JP2010231973A - Electrochemical system and load connection/disconnection method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical system capable of performing decision of deterioration in a short period of time and achieving low capacity of a power supply for backing up decision work. <P>SOLUTION: In the electrochemical system having an electrochemical device 10, a connection/disconnection device 22 for connecting and disconnecting between the electrochemical device 10 and external load 15, and a voltage detection sensor 20 for detecting a voltage of the electrochemical device 10, the electrochemical system has a load disconnection means for disconnecting between the electrochemical device 10 and the external load 15 at required timing by the connection/disconnection device 22, a voltage acquisition means for making voltage of the electrochemical device acquire by the voltage detection sensor 20 when disconnecting the external load 15, a voltage change speed calculation means for calculating voltage change speed of the electrochemical device 10 when disconnecting the external load 15, and a load connection means for connecting the external load 15 with the electrochemical device 10 by the connection/disconnection device 22 on the basis of the calculated voltage change speed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrochemical system using, for example, an SOFC or a secondary battery, and a load disconnecting method of the electrochemical system.

As this type of electrochemical system, there is one having a configuration disclosed in Patent Document 1 under the name of a fuel concentration detection method for a direct methanol fuel cell.
The electrochemical system described in Patent Document 1 includes a steady-state voltage measurement step for measuring a steady-state output voltage of the fuel cell in a state in which a current flows to an electrical load connected to the fuel cell, and the fuel A load switching step for reducing the current flowing from the battery to the electric load to substantially zero; and the fuel cell at a time after a predetermined time has elapsed since the current flowing to the electric load was reduced to substantially zero. A no-load voltage measuring step for measuring the no-load output voltage, a concentration calculation step for obtaining the methanol concentration from the relationship between the no-load output voltage and the methanol concentration of the fuel supplied to the fuel cell; It is characterized by having.

JP 2005-285628 A

  However, in the conventional electrochemical system described in Patent Document 1, since the time during which the current is cut off is long, the power generation request from the outside cannot be satisfied, and therefore the current is cut off. In the meantime, there is a drawback that the capacity of the power storage means for satisfying the power generation request from the outside must be increased.

  Therefore, the present invention provides an electrochemical system capable of determining degradation in a short time and reducing the capacity of a power source for backing up the same, and a load disconnecting method for the electrochemical system. It is aimed.

  In order to achieve the above object, an electrochemical system according to the present invention includes an electrochemical device, a disconnector for disconnecting the electrochemical device from an external load, and a voltage of the electrochemical device. Voltage detection sensor, and at the required timing, the voltage separating means for separating the electrochemical device and the external load with a disconnector and the voltage of the electrochemical device when the external load is disconnected are detected. Voltage acquisition means to be acquired by the sensor, voltage change rate calculation means for calculating the voltage change rate of the electrochemical device when the external load is disconnected based on the acquired voltage value of the electrochemical device, and the calculated voltage change rate And a load connecting means for connecting an external load to the electrochemical device by a disconnector.

  In order to achieve the above object, a load disconnecting method of an electrochemical system according to the present invention includes an electrochemical device, a disconnector for disconnecting the electrochemical device and an external load, and the electrochemical device. A load disconnecting method for an electrochemical system having a voltage detection sensor for detecting a voltage of a load, the load disconnecting step for disconnecting the electrochemical device and the external load by a disconnector at a required timing, and an external Based on the voltage acquisition step of acquiring the voltage of the electrochemical device when the load is disconnected by the voltage detection sensor and the acquired voltage value of the electrochemical device, the voltage change rate of the electrochemical device when the external load is disconnected is calculated. A voltage change rate calculation step to be calculated, and a load connection step of connecting an external load to the electrochemical device by a disconnector based on the calculated voltage change rate. It has a Rukoto the contents.

  According to the present invention, degradation can be determined in a short time, and the capacity of a power source for backing up the degradation can be reduced.

It is a block diagram which shows the structure of the electrochemical system which concerns on 1st embodiment of this invention. It is a block diagram which shows the function of the control unit which makes a part of electrochemical system same as the above. It is a graph which shows the relationship between the output voltage of a stack, and time. It is a graph which shows the relationship between the output voltage and current of a stack. It is a detailed flowchart of the load connection / disconnection method of an electrochemical system same as the above. It is a block diagram which shows the structure of the electrochemical system which concerns on 2nd embodiment of this invention. It is a block diagram which shows the structure of the electrochemical system which concerns on 3rd embodiment of this invention. It is a block diagram which shows the structure of the electrochemical system which concerns on 4th embodiment of this invention. It is a detailed flowchart of the load connection / disconnection method of an electrochemical system same as the above. It is a block diagram which shows the structure of the electrochemical system which concerns on 5th embodiment of this invention. It is a detailed flowchart of the load connection / disconnection method of an electrochemical system same as the above.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated with reference to drawings. FIG. 1 is a block diagram showing a configuration of an electrochemical system according to the first embodiment of the present invention, and FIG. 2 is a block diagram showing functions of a control unit forming a part of the electrochemical system.
3 is a graph showing the relationship between stack output voltage and time, and FIG. 4 is a graph showing the relationship between stack output voltage and current.

  The electrochemical system A1 according to the first embodiment of the present invention supplies electric power from the electrochemical device 10 to an external load 15 such as a motor connected to the electrochemical device 10, and the electrochemical device 10 or the external In addition to the load 15, a voltmeter 20, an ammeter 21, a device temperature sensor S 1, a relay 22, an inverter 23, a control unit 30, and the like are configured.

The electrochemical apparatus 10 shown in the present embodiment is configured to include a fuel reformer (not shown) and the like in addition to the fuel cell 11 as an electrochemical device.
The fuel cell 11 includes a solid oxide fuel cell stack (hereinafter simply referred to as “stack”) 12.
The stack 12 is formed by stacking a plurality of cell units 13... And is accommodated in a case 14.

Each cell unit 13 includes a solid oxide cell (both not shown) in which a fuel electrode and an air electrode are provided on both sides of the electrolyte membrane, and the fuel electrode and the air electrode include air and Power generation is performed by separating fuel gases from each other and flowing them.
The cell unit 13 is provided with a device temperature sensor S1 (see FIG. 2), and detects the temperature of the cell unit 13, and hence the temperature of the fuel cell 11.

One of the output terminals 12a and 12b (see FIG. 1) of the stack 12 is provided with the ammeter 21 for measuring current, and the voltage is measured between the output terminals 12a and 12b. The above-described voltmeters 20 are provided.
The ammeter 21 and the voltmeter 20 are connected to the input port side of the control unit (hereinafter abbreviated as “C / U”) 30 so that the measured values of the acquired outputs are input. It has become.
In the present embodiment, the ammeter 21 and the voltmeter 20 described above are output measuring instruments for measuring the output of the fuel cell 11.
The inverter 23 is for converting the DC power output from the fuel cell 11 into AC and supplying power to an external load (hereinafter referred to as “motor”) 15.

  Reference numeral 24 denotes a fuel pump for supplying fuel necessary for power generation toward the fuel electrode of the fuel cell 11, and reference numeral 25 denotes an air blower for supplying air necessary for the air electrode. It is connected to the output port side of U30 and is appropriately driven.

  As shown in FIG. 2, the C / U 30 includes a central control unit 31 including a CPU (Central Processing Unit), an interface circuit and the like (all not shown), and a memory 32 including a hard disk and a semiconductor memory. is there.

  By executing the program used for the fuel cell system A1 stored in the memory 32, the C / U 30 and, therefore, the central control unit 31 performs the following functions.

A function of separating the fuel cell 11 and the motor 15 by the relay 22 at a required timing. This function is referred to as “load separation means 31a”.

A function of causing the voltmeter 20 to acquire the voltage of the fuel cell 11 when the motor 15 is disconnected. This function is referred to as “voltage acquisition means 31b”.

A function of calculating the voltage change rate of the fuel cell 11 when the motor 15 is disconnected based on the acquired voltage value of the fuel cell 11. This function is referred to as “voltage change rate calculation means 31c”.
That is, as shown in FIG. 3, the voltage change after the motor 15 is disconnected can be divided into a part where the voltage change rate does not change and a part where the voltage change rate is gradually reduced by half.
The portion where the voltage change rate does not change is an internal resistance component having a quick response since it occurs after the motor 15 is disconnected, that is, immediately after the current is interrupted.
As shown in FIG. 4, this portion can be classified into internal resistance (IR resistance) caused by ohmic loss. The breakdown of the IR resistance component is considered to consist of the ion conduction resistance of the electrolyte membrane, the electron conduction resistance of the contact configuration connecting the fuel electrode and the air electrode, and the like.

On the other hand, the portion where the voltage change rate gradually changes is an internal resistance component having a slow response because it occurs for a while after the current is interrupted. This part can be classified into internal resistance resulting from electrochemical reaction resistance. In the present embodiment, when the IR resistance region is measured, the motor 15 is connected to the fuel cell 11 by the relay 22 to return to the normal operation.
At this time, in practice, it is difficult to clearly distinguish a region where the voltage change rate is constant from a region where the voltage change rate changes gradually. Therefore, the two regions are distinguished from each other by determining whether or not the amount of change in the voltage change rate has reached a certain value determined according to each device.
The determination of the fixed value can be set by, for example, examining the breakdown of the internal resistance of the electrochemical device in advance and comparing the behavior when a similar current interruption is performed.
As described above, in this embodiment, the IR resistance can be measured.

-A function that determines whether or not the amount of change in the voltage change rate has exceeded a certain level. This function is referred to as “transition amount determination means 31d”.

A function of connecting the motor (external load) 15 to the fuel cell (electrochemical device) 10 by the disconnector 22 based on the calculated voltage change rate. This function is referred to as “load connection means 31e”.
In the present embodiment, the motor 15 is connected to the fuel cell 11 by the relay 22 when it is determined that the amount of change in the voltage change speed is equal to or greater than a certain value.

A function that calculates the internal resistance based on the current change rate, the current-voltage during power generation, or the open-circuit voltage during startup. This function is referred to as “internal resistance calculation means 31f”.
In the present embodiment, the internal resistance is calculated according to a preset schedule. However, the internal resistance may be calculated according to a power request signal from the outside. The “preset schedule” is stored in the memory 32 and is read when the internal resistance value is calculated.
That is, the history of the deterioration state is stored in the C / U 30, and operations such as prediction of the maintenance time and transmission of a warning can be performed.
Further, “in response to an external power request signal” means, for example, when the power generation request to the system becomes zero (for example, in the case of a vehicle fuel cell system, when the driver turns off the accelerator) Perform internal resistance diagnosis.

  For example, in the case of a fuel cell, the internal resistance of this fuel cell (a phenomenon that generates energy loss with respect to the theoretical free energy that can be extracted from the fuel cell reaction) is the IR resistance, reaction resistance, and fuel component permeation through the electrolyte membrane. Can be divided into three types of cross leaks. Furthermore, the open circuit voltage varies according to the concentration of the fuel component and the oxidizing gas component. At this time, the internal resistance can be separated and grasped according to the following procedure.

  First, an open circuit voltage is measured when an open circuit is made with fuel supplied, such as at the start of operation. This open circuit voltage can be expressed as [Equation 1]. Here, the first term on the right side of [Formula 1] can be obtained from the thermodynamic constant corresponding to the operating temperature. The operating temperature can be obtained with a thermometer incorporated in the device. The second term on the right side of [Formula 1] is derived from the hydrogen partial pressure at the outlet of the fuel reformer, the water vapor partial pressure, and the oxygen partial pressure in the introduced air, which are estimated from the fuel flow rate, the reformer temperature. be able to. When the actually measured open circuit voltage is smaller than the value on the right side of [Equation 1] obtained as described above, the difference is defined as a voltage loss due to cross leakage.

  On the other hand, the difference (Er) between the open circuit voltage and the voltage measured immediately before the current interruption is the sum of the voltage drops caused by the IR resistance and the reaction resistance. A value obtained by multiplying the above-described IR resistance by the current value immediately before current interruption is an IR loss voltage. The value obtained by subtracting the IR loss voltage from Er is the reaction resistance loss voltage (see FIG. 4).

  In Equation 2, ΔG ° is the Gibbs production energy corresponding to [Equation 3], and the superscript (0) indicates that all substances included in the reaction are under 1 atm.

  With the above configuration, the IR resistance and reaction resistance can be changed by controlling the power generation system. For example, IR resistance decreases with decreasing temperature. The reaction resistance decreases as the fuel or oxygen concentration increases or the temperature increases. That is, according to the internal resistance diagnosis shown on the left, when the IR resistance increases, the reaction resistance can be reduced by performing control for increasing the FC operating temperature (for example, control for decreasing the cathode air flow rate). When the reaction resistance increases, control for increasing the excess fuel ratio (for example, control for increasing the cathode air flow rate) or control for increasing the FC operating temperature can be performed. Such control can keep the system operating properly.

A function of acquiring the temperature of the fuel cell (electrochemical device) 11 by the device temperature sensor S1. This function is referred to as “apparatus temperature acquisition means 31g”.

A function for increasing / decreasing the internal resistance value based on the acquired temperature of the fuel cell 11. This function is referred to as “internal resistance correction means 31h”.
Specifically, when the voltage loss due to the IR resistance increases, the reaction resistance can be reduced by performing control for increasing the operating temperature of the fuel cell 11 (for example, control for decreasing the cathode air flow rate).
When the reaction resistance increases, control for increasing the excess fuel ratio (for example, control for increasing the cathode air flow rate) can be performed. By such control, the operation state of the electrochemical system A1 can be properly maintained.
That is, among the IR resistance components, the electrolyte ion conduction resistance has temperature dependence. The temperature can be estimated from the operating state (power generation amount, amount of air introduced into the fuel cell, amount of fuel introduced). Thereby, the influence of the temperature dependency of the IR resistance component can be correctly determined.

  In the load disconnection method of the electrochemical system A1 described above, at a required timing, the load separation step of disconnecting the electrochemical device and the external load by the disconnector and the voltage of the electrochemical device when the external load is disconnected are determined. A voltage acquisition step acquired by the voltage detection sensor, a voltage change rate calculation step for calculating a voltage change rate of the electrochemical device when the external load is disconnected based on the acquired voltage value of the electrochemical device, and the calculated voltage Based on the rate of change, it has the content of having a load connection step of connecting an external load to the electrochemical device by a breaker, and its detailed flow is as follows.

FIG. 5 is a detailed flowchart of the load disconnection method of the electrochemical system A1.
First, it is started according to the basic operation control of the electrochemical system A1, and at the same time, the following diagnostic control is executed.
Step 1 (abbreviated as “S1” in the figure. The same applies hereinafter): Supply of fuel and air to the fuel cell 11 is detected.

Step 2: The relay 22 is opened and the open circuit voltage is calculated.
Step 3: The relay 22 is connected, and the power generation state according to the required output of the motor 15 is entered.
Step 4: Judge whether to conduct internal resistance diagnosis. For example, when the operation time recorded in the C / U 30 reaches a preset value, the process proceeds to step 5.
Alternatively, when it is determined that the output is decreasing, the process proceeds to step 5. Specifically, if the measured power generation output is equal to or greater than a certain reduction rate with respect to the power generation output measured in advance corresponding to each fuel and air introduction condition, the process proceeds to step 5.

Step 5: Ascertain the operating state (fuel introduction amount, air introduction amount).
Step 6: The voltage and current of the fuel cell 11 are measured.
Step 7: The relay 22 is opened, and the fuel cell 11 is brought into an open circuit state.
Step 8: Measure the voltage change in the open circuit state.

Step 9: Determine the end of the diagnostic operation.
Specifically, a portion where the voltage change rate does not change in the diagnostic waveform shown in FIG. 3 is determined. A voltage change amount per unit time is calculated, and it is determined that the internal resistance response region due to the IR resistance has ended when this change amount has decreased by a certain value with respect to the change amount immediately after switching. At this time, the rate of decrease of the unit time and the voltage change amount with respect to the initial change amount was set to 0.1 ms and 20%, respectively.

Step 10: Connect the relay 22 to place the fuel cell 11 in the power generation state.
Step 11: Calculate voltage loss due to cross leak, IR resistance and reaction resistance from the information acquired in Steps 2, 5, 6 and 9, respectively.

Step 12: The operating conditions are adjusted according to the obtained internal resistance.
The calculated internal resistance and diagnosis time are stored in the memory 32.

Step 13: Time when deterioration countermeasures such as maintenance are required based on the change tendency of the internal resistance stored in the C / U 30 and a predetermined threshold value (deterioration judgment value) preset for each internal resistance Is calculated. If necessary, a warning display or the like can be output to the system driver.
Step 14: Continue diagnosis and return to Step 3.

  According to the configuration described above, the SOFC has a high operating temperature of approximately 600 ° C. or higher, and in this case, the internal resistance measurement time can be shortened to substantially 1 second or less. This eliminates the need for a special configuration and control (for example, warm-up operation using a burner or the like) for maintaining the operation temperature.

  Next, the electrochemical system which concerns on 2nd embodiment of this invention is demonstrated with reference to FIG. FIG. 6 is a block diagram showing a configuration of an electrochemical system according to the second embodiment of the present invention.

  The electrochemical system A2 according to the second embodiment of the present invention is different from the above-described electrochemical system A1 in that a thermocouple thermocouple 35 for measuring a cell temperature representative of the operation state of the fuel cell 11 is provided. Since they are different, components equivalent to those described in the electrochemical system A1 are denoted by the same reference numerals and description thereof is omitted.

By providing the thermocouple thermocouple 35, the unit time can be changed to a preset value in accordance with the temperature of the fuel cell 11 in step 9 shown in FIG. That is, since the IR loss is reduced when the temperature of the fuel cell 11 is higher, the set time is shortened.
Specifically, a function for adjusting the unit time length based on the temperature of the fuel cell 11. That is, the unit time adjusting means is provided.

  In addition, when performing the calculation of the open circuit voltage E0 [Equations 1 and 2] in Step 10, the thermocouple information acquired by the thermocouple thermocouple 35 is used to improve the diagnosis accuracy of the cross leak amount. be able to. That is, it is possible to calculate a more accurate open circuit voltage by correcting the temperature error estimated according to the operating state with the actual measurement value.

  Next, an electrochemical system according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram showing a configuration of an electrochemical system according to the third embodiment of the present invention.

  In the electrochemical system A3 according to the third embodiment of the present invention, since the accelerator opening sensor 40 is different from the electrochemical system A1 described above, it is equivalent to that described in the electrochemical system A1. About the thing, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

The accelerator opening sensor 40 detects the accelerator opening state of the driver, and is connected to the input port side of the C / U 30.
Also in the present embodiment, processing is performed according to the flowchart shown in FIG. 5 described above. At this time, when the driver determines that the internal resistance diagnosis is to be performed in step 4, the accelerator is off (the foot is released from the accelerator pedal). It is said. Thereby, an internal diagnosis can be implemented without affecting the power generation request.
Further, for example, even if an operation key OFF sensor is provided instead of the accelerator opening sensor and it is detected that the driver has stopped driving, the processing can be performed according to the flowchart shown in FIG. Thereby, an internal diagnosis can be implemented without affecting the power generation request.

  Next, an electrochemical system according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a block diagram showing a configuration of an electrochemical system according to the fourth embodiment of the present invention.

An electrochemical system A4 according to the fourth embodiment of the present invention is a power supply system for an electric vehicle, and has a configuration in which a battery 10A is provided in place of the fuel cell 11 as shown in FIG. is there.
In addition, about the thing equivalent to what was demonstrated in embodiment mentioned above, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

A procedure for diagnosing the internal resistance of the battery 10 will be described with reference to FIG. FIG. 9 is a detailed flowchart of the load disconnecting method of the electrochemical system according to the fourth embodiment of the present invention.
First, it is started according to the basic operation control of the electrochemical system A4, and at the same time, the following diagnostic control is executed.

Step 1 (abbreviated as “S1” in the figure. The same applies hereinafter): The open circuit voltage immediately before the start of system operation is measured.
Step 2: The battery 10A and the motor 15 are connected by the relay 22, and power corresponding to the required output of the motor 15 is supplied.
Step 3: The voltage and current between terminals of the battery 10A are measured.

Step 4: Judge whether to conduct internal resistance diagnosis. For example, when the operation time recorded in the C / U 30 reaches a preset value, the process proceeds to step 5.
In addition, it transfers to step 5 with a fixed voltage or a fixed SOC. Here, the SOC (State of charge) is a value representing the amount of electricity charged as a ratio to the electric capacity.

Step 5: The relay 22 is opened, and the battery 10A is brought into an open circuit state.
Step 6: Measure voltage change in open circuit state.
Step 7: Determine the end of the diagnostic operation.
Specifically, a portion where the voltage change rate in the diagnostic waveform shown in FIG. 3 does not change is determined. A voltage change amount per unit time is calculated, and it is determined that the internal resistance response region due to the IR resistance has ended when this change amount has decreased by a certain value with respect to the change amount immediately after switching. At this time, the rate of decrease of the unit time and the voltage change amount with respect to the initial change amount was set to 0.1 ms and 20%, respectively.

Step 8: Connect the relay 22 and return to the normal operation state.
Step 9: Calculate voltage loss due to IR resistance and reaction resistance from the information acquired in Steps 1, 6 and 7, respectively. Then, the internal resistance is stored in the memory 32.

Step 10: Based on the change tendency of the internal resistance stored in the C / U 30 and a predetermined threshold value (deterioration judgment value) preset for each internal resistance, countermeasures for deterioration such as maintenance and replacement of the battery 10A are performed. Calculate the time when is needed. If necessary, a warning display or the like can be output to the system driver.
The “change tendency of the internal resistance and a predetermined threshold value (degradation judgment value) preset for each internal resistance” are stored in the memory 32 in advance.
That is, a function of calculating a time when it is necessary to cope with the deterioration of the battery 10 </ b> A that is an electrochemical device based on the change tendency of the internal resistance. This function is called “deterioration response time calculation means”.
“Degradation response of battery 10 </ b> A as an electrochemical device” refers to maintenance or replacement of battery 10 </ b> A.
Step 11: Continue diagnosis and return to Step 2.

Next, an electrochemical system according to a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a block diagram showing a configuration of an electrochemical system according to the fifth embodiment of the present invention.
In addition, about the thing equivalent to what was demonstrated in embodiment mentioned above, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

As shown in FIG. 10, an electrochemical system A5 according to the fifth embodiment of the present invention is a battery 10B that employs a secondary battery such as a chargeable / dischargeable lithium ion battery instead of the fuel cell 11 described above. The charging power supply 45 is arranged.
That is, the battery 10 </ b> B can be charged with a direct current supplied from the charging power supply 45.

FIG. 11 is a detailed flowchart of the load disconnecting method of the electrochemical system A5.
First, charging is started according to the basic charging control of this system. At the same time, the diagnostic control of FIG. 11 is executed as follows.
Step 1 (abbreviated as “S1” in the figure, the same applies hereinafter): The open circuit voltage immediately before the start of charging is measured.
Step 2: The relay 22 is connected and power is supplied to the battery 10B.
Step 3: The voltage and current between the terminals of the battery 10B are measured.

Step 4: Determine execution of internal resistance diagnosis of battery 10B. For example, when the charging time recorded in the C / U 30 reaches a preset value, the process proceeds to step 5.
Alternatively, the process may proceed to step 5 with a constant voltage or a constant SOC.

Step 5: The relay 22 is opened, and the battery 10B is brought into an open circuit state.
Step 6: Measure voltage change in open circuit state.
Step 7: Determine the end of the diagnostic operation.
Specifically, a portion where the voltage change rate does not change is determined in the diagnostic waveform shown in FIG. A voltage change amount per unit time is calculated, and it is determined that the internal resistance response region due to the IR resistance has ended when this change amount has decreased by a certain value with respect to the change amount immediately after switching. At this time, the rate of decrease of the unit time and the voltage change amount with respect to the initial change amount was set to 0.1 ms and 20%, respectively.

Step 8: Connect the relay 22 and return to the normal operation state.
Step 9: Calculate voltage loss due to IR resistance and reaction resistance from the information acquired in Steps 1, 6 and 7, respectively. And internal resistance is memorize | stored in C / U30.

Step 10: Deterioration such as maintenance or replacement of the battery 10B based on the change tendency of the internal resistance stored in the C / U 30 and a predetermined threshold (degradation judgment value) preset for each internal resistance. Calculate when action is required. If necessary, a warning display is output to the system operator.
Step 11: Continue diagnosis. Return to step 2.

The present invention is not limited to the above-described embodiments, and the following modifications can be made.
Although described in detail above, in any case, each configuration described in each of the above embodiments is not limited to being applied only to each of the above embodiments, and the configuration described in one embodiment is not limited to other embodiments. It can be applied mutatis mutandis or applied to the form, and can be arbitrarily combined.

10 Electrochemical device 11 Fuel cell 15 Motor (external load)
20 Voltage detection sensor (voltmeter)
22 disconnector 31a load separation means 31b voltage acquisition means 31c voltage change speed calculation means 31d displacement amount determination means 31e load connection means 31f internal resistance calculation means 31g device temperature acquisition means 31h internal resistance correction means S1 device temperature sensor

Claims (8)

An electrochemical system having an electrochemical device, a disconnector for connecting and disconnecting the electrochemical device and an external load, and a voltage detection sensor for detecting the voltage of the electrochemical device,
At a required timing, a load separating means for separating the electrochemical device and the external load by a disconnector;
Voltage acquisition means for acquiring the voltage of the electrochemical device when the external load is disconnected by a voltage detection sensor;
Based on the obtained voltage value of the electrochemical device, voltage change rate calculating means for calculating the voltage change rate of the electrochemical device when the external load is disconnected,
An electrochemical system comprising: a load connecting means for connecting an external load to the electrochemical device by a disconnector based on the calculated voltage change rate. It has a transition amount judging means for judging whether or not the amount of transition of the voltage change speed has become a certain value or more,
2. The electrochemical system according to claim 1, wherein when it is determined that the amount of change in the voltage change rate is equal to or greater than a certain value, the load connection / disconnection means connects an external load to the electrochemical device.   3. The electricity according to claim 1, further comprising an internal resistance calculating unit that calculates an internal resistance of the electrochemical device based on the current change rate, the current-voltage at the time of power generation, or the open-circuit voltage at the time of start-up. Chemical system. A device temperature sensor is provided to detect the temperature of the electrochemical device,
Device temperature acquisition means for acquiring the temperature of the electrochemical device by the device temperature sensor;
The electrochemical system according to any one of claims 1 to 3, further comprising an internal resistance correction unit that increases or decreases the internal resistance value based on the acquired temperature of the electrochemical device.   The electrochemical system according to claim 3, wherein the internal resistance calculation means calculates the internal resistance based on a preset schedule.   The electrochemical system according to claim 3, wherein the internal resistance calculating means calculates the internal resistance in accordance with an external power request signal.   The electrochemical system according to any one of claims 1 to 6, wherein the electrochemical device includes a fuel cell. A load disconnection method for an electrochemical system comprising an electrochemical device, a disconnector for disconnecting the electrochemical device from an external load, and a voltage detection sensor for detecting the voltage of the electrochemical device. There,
At the required timing, a load separation step of separating the electrochemical device and the external load by a disconnector;
A voltage acquisition step of acquiring the voltage of the electrochemical device when the external load is disconnected by a voltage detection sensor;
Based on the obtained voltage value of the electrochemical device, a voltage change rate calculation step for calculating the voltage change rate of the electrochemical device when the external load is disconnected,
And a load connection step of connecting an external load to the electrochemical device by a disconnector based on the calculated voltage change rate.

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