difference detected by the detection unit on the fixed power supply side becomes the reference value Vs.

  The calculation unit 550 calculates the internal impedance of the fuel cell stack 1 based on the AC current adjusted by the AC adjustment unit 540 and the AC potential difference generated in the fuel cell stack 1 by the AC current.

  As described above, according to the present embodiment, by setting the AC potential difference detected by the detection unit on the fixed power source side to the reference value Vs, only the AC current output from the other variable power source unit is adjusted. Both AC potential differences can be matched. For this reason, it becomes possible to fix one alternating current, and while being able to make the impedance measuring apparatus 5 a simple structure, manufacturing cost can be suppressed.

  Furthermore, according to the present embodiment, the AC potential difference V1 and the AC potential difference V2 are made to coincide with each other by a simple process compared to the case where both the AC potential difference V1 and the AC potential difference V2 are independently adjusted to a predetermined value. Can do.

  Specifically, when both the AC potential difference V1 and the AC potential difference V2 are independently adjusted to a predetermined value, the control for converging the AC potential difference V1 to a predetermined value and the AC potential difference V2 are converged to a predetermined value. Control to be executed at the same time. On the other hand, by setting the AC potential difference detected by the detection unit on the fixed power source side to the reference value Vs, only the control for causing the other AC potential difference to follow the reference value Vs is executed. The potential difference V2 can be matched.

  That is, since the number of parameters converged to the reference value Vs is reduced from two to one, a part of the adjustment function in the AC adjustment unit 540 can be omitted. For this reason, in a situation where the internal resistance R1 and the internal resistance R2 fluctuate instantaneously, the AC potential difference V1 and the AC potential difference V2 can be matched early.

  Further, when both the AC potential difference V1 and the AC potential difference V2 are independently adjusted to a predetermined value, the AC potential difference V1 becomes larger than the predetermined value due to the adjustment error, and the AC potential difference V2 is set to the predetermined value. May be smaller than the value. In this state, the adjustment error of the AC potential difference V1 and the adjustment error of the AC potential difference V2 are added and become large. On the other hand, by setting the AC potential difference detected by the detection unit on the fixed power source side as the reference value Vs, the number of parameters converged to the reference value Vs becomes one, and thus an increase in adjustment error can be suppressed. Therefore, it is possible to improve the accuracy of measuring the impedance in a situation where the internal resistance of the fuel cell stack 1 changes rapidly.

  In this way, by setting the AC potential difference detected by the detection unit on the fixed power source side as the reference value Vs, the impedance measurement accuracy can be improved and early against transient fluctuations in the internal resistances R1 and R2. The AC potential difference V1 and the AC potential difference V2 can be matched.

  Therefore, it is possible to simplify the impedance measuring device and reduce the manufacturing cost while maintaining and improving the accuracy of measuring the impedance.

  In the present embodiment, the positive power source unit 531 has a fixed power source 5311 and the negative power source unit 532 includes a voltage / current conversion circuit 5324 as a variable power source unit. In the positive electrode side detection unit 521, the first input terminal 521A is connected to the output terminal 531A of the positive electrode side power supply unit, and the second input terminal 521B is connected to the midpoint terminal 213. In the negative electrode side detection unit 522, the first input terminal 522A is connected to the output terminal 532A of the negative electrode side power supply unit, and the second input terminal 522B is connected to the midpoint terminal 213.

  In the AC adjustment unit 540, the reference terminal 540A is connected to the output terminal 531C of the positive electrode side detection unit, the input terminal 540B is connected to the output terminal 532C of the negative electrode side detection unit, and the output terminal 540C is the control terminal of the negative electrode side power supply unit. Only connected to 532B. That is, it is not connected to the positive power supply unit.

  Thereby, the control signal line wired between the AC adjustment unit 540 and the positive power supply unit 531 can be reduced, and the function of controlling the positive power supply unit 531 in the AC adjustment unit 540 can be reduced. Therefore, the configuration in the impedance measuring device 5 can be simplified.

  In the present embodiment, the negative power supply unit 532 includes a current detection circuit 5325 that detects the alternating current I2. The calculation unit 550 is connected to the output terminal 521C of the positive detection unit and the output terminal 522C of the negative detection unit. Furthermore, the amplitude value of the alternating current I1 is held in advance in the calculation unit 550, and only the current detection circuit 5325 of the negative power supply unit 532 is connected. That is, the current detection circuit 5325 is not provided in the positive power supply unit 531 having the fixed power supply 5311 but is provided only in the negative power supply unit 532 that is a variable power supply.

  Thereby, the number of detection signal lines wired between the arithmetic unit 550 and the positive power supply unit 531 can be reduced, and the circuit for detecting the alternating current I1 in the positive power supply unit 531 can be reduced. Therefore, the configuration in the impedance measuring device 5 can be simplified.

  In the present embodiment, the impedance measuring device 5 is connected between the positive-side DC blocking unit 511 connected between the positive-side power supply unit 531 and the positive-electrode terminal 211, and between the negative-side power supply unit 532 and the negative-electrode terminal 212. Negative electrode side direct current cut-off part 512. The electrostatic capacitance C1 of the positive-side DC blocking unit 511 is set to a value smaller than the electrostatic capacitance C2 of the negative-side DC blocking unit 512.

  The voltage drop Vc2 due to the negative electrode side DC blocking unit 512 is determined based on the AC current I2, the angular frequency ω, and the electrostatic capacitance C2 of the negative electrode side DC blocking unit 512 as shown in the following equation. The angular frequency ω is 2πfb, and the reference frequency fb is the frequency of the alternating current I2.

  As in the above equation, the voltage drop Vc2 caused by the negative-side DC blocking unit 512 increases as the amplitude of the alternating current I2 output from the negative-side power source unit 532 increases. Therefore, in the circuit design of the impedance measuring device 5, when the amplitude of the alternating current I2 is maximized, a combined voltage drop obtained by synthesizing the voltage drop Vr2 and the voltage drop Vc2 due to the internal resistance R2 is within the dynamic range of the circuit. Therefore, it is necessary to increase the capacitance C2 of the negative-side DC blocking unit 512 so as to be within the range.

  On the other hand, by setting the amplitude of the alternating current I1 output from the positive power supply unit 531 to, for example, a half value of the fluctuation range of the alternating current I2 output from the negative power supply unit 532, the voltage generated by the positive DC blocking unit 511 The drop Vc1 is also halved. For this reason, it is possible to reduce the electrostatic capacitance C1 of the positive-side DC blocking unit 511 as much as the voltage drop Vc1 due to the positive-side DC blocking unit 511 decreases. The smaller the capacitance, the smaller the size of the positive-side DC blocking unit 511, and thus the size of the positive-side DC blocking unit 511 can be made smaller than the negative-side DC blocking unit 512.

  Thus, by fixing the alternating current I1 output from the positive electrode side power supply unit 531, the size of the positive electrode side DC blocking unit 511 can be reduced, so that the impedance measuring device 5 can be reduced in size.

  Further, one of the power supply units 531 and 532 is connected to an electrode terminal having a large potential fluctuation among the positive electrode terminal 211 and the negative electrode terminal 212, and the other variable power supply unit is an electrode to which the fixed power supply unit is connected. It is connected to a terminal located opposite to the terminal.

  Since the variable power supply unit is feedback-controlled by the AC adjustment unit 540, it is preferably connected to an electrode terminal having a small potential fluctuation because it is susceptible to noise. On the other hand, since the fixed power supply unit is not subjected to feedback control, it is not affected by noise even when connected to an electrode terminal having a large potential fluctuation. For this reason, by connecting the fixed power supply unit to the electrode terminal that is easily affected by noise from the fuel cell stack 1, the circuit configuration associated with noise countermeasures for the detection circuit on the variable power supply unit side can be simplified.

  In this embodiment, the circuit breaker 7 that connects or disconnects between the fuel cell stack 1 and the load 3 is connected to the positive terminal 211. For this reason, the positive power source 531 having a fixed power source is connected to the positive terminal 211 via the positive DC interrupter 511, and the negative power source 532 including the variable power source is connected to the negative DC interrupter 512. To the negative electrode terminal 212.

  Even when the connection between the fuel cell stack 1 and the load 3 is interrupted by the circuit breaker 7, the positive-side power supply unit 531 is a fixed power supply, and therefore the influence of noise (potential fluctuation) by the circuit breaker 7 is not affected. I will not receive it. Therefore, it is possible to avoid failure of feedback control performed on the variable power supply unit due to noise generated when the circuit breaker 7 is disconnected.

(Second Embodiment)
FIG. 11 is a diagram showing a configuration of an impedance measuring apparatus according to the second embodiment of the present invention. Since the configuration of the impedance measuring device of the second embodiment is basically the same as the configuration of the impedance measuring device 5 shown in FIG. 2, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  The internal resistances R1 and R2 of the fuel cell stack 1 change according to the wet state of the electrolyte membrane 111. For example, when the electrolyte membrane 111 is dry, the internal resistances R1 and R2 increase. Conversely, when the electrolyte membrane 111 is sufficiently wet, the internal resistances R1 and R2 decrease.

  In the AC adjustment unit 540, since the detection signal of the AC potential difference V1 output from the positive electrode side detection unit 521 is set as the reference voltage Vs, the reference voltage Vs changes with the fluctuation of the internal resistance R1, and the reference voltage Vs becomes impedance. The dynamic range of the measuring device 5 may be exceeded. In such a case, the measurement accuracy of the internal resistance R decreases.

  As a countermeasure against this, the AC adjustment unit 540 according to the second embodiment is based on the detection signal of the AC potential difference V1, and when the AC potential difference V1 exceeds the dynamic range of the impedance measuring device 5, the amplification factor of the positive electrode side detection unit 521 and The amplification factor of the negative electrode side detection unit 522 is controlled.

  FIG. 12 is a diagram illustrating a detailed configuration of the AC adjustment unit 540. Here, a comparator 545 is provided in addition to the configuration shown in FIG.

  The comparator 545 determines whether or not the AC potential difference V1 exceeds the dynamic range of the impedance measuring device 5 based on the detection signal V1 input from the positive electrode side detection unit 521 to the reference terminal 540A.

  In the comparator 545, an upper limit threshold Th_u corresponding to the upper limit of the dynamic range of the impedance measuring device 5 and a lower limit threshold Th_d corresponding to the lower limit of the dynamic range are set.

  The upper threshold value Th_u and the lower threshold value Th_d are provided with hysteresis to avoid hunting that occurs at the boundary of the dynamic range. For example, when the dynamic range is 0.0 to 5.0 V (volts), the upper limit threshold Th_u is set to 4.5 V, and the lower limit threshold Th_d is set to 0.5 V.

  When the detection signal of the AC potential difference V1 is higher than the upper limit threshold Th_u, the comparator 545 outputs an H (High) level command signal that decreases the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522. Further, when the detection signal of the AC potential difference V1 is lower than the lower limit threshold Th_d, the comparator 545 outputs an L (Low) level command signal that increases the amplification factor of the positive electrode side detection unit 521 and the negative electrode side detection unit 522. .

  On the other hand, when the detection signal of the AC potential difference V1 is within the range from the lower limit value Th_d to the upper limit value Th_u, the comparator 545 outputs an M (Middle) level command signal between the H level and the L level. . Note that the comparator 545 may stop outputting the command signal when the detection signal of the AC potential difference V1 is within the range from the lower limit value Th_d to the upper limit value Th_u.

  FIG. 13 is a diagram illustrating the configuration of the positive electrode side detection unit 521 and the negative electrode side detection unit 522.

  The amplifier circuits 5213 and 5223 of the second embodiment are circuits that can change the amplification factor based on the command signal output from the comparator 545.

  When each of the amplifier circuits 5213 and 5223 receives the M-level command signal from the comparator 545, each of the amplifier circuits 5213 and 5223 amplifies the detection signal with a reference amplification factor.

  On the other hand, when exceeding the dynamic range of the impedance measuring device 5, when each of the amplifier circuits 5213 and 5223 receives an H-level command signal from the comparator 545, it outputs a detection signal with a predetermined amplification factor smaller than the reference amplification factor. Amplify.

  That is, when the detection signal of the alternating current V1 is larger than the dynamic range of the impedance measuring device 5, both the amplifier circuits 5213 and 5223 are switched to an amplification factor that is reduced by a predetermined amount from the reference amplification factor.

  Each of the amplifier circuits 5213 and 5223, when receiving the L level command signal from the comparator 545, amplifies the detection signal with a predetermined amplification factor larger than the reference amplification factor.

  That is, when the detection signal of the alternating current V1 is smaller than the dynamic range of the impedance measuring device 5, both the amplifier circuits 5213 and 5223 are switched to an amplification factor that is increased by a predetermined amount from the reference amplification factor.

  As described above, the AC adjustment unit 540 increases or decreases both the amplification factor of the positive electrode side detection unit 521 and the amplification factor of the negative electrode side detection unit 522 based on the detection signal of the AC current V1. As a result, even if the alternating current V1 changes due to fluctuations in the internal resistances R1 and R1 of the fuel cell stack 1, the detection signals of the alternating currents V1 and V2 can be within the dynamic range of the impedance measuring device 5. it can.

  FIG. 14 is a diagram illustrating a control method of the impedance measuring apparatus according to the present embodiment.

  In the control method of this embodiment, in addition to the series of processing from step S1 to step S9 shown in FIG. 8, processing from step S21 to step S25 is executed. Therefore, only the newly added processing from step S21 to step S25 will be described.

  In step S21, the AC adjustment unit 540 determines whether or not the detection signal of the AC potential difference V1 is higher than the upper limit threshold Th_u. The upper threshold value Th_u is set based on the upper limit of the dynamic range of the impedance measuring device 5.

  In step S22, when the detection signal of the AC potential difference V1 is higher than the upper limit threshold Th_u, the AC adjustment unit 540 decreases the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 by a predetermined amount. Specifically, AC adjustment unit 540 outputs a command signal for decreasing the amplification factor to each of amplification circuit 5213 of positive electrode side detection unit 521 and amplification circuit 5223 of negative electrode side detection unit 522. Thereby, the amplification factors of the amplifier circuit 5213 and the amplifier circuit 5223 are switched to a predetermined value smaller than a reference value.

  In step S23, the AC adjustment unit 540 determines whether or not the detection signal of the AC potential difference V1 is equal to or higher than the lower limit threshold Th_d when the detection signal of the AC potential difference V1 is equal to or lower than the upper limit threshold Th_u. The upper threshold value Th_u is set based on the lower limit of the dynamic range of the impedance measuring device 5.

  In step S24, the AC adjustment unit 540 determines that the detection signal of the AC potential difference V1 is equal to or lower than the upper limit threshold Th_u and the detection signal of the AC potential difference V1 is equal to or higher than the lower limit threshold Th_d. The amplification factor of the detection unit 522 is set to a reference value. That is, the AC adjustment unit 540 maintains the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 without increasing or decreasing when the detection signal of the AC potential difference V1 is within the dynamic range.

  In step S25, when the detection signal of the AC potential difference V1 is lower than the lower limit threshold Th_d, the AC adjustment unit 540 increases the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 by a predetermined amount. Specifically, AC adjustment unit 540 outputs a command signal for increasing the amplification factor to each of amplification circuit 5213 of positive electrode side detection unit 521 and amplification circuit 5223 of negative electrode side detection unit 522. Thereby, the amplification factors of the amplifier circuit 5213 and the amplifier circuit 5223 are switched to a predetermined value larger than a reference value.

  FIG. 15 is a diagram illustrating a method for adjusting the dynamic range of the impedance measuring apparatus 5.

  FIG. 15A shows the AC potential difference V1. In FIG. 15A, the change in AC potential difference V1 when the amplification factor is changed is indicated by a solid line, and the change in AC potential difference V1 when the amplification factor is fixed to a reference value is indicated by a broken line. For reference, the fluctuation of the internal resistance R1 of the fuel cell stack 1 is indicated by a dotted line.

  FIG. 15B is a diagram illustrating changes in the amplification factors of the positive electrode side detection units 521 and 522. The horizontal axes in FIGS. 15A and 15B are time axes common to each other.

  At time t11, the detection signal of the AC potential difference V1 is within the dynamic range of the impedance measuring device 5 as shown in FIG. 15A, and the amplification factors of the positive-side detection units 521 and 522 are shown in FIG. 15B. Is set as the reference value Ab. Thereafter, the fuel cell stack 1 is dried and the internal resistance R1 of the fuel cell stack 1 is increased.

  At time t12, the detection signal of the AC potential difference V1 becomes larger than the upper limit threshold Th_u of the dynamic range as shown in FIG. 15A, so that the positive side detection units 521 and 522 are amplified as shown in FIG. The rate is switched to a value Ad that is smaller than the reference value Ab by a predetermined amount. Thereby, since the detection sensitivity of the positive electrode side detection units 521 and 522 is lower than the reference sensitivity, the detection signal of the AC potential difference V1 can be within the dynamic range.

  Thereafter, as shown by the solid line in FIG. 15A, the internal resistance R1 stops increasing before the detection signal of the AC potential difference V1 reaches the upper limit of the dynamic range, and after the internal resistance R1 is maintained for a certain period, the fuel The internal resistance R1 is lowered by the wetting control for moistening the battery stack 1.

  At time t13, the detection signal of the AC potential difference V1 decreases by a predetermined amount from the upper limit threshold Th_u as shown in FIG. 15A, and therefore the amplification factors of the positive-side detection units 521 and 522 as shown in FIG. Is switched to the reference value Ab, and the detection sensitivity is returned to the reference sensitivity. On the other hand, the internal resistance R1 continues to decrease with time.

  At time t14, the detection signal of the AC potential difference V1 becomes smaller than the lower limit threshold Th_d of the dynamic range as shown in FIG. 15A, so that the positive side detection units 521 and 522 amplify as shown in FIG. The rate is switched to a value Au that is larger than the reference value Ab by a predetermined amount. Thereby, since the detection sensitivity of the positive electrode side detection units 521 and 522 is higher than the reference sensitivity, the detection signal of the AC potential difference V1 can be within the dynamic range.

  According to the second embodiment of the present invention, when the detection signal V1 output from the positive electrode side detection unit 521 exceeds the predetermined fluctuation range from the lower limit threshold Th_d to the upper limit threshold Th_u, the AC adjustment unit 540 The amplification factors of the side detection unit 521 and the negative side detection unit 522 are increased or decreased.

  As a result, even if the AC potential difference V1 generated by the constant AC current I1 output from the positive power supply unit 531 to the fuel cell stack 1 changes with the fluctuation of the internal resistance R1, the AC potential difference V1 is changed to the dynamics of the impedance measuring device 5. Can fit in the range.

  Therefore, the measurement accuracy of the impedance measuring device 5 is reduced as one of the power supply units 531 and 532 is a fixed power supply and the AC potential difference detected by the detection unit on the fixed power supply side is set to the reference value Vs. Can be avoided.

  In the present embodiment, the positive electrode side detection unit 521 includes extraction circuits such as a band-pass filter 5212 and a synchronous detection circuit 5214 that extract an AC component having the same frequency as the AC current I1 from the detection signal of the AC potential difference V1. Then, AC adjustment unit 540 determines whether or not AC potential difference V1 exceeds the dynamic range using the AC component extracted from the extraction circuit.

  Strong noise is likely to propagate from the load 3 to the signal lines 501 and 502. Even in a situation where such noise is mixed into the positive electrode side detection unit 521, the negative electrode side detection unit 522, and the like, the noise from the load 3 can be removed by the extraction circuit. Therefore, by using the detection signal output from the extraction circuit, the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 can be switched stably and accurately.

  In the present embodiment, the example in which the amplitude of the alternating current I1 is changed without changing the amplitude of the alternating current I1 has been described. However, the amplitude of the alternating current I1 is changed and the amplitude of the alternating current I2 is fixed. You may do it. In this case, the AC adjustment unit 540 sets the detection signal of the AC potential difference V2 to the reference voltage Vs, and the AC output from the positive power supply unit 531 so that the detection signal of the AC potential difference V1 becomes the reference voltage Vs. Only the current I1 is adjusted. Then, the AC adjustment unit 540 increases or decreases the amplification factors of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 so that the AC potential difference V2 falls within the dynamic range based on the detection signal of the AC potential difference V2.

(Third embodiment)
An impedance measuring apparatus according to a third embodiment of the present invention will be described. The configuration of the impedance measuring apparatus of the present embodiment is the same as that of the impedance measuring apparatus 5 shown in FIG.

  In the present embodiment, the AC adjusting unit 540 sets the amplitude of the AC current I1 output from the positive power supply unit 531 to a predetermined fixed value when the AC potential difference V1 exceeds the dynamic range of the impedance measuring device 5. Switch to step by step. The detailed configuration of the AC adjustment unit 540 is basically the same as the configuration shown in FIG.

  FIG. 16 is a diagram showing the configuration of the positive power supply unit 531 in the third embodiment of the present invention.

  The positive power supply unit 531 includes fixed power supplies 5311A to 5311C and a switch 5311D instead of the fixed power supply 5311 shown in FIG.

  The fixed power source 5311B outputs a DC voltage having a reference voltage value Vc_m to the switch 5311D.

  The fixed power supply 5311A outputs a DC voltage having a predetermined voltage value Vc_l smaller than the voltage value Vc_m to the switch 5311D.

  Fixed power supply 5311C outputs a DC voltage having a predetermined voltage value Vc_h larger than voltage value Vc_m to switch 5311D.

  The switch 5311D switches to one DC voltage based on the command signal output from the comparator 545 among the three DC voltages output from the fixed power sources 5311A to 5311C.

  Upon receiving the M level command signal from the comparator 545, the switch 5311D outputs the DC voltage Vc_m output from the fixed power supply 5311B to the multiplier 5323. As a result, an alternating current I1 having a reference amplitude is output from the positive power source unit 531.

  On the other hand, when exceeding the dynamic range of the impedance measuring device 5, the switch 5311 </ b> D outputs the DC voltage Vc_l output from the fixed power supply 5311 </ b> A to the multiplier 5323 when receiving the H level command signal from the comparator 545.

  That is, when the detection signal of the alternating current V1 is larger than the dynamic range of the impedance measuring device 5, the amplitude of the alternating current I1 output from the positive power supply unit 531 is decreased by a predetermined width from the reference amplitude. The amplitude can be switched.

  Further, when the switch 5311D receives the L-level command signal from the comparator 545, the switch 5311D outputs the DC voltage Vc_h output from the fixed power supply 5311C to the multiplier 5323.

  That is, when the detection signal of the alternating current V1 is smaller than the dynamic range of the impedance measuring device 5, the amplitude of the alternating current I1 output from the positive power supply unit 531 is increased by a predetermined width from the reference amplitude. The amplitude can be switched.

  As described above, the AC adjustment unit 540 increases or decreases the amplitude of the AC current I1 output from the positive power supply unit 531 based on the detection signal of the AC current V1. Thereby, even if the alternating current V1 changes with the fluctuation of the internal resistance R1 of the fuel cell stack 1, the detection signal of the alternating current V1 can be kept within the dynamic range of the impedance measuring device 5.

  FIG. 17 is a diagram illustrating a control method of the impedance measuring apparatus according to the present embodiment.

  In the control method of the present embodiment, processes of step S32, step S34, and step S35 are executed instead of the processes of step S22, step S24, and step S25 shown in FIG.

  In step S32, when the AC adjustment unit 540 determines that the detection signal of the AC potential difference V1 is higher than the upper limit threshold Th_u in step S21, the amplitude of the AC current I1 is reduced for the fixed power source of the positive power source unit 531. Switch to fixed power supply 5311A. Specifically, AC adjustment unit 540 outputs a command signal for reducing AC current I1 to switch 5311D. Thus, since the DC voltage output from the fixed power supply 5311A by the switch 5311D is input to the multiplier 5313, the amplitude of the AC current I1 output from the positive power supply unit 531 is a predetermined width than the reference amplitude. Can only be lowered.

  In step S <b> 34, when the detection signal of the AC potential difference V <b> 1 is equal to or lower than the upper limit threshold Th_u and the detection signal of the AC potential difference V <b> 1 is equal to or higher than the lower limit threshold Th_d, the AC adjustment unit 540 Is set as a reference fixed power supply 5311B. That is, the AC adjustment unit 540 maintains the AC current I1 output from the positive power supply unit 531 at a reference level when the detection signal of the AC potential difference V1 is within the dynamic range.

  In step S35, when the AC adjustment unit 540 determines that the detection signal of the AC potential difference V1 is lower than the lower limit threshold Th_d in step S23, the amplitude of the AC current I1 is increased for the fixed power source of the positive power source unit 531. Switch to fixed power supply 5311C. Specifically, AC adjustment unit 540 outputs a command signal for increasing AC current I1 to switch 5311D. Thus, since the DC voltage output from the fixed power supply 5311C by the switch 5311D is input to the multiplier 5313, the amplitude of the AC current I1 output from the positive power supply unit 531 is a predetermined width than the reference amplitude. Only raised.

  According to the third embodiment of the present invention, one of the positive power source unit 531 and the negative power source unit 532 includes the fixed power sources 5311A to 5311C that output voltages having different fixed values. An alternating current is output to the electrode terminal using one fixed power supply 5311B. When the detection signal output from the detection unit on the fixed power supply side exceeds a predetermined fluctuation range from the lower limit threshold Th_l to the upper limit threshold Th_h, the AC adjustment unit 540 uses the fixed power supply 5311B as another fixed power supply 5311A or 5311C. Switch to.

  As a result, even if the AC potential difference V1 generated by the constant AC current I1 output from the positive power supply unit 531 to the fuel cell stack 1 changes with the fluctuation of the internal resistance R1, the AC potential difference V1 is changed to the dynamics of the impedance measuring device 5. Can fit in the range.

  Accordingly, the measurement accuracy of the impedance measuring device 5 is reduced as one of the power supply units 531 and 532 is a fixed power supply unit and the AC potential difference detected by the detection unit on the fixed power supply side is set to the reference value Vs. Can be avoided.

  The positive power supply unit 531 having the fixed power supply 5311 may be configured to be connected to the electrode terminal of the internal resistance having the smaller resistance value among the internal resistances R1 and R2 of the fuel cell stack 1. The AC potential difference V1 is a product of the internal resistance R1 of the fuel cell stack 1 and the AC current I1, and the smaller the internal resistance R1, the smaller the range in which the AC potential difference V1 varies.

  For this reason, the detection sensitivity of the positive electrode side detection units 521 and 522 or the positive electrode side power supply unit can be obtained by connecting the fixed power supply unit to the electrode terminal provided on the internal resistance R1 and R2 having the smaller resistance value. The requirement for the increase / decrease amount of the alternating current I1 output from 531 can be relaxed.

  In the present embodiment, the example in which the amplitude of the alternating current I2 is changed without changing the amplitude of the alternating current I1 has been described. However, the amplitude of the alternating current I1 is changed and the amplitude of the alternating current I2 is fixed. You may do it. In this case, the AC adjustment unit 540 increases or decreases the AC current I2 output from the negative power supply unit 532 so that the AC potential difference V2 falls within the dynamic range based on the detection signal of the AC potential difference V2.

  As mentioned above, although embodiment of this invention was described, the said embodiment showed only a part of application example of this invention, and the meaning which limits the technical scope of this invention to the specific structure of the said embodiment. Absent.

  For example, in the above embodiment, the example in which the positive-current power supply unit 531 includes the voltage-current conversion circuit 5314 has been described, but the voltage-current conversion circuit 5314 may be omitted. Thereby, a fixed power supply part can be made simpler and manufacturing cost can be reduced.

  In the above embodiment, the synchronous detection circuit 5214 illustrated in FIG. 4 has described the example of extracting the real axis component of the detection signal. However, the sum of the square value of the real axis component and the square value of the imaginary axis component of the detection signal is described. The vector value may be obtained by calculating the square root of and output as the detection signal V1. Note that the imaginary axis component of the detection signal is obtained by multiplying the detection signal by an orthogonal signal whose phase is orthogonal to the alternating current I1 and smoothing the detection signal. By using the vector value, the amplitude of the AC potential difference V1 or V2 can be accurately obtained, so that equipotential control can be appropriately performed.

  Further, in the above embodiment, the calculation unit 550 has been described with respect to an example in which the internal resistance of the fuel cell stack 1 is obtained. However, in addition to the internal resistance of the fuel cell stack 1, the calculation unit 550 includes The capacitance of the fuel cell stack 1 may be calculated by obtaining the axis component.

  In the above embodiment, the example in which the internal resistance R1 is calculated using the amplitude value of the alternating current I1 recorded in the calculation unit 550 has been described. However, the current detection circuit 5325 shown in FIG. It is also possible to calculate using a detection signal from the current detection circuit. This increases the accuracy of equipotential control and improves the measurement accuracy of the internal resistance R1.

  Moreover, although the said embodiment demonstrated the example which measures the internal impedance of the fuel cell stack 1 with the impedance measuring apparatus 5, the measurement object should just be a laminated battery by which the several battery cell was laminated, for example, a laminated type The lithium ion battery may be used.

  In addition, the said embodiment can be combined suitably.

Claims (11)

First power supply means for outputting a predetermined alternating current to one of the positive electrode and the negative electrode of the laminated battery in which a plurality of battery cells are laminated;
Second power supply means for outputting an alternating current having a frequency of an alternating current output from the first power supply means to the other electrode of the positive electrode and the negative electrode;
First detection means for detecting an AC potential difference between the one electrode and the middle point of the multilayer battery;
Second detection means for detecting an AC potential difference between the other electrode and the midpoint;
The AC potential difference detected by the first detection means is set as a reference value for matching the AC potentials generated in the positive electrode and the negative electrode, and the AC potential difference detected by the second detection means becomes the reference value. Adjusting means for adjusting the alternating current output from the second power supply means;
Calculation means for calculating the impedance of the laminated battery based on the alternating current and the alternating potential difference adjusted by the adjustment means;
An impedance measuring device comprising: The impedance measuring device according to claim 1,
The first power supply means includes a fixed power supply unit,
The first input terminal of the first detection means is connected to the output terminal of the first power supply means, and the second input terminal of the first detection means is connected to the midpoint,
The second power supply means includes a variable power supply unit,
The first input terminal of the second detection means is connected to the output terminal of the second power supply means, and the second input terminal of the second detection means is connected to the midpoint,
The reference terminal of the adjusting means is connected to the output terminal of the first detecting means, and the input terminal of the adjusting means is connected to the output terminal of the second detecting means,
The output terminal of the adjusting means is connected only to the control terminal of the second power supply means.
Impedance measuring device. The impedance measuring device according to claim 2,
A current detection circuit for detecting an alternating current output from the second power supply means;
The arithmetic means holds the value of the alternating current output from the first power supply means, and is connected to the current detection circuit of the second power supply means, and the first detection means and the second detection means. Each output terminal is connected,
Impedance measuring device. The impedance measuring device according to claim 2 or 3, wherein
The variable power supply unit is
A detection circuit for detecting an alternating current output to the other electrode;
An output adjustment circuit that adjusts an alternating current output to the other electrode based on a command value output from the adjustment unit according to a detection value detected by the detection circuit;
The calculation means also uses the detection value detected by the detection circuit as the value of the alternating current output from the second power supply means.
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 4, wherein
A first DC blocking unit connected between the first power supply means and the one electrode;
A second DC blocking part connected between the second power supply means and the other electrode,
The capacitance of the first DC blocking unit is set to a value smaller than the capacitance of the second DC blocking unit.
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 5, wherein
The first detection means amplifies and outputs the detected detection signal,
The adjustment means increases or decreases the amplification factor of the first detection means when a detection signal output from the first detection means exceeds a predetermined fluctuation range due to a change in impedance of the stacked battery.
Impedance measuring device. The impedance measuring device according to claim 6,
An extraction circuit that extracts an alternating current component having the same frequency as the alternating current from the detection signal;
The adjusting means determines whether the detection signal exceeds the predetermined fluctuation range based on an alternating current component extracted from the extraction circuit.
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 7,
The first power supply means includes a plurality of fixed power supplies that output different fixed power values, outputs an alternating current to the one electrode using any one fixed power supply,
The adjustment unit switches the one fixed power source to another fixed power source when a detection signal output from the first detection unit exceeds a predetermined fluctuation range due to a variation in impedance of the stacked battery. ,
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 8,
The first power supply means is connected to an electrode provided between the positive electrode and the halfway point, and between the negative electrode and the halfway point, the electrode having the smaller impedance of the stacked battery,
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 9, wherein
The first power supply means is connected to an electrode having a large potential fluctuation among the positive electrode and the negative electrode of the stacked battery,
The second power supply means is connected to another electrode located opposite to the electrode;
Impedance measuring device. The impedance measuring device according to claim 10,
The first power supply means is connected to the electrode terminal to which a circuit breaker for connecting or breaking between the stacked battery and a load is connected.
Impedance measuring device.

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