JP2006020468A - Control unit for fuel cell vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel performance by stopping power generation of a fuel cell during regenerative braking, and to supply a sufficient drive power during re-acceleration. <P>SOLUTION: A brake computer 20 uses both the regenerative braking by a motor and a frictional braking by a friction braking apparatus to execute braking control. A travelling control system computer 10, the brake computer 20 and a fuel cell computer 103 cooperate with each other to put the fuel cell 11 into a state from which power can be taken out, before the regenerative braking is switched to the friction braking during braking a vehicle, enabling a sufficient drive power to be supplied during re-acceleration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a fuel cell vehicle that performs regenerative braking by a vehicle drive motor.

  In a fuel cell, a fuel gas such as hydrogen gas and an oxidizing gas containing oxygen are electrochemically reacted through an electrolyte, and electric energy is directly taken out between electrodes provided on both surfaces of the electrolyte. In particular, a polymer electrolyte fuel cell using a polymer electrolyte has attracted attention as a power source for electric vehicles because of its low operating temperature and easy handling. That is, a fuel cell vehicle is equipped with a hydrogen storage device such as a high-pressure hydrogen tank, a liquid hydrogen tank, or a hydrogen storage alloy tank in the vehicle, and reacts by supplying hydrogen supplied therefrom and air containing oxygen to the fuel cell. This is the ultimate clean vehicle that drives the motor connected to the drive wheels with the electric energy extracted from the fuel cell, and the only exhaust material is water.

  Normally, hybrid vehicles and fuel cell vehicles are used for the next start or acceleration by converting the kinetic energy of the vehicle into electric power by regenerative braking and storing it in a secondary battery. During this regenerative braking, in order to improve the fuel efficiency even a little, it is well known that the power generation of the engine or fuel cell is stopped according to the state of charge of the secondary battery (for example, Patent Documents 1 to 3). .

On the other hand, in the low vehicle speed range, the response speed of regenerative braking is slow to perform delicate braking according to the stroke of the brake pedal. Therefore, in the region below the predetermined vehicle speed, braking by a friction braking device using mechanical friction force is performed. Need to be implemented.
JP 2001-245405 A (5th page, FIG. 6) JP 2002-135903 A (second page, FIG. 10) JP-A-11-289605 (5th page, FIG. 1)

  However, when switching from regenerative braking to friction braking, regenerative power is not supplied and the secondary battery is discharged, and the amount of charge of the secondary battery continues to decrease. Moreover, in order to start a fuel cell system, the start time much longer than the response time which stops regenerative braking is required.

  During the start-up of the fuel cell, power is taken out from the secondary battery, and there is a problem that the driving power is insufficient at the time of reacceleration or the storage capacity of the secondary battery is insufficient.

  In order to solve the above-described problems, the present invention provides a fuel cell that generates power by receiving supply of a fuel gas containing hydrogen and an oxidant gas containing oxygen, a rechargeable secondary battery, the fuel cell, and the secondary battery. A vehicle drive motor capable of driving the vehicle with electric power supplied from at least one of them, and performing regenerative braking that converts rotational energy into electrical energy during vehicle braking, and a friction braking device that brakes the vehicle with frictional force; Before the transition from the braking state by the regenerative braking to the braking state by only the friction braking device, the braking control means that can use both the regenerative braking by the vehicle drive motor and the braking by the friction braking device during vehicle braking, And a fuel cell control means for controlling the fuel cell to a state where electric power can be taken out. .

  According to the present invention, when the generated power is unnecessary, the fuel cell system is stopped to improve the fuel efficiency, and the power can be supplied from the fuel cell immediately according to the demand. A fuel cell vehicle having driving performance can be provided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a control system of a vehicle equipped with a control device for a fuel cell vehicle according to the present invention, and FIG. 2 is a schematic configuration diagram showing a braking system and a drive system of the vehicle.

  First, a configuration of a fuel cell vehicle to which the present invention is applied will be described with reference to FIG. This fuel cell vehicle has a motor 12 that also performs regenerative braking as a vehicle drive source, and electric power to the motor 12 is supplied to the motor via an inverter 15 from at least one of the fuel cell 11 and a battery 16 that is a secondary battery. The The driving force of the motor 12 is transmitted to the front wheels FR and FL which are driving wheels via the differential gear 17.

  The motor 12 is, for example, an AC synchronous type, and the rotation speed is controlled by the three-phase AC frequency control supplied from the inverter 15. The inverter 15 performs control to rectify AC power generated by the motor 12 and charge the battery 16 or consume it in the fuel cell vehicle during regenerative braking.

  On the other hand, each wheel FR, FL, RR, RL is provided with a hydraulic brake 23 which is a friction braking device. A brake hydraulic pressure source 21 including an electric motor and an accumulator and a hydraulic pressure adjusting unit 22 that adjusts the hydraulic pressure supplied to each hydraulic brake 23 based on the hydraulic pressure of the brake hydraulic pressure source 21 are provided. ing.

  A control apparatus for a fuel cell vehicle according to the present invention includes a brake computer 20 and a travel control system computer (ECU) 10 shown in FIG. 1, a motor ECU 101, a battery ECU 102, and a fuel cell ECU 103.

  The brake computer 20 that controls the hydraulic brake 23 controls the brake hydraulic pressure source 21 and the hydraulic pressure adjustment unit 22, and is supplied with an output of a brake sensor 30 that detects an operation amount of a brake pedal (not shown). .

  The travel control computer 10 mainly controls the drive system, and includes a vehicle speed sensor 31 that detects the vehicle speed V, an accelerator sensor 32 that detects the opening of an accelerator pedal (not shown), and a longitudinal acceleration sensor that detects longitudinal acceleration of the vehicle. 33 output signals are supplied. In addition, the traveling computer 10 controls the motor ECU 101, the battery ECU 102, and the fuel cell ECU 103, shares information necessary for control through communication with the brake computer 20, and performs braking control in cooperation.

  The motor ECU 101 controls the inverter 15 to control the driving force and regenerative braking force of the motor 12.

  The battery ECU 102 monitors the state of charge (SOC) of the battery 16 and controls charging / discharging of the battery 16 based on the SOC.

  The fuel cell ECU 103 controls the start, stop, and operation state of the fuel cell 11.

  Next, the operation at the time of braking of the fuel cell vehicle will be described. First, when a brake pedal (not shown) is depressed, an operation amount of the brake pedal is supplied from the brake sensor 30 to the brake computer 20. The brake computer 20 makes a regenerative braking request to the travel control system computer 10.

  In response to this regenerative braking request, the travel control computer 10 controls the inverter 15 via the motor ECU 101 to control the motor 12 with the rotational force of the drive wheels FL and FR connected via the differential gear 17. Electricity is generated by driving, and the battery 16 is charged with the obtained electric power.

  During power generation by regenerative braking, a braking force for braking the vehicle is obtained by resistance to rotation of the motor 12. When the braking force is insufficient for the required braking force calculated from the output signal of the brake sensor 30, the brake computer 20 operates the hydraulic pressure adjusting unit 22 to adjust the hydraulic pressure supplied to each brake 23. Braking is performed by adjusting the friction braking force.

  FIG. 3 is a general flowchart of this regenerative cooperative control.

  This control is repeatedly executed at a predetermined timing after the vehicle brake computer 20 is turned on.

  First, in step S1, the brake computer 20 and the travel control computer 10 read the vehicle state quantities. The vehicle state quantity includes a brake operation amount sent from the brake sensor 30, a vehicle speed V sent from the vehicle speed sensor 31, an accelerator opening degree sent from the accelerator sensor 32, a longitudinal acceleration G of the vehicle sent from the longitudinal acceleration sensor 33, and the like. is there.

  In step S2, the brake computer 20 calculates a target deceleration (EBA (t)) from the obtained vehicle state quantity.

  Next, in step S <b> 3, the battery ECU 102 determines whether the battery 16 is fully charged based on the state of charge of the battery 16. When the battery 16 is not fully charged, the process proceeds to step S4, the brake computer 20 sends a regenerative braking request to the traveling control system computer 10, and the traveling control system computer 10 obtains the necessary deceleration. The inverter 15 is controlled via the ECU 101 to activate the regenerative brake. That is, by making the motor 12 function as a generator, the kinetic energy of the vehicle is recovered as electric power, and the battery 16 is charged.

  On the other hand, when the battery 16 is fully charged as determined in step S3, the process proceeds to step S5, where the brake computer 20 controls the hydraulic pressure adjusting unit 22 to control the braking force applied by each hydraulic brake 23, Get the necessary deceleration.

  Next, a basic configuration of the fuel cell 11 which is a drive source of the fuel cell vehicle will be described with reference to FIG.

  The fuel cell 11 includes an anode (hydrogen electrode) 11a and a cathode (air electrode) 11b to which hydrogen and air humidified by a humidifier (not shown) are respectively supplied, and directly generates electric power by an electrochemical reaction of these reaction gases. It is.

  The air is pressurized from the atmosphere by the compressor 200 and humidified by an air humidifier (not shown), and then supplied to the cathode 11b of the fuel cell. Unused air at the cathode 11b is discharged from the cathode pressure adjustment valve 205 to the atmosphere. The

  The flow rate and pressure of air supplied to the cathode 11b of the fuel cell are controlled by the rotational speed of the compressor 200 and the opening of the cathode pressure adjustment valve 205.

  The compressor 200 is driven by a motor (not shown), and the fuel cell computer 103 refers to the motor rotation speed and controls the motor so that the motor reaches the target rotation speed.

  Further, hydrogen is humidified by a hydrogen humidifier (not shown) from a hydrogen reservoir 201 filled with hydrogen at a high pressure via an anode pressure adjusting valve 201 and an ejector 203, and then supplied to the anode 11a of the fuel cell. Unused hydrogen in the fuel cell is circulated by the ejector 203 to the anode 11a of the fuel cell.

  The pressure of hydrogen supplied to the anode 11 a of the fuel cell is controlled by the opening degree of the anode pressure adjustment valve 202. The fuel cell computer 103 controls the anode pressure adjustment valve 202 so that the pressure of hydrogen supplied to the anode 11a of the fuel cell becomes a target pressure.

  The hydrogen purge valve 204 is controlled by the fuel cell computer 103 in accordance with the state of the fuel cell, thereby preventing output decrease and efficiency decrease due to water in the fuel cell, that is, air leakage from the cathode 11b to the anode 11a. It is intended for use.

  The fuel cell computer 103 controls the start or stop of the supply of hydrogen and air supplied to the fuel cell 11 in response to a request for starting or stopping the fuel cell from the travel control system computer 10.

  Next, a control apparatus for a fuel cell vehicle in Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 5 is a time chart showing, in time series, the situation when switching from regenerative braking to hydraulic braking during regenerative coordination.

  In FIG. 5A, it is assumed that the driver suddenly steps on the brake pedal and the pedal stroke rises. However, as shown in FIG. 5C, the rise of torque due to regenerative braking (the driving torque is indicated by + and the braking torque is indicated by-) is slow, so that friction braking is performed at the initial stage of braking as shown in FIG. The braking hydraulic pressure supplied to the device is temporarily increased to obtain a braking response corresponding to the brake pedal operation. Next, in response to the rise of the regenerative braking torque, the brake fluid pressure is reduced so as to reduce the friction braking torque. After that, the braking state continues only with the regenerative braking torque, but when the vehicle speed shown in FIG. 5 (b) reaches the hydraulic braking intervention switching vehicle speed (for example, 20 [km / h]), the regenerative braking torque is increased while increasing the braking hydraulic pressure. Reduce and switch smoothly from regenerative braking to friction braking. When the vehicle speed becomes equal to or lower than the regeneration cooperation end vehicle speed (for example, 10 [km / h]), the entire braking torque is controlled to be the friction braking torque. As a result, high brake response characteristics at low vehicle speeds are obtained.

  FIG. 6 is a flowchart showing the control contents of the control device for the fuel cell vehicle in the first embodiment.

  First, at step 11 (hereinafter step is abbreviated as S), the traveling control computer 10 reads the vehicle speed V detected by the vehicle speed sensor 31. Next, in S12, the traveling control computer 10 determines whether or not the vehicle speed V is lower than the set vehicle speed V0. Here, in the time chart of FIG. 5, the set vehicle speed V0 is a vehicle speed that is higher than the hydraulic braking intervention switching vehicle speed (for example, 20 [km / h]) that is the vehicle speed at which switching from regenerative braking to friction braking is started.

  If the vehicle speed V is smaller than the set vehicle speed V0 as determined in S12, the traveling control system computer 10 outputs a fuel cell system activation request signal to the fuel cell computer 103 in S13. The fuel cell computer 103 that has received the activation request signal activates the fuel cell system.

  If it is determined in S12 that the vehicle speed V is equal to or higher than the set vehicle speed V0, a fuel cell system stop request signal is output from the traveling control system computer 10 to the fuel cell computer 103 in S14. The fuel cell computer 103 that has received the fuel cell system stop request signal stops the operation if the fuel cell system is operating, and does nothing if the fuel cell system is stopped.

  Next, in S15, the traveling control computer 10 determines whether or not the vehicle speed V is lower than the hydraulic braking intervention switching vehicle speed V1 (20 [km / h] in the example of FIG. 5). If it is determined in S15 that the vehicle speed V is lower than the hydraulic braking intervention switching vehicle speed V1, the process proceeds to S16, and the traveling control system computer 10 starts hydraulic braking intervention switching (replacement) for the brake computer 20 and the motor ECU 101. And return.

  When the brake computer 20 receives an instruction to start the hydraulic braking intervention switching (replacement), it cooperates with the motor ECU 101 to gradually increase the braking hydraulic pressure and to brake each wheel (23FL, 23FR, 23RL, 23RR). Control is performed so that the friction braking torque is increased and the regenerative braking torque by the motor 12 is decreased.

  If it is determined in S15 that the vehicle speed V is equal to or higher than the hydraulic braking intervention switching vehicle speed V1, the process proceeds to S17, and the traveling control system computer 10 returns to a standby state for hydraulic braking intervention switching (replacement).

  According to the embodiment described above, when the generated power is unnecessary, the fuel cell system is stopped to improve the fuel efficiency, and the power can be supplied from the fuel cell immediately according to the demand. It is possible to provide a fuel cell vehicle having high driving performance without the need to do so.

  Next, a second embodiment of the control apparatus for a fuel cell vehicle according to the present invention will be described. The configuration of the fuel cell vehicle to which the control device of the second embodiment is applied and the overall configuration of the control device are the same as those of the first embodiment described with reference to FIGS. .

  The feature of the second embodiment is that the time until the start of switching from the regenerative braking state to the friction braking state is compared with the start time of the fuel cell system, and it is determined that the time until the start of switching is shorter than the start time. The point is that start control of the fuel cell system is started.

  Next, Embodiment 2 will be described with reference to the control flowchart of FIG.

  First, in S21, the traveling control computer 10 reads the vehicle speed V detected by the vehicle speed sensor 31 and the longitudinal acceleration G detected by the longitudinal acceleration sensor 33. Note that the longitudinal acceleration sensor 33 is not provided, and the time differential value of the vehicle speed V detected by the vehicle speed sensor 31 may be used as the longitudinal acceleration G. Next, in S22, the travel control system computer 10 determines the hydraulic braking intervention switching (replacement) control start vehicle speed V1 from the regenerative braking state to the friction braking state based on the values of the vehicle speed V and the longitudinal acceleration G (in the example of FIG. 5, 20 [km / h]) is calculated as required time T1. Next, in S23, the traveling control system computer 10 determines whether or not T1 is shorter than the required startup time Ts, which is the time required to start the fuel cell system.

  If it is determined in S23 that T1 is shorter than the required startup time Ts, the travel control system computer 10 transmits a fuel cell system startup request signal to the fuel cell computer 103 in S24. The fuel cell computer 103 that has received the activation request signal activates the fuel cell system. If the fuel cell system is already activated, nothing is done.

  If it is determined in S23 that T1 is equal to or longer than the required startup time Ts, in S25, the traveling control computer 10 transmits a fuel cell system stop request signal to the fuel cell computer 103. The fuel cell computer 103 that has received the stop request signal stops the fuel cell system. If it has already stopped, the fuel cell computer 103 ends without doing anything.

  According to the second embodiment described above, since the fuel cell system is restarted at an appropriate timing, the state where the power of the fuel cell cannot be obtained can be suppressed in a short time, and the shortage of power can be prevented. .

  Next, a third embodiment of the control apparatus for a fuel cell vehicle according to the present invention will be described. The configuration of the fuel cell vehicle to which the control device of the third embodiment is applied and the overall configuration of the control device are the same as those of the first embodiment described with reference to FIGS. .

  The feature of the third embodiment is that, in the second embodiment, when the state of charge of the battery 16 exceeds a predetermined value, the startup time of the fuel cell system is longer than the time until the start of switching from the regenerative braking state to the friction braking state. When the fuel cell system continues to generate power in a long time, while the start time of the fuel cell system is shorter than the time from the start of switching from the regenerative braking state to the friction braking state, the fuel cell power generation is stopped. is there.

  Next, Embodiment 3 will be described with reference to the control flowchart of FIG.

  First, in S <b> 31, the travel control computer 10 reads the vehicle speed V detected by the vehicle speed sensor 31 and the longitudinal acceleration G detected by the longitudinal acceleration sensor 33. Note that the longitudinal acceleration sensor 33 is not provided, and the time differential value of the vehicle speed V detected by the vehicle speed sensor 31 may be used as the longitudinal acceleration G. Next, in S32, the traveling control computer 10 determines the hydraulic braking intervention switching (replacement) control start vehicle speed V1 from the regenerative braking state to the friction braking state based on the values of the vehicle speed V and the longitudinal acceleration G (in the example of FIG. 5, 20 [km / h]) is calculated as required time T1. Next, in S33, the traveling control computer 10 determines whether or not T1 is shorter than the required startup time Ts, which is the time required to start the fuel cell system.

  If it is determined in S33 that T1 is shorter than the required startup time Ts, the travel control system computer 10 transmits a startup request signal for the fuel cell system to the fuel cell computer 103 in S34. The fuel cell computer 103 that has received the activation request signal activates the fuel cell system. If the fuel cell system is already activated, nothing is done. If it is determined in S33 that T1 is equal to or longer than the required startup time Ts, in S35, the traveling control computer 10 reads the state of charge (SOC) of the battery 16 detected by the battery ECU 102. Next, the traveling control computer 10 determines in S36 whether or not the read SOC exceeds a predetermined charged state (SOC_TOP). Here, the predetermined charging state is a charging state in which transient charging can be performed slightly less than full charging, for example, a charging state of SOC = 95 [%].

  If it is determined in S36 that the SOC does not exceed SOC_TOP, it is determined that the battery 16 can be charged with surplus power, and the control of the traveling control computer 10 proceeds to S34.

  If it is determined in S36 that the SOC exceeds SOC_TOP, the control of the traveling control computer 10 proceeds to S37 in order to stop the charging of the battery 16, and transmits a fuel cell system stop request signal to the fuel cell computer 103. . The fuel cell computer 103 that has received the stop request signal stops the fuel cell system. If it has already stopped, the fuel cell computer 103 ends without doing anything.

  According to the third embodiment described above, since the power generation of the fuel cell is continued even when the state of charge of the secondary battery is equal to or higher than the predetermined value, the driving power is not insufficient when the accelerator is depressed next time. Power can be stably supplied to the motor.

It is a block diagram which shows the structure of the control system of the vehicle carrying the control apparatus of the fuel cell vehicle which concerns on this invention. 1 is a schematic configuration diagram showing a braking system and a drive system of a fuel cell vehicle according to the present invention. 4 is a general flowchart of regenerative cooperative control in the control apparatus for a fuel cell vehicle according to the present invention. It is a schematic block diagram which shows the power plant of a fuel cell. 3 is a time chart illustrating regenerative cooperative control in the control device for a fuel cell vehicle according to the first embodiment. 3 is a flowchart of regenerative cooperative control in the control apparatus for a fuel cell vehicle according to the first embodiment. It is a flowchart of the regeneration cooperation control in the control apparatus of the fuel cell vehicle of Example 2. 6 is a flowchart of regenerative cooperative control in a control device for a fuel cell vehicle according to a third embodiment.

Explanation of symbols

10 ... running control computer,
11 ... Fuel cell,
12 ... motor,
15 ... an inverter,
16 ... Battery,
17 ... differential gear,
20 ... brake computer,
21 ... Brake hydraulic pressure source,
22 ... hydraulic pressure adjusting part,
23 ... Hydraulic brake,
30 ... Brake sensor,
31 ... Vehicle speed sensor,
32 ... accelerator sensor,
33. Longitudinal acceleration sensor,
101 ... Motor ECU,
102 ... Battery ECU,
103: Fuel cell computer.

Claims (3)

A fuel cell that generates power by receiving supply of a fuel gas containing hydrogen and an oxidant gas containing oxygen;
Rechargeable secondary battery,
A vehicle drive motor capable of driving the vehicle with electric power supplied from at least one of the fuel cell and the secondary battery and performing regenerative braking for converting rotational energy into electrical energy during vehicle braking;
In a fuel cell vehicle comprising a friction braking device that brakes the vehicle with frictional force,
Braking control means capable of using both regenerative braking by the vehicle drive motor and braking by the friction braking device during vehicle braking; and
Fuel cell control means for controlling the fuel cell to a state where electric power can be taken out before shifting from the braking state by the regenerative braking to the braking state by only the friction braking device;
A control apparatus for a fuel cell vehicle, comprising: Vehicle speed detection means;
Longitudinal acceleration detection means,
Based on the detected longitudinal acceleration and vehicle speed, the braking state transition time from the braking state by the regenerative braking to the transition to the braking state by the friction braking device is estimated and calculated,
Comparing the braking state transition time with the starting time required until starting the fuel cell, and starting the fuel cell starting control when it is determined that the braking state transition time is shorter than the starting time. 2. The control device for a fuel cell vehicle according to claim 1, wherein: A charge state detection means for detecting a charge state of the secondary battery;
The fuel cell control means includes
When the startup time is longer than the braking state transition time, power generation of the fuel cell is started even if the charging state exceeds a predetermined value, while the startup time is shorter than the braking state transition time. 3. The fuel cell vehicle control device according to claim 2, wherein start / stop of the fuel cell is controlled in accordance with a comparison between the state of charge and a predetermined value.

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