Electric power control system

Abstract

The present invention discloses an electric power control system. The electric power control system (10) includes a first fuel cell system (16A) and a second fuel cell system (16B), and a waste power unit (98) connected in series with a switch unit (96). The waste power unit (98) and the switch unit (96) are connected in parallel to each fuel cell system. When one or more power supply systems (12) are started, a control unit (110) selectively implements charging control and waste power control based on at least one of temperature information and power storage information. The charging control suppresses voltage rise by supplying power from the power supply system (12) to the power storage device. The waste power control suppresses voltage rise by supplying power from the power supply system (12) to the waste power unit (98). Thus, the output efficiency at the time of startup can be improved.

Description

Technical Field

[0001] The present invention relates to an electric power control system for controlling the voltage of a fuel cell system when it is started. Background Art

[0002] As disclosed in JP2020-31030A, an electric power control system having a fuel cell system controls the power generation voltage of a fuel cell stack by a VCU (voltage converter), for example, a DC / DC converter. Summary of the Invention

[0003] However, in an electric power control system, when the voltage is adjusted using a VCU installed in a fuel cell system, the power output efficiency during startup decreases. JP2020-31030A discloses an electric power control system comprising multiple fuel cell systems (including a fuel cell stack). In this electric power control system, the fact that each fuel cell system includes a VCU significantly reduces output efficiency.

[0004] The purpose of the present invention is to solve the above-mentioned technical problems.

[0005] To achieve the above-mentioned object, one embodiment of the present invention is an electric power control system comprising one or more power supply systems, a power storage device, a power storage information acquisition unit, a temperature information acquisition unit, and a control unit, wherein the one or more power supply systems include a fuel cell system and a waste electricity unit, the waste electricity unit being connected in series with a switch unit and connected in parallel to the fuel cell system together with the switch unit; the power storage device being connected in parallel to the one or more power supply systems; the power storage information acquisition unit acquiring power storage information related to the charge amount of the power storage device; the temperature information acquisition unit acquiring temperature information related to the ambient temperature of the one or more power supply systems; and the control unit controlling the one or more power supply systems. When the one or more power supply systems are started up, the control unit selectively implements charge control and waste electricity control based on at least one of the temperature information and the power storage information. The charging control is control for suppressing a voltage increase of the fuel cell system by supplying electric power from the one or more power supply systems to the power storage device, and the waste power control is control for suppressing a voltage increase of the fuel cell system by supplying electric power from the one or more power supply systems to the waste power section.

[0006] The above-mentioned electric power control system controls the voltage at the time of startup of the fuel cell system with a simple structure, thereby improving the output efficiency at the time of startup.

[0007] The above-mentioned objects, features, and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is an explanatory diagram schematically showing the overall configuration of an electric power control system according to one embodiment of the present invention.

[0009] Figure 2 This is an explanatory diagram schematically showing the structure of a single fuel cell system.

[0010] Figure 3A and Figure 3B This is an explanatory diagram illustrating an example of combining a plurality of single fuel cell systems.

[0011] Figure 4 This is a block diagram showing the functional blocks of the control unit.

[0012] Figure 5 Graph showing control in mode (a) of the electric power control system.

[0013] Figure 6 Graph showing control in mode (b) of the electric power control system.

[0014] Figure 7 Graph showing control in mode (c) of the electric power control system.

[0015] Figure 8A This is a flowchart showing the process flow when starting the startup. Figure 8B This is a flowchart showing the flow of processing in the control of the (a) mode.

[0016] Figure 9A This is a flowchart showing the flow of processing in the control of the (b) mode. Figure 9B This is a flowchart showing the flow of processing in the control of the (c) mode.

[0017] Figure 10 This is an explanatory diagram schematically illustrating the overall configuration of an electric power control system according to the first modification.

[0018] Figure 11 This is an explanatory diagram schematically illustrating the overall configuration of an electric power control system according to a second modification. DETAILED DESCRIPTION

[0019] like Figure 1 As shown, the electric power control system 10 according to one embodiment of the present invention has multiple ( Figure 1There are two) power supply systems 12. The electric power of multiple power supply systems 12 can be controlled. One or more fuel cell systems are provided inside each power supply system 12. Hereinafter, one fuel cell system will be referred to as a single fuel cell system 14. The single fuel cell system 14 generates electricity based on the supplied fuel gas (hydrogen) and oxidant gas (oxygen, air), and outputs the generated power. Such an electric power control system 10 can be applied to large mobile bodies (buses, trucks, ships, aircraft, etc.) that require high voltage and high current, for example. In addition, the objects to which the electric power control system 10 is applicable are not particularly limited. In the following description, one of the two power supply systems 12 possessed by the electric power control system 10 is referred to as the first power supply system 12A, and the other is referred to as the second power supply system 12B.

[0020] First power supply system 12A and second power supply system 12B are connected in parallel. In this embodiment, first power supply system 12A and second power supply system 12B each include two individual fuel cell systems 14. Hereinafter, in first power supply system 12A, first fuel cell system 16A includes one or more individual fuel cell systems 14. In second power supply system 12B, second fuel cell system 16B includes one or more individual fuel cell systems 14.

[0021] like Figure 1 As shown, the first fuel cell system 16A and the second fuel cell system 16B include two individual fuel cell systems 14 connected in series. The first fuel cell system 16A and the second fuel cell system 16B may each include one individual fuel cell system 14, or may include three or more individual fuel cell systems 14. When the first fuel cell system 16A and the second fuel cell system 16B each include a plurality of individual fuel cell systems 14, the individual fuel cell systems 14 may be connected in parallel.

[0022] like Figure 2 As shown, the single fuel cell system 14 includes a fuel cell stack 20, a fuel gas system 22, an oxidant gas system 24, and a refrigerant system 26. The fuel gas system 22 flows fuel gas through the fuel cell stack 20. The oxidant gas system 24 flows oxidant gas through the fuel cell stack 20. The refrigerant system 26 flows refrigerant through the fuel cell stack 20.

[0023] The fuel cell stack 20 includes a plurality of power generation cells 28. Each power generation cell 28 generates electricity through an electrochemical reaction between a fuel gas and an oxidant gas. Each power generation cell 28 includes a membrane electrode assembly 30 and a pair of separators 38a and 38b that sandwich the membrane electrode assembly 30. The membrane electrode assembly 30 includes an electrolyte membrane 32, an anode electrode 34, and a cathode electrode 36. The anode electrode 34 is provided on one surface of the electrolyte membrane 32, and the cathode electrode 36 is provided on the other surface of the electrolyte membrane 32. A fuel gas flow path 40 for the flow of fuel gas is formed on the surface of the separator 38a facing the membrane electrode assembly 30. An oxidant gas flow path 42 for the flow of oxidant gas is formed on the surface of the separator 38b facing the membrane electrode assembly 30. Furthermore, a plurality of power generation cells 28 are stacked, and a refrigerant flow path 44 for the flow of refrigerant is formed between the facing surfaces of the separators 38a and 38b.

[0024] The fuel cell stack 20 also has multiple communication holes (not shown) (fuel gas communication holes, oxidant gas communication holes, and coolant communication holes). These multiple communication holes allow the fuel gas, oxidant gas, and coolant to flow in the stacking direction of the power generation cells 28. The fuel gas communication hole communicates with the fuel gas flow path 40. The oxidant gas communication hole communicates with the oxidant gas flow path 42. The coolant communication hole communicates with the coolant flow path 44.

[0025] Fuel gas flows from the fuel gas system 22 into the fuel gas flow path 40 via the fuel gas manifold on the inlet side of the fuel cell stack 20. The fuel gas is used to generate electricity in the anode electrode 34. Fuel exhaust gas used for power generation flows from the fuel gas flow path 40 to the fuel gas manifold on the outlet side. The fuel exhaust gas is then discharged from the fuel cell stack 20 to the fuel gas system 22. The fuel exhaust gas contains unreacted hydrogen.

[0026] The oxidant gas flows from the oxidant gas system 24 into the oxidant gas flow path 42 via the oxidant gas communication holes on the inlet side of the fuel cell stack 20. The oxidant gas is used to generate electricity at the cathode electrode 36. The oxidant exhaust gas used for power generation flows from the oxidant gas flow path 42 to the oxidant gas communication holes on the outlet side. The oxidant exhaust gas is then discharged from the fuel cell stack 20 to the oxidant gas system 24.

[0027] The coolant flows from the coolant device 26 into the coolant flow path 44 through the coolant communication holes on the inlet side of the fuel cell stack 20. The coolant cools each power generation cell 28. After cooling each power generation cell 28, the coolant flows from the coolant flow path 44 to the coolant communication holes on the outlet side and is discharged from the fuel cell stack 20 to the cooling device.

[0028] Each power generation cell 28 of the fuel cell stack 20, constructed as described above, generates electricity based on the supplied fuel gas and oxidant gas. Terminal plates (not shown) are provided at both ends of the stacked structure of the power generation cells 28. The power generated by the fuel cell stack 20 is output from the terminal plates to the outside of the fuel cell stack 20.

[0029] The fuel gas system device 22 has a fuel gas supply channel 46, a fuel gas exhaust channel 48, and a fuel gas circulation channel 50. The fuel gas system device 22 forms a circulation loop that returns unreacted hydrogen gas discharged into the fuel gas exhaust channel 48 to the fuel gas supply channel 46. The fuel gas supply channel 46 has a tank body 52 at one end of the upstream end for storing high-pressure fuel gas. The fuel gas supply channel 46 has an injector 54 and an ejector 56 in sequence from the tank body 52 to the fuel cell stack 20. The fuel gas exhaust channel 48 has a gas-liquid separator 58 that separates liquid water and gas contained in the fuel exhaust gas. The exhaust channel 60 is connected to the gas-liquid separator 58. The purification channel 62 is connected to the fuel gas circulation channel 50.

[0030] The oxidant gas system 24 includes an oxidant gas supply passage 64, an oxidant gas exhaust passage 66, and an oxidant gas bypass passage 68. An air pump 70 is provided in the oxidant gas supply passage 64. The air pump 70 compresses atmospheric air (air) and supplies it to the fuel cell stack 20. The oxidant gas supply passage 64 includes a humidifier 72. The humidifier 72 humidifies the oxidant gas in the oxidant gas supply passage 64 using moisture contained in the oxidant off-gas in the oxidant gas exhaust passage 66. The exhaust passage 60 (purge passage 62) of the fuel gas system 22 is connected to the oxidant gas exhaust passage 66.

[0031] The refrigerant device 26 includes a refrigerant supply passage 74 and a refrigerant discharge passage 76. The refrigerant supply passage 74 and the refrigerant discharge passage 76 are connected to a radiator 78 that cools the refrigerant. A refrigerant pump 80 is provided on either the refrigerant supply passage 74 or the refrigerant discharge passage 76.

[0032] When the first fuel cell system 16A and the second fuel cell system 16B have a plurality of single fuel cell systems 14, various configurations can be employed. Figure 2 The single fuel cell system 14 shown may be a single fuel cell system, or a part of the components of the single fuel cell system 14 may be shared.

[0033] For example, Figure 3AAs shown, the first fuel cell system 16A and the second fuel cell system 16B can also share the tank 52 of the fuel gas system device 22 and the air pump 70 of the oxidant gas system device 24. This allows multiple fuel cell stacks 20 to be connected in parallel by appropriately setting the paths of each device. In short, the first fuel cell system 16A and the second fuel cell system 16B include multiple single fuel cell systems 14. These multiple single fuel cell systems 14 only need to include multiple fuel cell stacks 20, and there are no particular limitations on other structures for circulating the fuel gas, oxidant gas, and refrigerant.

[0034] Or, as Figure 3B As shown, the first fuel cell system 16A and the second fuel cell system 16B can have multiple fuel cell stacks 20 connected in series. That is, in the first fuel cell system 16A and the second fuel cell system 16B, the fuel gas supply channel 46 is connected to one fuel cell stack 20, and the fuel gas exhaust channel 48 is connected to the other fuel cell stack 20. Furthermore, the fuel gas outlet of one fuel cell stack 20 and the fuel gas inlet of the other fuel cell stack 20 are connected via a fuel gas relay channel 82. Similarly, the oxidant gas supply channel 64 is connected to one fuel cell stack 20, and the oxidant gas exhaust channel 66 is connected to the other fuel cell stack 20. Furthermore, the oxidant gas outlet of one fuel cell stack 20 and the oxidant gas inlet of the other fuel cell stack 20 are connected via an oxidant gas relay channel 84.

[0035] return Figure 1 The electric power control system 10 has a battery 90 (power storage device) connected in parallel with the first power supply system 12A and the second power supply system 12B. The first power supply system 12A has a first fuel cell system 16A, and the second power supply system 12B has a second fuel cell system 16B. The battery 90 is a high-capacity battery that can store the electric power of multiple power supply systems 12. In addition, Figure 1 In the embodiment, the electric power control system 10 is configured to include one battery 90 . However, the electric power control system 10 may include a plurality of batteries 90 .

[0036] The battery 90 has a charge capacity detection unit 92. The charge capacity detection unit 92 obtains the charge capacity (state of charge: SOC) of the battery 90. The method for detecting the charge capacity of the battery 90 can use a well-known method. The charge capacity detection unit 92 can be appropriately constructed according to the method adopted. For example, the charge capacity detection unit 92 has a processing circuit and a storage unit. The processing circuit includes a processor such as a CPU. The storage unit includes a volatile memory such as a RAM, a non-volatile memory such as a ROM, and a flash memory. The storage unit stores programs, etc. The charge capacity detection unit 92 obtains the charge capacity of the battery 90 by executing the program through the processing circuit. The detection process of the charge capacity of the battery 90 by the charge capacity detection unit 92 can also be implemented by an electronic circuit including an ASIC, an FPGA or other integrated circuits.

[0037] The electric power control system 10 also includes a voltage regulator (hereinafter referred to as a battery VCU 94 ) connected in series with the battery 90 . The battery VCU 94 is connected in parallel with the first power system 12A and the second power system 12B. The battery VCU 94 includes a DC / DC converter (buck-buck converter), a contactor, and other components. The contactor connects and disconnects the electric power supply path. Under the control of the control unit 110 , described later, the battery VCU 94 steps down the generated voltage supplied from the first power system 12A and the second power system 12B, and steps up the output voltage from the battery 90 .

[0038] The first power supply system 12A includes a waste power unit 98 connected in series with a switch unit 96 (hereinafter referred to as the first switch 96A). The waste power unit 98 and the first switch 96A are connected in parallel to the first fuel cell system 16A. The waste power unit 98 includes a waste power resistor (hereinafter referred to as the first waste power resistor 98A) having an appropriate resistance value. Furthermore, the first power supply system 12A includes a first voltmeter 100A for detecting the output voltage of the first fuel cell system 16A. Furthermore, the first power supply system 12A includes a first diode 102A provided on the power output wiring of the first power supply system 12A. The first diode 102A blocks the power supplied from the battery 90 or the second power supply system 12B to the first power supply system 12A.

[0039] The second power supply system 12B includes a waste power unit 98 connected in series with a switch unit 96 (hereinafter referred to as the second switch 96B). The waste power unit 98 and the second switch 96B are connected in parallel to the second fuel cell system 16B. The waste power unit 98 includes a waste power resistor (hereinafter referred to as the second waste power resistor 98B) having an appropriate resistance value. Furthermore, the second power supply system 12B includes a second voltmeter 100B for detecting the output voltage of the second fuel cell system 16B. Furthermore, the second power supply system 12B includes a second diode 102B provided on the power output wiring of the second power supply system 12B. The second diode 102B blocks the power supplied from the battery 90 or the first power supply system 12A to the second power supply system 12B.

[0040] The first waste resistor 98A and the second waste resistor 98B can be adapted to be heaters (not shown) installed in the mobile object for increasing the temperature. Examples of such heaters include a heater for increasing the temperature of the battery 90, a heater for increasing the temperature of each component of the fuel cell system 14, and a seat heater for the mobile object. The resistance value of the first waste resistor 98A and the resistance value of the second waste resistor 98B can be the same or different.

[0041] Furthermore, the electric power control system 10 includes a temperature sensor 104 and a control unit 110. The temperature sensor 104 acquires temperature information related to the ambient temperature of the mobile object (power supply system 12). The control unit 110 receives the temperature information from the temperature sensor 104 and the power storage information (the charge amount of the battery 90) from the charge amount detection unit 92 and processes them. The temperature sensor 104 can be, for example, an external air temperature sensor (not shown), a refrigerant outlet temperature sensor 104a (see Figure 2 ) etc. The external temperature sensor detects the external temperature of the mobile object. The refrigerant outlet temperature sensor 104a is provided in the refrigerant discharge passage 76 of the single fuel cell system 14. The temperature sensor 104 is not particularly limited as long as it can obtain temperature information of the power supply system.

[0042] The control unit 110 has a processing circuit including one or more processors, a memory, an input / output interface, an electronic circuit, and a communication module (all not shown). A plurality of functional blocks for controlling the operation of the electric power control system 10 are formed in the control unit 110. The operation of the electric power control system 10 is controlled by executing a program not shown in the memory by one or more processors. In addition, at least a part of each functional block may also be composed of an integrated circuit such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or an electronic circuit including discrete devices. The memory can be applicable to various drives (HDD, SSD, etc.), or include a memory attached to a processor or an integrated circuit.

[0043] The control unit 110 controls the operation of the first power system 12A, the second power system 12B, and the battery VCU 94. The control unit 110 may also serve as a control unit for the single fuel cell system 14 (not shown). The control unit for the single fuel cell system 14 controls the operation of each structure of the first fuel cell system 16A and the second fuel cell system 16B. In addition, the control unit 110 appropriately controls the rising voltage of the first power system 12A and the second power system 12B when the first power system 12A and the second power system 12B are started. Accordingly, the output efficiency of each power system 12 is improved. Specifically, as Figure 4 As shown, the control unit 110 includes a charge amount acquisition unit 112 , a temperature acquisition unit 114 , a voltage acquisition unit 116 , a determination processing unit 118 , a first power supply control unit 120 , a second power supply control unit 122 , and a VCU control unit 124 .

[0044] The charge amount acquisition unit 112 acquires power storage information from the charge amount detection unit 92 at appropriate times and stores it in memory. The charge amount acquisition unit 112 outputs this power storage information to the determination processing unit 118. The temperature acquisition unit 114 acquires temperature information from the temperature sensor 104 at appropriate times and stores it in memory. The temperature acquisition unit 114 outputs this temperature information to the determination processing unit 118. The voltage acquisition unit 116 acquires the first voltage information detected by the first voltmeter 100A and the second voltage information detected by the second voltmeter 100B at appropriate times and stores it in memory. The voltage acquisition unit 116 outputs each voltage information to the determination processing unit 118.

[0045] The determination processing unit 118 determines the control details of the power control system 10 based on the temperature information, power storage information, first voltage information, and second voltage information. This determination of the control details of the power control system 10 is performed at the start of each power supply system 12 and while each power supply system 12 is in the startup state. Therefore, the determination processing unit 118 includes a start determination processing unit 126 that operates at the start of startup and a startup determination processing unit 128 that operates during the startup state (startup) after the start of startup. The determination processing unit 118 also includes a temperature threshold Tht (predetermined temperature) for comparison with the temperature information and a charge level threshold Thq (predetermined charge level) for comparison with the power storage information. Furthermore, the determination processing unit 118 includes a degradation suppression voltage threshold Thv, a VCU operation permission voltage Va, a VCU stop voltage Vb, and a chargeable threshold Thc for comparison with the first and second voltage information during the startup state. The VCU operation permission voltage Va and the VCU stop voltage Vb are values ​​lower than the degradation suppression voltage threshold Thv and define the operating voltage range (hysteresis width) of the battery VCU 94.

[0046] The power control system 10 according to this embodiment selectively implements charging control and waste power control. Charging control involves supplying power from each power supply system 12 to the battery 90 to suppress voltage increases. Waste power control involves supplying power from each power supply system 12 to the waste power unit 98 to suppress voltage increases. Charging control and waste power control are performed by the first power supply system 12A and the second power supply system 12B, respectively. Therefore, the first power supply control unit 120 performs charging control and waste power control for the first power supply system 12A based on instructions from the determination processing unit 118 (start determination processing unit 126 and startup determination processing unit 128). Similarly, the second power supply control unit 122 performs charging control and waste power control for the second power supply system 12B based on instructions from the determination processing unit 118 (start determination processing unit 126 and startup determination processing unit 128). Furthermore, the VCU control unit 124 controls the operation of the battery VCU 94 based on instructions from the startup determination processing unit 128.

[0047] When each power supply system 12 starts to start, the start determination processing unit 126 sets appropriate control processing based on the comparison results of temperature information and temperature threshold Tht and the comparison results of power storage information and charge amount threshold Thq as shown in the following modes (a) to (d).

[0048] (a) Temperature information < temperature threshold Tht and power storage information < charge amount threshold Thq

[0049] → Implement waste power control first, and then implement charging control.

[0050] (b) Temperature information ≧ temperature threshold Tht and power storage information < charge amount threshold Thq

[0051] →Only charging control is implemented.

[0052] (c) Temperature information < temperature threshold Tht and power storage information ≧ charge amount threshold Thq

[0053] →First, waste power control and discharge of the battery 90 are performed, and then charging control is performed.

[0054] (d) Temperature information ≧ temperature threshold Tht and power storage information ≧ charge amount threshold Thq

[0055] → Waste power control is implemented. However, if the charge level of the battery 90 decreases, the control switches to charging control.

[0056] On the other hand, when waste power control is implemented in the aforementioned modes (a) and (c), the startup determination processing unit 128 uses the first and second voltage information in addition to temperature information and power storage information to determine whether to switch from waste power control to charging control. The control in each mode is described in detail below.

[0057] Mode (a) is a startup method used when the electric power control system 10 is in a low-temperature environment and the battery 90 has room to charge when the first power supply system 12A and the second power supply system 12B begin startup. The start determination processing unit 126 begins processing in mode (a) when it determines that the temperature information is less than the temperature threshold Tht and the stored power information is less than the charge level threshold Thq.

[0058] In this case, if Figure 5 As shown, the start determination processing unit 126 outputs a waste power control command to the first power supply control unit 120 and the second power supply control unit 122. In response, the first power supply control unit 120 turns on the first switch 96A of the first power supply system 12A at the start time t0. The second power supply control unit 122 turns on the second switch 96B of the second power supply system 12B at the start time t0. As a result, the power generated by the first fuel cell system 16A can be supplied to the first waste power resistor 98A. Furthermore, the power generated by the second fuel cell system 16B can be supplied to the second waste power resistor 98B.

[0059] In addition, the first fuel cell system 16A and the second fuel cell system 16B are started at the start time point t0 under the control of the control unit 110 for the fuel cell. However, since each fuel cell stack 20 generates electricity based on the supplied fuel gas and oxidant gas, the output of the generated power is delayed. In addition, sometimes, the first fuel cell system 16A and the second fuel cell system 16B are affected by the freezing of auxiliary equipment or the piping layout, which causes deviations in the supply of fuel gas and oxidant gas to each fuel cell stack 20. For example, Figure 5 , an example is shown in which power generation by the first fuel cell system 16A and power generation by the second fuel cell system 16B starts. The first fuel cell system 16A starts power generation at time t1. The second fuel cell system 16B starts power generation at time t2, which is later than time t1.

[0060] As a result, the generated voltage of the first fuel cell system 16A gradually increases from time t1. In response, the current value of the first waste resistor 98A also increases. By supplying generated power to the first waste resistor 98A, each fuel cell stack 20 of the first fuel cell system actively generates electricity, promoting the generation of warm air.

[0061] Furthermore, the startup determination processing unit 128, which operates after the start, monitors the first voltage information. Furthermore, the startup determination processing unit 128 determines whether the generated voltage of the first fuel cell system 16A has reached the VCU operation-permitting voltage Va. Furthermore, if the generated voltage of the second fuel cell system 16B rises first, the startup determination processing unit 128 determines whether the generated voltage of the second fuel cell system 16B has reached the VCU operation-permitting voltage Va based on the second voltage information. If the generated voltage of the first fuel cell system 16A is less than the VCU operation-permitting voltage Va, the startup determination processing unit 128 continues waste power control of the first power supply system 12A.

[0062] At time tx, when the generated voltage of the first fuel cell system 16A reaches or exceeds the VCU operation permission voltage Va, the startup determination processing unit 128 outputs a charge control command to the first power supply system 12A and the VCU control unit 124. In response, the first power supply control unit 120 opens the first switch 96A, and the VCU control unit 124 activates the battery VCU 94, switching to voltage control based on the battery VCU 94. As a result, the operation of the battery VCU 94 suppresses the voltage increase of the generated power of the first fuel cell system 16A to below the degradation suppression voltage threshold Thv, while simultaneously charging the battery 90.

[0063] The startup determination processing unit 128 also monitors the second voltage information while implementing waste power control for the second power supply system 12B, which begins power generation at time t2. The generated voltage of the second fuel cell system 16B gradually increases, and accordingly, the current value of the second waste power resistor 98B increases. However, because the battery VCU 94 is operating, the generated voltage of the second power supply system 12B reaches the same value as the generated voltage of the first power supply system 12A, and then is suppressed from rising further. At time ty, when the generated voltage of the second power supply system 12B reaches the generated voltage of the first power supply system 12A, the startup determination processing unit 128 opens the second switch 96B. Consequently, the power generated by the second fuel cell system 16B and the power generated by the first fuel cell system 16A are both supplied to the battery 90, charging the battery 90.

[0064] Next, mode (b) is a startup method for the case where the electric power control system 10 is at room temperature and the battery 90 has room to charge when the first power supply system 12A and the second power supply system 12B begin startup. The start determination processing unit 126 begins processing in mode (b) when it determines that the temperature information is above the temperature threshold Tht and the stored power information is below the charge level threshold Thq.

[0065] In this case, if Figure 6 As shown, the start determination processing unit 126 outputs a charge control command to the first power supply control unit 120 and the second power supply control unit 122. In response, the first power supply control unit 120 opens the first switch 96A of the first power supply system 12A at the start time t0. Furthermore, the second power supply control unit 122 also opens the second switch 96B of the second power supply system 12B at the start time t0. As a result, the power generated by both the first fuel cell system 16A and the second fuel cell system 16B can be supplied to the battery 90.

[0066] The first fuel cell system 16A and the second fuel cell system 16B are each started at start time t0 under the control of the fuel cell controller 110. Therefore, the power generation voltage of the first fuel cell system 16A gradually increases from time t1.

[0067] Furthermore, the startup determination processing unit 128, which is operating after the start of operation, monitors the first voltage information to determine whether the generated voltage of the first fuel cell system 16A has reached the VCU operation permission voltage Va. If the generated voltage of the first fuel cell system 16A has reached the VCU operation permission voltage Va, the battery VCU 94 is activated under the control of the VCU control unit 124, and the startup determination processing unit 128 performs voltage control based on the battery VCU 94. Consequently, the activation of the battery VCU 94 suppresses the voltage increase of the generated power of the first fuel cell system 16A to below the degradation suppression voltage threshold Thv, while simultaneously charging the battery 90.

[0068] The startup determination processing unit 128 also monitors the second voltage information for the second power supply system 12B, which begins power generation at time t2. Because the battery VCU 94 is operating, the voltage generated by the second power supply system 12B rises to the same value as the voltage generated by the first power supply system 12A and is then suppressed from rising further. Specifically, the power generated by the second fuel cell system 16B and the power generated by the first fuel cell system 16A are suppressed from rising to below the degradation suppression voltage threshold Thv, while the battery 90 is charged.

[0069] Next, mode (c) is a startup method for when the electric power control system 10 is in a low-temperature environment and the battery 90 has a sufficient charge level when the first power supply system 12A and the second power supply system 12B begin startup. The start determination processing unit 126 begins processing in mode (c) when it determines that the temperature information is less than the temperature threshold Tht and the power storage information is greater than the charge level threshold Thq.

[0070] In this case, if Figure 7 As shown, the start determination processing unit 126 outputs waste power control instructions to the first power supply control unit 120 and the second power supply control unit 122. However, the waste power control instruction is output to the first power supply control unit 120 when the power generated by the first fuel cell system 16A reaches the degradation suppression voltage threshold Thv. Similarly, the waste power control instruction is output to the second power supply control unit 122 when the power generated by the second fuel cell system 16B reaches the degradation suppression voltage threshold Thv. Consequently, at the start time t0, the first power supply control unit 120 opens the first switch 96A of the first power supply system 12A, and the second power supply control unit 122 opens the second switch 96B of the second power supply system 12B.

[0071] Furthermore, the battery 90 is discharged to auxiliary equipment such as the air pump 70 (or a heater, an air conditioner, etc.) of the single fuel cell system 14. Therefore, the charge level of the battery 90 gradually decreases from the start time point t0.

[0072] The generated voltage of the first fuel cell system 16A gradually increases from time t1. The startup determination processing unit 128, which is operating after the start, monitors the first voltage information and determines whether the generated voltage of the first fuel cell system 16A has reached the degradation suppression voltage threshold Thv. At time tx, when the generated voltage of the first fuel cell system 16A reaches the degradation suppression voltage threshold Thv, the startup determination processing unit 128 outputs a waste power control command to the first power supply system 12A. In response, the first power supply control unit 120 closes the first switch 96A, directing the generated power of the first fuel cell system 16A to the first waste power resistor 98A. As a result, the generated voltage of the first fuel cell system 16A decreases (voltage rise is suppressed) and falls below the VCU operation-permitting voltage Va.

[0073] Furthermore, the generated voltage of the second fuel cell system 16B begins to gradually rise from time t2. The startup determination processing unit 128 monitors the second voltage information and determines whether the generated voltage of the second fuel cell system 16B has reached the degradation suppression voltage threshold Thv. At time ty, when the generated voltage of the second fuel cell system 16B reaches the degradation suppression voltage threshold Thv, the startup determination processing unit 128 outputs a waste power control command to the second power supply system 12B. In response, the second power supply control unit 122 closes the second switch 96B, directing the generated power of the second fuel cell system 16B to the second waste power resistor 98B. As a result, the generated voltage of the second fuel cell system 16B decreases (voltage rise is suppressed) and falls below the VCU operation-permitting voltage Va.

[0074] Furthermore, during the startup state, the startup determination processing unit 128 determines whether the charge level (power storage information) of the battery 90 has fallen below the chargeable threshold Thc due to discharge. If the power storage information is above the chargeable threshold Thc, the startup determination processing unit 128 continues to control waste power consumption in the first power supply system 12A and the second power supply system 12B. On the other hand, if the power storage information is below the chargeable threshold Thc, the startup determination processing unit 128 outputs a charge control command to the first power supply control unit 120, the second power supply control unit 122, and the VCU control unit 124. In response, the first power supply control unit 120 opens the first switch 96A, the second power supply control unit 122 opens the second switch 96B, and the VCU control unit 124 starts operating the battery VCU 94. Consequently, the operation of the battery VCU 94 suppresses voltage increases in the power generated by the first and second fuel cell systems 16A and 16B, while simultaneously charging the battery 90.

[0075] Furthermore, in mode (d), the battery 90 is not charged by essentially performing waste power control for the first power supply system 12A and waste power control for the second power supply system 12B. On the other hand, when the first fuel cell system 16A and the second fuel cell system 16B are operating, the battery 90 supplies power to auxiliary equipment, causing the charge level to decrease. Therefore, when the battery 90's power level falls below the rechargeable threshold Thc, the first power supply system 12A, the second power supply system 12B, and the VCU control unit 124 switch from waste power control to charging control. Consequently, control similar to that in mode (c) is performed.

[0076] The electric power control system 10 according to this embodiment is basically configured as described above. Next, its operation (processing flow) will be described.

[0077] As described above, the control unit 110 of the electric power control system 10 implements waste power control and charging control on the first power supply system 12A and the second power supply system 12B. Figure 8A As shown, when the first power supply system 12A and the second power supply system 12B begin startup, the start determination processing unit 126 compares the power storage information with the charge level threshold Thq to determine whether the power storage information is less than the charge level threshold Thq (step S1). If the power storage information is greater than the charge level threshold Thq (step S1: No), the above-mentioned mode (c) or mode (d) is selected (step S3). However, as mentioned above, mode (c) and mode (d) are substantially the same, and mode (c) is essentially implemented regardless of temperature information.

[0078] On the other hand, if the power storage information is less than the charge level threshold Thq (step S1: Yes), the process proceeds to step S2, where the start determination processing unit 126 compares the temperature information with the temperature threshold Tht. It then determines whether the temperature information is less than the temperature threshold Tht (step S2). If the temperature information is greater than the temperature threshold Tht (step S2: No), the start determination processing unit 126 selects mode (b) (step S4). On the other hand, if the temperature information is less than the temperature threshold Tht (step S2: Yes), the start determination processing unit 126 selects mode (a) (step S5).

[0079] In the (a) mode, as described above, the startup determination processing unit 128 implements waste power control of the first power supply system 12A and the second power supply system 12B. Figure 8BAs shown, the single fuel cell system 14 starts to supply fuel gas and oxidant gas. In addition, the startup determination processing unit 128 turns on the first switch 96A and the second switch 96B (step S10). Thereafter, the startup determination processing unit 128 determines whether the power generation voltage of the first fuel cell system 16A and the power generation voltage of the second fuel cell system 16B have reached the VCU operation permission voltage Va (step S11). In order to sequentially switch to charging control starting from the power supply system 12 whose power generation voltage in the first power supply system 12A and the second power supply system 12B has reached the VCU operation permission voltage Va, the startup determination processing unit 128 turns off the switch unit 96 (step S12). When the power generation voltage reaches the VCU operation permission voltage Va, the startup determination processing unit 128 operates the battery VCU 94 to adjust the voltage by the battery VCU 94 and charges the battery 90 (step S13).

[0080] In addition, in the (b) mode, as described above, the startup determination processing unit 128 implements the charging control of the first power supply system 12A and the second power supply system 12B. Figure 9A As shown, the single fuel cell system 14 begins supplying fuel gas and oxidant gas, and the startup determination processing unit 128 opens the first switch 96A and the second switch 96B (step S20). Thereafter, the startup determination processing unit 128 determines whether the generated voltage of the first fuel cell system 16A and the generated voltage of the second fuel cell system 16B have reached the VCU operation permission voltage Va (step S21). If the generated voltage has reached the VCU operation permission voltage Va, the startup determination processing unit 128 activates the battery VCU 94 to adjust the voltage (step S22).

[0081] In addition, in mode (c), if Figure 9BAs shown, the single fuel cell system 14 begins supplying fuel gas and oxidant gas, and the first fuel cell system 16A and the second fuel cell system 16B generate electricity (step S30). Then, the startup determination processing unit 128 determines whether the generated voltage of the first fuel cell system 16A or the generated voltage of the second fuel cell system 16B has reached the degradation suppression voltage threshold Thv (step S31). In order to implement waste power control for the power supply system 12 whose generated voltage has reached the degradation suppression voltage threshold Thv, the startup determination processing unit 128 turns on the switch unit 96 (step S32). Furthermore, the startup determination processing unit 128 monitors the power storage information of the battery 90 and determines whether the power storage information has become less than the charge amount threshold Thq (step S33). If the power storage information is above the charge amount threshold Thq, the process returns to step S30 and repeats the same process. On the other hand, when the power storage information becomes smaller than the charge amount threshold value Thq, the first switch 96A and the second switch 96B are opened, the battery VCU 94 is operated, and the control switches to charging control (charging the battery 90 ) (step S34 ).

[0082] Furthermore, the startup determination processing unit 128 monitors power storage information and temperature information even when the first power supply system 12A and the second power supply system 12B are in the startup state, and determines whether to switch between modes (a) to (c) midway. For example, if the temperature information reaches or exceeds the temperature threshold Tht during waste control due to a low charge level in the battery 90 and a temperature information level below the temperature threshold Tht, the system can immediately switch from waste control to charging control. Conversely, if the temperature information falls below the temperature threshold Tht during charging control due to a low charge level in the battery 90 and a temperature information level above the temperature threshold Tht, the system can immediately switch from charging control to waste control. Furthermore, if the charge level in the battery 90 reaches the fully charged state during charging control due to a low charge level in the battery 90, the system can immediately switch to waste control.

[0083] The present invention is not limited to the above-described embodiment and can be modified in various ways consistent with the spirit of the invention. For example, the power control system 10 can be configured to control the power of three or more power supply systems 12 by appropriately applying modifications. Alternatively, it can be configured to control the power of a single power supply system 12.

[0084] In addition, if Figure 10As shown in the first modified example, the power control system 10 can also connect the waste power section 98 (first waste power resistor 98A) of the first power supply system 12A and the waste power section 98 (second waste power resistor 98B) of the second power supply system 12B via a third switch 130. In this case, diodes 134 that regulate the direction of current flow are provided between the wiring 132 provided with the third switch 130 and the first switch 96A, and between the wiring 132 and the second switch 96B. The control unit 110 of the power control system 10 turns on the third switch 130 when implementing waste power control. This allows the power control system 10 to perform waste power control using both the first waste power resistor 98A and the second waste power resistor 98B.

[0085] And, as Figure 11 As shown in the second modified example, the power control system 10 may connect the switch unit 96 and the waste power unit 98 to each individual fuel cell system 14. This allows waste power to be controlled for each individual fuel cell system 14, thereby further improving the power output efficiency during startup.

[0086] The technical ideas and effects that can be grasped according to the above-mentioned embodiments are described below.

[0087] The electric power control system 10 according to one embodiment of the present invention includes one or more power supply systems 12, a power storage device (battery 90), a power storage information acquisition unit (charge amount detection unit 92), a temperature information acquisition unit (temperature sensor 104), and a control unit 110. The one or more power supply systems 12 include a fuel cell system (a single fuel cell system 14) and a waste power unit 98. The waste power unit 98 is connected in series with a switch unit 96 and is connected in parallel to the fuel cell system together with the switch unit 96. The power storage device (battery 90) is connected in parallel to the one or more power supply systems 12. The power storage information acquisition unit (charge amount detection unit 92) acquires the temperature information. The temperature information acquiring unit (temperature sensor 104) acquires temperature information related to the ambient temperature of the one or more power supply systems 12. The control unit 110 controls the one or more power supply systems 12. When the one or more power supply systems 12 are started up, the control unit 110 selectively implements charging control and waste power control based on at least one of the temperature information and the power storage information. The charging control refers to supplying electric power from the one or more power supply systems 12 to the power storage device to suppress a voltage increase, and the waste power control refers to supplying electric power from the one or more power supply systems 12 to the waste power unit 98 to suppress a voltage increase.

[0088] Thus, the power control system 10 controls the voltage of one or more power supply systems 12 during startup using a simple configuration consisting of a waste power unit 98 and a switch unit 96, thereby improving output efficiency during startup. Specifically, by appropriately performing control (charging control and waste power control) based on the charge level of the power storage device (battery 90) or the ambient temperature of the power supply system 12, the control unit 110 can reduce power loss in the fuel cell system (the individual fuel cell system 14) and suppress degradation of the fuel cells caused by voltage increases in the power supply system 12.

[0089] Furthermore, the control unit 110 determines whether the stored power information is above a predetermined charge level and, if so, implements waste power control. This allows the power control system 10 to supply power generated by the fuel cell system (single fuel cell system 14) to the waste power unit 98 when the charge level of the power storage device (battery 90) is high, thereby improving the startup efficiency of the fuel cell system.

[0090] Furthermore, the power storage device (battery 90) discharges during waste power control, and the control unit 110 monitors power storage information during waste power control and switches from waste power control to charge control when the power storage information falls below the chargeable threshold Thc. Consequently, when the power control system 10 switches from waste power control to charge control, it can efficiently charge the power storage device using the power generated by the fuel cell system (single fuel cell system 14).

[0091] Furthermore, control unit 110 performs the following control: when the stored power information is less than a predetermined charge level, it determines whether the temperature information is above a predetermined temperature. If the temperature information is above the predetermined temperature, it performs charging control without waste power control. If the temperature information is less than the predetermined temperature, it performs waste power control and then performs charging control. Thus, when the charge level of the power storage device is low, the power control system 10 can appropriately perform charging control and waste power control based on the ambient temperature of one or more power supply systems 12.

[0092] Furthermore, the power control system 10 includes a voltage conversion unit (battery VCU 94) connected in series with the power storage device (battery 90). During charging control, the control unit 110 uses the voltage conversion unit to ensure that the voltage at the start of one or more power supply systems 12 is less than a predetermined degradation suppression voltage threshold Thv. This allows the power control system 10 to more reliably suppress degradation of the fuel cell.

[0093] Furthermore, one or more power supply systems 12 include a first power supply system 12A and a second power supply system 12B. The first power supply system 12A includes a first fuel cell system 16A as a fuel cell system (one or more individual fuel cell systems 14), a first switch 96A as a switch unit 96, and a first waste resistor 98A as a waste power unit 98. The second power supply system 12B includes a second fuel cell system 16B as a fuel cell system, a second switch 96B as a switch unit 96, and a second waste resistor 98B as a waste power unit 98. The power storage device (battery 90) can be charged with power from each of the first power supply system 12A and the second power supply system 12B. By performing the above-described determination and control, the power control system 10 can significantly improve output efficiency even if the voltages of the first power supply system 12A and the second power supply system 12B rise at different times during startup.

[0094] Furthermore, during waste power control, which is performed when temperature information is below a predetermined temperature, the control unit 110 determines whether the temperature information is above the predetermined temperature. If the temperature information reaches or exceeds the predetermined temperature, the control unit 110 switches from waste power control to charge control even before the output voltage of either the first fuel cell system 16A or the second fuel cell system 16B reaches the predetermined output value. This allows the power control system 10 to smoothly switch from waste power control to charge control in response to temperature changes.

[0095] Furthermore, during waste power control, the control unit 110 turns on the first switch 96A based on the voltage rise time of the first fuel cell system 16A, and turns on the second switch 96B based on the voltage rise time of the second fuel cell system 16B. This allows the power control system 10 to appropriately control the power supply from the first power supply system 12A to the first waste power resistor 98A and the power supply from the second power supply system 12B to the second waste power resistor 98B, thereby further minimizing the loss of generated power.

[0096] Furthermore, first waste power resistor 98A and second waste power resistor 98B are connected via third switch 130, and control unit 110 turns on third switch 130 when implementing waste power control. Thus, electric power control system 10 can utilize waste power unit 98 of either first power supply system 12A or second power supply system 12B when implementing waste power control of the other power supply system, thereby efficiently achieving the effects of temperature increase of waste power unit 98.

Claims

1. An electric power control system, characterized in that: The invention comprises one or more power supply systems, a power storage device, a power storage information acquisition unit, a temperature information acquisition unit, and a control unit, wherein: Each of the one or more power supply systems includes a fuel cell system and a waste power unit, wherein the waste power unit is connected in series with a switch unit and is connected in parallel with the fuel cell system together with the switch unit; The power storage device is connected in parallel to the one or more power supply systems; The power storage information acquisition unit acquires power storage information related to the charge amount of the power storage device; The temperature information acquisition unit acquires temperature information related to the ambient temperature of the one or more power supply systems; The control unit controls the one or more power supply systems. When the one or more power supply systems are activated, the control unit selectively implements charging control and waste power control based on at least one of the temperature information and the power storage information, wherein the charging control is control for suppressing a voltage increase of the fuel cell system by supplying electric power from the one or more power supply systems to the power storage device, and the waste power control is control for suppressing a voltage increase of the fuel cell system by supplying electric power from the one or more power supply systems to the waste power unit.

2. The electric power control system according to claim 1, characterized in that: The control unit determines whether the power storage information is equal to or greater than a predetermined charge amount, and performs the waste power control when the power storage information is equal to or greater than the predetermined charge amount.

3. The electric power control system according to claim 2, characterized in that: The power storage device discharges during the waste power control. The control unit monitors the power storage information during the waste power control, and switches from the waste power control to the charging control when the power storage information becomes smaller than a chargeable threshold value.

4. The electric power control system according to claim 2, characterized in that: The control unit performs the following control: When the power storage information is less than the predetermined charge amount, it is determined whether the temperature information is above a predetermined temperature. When the temperature information is higher than the predetermined temperature, the charging control is performed without performing the waste power control. When the temperature information indicates that the temperature is lower than the predetermined temperature, the waste power control is performed, and then the charging control is performed.

5. The electric power control system according to claim 1, characterized in that: It also includes a voltage conversion unit connected in series with the power storage device. The control unit causes the voltage of the one or more power supply systems at startup to be equal to or lower than a predetermined degradation suppression voltage threshold value through the voltage conversion unit during the charging control.

6. The electric power control system according to any one of claims 1 to 5, characterized in that: The one or more power supply systems include a first power supply system and a second power supply system, The first power supply system includes a first fuel cell system as the fuel cell system, a first switch as the switch unit, and a first waste resistor as the waste unit. The second power supply system includes a second fuel cell system as the fuel cell system, a second switch as the switch unit, and a second waste resistor as the waste unit. The power storage device can be charged with electric power from each of the first power supply system and the second power supply system.

7. The electric power control system according to claim 4, characterized in that: The one or more power supply systems include a first power supply system and a second power supply system, The first power supply system includes a first fuel cell system as the fuel cell system, a first switch as the switch unit, and a first waste resistor as the waste unit. The second power supply system includes a second fuel cell system as the fuel cell system, a second switch as the switch unit, and a second waste resistor as the waste unit. The power storage device can be charged with the electric power of each of the first power supply system and the second power supply system. During the execution of the waste power control performed when the temperature information is lower than the predetermined temperature, the control unit determines whether the temperature information is higher than the predetermined temperature, and when the temperature information reaches or exceeds the predetermined temperature, switches from the waste power control to the charge control even before the output voltage of either the first fuel cell system or the second fuel cell system rises to a predetermined output value.

8. The electric power control system according to claim 6, characterized in that: In the waste power control, the control unit turns on the first switch based on a voltage rise time of the first fuel cell system, and turns on the second switch based on a voltage rise time of the second fuel cell system.

9. The electric power control system according to claim 6, characterized in that: The first waste resistor and the second waste resistor are connected via a third switch. The control unit turns on the third switch when executing the waste power control.

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