WO2017061036A1

WO2017061036A1 - Impedance measurement device and processing method therefor

Info

Publication number: WO2017061036A1
Application number: PCT/JP2015/078780
Authority: WO
Inventors: 隆宏藤井; 酒井　政信; 青木　哲也
Original assignee: 日産自動車株式会社
Priority date: 2015-10-09
Filing date: 2015-10-09
Publication date: 2017-04-13

Abstract

An impedance measurement device including a switch for switching between a measurement state in which an object of measurement is connected to a power supply circuit and a diagnosis state in which a passive element is connected to the power supply circuit outputs AC current to the object of measurement. The impedance measurement device extracts the resistance component of the AC potential difference generated in the object of measurement on the basis of an AC signal having the same frequency as the AC current, extracts the reactance component on the basis of an AC signal having a phase orthogonal to that of the AC signal, and calculates the resistance component or reactance component of the impedance of the object of measurement on the basis of the extracted components and the AC current. When extracting the reactance component when the switch has been switched to the diagnosis state, the impedance measurement device shifts the phase of the AC signal from among the AC current and the orthogonal AC signals that corresponds to the passive element. The impedance measurement device diagnoses impedance error or corrects impedance on the basis of each component extracted when the switch was switched to the diagnosis state.

Description

Impedance measuring apparatus and processing method thereof

The present invention relates to an impedance measuring apparatus including a passive element for specifying an impedance measurement error of a measurement object and a processing method thereof.

In WO2012 / 077450A1, the internal resistance of a laminated battery is detected by outputting an alternating current to the laminated battery to be measured in a state in which power is supplied from the laminated battery to the load, and detecting the alternating potential difference generated in the laminated battery. Measuring devices for measuring have been proposed.

In the measurement apparatus described above, an electronic component such as an operational amplifier is used for a circuit that outputs an alternating current, a circuit that detects an alternating potential difference, or the like. For this reason, the accuracy of measuring the impedance of the laminated battery is reduced due to manufacturing variations of electronic parts, deterioration with time, output fluctuation accompanying temperature rise, and the like. Therefore, it is possible to provide a passive element in the measurement device, measure the impedance of the passive element, and specify a measurement error that occurs in the measurement device.

For example, in a measuring device that measures not only the resistance component of the fuel cell but also the capacitance component in order to detect the state of hydrogen in the fuel cell, the measurement error of the resistance component and the capacitance component is specified as described above. As a passive element, not only a resistor but also a capacitor is required. Since the capacitor has a large volume, there is a problem that if the measuring device is provided with two passive elements, the measuring device becomes large.

The present invention has been made paying attention to such problems, and an impedance measuring apparatus and a processing method thereof capable of suppressing an increase in scale while suppressing a decrease in measurement accuracy due to an electronic component. The purpose is to provide.

According to an aspect of the present invention, an impedance measuring device is configured to calculate an impedance of the measurement target based on a power supply circuit that outputs an alternating current to the measurement target, an AC potential difference generated in the measurement target, and an output current of the power supply circuit. An arithmetic unit for calculation, a passive element of any one of a resistor, a capacitor, and a coil for specifying the impedance error, a measurement state in which the measurement target is connected to the power supply circuit, and the passive element And a switch for switching a diagnosis state connected to the power supply circuit. The processing method of the impedance measuring apparatus includes an output step of outputting an alternating current to the measurement target by the power supply circuit, and a detection step of detecting an AC potential difference generated in the measurement target. This processing method includes a first oscillation step for outputting an AC signal having the same frequency as the output current of the power supply circuit, and an AC detected in the detection step based on the output signal in the first oscillation step. A first extraction step of extracting a resistance component of the potential difference. The processing method includes: a second oscillation step for outputting an AC signal whose phase is orthogonal to the output signal at the first oscillation step; and the detection step based on the output signal at the second oscillation step. A second extraction step of extracting a reactance component of the AC potential difference detected in step (b). Furthermore, this processing method is an arithmetic operation for calculating a resistance component or reactance component of the impedance of the measurement object based on the component extracted in the first or second extraction step and the alternating current output in the output step. Includes steps. Further, in the processing method, when the reactance component is extracted in the second extraction step when the switch is switched to the diagnosis state, the processing method is compared with the case where the resistance component is extracted in the first extraction step. An output step, and a phase shifting step of shifting the phase of the output signal corresponding to the passive element among the output signals in the first oscillation step and the second oscillation step. In this processing method, when the switch is switched to the diagnosis state, an error in the impedance calculated in the calculation step is diagnosed based on each component extracted in the first and second extraction steps. The processing step which performs a process or the process which correct | amends the said impedance is included.

FIG. 1 is a configuration diagram showing an example of the configuration of the impedance measuring apparatus according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing measurement results of resistance components and reactance components when the phase of a power supply circuit that outputs an alternating current to one diagnostic element is operated by 90 degrees. FIG. 3 is an explanatory diagram showing the relationship between the type of diagnostic element and the oscillation circuit that is the target of the phase operation. FIG. 4 is a circuit diagram illustrating a configuration of a circuit that extracts a resistance component and a reactance component of an AC potential difference generated in a measurement target. FIG. 5 is a flowchart illustrating an example of a processing procedure regarding the phase control method of the impedance measuring apparatus according to the present embodiment. FIG. 6 is a time chart showing an example of a phase operation method for operating the phase of the alternating current during the diagnosis period of the impedance measuring device. FIG. 7 is a diagram showing a basic configuration of an impedance measuring apparatus according to the second embodiment of the present invention. FIG. 8 is a circuit diagram illustrating a configuration of a blocking unit that blocks direct current and a detection unit that detects a potential difference. FIG. 9 is a circuit diagram showing a configuration of a power supply unit that outputs an alternating current to the positive electrode and the negative electrode of the laminated battery to be measured. FIG. 10 is a configuration diagram illustrating a configuration of an AC adjustment unit that adjusts the amplitude of the AC current output to the positive electrode and the negative electrode of the laminated battery. FIG. 11 is a configuration diagram illustrating a configuration of an AC detection circuit provided in the AC adjustment unit. FIG. 12 is a circuit diagram illustrating a configuration of a circuit that extracts a resistance component and a reactance component of an AC potential difference generated in the stacked battery. FIG. 13 is a configuration diagram illustrating a configuration of a calculation unit that calculates the resistance component and reactance component of the impedance of the stacked battery. FIG. 14 is a flowchart showing an example of an equipotential control method for controlling the AC potentials generated at the positive electrode and the negative electrode of the laminated battery equally. FIG. 15 is a time chart showing the state of the impedance measuring apparatus when equipotential control is executed. FIG. 16 is an explanatory diagram showing an AC potential generated at the positive electrode and the negative electrode of the laminated battery by equipotential control. FIG. 17 is a configuration diagram illustrating a detailed configuration of the impedance measuring apparatus according to the present embodiment. FIG. 18 is a connection diagram illustrating a connection state in the impedance measuring apparatus when a measurement error is specified using a diagnostic element. FIG. 19 is a diagram illustrating an example of a correction method for correcting a measurement result using a diagnostic element. FIG. 20 is a flowchart illustrating an example of a processing procedure regarding the phase control method of the impedance measuring apparatus according to the present embodiment.

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

(First embodiment)
FIG. 1 is a configuration diagram showing an example of the configuration of the impedance measuring apparatus according to the first embodiment of the present invention.

The measurement object 10 is an object having a resistance (electric resistance) R component and a reactance X component. The measurement object 10 of the present embodiment is equivalent to an electric circuit in which a capacitor constituting the reactance X and a resistor having a resistance R are connected in parallel to each other. Examples of the measurement object 10 include a secondary battery and a fuel cell.

The impedance measuring device 5a is a device that measures the resistance component and reactance component of the impedance of the measurement object 10. The impedance measuring device 5a has a self-diagnosis function in order to suppress impedance measurement errors caused by fluctuations in the output of electronic components provided in the impedance measuring device 5a itself.

The impedance measuring device 5a includes a detection circuit 20, an R component extraction circuit 21, an X component extraction circuit 22, a power supply circuit 30, oscillation circuits 40a to 40c, a quadrature phase shifter 41, and an arithmetic unit 50. . Furthermore, the impedance measuring device 5a includes a diagnostic element 60, a diagnostic element information holding unit 61, a switch 70, and a diagnostic control unit 80.

The oscillation circuits 40a to 40c are circuits that oscillate an AC signal having a reference frequency fb that is a predetermined frequency. The oscillation circuits 40a to 40c are circuits that can change the phase of the AC signal.

The oscillation circuit 40 a outputs an AC signal having a reference frequency to the power supply circuit 30. The oscillation circuit 40 b outputs an AC signal having the reference frequency fb to the R component extraction circuit 21. The oscillation circuit 40 c outputs an AC signal having a reference frequency to the quadrature phase shifter 41.

The quadrature phase shifter 41 advances the phase of the output signal, which is an AC signal output from the oscillation circuit 40c, by 90 degrees. The quadrature phase shifter 41 outputs an AC signal obtained by advancing the phase of the output signal of the oscillation circuit 40c by 90 degrees to the X component extraction circuit 22. The oscillation circuit 40c and the quadrature phase shifter 41 constitute an orthogonal signal oscillation circuit that outputs an AC signal whose phase is orthogonal to the output signal of the oscillation circuit 40b.

The power supply circuit 30 is a circuit that outputs an alternating current having a reference frequency fb at one end of the measurement object 10 based on the alternating current signal output from the oscillation circuit 40a. The power supply circuit 30 is realized by a plurality of operational amplifiers, for example.

The detection circuit 20 is a circuit that detects an AC potential difference (voltage) generated in the measurement object 10 to which an AC current is applied by the power supply circuit 30. The detection circuit 20 is realized by, for example, a differential amplifier or an instrumentation amplifier. The detection circuit 20 outputs an AC potential difference signal V indicating a value obtained by detecting the AC potential difference to the R component extraction circuit 21 and the X component extraction circuit 22, respectively.

The R component extraction circuit 21 extracts a real part component of the AC potential difference signal V, that is, a resistance component, based on the AC signal output from the oscillation circuit 40b. Note that the oscillation circuit 40 b constitutes a reference signal oscillation circuit that outputs an AC signal having the same frequency with respect to the output current of the power supply circuit 30.

In the present embodiment, the R component extraction circuit 21 extracts the resistance component Vr of the AC potential difference signal based on the AC signal having the same phase with respect to the output current of the power supply circuit 30. The configuration of the R component extraction circuit 21 will be described with reference to the following diagram. The R component extraction circuit 21 outputs the extracted resistance component Vr of the AC potential difference signal to the calculator 50.

The X component extraction circuit 22 extracts the imaginary part component of the AC potential difference signal V, that is, the reactance component, based on the AC signal output from the quadrature phase shifter 41.

In this embodiment, the X component extraction circuit 22 extracts the reactance component Vx of the AC potential difference signal based on the AC signal whose phase is advanced by 90 degrees with respect to the output current of the power supply circuit 30. The configuration of the X component extraction circuit 22 will be described with reference to the next figure. The X component extraction circuit 22 outputs the reactance component Vx of the extracted AC potential difference signal to the calculator 50.

The computing unit 50 computes the resistance component R and reactance component X of the impedance of the measurement object 10 based on the alternating current I output from the power supply circuit 30 and the resistance component Vr and reactance component Vx of the AC potential difference signal. To do.

Specifically, the arithmetic unit 50 calculates the impedance resistance component R by dividing the resistance component Vr of the AC potential difference signal by the amplitude of the AC current I. Further, the computing unit 50 divides the reactance component Vx of the AC potential difference signal by the amplitude of the AC current I to calculate the reactance component X of the impedance.

The computing unit 50 outputs the calculated resistance component R and reactance component X as measurement results to, for example, a management device that manages the state of the measurement object 10.

As described above, the detection circuit 20 and the power supply circuit 30 use electronic components such as operational amplifiers, that is, analog circuits. For this reason, it is caused by manufacturing variations of electronic components, deterioration with time in which the performance of the electronic components decreases with time, temperature drift in which the output of the electronic components fluctuates as the temperature of the electronic components rises, etc. The error included in the measurement result increases. As a result, the measurement accuracy of the impedance measuring device 5a is lowered. As a countermeasure, the impedance measuring device 5a includes a diagnostic element 60, a diagnostic element information holding unit 61, a switch 70, and a diagnostic control unit 80.

The diagnostic element 60 is a passive element of any one of a resistor, a capacitor, and an inductor for specifying an impedance measurement error calculated by the calculator 50. One end of the diagnostic element 60 is grounded, and the other end is connected to the second output terminal of the switch 70. In the present embodiment, the diagnostic element 60 is configured by a resistor having a resistance having a reference value.

The diagnostic element information holding unit 61 holds diagnostic element information indicating the resistance value of the diagnostic element 60 (hereinafter referred to as “reference value”).

The switch 70 is provided between the connection terminal 10p of the measurement object 10 and the power supply circuit 30. The input terminal of the switch 70 is connected to the detection circuit 20 and the power supply circuit 30, and the first output terminal of the switch 70 is connected to the connection terminal 10p.

The switch 70 has a measurement state in which the measurement object 10 is connected to the power supply circuit 30 and a diagnosis state in which the diagnosis element 60 is disconnected from the measurement object 10 and the diagnosis element 60 is connected to the power supply circuit 30. Switch. The connection state of the switch 70 is controlled by the diagnosis control unit 80.

The diagnosis control unit 80 switches the connection state of the switch 70 to the measurement state or the diagnosis state based on a predetermined diagnosis condition.

For example, the diagnosis control unit 80 includes a timer for measuring time, and monitors whether or not the measurement time of the timer has passed a predetermined measurement period as a diagnosis condition, and every time the measurement time passes the measurement period, The connection state of the switch 70 is switched from the measurement state to the diagnosis state. When a specific diagnosis period has elapsed after switching to the diagnosis state, the diagnosis control unit 80 returns the connection state of the switch 70 from the diagnosis state to the measurement state, and resets the timer.

Alternatively, the diagnosis control unit 80 monitors whether or not the internal temperature of the impedance measuring device 5a is higher than a predetermined threshold as a diagnostic condition, and determines the connection state of the switch 70 when the internal temperature rises above the threshold. You may make it switch from a measurement state to a diagnosis state.

When the connection state of the switch 70 is switched to the diagnosis state, the diagnosis control unit 80 uses the diagnosis element 60 to generate a diagnosis execution signal for specifying the measurement error of the impedance resistance component R and reactance component X. Output to 50.

The diagnosis control unit 80 outputs the diagnosis execution signal to the computing unit 50 and then shifts the phase of the AC signal output from the oscillation circuit 40a by 90 degrees in order to identify the measurement error of the reactance component X. When the reactance component X is calculated by the computing unit 50 using the diagnostic element 60, the diagnostic control unit 80 restores the phase of the AC signal output from the oscillation circuit 40a.

When the calculator 50 receives the diagnosis execution signal from the diagnosis controller 80, the calculator 50 uses the diagnosis element 60 to execute a diagnosis process for calculating a measurement error due to the electronic component of the impedance measuring device 5a.

In the diagnosis process, the computing unit 50 acquires the resistance component Vr of the AC potential difference signal generated in the diagnostic element 60 from the R component extraction circuit 21, and based on the acquired resistance component Vr and the output current I of the power supply circuit 30, The resistance value R _d of the diagnostic element 60 is calculated. The computing unit 50 calculates the difference between the calculated resistance value _Rd and the reference value held in the diagnostic element information holding unit 61 as a measurement error of the impedance resistance component.

When the diagnosis control unit 80 shifts the phase of the output signal of the oscillation circuit 40a by 90 degrees in the delay direction, the X component extraction circuit 22 converts the resistance component Vr of the AC potential difference generated in the diagnostic element 60 into the AC potential difference. Is extracted as the reactance component Vx. The computing unit 50 acquires the reactance component Vx of the extracted AC potential difference, and calculates the reactance value X _d of the diagnostic element 60 based on the acquired reactance component Vx and the output current I of the power supply circuit 30. The computing unit 50 calculates the difference between the calculated reactance value _Xd and the reference value of the diagnostic element information holding unit 61 as a measurement error of the inductance component.

The computing unit 50 outputs each measurement error of the impedance resistance component and the reactance component to the diagnostic element information holding unit 61. The diagnosis control unit 80 returns the phase of the output signal of the oscillation circuit 40a to the original state and outputs a measurement execution signal instead of the diagnosis execution signal when the switch 70 is switched to the measurement state.

When the arithmetic unit 50 receives the measurement execution signal from the diagnosis control unit 80, the arithmetic unit 50 executes a correction process for correcting the measurement result based on the measurement error recorded in the diagnostic element information holding unit 61.

In this embodiment, the computing unit 50 acquires the resistance component Vr and reactance component Vx of the AC potential difference generated in the measurement object 10 from the R component extraction circuit 21 and the X component extraction circuit 22. As described above, the computing unit 50 determines the impedance resistance component R and reactance component of the measurement object 10 based on the acquired resistance component Vr and reactance component Vx of the AC potential difference and the amplitude of the output current I of the power supply circuit 30. X is calculated as a measurement result.

In the correction process, the arithmetic unit 50 adds the measurement error of the resistance component R held in the diagnostic element information holding unit 61 to the resistance component R of the measurement result, and converts the measurement error of the reactance component X into the measurement result. Add to reactance component X.

In the present embodiment, the object 10 to be measured has a capacitor (electric capacity) component, but the object 10 to be measured may have an inductance (electric induction) component as a reactance X component.

FIG. 2 is a diagram illustrating a measurement result of the diagnostic element 60 when the phase of the alternating current I output from the power supply circuit 30 is switched from 0 degrees to 90 degrees in the diagnosis state. FIG. 2 shows the measurement results when the resistance value of the diagnostic element 60 is changed stepwise.

In FIG. 2, the horizontal axis indicates the resistance component R of impedance, and the vertical axis indicates the reactance component X of impedance. The impedance resistance component X increases as the output signal Vr of the R component extraction circuit 21 increases, and the impedance reactance component X increases as the output signal Vx of the X component extraction circuit 22 increases.

As shown in FIG. 2, when the phase θ of the alternating current I of the power supply circuit 30 is set to 0 degrees, the diagnostic element 60 is a resistance element, so the reactance component X is zero, and only the magnitude of the resistance component R is Change.

On the other hand, when the phase θ of the output current I of the power supply circuit 30 is switched from 0 degree to minus 90 degrees, the resistance component R becomes zero and only the magnitude of the reactance component X changes. This principle will be briefly described below.

In general, when an alternating current I is applied from the power supply circuit 30 to the resistor R, the phase of the alternating potential difference Vr generated in the resistor R becomes the same as the phase of the alternating current I. On the other hand, when the alternating current I is applied from the power supply circuit 30 to the capacitor C, the phase of the alternating potential difference Vc generated in the capacitor C is delayed by 90 degrees (π / 2) with respect to the phase of the alternating current I. When the alternating current I is applied from the power supply circuit 30 to the coil L, the phase of the alternating potential difference V _L generated in the coil L advances by 90 degrees (π / 2) with respect to the phase of the alternating current I.

Therefore, in the X component extraction circuit 22, in order to detect the capacitance component C of the reactance X, the signal component whose phase is shifted by 90 degrees in the delay direction with respect to the AC current I in the AC potential difference signal V from the detection circuit 20. Only is extracted. Therefore, in order to apply the alternating current I from the power supply circuit 30 to the diagnostic element 60 having the resistance R and extract the alternating potential difference Vr output from the diagnostic element 60 by the X component extraction circuit 22, the phase of the alternating current I Can be delayed by 90 degrees.

Therefore, as shown in FIG. 2, the AC potential difference generated in the diagnostic element 60 is changed in the X component extraction circuit 22 by reacting the reactance component of the diagnostic element 60 by delaying the phase of the alternating current I output from the power supply circuit 30 by 90 degrees. Output as Vx. For this reason, it is possible to specify the measurement error due to the electronic component in the signal path from the power supply circuit 30 to the X component extraction circuit 22, that is, the measurement error of the reactance component X, using the diagnostic element 60 that is a resistor. Become.

Thus, by shifting the phase θ of the alternating current I of the power supply circuit 30 by minus 90 degrees, not only the measurement error of the resistance component R but also the measurement error of the reactance component X is measured using one diagnostic element 60. can do. According to this embodiment, in order to measure the measurement error of the resistance component R and the reactance component X, it is only necessary to provide the impedance measuring device 5a with one resistor. Since the resistor used as the diagnostic element 60 has a smaller volume than the capacitor, the measurement accuracy of both the resistance component and the reactance component of the impedance of the measurement object 10 is suppressed while suppressing an increase in the circuit scale of the impedance measuring device 5a. Can be improved.

In the present embodiment, the phase of the alternating current I is shifted by 90 degrees in the delay direction, but the phase of the alternating current I may be shifted by 90 degrees in the advance direction. In such a case, since the output signal of the X component extraction circuit 22 only has a negative value and the absolute value does not change, the absolute value of the output signal of the X component extraction circuit 22 and the reference value of the diagnostic element 60 Can be compared.

In the present embodiment, the phase of the alternating current I output from the power supply circuit 30 is manipulated. However, when a resistor is used as the diagnostic element 60, the alternating current supplied from the oscillation circuit 40b to the X component extraction circuit 22 is used. The phase of the signal may be manipulated.

FIG. 3 is an explanatory diagram showing an example of the relationship between the type of passive element used as the diagnostic element 60 and an oscillation circuit that can be a target of phase operation among the oscillation circuits 40a to 40c.

FIG. 3 shows an operation method 1 for manipulating the phase of the output current I of the power supply circuit 30 and an operation method 2 for manipulating the phase of the output signal of one of the oscillation circuits 40b and 40c. Yes.

In the operation method 1, when a resistor is mounted as the diagnostic element 60, the phase of the output current I of the power supply circuit 30 is shifted by, for example, 90 degrees when the measurement error of the reactance component X is specified using the resistor. Let When a coil is mounted as the diagnostic element 60, when the measurement error of the resistance component R is specified using the coil, the phase of the output current I of the power supply circuit 30 is shifted by, for example, 90 degrees in the delay direction. When a capacitor is mounted as the diagnostic element 60, when the measurement error of the resistance component R is specified using the capacitor, the phase of the output current I of the power supply circuit 30 is shifted, for example, by 90 degrees in the advance direction.

In the operation method 2, when a resistor is mounted as the diagnostic element 60, the phase of the output signal of the oscillation circuit 40c is shifted by, for example, 90 degrees when the measurement error of the reactance component X is specified using the resistor. . When a coil is mounted as the diagnostic element 60, when the measurement error of the resistance component R is specified using the coil, the phase of the output signal of the oscillation circuit 40b is shifted by 90 degrees in the delay direction, for example. When a capacitor is mounted as the diagnostic element 60, when the measurement error of the resistance component R is specified using the capacitor, the phase of the output signal of the oscillation circuit 40b is shifted, for example, by 90 degrees in the advance direction.

In this way, by manipulating the phase of the output signal of at least one of the oscillation circuits 40a to 40c in accordance with the passive element used for the diagnostic element 60, the resistance component R and the reactance component can be obtained by one passive element. The measurement error of both X can be measured. Therefore, it is possible to suppress an increase in the circuit scale of the impedance measuring device 5a.

Further, since the volume of the capacitor or coil is larger than that of the resistor, it is possible to further suppress the increase in circuit scale by using the resistor as the diagnostic element 60. In addition, although the example which performs one operation of the phase operation 1 and the phase operation 2 was demonstrated in FIG. 3, you may perform the phase operation 1 and the phase operation 2 simultaneously. For example, when a resistor is used as the diagnostic element 60, when the measurement error of the reactance component is specified using the resistor, the phase of the output signal of the oscillation circuit 40a is shifted 45 degrees in the delay direction, and the output of the oscillation circuit 40c is output. The phase of the signal is shifted 45 degrees in the advance direction. Even with such an operation, it is possible to measure the measurement error of the reactance component.

FIG. 4 is a configuration diagram showing an example of the configuration of the R component extraction circuit 21 and the X component extraction circuit 22.

The R component extraction circuit 21 multiplies the AC potential difference signal V from the detection circuit 20 by the in-phase signal Sin (0) for detecting the resistance component R of the measurement object 10, thereby realizing a real part component of the AC potential difference signal. The resistance component Vr is extracted. The in-phase signal Sin (0) is an AC signal having the same phase as the output current I of the power supply circuit 30. The R component extraction circuit 21 includes an in-phase multiplier 21a and an in-phase low-pass filter (LPF) 21b.

The in-phase multiplier 21a calculates the AC signal from the oscillation circuit 40b as the in-phase signal Sin (0) to the multiplied AC potential difference signal V. Thereby, an in-phase AC signal corresponding to the degree of coincidence between the waveform of the AC potential difference signal V and the waveform of the in-phase signal Sin (0) is output from the in-phase multiplier 21a. For example, when the AC potential difference signal V and the in-phase signal Sin (0) are completely in phase, an in-phase AC signal having a full-wave rectified waveform is output. Further, as the degree of coincidence between the waveforms of the AC potential difference signal V and the in-phase signal Sin (0) increases, the resistance component Vr of the AC potential difference increases.

The in-phase low-pass filter 21b detects the DC component of the in-phase AC signal. The in-phase low-pass filter 21b removes the AC component or the high-frequency region component of the in-phase AC signal and passes the DC component of the in-phase AC signal. The DC component smoothed by the in-phase low-pass filter 21b is input to the calculator 50 as the resistance component Vr of the AC potential difference detection signal.

In this way, the R component extraction circuit 21 multiplies the AC potential difference V by the in-phase signal Sin (0) having the same phase as the output current I of the power supply circuit 30, whereby the in-phase signal Sin (0 Only the resistance component Vr having the same phase as that of FIG. For this reason, even if the resistance component Vr is buried in the noise in the AC potential difference signal V, the R component extraction circuit 21 can detect the resistance component Vr with high accuracy.

The R component extraction circuit 21 outputs the real part component of the AC potential difference signal V to the calculator 50. The calculator 50 calculates the resistance component R of the measurement object 10 based on the real part component of the AC potential difference signal V and the output current I of the power supply circuit 30. Thus, since the resistance component R is obtained from the real part component of the AC potential difference signal V, in this embodiment, the real part component of the AC potential difference signal V is referred to as a resistance component Vr.

The X component extraction circuit 22 multiplies the AC potential difference signal V by the quadrature signal Sin (90) for detecting the reactance component X of the measurement object 10, thereby obtaining a reactance component Vx that is an imaginary part component of the AC potential difference signal. Extract. The quadrature signal Sin (90) is an AC signal having a phase angle orthogonal to the output current I of the power supply circuit 30 and having the same amplitude as the in-phase signal Sin (0). The X component extraction circuit 22 includes an orthogonal multiplier 22a and an orthogonal low-pass filter 22b.

The quadrature multiplier 22a multiplies the AC potential difference V by the AC signal from the quadrature phase shifter 41 as the orthogonal signal Sin (90). Thereby, an orthogonal AC signal corresponding to the degree of coincidence between the waveform of the AC potential difference V1 and the waveform of the orthogonal signal is output from the orthogonal multiplier 22a.

The orthogonal low-pass filter 22b detects the DC component of the orthogonal AC signal. The orthogonal low-pass filter 22b removes the AC component or the high-frequency region component of the orthogonal AC signal and passes the DC component of the orthogonal AC signal. The direct current component smoothed by the orthogonal low-pass filter 22b is input to the computing unit 50 as the reactance component Vx of the alternating current potential difference signal.

Thus, the X component extraction circuit 22 extracts only the reactance component Vx having the same phase as that of the orthogonal signal Sin (90) from the AC potential difference signal V by multiplying the AC potential difference V by the orthogonal signal Sin (90). For this reason, even if the reactance component Vx is buried in the noise in the AC potential difference signal, the reactance component Vx can be reliably detected by the X component extraction circuit 22 with high accuracy.

The X component extraction circuit 22 outputs the imaginary part component of the AC potential difference signal V to the calculator 50. The computing unit 50 computes the reactance component X of the measurement object 10 based on the imaginary part component of the AC potential difference signal V and the output current I of the power supply circuit 30. Thus, since the reactance component R is obtained from the imaginary part component of the AC potential difference signal V, in this embodiment, the imaginary part component of the AC potential difference signal V is referred to as a reactance component Vr.

FIG. 4 is a flowchart showing an example of a processing method of the impedance measuring apparatus 5a in the present embodiment. This processing method is repeatedly executed at a predetermined cycle (for example, several ms).

First, in step S1, the diagnosis control unit 80 determines whether or not it is time for the impedance measurement device 5a to diagnose its own measurement state. When the diagnosis control unit 80 determines that the diagnosis time has come, it supplies a diagnosis execution signal to the computing unit 50.

In step S2, the diagnosis control unit 80 controls the switch 70 to connect the diagnosis element 60 to the detection circuit 20 and the power supply circuit 30 when the diagnosis time comes. As a result, the alternating current I is applied from the power supply circuit 30 to the diagnostic element 60, and the alternating potential difference V generated in the diagnostic element 60 is detected by the detection circuit 20.

In step S3, when the arithmetic unit 50 receives the diagnosis execution signal, it obtains the resistance component Vr of the AC potential difference signal from the R component extraction circuit 21, and measures the resistance component R of the impedance based on the resistance component Vr of the AC potential difference signal. Calculate the error.

Specifically, the arithmetic unit 50 calculates the resistance value of the diagnostic element 60 based on the resistance component Vr of the AC potential difference signal and the AC current I of the power supply circuit 30, and the calculated value and the diagnostic element information holding unit 61. A difference from the reference value is calculated as a measurement error of the resistance component R.

In step S4, when the measurement error of the resistance component R is calculated, the diagnosis control unit 80 shifts the phase of the output current I of the power supply circuit 30 from 0 degrees to 90 degrees in the delay direction. That is, the diagnosis control unit 80 shifts the phase of the AC signal output from the oscillation circuit 40a by 90 degrees from 0 degrees in the delay direction. As a result, the phase of the AC potential difference signal output from the detection circuit 20 is delayed by 90 degrees, so that the X component extraction circuit 22 can extract the AC potential difference generated in the diagnostic element 60.

In step S5, when the phase of the alternating current I is shifted by 90 degrees, the computing unit 50 acquires the reactance component Vx of the alternating potential difference signal from the X component extraction circuit 22, and measures the reactance component X of the impedance based on the reactance component Vr. Calculate the error.

Specifically, the computing unit 50 calculates a reactance value corresponding to the resistance value of the diagnostic element 60 based on the reactance component Vx of the AC potential difference signal and the AC current I of the power supply circuit 30. The computing unit 50 calculates the difference between the calculated reactance value and the reference value of the diagnostic element information holding unit 61 as a measurement error of the reactance component X.

In step S6, when the measurement error of the reactance component X is calculated, the diagnosis control unit 80 returns the phase of the output current I of the power supply circuit 30 to 0 degrees. That is, the diagnosis control unit 80 shifts the phase of the AC signal output from the oscillation circuit 40a by 90 degrees in the advance direction.

Next, when it is determined in step S1 that it is not the diagnosis time, the process proceeds to step S7.

In step S7, the diagnosis control unit 80 controls the switch 70 to connect the measurement object 10 to the detection circuit 20 and the power supply circuit 30 when it is not the diagnosis time. As a result, the alternating current I is applied from the power supply circuit 30 to the measurement object 10, and the alternating potential difference V generated in the diagnostic element 60 is detected by the detection circuit 20. Then, the diagnosis control unit 80 transmits a measurement execution signal to the computing unit 50 instead of the diagnosis execution signal.

In step S8, when receiving the measurement execution signal, the arithmetic unit 50 acquires the resistance component Vr and the reactance component Vx from the R component extraction circuit 21 and the X component extraction circuit 22, and based on these components, the measurement object 10 is obtained. Resistance component R and reactance component X are calculated.

Specifically, the computing unit 50 calculates the resistance component R of the measurement object 10 based on the resistance component Vr and the AC current I of the AC potential difference signal, and generates the reactance component Vx and the AC current I of the AC potential difference signal. Based on this, the reactance component X of the measurement object 10 is calculated.

In step S9, the computing unit 50 corrects the calculated resistance component R and reactance component X based on the measurement errors calculated in steps S3 and S5, respectively. For example, the computing unit 50 adds the measurement error calculated in step S3 to the resistance component R, and adds the measurement error calculated in step S5 to the reactance component X. The computing unit 50 outputs the corrected resistance component R and reactance component X as measurement results to a controller that manages the measurement object 10.

In step 10, the computing unit 50 repeats a series of processing procedures from step S1 to S9 until the impedance measuring device 5a is stopped (OFF), and ends the processing method when the impedance measuring device 5a is stopped. .

FIG. 5 is a time chart showing an example of a diagnostic technique for specifying measurement errors of both the resistance component R and the reactance component using one diagnostic element 60.

FIG. 5A is a diagram illustrating a connection state of the switch 70. FIG. 5B is a diagram illustrating a change in the phase of the alternating current I output from the power supply circuit 30. FIG. 5C is a diagram showing a change in the output signal Vr of the R component extraction circuit 21. FIG. 5D is a diagram showing changes in the output signal Vx of the X component extraction circuit 22. The horizontal axis of each drawing from FIG. 5A to FIG. 5D is a common time axis. Here, it is assumed that there are almost no measurement errors of the resistance component R and the reactance component X caused by the electronic components.

Prior to time t1, as shown in FIG. 5A, the connection state of the switch 70 is a measurement state in which the measurement object 10 is connected to the power supply circuit 30. Therefore, as shown in FIGS. 5C and 5D, the resistance component Vr and the reactance component Vx of the AC potential difference generated in the measurement object 10 are respectively output.

At time t1, the diagnosis time comes, and as shown in FIG. 5A, the diagnosis control unit 80 switches the switch 70 to a diagnosis state in which the diagnosis element 60 is connected to the detection circuit 20 and the power supply circuit 30. As a result, an alternating current I is applied from the power supply circuit 30 to the diagnostic element 60, and an alternating potential difference signal V indicating an alternating potential difference generated in the diagnostic element 60 is input to the R component extraction circuit 21 and the X component extraction circuit 22.

At this time, since the diagnostic element 60 is a resistor, the phase of the AC potential difference signal V matches the phase of the AC current I. Therefore, since the amplitude component of the AC potential difference signal V is extracted by the R component extraction circuit 21, as shown in FIG. 5C, the output signal Vr of the R component extraction circuit 21 is a reference when the measurement error is zero. The level is almost the same as the voltage. The calculator 50 calculates the resistance value of the diagnostic element 60 based on the output signal Vr of the R component extraction circuit 21 and the alternating current I, and calculates the difference between the resistance value and the reference value as an error of the resistance component R at the time of measurement. Calculate as On the other hand, as shown in FIG. 5D, the output signal Vx of the X component extraction circuit 22 becomes substantially zero.

At time t2, as shown in FIG. 5B, the phase of the alternating current I is delayed by 90 degrees by the diagnosis control unit 80. As a result, the phase of the AC potential difference signal V is also delayed by 90 degrees, and therefore coincides with the phase of the output signal of the quadrature phase shifter 41 supplied to the X component extraction circuit 22. The amplitude component can be extracted.

Therefore, as shown in FIG. 5 (d), the output signal Vx of the X component extraction circuit 22 is at the same level as the reference voltage. The calculator 50 calculates a reactance value based on the output signal Vx of the X component extraction circuit 22 and the alternating current I, and calculates a difference between the reactance value and the reference value as an error of the reactance component X at the time of measurement. . On the other hand, as shown in FIG. 5C, the output signal Vr of the R component extraction circuit 21 becomes substantially zero.

At time t3, the phase of the alternating current I is returned to 0 degrees as shown in FIG. 5 (b), and the switch 70 is switched to the measurement state as shown in FIG. 5 (a). Then, the computing unit 50 calculates the resistance component R and the reactance component X of the measurement object 10 as measurement results.

Thus, by delaying the phase of the alternating current I by 90 degrees during the diagnosis period, the X component extraction circuit 22 can extract the resistance component of the diagnosis element 60 as a reactance component. For this reason, even if a resistor is used as the diagnostic element 60, it is possible to measure a measurement error due to an output fluctuation of an electronic component in a signal path for measuring a reactance component in the impedance measuring device 5a.

In the present embodiment, the phase of the alternating current I output from the power supply circuit 30 is shifted by 90 degrees, but the amount of phase operation is not limited to 90 degrees.

For example, the phase of the output current I of the power supply circuit 30 may be shifted by 45 degrees. In this case, signals of substantially the same level are output from both the R component extraction circuit 21 and the X component extraction circuit 22. Theoretically, both signals output a value obtained by multiplying the reference voltage by Sin (45 °). For this reason, since the measurement error of the resistance component R and the reactance component X can be calculated simultaneously, the diagnosis period can be shortened.

Further, instead of manipulating the phase of the output current I of the power supply circuit 30, the phase of the quadrature signal Sin (90) input to the X component extraction circuit 22, that is, the phase of the output signal of the oscillation circuit 40c is manipulated by 90 degrees. May be. Even in this case, since the signal corresponding to the reference voltage is output from both the R component extraction circuit 21 and the X component extraction circuit 22, the diagnosis period is shortened while suppressing a decrease in accuracy of measuring the measurement error. It becomes possible.

According to the first embodiment of the present invention, the impedance measuring device 5 a includes the power supply circuit 30 that outputs an alternating current to the measurement object 10 and the detection circuit 20 that detects the alternating potential difference V generated in the measurement object 10. . The impedance measuring device 5a also includes a first oscillation circuit 40b that outputs an AC signal Sin (0) having the same frequency as the output current I of the power supply circuit 30, and an output signal Sin (0) of the first oscillation circuit 40b. And a first extraction circuit 21 for extracting the resistance component Vr of the AC potential difference detected by the detection circuit 20. Furthermore, the impedance measuring device 5a includes a quadrature phase shifter 41 constituting a second oscillation circuit that outputs an AC signal Sin (90) whose phase is orthogonal to the output signal Sin (0) of the first oscillation circuit 40b, And a second extraction circuit 22 that extracts the reactance component Vx of the AC potential difference detected by the detection circuit 20 based on the output signal Sin (90) of the quadrature phase shifter 41.

The impedance measuring device 5a includes the measurement object 10 based on the component Vr or Vx extracted by the first extraction circuit 21 or the second extraction circuit 22 and the alternating current I output by the power supply circuit 30. An arithmetic unit 50 for calculating the resistance component R or reactance component X of the impedance is provided. Further, the impedance measuring device 5 a connects the passive object 60 of any one of a resistor, a capacitor, and a coil for specifying an error in the impedance calculated by the calculator 50 and the measurement object 10 to the power supply circuit 30. A switch 70 that switches between a measurement state and a diagnosis state in which the passive element 60 is connected to the power supply circuit 30 and a diagnosis control unit 80 that controls the connection state of the switch 70 are provided.

In the case where the switch 70 is switched to the diagnosis state, the diagnosis control unit 80 extracts the reactance component X by the second extraction circuit 22 as compared with the case where the first extraction circuit 21 extracts the resistance component R. Of the circuit 30, the first oscillation circuit 40b, and the second oscillation circuit 40c, the phase of the output signal of the circuit corresponding to the passive element 60 is shifted. Then, the 50 computing unit diagnoses an error in the impedance of the measurement object 10 based on the components Vr and Vx extracted by the first extraction circuit 21 and the second extraction circuit 22 using the passive element 60, or Correct the impedance.

As described above, the phase of the output signal of at least one of the power supply circuit 30, the first oscillation circuit 40b, and the second oscillation circuit 40c is controlled in accordance with the type of the passive element 60 as shown in FIG. Thus, it is possible to specify measurement errors of both the resistance component R and the reactance component X with only one diagnostic element. Therefore, it is possible to suppress a decrease in impedance measurement accuracy while suppressing an increase in circuit scale and manufacturing cost of the impedance measuring device 5a.

Further, according to the present embodiment, the diagnostic element 60 is a resistor having a reference value of resistance, and the diagnostic control unit 80 extracts the reactance component X by the second extraction circuit 22 using the resistor. In this case, the phase of at least one AC signal among the output signals of the power supply circuit 30 and the quadrature phase shifter 41 is shifted by a predetermined angle.

Thus, by using a resistor as the diagnostic element 60, it is possible to further reduce the size of the impedance measuring device 5a compared to the case of using a capacitor.

Further, according to the present embodiment, the diagnosis control unit 80 uses the resistor as the diagnosis element 60 to extract the reactance component X by the X component extraction circuit 22, and the alternating current I output from the power supply circuit 30. Is shifted by 45 degrees or 90 degrees.

In this way, by shifting the phase of the output current I of the power supply circuit 30 by 45 degrees, the AC potential difference signal V generated in the diagnostic element 60 can be extracted by both the R component extraction circuit 21 and the X component extraction circuit 22. Thus, the diagnosis period can be shortened. Further, by shifting the phase of the output current I of the power supply circuit 30 by 90 degrees, the S / N ratio (Signal to Noise) becomes the highest, so that the measurement accuracy of the measurement error can be increased.

In addition, according to the present embodiment, the diagnosis control unit 80 uses a resistor as the diagnosis element 60 to extract the reactance component by the X component extraction circuit 22, and the AC signal output from the quadrature phase shifter 41. The phase angle is rotated 90 degrees. Thereby, the measurement error of the resistance component R and the reactance component X can be measured simultaneously, and a decrease in the measurement accuracy can be suppressed. That is, the measurement accuracy can be improved while shortening the diagnosis period.

(Second Embodiment)
FIG. 7 is a configuration diagram showing a basic configuration of the impedance measuring device 5b in the second embodiment of the present invention.

The fuel cell stack 1 is a measurement object of the impedance measurement device 5b in the present embodiment. The fuel cell stack 1 is a stacked battery in which a plurality of power generation cells are stacked, and is mounted on a vehicle, for example. The fuel cell stack 1 is connected to the load 3 and supplies power to the load 3.

The load 3 is, for example, an electric motor or an auxiliary machine of the fuel cell stack 1. The auxiliary equipment of the fuel cell stack 1 is, for example, a compressor that supplies a cathode gas to the fuel cell stack 1 or a heater that heats the cooling water flowing through the fuel cell stack 1 when the fuel cell stack 1 is warmed up.

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

The control unit 6 controls the flow rates of the cathode gas and the anode gas supplied to the fuel cell stack 1 according to the required power required from the load 3, for example. Further, in the fuel cell stack 1, when the electrolyte membrane 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 so that the electrolyte membrane does not become dry or excessively wet. Adjust the cathode gas flow rate.

The control unit 6 is provided with an operation switch unit 6a for starting the fuel cell system, a temperature sensor 6b for detecting the ambient temperature of the fuel cell stack 1, and the like.

The impedance measuring device 5b measures the internal impedance of the fuel cell stack 1. In the present embodiment, the impedance measuring device 5 b measures the resistance component R and reactance capacitance component C of the fuel cell stack 1, and transmits the measured values of the resistance component R and capacitance component C to the control unit 6. When the control unit 6 receives the measured value of the resistance component R of the fuel cell stack 1 from the impedance measuring device 5b, the control unit 6 controls the wet state of the fuel cell stack 1 based on the measured value of the resistance component R. Further, when the control unit 6 receives the measurement value of the capacity component C of the fuel cell stack 1 from the impedance measurement device 5b, the anode gas supplied to the fuel cell stack 1 is insufficient based on the measurement value of the capacity component R. It is determined whether or not it is in a state.

The impedance measuring device 5b 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. Furthermore, the impedance measuring device 5b includes a diagnosis control unit 580 corresponding to the diagnosis control unit 80 shown in FIG.

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 is connected to the positive terminal 211 of the fuel cell stack 1. The negative electrode side DC blocking unit 512 is connected to the negative electrode terminal 212 of the fuel cell stack 1. The midpoint DC blocking unit 513 is connected to the midpoint terminal 213 of the fuel cell stack 1. The midpoint terminal 213 is connected to a power generation cell located in the middle of the plurality of power generation cells stacked from the positive electrode terminal 211 to the negative electrode terminal 212. The midpoint terminal 213 may be connected to a power generation cell at a position off the midpoint between the positive terminal 211 and the negative terminal 212.

DC blocking units 511 to 513 block a DC signal and allow an AC signal to flow. The DC blockers 511 to 513 are realized by, for example, capacitors or transformers. Note that the midpoint DC blocking unit 513 indicated by a broken line can be omitted.

The positive electrode side detection unit 521 detects a potential difference between the AC potential Va generated at the positive electrode terminal 211 and the AC potential Vc generated at the midway terminal 213 (hereinafter referred to as “AC potential difference V1”). The positive electrode side detection unit 521 outputs a detection signal whose value changes according to the vibration of the AC potential difference V1 to the calculation unit 550. For example, the value of the detection signal increases as the AC potential difference V1 increases, and the value of the detection signal decreases as the AC potential difference V1 decreases. In the positive electrode side detection unit 521, the first input terminal is connected to the positive electrode terminal 211 via the positive electrode side DC cutoff unit 511, and the second input terminal is connected to the midpoint terminal 213 via the midpoint DC cutoff unit 513. .

The negative electrode side detection unit 522 detects a potential difference (hereinafter referred to as “AC potential difference V2”) between the AC potential Vb generated at the negative electrode terminal 212 and the AC potential Vc generated at the midway terminal 213. The negative electrode side detection unit 522 outputs a detection signal indicating the AC potential difference V2 to the calculation unit 550. In the negative electrode side detection unit 522, the first input terminal is connected to the negative electrode terminal 212 via the negative electrode side DC blocking unit 512, and the second input terminal is connected to the midpoint terminal 213 via the midpoint DC blocking unit 513. . The positive electrode side detection unit 521 and the negative electrode side detection unit 522 are realized by, for example, a differential amplifier (instrumentation amplifier).

Details of the positive power supply unit 531 and the negative power supply unit 532 will be described with reference to FIG.

The positive power supply unit 531 is a power supply circuit that outputs an alternating current having a reference frequency fb. The positive power supply unit 531 is realized by a voltage-current conversion circuit such as an operational amplifier (OP amplifier). This voltage-current converter circuit outputs a current Io proportional to the input voltage Vi. Note that Io = Vi / Rs, where Rs is a current sensing resistance. This voltage-current conversion circuit is used as a variable AC current source capable of adjusting the output current Io according to the input voltage Vi.

By using a voltage-current conversion circuit as the positive-side power supply unit 531, the output current Io can be obtained by the input voltage Vi ÷ proportional constant Rs without actually measuring the output current Io. The current Io can be obtained. The negative power supply unit 532 has the same configuration. That is, the negative power supply unit 532 is a power supply circuit that outputs an alternating current having a reference frequency fb.

Details of the AC adjustment unit 540 will be described with reference to FIG.

The AC adjustment unit 540 determines the amplitude of the AC current output 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. Adjust.

In the present embodiment, the AC adjustment unit 540 determines the amplitude of the AC current output from the positive power supply unit 531 and the negative power supply so that the amplitude levels of the positive AC potential difference V1 and the negative AC potential difference V2 are equal. Both the amplitude of the alternating current output from the unit 532 is increased or decreased. The AC adjustment unit 540 is realized by, for example, a PI (Proportional Integral) control circuit.

In addition, the AC adjustment unit 540 sends the current command signals for the positive power supply unit 531 and the negative power supply unit 532 to the calculation unit 550 as AC currents I1 and I2 output from the positive power supply unit 531 and the negative power supply unit 532. Output.

The AC adjustment unit 540 includes a positive-side detection circuit 5411, a positive-side subtractor 5421, a positive-side integration circuit 5431, a positive-side multiplier 5441, a negative-side detection circuit 5412, a negative-side subtractor 5422, and a negative-side An integration circuit 5432 and a negative side multiplier 5442 are included.

Furthermore, the AC adjustment unit 540 includes a reference power source 545 and an AC signal source 546a. The reference power source 545 outputs a reference potential (hereinafter referred to as “reference voltage Vs”) set in order to match the positive-side AC potential difference V1 and the negative-side AC potential difference V2. The reference voltage Vs is a value determined by experiments or the like.

The AC signal source 546a is an oscillation source that oscillates an AC signal having the reference frequency fb, and corresponds to the oscillation circuit 40a shown in FIG. The AC signal source 546a is a circuit capable of changing the phase of the AC signal, and the phase of the AC signal output from the AC signal source 546a is controlled by the diagnosis control unit 580.

The reference frequency fb is set to a predetermined frequency suitable for measuring the internal impedance of the fuel cell stack 1. For example, when the wet state of the electrolyte membrane of the fuel cell stack 1 is detected, the reference frequency fb is set to 1 kHz (kilohertz), for example, in order to measure the resistance component R correlated with the wet state of the electrolyte membrane. The In addition, when detecting a hydrogen shortage state in the fuel cell stack 1, the reference frequency fb is set to a frequency lower than 1 kHz, for example, in order to measure the capacitance component C correlated with the hydrogen shortage state. The

When the positive-side detection circuit 5411 receives the detection signal indicating the AC potential difference V1 output from the positive-side detection unit 521, the positive-side detection circuit 5411 removes unnecessary signals included in the detection signal and makes the detection signal proportional to the amplitude of the AC potential difference V1. Convert to DC signal. For example, the positive detector circuit 5411 outputs the average value or effective value of the detection signal as a DC signal proportional to the amplitude of the AC potential difference V1.

In the present embodiment, the positive detection circuit 5411 is realized by a synchronous detection circuit. The positive-side detection circuit 5411 extracts a real part component that is a resistance component of the AC potential difference V1 and an imaginary part component that is a capacitance component of the AC potential difference V1, and a vector of the AC potential difference V1 based on the real part component and the imaginary part component. A vector value V1p indicating the magnitude of is calculated. The positive detection circuit 5411 outputs the vector value V1p to the positive subtractor 5421 as a DC signal proportional to the amplitude of the AC potential difference V1.

When the average value or effective value of the detection signals is used, if the phase difference between the AC potential difference V1 and the AC potential difference V2 increases, even if the amplitudes of the AC potential differences V1 and V2 are the same, the actual AC potential difference V1 or V2 is not detected. Since the partial component is small, the amplitude of the alternating current I1 or I2 may be excessively increased or decreased. On the other hand, by using the vector value V1p, the amplitude component of the AC potential difference V1 or V2 can be accurately obtained, so that the amplitudes of the AC currents I1 and I2 can be accurately adjusted. The detailed configuration of the positive detection circuit 5411 will be described later with reference to the next drawing.

The positive side subtractor 5421 calculates a difference signal indicating a deviation width of the vector value Vp1 from the reference voltage Vs by subtracting the reference voltage Vs from the vector value Vp1 of the AC potential difference V1 detected by the positive side detection circuit 5411. . For example, the signal level of the differential signal increases as the deviation width from the reference voltage Vs increases.

The positive side integration circuit 5431 integrates the difference signal output from the positive side subtracter 5421 to average or adjust the sensitivity of the difference signal. Then, the positive side integration circuit 5431 outputs the integrated difference signal to the positive side multiplier 5441.

The positive-side multiplier 5441 multiplies the AC signal of the reference frequency fb output from the AC signal source 546a by the difference signal, thereby generating the AC voltage signal so that the amplitude of the AC potential difference V1 converges to the reference voltage Vs. Generate. As the signal level of the differential signal increases, the amplitude of the AC voltage signal increases.

The positive-side multiplier 5441 outputs the generated AC voltage signal as a current command signal to the positive-side power supply unit 531 shown in FIG. The AC voltage signal Vi input to the positive power supply unit 531 is converted into an AC current signal Io by the positive power supply unit 531 and output to the positive terminal 211 of the fuel cell stack 1.

Thus, based on the AC signal output from the AC signal source 546a, the AC current I1 output from the positive power supply unit 531 is generated. That is, by shifting the phase of the AC signal output from the AC signal source 546a, the phase of the AC current I1 output from the positive power supply unit 531 is similarly shifted.

Note that the negative-polarity detection circuit 5412, the negative-polarity subtractor 5422, the negative-polarity integration circuit 5432, and the negative-polarity multiplier 5442 are respectively a positive-polarity detection circuit 5411, a positive-polarity subtracter 5421, a positive-polarity integration circuit 5431, and a positive-polarity multiplication. The configuration is similar to that of the instrument 5441.

Thus, the AC adjustment unit 540 adjusts the amplitude of the AC current I1 output from the positive power source 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.

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 5b 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, details of the positive-side detector circuit 5411 will be described with reference to FIG.

The positive polarity detection circuit 5411 includes an R component extraction circuit 21, an X component extraction circuit 22, a vector calculation unit 23, a quadrature phase shifter 41, and

AC signal sources

546b and 546c. Note that the R component extraction circuit 21, the X component extraction circuit 22, and the quadrature phase shifter 41 are the same as those shown in FIG.

AC signal sources

546b and 546c correspond to the oscillation circuits 40b and 40c shown in FIG. 1, respectively. The

AC signal sources

546b and 546c are both oscillation sources that oscillate an AC signal having the reference frequency fb. In the present embodiment, the phases of the AC signals output from the

AC signal sources

546b and 546c coincide with the phases of the AC signals output from the AC signal source 546a shown in FIG.

The

AC signal sources

546b and 546c are circuits that can change the phase of the AC signal, and the phase of the AC signal output from the

AC signal sources

546b and 546c can be controlled by the diagnosis control unit 580. Further, the output signals of the

AC signal sources

546b and 546c may be shifted in phase from the output signal of the AC signal source 546a in consideration of a capacitance component parasitic in the impedance measuring device 5.

The R component extraction circuit 21 extracts the real part component of the AC potential difference V1 based on the AC signal from the AC signal source 546. The R component extraction circuit 21 outputs the extracted real axis component to the calculation unit 550 and the vector calculation unit 23 as the resistance component V1r of the AC potential difference V1.

The X component extraction circuit 22 extracts the imaginary part component of the AC potential difference V1 based on the AC signal from the quadrature phase shifter 41, that is, the AC signal whose phase is orthogonal to the AC signal from the AC signal source 546. The X component extraction circuit 22 outputs the extracted imaginary part component to the calculation unit 550 and the vector calculation unit 23 as the reactance component V1x of the AC potential difference V1.

The vector calculation unit 23 calculates the vector value V1p of the AC potential difference based on the real part component V1r and the imaginary part component V1x. Specifically, the vector calculation unit 230 calculates the square value of the sum of the square value of the real part component V1r and the square value of the imaginary part component V1x as shown in the following equation (1) to obtain the vector value V1p.

The vector calculation unit 23 outputs the calculated AC potential difference vector value V1p to the positive-side subtractor 5421.

Thus, the positive electrode side detection circuit 5411 detects the resistance component V1r and the reactance component V1x of the AC potential difference, respectively. Then, the positive electrode side detection circuit 5411 reproduces the vector value V1p of the AC potential difference and outputs it to the positive electrode side subtracter 5421. Note that the negative electrode side detection circuit 5412 has the same configuration as the positive electrode side detection circuit 5411.

Next, details of the R component extraction circuit 21 and the X component extraction circuit 22 will be described with reference to FIG.

The in-phase multiplier 21a includes resistance elements Ra to Rc, an operational amplifier 31, and a switch 32. The resistance element Ra and the resistance element Rb are provided to adjust the magnitude of the current supplied from the positive electrode side detection unit 521. The resistance element Rc is provided to adjust the amplification factor of the operational amplifier 31.

Both one end of the resistance element Ra and one end of the resistance element Rb are connected to the output terminal of the positive electrode side detection unit 521. The other end of the resistor element Ra is connected to the inverting input terminal (−) of the operational amplifier 31 and one end of the resistor element Rc. The other end of the resistance element Rc is connected to the output terminal of the operational amplifier 31. The other end of the resistance element Rb is connected to the non-inverting input terminal (+) of the operational amplifier 31 and one contact terminal of the switch 32. The other contact terminal of the switch 32 is grounded.

To the control terminal of the switch 32, an AC signal from the AC signal source 546b or a pulse signal (rectangular wave) synchronized with the AC signal is input. The switch 32 switches the non-inverting input terminal (+) of the operational amplifier 31 to the ground or non-ground state according to the AC signal having the reference frequency fb.

For example, when the AC signal supplied to the control terminal of the switch 32 is larger than zero, the switch 32 is connected (ON), and the non-inverting input terminal (+) of the operational amplifier 31 is grounded. In this state, since the operational amplifier 31 functions as an inverting amplifier that multiplies the input signal by “−1”, an inverted voltage signal in which the sign of the AC potential difference V1 is inverted is output from the operational amplifier 31.

On the other hand, when the AC signal supplied to the control terminal of the switch 32 is smaller than zero, the switch 32 is cut off (OFF), and the non-inverting input terminal (+) of the operational amplifier 31 is not grounded. In this state, since the operational amplifier 31 functions as a non-inverting amplifier that multiplies the input signal by “+1”, a non-inverting voltage signal in which the sign of the AC potential difference V1 is not inverted is output from the operational amplifier 31. The quadrature multiplier 22a has the same configuration as the in-phase multiplier 21a.

In this way, by switching the non-inverting input terminal (+) of the operational amplifier 31 to the grounded or non-grounded state according to the alternating current signal of the reference frequency fb, the alternating current potential signal V1 is full-wave rectified by the operational amplifier 31 to be in phase. It is output to the low-pass filter 21b. The common-mode low-pass filter 21b includes resistance elements R11 to R13 and capacitance elements C11 to C13. One end of the resistor element R11 is connected to the output terminal of the in-phase multiplier 21a, and the other end of the resistor element R11 is connected to one end of the capacitor element C11. The other end of the capacitive element C11 is grounded. In this way, three RC circuits are connected in series to the in-phase low-pass filter 21b. The in-phase AC signal is rectified by the in-phase low-pass filter 21b and output as a resistance component V1r of the AC potential difference. The quadrature low-pass filter 22b has the same configuration as the in-phase low-pass filter 21b.

Next, details of the calculation unit 550 will be described with reference to FIG.

The computing unit 550 corresponds to the computing unit 50 shown in FIG. The computing unit 550 acquires the positive-side AC potential difference resistance component V1r and reactance component V1x from the positive-side detection circuit 5411, and acquires the negative-side AC potential difference resistance component V2r and reactance component V2x from the negative-side detection circuit 5412. . In addition, the calculation unit 550 acquires current command signals for the positive power supply unit 531 and the negative power supply unit 532 as alternating currents I1 and I2.

And the calculating part 550 calculates the resistance component R1 of the positive electrode side which the fuel cell stack 1 has based on the amplitude of the alternating current I1 of the positive electrode side and the resistance component V1r of the AC potential difference. At the same time, the calculation unit 550 calculates the reactance component C1 on the positive electrode side of the fuel cell stack 1 based on the amplitude of the alternating current I1 on the positive electrode side and the reactance component V1x of the AC potential difference.

Further, the calculation unit 550 calculates the resistance component R2 on the negative electrode side of the fuel cell stack 1 based on the amplitude of the negative current AC current I2 and the resistance component V2r of the AC potential difference. At the same time, the calculation unit 550 calculates the reactance component C2 on the negative electrode side of the fuel cell stack 1 based on the amplitude of the negative-current AC current I2 and the reactance component V2x of the AC potential difference.

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

The AD converter 551 converts the current command signals (I1, I2) and the AC potential difference signals (V1, V2), which are analog signals, into digital numerical signals and transfers them to the microcomputer chip 552.

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

Similarly, the reactance component Xn and the reactance component X of the entire fuel cell stack 1 are calculated by the following equations.

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

The control unit 6 receives the resistance component R and the reactance component X output from the calculation unit 550 as the measurement result of the impedance measuring device 5b. The control unit 6 controls the operating state of the fuel cell stack 1 according to the measurement result.

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

FIG. 14 is a flowchart illustrating an example of a control method when equipotential control performed by the AC adjustment unit 540 is realized by a controller.

In step S101, the controller determines whether or not the positive AC potential Va is greater than a predetermined value. If the determination result is negative, the controller proceeds to step S102, and if the determination result is positive, the controller proceeds to step S103.

In step S102, the controller determines whether or not the positive AC potential Va is smaller than a predetermined value. If the determination result is negative, the controller proceeds to step S104, and if the determination result is positive, the controller proceeds to step S105.

In step S103, the controller reduces the output of the positive power supply unit 531. That is, the controller decreases the amplitude of the alternating current I1. As a result, the positive AC potential Va decreases.

In step S104, the controller maintains the output of the positive power supply unit 531. As a result, the positive AC potential Va is maintained.

In step S105, the controller increases the output of the positive power supply unit 531. As a result, the positive AC potential Va increases.

In step S106, the controller determines whether or not the negative AC potential Vb is greater than a predetermined value. If the determination result is negative, the controller proceeds to step S107, and if the determination result is positive, the controller proceeds to step S108.

In step S107, the controller determines whether or not the negative AC potential Vb is smaller than a predetermined value. If the determination result is negative, the controller proceeds to step S109, and if the determination result is positive, the controller proceeds to step S110.

In step S108, the controller reduces the output of the negative power supply unit 532. As a result, the negative AC potential Vb decreases.

In step S109, the controller maintains the output of the negative power supply unit 532. As a result, the negative AC potential Vb is maintained.

In step S110, the controller increases the output of the negative power supply unit 532. This increases the negative AC potential Vb.

In step S111, the controller determines whether or not the AC potential Va and the AC potential Vb are predetermined values. If the determination result is positive, the controller proceeds to step S112. If the determination result is negative, the controller exits the process.

In step S112, the controller calculates the resistance component R based on the above equations (2-1) and (2-2), and reactance based on the above equations (3-1) and (3-2). The component X is calculated.

FIG. 14 is a time chart when the controller executes equipotential control performed by the AC adjustment unit 540. Note that step numbers are also shown so that the correspondence with the flowchart is easy to understand.

In the initial stage of FIG. 14, the resistance value R1 on the positive electrode side is higher than the resistance value R2 on the negative electrode side (FIG. 14A). In such a state, the controller starts control.

At time t0, neither the positive AC potential Va nor the negative AC potential Vb has reached the control level (FIG. 14C). In this state, the controller repeats steps S101 → S102 → S105 → S106 → S107 → S110 → S111. As a result, the alternating current I1 on the positive electrode side and the alternating current I2 on the negative electrode side increase (FIG. 14B).

When the positive AC potential Va reaches the control level at time t1 (FIG. 14C), the controller repeats steps S101 → S102 → S104 → S106 → S107 → S110 → S111. As a result, the alternating current I1 on the positive electrode side is maintained, and the alternating current I2 on the negative electrode side increases (FIG. 14B).

When the negative AC potential Vb reaches the control level and becomes the same level as the positive AC potential Va at time t2 (FIG. 14C), the controller proceeds from step S101 → S102 → S104 → S106 → S107 → S109 → S111 → S112 is processed. As a result, the positive side alternating current I1 and the negative side alternating current I2 are maintained. Based on the equation (1-1), the resistance value R1 on the positive electrode side and the resistance value R2 on the negative electrode side are calculated. The resistance value R1 on the positive electrode side and the resistance value R2 on the negative electrode side are added together to obtain the entire resistance component R.

After time t3, the resistance value R2 on the negative electrode side increases due to a change in the wet state of the fuel cell stack 1 (FIG. 14A). In this case, the controller repeats steps S101 → S102 → S104 → S106 → S108 → S111 → S112. By processing in this way, the negative-side AC current I2 decreases as the negative-side resistance value R2 increases, so the negative-side AC potential Vb is maintained at the same level as the positive-side AC potential Va. Therefore, the resistance component R is calculated even in this state.

After time t4, the resistance value R2 on the negative electrode side coincides with the resistance value R1 on the positive electrode side (FIG. 14A). In this case, the controller repeats steps S101 → S102 → S104 → S106 → S107 → S109 → S111 → S112. By processing in this way, the positive side AC potential Va and the negative side AC potential Vb are maintained at the same level (FIG. 14C), and the resistance component R is calculated.

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

FIG. 16 is a diagram illustrating the state of the positive electrode potential generated at the positive electrode terminal 211 and the negative electrode potential generated at the negative electrode terminal 212 of the fuel cell stack 1.

During output of the fuel cell stack 1, a DC voltage Vdc output to the load 3 is generated between the positive terminal 211 and the negative terminal 212. Before the impedance measuring device 5b is activated (ON), the positive electrode potential and the negative electrode potential are constant, and the DC voltage Vdc is supplied to the load 3. Thereafter, when the impedance measuring device 5b 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.

Then, according to the current command signal from the AC adjustment unit 540, the positive power supply unit 531 and the negative power supply unit 532 output AC currents I1 and I2 whose amplitudes are adjusted so that the AC potential differences V1 and V2 coincide with each other.

The alternating current I1 output from the positive electrode side power supply unit 531 is supplied to the positive electrode terminal 211 of the fuel cell stack 1 via 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 in the resistance component R1 by supplying the AC current I1 to the resistance component 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, since the alternating current I2 is applied to the resistance component R2 between the negative electrode terminal 212 and the midpoint terminal 213, an AC potential difference V2 (= Vb−Vc) is generated due to a voltage drop in the resistance component R2. The AC potential difference V2 is detected by the negative electrode side detection unit 522.

The AC adjustment unit 540 determines the difference (V1−V2) between the AC potential difference V1 on the positive electrode side of the fuel cell stack 1 and the AC potential difference V2 on the negative electrode side, that is, the difference between the AC potential Va and the AC potential Vb (Va− The positive power supply unit 531 and the negative power supply unit 532 are adjusted so that Vb) is always small. 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.

The calculation unit 550 includes AC potential differences V1 and V2 output from the positive electrode side detection unit 521 and the negative electrode side detection unit 522, and 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 using. Thereby, the resistance component R1 on the positive electrode side and the resistance component R2 on the negative electrode side of the fuel cell stack 1, and the reactance component C1 on the positive electrode side and the reactance component C2 on the negative electrode side of the fuel cell stack 1 are calculated.

Here, since the alternating current potentials of the positive electrode terminal 211 and the negative electrode terminal 212 have the same value, even if the load 3 is connected to the traveling motor or the like with respect to the positive electrode terminal 211 and the negative electrode terminal 212, the alternating current I1 or I2 can be prevented from leaking to the load 3. For this reason, the resistance components R1 and R2 and the reactance components C1 and C2 of the fuel cell stack 1 can be accurately measured by the alternating currents I1 and I2 output from the positive power supply unit 531 and the negative power supply unit 532.

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

However, the positive electrode side power supply unit 531 and the negative electrode side power supply unit 532, the positive electrode side detection unit 521, the negative electrode side detection unit 522, the AC adjustment unit 540, and the like of the impedance measuring device 5b are configured by electronic components such as operational amplifiers, that is, analog circuits. Has been. Such electronic components are subject to manufacturing variations, deterioration over time in which performance deteriorates with time, temperature drift in which output values fluctuate as temperature rises, and the like. In connection with this, the precision which measures the impedance which the impedance measuring apparatus 5b has will fall. As a countermeasure, in the present embodiment, in addition to the configuration of the impedance measuring device 5b described above, a diagnostic element for specifying a measurement error is provided.

FIG. 17 is a configuration diagram showing a detailed configuration of the impedance measuring device 5b in the present embodiment. Here, the same components as those shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

In FIG. 17, the signal line 501 includes an input line 501 </ b> A in which an alternating current I <b> 1 is input from the positive power supply unit 531 to the positive terminal 211 of the fuel cell stack 1, and an alternating potential Va from the positive terminal 211 to the positive detection unit 521. And an output line 501B to be output. Similarly, in the signal line 502, the AC potential Vb is output from the negative power supply unit 532 to the input line 502 </ b> A where the alternating current I <b> 2 is input to the negative electrode terminal 212 of the fuel cell stack 1, and from the negative electrode terminal 212 to the negative electrode detection unit 522. Output line 502B.

In this manner, by separating each of the

signal lines

501 and 502 into two lines, only the AC potential signal output from the positive terminal 211 and the negative terminal 212 is detected by the positive side detection unit 521 and the negative side detection unit 522. It becomes possible to do. For this reason, the measurement accuracy of the impedance measuring device 5b can be improved.

Further, a capacitor 511A is connected to the input line 501A as the DC blocking unit 511 shown in FIG. 7, and a capacitor 511B is connected to the output line 501B as the DC blocking unit 511. Similarly, a capacitor 512A is connected to the input line 502A as the DC cutoff unit 512, and a capacitor 512B is connected to the output line 502B as the DC cutoff unit 512.

The impedance measuring device 5b includes

diagnostic elements

561 and 562, a switching unit 570, and a diagnostic control unit 580 in addition to the basic configuration shown in FIG. The impedance measuring device 5b includes

bandpass filters

5211 and 5221.

The

diagnostic elements

561 and 562 correspond to the diagnostic element 60 shown in FIG. 1, and are any one of a resistor, a capacitor, and a coil for specifying a measurement error caused by an electronic component of the impedance measuring device 5b. It is a passive element. In the present embodiment, the

diagnostic elements

561 and 562 are resistors having electrical resistance.

Diagnostic element 561 has a resistance of reference value Ref1. Diagnostic element 562 has a resistance of reference value Ref2. In the present embodiment, the reference value Ref1 of the diagnostic element 561 and the reference value Ref2 of the diagnostic element 562 are the same value.

The diagnostic element 561 is disposed at a position where it can be connected in parallel to the positive electrode side detection unit 521. The diagnostic element 562 is disposed at a position where it can be connected in parallel to the negative electrode side detection unit 522. The reference values Ref1 and Ref2 are set to values within a range where the resistance components R1 and R2 of the fuel cell stack 1 vary. As the

diagnostic elements

561 and 562, for example, resistors having 50 mΩ (milliohm) are used.

The switching unit 570 corresponds to the switch 70 shown in FIG. The switching unit 570 is configured to measure the signal path of the AC signal in the impedance measuring device 5b, the measurement state (battery connection state) for measuring the impedance of the fuel cell stack 1, or the resistance of the

diagnostic elements

561 and 562. Switch to the diagnosis state (element connection state). The connection state of the switching unit 570 is controlled by the diagnosis control unit 580.

In the measurement state, the switching unit 570 connects the positive-side power source unit 531 to the positive-electrode terminal 211, and the resistance component R1 and the capacitance component C1 between the positive-electrode terminal 211 and the halfway-point terminal 213 in the fuel cell stack 1 The detection units 521 are connected in parallel. The switching unit 570 connects the negative power source unit 532 to the negative electrode terminal 212, and detects the negative component on the resistance component R2 and the capacitive component C2 between the negative electrode terminal 212 and the halfway terminal 213 in the fuel cell stack 1. 522 are connected in parallel.

On the other hand, in the diagnosis state, the switching unit 570 disconnects the positive power source unit 531 from the positive terminal 211 of the fuel cell stack 1 and connects it to the diagnostic element 561, and the diagnostic element 561 is connected in parallel to the positive electrode detection unit 521. Connect to. The switching unit 570 disconnects the negative power supply unit 532 from the negative terminal 212 and connects it to the diagnostic element 562, and connects the diagnostic element 562 to the negative detection unit 522 in parallel.

The switching unit 570 includes current

path switching devices

571 and 572 and detection

target switching devices

573 and 574. The current

path switching devices

571 and 572 and the detection

target switching devices

573 and 574 are realized by analog switches or relays, for example.

The current path switch 571 is connected between the positive power supply unit 531 and the capacitor 511A. Then, the current path switch 571 switches the supply destination of the alternating current I1 output from the positive power supply unit 531 to the positive terminal 211 or the diagnostic element 561 of the fuel cell stack 1. In the current path switch 571, the input terminal is connected to the positive power supply unit 531, the first output terminal is connected to the capacitor 511A, and the second output terminal is connected to the diagnostic element 561.

The current path switch 572 is connected between the negative power supply unit 532 and the capacitor 512A. The current path switch 572 switches the supply destination of the alternating current I2 output from the negative power supply unit 532 to the negative terminal 212 or the diagnostic element 562 of the fuel cell stack 1. In the current path switch 572, the input terminal is connected to the negative power supply unit 532, the first output terminal is connected to the capacitor 512A, and the second output terminal is connected to the diagnostic element 562.

The detection target switch 573 is connected between the band pass filter 5211 and the positive electrode side detection unit 521. The detection target switching unit 573 selects a detection target connected in parallel to the positive electrode side detection unit 521 as a positive electrode side portion from the positive electrode terminal 211 to the midway terminal 213 of the fuel cell stack 1 or a diagnostic element 561. Switch to. In the detection target switch 573, the first input terminal is connected to the band pass filter 5211, the second input terminal is connected to the diagnostic element 561, and the output terminal is connected to the positive electrode side detection unit 521.

The detection target switch 574 is connected between the band pass filter 5221 and the negative electrode side detection unit 522. The detection target switching unit 574 switches the detection target connected in parallel to the negative electrode side detection unit 522 to the negative electrode side portion from the negative electrode terminal 212 to the halfway terminal 213 of the fuel cell stack 1 or the diagnostic element 562. . In the detection target switch 574, the first input terminal is connected to the band pass filter 5221, the second input terminal is connected to the diagnostic element 562, and the output terminal is connected to the negative electrode side detection unit 522.

In FIG. 17, the switching unit 570 connects the positive power supply unit 531 and the positive detection unit 521 to the positive terminal 211 of the fuel cell stack 1, and connects the negative power supply unit 532 and the negative detection unit 522 to the negative terminal 212. The measurement state to be connected is set.

Specifically, in the current path switch 571, the input terminal connected to the positive power supply unit 531 is connected to the first output terminal connected to the capacitor 511A. As a result, the alternating current I1 output from the positive power supply unit 531 is supplied to the positive terminal 211 of the fuel cell stack 1.

Similarly, in the current path switch 572, the input terminal connected to the negative power supply unit 532 is connected to the first output terminal connected to the capacitor 511B. As a result, the alternating current I2 output from the negative power supply unit 532 is supplied to the negative terminal 212 of the fuel cell stack 1.

In the detection target switching device 573, the output terminal connected to the positive electrode side detection unit 521 is connected to the first input terminal connected to the band pass filter 5211. Accordingly, the resistance component R1 and the capacitance component C1 between the positive electrode terminal 211 and the halfway point terminal 213 of the fuel cell stack 1 are connected in parallel to the positive electrode side detection unit 521. The AC potential Va is output at.

In the detection target switching device 574, the output terminal connected to the negative electrode side detection unit 522 is connected to the first input terminal connected to the band pass filter 5221. As a result, the resistance component R2 and the capacitance component C2 between the negative electrode terminal 212 and the halfway point terminal 213 of the fuel cell stack 1 are connected in parallel to the negative electrode side detection unit 522. The AC potential Vb is output at.

These current

path switching devices

571 and 572 and detection

target switching devices

573 and 574 are both controlled by the diagnosis control unit 580.

The diagnosis control unit 580 corresponds to the diagnosis control unit 80 shown in FIG. The state is switched to a measurement state in which the positive power supply unit 531 and the positive electrode detection unit 521 are connected to the positive electrode terminal 211 of the fuel cell stack 1 or a diagnosis state in which the positive power supply unit 531 and the positive electrode detection unit 521 are connected to the diagnostic element 561.

Further, the diagnosis control unit 580 is in a measurement state in which the negative electrode side power supply unit 532 and the negative electrode side detection unit 522 are connected to the negative electrode terminal 212 of the fuel cell stack 1, or the diagnosis element 562 is connected to the negative electrode side power supply unit 532 and the negative electrode side detection unit 522. Switch to the diagnostic state to connect.

The diagnosis control unit 580 is configured to measure the resistance of the

diagnostic elements

561 and 562 from the measurement state for measuring the impedance of the fuel cell stack 1 from the connection state of the switching unit 570 at a predetermined diagnosis time. Switch to diagnostic state. Thereby, a diagnostic process for diagnosing the measurement state of the impedance measuring device 5b is performed.

When the connection state of the switching unit 570 is switched to the diagnosis state, the diagnosis control unit 580 calculates a diagnosis execution signal for specifying the measurement error of the resistance component R and the reactance component X using the

diagnosis elements

561 and 562. Output to the unit 550.

The diagnosis control unit 580 outputs the diagnosis execution signal to the calculation unit 550, and then specifies the phase of the AC signal output from the AC signal source 546a shown in FIG. Shift. When the computing unit 550 calculates the resistance values of the

diagnostic elements

561 and 562 as the reactance component X, the diagnostic control unit 580 restores the phase of the output signal of the AC signal source 546a.

On the other hand, when receiving the diagnosis execution signal from the diagnosis control unit 580, the arithmetic unit 550 executes a diagnosis process for calculating a measurement error caused by the electronic component of the impedance measuring device 5b using the

diagnosis elements

561 and 562.

In the diagnosis process, the arithmetic unit 550 acquires the resistance component V1r of the AC potential difference signal generated in the diagnostic element 561 from the R component extraction circuit 21 of the positive electrode side detection circuit 5411, and acquires the output current I1 of the positive electrode side power supply unit 531. . Then, the calculation unit 550 calculates the resistance value of the diagnostic element 561 as the measured value R1m based on the acquired resistance component V1r and the output current I. The calculation unit 550 calculates the measurement error of the resistance component R1 based on the calculated measurement value R1m and the reference value Ref1 held in the memory 559.

Further, the calculation unit 550 acquires the resistance component V2r of the AC potential difference signal generated in the diagnostic element 562 from the R component extraction circuit 21 of the negative electrode side detection circuit 5412, and acquires the output current I2 of the negative electrode side power supply unit 532. Then, the arithmetic unit 550 calculates the resistance value of the diagnostic element 562 as the measured value R2m based on the acquired resistance component V2r and the output current I2. The computing unit 550 calculates the measurement error of the resistance component R2 based on the calculated measurement value Rm2 and the reference value Ref2 held in the memory 559.

When the diagnosis control unit 580 shifts the phase of the output signal of the AC signal source 546a by 90 degrees in the delay direction, the X component extraction circuit 22 of the positive detection circuit 5411 detects the AC potential difference generated in the diagnosis element 561. The resistance component V1r is extracted as the reactance component V1x. Further, the X component extraction circuit 22 of the negative-side detection circuit 5412 extracts the resistance component V2r of the AC potential difference generated in the diagnostic element 562 as the reactance component V2x.

The calculation unit 550 acquires the extracted reactance components V1x and V2x, and calculates the reactance values of the

diagnostic elements

561 and 562 as measured values X1m and X2m based on the acquired reactance components V1x and V2x and the output current I1. . The calculation unit 550 calculates measurement errors of the inductance components X1 and X2 based on the calculated measurement values X1m and X2m and the reference values Ref1 and Ref2 of the memory 559.

The calculation unit 550 records the measured values R1m and R2m of the resistance component and the measured values X1m and X2m of the reactance component in the memory 559. The diagnosis control unit 580 outputs the measurement execution signal instead of the diagnosis execution signal when the phase of the output signal of the AC signal source 546a is restored and the connection state of the switching unit 570 is switched to the measurement state. .

When the calculation unit 550 receives the measurement execution signal from the diagnosis control unit 580, the calculation unit 550 executes a correction process for correcting the measurement result based on the measurement value held in the memory 559. Details of the correction processing will be described later with reference to FIG.

In this embodiment, when the measurement error of the reactance component X is specified using resistors as the

diagnostic elements

561 and 562, the phase of the AC signal source 546a is manipulated, but the present invention is not limited to this. For example, as described in FIG. 3, when resistors are used as the

diagnostic elements

561 and 562, the phase of the AC signal source 546 c may be manipulated. Further, when one of the capacitor and the coil is used as the

diagnostic elements

561 and 562, when specifying the measurement error of the resistance component R, the phase of at least one of the

AC signal sources

546a and 546b may be manipulated.

In this embodiment, the

band pass filters

5211 and 5221 are arranged between the

capacitors

511B and 512B and the detection

target switching devices

573 and 574. For example, the

band pass filters

5211 and 5221 are the detection

target switching devices

573 and 574. May be disposed between the positive electrode side detection unit 521 and the negative electrode side detection unit 522.

FIG. 18 is a diagram illustrating a connection state of the switching unit 570 when diagnosing the impedance measuring device 5b.

In the current path switch 571, the input terminal connected to the positive power supply unit 531 is switched from the first output terminal connected to the capacitor 511A to the second output terminal connected to the diagnostic element 561. As a result, the alternating current I1 output from the positive power supply unit 531 is supplied to the diagnostic element 561.

Similarly, in the current path switch 572, the input terminal connected to the negative power supply unit 532 is switched from the first output terminal connected to the capacitor 511B to the second output terminal connected to the diagnostic element 562. As a result, the alternating current I2 output from the negative power supply unit 532 is supplied to the diagnostic element 562.

In the detection target switching unit 573, the output terminal connected to the positive electrode side detection unit 521 is switched from the first input terminal connected to the band pass filter 5211 to the second input terminal connected to the diagnostic element 561. Thereby, since the diagnostic element 561 is connected in parallel to the positive electrode side detection unit 521, the AC potential difference V 1 generated by the diagnostic element 561 is detected by the positive electrode side detection unit 521, and the AC potential difference V 1 is supplied to the AC adjustment unit 540. Is output.

In the detection target switching unit 574, the output terminal connected to the negative electrode side detection unit 522 is switched from the first input terminal connected to the band pass filter 5221 to the second input terminal connected to the diagnostic element 562. Thereby, since the diagnostic element 562 is connected in parallel to the negative electrode side detection unit 522, the AC potential difference V2 generated by the diagnostic element 562 is detected by the negative electrode side detection unit 522, and the AC potential difference V2 is supplied to the AC adjustment unit 540. Is output.

The AC adjustment unit 540 includes the AC current I1 output from the positive power supply unit 531 and the negative power supply unit 532 so that the AC potential difference V1 generated in the diagnostic element 561 and the AC potential difference V2 generated in the diagnostic element 562 are equal to each other. Adjust the amplitude of I2.

The calculation unit 550 receives a current command signal corresponding to the AC current I1 and a current command signal corresponding to the AC current I2 from the AC adjustment unit 540. At the same time, the arithmetic unit 550 receives the positive-side AC potential difference resistance component V1r and the reactance component V1x from the positive-side detection circuit 5411, and the negative-side AC potential difference resistance component V2r and the reactance component from the negative-side detection unit 522. V2x is received.

The calculation unit 550 calculates the resistance value of the diagnostic element 561 based on the AC current I1 and the resistance component V1r of the AC potential difference, and holds the resistance value as the measured value Rm1, as shown in the equation (2-1). Further, calculation unit 550 calculates a resistance value of diagnostic element 562 based on AC current I2 and resistance component V2r of the AC potential difference, and holds the resistance value as measured value Rm2.

Then, the calculation unit 550 calculates the resistance value of the diagnostic element 562 based on the AC current I1 and the reactance component V1x of the AC potential difference, and holds the resistance value as the measured value Xm2, as shown in Expression (3-1). . Further, calculation unit 550 calculates a resistance value of diagnostic element 562 based on AC current I2 and reactance component V2x of the AC potential difference, and holds the resistance value as measured value Xm2.

For example, the calculation unit 550 calculates the difference between the measured value R1m of the diagnostic element 561 and the reference value Ref1 as a measurement error of the resistance component R1, and calculates the difference between the measured value Rm2 of the diagnostic element 562 and the reference value Ref2 as a resistance. Calculated as the measurement error of component R2. The calculation unit 550 calculates the difference between the measured value X1m of the diagnostic element 561 and the reference value Ref1 as a measurement error of the reactance component X1, and calculates the difference between the measured value Xm2 of the diagnostic element 562 and the reference value Ref2 as the reactance component X2. Is calculated as the measurement error.

The calculation unit 550 diagnoses whether the measurement state of the impedance measuring device 5b is good or bad based on the measurement errors of the resistance components R1 and R2, and transmits a diagnosis result regarding the measurement state of the resistance component R to the control unit 6. Further, the calculation unit 550 diagnoses whether the measurement state of the impedance measuring device 5b is good or bad based on the measurement errors of the reactance components X1 and X2, and transmits the diagnosis result regarding the measurement state of the reactance component X to the control unit 6. To do.

For example, the arithmetic unit 550 determines whether or not the measurement error of the diagnostic element 561 and the measurement error of the diagnostic element 562 exceed a predetermined allowable error range. The arithmetic unit 550 determines that the measurement state of the impedance measuring device 5b is good when the measurement errors of the

diagnostic elements

561 and 562 are both within the allowable error range. That is, it is determined that the impedance measurement accuracy has not decreased due to manufacturing variations or deterioration with time of electronic components provided in the impedance measuring device 5b.

When it is determined that the measurement state of the impedance measuring device 5b is good, the calculation unit 550 outputs a diagnosis end signal indicating that the diagnosis is completed to the diagnosis control unit 580. When the diagnosis control unit 580 receives the diagnosis end signal, the diagnosis control unit 580 switches the connection state of the switching unit 570 from the diagnosis state to the measurement state illustrated in FIG.

Then, the calculation unit 550 calculates the resistance component R and the reactance component X of the fuel cell stack 1 in a state where the AC potential difference V1 and the AC potential difference V2 are controlled to be equal to each other by equipotential control, and the calculation result is the control unit. 6 to send.

On the other hand, when the measurement error of the

diagnostic element

561 or 562 exceeds the allowable error range, the calculation unit 550 determines that the measurement state of the impedance measuring device 5b is defective. That is, it is determined that the impedance measurement accuracy is reduced due to manufacturing variations of electronic components provided in the impedance measuring device 5b, deterioration with time, and the like.

When it is determined that the measurement state of the impedance measuring device 5b is defective, the calculation unit 550 stops outputting the diagnosis end signal to the diagnosis control unit 580, for example, and switches the switching unit 570 to the measurement state. Prohibit that.

Alternatively, the calculation unit 550 outputs a diagnosis end signal to the diagnosis control unit 580, switches the switching unit 570 to the measurement state, and determines the resistance of the fuel cell stack 1 based on the measurement error of the

diagnostic elements

561 and 562 calculated at the time of diagnosis. The measurement result of component R may be corrected.

For example, when the measured values of the

diagnostic elements

561 and 562 are smaller than the reference value, the calculation unit 550 adds the measurement error of the diagnostic element 561 to the resistance component R1 that is the measurement result, and also adds the measurement error of the diagnostic element 562 to the resistance component R2. The resistance component R is calculated by adding the measurement error.

Alternatively, the calculation unit 550 may correct the measurement result by adding the average value of the measurement error of the diagnostic element 561 and the measurement error of the diagnostic element 562 to the measurement value of the resistance component R. As another example, when the measurement state is determined to be defective, the calculation unit 550 switches the switching unit 570 to the measurement state and adds the measurement error of the

diagnostic elements

561 and 562 to the measurement result to the control unit 6. You may send it.

Note that the resistance component R and the capacity component C of the fuel cell stack 1 change according to the power generation state of the fuel cell stack 1. For example, when the resistance component R changes, the alternating currents I1 and I2 also change due to equipotential control, so that the measurement error also changes. A method for correcting the measurement result in accordance with such fluctuations of the resistance component R and the capacitance component C will be described with reference to the next figure.

FIG. 19 is an explanatory diagram illustrating an example of a correction method for correcting the resistance component R of the impedance calculated by the calculation unit 550.

FIG. 19 shows a reference characteristic representing a reference value Ref1 of resistance of the diagnostic element 561 and a measurement characteristic determined by the resistance value R1m of the diagnostic element 561 as a measurement result.

When the connection state of the switching unit 570 is switched to the diagnosis state by the diagnosis control unit 580, the calculation unit 550 is based on the output signal V1r of the R component extraction circuit 21 of the positive-side detection circuit 5411 illustrated in FIG. A measured value R1m of the resistance value component of 561 is calculated. And the calculating part 550 calculates the inclination a of the straight line which approximates the measurement characteristic of following Formula (4) using measured value R1m.

Next, when the connection state of the switching unit 570 is switched to the measurement state, the calculation unit 550 calculates the resistance component R1 on the positive electrode side of the fuel cell stack 1 based on the output signal Vr of the R component extraction circuit 21.

Then, the arithmetic unit 550 calculates the correction amount Z by subtracting the measurement characteristic specified by the above expression (4) from the reference characteristic as in the following expression (5).

Specifically, the calculation unit 550 calculates the correction amount Z by substituting the calculated resistance component R1 into the measured value X in the equation (5). The computing unit 50 corrects the resistance component R1 on the positive electrode side of the fuel cell stack 1 by adding the calculated correction amount Z to the resistance component R1.

Thus, the arithmetic unit 550 uses the resistance value R1m of the diagnostic element 561 to correct the measurement result according to the variation of the resistance component R1 of the fuel cell stack 1 that is the measurement object. Similarly, the calculation unit 550 corrects the resistance component R2 on the negative electrode side using the resistance value R2m of the diagnostic element 562. Although the method for correcting the resistance component R has been described here, the same applies to the case where the reactance component X is corrected. Thereby, the measurement accuracy of the impedance measuring device 5b can be further increased.

Next, the operation of the impedance measuring device 5b will be described with reference to FIG.

FIG. 20 is a flowchart showing an example of a processing method of the impedance measuring apparatus 5b in the present embodiment.

First, in step S201, the diagnosis control unit 580 determines whether or not it is a diagnosis time for the impedance measuring device 5b to diagnose its own state. The diagnosis control unit 580 supplies a diagnosis execution signal to the calculation unit 550 when determining that the diagnosis time has come. On the other hand, when it is determined that the diagnosis time has not come, the diagnosis control unit 580 supplies a measurement execution signal to the calculation unit 550 instead of the diagnosis execution signal.

In step S202, when the diagnosis time comes, the diagnosis control unit 580 controls the

current path switchers

571 and 572 so that the positive power supply unit 531 and the negative power supply unit 532 are connected to the

diagnostic elements

561 and 562, respectively. Connecting. At the same time, the diagnosis control unit 580 controls the detection

target switching devices

573 and 574 to connect the

diagnosis elements

561 and 562 in parallel to the positive electrode side detection unit 521 and the negative electrode side detection unit 522, respectively.

As described above, when the impedance measuring device 5b reaches the diagnosis time, the diagnosis control unit 580 supplies the alternating currents I1 and I2 to the

diagnostic elements

561 and 562, respectively, so that the AC potential differences V1 and V2 generated in the

diagnostic elements

561 and 562 are obtained. Switch to the diagnostic state to detect.

In step S203, the diagnosis control unit 580 sets the alternating currents I1 and I2 output from the positive power supply unit 531 and the negative power supply unit 532 to initial values. The initial values of the alternating currents I1 and I2 are set based on the current values of the alternating currents I1 and I2 when the alternating current potential difference V1 and the alternating current potential difference V2 match in the diagnosis state.

For example, the diagnosis control unit 580 switches the reference value Vs of the reference power source 545 shown in FIG. 10 to the vector value Vp1 output from the vector calculation unit 23 shown in FIG. 11 as an initial value.

Thus, even when the alternating currents I1 and I2 reach the upper limit value of the fluctuation range and are switched to the diagnosis state, the alternating potential differences V1 and V2 can be quickly converged to the reference voltage Vs. Therefore, the diagnosis time can be shortened.

In the state where the alternating currents I1 and I2 are adjusted so that the alternating current potential differences V1 and V2 are equal to each other by the alternating current adjustment unit 540, the alternating current potential differences V1 and V2 are detected from the positive electrode side detection unit 521 and the negative electrode side detection unit 522. 5411 and the negative electrode side detection circuit 5412.

In step S204, upon receiving the diagnosis execution signal from the diagnosis control unit 580, the calculation unit 550 measures the resistance values R1m and R2m of the

diagnosis elements

561 and 562, respectively. In the present embodiment, the arithmetic unit 550 uses the alternating currents I1 and I2 and the resistance components V1r and V2r of the AC potential difference as shown in the equation (2-1) to calculate the resistance value R1m of the diagnostic element 561 and the diagnostic element 562. The resistance value R2m is calculated.

In step S205, when the resistance values R1m and R2m of the

diagnostic elements

561 and 562 are calculated, the diagnosis control unit 580 calculates the phase of the output currents I1 and I2 of the positive power supply unit 531 and the negative power supply unit 532 shown in FIG. To operate. In the present embodiment, the diagnosis control unit 580 shifts the phase of the AC signal output from the AC signal source 546a shown in FIG. 10 by 90 degrees from 0 degrees in the delay direction. As a result, the phases of the AC potential difference signals V1 and V2 output from the positive electrode side detection unit 521 and the negative electrode side detection unit 522 are delayed by 90 degrees, so that the X component extraction circuit 22 of the positive electrode side detection circuit 5411 and the negative electrode side detection circuit 5412 Thus, it is possible to extract the AC potential difference generated in the

diagnostic elements

561 and 562, respectively.

In step S206, the arithmetic unit 550 changes reactance values X1m and X2m corresponding to the resistance values of the

diagnostic elements

561 and 562 after changing the phases of the alternating currents I1 and I2. In the present embodiment, the calculation unit 550 acquires the reactance component V1x of the AC potential difference from the X component extraction circuit 22 of the positive electrode side detection circuit 5411 and the reactance component V2x of the AC potential difference from the X component extraction circuit 22 of the negative electrode side detection circuit 5412. To get. Then, the arithmetic unit 550 calculates the resistance values of the

diagnostic elements

561 and 562 as reactance values X1m and X2m based on the reactance components V1x and V2x of the AC potential difference.

In step S207, when the reactance values X1m and X2m are calculated using the

diagnostic elements

561 and 562, the diagnosis control unit 580 restores the phases of the alternating currents I1 and I2. In the present embodiment, the diagnosis control unit 580 sets the phase of the AC signal output from the AC signal source 546a to 0 degrees.

In step S208, the calculation unit 550 executes a diagnosis process for diagnosing whether or not the measurement state of the impedance measuring device 5b is good.

In the present embodiment, the calculation unit 550 calculates the measurement error between the measurement values R1m and X1m related to the diagnostic element 561 and the reference value Ref1, and calculates the measurement error between the measurement values R2m and X2m related to the diagnostic element 562 and the reference value Ref2. To do. The calculation unit 550 determines whether or not these measurement errors are both within the allowable error range. If both the measurement errors of the

diagnostic elements

561 and 562 are within the allowable error range, the arithmetic unit 550 determines that the measurement state of the impedance measuring device 5b is good, and returns to step S201.

On the other hand, in step S209, when the measurement error of the

diagnostic element

561 or 562 is outside the allowable error range, the calculation unit 550 determines that the measurement state is defective and sends a diagnosis result indicating that to the control unit 6. Output. Thereby, the reliability of the impedance measuring device 5b can be ensured.

Next, if it is determined in step S201 that it is not the diagnosis time, the process proceeds to step S210.

In step S210, the diagnosis control unit 580 controls the current

path switching units

571 and 572 to connect the positive electrode side power source unit 531 and the negative electrode side power source unit 532 to the positive electrode terminal 211 and the negative electrode terminal 212 of the fuel cell stack 1, respectively. . At the same time, the diagnosis control unit 580 controls the detection

target switching devices

573 and 574 to connect the resistance component R1 between the positive electrode terminal 211 and the halfway point terminal 213 to the positive electrode side detection unit 521, and at the same time, the negative electrode terminal 212. And a resistance component R2 between the halfway point terminal 213 and the negative electrode side detection unit 522.

As described above, the diagnosis control unit 580 supplies the alternating currents I1 and I2 to the fuel cell stack 1, respectively, and uses the combined component of the resistance component R1 and the capacitance component C1 and the combined component of the resistance component R2 and the capacitance component C2. It switches to the measurement state which detects the alternating current potential difference V1 and V2 which arise. Then, the AC adjustment unit 540 controls the positive power supply unit 531 and the negative power supply unit 532 so that the AC potential differences V1 and V2 are equal to each other, thereby adjusting the amplitudes of the AC currents I1 and I2.

In this state, 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 positive electrode side detection circuit 5411 and the negative electrode side detection circuit 5412, respectively. Then, the resistance component V1r and reactance component V1x from the positive electrode side detection circuit 5411 and the resistance component V2r and reactance component V2x from the negative electrode side detection circuit 5412 are input to the arithmetic unit 550. In addition, current command signals output from the AC adjustment unit 540 to the positive power supply unit 531 and the negative power supply unit 532 are output to the calculation unit 550 as AC currents I1 and I2.

In step S211, the calculation unit 550 measures the resistance components R1 and R2 of the impedance of the fuel cell stack 1 and the reactance components C1 and C2.

In the present embodiment, the arithmetic unit 550 uses the adjusted AC currents I1 and I2 and the AC voltage difference resistance components V1r and V2r as shown in the equation (2-1), and the resistance components R1 and R2 of the fuel cell stack 1 R2 is calculated. Further, the calculation unit 550 calculates the reactance components X1 and X2 of the fuel cell stack 1 using the adjusted AC currents I1 and I2 and the reactance components V1x and V2x of the AC potential difference as shown in Expression (3-1). To do.

In step S212, the calculation unit 550 executes a correction process for correcting the measurement result calculated in step S208 using the measurement error calculated in steps S203 and S205.

In the present embodiment, as described with reference to FIG. 19, the calculation unit 550 calculates the correction amount Z by inputting the resistance component R1 that is the measurement result to the measurement value X of Equation (5), and calculates the correction amount Z. Add to the resistance component R1. Similarly, correction amounts corresponding to the resistance component R2 and the reactance components X1 and X2 that are measurement results are added.

In step S213, the calculation unit 550 outputs the corrected measurement result to the control unit 6 that is the transmission destination.

In the present embodiment, the calculation unit 550 calculates the resistance component R of the entire fuel cell stack 1 by synthesizing the corrected resistance components R1 and R2 as shown in Expression (2-2). Further, the calculation unit 550 calculates the reactance component X of the entire fuel cell stack 1 by combining the corrected reactance components X1 and X2 as shown in Expression (3-2). Then, the calculation unit 550 transmits the combined resistance component R and reactance component X to the control unit 6 as measurement results.

When it is determined in step S209 that the measurement error of the

diagnostic elements

561 and 562 exceeds the allowable error range, the calculation unit 550 adds measurement data indicating the measurement error to the measurement result. May be generated and transmitted to the control unit 6.

In step S214, the calculation unit 550 repeatedly executes a series of processing steps from step S201 to step S213 until the operation of the impedance measuring device 5b is stopped (OFF). When the impedance measuring device 5b is stopped, the processing method is terminated.

In this embodiment, the

diagnostic elements

561 and 562 are mounted on each of the two systems of the positive electrode side measurement path and the negative electrode side measurement path. However, the measurement error caused by the electronic components in both measurement paths is 1 You may make it diagnose by combining one diagnostic element. In this case, in the diagnosis state, the positive power supply unit 531 and the positive detection unit 521, and the negative power supply unit 532 and the negative detection unit 522 are sequentially connected to one diagnostic element.

For example, in the diagnosis state, the diagnosis control unit 580 disconnects the connection with the positive terminal 211 and connects the positive power supply unit 531 and the positive detection unit 521 to one diagnostic element. Thereafter, the connection with the negative electrode terminal 212 is disconnected, and the negative electrode side power supply unit 532 and the negative electrode side detection unit 522 are connected to the same diagnostic element. This eliminates errors caused by variations between the positive and negative systems, specifically, variations in diagnostic elements and switches, so that the accuracy of measuring measurement errors in each system can be improved.

In the present embodiment, the diagnosis control unit 580 outputs a diagnosis execution signal to the calculation unit 550 in order to diagnose the measurement accuracy of the impedance measurement device 5b at the time of manufacturing, shipping inspection, and periodic inspection of the impedance measurement device 5b. To do. As a result, the diagnosis control unit 580 switches the switching unit 570 to the diagnosis state, and the calculation unit 550 calculates the impedance measurement error of the

diagnostic elements

561 and 562.

Usually, in order to adjust the manufacturing variation of the impedance measuring device 5b within an allowable range, an operator uses the adjustment equipment to perform shipping inspection and calibration of the impedance measuring device 5b. On the other hand, it is programmed to execute diagnostic processing at the time of manufacturing, shipping inspection, and periodic inspection of the impedance measuring device 5b, thereby automatically determining pass / fail of the shipping inspection and periodic inspection and the measurement function. Calibration can be performed.

For example, the diagnosis execution signal is output from the operation switch unit 6a shown in FIG. The operation switch unit 6a is a switch or button that can be operated from the outside. The operation switch unit 6a is provided with an inspection switch for executing diagnosis and calibration (correction) of the impedance measuring device 5b. When the inspection switch is set to ON by an operator, the operation switch unit 6a performs diagnosis. An execution signal is output to the control unit 6. The control unit 6 outputs a diagnosis execution signal to the diagnosis control unit 580 via the calculation unit 550.

By doing in this way, the adjustment work at the time of manufacture and the work of the periodic inspection can be reduced while maintaining the measurement accuracy of the impedance measuring device 5b. Note that a diagnosis execution signal may be output from the operation switch unit 6a by attaching or removing a jumper wire to or from the operation switch unit 6a.

According to the second embodiment of the present invention, the diagnosis control unit 580, in the diagnosis state, extracts the reactance component X1 using the diagnosis element 561 that is a resistor, the AC current I1 and the positive-side orthogonal shift. The phase of at least one of the output signals of the phase shifter 41 is shifted. Similarly, when the diagnosis control unit 580 extracts the reactance component X2 using the diagnosis element 562 that is a resistor, the diagnosis control unit 580 outputs at least one AC signal of the AC current I2 and the output signal of the negative-phase quadrature phase shifter 41. Shift phase.

Thereby, by using one diagnostic element 561, not only the measurement error of the resistance component R1 but also the measurement error of the reactance component X1 in the measurement path on the positive electrode side can be specified. For this reason, since the number of diagnostic elements mounted on the impedance measuring device 5b can be reduced, the measurement accuracy of both the resistance component R and the reactance component X is improved while suppressing an increase in the scale of the impedance measuring device 5b. be able to.

Further, according to the present embodiment, the diagnosis control unit 580 uses the resistor as the diagnosis element 60 to extract the reactance components V1x and V2x by the X component extraction circuit 22 of both the positive detection circuit 5411 and the negative detection circuit 5412. In the case of extraction, the phase of one AC signal source 546a is shifted by 90 degrees.

Therefore, as compared with the case where the phases of the two AC signal sources 546c of the positive electrode side detection circuit 5411 and the negative electrode side detection circuit 5412 are operated by 90 degrees, it is only necessary to operate the phase of one AC signal source 546a. Operation can be simplified.

Further, according to the present embodiment, when the diagnosis control unit 580 uses the resistor as the diagnostic element 60 to extract the reactance components V1x and V2x by the X component extraction circuit 22, the diagnosis control unit 580 determines each phase of the AC signal source 546c. Manipulate. Since the output of the AC signal source 546c is smaller than the outputs of the positive power supply unit 531 and the negative power supply unit 532, the phase operation is accompanied by the phase operation as compared with the case of operating the phases of the positive power supply unit 531 and the negative power supply unit 532. The influence of noise can be reduced.

Further, according to the present embodiment, the alternating current adjusting unit 540 adjusts the amplitudes of the alternating currents I1 and I2 so that the alternating current potential difference V1 and the alternating current potential difference V2 coincide with each other. Therefore, when the switching unit 570 is switched to the diagnosis state, the diagnosis control unit 580 sets the alternating currents I1 and I2 output from the positive power supply unit 531 and the negative power supply unit 532 to initial values.

This makes it possible to shorten the time required to adjust the amplitudes of the alternating currents I1 and I2 so that the alternating potential differences V1 and V2 coincide at the start of diagnosis. Therefore, an increase in time associated with the phase operation of the alternating currents I1 and I2 can be suppressed.

In addition, the fuel cell stack 1 has electrical characteristics such as charge transfer resistance, electric double layer capacity and internal loss resistance related to power generation of the fuel cell. In this embodiment, since the internal loss resistance component included in the internal impedance of the fuel cell stack 1 has a high correlation with the wet state of the electrolyte membrane 111, the resistance component R of the fuel cell stack 1 is measured by the impedance measuring device 5b. . On the other hand, in order to measure the charge transfer resistance and the capacitance component of the electric double layer capacity included in the impedance of the fuel cell stack 1, measurement is performed by changing the frequencies of the alternating currents I1 and I2 supplied to the fuel cell stack 1. be able to. The capacity component of the internal impedance changes according to the concentration of hydrogen contained in the anode gas in the fuel cell stack 1. Since the electrolyte membrane deteriorates when the hydrogen concentration in the fuel cell stack 1 is insufficient, the lack of hydrogen in the fuel cell stack 1 can be diagnosed by using the measured value of the capacity component C of the fuel cell stack 1. It becomes possible.

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.

For example, in the above embodiment, the phases of the oscillation circuits 40a to 40c or the AC signal sources 546a to 546c are manipulated, but the phases of these signal sources are fixed, and the phase of the output signal from the signal source is changed for each signal source. You may make it provide the phase shifter to make.

Further, in the present embodiment, the AC adjustment unit 540 is configured by an analog circuit, but may be configured by a digital arithmetic unit such as a microcomputer chip.

Furthermore, in the second embodiment, the measurement object 10 is the fuel cell stack 1, but may be a lithium ion battery. As long as the resistance on the positive electrode side and the negative electrode side hardly changes, the circuit configuration of the impedance measuring device 5b may be simplified. For example, the AC adjustment unit 540 is omitted, and the AC currents I1 and I2 whose amplitude and phase coincide with each other 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 resistance component R of the fuel cell stack 1, and the alternating current adjustment unit 540 causes the alternating current potentials V1 and V2 to have the same reference value Vs. An example of controlling the amplitudes of I1 and I2 has been described. However, the midpoint terminal 213 may be provided in a power generation cell that is out of the power generation cell located in the middle of the fuel cell stack 1. In this case, since the AC potential generated at the positive electrode terminal 211 and the AC potential generated at the negative electrode terminal only need to coincide with each other, the resistance component R1 and the resistance component R2 depend on the position of the power generation cell provided with the halfway point terminal 213. What is necessary is just to obtain | require resistance ratio and to set the reference value of the amplitude of AC electric potential difference V1 and V2 according to the resistance ratio.

In addition, the said embodiment can be combined suitably.

Claims

A power supply circuit that outputs an alternating current to the measurement target;
An arithmetic unit that calculates the impedance of the measurement object based on the AC potential difference generated in the measurement object and the output current of the power supply circuit;
Any one passive element of a resistor, a capacitor, and a coil for specifying the impedance error; and
A switch for switching between a measurement state in which the measurement target is connected to the power supply circuit and a diagnosis state in which the passive element is connected to the power supply circuit;
A processing method for an impedance measuring device including:
An output step of outputting an alternating current to the measurement object by the power supply circuit;
A detection step of detecting an AC potential difference generated in the measurement object;
A first oscillation step for outputting an AC signal having the same frequency as the output current of the power supply circuit;
A first extraction step of extracting a resistance component of the AC potential difference detected in the detection step based on an output signal in the first oscillation step;
A second oscillation step for outputting an AC signal having a phase orthogonal to the output signal in the first oscillation step;
A second extraction step of extracting a reactance component of the AC potential difference detected in the detection step based on an output signal in the second oscillation step;
A calculation step of calculating a resistance component or reactance component of the impedance of the measurement object based on the component extracted in the first or second extraction step and the alternating current output in the output step;
When the switch is switched to the diagnosis state, when the reactance component is extracted in the second extraction step, the output step and the first oscillation are compared to when the resistance component is extracted in the first extraction step. A phase shifting step of shifting the phase of the output signal corresponding to the passive element among the output signals in the step and the second oscillation step;
When the switch is switched to the diagnosis state, based on each component extracted in the first and second extraction steps, a process for diagnosing an error in the impedance calculated in the calculation step, or the impedance A processing step for executing a correction process;
A processing method for an impedance measuring device including:
It is a processing method of the impedance measuring device according to claim 1,
The passive element is a resistor having a resistance of a reference value,
In the phase shifting step, when a reactance component is extracted in the second extraction step using the resistor, at least one of the AC signals output in the output step and the second oscillation step Shift the phase by a certain angle,
Processing method of impedance measuring device.
It is a processing method of the impedance measuring device according to claim 2,
The phase shift step shifts the phase of the alternating current output in the output step by 45 degrees or 90 degrees when the reactance component is extracted in the second extraction step using the resistor.
Processing method of impedance measuring device.
It is a processing method of the impedance measuring device according to claim 2,
The phase shifting step shifts the phase of the AC signal output in the second oscillation step by 90 degrees when the reactance component is extracted in the second extraction step using the resistor.
Processing method of impedance measuring device.
It is a processing method of the impedance measuring device according to any one of claims 1 to 4,
The power supply circuit outputs the alternating current to each of the positive electrode and the negative electrode of the laminated battery to be measured,
The detecting step includes
A positive electrode side detection step for detecting an AC potential difference between the middle point of the laminated battery and the positive electrode;
A negative electrode side detection step for detecting an AC potential difference between the negative electrode of the multilayer battery and the midpoint,
In the first extraction step, based on the output signal in the first oscillation step, the resistance component of the AC potential difference detected in the positive electrode side detection step and the negative electrode side detection step is extracted,
In the second extraction step, based on the output signal in the first oscillation step, each of the capacitance components of the AC potential difference detected in the positive electrode side detection step and the negative electrode side detection step is extracted,
The amplitude of the AC current output from the power supply circuit to the positive electrode or the negative electrode of the stacked battery so that the AC potential difference detected in the positive electrode side detection step matches the AC potential difference detected in the negative electrode side detection step. Adjustment steps to adjust,
When the switch is switched to the diagnostic state, the initializing step of setting the alternating current output from the positive power supply circuit and the negative power supply circuit to initial values by the adjustment step, respectively,
Processing method of impedance measuring device.
It is a processing method of the impedance measuring device according to any one of claims 1 to 5,
The processing step includes
When the switch is switched to the diagnostic state, based on the component extracted by the first extraction circuit or the second extraction circuit and the alternating current output from the power supply circuit, the computing unit A calculation step for calculating a resistance component or reactance component of the impedance;
When the difference between the resistance component or reactance component calculated in the calculation step and the reference value determined by the passive element exceeds a predetermined threshold, the measurement state of the impedance measuring device is diagnosed as defective Including a diagnostic step,
Processing method of impedance measuring device.
It is a processing method of the impedance measuring device according to any one of claims 1 to 6,
The processing step includes
When the switch is switched to the diagnostic state, based on the component extracted in the first extraction step or the second extraction step and the alternating current output in the output step, the computing unit A calculation step for calculating a resistance component or reactance component of the impedance;
An error calculating step of calculating a measurement error that is a difference between the resistance component or reactance component calculated in the calculating step and a reference value determined by the passive element;
A correction step of correcting the resistance component or reactance component of the impedance calculated in the calculation step based on the measurement error calculated in the error calculation step when the switch is switched to the measurement state; Including,
Processing method of impedance measuring device.
A power supply circuit that outputs an alternating current to the measurement target;
A detection circuit for detecting an AC potential difference generated in the measurement object;
A first oscillation circuit that outputs an AC signal having the same frequency as the output current of the power supply circuit;
A first extraction circuit that extracts a resistance component of an AC potential difference detected by the detection circuit based on an output signal of the first oscillation circuit;
A second oscillation circuit that outputs an AC signal whose phase is orthogonal to the output signal of the first oscillation circuit;
A second extraction circuit for extracting a reactance component of the AC potential difference detected by the detection circuit based on an output signal of the second oscillation circuit;
An arithmetic unit that calculates a resistance component or a reactance component of an impedance of the measurement object based on a component extracted by the first extraction circuit or the second extraction circuit and an alternating current output by the power supply circuit; ,
Any one passive element of a resistor, a capacitor, and a coil for specifying an error in impedance calculated by the calculator;
A switch for switching between a measurement state in which the measurement target is connected to the power supply circuit and a diagnosis state in which the passive element is connected to the power supply circuit;
A control unit for controlling a connection state of the switch,
In the case where the switch is switched to the diagnosis state, the control unit extracts the reactance component by the second extraction circuit, compared with the case of extracting the resistance component by the first extraction circuit, Shifting the phase of the output signal of the circuit corresponding to the passive element among the first oscillation circuit and the second oscillation circuit,
The computing unit diagnoses an error in the impedance of the measurement object or corrects the impedance based on each component extracted by the first extraction circuit and the second extraction circuit using the passive element. ,
Impedance measuring device.