JP6458375B2 - 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 device outputs an alternating current of the same frequency to each of the positive electrode terminal and the negative electrode terminal of the multilayer battery so that the current does not leak to the load connected to the multilayer battery. The measuring device has an AC potential difference obtained by subtracting 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 an alternating current obtained by subtracting the potential of the above halfway terminal from the potential of the negative electrode terminal. Detect potential difference. Then, the internal resistance of the laminated battery is measured based on the detected AC potential difference and the AC current output from the measuring device.

International Publication No. 2012/077450

  In the measuring apparatus as described above, a DC interrupting unit composed of a capacitor or the like is provided to interrupt the DC voltage output from the load. In order to superimpose a constant alternating current component on the positive and negative terminals of the laminated battery via the direct current blocking unit, a bipolar alternating current in which the signal varies alternately between a positive value and a negative value with 0 V (volt) as a reference. It is necessary to output a signal. For this reason, the measuring apparatus has a circuit configuration for processing a bipolar AC signal.

  For example, since the voltage fluctuation noise from the load is mixed in the measuring apparatus, an extraction circuit that extracts a signal component having the same frequency as the alternating current from the bipolar detection signal is provided. In order to process a bipolar AC signal in the extraction circuit, it is necessary to separately provide a circuit used when the AC signal is positive and a circuit used when the AC signal is negative, and the circuit configuration is complicated. become.

  As described above, there is a problem that the circuit configuration becomes complicated in the measuring apparatus that processes the bipolar AC signal.

  The present invention has been made paying attention to such problems, and an object thereof is to provide an impedance measuring apparatus that simplifies the configuration of the apparatus and suppresses the manufacturing cost.

According to an aspect of the present invention, an impedance measuring apparatus includes: a power source that outputs an alternating current to a positive electrode and a negative electrode of a stacked battery in which a plurality of battery cells are stacked; and a midpoint between the positive electrode and the stacked battery. Detecting means for detecting at least one of the AC potential difference between the negative electrode and the AC potential difference between the negative electrode and the midpoint. The impedance measuring device includes: an arithmetic unit that calculates an impedance of the stacked battery based on an AC potential difference detected by the detection unit and an AC current output from the power source unit; the power source unit and the detection unit Polarity conversion means for converting an alternating current signal processed by at least one of the means between bipolar and unipolar;
It is characterized by including.

  According to this aspect, since the bipolar conversion signal is output from the power supply means and the unipolar alternating current signal is output from the detection means by the polarity conversion means, the configuration of the apparatus is simplified. Manufacturing costs can be reduced.

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 shows a configuration of a DC blocking unit that blocks an AC signal output from the stacked battery, an AC potential difference generated between the positive electrode terminal and the midpoint terminal of the stacked battery, and the negative electrode terminal and the midpoint terminal of the stacked battery. It is a figure which shows the structure of the detection part which detects the alternating current potential difference which arises between. FIG. 4 is a diagram illustrating a configuration of a power supply unit that outputs an alternating current to the positive electrode terminal of the laminated battery. FIG. 5 is a diagram illustrating a configuration of an AC adjustment unit that adjusts an AC current output from the power supply unit to each of the positive electrode terminal and the negative electrode terminal. FIG. 6 is a diagram illustrating a configuration of a calculation unit that calculates the internal impedance of the laminated battery. FIG. 7 is a diagram showing potentials generated at the positive electrode terminal and the negative electrode terminal of the laminated battery by equipotential control. FIG. 8 is a diagram illustrating a configuration of a synchronous detection circuit including a unipolar conversion circuit according to the present embodiment. FIG. 9 is a diagram illustrating a waveform of an AC signal converted from bipolar to unipolar by the unipolar conversion circuit. FIG. 10 is a reference diagram showing a configuration of a synchronous detection circuit for processing a bipolar AC signal. FIG. 11 is a diagram illustrating an arrangement example of a unipolar conversion circuit provided in the impedance measuring apparatus. FIG. 12 is a diagram showing a configuration on the positive electrode side that also serves as a synchronous detection circuit in the second embodiment of the present invention. FIG. 13 is a diagram illustrating a configuration of a power supply unit including a bipolar conversion circuit according to the third embodiment of the present invention. FIG. 14 is a diagram illustrating a waveform of an AC signal converted from monopolar to bipolar by the bipolar converter circuit.

  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 of the impedance measuring 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 (positive) electrode (positive electrode) of the fuel cell stack 1 is provided with a positive electrode terminal 211, and a current collecting plate corresponding to a negative (minus) electrode (negative electrode) of the fuel cell stack 1. 20 is provided with a negative electrode terminal 212. 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 midpoint terminal 213 is provided in the power generation cell 10 that is midway between the positive terminal 211 and the negative terminal 212. In the present embodiment, the midpoint terminal 213 is provided in the power generation cell 10 located in the middle (midpoint) among the plurality of power generation cells 10 stacked from the positive electrode terminal 211 to the negative electrode terminal 212. Note that the midpoint terminal 213 may be positioned away from the midpoint between the positive terminal 211 and the negative 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 metal separator base 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 an electric load such as an electric motor or an auxiliary machine used for power generation of the fuel cell stack 1. The auxiliary machine connected to the fuel cell stack 1 heats, for example, a compressor for supplying cathode gas to the fuel cell stack 1 or cooling water flowing through the fuel cell stack 1 when the fuel cell stack 1 is warmed up. For heaters.

  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 flow rate of the cathode gas and the anode gas supplied to the fuel cell stack 1 according to the generated power required 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 to control the gas flow rate 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 order to maintain the power generation performance of the fuel cell stack 1. In the present embodiment, the impedance measuring device 5 measures the internal resistance of the fuel cell stack 1 and transmits the measured value to the control unit 6. When the control unit 6 receives the measured value of the internal resistance of the fuel cell stack 1 from the impedance measuring device 5, the control unit 6 controls the wet state of the fuel cell stack 1 based on the measured value.

  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.

  The positive-side DC blocking unit 511, the negative-side DC blocking unit 512, and the midpoint DC blocking unit 513 are DC blocking units that block DC signals but pass AC signals. The positive-side DC blocking unit 511 and the negative-side DC blocking unit 512 are DC blocking units that allow an AC signal output from the positive terminal 211 and the negative terminal 212 to the positive detection unit 521 and the negative detection unit 522 to pass therethrough.

  Each of the DC blocking units 511 to 513 is realized by, for example, a capacitor or a transformer. In addition, about the halfway point DC interruption | blocking part 513 shown with the broken line, it is omissible.

  The positive electrode side detection unit 521 and the negative electrode side detection unit 522 are at least one of the alternating current potential difference between the positive electrode terminal 211 and the halfway point terminal 213 and the alternating current potential difference between the negative electrode terminal 212 and the halfway point terminal 213. Detection means for detecting a potential difference.

  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 component of the potential generated at the positive terminal 211 and an AC potential Vc that is an AC component of the potential generated at the midpoint terminal 213. ") Is detected.

  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 is connected to the positive electrode terminal 211 via the DC blocking unit 511, the second input terminal is grounded, and the output terminal is connected to both the AC adjustment unit 540 and the calculation unit 550. Is done.

  The negative electrode side detection unit 522 has a potential difference (hereinafter referred to as “AC potential difference V2”) between an AC potential Vb that is an AC component of the potential generated at the negative terminal 212 and an AC potential Vc that is an AC component of the potential generated at the midpoint terminal 213. ) Is detected.

  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 is connected to the negative electrode terminal 212 through the DC blocking unit 512, the second input terminal is grounded, and the output terminal is connected to both the AC adjustment unit 540 and the calculation unit 550. Is done.

  Here, details of the positive side DC blocking unit 511, the negative side DC blocking unit 512, the midpoint DC blocking unit 513, the positive side detection unit 521, and the negative side detection unit 522 will be described with reference to FIG.

  The positive-side DC blocking unit 511 includes a capacitor 511 </ b> A connected between the positive terminal 211 of the fuel cell stack 1 and the output terminal of the positive-side power supply unit 531, and the first input terminal of the positive terminal 211 and the positive-side detection unit 521. And a capacitor 511B connected between the two.

  The negative-side DC blocking unit 512 includes a capacitor 512 </ b> A connected between the negative-electrode terminal 212 of the fuel cell stack 1 and the output terminal of the negative-side power supply unit 532, and the second input terminal of the negative-electrode terminal 212 and the negative-side detection unit 522. And a capacitor 512B connected between the two.

  The midpoint DC blocking unit 513 includes a capacitor 513 </ b> A connected between the midpoint terminal 213 of the fuel cell stack 1 and the second input terminal of the positive electrode side detection unit 521, and the midpoint terminal 213 and the negative electrode side detection unit 522. And a capacitor 513B connected between the first input terminal.

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

  The potential difference detection circuit 5211 outputs a detection signal obtained by subtracting the potential Vc from the AC potential Va. The AC potential Va is a signal component that passes through the capacitor 511B in the signal output from the positive terminal 211, and the potential Vc is a signal component that passes through the capacitor 513A in the signal output from the midway terminal 213. is there. The potential difference detection circuit 5211 is realized by a differential amplifier.

  Voltage fluctuation noise is mixed in the potential difference detection circuit 5211 from the load 3 through the positive terminal 211. The noise from the load 3 has a wide frequency distribution and the noise level is about three orders of magnitude greater than the AC potential difference V1. For this reason, the detection signal output from the potential difference detection circuit 5211 includes an unnecessary signal output from the load 3.

  The band-pass filter 5212 removes unnecessary signals included in the detection signal and passes only signal components in a frequency band necessary for detection. Specifically, the band-pass filter 5212 passes a signal component having the same frequency as the frequency of the alternating current I1 in the detection signal output from the potential difference detection circuit 5211, and removes signal components in other frequency bands. .

  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 in consideration of the dynamic range of the impedance measuring device 5.

  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 as the alternating current I1 and having the same phase as that of the alternating current I1, and multiplies the multiplied alternating detection signal. It is converted into a DC detection signal V1 by smoothing. The smoothed detection signal V1 changes according to the amplitude of the AC potential difference V1.

  As described above, the positive electrode side detection unit 521 generates a detection signal proportional to the amplitude of the AC potential difference V1, and removes unnecessary signals by the band-pass filter 5212 and the synchronous detection circuit 5214. The detection signal V1 is output to the AC adjustment unit 540 and the calculation unit 550.

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

  Next, the configuration of the positive power supply unit 531 and the negative power supply unit 532 will be described.

  The positive power supply unit 531 and the negative power supply unit 532 are power supply units that output AC signals having the same frequency to both of the positive electrode terminal 211 and the negative electrode terminal 212 of the fuel cell stack 1.

  The positive power supply unit 531 supplies an alternating current I1 having a reference frequency fb determined for measuring the internal impedance of the fuel cell stack 1 to the positive terminal 211 of the fuel cell stack 1 via the positive DC blocking unit 511. Output. The amplitude of the alternating current I1 output from the positive power supply unit 531 is controlled by the alternating current adjustment unit 540. The positive power supply unit 531 is realized by a voltage-current conversion circuit including an operational amplifier (OA), for example.

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

  The positive power supply unit 531 includes a voltage / current conversion circuit 5311 and a synchronous detection circuit 5312.

  The voltage-current conversion circuit 5311 converts the AC voltage Vi1 having the reference frequency fb into an AC current I1, and outputs the AC current I1 to the positive-side DC cutoff unit 511. The AC voltage Vi1 is a current command signal output from the AC adjustment unit 540 to the positive power supply unit 531.

  The voltage-current conversion circuit 5311 includes an operational amplifier OA1 that outputs an alternating current I1 based on the alternating voltage Vi1, a detection resistance element Rs, and an operational amplifier OA2 that adjusts the alternating current I1 according to the detection voltage Vi1s generated in the detection resistance element Rs. And resistance elements R1 to R5.

  The operational amplifier OA1 outputs an alternating current I1 that is proportional to the alternating voltage Vi1. The non-inverting input terminal of the operational amplifier OA1 is connected to the positive terminal of the AC adjustment unit 540, 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 magnitude of the alternating current I1 output from the operational amplifier OA1. 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 capacitor 511A.

  The detection voltage Vi1s generated at both ends of the detection resistance element Rs is a value obtained by multiplying the current value of the alternating current I1 and the resistance value of the detection resistance element Rs, and is proportional to the magnitude of the alternating current I1.

  The operational amplifier OA2 is current detection means for detecting the magnitude of the detection voltage Vi1s generated in the detection resistance element Rs. The detection signal Vi1s output from the operational amplifier OA2 is fed back to the inverting input terminal of the operational amplifier OA1. The operational amplifier OA1 increases or decreases the alternating current I1 according to the detection signal Vi1s. Thereby, the amplitude of the alternating current I1 is adjusted to be proportional to the amplitude of the alternating voltage Vi1.

  The resistance values of the resistance elements R1 to R5 are appropriately set according to the design of the impedance measuring device 5.

  The synchronous detection circuit 5312 extracts only a signal component having the same frequency fb and the same phase as the alternating current I1 from the detection signal in order to remove an unnecessary signal included in the detection signal Vi1s output from the operational amplifier OA2. It is. The configuration of the synchronous detection circuit 5312 is the same as that of the synchronous detection circuit 5214 shown in FIG.

  The synchronous detection circuit 5312 outputs the detection signal I1 from which the unnecessary signal is removed to the arithmetic unit 550. The detection signal I1 output from the synchronous detection circuit 5312 is a direct current signal proportional to the amplitude of the alternating current I1.

  Thus, the positive power supply unit 531 outputs the alternating current I1 based on the command signal output from the alternating current adjustment unit 540. Further, the magnitude of the alternating current I1 is detected by the detection resistor element Rs and the operational amplifier OA2, and the detection signal I1 from which unnecessary signals are removed by the synchronous detection circuit 5312 is output to the arithmetic unit 550.

  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 of the fuel cell stack 1 via the negative DC blocking unit 512. The amplitude of the alternating current I2 output from the negative power supply unit 532 is controlled by the alternating current adjustment unit 540. Note that the configuration of the negative power supply unit 532 is the same as that of the positive power supply unit 531, and therefore detailed description thereof is omitted here.

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

  The AC adjustment unit 540 outputs AC from at least 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. It is an adjusting means for adjusting the amplitude and phase of the current.

  In the present embodiment, the AC adjustment unit 540 adjusts the amplitude of the AC current I1 output from the positive power supply unit 531 and the amplitude of the AC current I2 output from the negative power supply unit 532, respectively. The AC adjustment unit 540 is realized by, for example, a PI (Proportional Integral) control circuit.

  The AC adjustment unit 540 includes a positive electrode side subtractor 5411, a positive electrode side integration circuit 5421, a positive electrode side multiplier 5431, a negative electrode side subtractor 5412, a negative electrode side integration circuit 5422, and a negative electrode side multiplier 5432. Further, the AC adjustment unit 540 includes a reference power source 545 and an AC signal source 546.

  The reference power source 545 outputs a voltage (hereinafter referred to as “reference voltage Vs”) set with 0 V (volt) as a reference in order to match the positive-side AC potential difference V1 with the negative-side AC potential difference V2. . The reference voltage Vs is a value determined by experiments or the like.

  The AC signal source 546 is an oscillation source that oscillates an AC signal having the reference frequency fb. The reference frequency fb is set to a predetermined 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 positive-side subtractor 5411 outputs a difference signal proportional to the deviation width from the reference voltage Vs by subtracting the reference voltage Vs from the detection signal V1 output from the positive-side detection unit 521. For example, the difference signal level increases as the deviation width from the reference voltage Vs increases.

  The positive-side integrating circuit 5421 integrates the difference signal output from the positive-side subtractor 5411 to thereby average the difference signal or adjust the sensitivity. Then, the positive side integration circuit 5421 outputs the integrated difference signal to the positive side multiplier 5431.

  The positive-side multiplier 5431 generates an AC voltage Vi1 that converges the amplitude of the AC potential difference V1 to the reference voltage Vs by multiplying the AC signal of the reference frequency fb output from the AC signal source 546 by the difference signal. . For example, the amplitude of the AC voltage Vi1 increases as the level of the difference signal output from the positive-side subtractor 5411 increases.

  The positive multiplier 5431 outputs the AC voltage Vi1 to the positive power supply 531 as a current command signal. The AC voltage Vi1 is converted into an AC current I1 by the positive power supply unit 531.

  Note that the negative-side subtractor 5412, the negative-side integrating circuit 5422, and the negative-side multiplier 5432 have the same configurations as the positive-side subtracter 5411, the positive-side integrating circuit 5421, and the positive-side multiplier 5431, respectively. The description about is omitted.

  As described above, the AC adjustment unit 540 adjusts the amplitude of the AC current I1 output from the positive power supply unit 531 so that the amplitude of the AC potential difference V1 becomes the reference voltage Vs. Similarly, the AC adjustment unit 540 adjusts the amplitude of the AC current I2 output from the negative power supply unit 532 so that the amplitude of the AC potential difference V2 becomes the reference voltage Vs.

  As a result, the AC potential Va and the AC potential Vb are controlled to the same level, so that the AC potential Va superimposed on the positive electrode terminal 211 matches the AC potential Vb superimposed on the negative electrode 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 alternating currents I1 and I2 adjusted by the AC adjustment unit 540 and the amplitudes of the AC potential differences V1 and V2.

  The calculation unit 550 receives detection signals indicating the amplitudes of the AC potential differences V1 and V2 from the positive electrode side detection unit 521 and the negative electrode side detection unit 522, and receives alternating currents I1 and I2 from the positive electrode side power supply unit 531 and the negative electrode side power supply unit 532. A detection signal indicating the amplitude of is input.

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

  The AD converter 551 converts the detection signals of the alternating currents I1 and I2 and the detection signals of the alternating potential differences V1 and V2 into digital numerical signals and transfers them to the microcomputer chip 552.

  The microcomputer chip 552 stores a program for calculating the internal resistance Rn of the fuel cell stack 1 and the internal resistance R of the entire fuel cell stack 1 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 of the fuel cell stack 1 and the internal resistance R of the entire fuel cell stack 1 are calculated by the following equations.

  The calculation unit 550 is realized by an analog calculation circuit including an analog calculation 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.

  When the control unit 6 receives the internal resistance R output from the calculation unit 550, the control unit 6 controls the operation 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.

  Next, the effect of the equipotential control by the impedance measuring device 5 will be described.

  FIG. 7 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 equal to the amplitude of the AC component Vb having the negative potential, so that the DC voltage Vdc is constant without fluctuation.

  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 impedance measuring device 5, a positive side DC blocking unit 511 is provided between the positive terminal 211 and the positive side power supply unit 531, and a negative side DC blocking unit 512 is provided between the negative terminal 212 and the negative side power supply unit 532. Is provided.

  For this reason, in order to superimpose the AC potentials Va and Vb at a certain level on each of the positive electrode terminal 211 and the negative electrode terminal 212, it is necessary to output a bipolar AC signal to the DC blocking units 511 and 512.

  A bipolar AC signal is an AC signal in which the signal changes alternately between a positive (plus) value and a negative (minus) value with 0V as a reference. If an alternating current signal that changes based on a value higher than 0V is output to the direct current interrupter 511, the direct current component of the alternating current signal is higher than 0V, so that charge is accumulated in the direct current interrupter 511 and becomes saturated. An AC signal is not transmitted from the unit 511 to the positive terminal 211.

  On the other hand, if the internal circuit of the impedance measuring device 5 is configured to process a bipolar AC signal, the circuit that processes the signal when the AC signal is positive and the signal when the AC signal is negative. It is necessary to provide the circuit separately, and the configuration of the internal circuit becomes complicated.

  Therefore, in the present embodiment, the AC detection signal input to the synchronous detection circuit 5214 of the positive electrode side detection unit 521 and the detection signal input to the synchronous detection circuit 5312 of the positive electrode side power supply unit 531 are converted from bipolar to unipolar. To do. A unipolar AC signal is an AC signal that changes around a reference value while the signal is either positive or negative.

  FIG. 8 is a diagram showing a configuration of the synchronous detection circuit 5214 in the present embodiment.

  The synchronous detection circuit 5214 includes a unipolar conversion circuit 410, a signal multiplication circuit 420, and a signal extraction filter 430.

  The unipolar conversion circuit 410 is polarity conversion means for converting a bipolar AC signal into a unipolar AC signal.

  In the present embodiment, the unipolar conversion circuit 410 converts the detection signal output from the amplifier circuit 5213 from a bipolar AC signal to a unipolar AC signal. The unipolar conversion circuit 410 includes a capacitor 411, a reference potential line 412, and a resistance element 413.

  The capacitor 411 is used to convert the center of the amplitude of the AC signal from 0 V to the reference potential (Vo / 2). One electrode of the capacitor 411 is connected to the output terminal of the amplifier circuit 5213, and the other electrode is connected to the input terminal of the signal multiplier circuit 420.

  The reference potential line 412 is a signal line to which a DC reference potential (Vo / 2) is supplied from a power source (not shown). The reference potential (Vo / 2) is set to a value that is half the amplitude of the AC signal output from the amplifier circuit 5213.

  The resistance element 413 is provided to superimpose a reference potential (Vo / 2) on the other electrode of the capacitor 411. One end of the resistance element 413 is connected to the reference potential line 412, and the other end of the resistance element 413 is connected to the other electrode and the input terminal of the signal multiplication circuit 420.

Thus, in the unipolar conversion circuit 410, when a bipolar AC signal is input to one electrode of the capacitor 411, an AC signal having the same waveform is propagated to the other electrode, and the resistance element 413 A DC reference potential (Vo / 2) is superimposed. As a result, a unipolar AC signal is generated and input to the signal multiplication circuit 420.

The signal multiplication circuit 420 converts the phase of the detection signal output from the unipolar conversion circuit 410 into an AC signal of the reference frequency fb (hereinafter referred to as “reference signal”) output from the AC signal source 546 shown in FIG. Based on this, a full-wave rectified waveform is generated by shifting 180 degrees.

Specifically, the signal multiplying circuit 420, an AC signal source when the reference signal 546 is positive is shifted by 180 degrees the phase of the detection signal, the detection signal when the reference signal of the AC signal source 546 is negative phase Is not shifted , full-wave rectification waveform processing is applied to the detection signal.

Signal multiplier circuit 420 includes a resistive element 421-4 23, a transistor 424, an operational amplifier 425, a comparator 426.

  The resistance element 421 is connected between the output terminal of the unipolar conversion circuit 410 and the inverting input terminal (−) of the operational amplifier 425, and the resistance element 422 is the non-inverting input of the unipolar conversion circuit 410 and the operational amplifier 425. Connected to terminal (+).

  The resistance element 423 is connected between the inverting input terminal (−) of the operational amplifier 425 and the output terminal of the operational amplifier 425. The resistance value of the resistance element 423 is set to the same value as the resistance value of the resistance element 421.

  The transistor 424 is connected between the non-inverting terminal (+) of the operational amplifier 425 and a grounded ground line. In the present embodiment, the transistor 424 is a field effect transistor (FET), the drain (D) of the transistor 424 is connected to the non-inverting terminal (+) of the operational amplifier 425, and the source (S) of the transistor 424. Is connected to the ground wire.

  The gate (G) of the transistor 424 is connected to a comparator 426 that supplies a detection signal for detecting a signal component having the same frequency fb as that of the alternating current I1. The detection signal is a rectangular pulse signal generated based on the reference signal output from the AC signal source 546 shown in FIG. For example, a 5V (volt) pulse signal is output when the reference signal is positive, and a 0V pulse signal is output when the reference signal is negative.

  The transistor 424 connects or blocks between the non-inverting terminal (+) of the operational amplifier 425 and the ground line according to the detection signal output from the comparator 426. That is, the transistor 424 switches the non-inverting terminal (+) of the operational amplifier 425 to the ground state (conduction state) or the non-ground state (non-conduction state) based on the reference signal output from the AC signal source 546.

  A unipolar AC signal output from the unipolar conversion circuit 410 is input to the inverting input terminal (−) and the non-inverting input terminal (+) of the operational amplifier 425.

  The operational amplifier 425 shifts the phase of the unipolar AC signal output from the unipolar conversion circuit 410 by 0 degree or 180 degrees based on the reference signal output from the AC signal source 546.

  In the operational amplifier 425, when the reference signal of the AC signal source 546 is positive, the transistor 424 becomes conductive and the non-inverting input terminal (+) becomes 0 V. Therefore, the AC signal input to the inverting input terminal (−) is inverted. The output signal is output.

  On the other hand, when the reference signal of the AC signal source 546 is negative, the transistor 424 becomes non-conductive and the non-inverting input terminal (+) and the inverting input terminal (−) have the same potential. A non-inverted AC signal is output.

  The signal extraction filter 430 smoothes the detection signal that has been subjected to the full-wave rectification waveform processing by the signal multiplication circuit 420. The signal extraction filter 430 is realized by, for example, a low-pass filter (LPF).

  In the present embodiment, the signal extraction filter 430 is a low-pass filter composed of a resistance element 131 and a capacitor 132.

  One end of the resistance element 131 is connected to the output terminal of the operational amplifier 425, the other end of the resistance element 131 is connected to one electrode of the capacitor 132, and the other electrode of the capacitor 132 is grounded.

  Thus, the detection signal output from the signal multiplication circuit 420 is converted into a DC detection signal V1. The converted detection signal V1 is a signal proportional to the amplitude of the AC potential difference V1, and for example, the level of the detection signal V1 increases as the amplitude of the AC potential difference V1 increases.

  FIG. 9 is a diagram illustrating an AC signal converted by the unipolar conversion circuit 410.

  Bipolar alternating current signal that changes between positive and negative around 0V by the unipolar conversion circuit 410 has a minimum value of zero, and the unipolar that changes on the positive side around the reference potential (Vo / 2) Is converted into an AC signal.

  As described above, the unipolar conversion circuit 410 is arranged closer to the potential difference detection circuit 5211 than the signal multiplication circuit 420, whereby the AC signal input to the signal multiplication circuit 420 is converted from bipolar to unipolar. Therefore, in the signal multiplication circuit 420, a signal output from the operational amplifier 425 can be formed into a full-wave rectified waveform by one transistor 424. That is, the signal multiplication circuit 420 can be configured simply.

  Although the configuration of the synchronous detection circuit 5214 has been described with reference to FIG. 8, other synchronous detection circuits provided in the impedance measuring device 5 can be configured as simple as the synchronous detection circuit 5214. For example, for the synchronous detection circuit 5224 of the negative electrode side detection unit 522 and the synchronous detection circuits 5314 of the positive electrode side power supply unit 531 and the negative electrode side power supply unit 532, the unipolar conversion circuit 410, the signal multiplication circuit 420, and the signal extraction filter 430 are provided. Contain the configuration.

  As a result, the number of transistors used in the signal multiplication circuit 420 can be reduced, so that the impedance measuring device 5 can be downsized and the manufacturing cost can be reduced.

  Note that although an example in which an FET is used as the transistor 424 has been described in this embodiment, the present invention is not limited to this. For example, a bipolar transistor may be used as the transistor 424. In this case, the collector (C) is connected to the non-inverting terminal (+) of the operational amplifier 425, the emitter (E) is connected to the ground line, and the base (B) is connected to the comparator 426.

  In the present embodiment, the example in which the unipolar conversion circuit 410 is disposed between the amplifier circuit 5213 and the signal multiplication circuit 420 has been described. However, the unipolar conversion circuit 410 is located at the DC blocking units 511 and 512 and the signal multiplication circuit. It may be between 420.

  FIG. 10 is a diagram illustrating an arrangement example of the unipolar conversion circuit 410. Here, the unipolar conversion circuit 410 of the synchronous detection circuit 5214 shown in FIG. 3 is arranged between the positive-side DC blocking unit 511 (or the capacitor 511B) and the first input terminal of the positive-side detection unit 521. Furthermore, the unipolar conversion circuit 410 of the synchronous detection circuit 5224 is disposed between the negative-side DC blocking unit 512 (or the capacitor 512B) and the first input terminal of the negative-side detection unit 522.

  In this way, the unipolar conversion circuit 410 is connected between the positive-side DC cutoff unit 511 and the signal multiplication circuit 420 of the positive-side detection unit 521 or between the negative-side DC cutoff unit 512 and the negative-side detection unit 522. Since the signal input to the signal multiplier circuit 420 is converted into a unipolar AC signal, the configuration of the signal multiplier circuit 420 can be simplified.

  According to the first embodiment of the present invention, the power supply means configured by the positive power supply unit 531 and the negative power supply unit 532 outputs alternating currents I1 and I2 to the positive electrode 211 and the negative electrode 212 of the stacked battery 1. . The detection means configured by at least one of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 includes an AC potential difference V1 between the positive electrode 211 and the intermediate point 213 of the stacked battery 1, and between the negative electrode 212 and the intermediate point 213. At least one of the AC potential differences V2 is detected. The calculation means configured by the calculation unit 550 calculates the impedance of the laminated battery 1 based on the AC potential difference detected by the detection means and the AC current output from the power supply means.

  And the polarity conversion means comprised including the unipolar conversion circuit 410 converts the alternating current signal processed by at least one of a power supply means and a detection means between bipolar and unipolar. In the first embodiment, the polarity conversion unit converts an AC signal indicating an AC potential difference detected (processed) by the detection unit from bipolar to unipolar.

  As described above, according to the present embodiment, the polarity conversion means outputs the bipolar AC signal from the power supply means and the unipolar AC signal from the detection means. Can be simplified and the manufacturing cost can be suppressed.

  Further, in the present embodiment, the impedance measuring device 5 includes DC blocking means configured by DC blocking units 511 and 512 that pass AC signals output from the positive terminal 211 and the negative terminal 212 to the detection units 521 and 522, respectively. . Further, an extraction constituted by a signal multiplication circuit 420 for extracting a signal component of the same frequency fb from the AC signal indicating the AC potential difference V1 output from the detection means based on the reference signal having the same frequency fb as the AC current I1. Includes circuitry.

  The unipolar conversion circuit 410 is connected between the DC cutoff means and the extraction circuit, and converts a bipolar AC signal output from the DC cutoff means into a unipolar AC signal. For example, the unipolar conversion circuit 410 is disposed between the capacitor 511 </ b> B and the first input terminal of the potential difference detection circuit 5211 illustrated in FIG. 3 or between the potential difference detection circuit 5211 and the signal multiplication circuit 420.

  Thereby, the circuit configuration of at least one signal multiplication circuit 420 of the positive electrode side detection unit 521 and the negative electrode side detection unit 522 can be simplified.

  Further, in the present embodiment, the adjusting means configured by the AC adjusting unit 540 is an AC output from the power supply means to at least one of the positive electrode 211 and the negative electrode 212 so that the AC potential difference V1 and the AC potential difference V2 coincide. Adjust the current. And the current detection means comprised by the detection resistance element Rs shown in FIG. 4 and operational amplifier OA2 detects the alternating current I1 output from a power supply means. Further, the extraction circuit composed of the signal multiplication circuit 420 of the synchronous detection circuit 5314 has the same frequency fb included in the AC signal V1 output from the current detection means based on the reference signal having the same frequency fb as the AC current I1. Extract signal components.

  The unipolar conversion circuit 410 is connected between the output terminal of the operational amplifier OA2 and the signal multiplication circuit 420, and converts a bipolar AC signal output from the current detection means into a unipolar AC signal.

  Thereby, the configuration of at least one of the signal multiplying circuit 420 of the positive power supply unit 531 and the negative power supply unit 532 can be simplified.

  In the present embodiment, the extraction circuit including the signal multiplication circuit 420 includes a transistor 424 and an operational amplifier 425. The operational amplifier 425 has a non-inverting input terminal (+) to which a unipolar AC signal is input, and an inverting input terminal (−) to which the same unipolar AC signal as the non-inverting input terminal (+) is input. The transistor 424 connects or disconnects between the non-inverting input terminal (+) of the operational amplifier 425 and the ground terminal based on the reference signal having the same frequency fb as the alternating current I1. Accordingly, the AC signal output from the operational amplifier 425 is rectified by the transistor 424.

  In this way, by inputting a unipolar AC signal to each of the non-inverting input terminal (+) and the inverting input terminal (−) of the operational amplifier 425, a circuit and an AC signal required when the AC signal is positive can be obtained. There is no need to provide a circuit that is necessary when negative. That is, since the circuit used when the AC signal is negative can be omitted, the configuration of the extraction circuit can be simplified.

  FIG. 11 is a reference diagram illustrating a configuration of the switch circuit 910 used in the signal multiplication circuit 900 to which a bipolar AC signal is input.

  Switch circuit 910 includes an Nch transistor, a Pch transistor, and a drive circuit D.

  When the AC signal input to the signal multiplication circuit 900 is positive, a positive pulse signal Vg is supplied from the drive circuit D to the gate (G) of the Nch transistor so that the non-inverting terminal (+) of the operational amplifier 425 is grounded. Is done.

  Further, when the AC signal input to the signal multiplication circuit 900 is negative, the drive circuit D to the gate (G) of the Pch transistor so that the negative voltage V− is applied to the non-inverting terminal (+) of the operational amplifier 425. Is supplied with a negative pulse signal Vg.

Thus the switch circuit 910 for detection processing synchronize AC signal dipolar, requires Pch transistor in addition to the Nch transistor, further drive for switching a pulse signal Vg between positive and negative Circuit D is required.

  On the other hand, the signal multiplication circuit 420 shown in FIG. 8 can be processed by using only one transistor 424 instead of the switch circuit 910 so that the AC signal becomes a full-wave rectified waveform, so that the circuit configuration can be reduced in size. And manufacturing cost can be reduced.

(Second Embodiment)
Next, the configuration of the impedance measuring apparatus according to the second embodiment of the present invention will be described. The configuration of the impedance measuring apparatus according to the present embodiment is basically the same as the configuration of the impedance measuring apparatus 5 shown in FIG.

  In the present embodiment, the synchronous detection circuit 5214 shown in FIG. 3 is omitted in the positive electrode side detection unit 521, and the synchronous detection circuit 5312 shown in FIG. 4 is omitted in the positive electrode side power supply unit 531. Instead of these synchronous detection circuits 5214 and 5312, a synchronous detection circuit is provided in the AC adjustment unit 540.

  FIG. 12 is a diagram illustrating a configuration of the AC adjustment unit 540 according to the second embodiment of the present invention. Here, only the configuration on the positive electrode side is shown.

  The AC adjustment unit 540 of the present embodiment includes a synchronous detection circuit 5401, a switching circuit 5402, and a switching signal generator 5043 in addition to the configuration of the AC adjustment unit shown in FIG.

  The synchronous detection circuit 5401 has the same configuration as the synchronous detection circuit 5214 shown in FIG. 8 and includes a unipolar conversion circuit 410, a signal multiplication circuit 420, and a signal extraction filter 430.

  The switching circuit 5402 is switching means that is necessary for the synchronous detection circuit 5401 to be shared by the positive electrode side detection unit 521 and the positive electrode side power supply unit 531.

  The switching circuit 5402 switches the bipolar AC signal input to the synchronous detection circuit 5401 to the detection signal V1 output from the positive electrode side detection unit 521 or the detection signal I1 output from the positive electrode side power supply unit 531. At the same time, the switching circuit 5402 switches the detection signal output from the synchronous detection circuit 5401 to the output destination of the detection signal input to the synchronous detection circuit 5401.

  Switching circuit 5402 includes an input switch 5402A and an output switch 5402B. The input switching unit 5402A and the output switching unit 5402B are switched simultaneously by a switching signal output from the switching signal generator 5403.

  In the input switch 5402A, the first input terminal is connected to the output terminal of the operational amplifier OA2 of the positive power supply unit 531 shown in FIG. 4, and the second input terminal is connected to the positive side detection unit 521 shown in FIG. The output terminal of the amplifier circuit 5213 is connected. The output terminal is connected to the input terminal of the synchronous detection circuit 5401.

In the output switch 5402B, the input terminal is connected to the output terminal of the synchronous detection circuit 5401. The first output terminal is connected to the current detection terminal (I1) of the calculation unit 550, the second output terminal is connected to the voltage detection terminal (V1) of the calculation unit 550 together with the input terminal of the positive side subtractor 5411,
The switching signal generator 5403 alternately switches the switching signal output to the switching circuit 5402 between an H (High) level and an L (Low) level at a predetermined cycle.

  For example, the switching signal generator 5403 outputs an H level switching signal to the input switching unit 5402A and the output switching unit 5402B.

  Accordingly, the input switch 5402A connects between the output terminal of the operational amplifier OA2 of the positive power supply unit 531 and the input terminal of the synchronous detection circuit 5401, and the output switch 5402B includes the output terminal of the synchronous detection circuit 5401. And the current detection terminal (I1) of the calculation unit 550 are connected.

  Thus, the bipolar AC signal input from the first input terminal of the input switch 5402A to the unipolar conversion circuit 410 of the synchronous detection circuit 5401 is converted into a unipolar AC signal by the unipolar conversion circuit 410. The converted AC signal is subjected to removal of unnecessary signals by the signal multiplication circuit 420 and the signal extraction filter 430, and is input to the current detection terminal (I1) of the arithmetic unit 550 via the first output terminal of the output switch 5402B. The

  The switching signal generator 5403 outputs an L level switching signal to the input switching unit 5402A and the output switching unit 5402B.

  Accordingly, the input switch 5402A connects between the output terminal of the amplifier circuit 5213 of the positive polarity detection unit 521 and the input terminal of the synchronous detection circuit 5401, and the output switch 5402B outputs the output of the synchronous detection circuit 5401. The terminal and the voltage detection terminal (V1) of the calculation unit 550 are connected.

  As a result, the bipolar AC signal input from the second input terminal of the input switch 5402A to the unipolar converter circuit 410 is converted by the unipolar converter circuit 410 into a unipolar AC signal. Unnecessary signals are removed from the converted AC signal by the signal multiplication circuit 420 and the signal extraction filter 430, and the voltage detection terminal (V1) and the positive side of the arithmetic unit 550 are connected via the second output terminal of the output switch 5402B. Input to the subtractor 542.

  When the switching signal is switched from the L level to the H level in this way, the synchronous detection circuit 5401 is used as a processing circuit that removes noise of the detection signal output from the positive power supply unit 531 by the switching circuit 5402.

  On the other hand, when the switching signal is switched from the H level to the L level, the synchronous detection circuit 5401 is used by the switching circuit 5402 as a processing circuit for removing noise of the detection signal output from the positive electrode side detection unit 521.

  According to the second embodiment of the present invention, the switching means configured by the switching circuit 5402 receives the AC signal I1 output from the positive power supply unit 531 and the AC signal V1 output from the positive detection unit 521. The signals are alternately switched and input to the unipolar conversion circuit 410. The switching unit outputs the unipolar AC signal output from the unipolar conversion circuit 410 to the arithmetic unit 550 via the signal multiplication circuit 420 and the signal extraction filter 430.

  Thus, the synchronous detection circuit 5401 can be used as a circuit for removing unnecessary signals included in the detection signal I1, and can also be used as a circuit for removing unnecessary signals included in the detection signal V1. For this reason, the number of synchronous detection circuits 5401 provided in the impedance measuring apparatus 5 can be reduced.

  Furthermore, by using a single synchronous detection circuit 5401, compared with the case where the synchronous detection circuit is provided separately as in the first embodiment, it is possible to suppress a decrease in measurement accuracy due to the individual difference of each synchronous detection circuit. Can do. Therefore, the accuracy required for the synchronous detection circuit 5401 can be relaxed, and the manufacturing cost of the synchronous detection circuit 5401 can be suppressed.

  Therefore, by using the switching circuit 5402 also as the synchronous detection circuit 5401, the impedance measuring apparatus 5 can be downsized and the manufacturing cost can be reduced while maintaining and improving the accuracy of measuring the internal impedance.

  In this embodiment, the example in which the synchronous detection circuit of the positive power supply unit 531 is also used as the synchronous detection circuit of the positive detection unit 521 has been described. However, the synchronous detection circuit of the negative power supply unit 532 is used as the negative detection unit 522. The synchronous detection circuit may also be used. In this case, the configuration on the negative electrode side of the AC adjustment unit 540 is basically the same as the configuration on the positive electrode side shown in FIG.

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

  In the present embodiment, the AC adjustment unit 540 includes an AC signal source that generates a unipolar AC signal, instead of the AC signal source 546 that generates the bipolar AC signal shown in FIG. The unipolar alternating current signal output from the alternating current signal source 546 is an alternating current signal whose amplitude is centered on a half value of the voltage value in a range from zero to a predetermined voltage value.

  For this reason, the current command signal output from the AC adjustment unit 540 to the positive power supply unit 521 changes around the half value of the voltage value Vo in the range from zero to the voltage value Vo.

For this reason, the current command signal output from the AC adjustment unit 540 to the positive power supply unit 5 3 1 changes around the half value of the voltage value Vo in the range from zero to the voltage value Vo.

  The positive power supply unit 531 includes a detection resistance element Rs and a bipolar conversion circuit 440.

  The detection resistance element Rs is a resistance element for detecting the magnitude of the current command signal proportional to the alternating current I1. One end of the detection resistance element Rs is connected to the positive output terminal of the AC adjustment unit 540 shown in FIG. 5, and the other end of the detection resistance element Rs is connected to the input end of the bipolar conversion circuit 440. The amplitude of the detection voltage generated at both ends of the detection resistance element Rs is proportional to the amplitude of the alternating current I1.

  The bipolar conversion circuit 440 is polarity conversion means for converting the current command signal output from the AC adjustment unit 540 from a unipolar AC voltage to a bipolar AC current I1. The amplitude of the alternating current I1 output from the bipolar conversion circuit 440 is proportional to the amplitude of the current command signal. For example, the amplitude of the alternating current I1 increases as the amplitude of the current command signal increases.

  The bipolar conversion circuit 440 is realized by a transformer in this embodiment. The transformer is composed of a primary coil and a secondary coil.

  One end of the primary coil is connected to the positive output terminal of the AC adjustment unit 540 via the detection resistance element Rs, and the other end of the primary coil is grounded.

  One end of the secondary coil is connected to the capacitor 511A shown in FIG. 3, and the other end of the secondary coil is grounded.

  In the bipolar conversion circuit 440, when a unipolar AC voltage is supplied to the primary coil as a current command signal, a bipolar AC current I1 proportional to the inductance L of the transformer and the magnetic coupling coefficient is applied to the secondary coil. Flowing. For this reason, the alternating current I1 is output from the bipolar conversion circuit 440 to the capacitor 511A.

  FIG. 14 is a diagram illustrating an AC signal converted by the bipolar conversion circuit 440.

  The bipolar conversion circuit 440 converts a unipolar AC signal whose minimum value is zero into a bipolar AC signal that changes between 0 V and positive and negative.

  As described above, in the present embodiment, the AC adjustment unit 540 is provided with the AC signal source 546 for generating a unipolar AC signal, and the bipolar conversion circuit 440 is replaced with the positive polarity side instead of the voltage-current conversion circuit 5311 shown in FIG. Provided in the power supply unit 531.

  Thus, the positive-side power supply unit 531 can be simplified, and the AC signal source 546 is different from the AC signal source 546 shown in FIG. Therefore, the AC signal source itself can be simplified.

  Further, since the primary coil and the secondary coil are insulated, even if noise is propagated from the load 3 to the secondary coil by arranging the detection resistance element Rs on the primary coil side of the transformer, Noise from the load 3 is not propagated to the next coil. Therefore, it is possible to suppress a decrease in detection accuracy of the alternating current I1 due to noise from the load 3. The detection resistance element Rs may be disposed on the secondary coil side of the transformer. In this case, the alternating current I1 actually input to the positive terminal 211 can be detected more accurately.

  In this embodiment, the example in which the bipolar conversion circuit 440 is provided in the positive power supply unit 531 has been described, but the bipolar conversion circuit 440 may be provided in the negative power supply unit 532 instead of the current-voltage conversion circuit. Thereby, the structure of the negative electrode side power supply part 532 can be simplified.

  According to the third embodiment of the present invention, the polarity conversion means including the bipolar conversion circuit 440 is, for example, the AC current I1 input to the DC cutoff means including the positive side DC cutoff unit 511. Is converted from a unipolar AC signal to a bipolar AC signal. Bipolar conversion circuit 440 is composed of a transformer, and converts unipolar AC voltage Vi1 into bipolar AC current I1 by the transformer.

  In this way, the polarity conversion means converts the AC signal that is voltage-current converted (processed) by the power supply means that includes the positive-side power supply unit 531 from unipolar to bipolar. As a result, since the bipolar AC current I1 is output to the DC interrupting unit 511, an AC current having the same waveform as the AC current I1 output from the power supply means is supplied to the positive electrode terminal 211 without saturating the DC interrupting unit 511. Can be output.

  Therefore, by using a transformer as the bipolar conversion circuit 440 for the positive power supply unit 531 and the negative power supply unit 532, while maintaining the measurement accuracy of the impedance measuring device 5, the positive power supply unit 531 and the negative power supply unit 532 The configuration can be simplified.

  Further, by combining the first to third embodiments, the AC signal processed in the impedance measuring device 5 can be unified into a unipolar AC signal. Therefore, the number of components used in the signal multiplication circuit 420, the positive power supply unit 531 and the negative power supply unit 532 can be reduced. Thereby, while being able to simplify the impedance measuring apparatus 5, manufacturing cost can be suppressed.

  As described above, according to the above embodiment, the unipolar conversion circuit 410 and the bipolar conversion circuit 440 are configured such that the DC side of the positive side DC blocking unit 511 and the DC side blocking unit 512 of the negative side are connected as shown in FIG. Connected between the blocking unit and the calculation unit 550. Thereby, since the components used for the impedance measuring apparatus 5 can be reduced, the impedance measuring apparatus 5 can be reduced in size and cost.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  In the above embodiment, the synchronous detection circuit 5214 illustrated in FIG. 4 has been described as 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. The imaginary axis component of the detection signal can be 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.

  In the above embodiment, the calculation unit 550 has described 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 is an imaginary axis of the AC potential differences V1 and V2. The electrostatic capacity of the fuel cell stack 1 may be calculated by obtaining the components.

  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.

  Further, the circuit configuration of the impedance measuring device 5 may be simplified as long as the internal resistance on the positive electrode side and the negative electrode side hardly changes. For example, the AC adjustment unit 540 is omitted, and the AC currents I1 and I2 whose amplitude and phase match are fixedly output from the power supply units 531 and 532. Also, one of the detection units 521 and 522 is omitted, and an AC potential difference (for example, AC potential difference V1) detected only by the other detection unit (for example, the positive electrode side detection unit 521) and an AC current (for example, AC current) that causes the AC potential difference. The internal resistance is calculated using the current I1). Even with such a circuit configuration, the same effect as in the above embodiment can be obtained.

  Further, in the present embodiment, the halfway point terminal 213 is provided in the middle of the fuel cell stack 1, and the AC currents I1 and I2 are set so that the AC adjustment unit 540 sets the AC potential differences V1 and V2 to the same reference value Vs. An example of controlling the amplitude has been described. However, the midpoint terminal 213 may be provided in the power generation cell 10 that is out of the power generation cell 10 located in the middle of the fuel cell stack 1. In this case as well, the AC potential Va generated at the positive terminal 211 and the AC potential Vb generated at the negative terminal need only coincide with each other, so that the internal resistance R1 and the internal resistance R2 depend on the position of the power generation cell 10 provided with the halfway terminal 213. And a reference value Vs of each amplitude of the AC potential differences V1 and V2 may be set in accordance with the resistance ratio.

  In addition, the said embodiment can be combined suitably.

Claims (6)

Power supply means for outputting an alternating current to a positive electrode and a negative electrode of a laminated battery in which a plurality of battery cells are laminated;
Detecting means for detecting an AC potential difference between at least one of the AC potential difference between the positive electrode and the middle point of the laminated battery and the AC potential difference between the negative electrode and the halfway point;
Calculation means for calculating the impedance of the laminated battery based on the AC potential difference detected by the detection means and the AC current output from the power supply means;
Polarity conversion means for converting an AC signal processed by at least one of the power supply means and the detection means between bipolar and unipolar;
An impedance measuring device comprising: The impedance measuring device according to claim 1,
A DC blocking unit that passes an AC signal output from at least one of the positive electrode and the negative electrode to the detection unit;
Based on a reference signal having the same frequency as the AC current, an extraction circuit that extracts a signal component of the same frequency from the AC signal including the AC potential difference output from the detection means,
The polarity conversion means includes a unipolar conversion circuit that is connected between the DC cutoff unit and the extraction circuit and converts an AC signal output from the DC cutoff unit from bipolar to unipolar.
Impedance measuring device. The impedance measuring device according to claim 1 or 2,
Output from the power supply means to at least one of the positive electrode and the negative electrode so that the AC potential difference between the positive electrode and the midpoint and the AC potential difference between the negative electrode and the midpoint match. Adjusting means for adjusting the alternating current generated,
Current detection means for detecting an alternating current output from the power supply means;
Based on a reference signal having the same frequency as the alternating current, an extraction circuit for extracting a signal component of the same frequency from the alternating current signal output from the current detection means,
The polarity conversion means includes a unipolar conversion circuit that is connected between the current detection means and the extraction circuit and converts a bipolar AC signal output from the current detection means into a unipolar AC signal.
Impedance measuring device. The impedance measuring device according to claim 2,
Current detection means for detecting an alternating current output from the power supply means;
The AC signal output from the detection means and the AC signal output from the current detection means are alternately switched and input to the unipolar conversion circuit, and the unipolar AC signal output from the unipolar conversion circuit Switching means for outputting to the arithmetic means via the extraction circuit,
Impedance measuring device. The impedance measuring device according to any one of claims 2 to 4,
The extraction circuit includes:
An operational amplifier having a non-inverting input terminal to which the unipolar AC signal is input, and an inverting input terminal to which the same unipolar AC signal is input as the non-inverting input terminal,
A transistor for connecting or blocking between the non-inverting input terminal and the ground terminal based on a reference signal having the same frequency as the alternating current,
The operational amplifier rectifies the unipolar AC signal by the transistor.
Impedance measuring device. The impedance measuring device according to any one of claims 1 to 5, wherein
A DC blocking unit that passes an AC signal output from the power supply means to at least one of the positive electrode and the negative electrode;
The polarity conversion means includes a bipolar conversion circuit that converts an AC signal input to the DC blocking unit from monopolar to bipolar.
The bipolar conversion circuit includes a transformer, and outputs a bipolar AC current to the DC cutoff unit by the transformer.
Impedance measuring device.

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