JP2007244030A - Vehicle control device - Google Patents

Abstract

An object of the present invention is to quickly reduce the SOC of a secondary battery that supplies power to a rotating electrical machine without causing the driver to feel uncomfortable.
A control device 60 is a control device for a vehicle 1 capable of independently driving front wheels 48f and rear wheels 48r by corresponding rotating electrical machines MG2, MG3. When the SOC of the secondary battery 56 reaches a predetermined threshold value, the control device 60 gives one of the front wheels 48f and the rear wheels 48f a forward torque that is a torque in the direction in which the vehicle 1 moves forward, and the other. Controls the rotating electrical machines MG2 and MG3 so as to apply a reverse torque that is a torque in a direction in which the vehicle 1 is moved backward. By forcibly increasing the power consumption in the rotating electrical machines MG2 and MG3, the SOC of the secondary battery can be quickly reduced without causing the driver to feel uncomfortable.
[Selection] Figure 1

Description

  The present invention relates to control of a vehicle in which front wheels and rear wheels can be independently driven by corresponding rotating electric machines.

  2. Description of the Related Art In recent years, vehicles are known in which front wheels and rear wheels can be independently driven by corresponding rotating electric machines. For example, front wheels are driven by an internal combustion engine and rotating electric machines, and rear wheels are driven by front electric wheels. There are a hybrid vehicle that is driven by a rotating electric machine provided separately from the electric vehicle, and an electric vehicle that drives front and rear wheels by corresponding rotating electric machines. Such a vehicle is provided with a secondary battery for storing electric power supplied to the rotating electrical machine. When the vehicle is propelled, the vehicle can be propelled by supplying electric power from the secondary battery, operating the rotating electric machine as an electric motor, and driving the wheels. On the other hand, when the vehicle is decelerated, the rotating electrical machine is operated as a generator, and the torque transmitted from the wheel to the rotating electrical machine is converted into electric power, thereby generating a braking force on the wheel and decelerating the vehicle. So-called regenerative braking can be performed in which the converted power is collected by the secondary battery.

  When this regenerative braking is performed for a long time, the secondary battery may have an excessively large remaining battery capacity (hereinafter referred to as SOC) due to the collected power. If the state where the SOC is large is continued for a long time, various problems such as a reduction in the life of the secondary battery occur.

  In order to prevent this, the following Patent Document 1 discloses a function for forcibly consuming the electric power obtained by the rotating electrical machine (motor generator) when an overcharged state of a secondary battery (high voltage battery) is detected. A hybrid vehicle equipped with is proposed. In this vehicle, when the high-voltage battery is in an overcharged state, the electric power obtained by the rotating electrical machine is supplied to the hot wire heater for preventing fogging in the window of the vehicle and consumed here, so that the SOC of the battery is reduced. , Preventing further growth.

JP 2001-157306 A

  However, in the technique described in Patent Document 1, when the secondary battery (high voltage battery) is overcharged, the hot wire heater is automatically operated, so the driver operates the hot wire heater. Although it is not, the operation of the hot wire heater is perceived by the generated heat. If such an electrical component that can be perceived by the driver is actuated at an unintended timing, there is a problem that the driver feels a strong sense of incongruity.

  In the technique described in Patent Document 1, the electric power stored in the high-voltage battery is positively discharged simply by supplying the electric power obtained by the rotating electric machine to the hot wire heater instead of the high-voltage battery. I can't let you. In addition, the high voltage battery that supplies power to the rotating electrical machine has a higher capacity than the battery that supplies power to the electrical components in the passenger compartment. Therefore, a hot wire heater is connected to the battery to consume power. However, the SOC of the high voltage battery cannot be reduced quickly.

  Therefore, the present invention provides a vehicle control apparatus that can quickly reduce the SOC of a secondary battery that supplies power to a rotating electrical machine without causing the driver to feel uncomfortable.

  When the remaining capacity of the secondary battery that supplies power to the rotating electrical machine reaches a predetermined threshold value, the vehicle control device according to the present invention has one of the front wheels and the rear wheels in a direction in which the vehicle moves forward. The rotating electrical machine is controlled so that a forward torque, which is a torque, is applied, and a reverse torque, which is a torque in the direction of moving the vehicle backward, is applied to the other. By forcibly increasing the power consumption in the rotating electric machine, the SOC of the secondary battery can be quickly reduced without causing the driver to feel uncomfortable.

  Preferably, when the vehicle is moving forward by applying a forward torque to one of the front wheels and the rear wheels, the other wheel is controlled to give a reverse torque smaller than the forward torque when the remaining capacity reaches a predetermined threshold.

  According to the vehicle control apparatus of the present invention, the SOC of the secondary battery that supplies power to the rotating electrical machine can be quickly reduced without causing the driver to feel uncomfortable.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. As an example, a hybrid vehicle in which the front wheels are driven by an internal combustion engine and a rotating electric machine and the rear wheels are driven by another rotating electric machine will be described.

  First, the configuration of the hybrid vehicle 1 to which the control device 60 of the present embodiment is applied will be described with reference to FIG. FIG. 1 schematically shows a schematic configuration of the hybrid vehicle 1. In order to propel this, the hybrid vehicle 1 is provided with a front wheel drive unit 3 that drives the front wheels 48f and a rear wheel drive unit 5 that drives the rear wheels 48r. The front wheel drive unit 3 has an internal combustion engine 10 as a prime mover and rotating electric machines MG1 and MG2 that are electric motors capable of generating power, while the rear wheel drive unit 5 has a rotary electric machine MG3 as a prime mover. ing. Thereby, the front wheel 48f and the rear wheel 48r can be driven independently. These prime movers are controlled to operate cooperatively by a hybrid electronic control device 60 (hereinafter simply referred to as “ECU”) that controls the entire vehicle.

  The internal combustion engine 10 includes a fuel injection device, an ignition device, and a throttle valve (not shown), and these devices are controlled by the ECU 60. The ECU 60 can adjust mechanical power generated by the internal combustion engine 10, that is, engine torque. The engine torque generated by the internal combustion engine 10 is output from the crankshaft 12.

  On the other hand, the rotating electrical machines MG1, MG2, and MG3 have a function as an electric motor that converts supplied electric power into mechanical power and a function as a generator that converts input mechanical power into electric power. This is a so-called motor generator. The switching of these functions and the mechanical power generated by the rotating electrical machines MG1, MG2, and MG3 or the electric power to be recovered are controlled by inverters 51, 52, and 53 provided corresponding to the rotating electrical machines MG1, MG2, and MG3, respectively. ing. The ECU 60 can adjust the mechanical power generated by the rotating electrical machines MG1, MG2, and MG3, that is, the motor torque, by controlling the inverters 51, 52, and 53, respectively. Motor torque generated by the rotating electrical machines MG1, MG2, and MG3 is output from rotating shafts 31a, 32a, and 33a coupled to the rotors 31, 32, and 33, respectively. On the other hand, the mechanical power input to the rotating electrical machines MG1, MG2, and MG3 from the rotating shafts 31a, 32a, and 33a is converted into electric power here and can be recovered in the secondary battery 56 described later. .

  The front wheel drive unit 3 includes the planetary gear mechanism 20 that divides the engine torque output from the internal combustion engine 10 in addition to the internal combustion engine 10 and the rotary electric machines MG1 and MG2, and the rotation transmitted from the planetary gear mechanism 20. A speed reduction device 40f that decelerates and increases torque and a differential device 45f that distributes and outputs the mechanical power transmitted from the speed reduction device 40f to the left and right drive shafts 46f are integrally configured. The rotating electrical machine MG1 is mainly used as a generator, while the rotating electrical machine MG2 is mainly used as an electric motor.

  The planetary carrier 28 of the planetary gear mechanism 20 is coupled to the crankshaft 12 of the internal combustion engine 10, the sun gear 22 is coupled to the rotor 31 of the rotating electrical machine MG1, and the ring gear 24 is coupled to the rotor 32 of the rotating electrical machine MG2. . The engine torque output from the crankshaft 12 by the internal combustion engine 10 is divided into an engine torque transmitted from the planetary carrier 28 of the planetary gear mechanism 20 to the sun gear 22 and an engine torque transmitted to the ring gear 24. The engine torque transmitted from the internal combustion engine 10 to the sun gear 22 is transmitted to the rotating electrical machine MG1, where it is used for power generation. On the other hand, the engine torque transmitted from the internal combustion engine 10 to the ring gear 24 is integrated with the motor torque output from the rotating electrical machine MG2, and is transmitted from the ring gear 24 to the reduction gear 40f. The mechanical power transmitted from the speed reduction device 40f to the differential device 45f is distributed to the left and right drive shafts 46f here to drive the front wheels 48f.

  By configuring the front wheel drive unit 3 in this way, the rotating electrical machine MG2 can generate motor torque by the electric power supplied from the secondary battery 56 and drive it to the front wheels 48f during vehicle propulsion. it can. That is, the rotating electrical machine MG2 gives the front wheel 48f torque in the direction in which the vehicle 1 moves forward (hereinafter referred to as forward torque), and torque in the direction in which the vehicle 1 moves backward (hereinafter referred to as reverse torque). It is possible. Moreover, the rotating electrical machine MG2 can convert the mechanical power transmitted from the front wheels 48f into electric power and collect it in a secondary battery 56 described later during vehicle deceleration.

  On the other hand, in addition to the above-described rotating electrical machine MG3, the rear wheel drive unit 5 decelerates the rotation transmitted from the rotating electrical machine MG3 and increases the torque, and the mechanical power transmitted from the speed reducing device 40r. A differential device 45r that distributes to the drive shaft 46r is integrally coupled. The mechanical power output from the rotating electrical machine MG3 is transmitted from the reduction gear 40r to the differential device 45r and distributed to the left and right drive shafts 46r to drive the rear wheels 48r.

  By configuring the rear wheel drive unit 5 in this manner, the rotating electrical machine MG3 generates motor torque by the electric power supplied from the secondary battery 56 during vehicle propulsion, and applies this to the rear wheel 48r for driving. be able to. That is, the rotating electrical machine MG3 can apply forward torque or reverse torque to the rear wheel 48r. Further, the rotating electrical machine MG3 can convert the mechanical power transmitted from the rear wheel 48r into electric power and collect it in the secondary battery 56 described later during vehicle deceleration.

  Further, the vehicle 1 is provided with a secondary battery 56 that stores electric power to be supplied to the rotating electric machine. The secondary battery 56 is electrically connected to inverters 51, 52, 53 provided corresponding to the rotary electric machines MG1, MG2, MG3, respectively, and the rotary electric machines are respectively connected via the inverters 51, 52, 53. Power can be exchanged with MG1, MG2, and MG3. The exchange of electric power is controlled by the ECU 60.

  Secondary battery 56 supplies electric power to rotating electrical machines MG1, MG2, and MG3 when ECU 60 operates rotating electrical machines MG1, MG2, and MG3 as electric motors. On the other hand, when ECU 60 operates rotating electrical machines MG1, MG2, and MG3 as a generator, secondary battery 56 can collect and store the electric power (electric energy) obtained by rotating electrical machines MG1, MG2, and MG3. .

  The vehicle 1 is provided with a battery monitoring unit 58 for monitoring the secondary battery 56. The battery monitoring unit 58 monitors the temperature and voltage of the secondary battery 56, the charging / discharging current of the secondary battery 56, etc., and calculates the remaining capacity (hereinafter referred to as SOC) of the secondary battery 56 from these information. ing. The battery monitoring unit 58 sends the calculated SOC of the secondary battery 56 to the ECU 60.

  Further, the vehicle 1 is provided with an accelerator position sensor 62 for detecting an operation amount of an accelerator pedal (hereinafter referred to as an accelerator operation amount). The sensor 62 uses a signal of the detected accelerator operation amount as an ECU 60. Is being sent to. The vehicle 1 is provided with a shift position sensor 64 that detects an operation position of the shift lever (hereinafter referred to as a shift position). The sensor 64 sends a signal of the detected shift position to the ECU 60. is doing.

  Further, all four wheels (48f, 48r) of the vehicle 1 are provided with “wheel speed sensors” (not shown) for detecting the rotational speeds of the respective wheels. The wheel speed signal is detected. The ECU 60 calculates a front wheel rotation speed that is an average value of the rotation speeds of the left and right front wheels 48f and a rear wheel rotation speed that is an average value of the rotation speeds of the left and right rear wheels 48r. The speed of the vehicle 1 (hereinafter referred to as the vehicle speed) is determined from either one of the rear wheel rotational speeds.

  Further, the ECU 60 calculates the slip ratio from the difference between the front wheel rotation speed and the rear wheel rotation speed. When the front wheel rotation speed is higher than the rear wheel rotation speed, the value obtained by dividing the front wheel rotation speed by the rear wheel rotation speed is the "front wheel slip ratio". When the rear wheel rotation speed is higher than the front wheel rotation speed, A value obtained by dividing the wheel rotation speed by the rotation speed of the front wheel 48f is the "rear wheel slip ratio". Hereinafter, the front wheel slip ratio and the rear wheel slip ratio will be described simply as “slip ratio”. The slip ratio may be calculated by another electronic control device (not shown), and the calculation result may be received by the ECU 60.

  The ECU 60 receives the SOC signal of the secondary battery 56 from the battery monitoring unit 58, the accelerator operation amount signal from the accelerator position sensor 62, and the shift position signal from the shift position sensor 64, respectively. The ECU 60 calculates a driving force requested by the driver from the vehicle 1 (hereinafter referred to as a required driving force) from the accelerator operation amount. Based on the calculated required driving force and the SOC of the secondary battery 56, the ECU 60 outputs the engine torque to be output by the internal combustion engine 10, the motor torque to be output by the rotating electrical machines MG1, MG2, and MG3, and the rotating electrical machine MG1, Electric power to be generated by MG2 and MG3 is determined, and based on this determination, internal combustion engine 10 and rotating electrical machines MG1, MG2 and MG3 are controlled. The internal combustion engine 10 and the rotating electrical machines MG1, MG2, and MG3 are controlled to operate cooperatively according to the traveling state of the vehicle 1 including when the vehicle is stopped.

  The ECU 60 receives a shift position signal from the shift position sensor 64. When the shift position is in the D range, the ECU 60 advances the vehicle according to the required driving force calculated from the accelerator operation amount. On the other hand, when the shift position is in the R range, the vehicle is moved backward according to the required driving force. Further, when the shift position is the N range or the P range, the ECU 60 performs control so that the vehicle 1 is not propelled regardless of the accelerator operation amount.

  The hybrid vehicle 1 configured as described above can independently drive the front wheels 48f and the rear wheels 48r by the corresponding rotating electric machines MG2 and MG3. The vehicle 1 can be propelled forward or backward by driving at least one of the front wheels 48f and the rear wheels 48r.

  Further, at the time of deceleration of the vehicle, the hybrid vehicle 1 operates at least one of the rotary electric machine MG2 and the rotary electric machine MG3 as a generator, and uses mechanical power transmitted from the wheels 48 (front wheels 48f, rear wheels 48r) as electric power. By performing the conversion, it is possible to perform a so-called “regenerative braking” in which a braking force is generated in the wheel 48 to decelerate the vehicle 1 and the converted electric power is collected in the secondary battery 56.

  When such regenerative braking is performed on the vehicle for a long time, the SOC of the secondary battery 56 may become too large due to the electric power recovered by the rotating electrical machines MG2 and MG3. If the state of the SOC of the secondary battery 56 is continued, there arises a problem that the life of the secondary battery is reduced.

  Therefore, in the present embodiment, when the SOC of the secondary battery 56 reaches a predetermined threshold, the ECU 60 controls the magnitude and direction of the motor torque generated by the rotating electrical machines MG2 and MG3, thereby allowing the secondary battery 56 to The stored electric power is forcibly consumed by the rotary electric machine MG2 and the rotary electric machine MG3. Hereinafter, the control executed by the ECU 60 will be described with reference to FIGS. 2, 3A, 3B, and 4. FIG. FIG. 2 shows a flowchart of control executed by the ECU. 3A and 3B schematically show the torque applied to the wheels during forward movement of the vehicle, and FIG. 4 schematically shows the torque applied to the wheels while the vehicle is stopped.

  First, the ECU 60 receives signals from the various sensors and the electronic control device described above and detects necessary control variables (S100). The control variables include the SOC of the secondary battery 56, the required driving force, the vehicle speed, the slip ratio, the shift position, and the like. By detecting such a control variable, the ECU 60 grasps the current traveling state of the vehicle 1.

  In step S102, it is determined whether the SOC of the secondary battery 56 has reached a predetermined threshold value. This threshold is set to 75%, for example, and is stored in advance in the ROM 60a of the ECU 60. When it is determined that the SOC has reached the threshold value, that is, the SOC is large, the ECU 60 determines an increase in power consumption by the rotating electrical machine (MG2, MG3) (S104).

  In step S106, it is determined whether or not the vehicle 1 is moving forward. The ECU 60 determines whether or not the vehicle 1 is moving forward based on whether or not the calculated vehicle speed is a value indicating the forward movement of the vehicle 1 or whether or not the detected shift position is in the D range. can do.

  When it is determined that the vehicle is moving forward, the ECU 60 controls the rotating electrical machines (MG2, MG3) so as to give a reverse torque smaller than the forward torque (S108). For example, as shown in FIG. 3A, when the forward torque of 500 Nm is applied to the front wheel 48f (indicated by an arrow A in the figure) and the vehicle 1 is moving forward, the ECU 60 changes to FIG. As shown, the motor torque of the rotating electrical machine MG2 is increased so as to apply a forward torque of 1000 Nm (indicated by arrow B in the figure) to the front wheel 48f, and a reverse torque of 500 Nm (indicated by arrow C in the figure) is applied to the rear wheel 48r. ) To generate motor torque in the rotating electrical machine MG3. By controlling the rotating electrical machines (MG2, MG3) in this way, the power consumption in the rotating electrical machines MG2, MG3 is increased without changing the propulsive force of the vehicle 1, that is, the acceleration of the vehicle. Due to the power consumption by these rotating electrical machines (MG2, MG3), the SOC of the secondary battery 56 quickly decreases.

  On the other hand, if it is determined that the vehicle is not moving forward, it is determined whether or not the vehicle is moving backward (S110). The ECU 60 determines whether or not the vehicle 1 is moving backward based on whether or not the calculated vehicle speed is a value indicating the backward movement of the vehicle 1 or whether or not the detected shift position is in the R range. can do.

  When it is determined that the vehicle is moving backward, the ECU 60 controls the rotating electrical machines (MG2, MG3) so as to apply a forward torque smaller than the reverse torque (S112). The rotating electrical machines (MG2, MG3) are controlled so that one of the front wheel 48f and the rear wheel 48r is given reverse torque, and the other is given a forward torque smaller than the reverse torque.

  On the other hand, if it is determined that the vehicle is neither forward nor reverse, it is determined that the vehicle is stopped and the process proceeds to step S114. The ECU 60 determines whether the vehicle 1 is stopped based on whether the calculated vehicle speed is zero, or whether the detected shift position is in the N range or the P range. You can also.

  When it is determined that the vehicle is stopped, the ECU 60 controls the rotating electrical machines (MG2, MG3) so as to give equal forward torque and reverse torque (S114). For example, as shown in FIG. 4, a motor torque is generated in the rotating electrical machine MG2 so that a forward torque of 500 Nm (indicated by an arrow D in the figure) is applied to the front wheel 48f, and a reverse torque of 500 Nm in the rear wheel 48r (in the figure). , The motor torque is generated in the rotating electrical machine MG3. By controlling the rotating electrical machines (MG2, MG3) in this way, power is consumed by the rotating electrical machines MG2, MG3 while the vehicle 1 is kept stopped. Due to the power consumption by these rotating electrical machines (MG2, MG3), the SOC of the secondary battery 56 quickly decreases.

  In step S118, it is determined whether or not the SOC of the secondary battery 56 has reached a predetermined target value. This target value is set to 50%, for example, and is stored in advance in the ROM of the ECU 60. Until the SOC reaches the target value, the ECU 60 increases power consumption by the control that applies the forward torque to one of the front wheels 48f and the rear wheel 48r and the reverse torque to the other, that is, the rotating electrical machines (MG2, MG3). Control (S104 to S114) is continued.

  In steps S108, S112, and S114, the values of the forward torque and the reverse torque that are increased by the rotating electrical machines (MG2, MG3) are ranges in which no slip occurs in the front wheels 48f and the rear wheels 48r, that is, the slip ratio is almost zero. Is set within. By setting the values of the forward torque and the reverse torque within a range where no slip occurs in the front wheel 48f and the rear wheel 48r, the power consumption by the rotating electrical machines MG2 and MG3 is increased without impairing the running stability of the vehicle. be able to.

  As described above, in the present embodiment, when the SOC of the secondary battery 56 reaches a predetermined threshold, one of the front wheels and the rear wheels is given a forward torque and the other is given a reverse torque. Electric machines MG2 and MG3 are controlled. By forcibly increasing the power consumption in the rotating electrical machines MG2 and MG3, the SOC of the secondary battery can be quickly reduced without causing the driver to feel uncomfortable.

  In addition, although this embodiment shall be applied to the hybrid vehicle 1 provided with the internal combustion engine 10 and rotary electric machine MG2, MG3 as a motor | power_engine, this invention is not limited to this embodiment. The present invention can be applied to any vehicle that can independently drive the front wheels and the rear wheels by the corresponding rotating electric machines. For example, the present invention can also be applied to an electric vehicle that includes only the rotating electric machine as a prime mover.

It is a figure showing a schematic structure of a hybrid vehicle to which this embodiment is applied. It is a flowchart figure of the control which this embodiment performs. It is a figure which shows typically the torque provided to a wheel during vehicle advance by this embodiment, (a) is a case where SOC of a secondary battery has not reached the threshold value, (b) is a secondary battery. This shows a state where the SOC of the motor reaches the threshold value and reverse torque is applied. It is a figure which shows typically the torque given to a wheel during a vehicle stop by this embodiment.

Explanation of symbols

  1 vehicle, 3 front wheel drive unit, 5 rear wheel drive unit, 10 internal combustion engine, 20 planetary gear mechanism, 40f, 40r speed reducer, 45f, 45r differential device, 48f front wheel, 48r rear wheel, 51, 52, 53 inverter, 56 Secondary battery, 58 Battery monitoring unit, 60 ECU (electronic control unit), MG1, MG2, MG3 Rotating electric machine.

Claims (2)

A vehicle control device capable of independently driving front wheels and rear wheels by corresponding rotating electric machines,
When the remaining capacity of the secondary battery that supplies power to the rotating electrical machine reaches a predetermined threshold value,
One of the front wheels and the rear wheels is given a forward torque, which is a torque in the direction of moving the vehicle forward, and the other is controlled by a rotating electric machine so as to give a reverse torque, which is a torque in the direction of moving the vehicle backward,
Vehicle control device. The vehicle control device according to claim 1,
When moving forward with a forward torque applied to one of the front and rear wheels,
When the remaining capacity reaches a predetermined threshold value, the other capacity is controlled to give a reverse torque smaller than the forward torque.
Vehicle control device.

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