Fuel cell control system

Abstract

This invention provides a fuel cell control system that can improve the vehicle's mileage in the event of an abnormality in inter-ECU communication. [Solution] The fuel cell control system includes a first ECU that determines a target value for the power generated by a fuel cell mounted on a vehicle based on the power required by the vehicle, and a second ECU that receives the target value from the first ECU and controls the power generation of the fuel cell according to the target value. If the second ECU detects an abnormality in communication with the first ECU, it sets the target value to a constant value and controls the power generation of the fuel cell. If the first ECU detects an abnormality in communication with the second ECU, it limits the power required by the vehicle based on the constant value.

Description

Technical Field

[0001] The present invention relates to a fuel cell control system.

Background Art

[0002] Regarding a fuel cell control system, for example, in Patent Document 1, it is described that a vehicle ECU (Electronic Control Unit) calculates a target output power of a fuel cell stack according to the power required by the vehicle and transmits it to a FC (Fuel Cell)-ECU, and the FC-ECU controls the power generation of the fuel cell stack according to the target output power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when an abnormality occurs in the communication between the vehicle ECU and the FC-ECU, the FC-ECU cannot receive the target output power from the vehicle ECU, so the power generation control of the fuel cell stack is stopped. In this case, for example, the vehicle runs only on the remaining power stored in the secondary battery, so the driving distance of the vehicle is significantly reduced compared to the case where the communication is normal.

[0005] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell control system capable of improving the driving distance of a vehicle when an abnormality occurs in the communication between ECUs.

Means for Solving the Problems

[0006] The fuel cell control system of the present invention comprises a first ECU that determines a target value for the power generated by a fuel cell mounted on a vehicle based on the power required by the vehicle, and a second ECU that receives the target value from the first ECU and controls the power generation of the fuel cell according to the target value. The second ECU sets the target value to a constant value and controls the power generation of the fuel cell when it detects an abnormality in communication with the first ECU, and the first ECU limits the power required by the vehicle based on the constant value when it detects an abnormality in communication with the second ECU. [Effects of the Invention]

[0007] According to the present invention, the vehicle's mileage can be improved when an abnormality occurs in communication between ECUs. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram showing an example of a fuel cell system. [Figure 2] Figure 2 is a sequence diagram showing an example of the operation of control system 1 when communication between the EV (Electric Vehicle)-ECU and FC-ECU is normal. [Figure 3] Figure 3 is a sequence diagram showing an example of the operation of control system 1 when communication between EV-ECU and FC-ECU is abnormal. [Modes for carrying out the invention]

[0009] (Fuel cell system configuration) Figure 1 is a configuration diagram showing an example of a fuel cell system S. The fuel cell system S is installed, for example, in a combustion battery vehicle (hereinafter referred to as "vehicle") V, which is an example of a vehicle. The fuel cell system S includes a control system 1, a fuel cell FC stack 20, an air compressor 21, an injector 22, a fuel tank 23, a boost converter 30, an inverter 31, a motor generator (MG) 32, a converter 33, a secondary battery 34 such as a lithium-ion battery, and a sensor system 4.

[0010] The air compressor 21 pumps oxidizer gas (air) to the FC stack 20. The fuel tank 23 stores hydrogen gas fuel in a pressurized state. The injector 22 supplies the hydrogen gas from the fuel tank 23 to the FC stack 20. The FC stack 20 receives the hydrogen gas and oxidizer gas and generates electricity through an electrochemical reaction between hydrogen and oxygen.

[0011] The boost converter 30 boosts the output voltage of the FC stack 20. The boost converter 30 is a multiphase DC (Direct Current) / DC converter. Each phase converter circuit includes multiple sets of reactors (not shown), an intelligent power module (IPM), and a smoothing capacitor. The inverter 31 converts the DC current input from the boost converter 30 into a three-phase AC current and supplies it to the MG 32. The MG 32 is the drive source for the vehicle V and drives the wheels (not shown) to move the vehicle V.

[0012] Converter 33 is a bidirectional DC / DC converter. Converter 33 steps down the DC voltage adjusted by the boost converter 30, or steps up the DC voltage of the secondary battery 34 to supply the output power of the secondary battery 34 to the inverter 31. The secondary battery 34 can charge and discharge the power generated by the FC stack 20.

[0013] The sensor system 4 includes various sensors. These sensors include an accelerator position sensor, a brake position sensor, a shift position sensor (not shown), and other sensors related to the status of auxiliary equipment such as an air conditioner.

[0014] Control system 1 is an example of a fuel cell control system. Control system 1 includes EV-ECU11, FC-ECU12, BAT-ECU13, and MG-ECU14. EV-ECU11, FC-ECU12, BAT-ECU13, and MG-ECU14 each have a microcontroller including a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory), and operate the CPU according to a program stored in the ROM.

[0015] EV-ECU11 and FC-ECU12 communicate with each other via CAN (Controller Area Network) through the local bus 15. EV-ECU11, FC-ECU12, and BAT-ECU13 communicate with each other via CAN through the global bus 16.

[0016] EV-ECU11 is an example of a first ECU. EV-ECU11 determines a target value for the power generated by the FC stack 20 based on the power required by the vehicle V (hereinafter referred to as required power). EV-ECU11 transmits the target value to FC-ECU12 via the local bus 15. EV-ECU11 calculates the required power based on, for example, the accelerator opening detected by the sensor system 4, and distributes it between the stored power of the secondary battery 34 and the power generated by the FC stack 20.

[0017] FC-ECU12 is an example of a second ECU. FC-ECU12 receives target values ​​from EV-ECU11 and controls the power generation of the FC stack 20 according to the target values. FC-ECU12 also controls the output (impeller rotation speed) of the air compressor 21 and the duty cycle of the drive signal of the boost converter 30 according to the target values.

[0018] The BAT-ECU 13 monitors the state of the secondary battery 34 and sets Win and Wout, which are the input / output limit values of the secondary battery 34, based on the monitoring results. Win is the upper limit value of the input power of the secondary battery 34, and Wout is the upper limit value of the output power of the secondary battery 34. The BAT-ECU 13 detects, for example, the current, voltage, and SOC (State Of Charge) of the secondary battery 34 as the state of the secondary battery 34 by using a built-in sensor.

[0019] The MG-ECU 14 controls the inverter 31 based on the torque command value of the vehicle V instructed by the EV-ECU 11. The EV-ECU 11 calculates a torque command value from, for example, map data based on the accelerator opening degree.

[0020] The EV-ECU 11 and the FC-ECU 12 transmit and receive data signals to and from each other, for example, periodically via the local bus 15. When a failure occurs in the local bus 15 (see the cross mark), the EV-ECU 11 and the FC-ECU 12 stop receiving data signals. Therefore, the EV-ECU 11 and the FC-ECU 12 detect an abnormality in the communication of the local bus 15.

[0021] When the FC-ECU 12 detects an abnormality in the communication with the EV-ECU 11, the FC-ECU 12 sets the target value of the power generation of the FC stack 20 to a constant value and controls the power generation of the FC stack 20. Therefore, the FC-ECU 12 can continue the power generation of the FC stack 20 even if it does not receive the target value from the EV-ECU 11.

[0022] When the EV-ECU 11 detects an abnormality in the communication with the FC-ECU 12, the EV-ECU 11 limits the required power based on the above constant value. The EV-ECU 11 calculates a torque command value based on the constant value and Wout of the secondary battery 34. Therefore, the output torque of the MG 32 is suppressed according to the power generation of the FC stack 20 and the output limit of the secondary battery 34. The details of the operation of the control system 1 will be described below.

[0023] (Operation of the control system) Figure 2 is a sequence diagram showing an example of the operation of control system 1 when communication between EV-ECU11 and FC-ECU12 is normal. This process is executed repeatedly, for example, at a fixed period.

[0024] First, the EV-ECU11 acquires various sensor values ​​(detected values) from the sensor system 4 (St11). Next, the EV-ECU11 calculates the required power from the sensor values ​​(St12).

[0025] Next, BAT-ECU13 detects the state of the secondary battery 34 (St31). Then, BAT-ECU13 calculates Win and Wout from the state of the secondary battery 34 (St32). BAT-ECU13 notifies EV-ECU11 of Win and Wout via the global bus 16.

[0026] The EV-ECU11 calculates the ratio for distributing the requested power to the FC stack 20 and the secondary battery 34 respectively (St13). For example, the EV-ECU11 calculates the power that the secondary battery 34 can output from Wout and allocates it to the requested power, and allocates the remaining deficit to the power generated by the FC stack 20. Next, the EV-ECU11 calculates the target value of the power generated by the FC stack 20 based on the ratio of the requested power distribution (St14). The EV-ECU11 notifies the FC-ECU12 of the target value via the local bus 15.

[0027] When FC-ECU12 receives a target value from EV-ECU11, it controls the power generation of FC stack 20 based on the target value (St21). Next, EV-ECU11 calculates a torque command value from the sensor value (St15). EV-ECU11 notifies MG-ECU14 of the torque command value. MG-ECU14 controls the output torque of MG32 according to the torque command value (St41).

[0028] Figure 3 is a sequence diagram showing an example of the operation of control system 1 when communication between EV-ECU11 and FC-ECU12 is abnormal. In Figure 3, processes common to Figure 2 are denoted by the same reference numerals, and their explanations are omitted.

[0029] First, a communication failure occurs on the local bus 15 between the EV-ECU 11 and the FC-ECU 12 (St1). Next, the EV-ECU 11 and the FC-ECU 12 each detect a communication abnormality in response to the fact that no data signal has been received from the other party for a predetermined period (St10, St20). The EV-ECU 11 and the FC-ECU 12 execute a communication standby operation (St2) in response to the detection of the abnormality. Note that the communication standby operation is repeatedly executed, for example, at a fixed period.

[0030] In the communication standby operation, the FC-ECU 1 sets the target value of the power generation of the FC stack 20 to a constant value Pc (St22). The constant value Pc is a fixed value determined in advance according to the power generation performance of the FC stack 20 and the design of the vehicle V. The FC-ECU 12 controls the power generation of the FC stack 20 with the target value being the constant value Pc (St23). As a result, since the FC stack 20 continues power generation, the driving distance of the vehicle V is extended as compared with the case of traveling only with the remaining power of the secondary battery 34.

[0031] Also, the EV-ECU 11 calculates the upper limit value of the power supplied to the MG32 based on the constant value Pc which is the target value of the power generation of the FC stack 20 (St16). The EV-ECU 11 calculates a torque command value according to the upper limit value (St17). Thereby, the power required for driving the MG32 is limited according to the constant value Pc. Thus, since the EV-ECU 11 limits the required power according to the constant value Pc, a sufficient driving distance is ensured regardless of the state of the vehicle V.

[0032] Also, the BAT-ECU 13 compares |Win| (absolute value) with the constant value Pc during the communication standby operation (St33). When |Win|≥Pc holds (No in St33), the BAT-ECU 13 detects the state of the secondary battery 34 again (St31) and calculates Win and Wout (St32). When |Win|<Pc holds (Yes in St33), the BAT-ECU 13 instructs the EV-ECU 11 and the FC-ECU 12 to stop the communication standby operation via the global bus 16.

[0033] When EV-ECU11 and FC-ECU12 receive a command to stop communication-less operation, they stop communication-less operation (St18, St24). This prevents overcharging of the secondary battery 34 by power generation from the FC stack 20.

[0034] Next, the EV-ECU11 instructs the MG-ECU14 to operate the vehicle using only the remaining power of the secondary battery 34. The MG-ECU14 controls the battery operation according to the instructions of the EV-ECU11. At this time, the MG-ECU14 controls the inverter 31 so that, for example, the output torque of the MG34 corresponds to the Wout of the secondary battery 34. The control system 1 operates in this manner.

[0035] As described above, according to control system 1, if an abnormality in communication between FC-ECU12 and EV-ECU11 is detected, FC-ECU12 controls power generation by setting the target value of the power generated by the FC stack 20 to a constant value Pc, and EV-ECU12 limits the power demanded by the vehicle V based on the constant value Pc. As a result, power generation by the FC stack 20 can continue, and the power consumption of the vehicle V is suppressed, thereby improving the driving range of the vehicle V.

[0036] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0037] V Vehicle, 1 Control system (fuel cell control system), 11 EV-ECU (first ECU), 12 FC-ECU (second ECU), 20 FC stack (fuel cell)

Claims

[Claim 1] A first ECU determines a target value for the power generated by the fuel cell installed in the vehicle based on the power required by the vehicle, The system includes a second ECU that receives the target value from the first ECU and controls the power generation of the fuel cell according to the target value, If the second ECU detects an abnormality in communication with the first ECU, it sets the target value to a constant value and controls the power generation of the fuel cell. If the first ECU detects an abnormality in communication with the second ECU, it limits the power required by the vehicle based on the constant value. Fuel cell control system.

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