JP2010040305A - Fuel cell power generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generating device improved in overall efficiency. <P>SOLUTION: The fuel cell power generating device has a power supply block 106 that has a small capacity power supply 116 and a large capacity power supply 117. The small capacity power supply 116 has a small capacity AC/DC converter 118 and a small capacity switching means 120. The large capacity power supply 117 has a large capacity AC/DC converter 122 which converts a commercial AC 103 into a third prescribed voltage, and a large capacity switching means 123 which outputs a third prescribed voltage when the power generation block 105 is started and finished, and outputs the output voltage of a stack 107 to a large capacity power equipment in the power generation block 105 upon power generation, and does not output to the large capacity power equipment in the power generation block 105 when shut down. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply configuration of a fuel cell power generator.

  Conventionally, in order to improve the overall efficiency, this type of fuel cell power generator includes a DC output power of the fuel cell that is only DC voltage converted and supplied to an auxiliary machine during power generation (see, for example, Patent Document 1). .

  FIG. 10 is a block diagram of the conventional fuel cell power generator.

  As shown in FIG. 10, the fuel cell power generator 1 is connected to a commercial AC 3 via a distribution board 2 installed in the home. Further, a home load 4 such as an air conditioner or a refrigerator is connected between the distribution board 2 and the fuel cell power generator 1.

  The fuel cell power generator 1 also includes a fuel cell 5 that generates power using fuel gas and oxidant gas, an inverter 6 that converts the output of the fuel cell 5 from direct current to alternating current, and activation of the fuel cell power generator 1. A control means 7 for controlling a series of operations of power generation, termination and stop, a reformer 8 for steam reforming a raw material such as city gas to generate a fuel gas mainly composed of hydrogen, and an oxidant gas. A blower 9 for supplying air to the fuel cell 5 and a hot water storage tank 10 that collects heat generated when the fuel cell 5 generates power and stores it as hot water.

In addition, the reformer 8 and the hot water storage tank 10 are provided with a valve 11 for supplying / shutting off gas and water through piping, and an auxiliary device 11 such as a pump. The power source for driving the auxiliary machine 11 is supplied by converting the output of the fuel cell 5 into a DC voltage by the DC / DC converter 12. Therefore, when the power is generated, it is possible to reduce the conversion loss by directly converting the DC / DC converter 12 to DC voltage and supplying it to the auxiliary machine 11 after DC / AC conversion via the inverter 6. The overall efficiency of the fuel cell power generator 1 can be improved.
JP 2003-197234 A

  In addition to power generation, the fuel cell power generator 1 has operating states such as start, end, and stop. The start-up is an operation that causes the reformer 8 to stably generate the fuel gas, and the end of the operation is to stop the generation of the fuel gas in the reformer 8, and the fuel cell 5 does not generate power. This is an operation to keep it stably in a possible state, and each takes about 1 hour.

  In addition, the fuel cell power generation device 1 cannot always be in a power generation state because the capacity of the hot water storage tank 10 that stores heat generated during power generation is limited and the use state of the user's hot water is not constant. .

  For example, in summer when the amount of hot water used is small, there are many days when power can be generated only for 5 to 6 hours. In this case, power is supplied from the commercial AC 3 to the auxiliary machine 11 via an AC / DC converter (not shown) during the start-up, end, and stop times that are non-power generation.

  That is, the conventional configuration has a problem that the overall efficiency of the fuel cell power generation device 1 cannot be improved with respect to three states of start, end, and stop that occupy half or more of the operation time.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to improve the overall efficiency of a fuel cell power generator.

  In order to achieve this object, the present invention includes a power generation block, a power supply block that supplies power to the power generation block, and a control unit that performs operation control of the power generation block and the power supply block. A hydrogen generator that generates a fuel gas mainly composed of hydrogen from a hydrocarbon-based raw material gas and water, a stack that generates electricity by reacting the fuel gas and oxidant gas from the hydrogen generator, and An inverter that converts the direct current power into alternating current power, wherein the power supply block includes a small capacity power source that supplies power to the control means and a small capacity power device in the power generation block, and a large capacity in the power generation block. A small capacity AC / DC converter that converts commercial alternating current into a first predetermined voltage, and the stack. A small-capacity DC / DC converter that converts the output to a second predetermined voltage, and a small-capacity that consumes predetermined power on the low-side of the output voltage of the small-capacity AC / DC converter and the small-capacity DC / DC converter When the power consumption block is activated, terminated and stopped, the first predetermined voltage is output to the small-capacity power device of the power generation block, and the second predetermined voltage is A small-capacity switching unit that outputs to the small-capacity power device of the power generation block, the large-capacity power source includes a large-capacity AC / DC converter that converts the commercial alternating current into a third predetermined voltage, and the power generation block includes The third predetermined voltage is output to the large-capacity power device of the power generation block when starting and ending, and the output of the stack is output to the power generation block when generating power The output to the high-capacity power apparatus, when it is stopped, is characterized in that it has a large capacity switching means for stopping the output to the high-capacity power apparatus of the power block.

  Thereby, the said objective can be achieved.

  That is, according to the present invention, it is possible to supply operating power using only a small-capacity power source when stopping, and using a small-capacity power source and a large-capacity power source when starting, generating, and ending. In addition, the small capacity power source and the large capacity power source can supply the operation power source using the DC power generated by the stack as the supply source during power generation. Further, even when switching the power supply source, stable supply can be continued without interrupting the power supply to the control means.

  As a result, it is possible to improve the overall efficiency while ensuring the stable operation of the fuel cell power generator.

  The fuel cell power generator according to the present invention supplies power to a small-capacity power device of a power generation block using only a small-capacity power supply when the required power is low, and has a small capacity when starting, generating, and ending the required power. Since power for operation is supplied to the small-capacity power equipment and large-capacity power equipment of the power generation block using the power source and the large-capacity power supply, the power efficiency of the small-capacity power supply and the large-capacity power supply can be optimized according to the capacity. As a result, the overall efficiency of the fuel cell power generator can be improved.

  In addition, the small-capacity power supply and the large-capacity power supply supply operating power from the DC power generated by the stack during power generation, so the loss during power conversion is reduced compared to the DC / AC conversion of the stack generated power. This also makes it possible to improve the overall efficiency of the fuel cell power generator.

  Further, even when the output of the small-capacity AC / DC converter and the small-capacity DC / DC converter is switched by the small-capacity switching means, the converter that is not outputting always consumes power by the small-capacity power consuming means and maintains the output ready state. Therefore, even when switching between the power supply sources of commercial alternating current and stack, stable operation of the fuel cell power generator can be realized without interrupting the power supply from the small capacity power source to the control means.

  The first invention includes a power generation block, a power supply block for supplying power to the power generation block, and a control means for controlling the operation of the power generation block and the power supply block. The power generation block is composed of hydrocarbon-based source gas and water. A hydrogen generator that generates fuel gas mainly composed of hydrogen, a stack that generates electricity by reacting the fuel gas and oxidant gas from the hydrogen generator, and DC power from this stack is converted to AC power The power supply block includes a control means, a small capacity power source that supplies power to the small capacity power device in the power generation block, and a large capacity power source that supplies power to the large capacity power device in the power generation block. The small-capacity power supply includes a small-capacity AC / DC converter that converts commercial alternating current into a first predetermined voltage, and a small-capacity DC / DC converter that converts output from the stack into a second predetermined voltage. Data, a small capacity AC / DC converter, a small capacity power consumption means for consuming predetermined power to the low output voltage side of the small capacity DC / DC converter, and when the power generation block is started, terminated and stopped A small-capacity switching unit that outputs a first predetermined voltage to the small-capacity power device of the power generation block and outputs a second predetermined voltage to the small-capacity power device of the power generation block when generating power; Is a large-capacity AC / DC converter that converts commercial alternating current to a third predetermined voltage, and outputs a third predetermined voltage to the large-capacity power device of the power generation block when the power generation block is activated and terminated. The stack output is output to the large-capacity power device of the power generation block when the power is being stopped, and the large-capacity switching means for stopping the output of the power generation block to the large-capacity power device when the power is stopped. It is obtained by a configuration in which.

  In other words, according to the present invention, the fuel cell power generation device of the present invention supplies power to the control means and the small-capacity power equipment of the power generation block using only a small-capacity power supply when the necessary power is low, and the necessary power is When large start-up, power generation, and termination, the small-capacity power supply and the large-capacity power supply are used to supply operating power to the small-capacity power equipment and the large-capacity power equipment of the power generation block. It can be optimized according to the capacity, and as a result, the overall efficiency of the fuel cell power generator can be improved.

  In addition, the small-capacity power supply and the large-capacity power supply supply operating power from the DC power generated by the stack during power generation, so the loss during power conversion is reduced compared to the DC / AC conversion of the stack generated power. This also makes it possible to improve the overall efficiency of the fuel cell power generator.

  Further, the output capacity of the small-capacity AC / DC converter and the small-capacity DC / DC converter, which has a lower output voltage, is always maintained by the power consumption by the small-capacity power consuming means. Even when switching the power supply source of the stack, the stable supply is continued without being interrupted by the power supply from the small capacity power supply to the control means, and as a result, the stable operation of the fuel cell power generator can be realized.

  In the second invention, in particular, the large-capacity power supply of the first invention has a large-capacity DC / DC converter that converts the output of the large-capacity switching means into a fourth predetermined voltage. Since the voltage can be stably maintained at a predetermined voltage, the conditions for the input voltage range of a large-capacity power device (eg, a valve, a pump, etc.) operating with a large-capacity power supply as an operating power supply are relaxed. As a result, this large-capacity power Selection of equipment (for example, a valve, a pump, etc.) becomes easy, and the cost of the fuel cell power generator can be reduced.

  In the third invention, since at least one of the small-capacity switching means and the large-capacity switching means of the first or second invention is constituted by a semiconductor element, a small-capacity AC / DC converter and a small-capacity DC / DC converter are provided. The output of each other, or the mutual output of the large-capacity AC / DC converter and the stack can be prevented from flowing back. As a result, these small-capacity AC / DC converter, small-capacity DC / DC converter, large-capacity AC / DC Damage and deterioration of the DC converter and the stack can be prevented.

  In the fourth aspect of the invention, in particular, the small-capacity power supply of the third aspect of the invention is configured such that the first predetermined voltage is lower than the second predetermined voltage, and the small-capacity switching means is configured by a diode OR circuit. When the power is generated and the stack output voltage rises and the small-capacity DC / DC converter operates, the small-capacity switching means operates so that the second predetermined voltage is automatically output, and the power source is commercialized. The operation of switching between alternating current and stack can be performed stably and automatically without interruption of the power source.

  Since the fifth invention is provided with a switch for turning on / off the small-capacity power consumption means of any one of the first to fourth inventions in particular, the small-capacity power consumption means can be turned off when unnecessary. Unnecessary power consumption in the low power consumption means can be suppressed, and the overall efficiency of the fuel cell power generator can be improved.

  In the sixth aspect of the invention, in particular, since the switch of the fifth aspect of the invention is turned on for a certain period before the switching timing of the first predetermined voltage and the second predetermined voltage, the small capacity AC / DC converter and the small capacity DC / DC converter Since the power consumed by the small-capacity power consuming means is minimized to prepare for output, the overall efficiency of the fuel cell power generator can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a fuel cell power generator according to a first embodiment of the present invention.

  As shown in FIG. 1, the fuel cell power generator 101 is connected to a commercial AC 103 via a distribution board 102 installed in the home. Further, a home load 104 such as an air conditioner or a refrigerator is connected between the distribution board 102 and the fuel cell power generator 101.

  The fuel cell power generation apparatus 101 includes a power generation block 105 that performs an actual power generation operation and a power supply block 106 that supplies power for operating the power generation block 105.

  The power generation block 105 includes a stack 107 that generates power using fuel gas and an oxidant gas, an inverter 108 that converts output DC power of the stack 107 into AC power, and a fuel cell power generation apparatus 101 (that is, the power generation block 105). The power supply block 106) that supplies power for operating the power generation block 105) is controlled by a control means 109 for controlling a series of operations of starting, power generation, termination, and stop, and steam reforming raw material such as city gas is mainly used for hydrogen. A hydrogen generator 110 that generates fuel gas as a component, a blower 111 for supplying air as an oxidant gas to the stack 107, and a heat storage tank that collects heat generated when the stack 107 generates power and stores it as hot water 112 includes waste heat recovery means 113 stored in 112.

  In addition, the hydrogen generator 110, the blower 111, and the waste heat recovery means 113 include a valve that switches the flow path of gas and water, an actuator 114 such as a heater that raises the temperature of the hydrogen generator, and a flow path of gas and water. The sensor 115 is configured to measure temperature, flow rate, and the like.

  The power supply block 106 includes two independent power sources, a small capacity power source 116 and a large capacity power source 117. Both the small-capacity power supply 116 and the large-capacity power supply 117 are configured to generate a DC voltage with the commercial AC 103 and the stack 107 as inputs, and to supply power to the power generation block 105 while arbitrarily switching the inputs.

  The small-capacity power supply 116 converts the commercial AC 103 input to the fuel cell power generation apparatus 101 into a predetermined DC voltage by the small-capacity AC / DC converter 118 and inputs it to the small-capacity switching means 120. The output voltage 107 is converted into a predetermined DC voltage by the small capacity DC / DC converter 119 and input to the small capacity switching means 120.

  Here, the small capacity switching means 120 is composed of a diode OR circuit, and generates power while selectively switching the higher one of the voltages inputted from the small capacity AC / DC converter 118 and the small capacity DC / DC converter 119. Power is supplied to the block 105.

  In addition, the small-capacity power supply 116 has several types of sensors such as a gas leak detection sensor for monitoring the state of the control means 109 in the power generation block 105 and the fuel cell power generation apparatus 101 (several types of sensors such as these gas leak detection sensors are installed in this embodiment. In the embodiment, it is a power source necessary for operating a small capacity power device), and is preferably configured with a relatively small power source capacity.

  In this embodiment, the small-capacity power supply 116 has a power supply capacity of 10 W, an output voltage of the small-capacity AC / DC converter 118 is 12 V, and an output voltage of the small-capacity DC / DC converter 119 is 14 V.

  A small capacity power consuming means 121 is also connected to the output stage of the small capacity AC / DC converter 118. Here, in general converter operation, even when the input voltage and current are sufficient, if the load on the output side fluctuates suddenly, it cannot respond to the fluctuation, and the output voltage may become unstable. . In particular, when the output-side load suddenly rises from 0, the output voltage may drop to almost 0.

  In order to solve this problem, it is necessary to apply a very small amount of load without completely setting the output load of the converter to zero. Therefore, a small-capacity power consumption means 121 is connected to the output stage of the small-capacity AC / DC converter 118 in order to give a load necessary to maintain the output preparation state. The size of the load needs to be determined according to the characteristics of the small capacity AC / DC converter 118, but is preferably as small as possible from the viewpoint of power consumption. In the present embodiment, the small-capacity power consuming means is constituted by a 1 kΩ resistor and has a power consumption of 12 mW.

  Next, the configuration of the large capacity power source 117 will be described.

  The commercial AC 103 is input to the large-capacity AC / DC converter 122, converted into a predetermined DC voltage, and then input to the large-capacity switching means 123. The large capacity switching means 123 is configured so that the output voltage of the stack 107 is directly input.

  Here, the large capacity switching means 123 is constituted by a diode OR circuit, and the large capacity DC / DC while selectively switching the higher one of the voltages inputted from the large capacity AC / DC converter 122 and the stack 107. Power is supplied to the power generation block 105 via the converter 124.

  The large-capacity power source 117 is a driving power source for the actuator 114 and the sensor 115 in the power generation block 105 (the actuator 114 and the sensor 115 are referred to as a large-capacity power device in this embodiment). Larger power supply is required. Further, as the power supply voltage of the actuator 114 and the sensor 115, voltages such as 12V and 24V are generally used. Therefore, in this embodiment, the power capacity of the large capacity power supply 117 is 100 W, the output voltage of the large capacity AC / DC converter 122 is 15 V, and the output voltage of the large capacity DC / DC converter 124 is 24 V.

  The operation and action of the fuel cell power generation apparatus 101 configured as described above will be described below.

  The operation of the fuel cell power generation apparatus 101 can be broadly divided into four control states such as startup, power generation, termination, and stop.

  Activation is a step of making the power generation block 105 in a state where power generation is possible, and power generation is a state in which power is output from the stack 107.

  The end is a step of making the power generation block 105 in a state in which power generation is impossible, and the stop is a state in which the next power generation instruction is awaited while monitoring the state of the fuel cell power generation device 101.

  The fuel cell power generation apparatus 101 appropriately performs a power generation operation while transitioning the above-described four control states at a timing programmed in advance. Here, if the learning function is such that the programmed timing is appropriately updated according to the usage situation of the user's home load 104, the time zone frequently used by the user is predicted in advance. Since the control state is shifted so that power generation is performed only during that time period, it is preferable because power generation can be performed more efficiently. Further, the transition timing may be an operation by the user.

  First, activation will be described.

  In order for the power generation block 105 to be able to generate power, a preparation operation such as the generation of fuel gas is required. For example, the operation is to generate a fuel gas mainly composed of hydrogen from a raw material such as city gas. Specifically, feedback control is performed on the actuator 114 such as a heater or a fan while taking the measured values of the temperature sensor and the flow rate sensor that are attached to the hydrogen generator 110, and the temperature of the hydrogen generator 110 is controlled. The temperature is raised to about 600 to 700 degrees, and the city gas is steam reformed to generate fuel gas.

  When the startup process is sufficiently advanced and fuel gas is stably generated, the power generation by the stack 107 is started. The stack 107 is formed by stacking a plurality of cells each including an anode electrode and a cathode electrode with an electrolyte membrane interposed therebetween. By supplying fuel gas to the anode electrode side and air as an oxidant to the cathode electrode side, the stack 107 generates power by a chemical reaction.

  The DC power output from the stack 107 is converted into AC power by the inverter 108 and supplied to the household load 104. In addition, a cooling water circulation path connected to the waste heat recovery means 113 is configured in the stack 107. The actuator 114 such as a pump provided with the waste heat recovery means 113 is controlled to recover heat generated during the chemical reaction by heat exchange, and is stored in the hot water storage tank 112 as hot water.

  Next, the end will be described.

  The supply of the city gas is shut off by closing the valve, and the fuel gas generation in the hydrogen generator 110 is stopped. Then, the fan provided in the hydrogen generator 110 is driven to cool the hydrogen generator 110 to a temperature at which the city gas is not reformed. In order to prevent the power generation block 105 from being deteriorated, the stack 107, the hydrogen generator 110, the gas path, and the like are purged with an inert gas.

  When the end process is sufficiently performed and the power generation block 105 is stably maintained in a state where power generation is not possible, the operation of the actuator 114 is stopped to prepare for the next power generation timing. Even during this stoppage, the safety state of the fuel cell power generation apparatus 101 is monitored by a gas leak detection sensor or the like, and when an abnormality occurs, a predetermined abnormality process is performed such as notifying the user.

  In addition, in the three states of starting, ending, and stopping excluding power generation, the AC power is not output from the fuel cell power generation apparatus 101, so the power of the household load 104 is supplied from the commercial AC 103 and operates.

  Regarding the fuel cell power generation apparatus 101 that operates as described above, the detailed operation and action of the power supply from the power supply block 106 to the power generation block 105 will be described.

  When the fuel cell power generation apparatus 101 is installed, commercial AC 103 is input to the power supply block 106 of the fuel cell power generation apparatus 101 via the distribution board 102.

  The commercial AC 103 input to the small-capacity power supply 116 is converted into a DC voltage 12 V by the small-capacity AC / DC converter 118 and supplied to the power generation block 105 via the small-capacity switching means 120. When the DC voltage 12V is supplied, the control means 109 starts to operate and controls the fuel cell power generator 101 according to the four states described above.

  Hereinafter, the operation of the power supply block 106 for each state will be described with reference to FIGS. FIG. 2 is an operation flowchart of the small capacity power supply 116, and FIG. 3 is an operation flowchart of the large capacity power supply 117.

  First, the operation of the small-capacity power supply 116 when stopped will be described.

  If it is determined that the commercial AC 103 has been input (S101), the commercial AC 103 is converted to a DC voltage of 12V by the small capacity AC / DC converter 118 (S102) and input to the small capacity switching means 120.

  If the commercial AC 103 is not input (S101), the small capacity AC / DC converter 118 is stopped (S103).

  Further, since no power generation is performed, there is no output from the stack 107, and the small capacity DC / DC converter 119 does not operate (S107). As a result, the relationship of “the output voltage (12 V) of the small capacity AC / DC converter> the output voltage (0 V) of the small capacity DC / DC converter” is established with respect to the input of the small capacity switching means 120.

  Since the small capacity switching means 120 supplies the higher one of the two input voltages to the power generation block 105, the DC voltage 12V is supplied to the power generation block 105 from the small capacity AC / DC converter 118 using the commercial AC 103 as the supply source. (S108, S109).

  Here, since the small-capacity switching means 120 has a configuration in which two inputs are joined by an OR circuit using a diode, the power source can be supplied by automatically switching the input source if the level of the input voltage changes.

  At this time, the diode prevents the current from flowing from the output of the small-capacity AC / DC converter 118 having a high voltage to the output of the small-capacity DC / DC converter 119 having a low voltage. Here, the small-capacity AC / DC converter 118 also supplies power to the small-capacity power consumption means 121 (S104).

  Similarly, when it is determined that the commercial AC 103 is input to the large-capacity power supply 117 at the time of stopping (S201), the commercial AC 103 is converted into a DC voltage of 15 V by the large-capacity AC / DC converter 122 (S202), and the large-capacity switching is performed. Input to means 123.

    When the commercial AC 103 is not input (S201), the large-capacity AC / DC converter 122 is stopped (S203).

  Further, since no power generation is performed, there is no output from the stack 107. As a result, the output of the large capacity AC / DC converter 122 (15V)> the output voltage of the stack 107 with respect to the input of the large capacity switching means 123. (0V) "is established.

  Here, the large-capacity switching means 123 is also configured to merge with the OR or color of the two input diodes similarly to the small-capacity switching means 120, so that the input source is automatically switched according to the input voltage level and the output voltage is high. As a result, the output voltage of the large-capacity AC / DC converter 122 is supplied to the power generation block 105 via the large-capacity DC / DC converter 124 using the commercial AC 103 as a supply source. Is supplied as a DC voltage of 24 V (S204, S205).

  If the relationship “output voltage of large-capacity AC / DC converter 122 ≦ output voltage of stack 107” is established during power generation (S204), the output voltage of stack 107 is generated via large-capacity DC / DC converter 124. It supplies to the block 105 (S206).

  Next, the operation of the small-capacity power supply 116 at startup will be described.

  Since there is no input from the stack 107 as in the case of the stop, the DC output voltage 12V of the small capacity AC / DC converter 118 is continuously supplied to the power generation block 105 and the small capacity power consumption means 121 (S104, S109).

  Similarly, since there is no input from the stack 107, the large-capacity power supply 117 at the time of start-up continues the DC output voltage of the large-capacity AC / DC converter 122 as a DC voltage 24V via the large-capacity DC / DC converter 124 to the power generation block 105. The supply continues (S205).

  Next, the operation of the small capacity power supply 116 during power generation will be described.

  When power generation is performed and the output voltage from the stack 107 rises and exceeds 13 V, which is the operable lower limit voltage of the small-capacity DC / DC converter 119 (S105), the small-capacity DC / DC converter 119 operates and the DC voltage 14V is output (S106).

  Then, the small-capacity switching means 120 uses the output voltage of the stack 107 as the supply source from the relationship “output voltage (12V) of the small-capacity AC / DC converter 118 <output voltage (14V) of the small-capacity DC / DC converter 119”. Then, the operation is switched so as to supply the DC voltage 14V to the power generation block 105 (S108, S110). However, the power supply from the small capacity AC / DC converter 118 to the small capacity power consumption means 121 is continued (S104).

  On the other hand, when the output voltage of the stack 107 rises and exceeds 15V, the large-capacity power supply 117 during power generation indicates that “the output voltage of the large-capacity AC / DC converter 122 (15V) <the output voltage of the stack 107 (15V or more)”. Therefore, the large-capacity switching means 123 configured by the diode OR circuit automatically supplies the output voltage of the stack 107 as the DC voltage 24V to the power generation block 105 via the large-capacity DC / DC converter 124. The operation is switched as described above (S204, S206).

  Next, the operation of the small capacity power supply 116 at the end will be described.

  When the power generation is stopped and the output voltage of the stack 107 is gradually decreased to fall below the operable lower limit voltage 13V of the small capacity DC / DC converter 119 (S105), the small capacity DC / DC converter 119 is stopped (S107). Then, the small-capacity switching means 120 uses the commercial AC 103 as the supply source in accordance with the relationship “output voltage (12V) of the small-capacity AC / DC converter 118> output voltage (0V) of the small-capacity DC / DC converter 119”. The operation is automatically switched so as to supply the voltage 12V to the power generation block 105.

  At this time, the output load rapidly increases with respect to the small capacity AC / DC converter 118. However, since the small-capacity AC / DC converter 118 continues to supply 12 mW of power to the small-capacity power consumption means 121 even during power generation, the power output can be maintained even when the output load suddenly increases. Thus, stable power supply can be continued without reducing the output voltage even during automatic switching.

  On the other hand, when the output voltage of the stack 107 becomes 15V or less, the large-capacity power supply 117 at the end of the high-capacity switching means 123 causes the "high-capacity AC / DC converter 122 output voltage (15V)> stack 107 output voltage (15V Therefore, the DC voltage 24V is automatically supplied to the power generation block 105 via the large-capacity AC / DC converter 122 and the large-capacity DC / DC converter 124 with the commercial AC 103 as the supply source. The operation is switched (S204, S205).

  Here, when the large-capacity switching means 123 is automatically switched, the load on the output side of the large-capacity AC / DC converter 122 increases abruptly, so that a voltage drop occurs as in the small-capacity AC / DC converter 118. Is concerned. However, since the output of the stack 107 is not cut off and gradually decreases, even if the output voltage of the large-capacity AC / DC converter 122 decreases, it automatically goes to the stack 107 side again when it is slightly below 15V. The power supply to the power generation block 105 is continued.

  The power supply of the power supply block 106 in each of the above states is summarized from the viewpoint of what power is required in the power generation block 105 and the source of the power supplied from the power supply block 106 (Table 1). is there.

  For each of the four states of the fuel cell power generation device, the power required for the power generation block 105 at that time, the power supply block 106, which of the small-capacity power supply 116 and the large-capacity power supply 117 supplies power, and It indicates whether the supply source is the commercial AC 103 or the stack 107, and the operating converter is an AC / DC converter or a DC / DC converter.

  According to Table 1, only the small-capacity power supply 116 supplies power in a stop state where the required power is as low as 10 W. Although the large-capacity power supply 117 is operating, since the actuator 114 is stopped, the power supply is substantially the same as when the power supply is stopped.

  FIG. 4 is a characteristic diagram showing power supply efficiency characteristics of the small capacity AC / DC converter 118. As shown in FIG. 4, since the power supply efficiency is designed to be improved with 10 W that is actually necessary power, the power consumed by the fuel cell power generation apparatus 101 in the stopped state can be reduced. Specifically, since the power efficiency at 10 W is 80%, the power actually consumed from the commercial AC 103 is 12.5 W (= 10 W ÷ 80%).

  Here, the effect is shown compared with the case where power is supplied by one AC / DC converter for the four states of the fuel cell power generation apparatus 101 (conventional example).

  In order to supply power to the four states, it is necessary to design the power source in accordance with the maximum power among the four states. For this purpose, a large capacity AC / DC converter 122 must be used.

  FIG. 5 is a characteristic diagram showing the power supply efficiency characteristics of the large-capacity AC / DC converter 122. The power supply efficiency at the time of 10W output is about 65% because the efficiency is improved with the required power of 100W at the start and end. It is low. Accordingly, the power consumption is 15.4 W (= 10 W ÷ 65%). Therefore, according to the configuration of the present embodiment, compared with the case where the large-capacity AC / DC converter 122 supplies power to the four states, the power consumption is 2.9 W (= 15.4 W-12.5 W) when stopped. Power consumption can be reduced, and the overall efficiency of the fuel cell power generation apparatus 101 can be improved.

  Further, from Table 1, since both the small-capacity power supply 116 and the large-capacity power supply 117 operate using the DC power generated by the stack 107 instead of the commercial AC 103 during power generation, the DC power of the stack 107 is converted into an inverter. The fuel cell power generation apparatus 101 can be operated more efficiently than the case where the AC is converted into AC at 108 and supplied to the commercial AC 103, and the power supplied as the commercial AC 103 is converted by the AC / DC converter. .

  This will be specifically described below with reference to FIGS.

  6 is a characteristic diagram showing the power supply efficiency characteristic of the small-capacity DC / DC converter 119, and FIG. 7 is a characteristic chart showing the power supply efficiency characteristic of the large-capacity DC / DC converter 124.

  For the small-capacity power supply 116, since the power efficiency of the small-capacity DC / DC converter 119 is 85% at 10 W as shown in FIG. 6, the actual power consumed by the stack 107 is 11.8 W (= 10 W ÷ 85%). .

  For the large capacity power source 117, the direct current output of the stack 107 is supplied only through the large capacity DC / DC converter 124. From FIG. 7, since the power supply efficiency of the large capacity DC / DC converter 124 is 85% at 100 W, the power consumed from the stack 107 is 117.6 W (= 100 W ÷ 85%). As a result, the power consumption of the power supply block 106 is 129.4 W (= 11.8 W + 117.6 W) in total.

  On the other hand, when AC conversion by the inverter 108 and conversion by the AC / DC converter are performed, if the conversion efficiency of the inverter 108 is 90%, the small-capacity power supply 116 is smaller than that shown in FIG. Therefore, 13.9 W (= 10 W ÷ 90% ÷ 80%) is the power consumption in the stack 107.

  Similarly, for the large-capacity power supply 117, since the power efficiency of the large-capacity AC / DC converter 122 is 80% at 100 W from FIG. 5, 138.9 W (= 100 W ÷ 90% ÷ 80%) is consumed in the stack. The total power consumption of the power supply block 106 is 152.8 W (= 13.9 W + 138.9 W).

  Therefore, according to the configuration of the present embodiment, the generated power of the stack 107 is converted into alternating current by the inverter 108 and supplied to the commercial alternating current 103, and compared with the case where the commercial alternating current 103 is converted by the AC / DC converter. It is possible to reduce the power consumption of .4 W (= 152.8 W-129.4 W).

  Thereby, it is possible to improve the overall efficiency while ensuring the stable operation of the fuel cell power generator 101.

  In the present embodiment, the small-capacity switching means 120 and the large-capacity switching means 124 are configured by diodes, but switching elements such as FETs and transistors may be used. In that case, it is necessary to turn on / off the previous switch element in accordance with the transition of the control state of the fuel cell power generation apparatus 101 such as stop / start / power generation / termination.

(Embodiment 2)
FIG. 8 is a configuration diagram of a fuel cell power generator according to the second embodiment of the present invention.

  Components having the same configurations as those of the first embodiment are denoted by the same reference numerals, and description thereof is simplified.

  The difference from the first embodiment is that the output of the small-capacity AC / DC converter 118 is connected to the small-capacity power consumption means 121 via the switch 125. Since the power consumption in the small-capacity power consumption means 121 is as small as 12 mW, the switch 125 is preferably composed of a small power FET or a transistor.

  The operation as the fuel cell power generation apparatus 101 is the same as that of the first embodiment, and the difference is the operation related to the power supply block. Below, operation | movement is demonstrated about a difference.

  FIG. 9 is an operation flowchart of the small-capacity power supply 116. The difference from FIG. 2 of the first embodiment is that step S104 is deleted and steps S301 to S303 are added.

  The control means 109 turns on the switch 125 10 seconds before the end of power generation and starts supplying power to the small capacity power consumption means 121 (S301, S302). Therefore, when the transition from power generation to termination is made 10 seconds later, the small-capacity AC / DC converter 118 is in a state capable of responding to the rapid increase in output, and the small-capacity DC / DC converter 119 is switched to the small-capacity AC / DC converter 118. Even when switching the output, the power supply can be continued stably without reducing the output voltage.

  Thereby, since the low power consumption means 121 can be made effective only when necessary, unnecessary power consumption can be suppressed and the overall efficiency of the fuel cell power generation apparatus 101 can be improved.

  Note that the switch 125 remains off until it exceeds 10 seconds until the end of power generation.

  In this embodiment, the switch 125 is turned on for 10 seconds before the end of power generation, but there is no particular problem as long as the time is sufficient for the small capacity AC / DC converter 118 to stabilize. In addition, a shorter ON period of the switch 125 is preferable from the viewpoint of overall efficiency, but if the configuration is such that the power is always turned on during power generation in conjunction with the small capacity DC / DC converter 119, the control means 107 can No command is required, and it can be realized by a closed circuit in the small-capacity power supply 116, and the independence of the circuit can be enhanced.

  As described above, the fuel cell power generation apparatus according to the present invention uses only a small capacity power source when the required power is low and uses a small capacity power source and a large capacity power source when the required power is large for start-up, power generation, and termination. Power supply for operation, the power efficiency of small-capacity power supplies and large-capacity power supplies can be optimized according to the capacity, and power consumption can be reduced and overall efficiency can be improved. The present invention can also be applied as a power source of a device that greatly varies in power consumption and requires constant energization. In addition, the power to operate the fuel cell power generator is supplied by switching the two sources of the stack and commercial AC in a stable manner according to the power generation state, thus reducing power conversion losses and improving overall efficiency. Therefore, the present invention can be applied to general home power generators such as engine power generators and solar power generators.

1 is a configuration diagram of a fuel cell power generator according to Embodiment 1 of the present invention. Operation flowchart of small capacity power supply of the same fuel cell power generator Operation flow chart of the large capacity power supply of the fuel cell power generator Characteristic chart showing power supply efficiency characteristics of small capacity AC / DC converter of the same fuel cell power generator Characteristic chart showing power supply efficiency characteristics of large capacity AC / DC converter of the same fuel cell power generator Characteristic diagram showing the power supply efficiency characteristics of the small capacity DC / DC converter of the fuel cell power generator Characteristic chart showing power supply efficiency characteristics of large capacity DC / DC converter of the same fuel cell power generator Configuration diagram of fuel cell power generator in Embodiment 2 of the present invention Operation flowchart of small capacity power supply of the same fuel cell power generator Configuration diagram of conventional fuel cell power generator

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Fuel cell power generator 102 Distribution board 103 Commercial alternating current 104 Domestic load 105 Power generation block 106 Power supply block 107 Stack 108 Inverter 109 Control means 110 Hydrogen generator 111 Blower 112 Hot water storage tank 113 Waste heat recovery means 114 Actuator 115 Sensor 116 Small capacity Power supply 117 Large capacity power supply 118 Small capacity AC / DC converter 119 Small capacity DC / DC converter 120 Small capacity switching means 121 Small capacity power consumption means 122 Large capacity AC / DC converter 123 Large capacity switching means 124 Large capacity DC / DC converter 125 switch

Claims (6)

A power generation block, a power supply block for supplying power to the power generation block, and a control means for controlling the operation of the power generation block and the power supply block,
The power generation block includes a hydrogen generator that generates a fuel gas mainly composed of hydrogen from a hydrocarbon-based raw material gas and water, and a stack that generates power by reacting the fuel gas and the oxidant gas from the hydrogen generator. And an inverter that converts DC power from the stack into AC power,
The power supply block includes the control means, a small capacity power source that supplies power to the small capacity power device in the power generation block, and a large capacity power source that supplies power to the large capacity power device in the power generation block,
The small-capacity power supply includes a small-capacity AC / DC converter that converts commercial alternating current to a first predetermined voltage, a small-capacity DC / DC converter that converts an output from the stack to a second predetermined voltage, and the small-capacity A small-capacity power consuming means for consuming predetermined power to a low output voltage side of the AC / DC converter and the small-capacity DC / DC converter, and the first predetermined when the power generation block is started, terminated and stopped A small capacity switching means for outputting a voltage to the small capacity power device of the power generation block and outputting the second predetermined voltage to the small capacity power device of the power generation block when generating power;
The large-capacity power source includes a large-capacity AC / DC converter that converts the commercial alternating current into a third predetermined voltage, and the third predetermined voltage when the power generation block is activated and terminated. Outputs to the power device and outputs the stack output to the large-capacity power device of the power generation block when generating power, and stops output of the power generation block to the large-capacity power device when stopped A fuel cell power generator having a large capacity switching means. 2. The fuel cell power generator according to claim 1, wherein the large-capacity power source includes a large-capacity DC / DC converter that converts an output of the large-capacity switching unit into a fourth predetermined voltage. 3. The fuel cell power generator according to claim 1, wherein at least one of the small capacity switching unit and the large capacity switching unit is configured by a semiconductor element. 4. The small-capacity power supply is configured such that the first predetermined voltage is lower than the second predetermined voltage, and the small-capacity switching means is configured by an OR circuit of a diode. Fuel cell power generator. The fuel cell power generator according to any one of claims 1 to 4, further comprising a switch for turning on and off the small-capacity power consumption means. 6. The fuel cell power generator according to claim 5, wherein the switch is turned on for a predetermined period before switching timing between the first predetermined voltage and the second predetermined voltage.