JP2009159789A - Vehicle and drive torque control device thereof - Google Patents

Abstract

An object of the present invention is to prevent a fuel cell system from generating excessive power beyond vehicle running power due to an accelerator off during traction control.
An HV-EUC 12 includes a TRC torque smoothing processing unit 112 that performs a smoothing process on a traction control command torque 111 for matching a slip amount of a driving wheel with a target slip amount, an accelerator opening degree, and a vehicle speed. An accelerator torque smoothing processing unit 123 that performs a smoothing process on the accelerator torque 121 to be obtained, a TRC command torque 111 after the smoothing process, and an accelerator torque 121 after the smoothing process are subjected to an upper limit process to obtain a torque final command value 133. A TRC torque processing unit.
[Selection] Figure 2

Description

  The present invention relates to a vehicle equipped with a fuel cell as a power source and a drive torque control device thereof.

  A fuel cell is an energy conversion system for causing an electrochemical reaction by supplying a fuel gas and an oxidizing gas to a membrane-electrode assembly and converting chemical energy into electric energy. In particular, a solid polymer electrolyte fuel cell using a solid polymer membrane as an electrolyte is expected to be used as an in-vehicle power source because it is low-cost and easy to downsize and has a high output density. For example, Japanese Patent Application Laid-Open No. 2001-204107 is known as a patent document that refers to traction control of a vehicle equipped with a fuel cell as an in-vehicle power source.

  FIG. 5 shows a functional block diagram of a control unit 15 mounted on a conventional fuel cell vehicle. The control unit 15 includes an ECB-ECU (electronically controlled brake system control unit) 13 that performs traction control and an HV-ECU (hybrid control unit) that controls a hybrid system (a power supply system including a fuel cell and a power storage device). 14. The ECB-ECU 13 performs traction control when the difference between the drive wheel speed and the driven wheel speed, or the difference between the left and right drive wheel speeds exceeds a predetermined threshold, and the slip amount of the drive wheel matches the target slip amount. Thus, the TRC (traction control) command torque 131 is calculated and the TRC command flag 132 is turned on to notify the HV-ECU 14 that the traction control is being performed.

  The TRC control torque calculation unit 142 performs processing for converting the TRC command torque 131 (wheel shaft torque) into motor shaft torque, and the like. The HV-ECU 14 calculates the accelerator torque 141 based on the accelerator opening and the vehicle speed. Here, an upper limit process by the TRC torque processing unit 143 and a torque smoothing process by the torque smoothing processing unit 144 will be described with reference to FIG. FIG. 6 assumes a case where the fuel cell vehicle in gripping starts traction control at time T5. Here, for convenience of explanation, the TRC command torque 131 is an upper limit torque value (power running torque at time T5). Consider the case where the accelerator torque 141 maintains a certain torque value Trq8 while the torque value Trq9 decreases from the maximum value Trq9. The TRC torque processing unit 143 performs upper limit processing on the TRC command torque 131 and the accelerator torque 141 to obtain a torque command value 272. The upper limit process is a process in which the smaller value of the plurality of torque command values is used as the torque value. Before time T5 when accelerator torque 141 <TRC command torque 131 is satisfied, the value of torque command value 272 is the same as the value of accelerator torque 141. After time T0 when TRC command torque 131 <accelerator torque 141 is satisfied, torque command value 272 is the same. The value 272 is the same as the TRC command torque 131 value.

The torque smoothing processing unit 144 performs torque smoothing on the torque command value 272 to obtain a torque final command value 272A. When the torque fluctuation is abrupt, drivability deteriorates. Therefore, the torque fluctuation can be smoothed by applying torque smoothing. However, during traction control, an annealing constant that is smaller than the annealing constant during grip traveling is applied from the viewpoint of increasing the response speed of the traction motor and quickly matching the slip amount of the drive wheels with the target slip amount. ing. Based on the TRC command flag 132 transmitted from the ECB-ECU 13, the torque smoothing processing unit 144 determines whether to apply the smoothing constant during grip traveling or the smoothing constant during traction control. .
JP 2001-204107 A

  However, when the accelerator is suddenly turned off during the traction control and the traction control is stopped, the switching of the annealing constant by the torque smoothing processing unit 144 is delayed due to a communication delay between the ECB-ECU 13 and the HV-ECU 14. Then, although the vehicle is gripping, the torque smoothing processing unit 144 applies the smoothing constant at the time of traction control for a while to narrow down the torque final command value 272A. Fuel cell power generation cannot follow the decrease. In this way, the power generated excessively exceeding the vehicle running power is overcharged to the power storage device, which may cause damage to the power storage device.

  Therefore, an object of the present invention is to propose a vehicle and a driving torque control device for the vehicle that suppress the surplus power generation by the fuel cell system beyond the vehicle running power due to the accelerator off during traction control.

  In order to solve the above-described problem, a vehicle drive torque control device according to the present invention provides a traction control torque smoothing process that performs a smoothing process on a traction control command torque for making a slip amount of a drive wheel coincide with a target slip amount. An accelerator torque smoothing processing unit that performs a smoothing process on the accelerator torque determined by the accelerator opening and the vehicle speed, and an upper limit process for the traction control command torque after the smoothing process and the accelerator torque after the smoothing process. A traction control torque processing unit for obtaining a final torque command value. By subjecting the traction control command torque and the accelerator torque to smoothing independently, it is possible to suppress the fuel cell system from generating excessive power beyond the vehicle running power due to the accelerator being turned off during traction control.

  The drive torque control device preferably further includes a correction unit that corrects the final torque command value so that the final torque command value falls from the start of traction control. Thereby, the traction control excellent in responsiveness can be implemented.

  When the shift position is changed to the neutral range or the parking range during traveling in the forward range or reverse range, the drive torque control device will change the value of the torque final command value when the shift position is changed after the shift position is changed. It is preferable to further include a correction unit that corrects the value of the final torque command value to be equal to the value of the traction control command torque at the time of change of the shift position until it falls below the value of the traction control command torque. As a result, it is possible to suppress the increase in torque when the shift range is changed from the forward range or the reverse range to the neutral range or the parking range.

  A vehicle according to the present invention includes a vehicle drive torque control device according to the present invention, a traction motor that drives drive wheels, and a fuel cell system that supplies electric power to the traction motor. Even if the accelerator is turned off for the traction control, it is possible to suppress the fuel cell system from generating excessive power beyond the vehicle running power.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a fuel cell system exceeds vehicle driving | running | working electric power, and generates electric power excessively by the accelerator off in traction control.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a system configuration of a fuel cell system 100 that functions as an in-vehicle power supply system for a fuel cell vehicle.

  The fuel cell stack 40 is a solid polymer electrolyte cell stack formed by stacking a large number of cells in series. The fuel cell stack 40 is a membrane-electrode junction in which an anode electrode 42 and a cathode electrode 43 are formed by screen printing or the like on both surfaces of a polymer electrolyte membrane 41 made of a proton conductive ion exchange membrane or the like made of a fluorine resin or the like. A body (MEA) 44 is provided. Both surfaces of the membrane-electrode assembly 44 are sandwiched by a ribbed separator (not shown), and a grooved anode gas channel and cathode gas channel are formed between the separator and the anode electrode 42 and the cathode electrode 43, respectively. In the fuel cell stack 40, the oxidation reaction of the formula (1) occurs at the anode electrode, and the reduction reaction of the equation (2) occurs at the cathode electrode. In the fuel cell stack 40 as a whole, an electromotive reaction of the formula (3) occurs.

_{^{H 2 → 2H + + 2e -}} ... (1)
(1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
H ₂ + (1/2) O ₂ → H ₂ O (3)

  A voltage sensor 91 for detecting the output voltage of the fuel cell stack 40 and a current sensor 92 for detecting the output current are attached to the fuel cell stack 40.

  The fuel gas supply source 70 is composed of, for example, a high-pressure hydrogen tank or a hydrogen storage alloy, and stores high-pressure (for example, 35 MPa to 70 MPa) hydrogen gas. The supply pressure of the hydrogen gas is regulated by the pressure regulating valve 71. The oxidizing gas supply source 80 is, for example, an air compressor that pressurizes air taken from the atmosphere and supplies pressurized air (oxidizing gas). The supply pressure of the pressurized air is regulated by the pressure regulating valve 81.

  The fuel cell system 100 is configured as a parallel hybrid system in which a DC / DC converter 30 and a traction inverter 60 are connected to the fuel cell stack 40 in parallel. The DC / DC converter 30 boosts the DC voltage supplied from the battery 20 and outputs it to the traction inverter 60, and the DC power generated by the fuel cell stack 40 or the regenerative power recovered by the traction motor 61 by regenerative braking. And the function of charging the battery 20 by lowering the voltage. The charge / discharge of the battery 20 is controlled by these functions of the DC / DC converter 30. Further, the operation point (output voltage, output current) of the fuel cell stack 40 is controlled by voltage conversion control by the DC / DC converter 30.

  The battery 20 functions as a surplus power storage source, a regenerative energy storage source during regenerative braking, and an energy buffer during load fluctuations associated with acceleration or deceleration of the fuel cell vehicle. The battery 20 is preferably a secondary battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium secondary battery. An SOC sensor 21 for detecting SOC (State of charge) is attached to the battery 20.

  The traction inverter 60 is, for example, a PWM inverter driven by a pulse width modulation method, and converts a DC voltage output from the fuel cell stack 40 or the battery 20 into a three-phase AC voltage in accordance with a control command from the control unit 10. Thus, the rotational torque of the traction motor 61 is controlled. The traction motor 61 is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.

  Auxiliary machines 50 are motors (for example, power sources such as pumps) disposed in each part of the fuel cell system 100, inverters for driving these motors, and various on-vehicle auxiliary machines. (For example, an air compressor, an injector, a cooling water circulation pump, a radiator, etc.) is a general term.

  The control unit 10 is an HV that controls an ECB-ECU (electronic control brake system control unit) 11 that performs traction control of the fuel cell vehicle and a hybrid system (a power supply system that includes the fuel cell stack 40 and the power storage device 20). A computer system including an ECU (hybrid control unit) 12. The control unit 10 receives output signals from various sensors (for example, the voltage sensor 91, the current sensor 92, the SOC sensor 21, etc.) and controls each part of the fuel cell system 100. For example, when the control unit 10 receives the start signal IG output from the ignition switch, the control unit 10 starts the operation of the fuel cell system 100, and the accelerator opening signal ACC output from the accelerator sensor or the vehicle speed output from the vehicle speed sensor. Based on the signal VC and the like, the vehicle running power and the auxiliary machine power consumption are calculated.

  Here, auxiliary electric power includes electric power consumed by in-vehicle auxiliary equipment (humidifier, air compressor, hydrogen pump, cooling water circulation pump, etc.), and equipment required for vehicle travel (transmission, wheel control device, steering) Power consumed by devices, suspension devices, etc.), power consumed by devices (air conditioners, lighting equipment, audio, etc.) disposed in the passenger space, and the like.

  Then, the control unit 10 determines the distribution of the output power of each of the fuel cell stack 40 and the battery 20, and the fuel gas supply source 70 and the oxidizing gas so that the power generation amount of the fuel cell stack 40 matches the target power. By controlling the supply of the reaction gas from the supply source 80 and controlling the DC / DC converter 30 to adjust the output voltage of the fuel cell stack 40, the operating point (output voltage, output current) of the fuel cell stack 40 is controlled. To control. Further, the control unit 10 outputs the U-phase, V-phase, and W-phase AC voltage command values to the traction inverter 60 as switching commands, for example, so as to obtain a target torque according to the accelerator opening, The output torque of the traction motor 61 and the rotation speed are controlled. The output torque of the traction motor 61 is transmitted to the drive wheels 63L and 63R via the reduction gear 62.

FIG. 2 shows functional blocks of the control unit 10.
The ECB-ECU 11 performs traction control when the difference between the drive wheel speed and the driven wheel speed or the difference between the left and right drive wheel speeds exceeds a predetermined threshold, and the slip amount of the drive wheel becomes the target slip amount. Thus, the TRC command torque 111 is calculated, and the TRC command flag 112 is turned on to notify the HV-ECU 12 that traction control is being performed.

  The TRC control torque calculation unit 122 converts the TRC command torque 111 (wheel shaft torque) into motor shaft torque, and calculates processing according to the shift position (for example, the shift position is in the N range (neutral position) or P range ( In the case of the parking position), the traction control is stopped, and when the shift position is in the R range (reverse drive position), processing such as reversing the sign of the TRC command torque 111 is performed.

  The HV-ECU 12 calculates the accelerator torque 121 based on the accelerator opening and the vehicle speed. Here, the torque smoothing process by the accelerator torque smoothing process part 123 and the TRC torque smoothing process part 124 and the upper limit process by the TRC torque process part 125 will be described with reference to FIG. FIG. 3 assumes a case where the fuel cell vehicle in gripping starts traction control at time T1, and here, for convenience of explanation, the TRC command torque 111 is changed from the upper limit torque values Trq3 to Trq1 at time T1. On the other hand, the case where the accelerator torque 121 maintains a certain torque value Trq2 is considered. The accelerator torque smoothing processing unit 123 performs torque smoothing on the accelerator torque 121 to obtain a torque command value 121A. Similarly, the TRC torque smoothing processing unit 124 performs torque smoothing on the TRC command torque 111 to obtain a torque command value 111A. The TRC torque processing unit 125 performs an upper limit process on the torque command values 121A and 111A to obtain a torque command value 132. Before time T2 when torque command value 121A <torque command value 111A, the value of torque command value 132 is the same as the value of torque command value 121A, and after time T2 when torque command value 111A <torque command value 121A. The value of the torque command value 132 is the same as the value of the torque command value 111A.

  Here, time T1 is a traction control start time, and time T2 is a time when the torque command value 132 starts to fall. In order to perform traction control with excellent responsiveness, the torque command value 132 needs to fall from time T1. Therefore, the HV-ECU 12 corrects the torque command value 132 so that the torque command value 132 falls from the traction control start time, and obtains a torque final command value 133. More specifically, the torque command value 132 is corrected so that the intersection point B between the torque command value 111A and the torque command value 121A moves to the intersection point C between the TRC command torque 111 and the torque command value 121A. 133 is obtained. This correction processing may be performed by the TRC torque processing unit 125 or may be performed by the TRC torque smoothing processing unit 124.

  In this manner, the TRC command torque 111 and the accelerator torque 121 are each independently smoothed, so that it is possible to suppress the fuel cell system 100 from generating excessive power beyond the vehicle running power due to accelerator off during traction control. .

  Next, a calculation process for obtaining the final torque limit 133 when the shift position is changed to the N range during traction control in the D range (forward position) will be described with reference to FIG. Here, it is assumed that the shift position of the fuel cell vehicle under traction control is changed from the D range to the N range at time T3, and the traction control is stopped simultaneously with the change of the shift position. The TRC command torque 111 maintains a small torque value Trq4 during traction control before the time T3, and jumps from the torque value Trq4 to the upper limit torque value Trq5 when the time T3 is reached. By applying torque smoothing to the TRC command torque 111, a torque command value 111A is obtained. On the other hand, accelerator torque 121 maintains a certain torque value Trq6 before time T3, and decreases from torque value Trq6 to 0 when time T3 is reached. By applying torque smoothing to the accelerator torque 121, a torque command value 121A is obtained.

  The torque command value 132 is obtained by subjecting the torque command values 111A and 121A thus obtained to an upper limit process. As can be understood from FIG. 4, the phenomenon of the torque command value 132 jumping up is observed at the moment of the shift change (time T3). If such a phenomenon occurs at the time of a shift change, the passenger feels uncomfortable, which is not preferable. Therefore, the HV-ECU 12 is a TRC command when the value of the torque command value 132 is changed from the time when the shift position is changed until the value of the torque command value 132 falls below the value Trq4 of the TRC command torque 111. Correction is made to be equal to the value Trq4 of the torque 111, and a final torque command value 133 is obtained. This correction processing may be performed by the TRC torque processing unit 125 or may be performed by the TRC torque smoothing processing unit 124.

  Further, for convenience of explanation, the correction processing when changing the shift position to the N range during the traction control in the D range has been illustrated, but the shift position during the traction control in the traveling range (for example, the D range or the R range) is exemplified. Even when the range is changed to a range other than the travel range (for example, the N range or the P range), a torque surging phenomenon occurs, and therefore it is preferable to perform the same correction process.

It is a block diagram of the fuel cell system concerning this embodiment. It is a functional block diagram of the control unit concerning this embodiment. It is a figure explaining the signal processing of the control unit concerning this embodiment. It is a figure explaining the signal processing of the control unit concerning this embodiment. It is a functional block diagram of the conventional control unit. It is a figure explaining the signal processing of the conventional control unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Control unit 11 ... ECB-ECU 12 ... HV-ECU 20 ... Battery 40 ... Fuel cell stack 61 ... Traction motor 100 ... Fuel cell system

Claims (4)

A traction control torque smoothing processing unit that performs a smoothing process on the traction control command torque for matching the slip amount of the drive wheel with the target slip amount;
An accelerator torque smoothing processing unit for smoothing the accelerator torque determined by the accelerator opening and the vehicle speed;
A traction control torque processing unit that performs an upper limit process on the traction control command torque after the annealing process and the accelerator torque after the annealing process to obtain a torque final command value;
A vehicle drive torque control device. The vehicle drive torque control device according to claim 1,
A driving torque control device for a vehicle, further comprising: a correction unit that corrects the final torque command value so that the final torque command value falls from a traction control start time. A drive torque control device for a vehicle according to claim 1 or 2,
If the shift position is changed to the neutral range or the parking range during traveling in the forward range or reverse range, the torque final command value after the shift position is changed is the traction control command torque when the shift position is changed. A drive torque control device for a vehicle, further comprising: a correction unit that corrects the value of the final torque command value so as to be equal to the value of the traction control command torque at the time of the shift position change until the value falls below this value. A vehicle drive torque control device according to any one of claims 1 to 3,
A traction motor that drives the drive wheels;
A fuel cell system for supplying power to the traction motor;
A vehicle further comprising:

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