JP2013085373A - Vehicle with energy-saving traveling function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle with an energy-saving traveling function, in which energy efficiency during traveling can be improved at low cost, the vehicle having an electric motor as a power source for travel driving.SOLUTION: The vehicle with the energy-saving traveling function includes a power supply device 10 for supplying power to an electric motor 3, and a power changing means for changing power to a wheel 4, and the power supply device 10 is configured so that an accelerator operation amount decides a command value of drive current to the electric motor 3. A control part is provided with energy-saving travel control which previously obtains a model formula for determining power loss during travel based on characteristics of the vehicle and the electric motor 3, derives a model formula having a variable of only a control value for changing power transmitted to the wheel 4, by detection values of vehicle speed and drive current, obtains a control value for reducing power loss from the model formula, and controls a power changing means based on the control value, and the control part performs the energy-saving travel control while the wheel 4 is driven by only power of the electric motor 3.

Description

  The present invention relates to an automobile with an energy saving traveling function including an electric motor as a power source.

  With the recent increase in interest in environmental problems, development of automobiles using an electric motor as a power source is rapidly progressing instead of an internal combustion engine that emits exhaust gas. Such automobiles generally drive an electric motor by supplying power from a battery, but the distance that can be traveled by charging a single battery is shorter than when an internal combustion engine such as a gasoline engine is used. How to improve the energy efficiency of time is important.

  For example, a power supply device that supplies power to the electric motor, a transmission device that transmits power from the electric motor to the wheels, and a current value detection means that detects the value of the drive current supplied from the power supply device to the electric motor; There is provided an automobile shown in Patent Document 1 provided with a power fluctuation means for changing power transmitted to a wheel in the electric motor or the transmission device, and provided with a control unit for controlling driving of the wheel via the power fluctuation means. It is publicly known.

  Specifically, a stator and a rotor that has the same axis and is rotatable with respect to the stator are provided in the starter, and a permanent magnet facing the coil winding is provided on the rotor. The electric motor moves the stator in the axial direction with respect to the rotor, thereby changing the effective magnetic flux and changing the power.

  Then, the control unit performs PWM control of the drive current, and when it is detected that the duty ratio of the drive current is maximized, the effective magnetic flux is reduced through the power fluctuation means to improve the traveling efficiency. ing.

  However, this is a rough two-step control of whether or not the duty ratio of the drive current during PWM control is maximum, and is insufficient from the viewpoint of improving energy efficiency. This also applies to the case where a speed change device that changes the rotational speed of the power transmitted from the electric motor to the wheels is used as the power fluctuation means.

  By the way, a transmission that includes an internal combustion engine as a power source, shifts the rotational speed of the power transmitted from the engine to the wheels, a microcomputer (control unit) that performs shift control of the transmission, and an engine rotational speed detection means. Vehicle speed detecting means for detecting the vehicle speed and throttle opening detecting means for detecting the throttle opening for determining the amount of fuel to be supplied to the engine, and the engine speed at which fuel efficiency is improved is derived from the throttle opening and the vehicle speed. A three-dimensional high fuel efficiency shift map is created in advance and stored in the storage unit of the microcomputer, and the microcomputer determines from the detected engine speed, the vehicle speed, and the throttle opening degree based on the high fuel efficiency shift map. The automobile shown in Patent Document 2 in which the shift control is performed and the fuel efficiency is improved is known.

  This high fuel efficiency shift map can be created even when an electric motor is used as a power source by making the drive current a variable instead of the slot opening, and thereby the power of the power fluctuation means (transmission device). It is possible to improve the running efficiency by finely controlling the fluctuation.

Japanese Patent Laying-Open No. 2008-220108 (FIG. 2) JP 2008-164028 A (FIG. 3-5)

  However, the high fuel efficiency shift map is created based on a large amount of experimental data using an actual machine, and changes depending on the combination of the power source and the power fluctuation means. It takes time and cost.

  An object of the present invention is to provide an automobile with an energy-saving running function that is an automobile equipped with an electric motor as a power source for running driving and can improve energy efficiency during running at low cost.

  In order to solve the above problems, first, a power supply device 10 that supplies power to the electric motor 3, a transmission device 9 that transmits power from the electric motor 3 to the wheels 4, and the electric motor 3 from the power supply device 10. A current value detecting means 23 for detecting the value of the drive current supplied to the vehicle and a vehicle speed detecting means 26 for detecting the vehicle speed, and the power fluctuation means for changing the power transmitted to the wheels 4 is the electric motor 3 or In an automobile provided with the transmission device 9 and provided with a control unit 22 for controlling the driving of the wheels 4 via the power fluctuation means, the command value of the drive current is determined by the accelerator operation amount detected by the accelerator operation detection means 12. Based on the characteristics of the power supply device 10 and the vehicle and the electric motor 3, a model equation for determining the power loss during traveling is obtained in advance, and the detected vehicle speed and drive current value are used. A model equation in which only the control value for changing the power transmitted to the wheel 4 is a variable is derived, a control value for reducing the power loss is obtained from the model equation, and the power loss is calculated based on the obtained control value. The control unit 22 is provided with energy-saving travel control for controlling the power fluctuation means so that the power fluctuation means becomes smaller. The control unit 22 performs energy-saving travel control only while the wheels 4 are driven only by the power from the electric motor 3. It is characterized by executing.

  Secondly, the power transmission device 9 is provided with a speed change mechanism 17 for shifting the power transmitted from the electric motor 3 to the wheel 4 to constitute a power fluctuation means, and the control value transmits the power from the electric motor 3 to the wheel 4. In this case, the speed ratio is a value.

  Third, the power fluctuation means is constituted by an electromagnet 39 that fluctuates the magnetic field in the electric motor 3 by changing the excitation current, and the control value becomes the value of the excitation current.

  Fourth, the power fluctuation means is constituted by a permanent magnet 42 that fluctuates the magnetic field in the electric motor 3 due to the displacement in the electric motor 3, and the control value becomes the displacement amount of the permanent magnet 42.

  Fifth, the temperature detection means 32 for detecting the temperature of the electric motor 3 is provided, and the control unit 22 determines the parameters included in the model equation according to the temperature detected by the temperature detection means 32 during execution of the energy saving travel mode. It is characterized by varying at least a part.

  Sixth, the current value detecting means 23 is characterized by detecting the value of the drive current via the filter 20.

  A model equation for obtaining power loss during traveling is obtained in advance, and a model equation in which only the control value for changing the power transmitted to the wheel is a variable is derived according to the detected vehicle speed and drive current value. From this, a control value for reducing power loss is obtained, and based on the obtained control value, the power fluctuation means is controlled so as to reduce the power loss. Compared with the case of using, it becomes possible to improve the energy efficiency at the time of driving | running | working at low cost.

  In addition to this, the electric motor is directly controlled according to the accelerator operation amount by configuring the power supply device so that the command value of the drive current is determined by the accelerator operation amount detected by the accelerator operation detecting means. Therefore, the vehicle speed is increased / decreased with good response according to the accelerator operation, and the power fluctuation means is controlled according to the drive current reflecting the accelerator operation, so that the response of the accelerator operation and the energy efficiency at the time of traveling are reduced. Improvements can be achieved at a high level.

  In addition, temperature detection means for detecting the temperature of the electric motor is provided, and the control unit varies at least a part of the parameters included in the model equation according to the temperature detected by the temperature detection means during execution of the energy saving travel mode. Thus, the temperature information is taken into consideration, and the energy efficiency during traveling is further improved.

  Furthermore, since the current value detection means is provided via a filter, the drive current value and phase information can be detected more accurately.

It is a conceptual diagram which shows the structure of the motor vehicle to which this invention is applied. It is a block diagram of the control part mounted in this motor vehicle. It is a processing flowchart of the traveling control which a control part performs.

  The inventors of the present application obtain a model equation (power loss equation) for calculating a loss of power (power) during traveling in order to improve energy efficiency during traveling. Here, it has been found that the difficulty of obtaining the power loss equation is easier when the electric motor is used as the power source than when the engine which is an internal combustion engine is used as the power source, and the present invention uses this. It is a thing.

Embodiments of the present invention will be described below based on examples shown in the drawings.
FIG. 1 is a conceptual diagram showing the configuration of an automobile to which the present invention is applied. The automobile 1 is a hybrid type four-wheel automobile provided with an engine 2 that is an internal combustion engine and an electric motor 3 as a power source, and an FF drive system is adopted as a drive system. Note that the present invention can be applied to any vehicle having a mode in which the vehicle is driven and driven only by the electric motor 3, and may be a two-wheeled vehicle. Therefore, an electric vehicle having only the electric motor 3 as a power source may be used, and a driving method may be used. Without being limited to the FF drive method, an FR drive method or an MR drive method may be used.

  In addition, the illustrated vehicle includes front left and right wheels (front wheels) 4, 4, rear left and right wheels (rear wheels) 6, 6, and left and right wheels 4, 4, 6, 6 when turning and the like. A differential gear device (diff) 7 and 8 that absorbs the rotational speed difference, a transmission device 9 that transmits the power of the engine 2 and the electric motor 3 to the wheels 4 and 4, an accelerator pedal (accelerator operating tool) 11, An accelerator operation meter 12 that is an accelerator operation detecting means for detecting an accelerator operation via the accelerator pedal 11 and its operation amount, a battery 13, and electric power corresponding to the accelerator operation amount detected by the accelerator potentiometer 12 are electrically driven from the battery 13. An inverter 14 that is a power supply circuit to be supplied to the motor 3 and an inverter that is driven to generate power by the power of the engine 2 and that supplies the generated power to the battery 13. And a Taneta 16. Incidentally, the battery 13 and the inverter 14 constitute the power supply device 10.

  The transmission device 9 includes a CVT (transmission mechanism, power fluctuation means) 17 that continuously changes the rotational speed of the power transmitted to the wheels 4 and 4, and a hydraulic engine that intermittently transmits power transmission from the engine 2 to the CVT 17. The side clutch 18, a hydraulic electric motor side clutch 19 that interrupts the power transmission from the electric motor 3 to the CVT 17, and a hydraulic power generation side clutch 21 that interrupts the power transmission from the engine 2 to the alternator 16. The CVT 17 includes a pulley (not shown) that transmits power from the power sources 2 and 3, a pulley (not shown) that transmits power to the wheels 4 and 4, and the pair of pulleys. The pair of pulleys and the V belt are continuously stepped by a speed change actuator (electric motor in the illustrated example) 15. Speed is driven. Note that a transmission or the like having a plurality of shift stages may be employed as the transmission mechanism 17.

  The automobile 1 also uses the electric motor 3 as a generator during deceleration or traveling downhill, and a regenerative charging function that returns the generated power to the battery 13 via the inverter 14 or the like. It has.

  The vehicle 1 having the above configuration is configured such that the motor side clutch 19 is connected and the engine side clutch 18 is disconnected and the motor side clutch 19 is disconnected and the motor side clutch 19 is disconnected and operated. The engine-side clutch 18 is connected and operated, and has two traveling modes: an engine traveling mode in which the engine-side clutch 18 is traveled only by the power of the engine 2.

  In addition, the automobile 1 is connected to the power generation side clutch 21 when the engine 2 is driven, the alternator 16 is driven to generate power, the charging mode in which the generated power is stored in the battery, and the power generation side clutch 21 is disconnected. And a non-charge mode in which the alternator 16 is stopped.

  Further, according to the present automobile 1, when the driver performs an accelerator operation, the accelerator operation and the operation amount thereof are detected by the accelerator potentiometer 12, and the electric motor 3 is supplied from the inverter 14 according to the detected accelerator operation amount. The command value of the current (drive current) of the electric power supplied to the battery is determined, and the inverter 14 is operated directly so that the actually detected drive current approaches this command value. Since the value of the supplied drive current changes directly, the driver can perform an increase / decrease operation of the traveling speed without a sense of incongruity. Incidentally, the difference between the command value and the drive current detected immediately after the command is that the value of the drive current depends on the inclination angle of the road, the wind speed (air friction), the wheels 4, 6 This is because it also fluctuates due to the friction and the like. In other words, the information on the running state is reflected in the value of the drive current. In the present invention, attention is paid to information contained in the value of the drive current, and this is utilized.

  Then, travel control is performed by the CVT 17 via the speed change actuator 15 (power fluctuation control is performed by the power fluctuation means), travel mode switching control via the motor side clutch 19 and the engine side clutch 18, and the power generation side. Switching control between the charging mode and the non-charging mode via the clutch 21 is performed by a control unit 22 (see FIG. 2) including a microcomputer or the like.

FIG. 2 is a block diagram of a control unit mounted on the automobile.
On the input side of the control unit 22, a current sensor (current value detection means) 23 that detects the value of the drive current from the inverter 14 through the filter 20 and a transmission upstream of the differentials 7 and 8 are installed and traveled. A vehicle speed sensor (detection means) 26 for detecting the speed (vehicle speed), a motor side clutch sensor 27 for detecting the on / off state of the motor side clutch 19, an engine side clutch sensor 28 for detecting the on / off state of the engine side clutch 18, and the power generation side A power generation side clutch sensor 29 that detects the on / off state of the clutch 21, a speed change potentiometer 31 that detects the current gear ratio of the CVT 17, a temperature sensor (temperature detecting means) 32 that detects the temperature of the electric motor 3, and the battery 13. The battery remaining amount detecting means 33 for detecting the remaining amount is connected.

  Incidentally, the inverter 14 generates a DC voltage for PWM control when the electric motor 3 is a DC motor, and generates a three-phase AC voltage when the electric motor 3 is the AC motor 3. Further, the filter 20 extracts a predetermined physical quantity (for example, an average value of the PWM-controlled drive current, the d-axis component and the q-axis component of the three-phase AC drive current) from the drive current output from the inverter 14. The physical quantity is detected by the current sensor 23. This improves detection accuracy and control performance.

  On the output side of the control unit 22, there are a speed change actuator 15, a motor side clutch intermittent means 34 including a hydraulic valve for intermittently operating the motor side clutch 19 by supplying and discharging hydraulic oil, and an engine by supplying and discharging hydraulic oil. Engine side clutch on / off means 36 including a hydraulic valve for intermittently operating the side clutch 18; power generation side clutch on / off means 37 including a hydraulic valve for intermittently operating the power generation side clutch 21 by supplying and discharging hydraulic oil; and the engine 2 Is connected to engine start / stop means 38 for starting and stopping the engine.

  The control unit 22 switches the running mode depending on the running state, and switches between the charging mode and the non-charging mode depending on the remaining amount of the battery 13. For example, when the remaining amount of the battery 13 is low, switching to the engine traveling mode may be performed, and when the remaining amount of the battery 13 is large, switching to the motor traveling mode may be performed. When the traveling mode and the vehicle speed are high, switching control such as switching to the engine traveling mode is performed. In addition, switching to the charging mode may be performed when the remaining amount of the battery 13 is low, and switching to the non-charging mode may be performed when the remaining amount of the battery 13 is large.

  In addition, the control unit 22 performs the traveling control in order to improve energy efficiency during traveling in the motor traveling mode (specifically, to reduce the power consumption of the battery 13 during traveling).

FIG. 3 is a process flow diagram of travel control performed by the control unit.
The control unit 22 executes this control every predetermined time (specifically, at intervals of 0.001 to 0.5 seconds). When the process is started, the process proceeds to step S1. In step S1, the engine-side clutch sensor 28 detects whether the engine-side clutch 18 is engaged or not. If the engine-side clutch 18 is in the connected state, it is not in the state of being switched to the motor travel mode. If the engine side clutch 18 is in the disengaged state, the process proceeds to step S2.

  In step S2, the motor-side clutch sensor 27 detects whether the motor-side clutch 19 is engaged. If the motor-side clutch 19 is in a disconnected state, the motor-side clutch 19 is not switched to the motor travel mode. If the motor-side clutch 19 is in the connected state, the motor traveling mode has been switched, and the process proceeds to step S3.

  Thus, when the process proceeds from step S1 to step S2 to step S3, the energy-saving travel control is executed in the processes after step S3 to. That is, the energy saving travel control provided in the control unit 22 is executed only when the travel mode is the motor travel mode.

  In step S3, the current sensor 23 detects the value of the drive current, and the process proceeds to step S4. In step S4, the vehicle speed is detected by the vehicle speed sensor 26, and the process proceeds to step S5. In step S5, the temperature of the electric motor 3 is detected by the temperature sensor 32, and the process proceeds to step S6. In step S6, the detected drive current and vehicle speed values are substituted into the power loss equation obtained in advance so that the characteristics of the vehicle of the automobile 1 and the characteristics of the electric motor 3 are included as various parameters. move on.

  By the way, the power loss equation uses the speed ratio (control value) to the wheels 4 and 4 determined based on the CVT to be controlled as variables, and the detected drive current and vehicle speed values are substituted to control the power loss equation. The power loss equation with only the value as the variable is obtained. In addition, among the above-mentioned parameters, those which are at least related to the electric motor 3 and depend on the temperature are changed depending on the detected temperature. Details of this power loss equation will be described later.

  In step S7, an equation that minimizes (reduces) the loss power during traveling is derived based on the power loss equation, a control value is obtained by solving this equation, and the process proceeds to step S8. In step S8, the shift actuator 15 shifts the CVT 17 so that the calculated control value is equal to or closest to the actual control value (specifically, the control value detected by the shift potentiometer 31). Control is performed and the process is terminated.

  According to this configuration, the power loss is minimized or reduced according to the accelerator operation amount, the vehicle speed, the road inclination reflected in the value of the driving current, the friction of the wheels 3 and 4, the wind speed, etc. Since the control value to be reduced is calculated as appropriate and the CVT 17 is appropriately subjected to power fluctuation control, energy efficiency during traveling can be improved.

  In the example described above, the rotational speed of the power transmitted from the electric motor 3 to the wheels 4 and 4 is varied by the CVT 17, and the speed ratio in this case is used as the control value. You may comprise the power fluctuation means to fluctuate.

  In the above-described example, a stator and a rotor that has the same axis and is rotatable with respect to the stator are provided, and a coil winding to which a drive current is supplied is provided on the starter, and a permanent magnet that faces the coil winding is a rotor. However, a variable magnetic field motor using an electromagnet 39 instead of a permanent magnet may be used as shown by a virtual line in FIG.

  2 and 3, by changing the value of the excitation current supplied to the electromagnet 39, the effective magnetic flux, which is the magnetic flux that acts effectively at the time of power generation, is changed, and thus generated. The excitation power generating / variation means 41 for changing the excitation current supplied to the electromagnet 39 is connected to the output side of the control unit.

  The electromagnet 39 constitutes the power fluctuation means, and the control value in this case is an exciting current value. According to the configuration, the speed change mechanism 17 can be omitted, or the electromagnet 39 and the speed change mechanism 17 can be omitted. May be used in combination. Incidentally, since this control value is an output value from the control unit 22, it is not necessary to separately provide detection means such as a sensor on the input side of the control unit 22 in order to detect this value.

  Also in the electric motor 3, a movable permanent magnet 42 may be used as the magnet, and the permanent magnet 42 may be used as power fluctuation means. That is, the effective magnetic flux is changed by displacing the relative position of the permanent magnet 42 with respect to the coil winding.

  As this configuration, for example, as shown in Patent Document 1 described above, specifically, a moving actuator 43 that moves the stator in the axial direction with respect to the rotor as shown in phantom lines in FIGS. 2 and 3 is provided. While connected to the output side of the control unit 22, a displacement amount detecting means 44 for detecting the displacement amount of the permanent magnet 42 relative to the coil winding is connected to the input side of the control unit 22, and this displacement amount is used as a control value. .

  The transmission mechanism 17 can be omitted by the movable permanent magnet 42, or the movable permanent magnet 42 and the transmission mechanism 17 may be combined.

Next, the power loss equation will be described.
First, the power loss equation when only CVT 17 is used as the power fluctuation means will be described. The drive current and i _b, a torque constant of the drive motor 3 and K, when the speed ratio is the ratio of the vehicle speed with respect to the rotational speed of the electric motor 3 is n, the driving force F _p of the automobile 1 has the formula: The

Further, the vehicle speed is v, the mass of the vehicle body is M _b , the moment of inertia of the electric motor 3 is H _m , the acceleration during traveling is a, the air pressure resistance coefficient is F _a , the rolling resistance force is F _r , and the horizontal plane of the traveling surface If the inclination is Φ and the gravity at the time of inclination Φ is G (Φ), the equation of motion is expressed by the following equation. Incidentally, M _b + n ² H _m in the following formula means an equivalent mass of the vehicle body.

Here, the decrease in kinetic energy during deceleration and the decrease in potential energy during downhill travel are converted into electrical energy by the regenerative charging function described above and stored in the battery 13. Then, the power loss and p, the electrical resistance of the electric motor 3 and R, the hysteresis loss coefficient of the electric motor 3 and H _y, the overcurrent loss coefficient of the electric motor 3 and E _d, a forward voltage drop of the inverter 14 Is V _d , the power loss p is synonymous with the heat loss here. Therefore, the power loss equation for obtaining the heat loss is expressed as follows.

That is, the power loss is modeled by the resistance heat and hysteresis loss of the electric motor 3, the loss due to the forward voltage drop of the inverter 14, the loss due to the air resistance of the vehicle, and the loss due to the rolling resistance of the wheels 4. Here, it should be noted that the drive current _ib is linearly dependent on the speed ratio n. In this power loss equation, when the speed ratio n is a variable, the following equation is used to minimize the power loss p. It is necessary to solve.

  Specifically, the following quadratic equation is obtained.

  By solving the two-dimensional equation for the speed ratio n, the speed ratio n that minimizes the power loss p is obtained, and the CVT 17 is set so that the actual speed ratio is equal to or close to the determined speed ratio n. The shift control is performed via the control unit 22.

Next, the power loss formula when the electromagnet 39 is used as the power fluctuation means will be described. The exciting current and i _f, the torque constant of the drive motor 3 and k, when the gear ratio is n, the driving force F _p of the motor vehicle 1 is represented by the following equation. Incidentally, since the CVT 17 is not controlled here, the gear ratio n is a fixed value.

The equation of motion is the same as in the above-described example. When the resistance of the electromagnet 39 is _Rf , the power loss equation is expressed as follows.

That is, the power loss equation is modeled by adding the resistance heat loss of the electromagnet to the above example. Further, in this model equation, when the exciting current _if is a variable, the following equation needs to be solved to minimize the power loss p.

  Specifically, the following quadratic equation is obtained.

By solving a two-dimensional equation for the excitation current i _f, the exciting current i _f is derived for the power loss p minimized, the actual exciting current becomes equal or near said it derived the exciting current i _f As described above, the excitation current is controlled via the control unit 22.

  Next, the power loss formula when only the movable permanent magnet 42 is used as the power fluctuation means will be described. When the displacement amount of the permanent magnet 42 is θ, the equation of motion is calculated by the following equation.

  Furthermore, the power loss equation is as follows.

Then, the drive current i _b is noted that varies with displacement theta, formula for the theta to the power loss p minimized becomes as follows.

  Since this equation is also an algebraic equation using only the displacement θ as a variable, the control unit 22 can easily obtain a numerical solution or a value close to this numerical solution.

  Further, when the CVT 17 is combined with the power fluctuation means using the movable permanent magnet 42, the following equations of motion and power loss are obtained.

  Expressions for obtaining the displacement amount θ and the gear ratio n that minimize the power loss p are as follows.

  By solving this simultaneous equation and obtaining a numerical solution, the displacement θ and the gear ratio n that minimize the power loss p can be obtained.

Further, even when the CVT 17 is combined with the power fluctuation means using the electromagnet 39, it is possible to obtain the exciting current _if and the speed ratio n that minimize the power loss p by the same method. is there.

3 Electric motor (power source)
4 Front wheels
9 Transmission device 10 Power supply device 12 Accelerator potentiometer (accelerator operation detection means)
17 CVT (Power electric means, transmission mechanism)
22 Control unit (microcomputer)
23 Current sensor (current value detection means)
26 Vehicle speed sensor (vehicle speed detection means)
32 Temperature sensor (temperature detection means)
39 Electromagnet (power fluctuation means)
42 Permanent magnet (power fluctuation means)

Claims (6)

  An electric power supply device (10) for supplying electric power to the electric motor (3), a transmission device (9) for transmitting power from the electric motor (3) to the wheels (4), and an electric motor from the electric power supply device (10) Power that includes current value detection means (23) that detects the value of the drive current supplied to (3) and vehicle speed detection means (26) that detects the vehicle speed, and that changes the power transmitted to the wheels (4). In an automobile provided with fluctuating means in the electric motor (3) or the transmission (9) and provided with a control unit (22) for controlling driving of the wheels (4) via the power fluctuating means, accelerator operation detecting means ( 12 is a model formula for configuring the power supply device (10) so that the command value of the drive current is determined by the accelerator operation amount detected in 12), and determining the power loss during traveling based on the characteristics of the vehicle and the electric motor (3). Asking for A model equation in which only the control value for changing the power transmitted to the wheel (4) is a variable is derived according to the value of the vehicle speed and the driving current, and the control value for reducing the power loss is obtained from the model equation, Based on the determined control value, an energy-saving travel control for controlling the power fluctuation means so as to reduce the power loss is provided in the control unit (22), and the control unit (22) is connected to the electric motor (3). An automobile with an energy saving traveling function that executes energy saving traveling control only while the wheel (4) is driven only by the power of the vehicle.   The transmission device (9) is provided with a speed change mechanism (17) for shifting the power transmitted from the electric motor (3) to the wheel (4) to constitute power fluctuation means, and the control value is changed from the electric motor (3) to the wheel. The vehicle with an energy saving traveling function according to claim 1, which has a speed ratio value when power is transmitted to (4).   The power fluctuation means is constituted by an electromagnet (39) that fluctuates the magnetic field in the electric motor (3) by changing the excitation current, and the control value becomes the value of the excitation current. Automobile with energy saving running function.   The said power fluctuation means is comprised by the permanent magnet (42) which fluctuates the magnetic field in an electric motor (3) by the displacement in an electric motor (3), and a control value becomes the displacement amount of a permanent magnet (42). The automobile with an energy-saving running function according to either 1 or 2.   A temperature detection means (32) for detecting the temperature of the electric motor (3) is provided, and the control unit (22) determines the above model formula according to the temperature detected by the temperature detection means (32) during execution of the energy saving travel mode. The vehicle with an energy saving traveling function according to any one of claims 1 to 4, wherein at least a part of the included parameters is varied.   The vehicle with energy-saving travel function according to any one of claims 1 to 5, wherein the current value detection means (23) detects the value of the drive current through a filter (20).

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