Power system, vehicle, and control method for a power system

Abstract

The power system includes: a fuel cell system having a fuel cell stack and a fuel cell water pump; a heat source having a heat source water pump that generates heat by operating; a radiator that exchanges heat with the atmosphere; a cooling passage that thermally connects the fuel cell system, the heat source, and the radiator; and a control device that controls the fuel cell system, the heat source, the radiator, and the cooling passage. The control device controls to switch the rotational speed of the fuel cell water pump by changing to a rotational speed of a predetermined minimum discharge flow rate per unit time, i.e., a first discharge flow rate, and a rotational speed of a second discharge flow rate that is greater than the first discharge flow rate, and controls to switch the rotational speed of the heat source water pump by changing to a rotational speed of a predetermined minimum discharge flow rate per unit time, i.e., a third discharge flow rate, and a rotational speed of a fourth discharge flow rate that is greater than the third discharge flow rate, where the first discharge flow rate < the fourth discharge flow rate, and the second discharge flow rate > the third discharge flow rate.

Description

Technical Field

[0001] The present invention relates to a power system, a vehicle, and a control method for a power system. Background Art

[0002] Patent Document 1 describes "a vehicle, particularly a fuel cell drive unit for a commercial vehicle, including a fuel cell system as an energy source and a fuel cell cooling system for controllably cooling the fuel cell system according to a load".

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-503812. Summary of the Invention

[0004] In a first aspect of the present invention, a power system is provided. The power system includes a fuel cell system having a fuel cell stack and a fuel cell water pump. The power system includes a heat source having a heat source water pump and generating heat by operation. The power system includes a radiator that exchanges heat with the atmosphere. The power system includes a cooling passage that thermally connects the fuel cell system, the heat source, and the radiator. The power system includes a control device that controls the fuel cell system, the heat source, and the radiator. The control device controls to switch the rotational speed of the fuel cell water pump at a rotational speed that becomes a minimum discharge flow rate per unit time, i.e., a first discharge flow rate, and a rotational speed that becomes a second discharge flow rate greater than the first discharge flow rate, and controls to switch the rotational speed of the heat source water pump at a rotational speed that becomes a minimum discharge flow rate per unit time, i.e., a third discharge flow rate, and a rotational speed that becomes a fourth discharge flow rate greater than the third discharge flow rate, where the first discharge flow rate < the fourth discharge flow rate, and the second discharge flow rate > the third discharge flow rate.

[0005] The fuel cell system may further include a flow path and a valve. The flow path of the fuel cell system includes: a main flow path through which, when the valve is in an open state, flows into the fuel cell system, passes through the fuel cell water pump and the fuel cell stack, and flows out of the fuel cell system; and a bypass flow path that is an external flow path that does not pass through the fuel cell water pump and the fuel cell stack when the valve is in a closed state.

[0006] The control device may control the rotational speed of the fuel cell water pump based on at least one of the operating state of the fuel cell system, the operating state of the heat source, and the open / closed state of the valve.

[0007] The control device may control the fuel cell water pump to a rotational speed that becomes the second discharge flow rate and control the heat source water pump to a rotational speed that becomes the third discharge flow rate when the heat source is not operating, and control the fuel cell water pump to a rotational speed that becomes the first discharge flow rate and control the heat source water pump to a rotational speed that becomes the fourth discharge flow rate when the heat source is operating.

[0008] There can be multiple fuel cell systems, and the multiple fuel cell systems and the heat source are respectively connected in parallel on the cooling passage.

[0009] The control device can determine the number of multiple fuel cell systems that need to operate according to the required output of the power system. When the heat source is not operating, the fuel cell water pump of the non-operating fuel cell system is controlled to a rotational speed that becomes the first discharge flow rate, the fuel cell water pump of the operating fuel cell system is controlled to a rotational speed that becomes the second discharge flow rate, and the heat source water pump is controlled to a rotational speed that becomes the third discharge flow rate. When the heat source is operating, the fuel cell water pumps are respectively controlled to a rotational speed that becomes either the first discharge flow rate or the second discharge flow rate, and the heat source water pump is controlled to a rotational speed that becomes the fourth discharge flow rate.

[0010] The control device can, when the heat source is operating, control the fuel cell water pump of the non-operating fuel cell system among the multiple fuel cell systems to a rotational speed that becomes the first discharge flow rate, and control the fuel cell water pump of the operating fuel cell system to a rotational speed that becomes the second discharge flow rate.

[0011] The control device can control the fuel cell water pump to a rotational speed that becomes the first discharge flow rate when the valve is in the closed state, and to a rotational speed that becomes the second discharge flow rate when the valve is in the open state.

[0012] The valve can be an electromagnetic valve that can be opened and closed by the control device. The control device controls the valves of the non-operating fuel cell systems among the multiple fuel cell systems to the closed state, and controls the valves of the operating fuel cell systems to the open state.

[0013] In the second aspect of the present invention, a power system is provided. The power system includes a fuel cell system having a fuel cell stack and a fuel cell water pump. The power system includes a heat source having a heat source water pump and generating heat by operating. The power system includes a radiator that exchanges heat with the atmosphere. The power system includes a cooling passage that thermally connects the fuel cell system, the heat source, and the radiator. The power system includes a control device that controls the fuel cell system, the heat source, and the radiator. The control device controls the rotational speed of the fuel cell water pump according to the temperature of the fuel cell system within a range not less than a first minimum discharge flow rate per unit time, and when the heat source is not operating, controls the rotational speed of the heat source water pump according to the discharge flow rate per unit time of the fuel cell water pump within a range not less than a second minimum discharge flow rate, and when the heat source is operating, controls the rotational speed of the heat source water pump according to the temperature of the heat source.

[0014] The control device can control the rotational speed of the fuel cell water pump based on at least one of the operating state of the fuel cell system, the operating state of the heat source, and the open / closed state of the valve.

[0015] There may be multiple fuel cell systems, and the multiple fuel cell systems and the heat source are respectively connected in parallel on the cooling passage.

[0016] In the third aspect of the present invention, a vehicle is provided. The vehicle has the above power system, and the heat source is a retarder.

[0017] In the fourth aspect of the present invention, a control method for a power system is provided. The power system in the control method of the power system includes a fuel cell system having a fuel cell stack and a fuel cell water pump. The power system includes a heat source having a heat source water pump that generates heat by working. The power system includes a radiator that exchanges heat with the atmosphere. The control method of the power system includes a cooling passage that thermally connects the fuel cell system, the heat source, and the radiator. The battery system includes a control device that controls the fuel cell system, the heat source, and the radiator. The control device performs the following steps: a step of controlling to switch the rotational speed of the fuel cell water pump to a rotational speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., the first discharge flow rate, and a rotational speed that becomes a second discharge flow rate greater than the first discharge flow rate; and a step of controlling to switch the rotational speed of the heat source water pump by changing to a rotational speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., the third discharge flow rate, and a rotational speed that becomes a fourth discharge flow rate greater than the third discharge flow rate, where the first discharge flow rate < the fourth discharge flow rate, and the second discharge flow rate > the third discharge flow rate.

[0018] In the fifth aspect of the present invention, a control method for a power system is provided. The power system in the control method of the power system includes a fuel cell system having a fuel cell stack and a fuel cell water pump. The power system includes a heat source having a heat source water pump that generates heat by working. The power system includes a radiator that exchanges heat with the atmosphere. The control method of the power system includes a cooling passage that thermally connects the fuel cell system, the heat source, and the radiator. The battery system includes a control device that controls the fuel cell system, the heat source, and the radiator. The control device performs the following steps: a step of controlling the rotational speed of the fuel cell water pump according to the temperature of the fuel cell system within a range not less than a predetermined first minimum discharge flow rate per unit time; a step of controlling the rotational speed of the heat source water pump within a range not less than a predetermined second minimum discharge flow rate according to the discharge flow rate per unit time of the fuel cell water pump when the heat source is not operating; and a step of controlling the rotational speed of the heat source water pump according to the temperature of the heat source when the heat source is operating.

[0019] In addition, the above description of the invention does not list all the necessary features of the present invention. Moreover, combinations of the branch features among the above multiple features can also form an invention. Description of the Drawings

[0020] Figure 1 is a diagram showing the schematic structure of the power system 100 in the first embodiment.

[0021] Figure 2 is a diagram showing a first example of the rotational speed control of the water pumps of the respective fuel cell systems 11 to 14 and the retarder 30 in the first embodiment.

[0022] Figure 3 is a diagram showing a second example of the rotational speed control of the water pumps of the respective fuel cell systems 11 to 14 and the retarder 30 in the first embodiment.

[0023] Figure 4 is a diagram showing the mode of the coordinated control in the first embodiment.

[0024] Figure 5 is a flowchart showing the operation of the power system 100 in the first embodiment.

[0025] Figure 6 is a diagram showing the schematic structure of the power system 200 in the second embodiment.

[0026] Figure 7 is a flowchart showing the operation of the power system 200 in the second embodiment.

[0027] Figure 8 Shows an example of the computer 2200. Detailed Embodiments

[0028] Hereinafter, the present invention will be described by way of embodiments of the invention, but the following embodiments do not limit the invention claimed in the claims. In addition, all combinations of the features described in the embodiments are not essential for the solution of the invention.

[0029] Figure 1 is a diagram showing the schematic structure of the power system 100 in the first embodiment. As Figure 1As shown, the power system 100 includes a fuel cell system (FCS1) 11, a fuel cell system (FCS2) 12, a fuel cell system (FCS3) 13, a fuel cell system (FCS4) 14, a cooler 20, and a retarder 30. FCECUs 11d, 12d, 13d, and 14d are respectively connected to the fuel cell systems 11, 12, 13, and 14. A water pump (EWP) 31 and an FCECU 32 are connected to the retarder 30. An FCECU master 50 serving as a control device is connected to the FCECUs 11d to 14d and the FCECU 32. Although not shown, the FCECU master 50 is connected to an ECU that controls the device equipped with the power system 100.

[0030] The power system 100 is installed in a vehicle such as a fuel cell vehicle, for example. The vehicle is a large vehicle such as a large truck, for example. The vehicle obtains driving force from the multiple fuel cell systems 11 to 14 of the power system 100 and is driven. A large vehicle such as a large truck is smoothly driven by the driving force of the multiple fuel cell systems 11 to 14. In addition, the vehicle can be a small vehicle, or can be installed in a moving body other than a vehicle (for example, a ship, an aircraft, a robot), and further, can be installed in a stationary fuel cell system. In the present embodiment, the number of fuel cell systems included in the power system 100 is set to four, namely, the fuel cell systems 11 to 14, but it can be more than or less than this number.

[0031] Although omitted in the present embodiment, the fuel cell systems 11 to 14 may also have other structures. As other structures, for example, an FCVCU (Fuel Cell Voltage Control Unit), a BATTVCU (BATTERY Voltage Control Unit), a PDU (Power Drive Unit) 13a, a MOT (MOTER), a high-voltage auxiliary device, an IPU (Intelligent Power Unit), etc. can be cited.

[0032] The fuel cell system 11 includes a thermal valve (TH) 11a, a water pump (EWP) 11b, and a fuel cell stack (STK) 11c. Similarly, the fuel cell system 12 includes a thermal valve (TH) 12a, a water pump (EWP) 12b, and a fuel cell stack (STK) 12c. The fuel cell system 13 includes a thermal valve (TH) 13a, a water pump (EWP) 13b, and a fuel cell stack (STK) 13c. The fuel cell system 14 includes a thermal valve (TH) 14a, a water pump (EWP) 14b, and a fuel cell stack (STK) 12c.

[0033] In Figure 1 it, the cooling passages for cooling the fuel cell stacks 11c to 14c are shown by solid lines. In the cooling passages, the fuel cell systems 11 to 14, the cooler 20, and the retarder 30 are thermally connected by piping. In the cooling passages, the coolant for cooling the fuel cell stacks 11c to 14c circulates. The cooling passages include main flow paths 41a to 41d and bypass flow paths 42 and 43.

[0034] The main flow paths 41a to 41d are flow paths such that when the thermal valves 11a to 14a are in the open state, the coolant flows into the fuel cell systems 11 to 14, passes through the fuel cell water pumps 11b to 14b and the fuel cell stacks 11c to 14c, and flows out of the fuel cell systems 11 to 14. The bypass flow paths 42 and 43 are flow paths such that when the thermal valves 11a to 14a are in the closed state, the coolant does not pass through the water pumps 11b to 14b and the fuel cell stacks 11c to 14c of the fuel cell systems 11 to 14 and circulates outside the fuel cell systems 11 to 14. The bypass flow path 42 is a flow path for the coolant from the cooler 20 toward the retarder 30. The bypass flow path 43 is a flow path for the coolant from the retarder 30 toward the cooler 20. As Figure 1 shown, the plurality of fuel cell systems 11 to 14 and the retarder 30 are respectively connected in parallel in the cooling passage.

[0035] The fuel cell stacks 11c to 14c are configured by stacking a plurality of unit fuel cells, and include a hydrogen electrode to which hydrogen gas is supplied as fuel gas, an air electrode to which air including oxygen is supplied as oxidant gas, and a cooling passage to which the coolant is supplied. The unit fuel cell is configured by sandwiching a solid polymer electrolyte membrane made of, for example, a solid polymer ion exchange membrane between an anode and a cathode from both sides. Then, hydrogen ions generated by a catalytic reaction in the anode pass through the solid polymer electrolyte membrane, move to the cathode, and electrochemically react with oxygen in the cathode to generate electricity and produce water. In addition, heat is taken away by the coolant flowing in the cooling passage for cooling so that the fuel cell stacks 11c to 14c do not exceed the upper limit temperature due to the heat generated accompanying this power generation.

[0036] The water pumps 11b to 14b are driven by regenerative power from a high-voltage battery or an electric motor to circulate the coolant in the cooling passage.

[0037] When cooling the fuel cell stacks 11c to 14c, the thermal valves 11a to 14a open the passage to allow the cooling water to flow in from the bypass passage 42. In addition, when it is not during the cooling of the fuel cell stacks 11c to 14c, the thermal valves 11a to 14a block the passage from the bypass passage 42 to prevent the inflow of the cooling water. Temperature sensors (not shown) are provided in the thermal valves 11a to 14a, and they are automatically opened and closed based on the temperature of the cooling water around the thermal valves 11a to 14a. Specifically, when the coolant around the thermal valves 11a to 14a is lower than a predetermined temperature, there is no need to cool the coolant, so the passage is blocked to prevent the inflow of the cooling water from the bypass passage 42. On the other hand, when the coolant is higher than the predetermined temperature, it is necessary to cool the coolant, so the passage is opened to allow the cooling water to flow in from the bypass passage 42. The predetermined temperature is, for example, 75 degrees.

[0038] The cooler 20 is a cooling component that exchanges heat between a heat medium and external air. The cooler 20 has a fan 21 as a radiator.

[0039] The retarder 30 is a braking mechanism for a vehicle equipped with the power system 100. In large vehicles such as large trucks, in the case of disc brakes, the braking ability is insufficient, so the added-weight braking is not the usual disc brake, but a fluid type or magnetic type brake called a retarder is adopted. In this embodiment, the retarder 30 is a fluid type retarder. By rotating the rotor of the fluid type retarder, the fluid is circulated between the rotor and the stator, so that resistance can be generated in the fluid, and the braking force of the vehicle can be obtained through the generated resistance. In this embodiment, the retarder 30 is described as a heat source, but as a component equivalent to the retarder, it can also be a heat source other than the retarder.

[0040] The FCECUs 11d to 14d and 32 are computers including a microcomputer, and have a CPU, a ROM, a RAM, input / output devices such as an A / D converter and a D / A converter, and a timer as a timing unit. In the FCECUs 11d to 14d and 32, the CPU reads and executes the programs stored in the ROM.

[0041] FCECUs 11d to 14d are configured to perform energy management of fuel cell systems 11 to 14. FCECU 32 is configured to perform energy management of the retarder 30. In FCECUs 11d to 14d and FCECU 32, the CPU reads and executes the program stored in the ROM, thereby executing the program stored in the ROM. For example, the CPU detects sensor detection values of an opening degree sensor, a pressure sensor, a flow rate sensor, a temperature sensor, a rotational speed sensor of an air pump, etc., which are not shown, the voltage and current of the fuel cell stack, the voltage, current, and rotational speed of the air pump, the voltage, current, and rotational speed of the motor, etc., to control each device.

[0042] FCECUs 11d to 14d and FCECU 32 are comprehensively managed by the FCECU master 50 as a control device. FCECUs 11d to 14d and FCECU 32 receive instructions from the FCECU master 50 and perform control of each device. The FCECU master 50 controls the rotational speed of the water pumps 11b to 14b based on at least one of the operating states of the fuel cell systems 11 to 14, the operating state of the retarder 30, and the open / close states of the heat valves 11a to 14a. The FCECU master 50 determines the number of fuel cell systems 11 to 14 that need to operate according to the output required by the power system 100. FCECU 32 can be provided outside the power system 100 or loaded as a function of an ECU that controls a vehicle equipped with the power system 100, and is configured to control the retarder 30 through a command from the ECU that controls the vehicle equipped with the power system 100, and control the EWP 31 through a command from the ECU that controls the vehicle equipped with the power system 100 based on a signal from the FCECU master 50.

[0043] The circulation path of the cooling water when the heat valve 11a is opened is typically shown as a dotted line route 1 in the fuel cell system 11. During the period when the heat valve 11a is opened, the coolant for cooling the fuel cell stack 11c flows into the interior of the fuel cell system 11 from the bypass flow path 42 and passes through the heat valve 11a. Then, the coolant is boosted by the water pump 11b and supplied to the fuel cell stack 11c. When passing through the cooling passage in the fuel cell stack 11c, the coolant takes heat from the fuel cell stack 11c to cool the fuel cell stack 11c. Then, the heated coolant flows to the bypass flow path 43 (route 1). Then, the heated coolant is sent to the cooler 20, and in the fan 21 of the cooler 20, heat is dissipated to the outside, thereby cooling the coolant. Regarding the other fuel cell systems 12, 13, and 14, the circulation path of the coolant when the heat valves 12a, 13a, and 14a are opened is the same as that of the fuel cell system 11.

[0044] The circulation path of the coolant when the thermal valve 12a is closed is representatively shown as a dotted line route 2 in the fuel cell system 12. During the period when the thermal valve 12a is closed, the coolant flows inside the fuel cell system 12 in a way that circulates between the thermal valve 12a, the water pump 12b, and the fuel cell stack 12c (route 2). Regarding the other fuel cell systems 11, 13, and 14, the circulation path of the coolant when the thermal valves 11a, 13a, and 14a are closed is the same as that of the fuel cell system 12.

[0045] Here, depending on the settings of the rotational speeds of the water pumps 11b to 14b of each of the fuel cell systems 11 to 14 and the water pump 31 of the retarder 30, sometimes the coolant does not flow in the normal direction in the above-mentioned circulation path but flows in the reverse direction. The circulation path of the coolant when it flows in the reverse direction is representatively shown as a dotted line route 3 in the fuel cell system 13. The coolant flows in from the bypass flow path 43 into the fuel cell system 13 and flows into the fuel cell stack 13c (route 3). Regarding the other fuel cell systems 11, 12, and 14, the reverse flow path of the coolant is the same as that of the fuel cell system 13.

[0046] Due to the reverse flow of the coolant, the following problems occur. First, it is necessary to configure a check valve for each of the fuel cell systems 11 to 14 to prevent the reverse flow of the coolant. However, since a check valve is configured for each of the fuel cell systems 11 to 14, the manufacturing cost of the power system 100 increases. Second, in the method without configuring a check valve, since it is necessary to focus on preventing reverse flow and maximize the drive of each of the water pumps 11b to 14b for cooling, the fuel cost of the entire system deteriorates. Third, due to the reverse flow of the coolant, the flow rate of the coolant in each of the fuel cell systems 11 to 14 changes, resulting in condensation or drying. In the first embodiment, in order to prevent the reverse flow of the coolant, the rotational speeds of the water pumps 11b to 14b of each of the fuel cell systems 11 to 14 and the water pump 31 of the retarder 30 are controlled.

[0047] Figure 2 It is a diagram showing a first example of the rotational speed control of the water pumps of each of the fuel cell systems 11 to 14 and the retarder 30 in the first embodiment. In normal control, in order to improve the cooling efficiency, during the period when the retarder 30 is operating, control is performed to reduce the rotational speeds of the water pumps 11b to 14b of each of the fuel cell systems 11 to 14 to reduce the power generation of each of the fuel cell systems 11 to 14. However, when the rotation of the water pumps 11b to 14b of each of the fuel cell systems 11 to 14 is completely stopped, Figure 1 the reverse flow of the coolant as shown in route 3 occurs. Therefore, in the first example, in order to prevent the reverse flow of the coolant, during the period when the retarder 30 is operating, control is performed to rotate the water pumps 11b to 14b at a predetermined minimum rotational speed.

[0048] Specifically, the FCECU main controller 50 controls to switch the rotational speeds of the water pumps 11b to 14b of each fuel cell system 11 to 14 through the first rotational speed and the second rotational speed. The first rotational speed makes the discharge flow rate of the coolant from the water pumps 11b to 14b become the predetermined minimum discharge flow rate per unit time, that is, the first discharge flow rate. The second rotational speed makes the discharge flow rate of the coolant from the water pumps 11b to 14b become the second discharge flow rate which is more than the first discharge flow rate. The first rotational speed and the second rotational speed are determined in consideration of the working / non-working conditions of the retarder 30 and the rotational speed of the water pump 31 of the retarder 30. The first rotational speed is, for example, 4500 rpm.

[0049] When the retarder 30 is not working (OFF), the FCECU main controller 50 controls the rotational speeds of the water pumps 11b to 14b to the second rotational speed. On the other hand, when the retarder 30 is working (ON), the FCECU main controller 50 controls the rotational speeds of the water pumps 11b to 14b to the first rotational speed. Therefore, regardless of the working / non-working conditions of the retarder 30, the water pumps 11b to 14b rotate within a range not less than the first rotational speed, and the first rotational speed becomes the first minimum discharge flow rate per unit time.

[0050] In addition, during normal driving, the retarder 30 does not work, and only each fuel cell system 11 to 14 works. However, when the rotation of the water pump 31 of the retarder 30 is completely stopped when the retarder 30 is not working, a reverse flow of the coolant occurs around the retarder 30. Therefore, in the present embodiment, in order to prevent the occurrence of reverse flow around the retarder 30, during the period when each fuel cell system 11 to 14 works, control is performed to rotate the water pump 31 of the retarder 30 at a predetermined rotational speed.

[0051] Specifically, the FCECU main controller 50 controls to switch the rotational speed of the water pump 31 of the retarder 30 through the third rotational speed and the fourth rotational speed. The third rotational speed makes the discharge flow rate of the coolant from the retarder 30 become the predetermined minimum discharge flow rate per unit time, that is, the third discharge flow rate. The fourth rotational speed makes the discharge flow rate of the coolant from the retarder 30 become the fourth discharge flow rate which is more than the third discharge flow rate. The third rotational speed and the fourth rotational speed are determined in consideration of the rotational speeds of the water pumps 11b to 14b of each fuel cell system 11 to 14 and the temperature of the coolant around the retarder 30. The third rotational speed is, for example, 3000 rpm.

[0052] When the retarder 30 is not working (OFF), the FCECU main controller 50 controls the rotational speed of the water pump 31 to the third rotational speed. When the retarder 30 is working (ON), the FCECU main controller 50 controls the rotational speed of the water pump 31 to the fourth rotational speed.

[0053] The first rotational speed is less than the fourth rotational speed (i.e., the first discharge flow rate < the fourth discharge flow rate). That is, the minimum rotational speed of the water pumps 11b to 14b is less than the rotational speed of the water pump 31 when the retarder 30 operates. Further, the second rotational speed is greater than the third rotational speed (i.e., the second discharge flow rate > the third discharge flow rate). That is, the minimum rotational speed of the water pump 31 is less than the rotational speeds of the water pumps 11b to 14b when the retarder 30 is not operating.

[0054] Figure 3 FIG. is a diagram showing a second example of the rotational speed control of the water pumps of the fuel cell systems 11 to 14 and the retarder 30 in the first embodiment. The second example is an example in which the fuel cell system 11 is controlled individually and the fuel cell systems 12 to 14 are controlled in coordination. Coordinated control is control that causes the rotational speeds of the water pumps of multiple fuel cell systems to operate uniformly. By performing coordinated control on multiple fuel cell systems, it is possible to make the amount of coolant flowing from the multiple fuel cell systems into the bypass flow path 43 and the amount of coolant flowing from the bypass flow path 42 into the multiple fuel cell systems equal, thereby preventing the reverse flow of the coolant. In the second example, when the retarder 30 is not operating, the fuel cell systems 12 to 14 are made to operate and the fuel cell system 11 is made non-operating. Further, when the retarder 30 is operating, the fuel cell system 11 is made to operate and the fuel cell systems 12 to 14 are made non-operating.

[0055] As Figure 3 shown, when the retarder 30 is not operating, the FCECU main controller 50 controls the rotational speeds of the water pumps 12b to 14b to the second rotational speed. On the other hand, when the retarder 30 is not operating, the FCECU main controller 50 controls the rotational speed of the water pump 11b to the first rotational speed. When the retarder 30 is not operating, the FCECU main controller 50 controls the rotational speed of the water pump 31 to the third rotational speed.

[0056] When the retarder 30 is operating, the FCECU main controller 50 controls the rotational speeds of the water pumps 12b to 14b to the first rotational speed. On the other hand, when the retarder 30 is operating, the FCECU main controller 50 controls the rotational speed of the water pump 11b to the second rotational speed. When the retarder 30 is operating, the FCECU main controller 50 controls the rotational speed of the water pump 31 to the fourth rotational speed.

[0057] Figure 4 FIG. is a diagram showing the mode of coordinated control in the first embodiment. In Figure 4 this, "〇" indicates a fuel cell system that performs coordinated control, and "×" indicates a fuel cell system that is not coordinately controlled. As Figure 4 shown, there are 12 modes of coordinated control for the fuel cell systems 11 to 14. Mode (12) is an example in which all of the fuel cell systems 11 to 14 are coordinately controlled, and is the first example in the first embodiment (refer to Figure 2)。The mode (11) is an example of individually controlling the fuel cell system 11 and coordinately controlling the fuel cell systems 12 to 14, and is the second example in the first embodiment (refer to Figure 3 ). Other modes shown in Figure 4 can be used to coordinately control the fuel cell systems 11 to 14.

[0058] Whether to use a certain fuel cell system as an object of coordinated control can be determined according to the opening / closing state of the thermal valve in the fuel cell system. In this case, coordinated control can be performed on the fuel cell system when the temperature of the cooling water is equal to or higher than a predetermined temperature and the thermal valve is open, and individual control can be performed on the fuel cell system when the temperature of the cooling water is lower than the predetermined temperature and the thermal valve is closed.

[0059] Figure 5 is a flowchart showing the operation of the power system 100 in the first embodiment. When the FCECU main controller 50 issues an instruction to drive each water pump (step S01), it is determined whether the switch of the retarder 30 is ON or OFF (step S02). When the switch of the retarder 30 is ON (step S02: YES), the rotation speed of the water pump 31 is set to the fourth rotation speed (step S03), and the rotation speeds of the water pumps 11b to 14b are set to the first rotation speed (step S04). When the switch of the retarder 30 is OFF (step S02: NO), the rotation speed of the water pump 31 is set to the third rotation speed (step S05), and the rotation speeds of the water pumps 11b to 14b are set to the second rotation speed (step S06).

[0060] According to the power system 100 in the first embodiment, in order to prevent the reverse flow of the coolant, the rotation speeds of the water pumps 11b to 14b of the fuel cell systems 11 to 14 and the water pump 31 of the retarder 30 are controlled. Thereby, it is not necessary to arrange a check valve for each of the fuel cell systems 11 to 14 to prevent the reverse flow of the coolant, and the manufacturing cost of the power system 100 can be reduced. Furthermore, problems such as condensation or drying accompanying the reverse flow of the coolant can be prevented, and furthermore, the fuel cost of the power system 100 can be improved.

[0061] Figure 6FIG. is a diagram showing a schematic configuration of the power system 200 in the second embodiment. Hereinafter, only the configuration different from that in the first embodiment in the second embodiment will be described, and the same reference numerals will be given to the same configurations as those in the first embodiment and the description thereof will be omitted. In the power system 100 of the second embodiment, instead of the thermal valves 11a to 14d, electromagnetic valves (EWV) 11e to 14e are provided. The electromagnetic valves 11e to 14e are respectively connected to the FCECUs 11d to 14d, receive instructions from the FCECU master 50, and control opening and closing. The FCECU master 50 controls the electromagnetic valves 11e to 14e of the non-operating fuel cell systems in each of the fuel cell systems 11 to 14 to the closed state, and controls the electromagnetic valves 11e to 14e of the operating fuel cell systems to the open state.

[0062] Figure 7 FIG. is a flowchart showing the operation of the power system 200 in the second embodiment. When the FCECU master 50 issues an instruction to drive the electromagnetic valves 11e to 14e (step S11), it is determined whether the temperature of each of the fuel cell systems 11 to 14 is equal to or higher than a predetermined temperature (step S12). When the temperature of each of the fuel cell systems 11 to 14 is equal to or higher than the predetermined temperature (step S12: YES), the electromagnetic valves 11e to 14e are opened (step S14). When the temperature of each of the fuel cell systems 11 to 14 is not equal to or higher than the predetermined temperature (step S12: NO), the electromagnetic valves 11e to 14e are closed (step S13).

[0063] When the electromagnetic valves 11e to 14e are opened, it is determined whether the switch of the retarder 30 is ON or OFF (step S15). When the switch of the retarder 30 is ON (step S15: YES), the rotation speed of the water pump 31 is set to the fourth rotation speed (step S16), and the rotation speeds of the water pumps 11b to 14b are set to the first rotation speed (step S17). When the switch of the retarder 30 is OFF (step S15: NO), the rotation speed of the water pump 31 is set to the third rotation speed (step S18), and the rotation speeds of the water pumps 11b to 14b are set to the second rotation speed (step S19).

[0064] According to the power system 200 in the second embodiment, the same effects as those of the power system 100 in the first embodiment described above are achieved.

[0065] According to the power system 200 in the second embodiment, solenoid valves 11e to 14e are used in the valves of the fuel cell systems 11 to 14. When thermal valves 11a to 14a are used as in the first embodiment, the thermal valves 11a to 14a open and close according to the temperature of the cooling water. Therefore, the method of controlling the pressure inside the cooling passage entirely depends on the temperature of the cooling water. However, by using the solenoid valves 11e to 14e, it is also possible to control the opening and closing of the valves by conditions other than the temperature of the cooling water, and thus the pressure of the cooling passage can be controlled. In addition, by using the solenoid valves 11e to 14e, an instruction for controlling the pressure inside the cooling passage can be instantaneously transmitted to the solenoid valves 11e to 14e, and the valves can be opened and closed immediately.

[0066] Figure 8 An example of a computer 2200 that can embody multiple aspects of the present invention, either wholly or in part, is shown. The program installed in the computer 2200 can cause the computer 2200 to function as an operation associated with the device of an embodiment of the present invention or one or more parts of the device, or can cause the execution of the operation or the one or more parts, and / or can cause the computer 2200 to execute a process of an embodiment of the present invention or steps of the process. Such a program can be executed by the CPU 2212 so that the computer 2200 performs the determination operations associated with several or all of the blocks in the flowcharts and block diagrams described in this specification.

[0067] The computer 2200 of this embodiment includes a CPU 2212 and a RAM 2214, which are connected to each other through a main controller 2210. The computer 2200 also includes input / output units such as a communication interface 2222, a hard disk drive 2224, a DVD-ROM drive 2226, and an IC card drive, which are connected to the main controller 2210 via an input / output controller 2220. The computer also includes conventional input / output units such as a ROM 2230 and a keyboard 2242, which are connected to the input / output controller 2220 via an input / output chip 2240.

[0068] The CPU 2212 operates according to the programs stored in the ROM 2226 and the RAM 2214, thereby controlling each unit. The graphics controller 2216 acquires image data provided by the CPU 2212 in the RAM 2214, such as a frame buffer, or generated in itself, and displays the image data on the display device 2218.

[0069] The communication interface 2222 communicates with other electronic devices via a network. The hard disk drive 2224 stores programs and data used by the CPU 2212 within the computer 2200. The DVD-ROM drive 2226 reads programs or data from the DVD-ROM 2201 and provides the programs or data to the hard disk drive 2224 via the RAM 2214. The IC card drive reads programs and data from the IC card and / or writes programs and data to the IC card.

[0070] The ROM 2230 stores therein a boot program and the like to be executed by the computer 2200 when activated, and / or a program dependent on the hardware of the computer 2200. The input / output chip 2240 can also connect various input / output units to the input / output controller 2220 via a parallel port, a serial port, a keyboard port, a mouse port, etc.

[0071] The program is provided by a computer-readable medium such as the DVD-ROM 2201 or the IC card. The program is read from the computer-readable medium, installed in the hard disk drive 2224, the RAM 2214, or the ROM 2230, which are also examples of computer-readable media, and executed by the CPU 2212. The information processing described in these programs is read by the computer 2200, resulting in the cooperation between the program and the above various types of hardware resources. The apparatus or method can be configured to implement the operation or processing of information according to the use of the computer 2200.

[0072] For example, in the case of performing communication between the computer 2200 and an external device, the CPU 2212 can execute a communication program loaded in the RAM 2214 and, based on the processing described in the communication program, instruct the communication interface 2222 to perform communication processing. Under the control of the CPU 2212, the communication interface 2222 reads the transmission data stored in the transmission buffer processing area provided in a storage medium such as the RAM 2214, the hard disk drive 2224, the DVD-ROM 2201, or the IC card, and transmits the read transmission data to the network, or writes the received data received from the network to the reception buffer processing area provided on the storage medium, etc.

[0073] In addition, the CPU 2212 can cause all or a required part of a file or database stored in an external storage medium such as the hard disk drive 2224, the DVD-ROM drive 2226 (DVD-ROM 2201), the IC card, etc. to be read into the RAM 2214, and perform various processes on the data on the RAM 2214. The CPU 2212 then writes the processed data back to the external storage medium.

[0074] Various types of information, such as various types of programs, data, data tables, and databases, can be stored in a storage medium and undergo information processing. The CPU 2212 can perform various types of processing (including various types of operations, information processing, conditional judgments, conditional branches, unconditional branches, information retrieval / replacement, etc., described throughout the present disclosure and specified by the instruction sequence of a program) on the data read from the RAM 2214, and write the result back to the RAM 2214. In addition, the CPU 2212 can retrieve information in files, databases, etc. in the storage medium. For example, in the case where a plurality of entries are stored in the storage medium and each of the plurality of entries has an attribute value of a first attribute related to an attribute value of a second attribute, the CPU 2212 can retrieve an entry that matches the condition in which the attribute value of the first attribute is specified from the plurality of entries, and read the attribute value of the second attribute stored in the entry, thereby obtaining the attribute value of the second attribute related to the first attribute that satisfies a predetermined condition.

[0075] The programs or software modules described above can be stored in a computer-readable medium on or near the computer 2200. In addition, a storage medium such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet can be used as a computer-readable medium, whereby the program is provided to the computer 2200 via the network.

[0076] The present invention has been described using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. For those skilled in the art, it is understood that various changes or improvements can be made to the above embodiments. According to the description of the claims, embodiments made by applying the above-described changes or improvements can also be included in the technical scope of the present invention.

[0077] It should be noted that, with respect to the execution order of each process of actions, operation sequences, steps, and steps, etc. in the devices, systems, programs, and methods shown in the claims, the description, and the drawings, as long as words such as "before...", "prior to", etc. are not specifically indicated, and it is not stated that the output of the previous process is used in the subsequent process, it can be implemented in any order. Regarding the action flows in the claims, the description, and the drawings, for convenience, descriptions such as "First," and "Second," etc. are used, but even so, it does not mean that it must be implemented in that order.

[0078] [Description of Reference Numerals]

[0079] 11 - 14 fuel cell systems, 11a - 14a thermal valves, 11b - 14b water pumps, 11c - 14c fuel cell stacks, 20 cooler, 30 retarder, 11d - 14d FCECU, 11b - 14b water pumps 31 FCECU, 41a - 41d main flow paths, 42, 43 bypass flow paths, 100 power system, 50 FCECU main control.

Claims

1. A power system, wherein, comprising: a fuel cell system having a fuel cell stack and a fuel cell water pump; a heat source having a heat source water pump and generating heat by operation; a radiator for heat exchange with the atmosphere; a cooling passage thermally connecting the fuel cell system, the heat source, and the radiator; and a control device for controlling the fuel cell system, the heat source, and the radiator, the control device controls to switch the rotational speed of the fuel cell water pump at a rotational speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., a first discharge flow rate, and at a rotational speed that becomes a second discharge flow rate greater than the first discharge flow rate, the control device controls to switch the rotational speed of the heat source water pump at a rotational speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., a third discharge flow rate, and at a rotational speed that becomes a fourth discharge flow rate greater than the third discharge flow rate, the first discharge flow rate < the fourth discharge flow rate, and the second discharge flow rate > the third discharge flow rate, the fuel cell system further has a flow path and a valve, the flow path of the fuel cell system has: a main flow path, in which when the valve is in an open state, the coolant flows into the fuel cell system, passes through the fuel cell water pump and the fuel cell stack, and flows out of the fuel cell system; and a bypass flow path, in which when the valve is in a closed state, the coolant circulates outside the fuel cell system, the control device controls the rotational speed of the fuel cell water pump based on at least one of the operating state of the fuel cell system, the operating state of the heat source, and the open / closed state of the valve.

2. The power system according to claim 1, wherein when the heat source is not operating, the control device controls the fuel cell water pump to a rotational speed that becomes the second discharge flow rate, and controls the heat source water pump to a rotational speed that becomes the third discharge flow rate, when the heat source is operating, the control device controls the fuel cell water pump to a rotational speed that becomes the first discharge flow rate, and controls the heat source water pump to a rotational speed that becomes the fourth discharge flow rate.

3. The power system according to claim 1, wherein there are a plurality of the fuel cell systems, and the plurality of fuel cell systems and the heat source are respectively connected in parallel on the cooling passage.

4. The power system according to claim 3, wherein the control device determines the number of the plurality of fuel cell systems that need to operate according to the output required by the power system, when the heat source is not operating, the control device controls the fuel cell water pump of the non-operating fuel cell systems to a rotational speed that becomes the first discharge flow rate, controls the fuel cell water pump of the operating fuel cell systems to a rotational speed that becomes the second discharge flow rate, and controls the heat source water pump to a rotational speed that becomes the third discharge flow rate, when the heat source is operating, the control device controls the fuel cell water pumps to rotational speeds that become either the first discharge flow rate or the second discharge flow rate, and controls the heat source water pump to a rotational speed that becomes the fourth discharge flow rate.

5. The power system according to claim 4, wherein when the heat source is operating, the control device controls the fuel cell water pumps of the non-operating fuel cell systems among the plurality of fuel cell systems to rotate at a speed that becomes the first discharge flow rate, and controls the fuel cell water pumps of the operating fuel cell systems to rotate at a speed that becomes the second discharge flow rate.

6. The power system according to claim 5, wherein when the valve is in the closed state, the control device controls the fuel cell water pump to rotate at a speed that becomes the first discharge flow rate, and when the valve is in the open state, the control device controls the fuel cell water pump to rotate at a speed that becomes the second discharge flow rate.

7. The power system according to claim 3, wherein the valve is an electromagnetic valve that can be opened and closed by the control device, the control device controls the valves of the non-operating fuel cell systems among the plurality of fuel cell systems to be in the closed state, and controls the valves of the operating fuel cell systems to be in the open state.

8. A vehicle, wherein it has the power system according to claim 1, the heat source is a retarder.

9. A control method for a power system, wherein the power system includes: a fuel cell system having a fuel cell stack and a fuel cell water pump; a heat source having a heat source water pump and generating heat by operating; a radiator for heat exchange with the atmosphere; a cooling passage thermally connecting the fuel cell system, the heat source, and the radiator; and a control device for controlling the fuel cell system, the heat source, and the radiator, the control device performs the following steps: a step of controlling to switch the rotation speed of the fuel cell water pump at a speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., the first discharge flow rate, and at a speed that becomes a second discharge flow rate greater than the first discharge flow rate; and a step of controlling to switch the rotation speed of the heat source water pump at a speed that becomes a predetermined minimum discharge flow rate per unit time, i.e., the third discharge flow rate, and at a speed that becomes a fourth discharge flow rate greater than the third discharge flow rate, wherein the first discharge flow rate < the fourth discharge flow rate, and the second discharge flow rate > the third discharge flow rate, the fuel cell system further has a flow path and a valve, the flow path of the fuel cell system has: a main flow path, wherein when the valve is in the open state, the coolant flows into the fuel cell system, passes through the fuel cell water pump and the fuel cell stack, and flows out of the fuel cell system; and a bypass flow path, wherein when the valve is in the closed state, the coolant circulates outside the fuel cell system, the control device controls the rotation speed of the fuel cell water pump based on at least one of the operating state of the fuel cell system, the operating state of the heat source, and the open / closed state of the valve.

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