JP2006223061A - Controller of fuel cell vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize the idle stop period of a fuel cell system mounted on a fuel cell vehicle. <P>SOLUTION: Based on the current-voltage characteristics and the occurrence state of flooding of a fuel cell, response speed of generation power is estimated when the fuel cell starts power generation. Based on the accumulation state of a secondary battery 16, power suppliable from the secondary battery 16 to the drive system of a fuel cell vehicle is operated. Based on the traveling state of the fuel cell vehicle, transition with time of the maximum level of power required for driving the fuel cell vehicle is estimated. Based on the response speed, the suppliable power, and transition of power, a fuel cell system determines a timing for resetting power generation from idle stop state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a fuel cell vehicle that controls an idle stop period of a fuel cell system mounted on the fuel cell vehicle.

Conventionally, as this type of technology, for example, those described in the following documents are known (see Patent Document 1). In the technique described in this document, the fuel cell is based on the speed of the fuel cell vehicle, the motor output (electric load) of the driving motor, the determination result of the on / off state of the brake, and the remaining power storage amount of the power storage device. The configuration is such that operation stop / start determination is performed. That is, the condition that the vehicle speed of the fuel cell vehicle is smaller than the predetermined speed, the output of the traveling motor or the like is smaller than the predetermined motor output, the brake is on, and the voltage between the terminals of the power storage device is larger than the predetermined voltage. When all of the above were satisfied, the execution permission of idle stop was given.
JP 2001-359204 A

  In such a conventional control device for a fuel cell vehicle, the timing of the fuel cell idle stop and start is uniquely determined by the operation state of the fuel cell vehicle and the operation state of the fuel cell system, and the fuel cell vehicle Therefore, there is a possibility that the optimum idle stop period cannot be realized.

  Accordingly, the present invention has been made in view of the above, and an object of the present invention is to provide a control device for a fuel cell vehicle that optimizes the idle stop period of the fuel cell system mounted on the fuel cell vehicle. It is to provide.

  In order to achieve the above object, the means for solving the problems of the present invention is to generate power in a fuel cell by an electrochemical reaction between a fuel gas and an oxidant gas, and to control the supply of electric power obtained by the power generation to a traveling motor. And a power storage unit that is charged with electric power obtained by the fuel cell system and regenerative electric power from the traveling motor and supplies the charged electric power to the traveling motor. In a control device for a fuel cell vehicle that is driven, the response speed of the generated power is estimated when the fuel cell starts power generation based on the current-voltage characteristics of the fuel cell and the occurrence of flooding of the fuel cell. Based on the power storage state of the power generation response estimating means and the power storage means, the dischargeable power for calculating the power that the power storage means can supply to the drive system of the fuel cell vehicle A calculating means, a driving power transition estimating means for estimating a temporal transition of a maximum value of electric power required for driving the fuel cell vehicle based on a traveling state of the fuel cell vehicle, and a power generation response estimating means; Based on the estimated response speed, the suppliable power obtained by the dischargeable power calculating means, and the power transition estimated by the drive power transition estimating means, the fuel cell system returns to the power generation from the idle stop state. And a start timing calculating means for determining the timing to perform

  According to the present invention, the idle stop is determined by determining the start timing of the fuel cell system based on the power generation response speed of the fuel cell, the drive power required by the drive system, and the power that can be supplied from the secondary battery to the drive system. The period can be optimized.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a fuel cell system including a control device for a fuel cell vehicle according to Embodiment 1 of the present invention. The system of the first embodiment shown in FIG. 1 has a fuel gas tank 1 that stores fuel gas, a pressure control valve 2 that controls the pressure of the fuel gas supplied from the fuel gas tank 1, and a pressure control valve 2 that controls the pressure. The flow path 3 for supplying the fuel gas to the fuel cell 7, the flow path for circulating the fuel gas discharged from the fuel cell 7, the ejector 4 provided at the junction of the flow path 3, and the fuel cell 7 with the oxidant The compressor 5 for supplying gas air, the flow path 6 for supplying the air supplied from the compressor 5 to the fuel cell 7, the fuel cell 7 for generating power using the fuel gas and air, and the fuel cell 7 discharged. An exhaust pipe 9 that exhausts air and a pressure control valve 8 that controls the pressure of air exhausted from the exhaust pipe 9 are provided.

  On the other hand, the control system of the fuel cell system includes an air flow meter 10 for detecting the flow rate of air flowing in the flow path 6, an ammeter 11 for detecting the output current of the fuel cell 7, and the output voltage of the fuel cell 7. By controlling the voltmeter 12 to be detected, the output controller 13 for controlling the output of the fuel cell 7, the temperature sensor 14 for detecting the temperature of the fuel cell 7, the pressure control valve 2 and the compressor 5, the fuel cell 7 And a controller 15 for controlling the pressure and flow rate of the fuel gas and air to be supplied.

  The controller 15 functions as a control center for controlling the operation of the system, and includes, for example, a microcomputer having resources such as a CPU, a storage device, and an input / output device necessary for a computer that controls various operation processes based on a program. It is realized by. The controller 15 reads signals from the air flow meter 10, ammeter 11, voltmeter 12, and temperature sensor 14 in this system, and based on the read various signals and control logic (program) stored in advance in the system 15 A command is sent to each of these components, and all operations necessary for operation / stop of the system including the control operation in the idle stop period described below are managed and controlled. Therefore, the controller 15 is configured by a microcomputer or the like, and has a function of realizing the means shown in FIGS. 3 to 6 for executing the processing procedure shown in FIG. 2 described later.

  A drive motor control means 17 is connected to the output controller 13 that controls the output of the fuel cell 7, and the electric power extracted from the fuel cell 7 is supplied to the drive travel motor of the fuel cell vehicle via the drive motor control means 17. Is done. Further, a chargeable / dischargeable secondary battery 16 is connected in parallel with the drive motor control means 17, and the electric power taken out from the fuel cell 7 through the output controller 13 and the regenerative power of the drive travel motor are the secondary battery 16. The power stored in the secondary battery 16 or stored in the secondary battery 16 can be supplied to the drive travel motor via the drive motor control means 17.

  Next, the control procedure of the first embodiment will be described with reference to the flowchart of FIG.

  The control procedure shown in FIG. 2 is executed every predetermined time, for example, every 10 [msec], and the power generation of the fuel cell system shown in FIG. 1 is stopped and the predetermined actuator is also stopped (hereinafter referred to as idle stop). The processing is effective only when returning from (calling).

  In FIG. 2, it is first determined whether or not there is a return request from idle stop (step S101). If there is a return request, the processing of steps S102 to S104 described below is executed, while the return request is received. If not, the control process ends.

  If there is a request for returning from the idle stop, it is determined whether or not the maximum torque value of the drive motor can be limited when returning from the idle stop (step S102). Thereafter, when limiting the torque of the drive motor, calculation of the torque limit value and change of the torque response target are set (step S103). Subsequently, the power generation start timing of the fuel cell system after the idle stop return request is determined (step S104).

  Next, means for realizing the control procedure shown in the flowchart of FIG. 2 will be described in detail with reference to the block diagrams of FIGS.

  FIG. 3 is a block diagram showing means for executing steps S102 and S103 of FIG. 2. Is it possible to estimate the vehicle state by means shown in FIG. 3 to limit the maximum torque value and speed up the torque response? Determine whether or not.

  In FIG. 3, the means for executing the control procedure includes a gradient detection means 31, an accelerator opening speed detection means 32, a vehicle gross weight detection means 33, a traffic jam determination means 34, and a determination calculation means 35.

  The gradient detecting means 31 is a functional means for detecting the road surface gradient of the road on which the vehicle is going to travel, and may calculate the road surface gradient from the position information and map information from the satellite or detect the inclination in the vehicle front-rear direction. Means to do this may be provided.

  The accelerator opening speed detecting means 32 is a functional means for detecting the opening speed of the accelerator pedal operated by the driver. The accelerator opening speed detecting means 32 is a means for detecting the accelerator opening, and a change per unit time in the accelerator opening information obtained by the detecting means. It is implement | achieved by having a means to detect quantity.

  The vehicle total weight detection means 33 is a means for detecting the total weight of the vehicle, and estimates the total vehicle weight that changes depending on the number of passengers and the loading state. As an estimation method, before determining whether or not the maximum value of the torque may be limited, the driving force and the vehicle acceleration are calculated in a state in which it is determined that the road is a flat road by means having the same function as the gradient detecting means 31. The vehicle weight is detected from the detection result. Alternatively, a means for detecting the length of the coil spring of the suspension part of the vehicle is provided, the vehicle is stopped, the key is inserted into the key cylinder, the fuel cell system is activated, and all the doors are closed, that is, a person Alternatively, it is possible to detect a state assumed to have been loaded and ready to start running as a length when loaded, and to estimate the vehicle weight from the length and the spring constant of the coil spring.

  The traffic jam judging means 34 is a functional means for judging whether or not the traffic state of the travel road is jammed. The traffic jam judging means 34 is provided with means for detecting an average vehicle speed before a predetermined time, and whether the detected speed is equal to or less than a predetermined value. If it is below a predetermined value, it is determined that the vehicle is traveling on a congested road. Alternatively, traffic from outside such as VICS of an information communication system that sends traffic traffic information such as traffic jams and traffic regulations edited and processed at the Road Traffic Information Center in real time and displays them in characters and figures on in-vehicle devices such as car navigation Information may be received and determined based on it.

  The determination calculation means 35 aggregates the information obtained by the gradient detection means 31, the accelerator opening speed detection means 32, the vehicle total weight detection means 33, and the traffic congestion determination means 34, and limits the torque maximum value of the drive travel motor. The permission determination as to whether or not it is acceptable and the limit value are calculated.

  Specifically, when it is determined that the vehicle is on the climb slope, the maximum torque limit is not permitted and the climb performance is maintained. If the accelerator opening speed is smaller than a predetermined value, it is determined that the driver does not request immediate acceleration, and the maximum torque value is allowed to be limited. At the same time, the torque response is normal (the drive torque is limited). If not, make it faster and reduce the decrease in acceleration feeling. In addition, it is determined whether or not the total vehicle weight is equal to or greater than a predetermined value. If the total vehicle weight is equal to or greater than a predetermined value, the limitation on the maximum torque value is not permitted and the acceleration performance is maintained. If it is determined that the vehicle is traveling in a traffic jam, the maximum torque value is allowed to be restricted, and at the same time, the torque response is made faster than usual to reduce the decrease in acceleration feeling.

  The torque limit value may be calculated by multiplying the value before the limit by a predetermined coefficient, for example, about 70%, or by adding or subtracting the accelerator opening speed delay, or the vehicle total You may obtain | require using the coefficient which changes based on the lightness adjustment of a weight.

  In addition, when it is determined that the vehicle is on an uphill slope, the torque maximum value may not be limited, and only the torque response may be made faster than usual. Thereby, the effect that reduction of the rollback feeling which may occur by slope start etc. can be anticipated is acquired.

  FIG. 4 is a block diagram showing means for executing step S104 of FIG. 2, and shows means for determining the start timing of the fuel cell system. In FIG. 4, means for executing the control procedure includes IV estimation means 41, flooding generation estimation means 42, power generation response estimation means 43, dischargeable power calculation means 44, drive power transition estimation means 45, and start timing calculation means 46. Configured.

  The IV estimation means 41 is a means for estimating the current-voltage characteristics of the fuel cell 7, detects the temperature representative of the fuel cell 7 by the temperature sensor 14, and obtains the current-voltage characteristics for each temperature calculated in advance through experiments or the like. By referencing, the current-voltage characteristic at that time is estimated.

  The flooding occurrence estimation means 42 is a means for estimating whether or not there is a possibility that flooding has occurred in the fuel cell 7. When flooding occurs in the fuel cell 7 and the water blocks a part of the gas flow path, the reaction area is reduced, and the voltage may be partially reduced. As a result, the voltage of the entire fuel cell may be less than the expected value.

  Therefore, in order to obtain a desired output from the fuel cell 7, it is necessary to draw a larger current value than the current assumed from the current-voltage characteristics estimated by the IV estimation means 41, and the air flow rate is increased accordingly. As a result, the output response of the fuel cell 7 requires more time than when no flooding occurs. Therefore, it is estimated whether there is a possibility of flooding inside the fuel cell 7, and the estimated value of the response speed of the fuel cell system is corrected according to the result.

  As a flooding estimation method, a value representative of the temperature of the fuel cell 7, for example, a temperature sensor that detects the outlet temperature of the cooling water is provided, and the amount of change per unit time of the cooling water temperature measured by the temperature sensor is previously determined. It may be determined that flooding is likely to occur when it is determined that the threshold value has dropped beyond a set threshold. Alternatively, means for detecting the voltage of each cell constituting the fuel cell 7 and means for determining variation in the detected cell voltage are provided, and the cell voltage indicating the minimum value is set in advance from the voltages of the other cells. If it is determined that the voltage is lower than the predetermined value and the voltages of other cells are within a predetermined value set in advance, it may be determined that flooding has occurred.

  The power generation response estimation unit 43 estimates a response speed related to power generation of the fuel cell 7 based on the current-voltage characteristics estimated by the IV estimation unit 41 and the flooding occurrence state estimated by the flooding generation estimation unit 42. . That is, when returning from the idle stop, it is estimated how much power the fuel cell 7 can generate with respect to the elapsed time from the start of return. The power generation response estimation means 43 is constituted by the means shown in FIG.

  In FIG. 5, the power generation response estimation unit 43 includes an IV correction unit 51, an air system response calculation unit 52, a current-supply air flow rate characteristic calculation unit 53, and a power generation response estimation unit 54.

  The IV correction unit 51 corrects the current-voltage characteristic estimated by the IV estimation unit 41 shown in FIG. 4 using the flooding estimated value determined by the flooding generation estimation unit 42 shown in FIG. The content of the correction may be to reduce the voltage value of the current-voltage characteristic by a predetermined value when flooding is expected. Or you may reduce a voltage value according to the deviation width of the voltage value of the cell which shows the minimum voltage, and the average value of another cell.

  The air system response calculation means 52 calculates and outputs the response of the air supply system, that is, how long the amount of air supplied to the fuel cell 7 can be increased. The air response information may be calculated in advance through experiments or the like, or the mass flow rate may be corrected from the intake air temperature, the atmospheric pressure, or the like during traveling.

  The current-supply air flow rate characteristic calculating means 53 calculates and stores the relationship between the power generation current of the fuel cell 7 and the supply air flow rate. The relationship between the power generation current of the fuel cell 7 and the supply air flow rate is calculated through experiments and desk studies.

  The power generation response estimation unit 54 is based on the air flow rate characteristic obtained by the air system response calculation unit 52 and the relationship between the power generation current and the supply air flow rate stored in the current-supply air flow rate characteristic calculation unit 53. The rising response characteristic of the generated current when returning from the idle stop is obtained. The power generation response estimation unit 54 multiplies the obtained rise response characteristic of the generated current by the voltage characteristic corrected by the IV correction unit 51 to obtain the response characteristic of the generated power of the fuel cell 7.

  Returning to FIG. 5, the dischargeable power calculation means 44 is a means having a function of estimating and calculating how much power can be discharged from the secondary battery 16, for example, recognizing the storage state of the power storage device It consists of a battery manager etc.

  The drive power transition estimation means 45 is a means for estimating the time change of the maximum power value requested from the drive system, and is configured as shown in FIG. In FIG. 6, the drive power transition estimation means 45 includes a gradient detection means 61, a vehicle total weight detection means 62, a running resistance calculation means 63, a vehicle speed transition calculation means 64, and a drive power transition calculation means 65. .

  The gradient detection means 61 determines the road condition on which the vehicle is traveling, estimates the road gradient based on the position information from the satellite and the previously recorded map information, represented by the car navigation system, and 3 is configured similarly to the gradient detecting means 31 shown in FIG.

  The vehicle total weight detecting means 62 may calculate the total weight of the vehicle from the relationship between the generated torque and the acceleration during traveling, or when detecting that the suspension spring length is stopped or the acceleration is low. The measurement result may be calculated by replacing the measurement result with the total vehicle weight. Alternatively, the empty vehicle weight and the weight of about one passenger may be stored in advance as fixed values and used.

  The running resistance calculation means 63 includes vehicle specifications such as road gradient information detected by the gradient detection means 61, vehicle total weight information detected by the vehicle total weight detection means 62, and the air resistance coefficient and front projection area of the vehicle. Based on this, the running resistance of the vehicle is calculated.

  The vehicle speed transition calculating means 64 calculates the acceleration of the vehicle based on the running resistance obtained by the running resistance calculating means 63 and the maximum torque limited value determined by the determination calculating means 35 shown in FIG. Further, the transition of the vehicle speed is estimated by integrating the acceleration.

  The driving power transition calculating means 65 multiplies the vehicle speed transition obtained by the vehicle speed transition calculating means 64 by the maximum torque-limited value determined by the determination calculating means 35 shown in FIG. The transition of the maximum value of the power required for driving is obtained.

  Returning to FIG. 4, the start timing calculation means 46 is based on the information obtained by the power generation response estimation means 43, the dischargeable power calculation means 44, and the drive power transition estimation means 45 described above, and the torque limit value of the drive travel motor. And a torque response value is calculated.

  When the vehicle starts from the idle stop state, the secondary battery 16 supplies power to the drive system until the power generation of the fuel cell system starts up while the power consumed by the drive system increases. That is, if the power supply from the fuel cell 7 is not started immediately before the power consumed by the drive system exceeds the power that can be supplied by the secondary battery 16, the power consumption of the drive system can be increased beyond that value thereafter. Disappear. In this case, there is a possibility that the change in the driving force may be uncomfortable.

  Therefore, the time response of the power generation output from the fuel cell system estimated by the power generation response estimation means 43, the maximum discharge power of the secondary battery 16 calculated by the dischargeable power calculation means 44, and the drive power transition estimation means 45 are estimated. Power generation from the fuel cell system is started within a time period in which the required power required by the drive system does not exceed the maximum dischargeable power of the secondary battery 16 based on the transition estimation result of the power required by the drive system. Thus, the maximum torque limit value of the drive system and the start start timing of the fuel cell system are calculated.

  As described above, when returning from the idle stop, as shown in FIG. 7A, the maximum value of the generated torque of the drive motor is limited, and at the same time, the control for increasing the response speed of the torque is performed compared to the normal time. Thus, as shown in FIG. 6B, the increase rate of the electric power (required output) required when the fuel cell system returns from the idle stop can be reduced without impairing the acceleration feeling of the vehicle. As a result, as shown in FIG. 7B, the power generation timing of the fuel cell system can be delayed as compared with the conventional case, and the idle stop period can be extended.

  Further, by limiting the maximum value of the generated torque based on the traveling state of the vehicle, the influence on the driving performance of the vehicle can be reduced as much as possible.

  Furthermore, by determining the idle stop return timing of the fuel cell system based on the power generation response speed of the fuel cell 7, the drive power required by the drive system, and the power that can be supplied by the secondary battery 16, it is possible to optimize the idle stop period. Can be realized.

It is a figure which shows the structure of the fuel cell system containing the control apparatus of the fuel cell vehicle which concerns on Example 1 of this invention. It is a flowchart which shows the procedure of operation | movement of Example 1 of this invention. It is a figure which shows the means to implement | achieve one operation | movement procedure of Example 1 of this invention. It is a figure which shows the means to determine the starting timing after the idle stop of a fuel cell system. It is a figure which shows the structure of the electric power generation response estimation means shown in FIG. It is a figure which shows the structure of the drive electric power transition estimation means shown in FIG. It is a figure which shows the time change of the torque of a motor, a fuel cell output, the request | requirement output of a fuel cell, and a secondary battery output.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel gas tank 2 ... Pressure control valve 3, 6 ... Flow path 4 ... Ejector 5 ... Compressor 7 ... Fuel cell 8 ... Pressure control valve 9 ... Exhaust pipe 10 ... Air flow meter 11 ... Ammeter 12 ... Voltmeter 13 ... Output Controller 14 ... Temperature sensor 15 ... Controller 16 ... Secondary battery 17 ... Drive motor control means 31, 61 ... Gradient detection means 32 ... Accelerator opening speed detection means 33, 62 ... Vehicle gross weight detection means 34 ... Congestion judgment means 35 ... Determination calculation means 41 ... IV estimation means 42 ... Flooding occurrence estimation means 43 ... Power generation response estimation means 44 ... Dischargeable power calculation means 45 ... Drive power transition estimation means 46 ... Start timing calculation means 51 ... IV correction means 52 ... Air system response Calculation means 53 ... Supply air flow rate characteristic calculation means 54 ... Power generation response estimation means 63 ... Travel resistance calculation means 64 ... Vehicle speed transition calculation Stage 65 ... driving power transition operation means

Claims (3)

A fuel cell system that generates electric power in a fuel cell by an electrochemical reaction between a fuel gas and an oxidant gas, and supplies and controls the electric power obtained by the electric power generation to a traveling motor, the electric power obtained by the fuel cell system, and the traveling In a control device for a fuel cell vehicle, which is charged with regenerative power from a motor for driving, and includes a power storage means for supplying the charged power to the driving motor, and is driven by the driving motor.
Based on the current-voltage characteristics of the fuel cell and the occurrence state of flooding of the fuel cell, when the fuel cell starts power generation, power generation response estimation means for estimating the response speed of the generated power;
Dischargeable power calculating means for calculating the power that the power storage means can supply to the drive system of the fuel cell vehicle based on the power storage state of the power storage means;
Driving power transition estimating means for estimating a temporal transition of the maximum value of power required for driving the fuel cell vehicle based on the traveling state of the fuel cell vehicle;
The fuel cell system is idle based on the response speed estimated by the power generation response estimating means, the suppliable power obtained by the dischargeable power calculating means, and the power transition estimated by the drive power transition estimating means. A control apparatus for a fuel cell vehicle, comprising start timing calculation means for determining a timing for returning power generation from the stop state. When the maximum value of the drive torque generated by the travel motor is selectively limited and the drive torque is not limited when the fuel cell system returns to the power generation from the idle stop state. Compared with torque calculation means to speed up response characteristics of drive torque,
2. The control apparatus for a fuel cell vehicle according to claim 1, wherein the start timing calculating means delays the timing for returning the power generation of the fuel cell as compared with the case where the drive torque is not limited. 3. The torque calculation means includes at least one of a road gradient on which the fuel cell vehicle is traveling, a traffic state in which the fuel cell vehicle is traveling, an opening speed of an accelerator pedal operated by a driver, and a mass of the fuel cell vehicle. 3. The control apparatus for a fuel cell vehicle according to claim 2, wherein the driving torque generated by the travel motor is selectively limited based on the control.

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