JP5114265B2 - Fuel cell system, backup power supply system and control method thereof - Google Patents

Description

  The present invention relates to a fuel cell system and a backup power supply system that can supply power to a load without causing a power failure when a commercial AC power supply is abnormal, and a control method thereof.

  A polymer electrolyte fuel cell (PEFC) is a device that obtains an electromotive force by electrochemically reacting a fuel gas mainly composed of hydrogen and an oxidant gas. Application to in-vehicle power supply systems is under consideration. Furthermore, as disclosed in Patent Document 1, application to a traffic signal management system is expected.

  Since PEFC can only obtain an electromotive force of about 0.7 to 1.0 V in a single cell, it is generally used in a cell stack structure in which a plurality of single cells are stacked. Inside the cell stack, water is generated by the reaction of hydrogen gas and oxygen gas during power generation, and the generation of water droplets may hinder gas flow and reduce power generation performance. Need to be discharged. As this discharge method, a method is generally used in which the produced water is discharged at a flow velocity that allows the fuel gas to flow through the cell stack. In this case, in order to ensure the gas flow rate, auxiliary equipment such as a pump and a blower is used for both hydrogen gas and oxygen gas, and the PEFC power generation system is provided with a controller for driving the auxiliary equipment.

  Here, it is considered that the PEFC power generation system is applied to a backup power source used in the case of an abnormal power system such as a power failure. The PEFC power generation system consumes standby power when it is not generating power, and requires the starting power of an auxiliary device when starting power generation. For example, in a self-supporting power generation system, there is a method of using a startup battery inside the system. However, for example, when a PEFC power generation system is installed together with an uninterruptible power supply (UPS) that includes a battery such as a communication base station, standby power and start-up power of the PEFC power generation system are obtained from the UPS at the time of a power failure. It can also be supplied.

JP 2006-278174 A

  However, along with the supply of standby power to the PEFC power generation system, there is a problem that the amount of discharge of the battery in the UPS device increases, and the backup time during which the UPS device can back up the load is shortened.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to extend the backup time of a UPS device in a backup power source using both the UPS device and the PEFC system.

  In one aspect of the present invention, an uninterruptible power supply configured to include a power load fed from a commercial power supply, a battery so as to form a backup power supply to the power load, and the uninterruptible power supply A fuel cell system connected to supply generated power to the power load, the fuel cell system comprising: a fuel cell stack; an auxiliary device for assisting the supply of fuel to the fuel cell stack; A power supply unit and a control unit that receives power from the power output unit of the fuel cell system, and supplies and controls the driving power to the auxiliary machine, and monitors the remaining amount of fuel in the fuel cell. When the remaining amount becomes less than a predetermined amount, power consumption in the control device is suppressed.

  In a preferred embodiment of the present invention, the suppression of power consumption in the control device is characterized in that the control device is shifted to a sleep mode.

  Here, the sleep mode is a complete stop state or generally called a power saving mode, a standby mode, etc. `` A state in which only a control circuit unit that operates with weak power maintains judgment and processing capability for external commands and signals. It is assumed that the power circuit section is in a state of not operating.

  In a preferred embodiment of the present invention, the power suppressing means includes means for stopping power supply to the auxiliary machine.

  According to a preferred embodiment of the present invention, it is possible to extend a backup time in a backup power source using both a UPS device and a fuel cell system.

  Other objects and features of the present invention will be clarified in the embodiments described below.

(Embodiment 1)
A first embodiment of a backup power supply system according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing an entire backup power supply system according to Embodiment 1 of the present invention. Normally, power is supplied to the power load 23 from the commercial power supply 20 through the rectifier 21, and this power load 23 is an important facility that requires a backup power source. Therefore, an uninterruptible power supply (UPS) device 22 configured to include a battery so as to form a backup power source for the power load 23 and the uninterruptible power supply device 22 are provided side by side to supply generated power to the power load 23. Thus, the fuel cell system is connected. This fuel cell system is mainly composed of a system main body 14 and a hydrogen storage device 15.

  The rectifier 21 transforms and rectifies the power of the commercial AC power supply 20 when the commercial AC power supply 20 is normal, and supplies a predetermined DC voltage to the load 23. In addition, when the commercial AC power supply 20 is abnormal, power cannot be supplied from the rectifier 21, and thus an uninterruptible power supply system is configured by supplying power from the UPS device 22 to the load 23.

  In general, as the power supplied by the UPS device 22 to the load 23, a method of discharging power previously charged in a secondary battery such as a lead storage battery, a nickel metal hydride battery, or a lithium ion battery is used. In the fuel cell system, the system output terminal 3 provided in the system main body 14 is connected in parallel to the DC output of the rectifier 21 or the UPS device 22 so that the power generated in the system main body 14 can be supplied to the load 23. It is configured.

The system body 14 houses the fuel cell stack 1, the auxiliary machine 2, the DC / DC converter 12, the system output terminal 3, and the control device 4. The fuel cell stack 1 can obtain an electromotive force by a fuel supply operation using the auxiliary machine 2. The electric power generated in the fuel cell stack 1 is converted into DC power whose voltage is controlled according to the voltage command value Vo ^* in the DC / DC converter 12 connected to the fuel cell stack 1, and then supplied to the system output terminal 3. Is done. Here, a rectifier 13 a is connected between the output of the DC / DC converter 12 and the system output terminal 3, and no power flows from the system output terminal 3 to the DC / DC converter 12. The output voltage of the DC / DC converter 12 is a voltage corresponding to DC 24V or DC 48V.

  Although not shown in the drawings, the auxiliary machine 2 pumps, blowers and fans for injecting or circulating hydrogen gas, oxygen gas, refrigerant, etc. to the fuel cell stack 1, electromagnetic valves for opening and closing pipes through which the gas or refrigerant flows, etc. Is included. Here, the hydrogen gas can be obtained from the hydrogen supply pipe 7 supplied from the outside of the system main body 14, while the oxygen gas can be obtained from the air inside the system main body 14. In addition to water and antifreeze for cooling water, cooling air for forced air cooling may be used as the refrigerant.

  The hydrogen storage device 15 is provided outside the system main body 14, and contains a hydrogen cylinder 6, an electromagnetic valve 9, a filling monitoring device 8, and a pressure reducing valve 10, which are connected on the hydrogen supply pipe 7. As the hydrogen cylinder 6, for example, a hydrogen gas cylinder compressed to about 10 megapascals is used. The solenoid valve 9 opens and closes the hydrogen cylinder 6 and the hydrogen supply pipe 7. The filling monitoring device 8 is a device that monitors the filling amount of the hydrogen gas inside the hydrogen cylinder 6. For example, the filling monitoring device 8 monitors the pressure, or monitors the gas flow rate and integrates the time to calculate the difference from the value at the time of replacing the cylinder. The filling amount inside the hydrogen cylinder 6 is estimated by a method such as obtaining. The pressure reducing valve 10 serves to reduce the gas pressure when the allowable pressure of the auxiliary machine 2 and the fuel cell stack 1 is remarkably low, such as 1 to 3 atm, with respect to the filling pressure of the hydrogen cylinder 6. The hydrogen gas decompressed by the pressure reducing valve 10 is connected to the auxiliary machine 2 inside the system main body 14 through the hydrogen supply pipe 7.

  Although a detailed circuit configuration is omitted, devices such as the electromagnetic valve 9 and the filling monitoring device 8 inside the hydrogen storage device 15 are electrically connected to a power terminal 11 provided in the hydrogen storage device 15. 11 can be driven by supplying power from the outside. In addition, the electromagnetic valve 9 is normally closed to close the valve when the power input to the power terminal 11 is lost so that gas does not leak, for example, when a power supply abnormality occurs during the replacement of the hydrogen cylinder 6. It is desirable to use a mold.

The control device 4 is driven using the voltage at the system output terminal 3. Further, the control device 4 monitors the remaining amount Rg of the hydrogen cylinder 6, the external sleep command Se, the state MF of the fuel cell stack 1, etc., while supplying power to the auxiliary machine 2 and transmitting / receiving auxiliary equipment information IA, The voltage command value Vo ^* of the DC / DC converter 12 is output. Further, an external communication connector IF is connected to the control device 4 so that it can communicate with an external device.

  FIG. 2 is a detailed control function block diagram of the control device 4 in FIG.

  The control device 4 includes an auxiliary power source 4A. The auxiliary power source 4A uses the electric power obtained from the system output terminal 3 as a control voltage used in the fuel cell system such as 5V, 12V, and 24V, and the auxiliary machine 2 and the hydrogen storage device. Supply voltage to control 15 etc. The auxiliary power supply 4A is a circuit that controls the output voltage by switching operation of a power semiconductor such as an FET or IGBT, and includes a rectifier circuit such as a diode, a smoothing circuit such as a capacitor and a reactor, and a transformer circuit such as a high-frequency transformer. good. Here, the output power of the auxiliary power source 4A is used as a power source for weak electronic control circuits such as the auxiliary machine 2, the power terminal 11 (FIG. 1) of the hydrogen storage device 15, and the arithmetic unit 4B inside the control device 4. Here, on the power supply line to the power terminal 11 (FIG. 1), since it becomes a wiring to the outside of the system main body 14, a diode 4L for backflow prevention may be provided in preparation for erroneous connection.

The calculation unit 4B includes the following control circuit. That is, first, there is an auxiliary machine control unit 4F that performs control processing related to the nonvolatile memory 4D, the fuel cell stack 1 and the auxiliary machine 2, and a DC / DC control unit 4E that controls the DC / DC converter 12. Next, a gas shortage determination unit 4G that monitors the remaining charge Rg of the hydrogen cylinder 6, a communication unit 4H that communicates with the outside, and a stop control unit 4K that performs a stop operation of the fuel cell stack 1 according to conditions are provided. ing. Here, the auxiliary machine control unit 4F reads information on the voltage and temperature of the internal cells of the fuel cell stack 1 and the sensors included in the auxiliary machine 2, and turns on / off the power supply to the driving equipment included in the auxiliary machine 2. The amount of operation of the device is controlled through analog communication such as OFF control and pump rotation speed. The DC / DC control unit 4E can change the control voltage output from the DC / DC converter 12 to a desired value. The gas shortage determination unit 4G determines the magnitude relationship between the filling remaining amount Rg and the predetermined determination threshold R1, and transmits a stop command S ^* to the stop control unit 4K when Rg is smaller than R1. The stop control unit 4K gives an instruction to the auxiliary machine control unit 4F to stop the power generation operation of the fuel cell stack 1 when either the stop command S * or the external stop command Se is instructed to stop. At the same time, after storing the information of the calculation unit 4B in the nonvolatile memory 4D, a sleep command Sd for shifting the fuel cell system to the sleep mode is transmitted.

  In addition to a complete stop state, the sleep mode is generally called a power saving mode or a standby mode, etc., in which only the control logic unit maintains the ability to judge external commands and signals and does not output power, That is, it includes a standby state in which almost no power is consumed. In this embodiment, the output of the auxiliary power supply 4A is set to zero or the minimum value, and therefore, the auxiliary machine 2 and the control device 4 are turned off and are completely stopped.

  The sleep command Sd is transmitted to the auxiliary power supply 4A via the reset unit 4C. When the sleep command Sd instructs sleep execution, the auxiliary power supply 4A transitions to a state in which the input power of the auxiliary power supply 4A becomes zero or the minimum value. For this purpose, a method of stopping the switching operation of a power semiconductor such as FET or IGBT, reducing the control output voltage to zero, or limiting the output current may be used. Of course, as described above, it is possible to make use of only the electronic control circuit unit that consumes only weak power.

  When the auxiliary power supply 4A is in the sleep state, the reset means 4C monitors the voltage Vo at the system output terminal 3. When the voltage Vo is larger than the predetermined voltage threshold V1 and the external sleep signal Se does not instruct execution of sleep, the sleep command Sd transmitted to the auxiliary power supply 4A is reset, and the auxiliary power supply 4A is changed from the sleep state to the non-sleep state. Therefore, if there is no gas shortage, the auxiliary machine 2 is activated and the PEFC stack 1 resumes power generation. If the gas shortage still remains, the auxiliary machine control unit 4F keeps the contact point 4M open. No power is supplied to 2.

  The fuel cell stack 1 may affect the life of the fuel cell stack 1 if the supply of fuel gas, particularly hydrogen, is insufficient with respect to the amount of power generation. For this reason, when the remaining amount Rg of the hydrogen cylinder 6 falls below the predetermined value R1 during power generation by the fuel cell, it is determined that the power generation of the fuel cell stack 1 cannot be continued and the operation of the fuel cell system is stopped. To do. Here, the predetermined value R1 is preferably set to a level from 1% to 5% of the maximum filling level of the hydrogen cylinder 6.

  Even after the power generation of the fuel cell stack 1 is stopped based on the decrease in the remaining charge Rg, if the commercial AC power supply 20 is abnormal, power is supplied to the load 23 from the UPS device 22.

  At this time, the conventional system main body 14 receives power to the control device 4 through the system output terminal 3, and the UPS device 22 supplies power consumption of the control device 4 including the auxiliary power supply 4A in addition to the load 23. Will do. For this reason, there is a possibility that the backup possible time for the load 23 of the UPS device may be reduced.

  On the other hand, if the auxiliary power supply 4A is set to the sleep state as in the present embodiment, the power consumption of the control device 4 can be reduced to zero or the minimum, and the backup possible time of the UPS device can be prolonged.

  At this time, when the auxiliary power supply 4A enters the sleep state, there is a possibility that the setting state of various parameters of the calculation unit 4B before the sleep transition is lost. Therefore, the parameter setting state can be maintained before and after the sleep transition by storing the parameter of the calculation unit 4B in the nonvolatile memory (EEPROM) 4D based on the instruction of the stop control unit 4K.

  In the reset means 4C, a condition that the voltage Vo is larger than the predetermined voltage threshold value V1 is set as a reset condition in the sleep state. This is provided to determine that the commercial AC power supply 20 has recovered from a power failure. If a power failure and recovery from a power failure are determined outside the fuel cell system, the determination on the threshold value V1 may be ignored, and the sleep state may be managed only by operating the external sleep signal Se.

  According to the above embodiment, the power supply backup time in the fuel cell system and the UPS is cut off from the commercial power supply, and the backup time until the lack of gas by the PEFC power generation + the backup time in the UPS = longer than before. It can be extended as much as possible.

(Embodiment 2)
FIG. 3 is an overall schematic configuration diagram of a backup power supply system according to the second embodiment of the present invention.

  Details of the contents already described in the first embodiment are omitted. FIG. 3 shows a system configuration in which the output terminals 3 and 3 ′ provided on the two system main bodies 14 and 14 ′ are connected in parallel to the load 23. The load 23 is divided into a load 23A and a load 23B. A switch 23C is connected to the load 23B, and all of the system output 3, the rectifier 21, the UPS device 22, and the load 23A are connected to the load 23B. Is configured to be separable. Here, for example, a load such as a communication base station is equipped with a monitoring device, an air conditioner, etc. in addition to the base station main body, and priorities are assigned in the order of the monitoring device, the base station main body, and the air conditioning. Can do. In the relationship between the load 23A and the load 23B, a load having a higher priority is connected to 23A and a load having a lower priority is connected to 23B. The switch 23C is connected to the Sd 'signal on the system body 14' and can be opened and closed by the Sd 'signal.

  The hydrogen supply pipe 7 of the hydrogen storage means 15, the filling remaining amount Rg signal of the hydrogen cylinder 6 and the power terminal are all connected in parallel to the two system bodies 14, 14 '. Further, the communication terminals IF and IF ′ of the two system main bodies 14 and 14 ′ are connected so that they can communicate with each other.

  According to such a configuration, since power can be supplied to the load 23 from the two system outputs 3, 3 ', it is possible to back up more instantaneous power than in the case of one. Here, in the two system main bodies 14 and 14 ′, the thresholds R <b> 1 and R <b> 1 ′ used in the gas shortage determination unit 4 </ b> G are set to a relationship of R <b> 1 ′> R <b> 1. In this way, when the remaining charge Rg signal of the hydrogen cylinder 6 decreases as the fuel cell stack 1 generates power, the system main body 14 'first enters the sleep operation, and the system main body 14 continues to operate. At this time, the switch 23C is opened by operating the Sd 'signal of the system main body 14'. If the power generation of one of the two units is stopped, the consumption per hour of the hydrogen cylinder 6 can be reduced, so that the backup time can be extended and the less important load can be separated by opening the switch 23C. It is possible to further extend the backup time for highly important loads.

1 is a schematic configuration diagram illustrating an entire backup power supply system according to a first embodiment of the present invention. It is a detailed control functional block diagram of the control apparatus 4 in the backup power supply system by Embodiment 1 of this invention. It is a whole schematic block diagram of the backup power supply system by Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack, 2 ... Auxiliary machine, 3 ... System output terminal, 4 ... Control apparatus, 6 ... Hydrogen cylinder, 8 ... Filling monitoring device, Rg ... Remaining filling amount, 14 ... System main body, 15 ... Hydrogen storage device, 20 ... Commercial AC power source, 21 ... Rectifier, 22 ... UPS device, 23 ... Electric power load.

Claims (8)

A power load fed from a commercial power supply, an uninterruptible power supply configured to include a battery so as to form a backup power supply to the power load, and an electric power generated by the uninterruptible power supply attached to the power load A fuel cell system for connecting to supply
A fuel cell stack, an auxiliary device for assisting the supply of fuel to the fuel cell stack, the uninterruptible power supply and the power output unit of the fuel cell system, receiving power from the power supply unit, supplying driving power to the auxiliary device, and In a fuel cell system provided with a control device responsible for the control,
Fuel remaining amount monitoring means for monitoring the fuel remaining amount of the fuel cell, and when the fuel remaining amount becomes less than a predetermined amount, the control device is shifted to a sleep mode to suppress power consumption in the control device. Having power suppression means ,
The control device includes a non-volatile memory, and includes means for recording parameters of the control device in the non-volatile memory prior to power suppression by the power suppression unit when the fuel in the fuel cell becomes less than a predetermined amount. fuel cell system, characterized by that. Oite to claim 1, wherein the power suppression means, the fuel cell system characterized by comprising a means for stopping power supply to the auxiliary machine. 3. The power supply device according to claim 1, further comprising an auxiliary power supply device that takes power into the control device from the uninterruptible power supply device and the power output unit of the fuel cell system, wherein the power suppression unit is configured to receive power that the auxiliary power device takes A fuel cell system comprising means for suppressing the value below a predetermined value. In any one of claims 1 to 3, is connected to a commercial AC power source, comprising a rectifier for supplying DC power to the power output of the uninterruptible power supply to the fuel cell system, the power suppression means, the commercial A fuel cell system configured to suppress power consumption in the control device when an AC power supply is in a power failure state and fuel in the fuel cell becomes less than a predetermined amount. In any one of claims 1 to 3, is connected to a commercial AC power source, comprising a rectifier for supplying DC power to the power output of the uninterruptible power supply to the fuel cell system, the power suppression means, the commercial When the AC power supply is in a power outage state and the fuel in the fuel cell is less than a predetermined amount, the power consumption in the control device is suppressed, and in this power suppression state, when the commercial AC power supply is restored, A fuel cell system configured to release the power suppression. A power load fed from a commercial power supply, an uninterruptible power supply configured to include a battery so as to form a backup power supply to the power load, and an electric power generated by the uninterruptible power supply attached to the power load A fuel cell system connected to supply
The fuel cell system receives power from a fuel cell stack, an auxiliary device that assists the supply of fuel to the fuel cell stack, the uninterruptible power supply and the power output unit of the fuel cell system, and supplies the auxiliary device to the auxiliary device. In a backup power supply system equipped with a control device for supplying and controlling the driving power of
Fuel remaining amount monitoring means for monitoring the fuel remaining amount of the fuel cell, and when the fuel remaining amount becomes less than a predetermined amount, the control device is shifted to a sleep mode to suppress power consumption in the control device. Having power suppression means ,
The control device includes a non-volatile memory, and includes means for recording parameters of the control device in the non-volatile memory prior to power suppression by the power suppression unit when the fuel in the fuel cell becomes less than a predetermined amount. backup power system, characterized by that. The switch according to claim 6 , wherein the uninterruptible power supply and the plurality of power loads connected in parallel to the power output unit of the fuel cell system, and the switch capable of disconnecting at least one of these power loads from the power output unit. And a means for opening the switch in conjunction with the operation of the power suppression means. A power load fed from a commercial power supply, an uninterruptible power supply configured to include a battery so as to form a backup power supply to the power load, and an electric power generated by the uninterruptible power supply attached to the power load A fuel cell system connected to supply
The fuel cell system receives power from a fuel cell stack, an auxiliary device that assists the supply of fuel to the fuel cell stack, the uninterruptible power supply and the power output unit of the fuel cell system, and supplies the auxiliary device to the auxiliary device. In a control method of a backup power supply system provided with a control device for supplying and controlling the driving power of
A fuel remaining amount monitoring step for monitoring the remaining amount of fuel in the fuel cell, and when the remaining fuel amount becomes less than a predetermined amount, the control device is shifted to a sleep mode to suppress power consumption in the control device. A backup power supply comprising: a power suppression step; and a step of recording a parameter of the control device in a non-volatile memory prior to the power suppression step when the fuel in the fuel cell becomes less than a predetermined amount How to control the system.

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