JP2013074770A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle that can reduce power consumption during EV running.SOLUTION: A motor-generator 20 receives electric power from a power storage device 12 and generates required running power. When the running power exceeds steady-state power that indicates an upper limit of the running power outputtable steadily, an ECU 24 expands the upper limit of the running power temporarily from the steady-state power to expanded power outputtable only for a predetermined permission time period. When the running power exceeds the steady-state power, the ECU 24 controls the motor-generator 20 within a range of a maximum energy amount determined by a difference between the expansion power and the steady-state power and the permission time period. Here, the ECU 24 makes the expanded power smaller as increasing speed of the running power becomes larger.

Description

  The present invention relates to an electric vehicle, and more particularly, to an electric vehicle that travels by an electric motor.

  2. Description of the Related Art In recent years, electric vehicles that run by an electric motor such as an electric vehicle (Electric Vehicle) and a hybrid vehicle (Hybrid Vehicle) have attracted attention as environmentally friendly vehicles. An electric vehicle is equipped with a DC power source and an electric motor as a driving power source. The hybrid vehicle includes a vehicle equipped with an electric motor as a driving power source in addition to a conventional internal combustion engine, and a vehicle equipped with a fuel cell as an energy source in addition to a DC power source.

  Japanese Patent Application Laid-Open No. 2008-230409 (Patent Document 1) discloses that a hybrid vehicle, which is a kind of electric vehicle, has a large acceleration performance when the engine is stopped and the vehicle is driven only by the electric motor (hereinafter referred to as “EV traveling”). Disclosed is a technique for suppressing damage. In this hybrid vehicle, when the drive torque reaches the maximum EV travelable torque according to the increase in the accelerator opening during EV travel, the drive torque is maintained at the maximum EV travelable torque until the accelerator opening further increases by a predetermined amount. Is done. Then, when the accelerator opening further increases beyond the predetermined amount, the vehicle is switched to HV traveling that operates by operating the engine.

  According to the present invention, it is easy to maintain EV traveling without suppressing the accelerator opening to a low level, and as a result, it is possible to suppress the acceleration performance from being impaired during EV traveling (see Patent Document 1).

JP 2008-230409 A JP 2008-296619 A JP 2008-174159 A JP 2008-126901 A JP-A-5-184015

  The hybrid vehicle described in Patent Document 1 is useful in that EV travel can be maintained without reducing the accelerator opening, but on the other hand, EV travel until the drive torque reaches the maximum EV travelable torque is achieved. If the accelerator pedal is depressed suddenly, the power consumption will also increase rapidly. In order to further promote so-called eco-driving, it is necessary to reduce power consumption even during EV traveling.

  Therefore, an object of the present invention is to provide an electric vehicle capable of reducing power consumption during EV traveling.

  According to the present invention, the electric vehicle includes a DC power source, an electric motor, and a control device. The electric motor receives electric power from the DC power source and generates the requested traveling power. The control device controls the electric motor so that the traveling power does not exceed the upper limit. Here, the control device decreases the upper limit of the traveling power as the increasing speed of the traveling power increases.

  Preferably, when the traveling power exceeds the steady power indicating the upper limit of the traveling power that can be output steadily, the control device temporarily increases the upper limit of the traveling power from the steady power to an expanded power that can be output for a predetermined permission time. Expanding. Here, the upper limit of the traveling power is the above-described enlarged power, and when the traveling power exceeds the steady power, the control device decreases the expanding power as the traveling power increases.

  Preferably, when the traveling power exceeds the steady power, the control device further controls the electric motor within the range of the maximum energy amount determined by the difference between the enlarged power and the steady power and the permission time.

  More preferably, when the traveling power exceeds the steady power, the control device, when the amount of energy obtained by integrating the value obtained by subtracting the steady power from the power supplied from the DC power source to the motor reaches the maximum energy amount. The travel power is limited to the steady power.

  Preferably, the electric vehicle further includes a detection unit. The detection unit detects an accelerator opening related to an operation amount of the accelerator pedal. The travel power is calculated based on the accelerator opening detected by the detection unit. And a control apparatus makes the upper limit of driving | running | working power small, so that the increase speed of an accelerator opening degree is large.

  Preferably, the control device learns the traveling situation and changes the upper limit of the traveling power based on the learning result.

  In the present invention, the electric motor is controlled so that the traveling power does not exceed the upper limit. And since a control device makes the upper limit of driving power small, so that the increase speed of driving power is large, driving power is suppressed with respect to the rapid increase request | requirement (traveling accelerator pedal suddenly etc.). Therefore, according to the present invention, power consumption during EV traveling can be reduced. In addition, it is possible to urge the driver to suppress a sudden increase in travel power demand (sudden depression of the accelerator pedal).

1 is a block diagram showing an overall configuration of an electric vehicle according to Embodiment 1 of the present invention. It is a functional block diagram which shows the specific structure of ECU shown in FIG. It is the figure which showed the relationship between the increase speed of driving power, and expansion power. It is the figure which showed the relationship between expansion time and the permission time when the upper limit of driving power is expanded to expansion power. It is the figure which showed an example of a mode that driving | running | working power and energy amount E changed. It is a flowchart for demonstrating the process sequence regarding the setting of expansion power. FIG. 6 is a functional block diagram showing a specific configuration of an ECU in the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
1 is a block diagram showing an overall configuration of an electric vehicle according to Embodiment 1 of the present invention. Referring to FIG. 1, electrically powered vehicle 10 includes a power storage device 12, a current sensor 14, a voltage sensor 16, a power control unit (hereinafter referred to as “PCU (Power Control Unit)”) 18, and a motor generator 20. Drive wheel 22, electronic control unit (hereinafter referred to as “ECU (Electronic Control Unit)”) 24, and accelerator opening sensor 26.

  The power storage device 12 is a rechargeable DC power source, and is constituted by a secondary battery such as lithium ion or nickel metal hydride. The power storage device 12 supplies power to the PCU 18 and stores regenerative power generated by the motor generator 20 when the vehicle is braked. Note that a large-capacity capacitor can also be used as the power storage device 12.

  Current sensor 14 detects current IB input / output to power storage device 12 and outputs the detected value to ECU 24. Voltage sensor 16 detects voltage VB of power storage device 12 and outputs the detected value to ECU 24.

  PCU 18 receives supply of electric power from power storage device 12 and drives motor generator 20 based on drive signal DRV received from ECU 24. Further, when the vehicle is braked, the PCU 18 converts the electric power generated by the motor generator 20 by receiving the kinetic energy from the drive wheels 22 and outputs the voltage to the power storage device 12. The PCU 18 is configured by a three-phase PWM inverter including switching elements for three phases, for example. Note that a boost converter may be provided between the three-phase PWM inverter and the power storage device 12.

  The motor generator 20 is a motor generator that can perform a power running operation and a regenerative operation, and is configured by, for example, a three-phase AC synchronous motor generator in which a permanent magnet is embedded in a rotor. The motor generator 20 is driven by the PCU 18 and generates the requested traveling power to drive the drive wheels 22. In addition, when the electric vehicle 10 is braked, the motor generator 20 receives the kinetic energy of the electric vehicle 10 from the drive wheels 22 and generates electric power.

  The accelerator opening sensor 26 detects the accelerator opening ACC corresponding to the amount of operation of the accelerator pedal by the driver, and outputs the detected value to the ECU 24.

  The ECU 24 controls the PCU 18 by software processing by executing a program stored in advance by a CPU (Central Processing Unit) and / or hardware processing by a dedicated electronic circuit. Specifically, the ECU 24 requests the required travel power (hereinafter simply referred to as “travel power”) based on various signals such as the accelerator travel ACC detected by the accelerator travel sensor 26 and the vehicle speed SV indicating the travel speed of the electric vehicle 10. Is also referred to as “.”. Then, ECU 24 generates a signal (for example, PWM (Pulse Width Modulation) signal) for driving motor generator 20 by PCU 18 based on the calculated traveling power, and uses the generated signal as drive signal DRV to PCU 18. Output.

  FIG. 2 is a functional block diagram showing a specific configuration of the ECU 24 shown in FIG. Referring to FIG. 2, ECU 24 includes a required travel power calculation unit 52, a temporary power up control unit 54, an enlarged power setting unit 56, and a motor generator control unit 58. The required travel power calculation unit 52 calculates the required travel power based on various signals such as the accelerator opening ACC and the vehicle speed SV detected by the accelerator opening sensor 26 (FIG. 1).

  The temporary power-up control unit 54 receives the travel power calculated by the required travel power calculation unit 52 and receives the set value of the expanded power Ppeak (described later) from the expanded power setting unit 56. Further, power temporary up control unit 54 calculates the power (corresponding to the actual traveling power) output from power storage device 12 based on current IB and voltage VB of power storage device 12. Then, when the traveling power exceeds the steady power Pbase indicating the upper limit of the traveling power that can be constantly output, the power temporary increase control unit 54 temporarily increases the upper limit of the traveling power from the steady power to the expanded power Ppeak.

  That is, steady power Pbase corresponds to the continuous rating of PCU 18 and motor generator 20. The enlarged power Ppeak corresponds to a short-time rating that can be output for a predetermined permission time Ttmp when the traveling power exceeds the steady power. The enlargement power Ppeak is set in an enlargement power setting unit 56 described later.

  When the running power exceeds the steady power Pbase, the power temporary increase control unit 54 falls within the range of the maximum energy amount Emax determined by the difference between the expanded power Ppeak and the steady power Pbase and the permission time Ttmp that can output the expanded power Ppeak. Manage driving power. When the energy amount E calculated by the arithmetic expression shown below reaches the maximum energy amount Emax, the power temporary increase control unit 54 limits the traveling power to the steady power Pbase. The maximum energy amount Emax and the energy amount E are calculated by the following equations.

Emax = (Ppeak-Pbase) × Ttmp (1)
E = ∫ (Pb−Pbase) dt, E ≧ 0 (2)
E <Emax: Pb * ≦ Ppeak (3)
E ≧ Emax: Pb * ≦ Pbase (4)
Here, Pb indicates the power output from the power storage device 12 (ie, traveling power), and Pb * indicates the allowable value of Pb (power that can be output from the power storage device 12).

  The enlargement power setting unit 56 sets the above enlargement power Ppeak. Specifically, when the traveling power exceeds the steady power Pbase, the expanded power setting unit 56 detects the increasing speed (inclination of increase) of the traveling power, and decreases the expanding power Ppeak as the increasing speed of the traveling power increases. .

  FIG. 3 is a diagram showing the relationship between the increasing speed of the traveling power and the expanded power Ppeak. Referring to FIG. 3, the larger the increase speed of the traveling power, the smaller the expansion power Ppeak is set. When the increase speed of the traveling power is 0, the expanded power Ppeak is the maximum power Pb_max that can be output by the power storage device 12. FIG. 3 shows a case where the increasing speed of the traveling power and the expansion power Ppeak are in a proportional relationship (negative slope). However, the relationship is not limited to the proportional relationship, for example, inversely proportional. The relationship may be

  FIG. 4 is a diagram showing the relationship between the expanded power Ppeak and the permission time Ttmp in which the upper limit of the traveling power is expanded to the expanded power Ppeak. Referring to FIG. 4, the expansion power Ppeak and the permission time Ttmp are in an inversely proportional relationship. That is, the maximum energy amount Emax that can be used after the traveling power exceeds the steady power Pbase is unchanged, and the maximum energy amount Emax that can be used does not change even if the expansion power Ppeak is changed according to the increasing speed of the traveling power. It is.

  Referring to FIG. 2 again, the expansion power setting unit 56 may set the expansion power Ppeak based on the accelerator opening ACC. That is, when the traveling power exceeds the steady power Pbase, the expanded power setting unit 56 may decrease the expanded power Ppeak as the increase speed of the accelerator opening ACC detected by the accelerator opening sensor 26 increases.

  The power temporary up control unit 54 receives the expansion power Ppeak from the expansion power setting unit 56. Then, when the traveling power exceeds the steady power Pbase, the power temporary increase control unit 54 temporarily increases the upper limit of the traveling power from the steady power to the expanded power Ppeak set by the expanded power setting unit 56.

  The motor generator control unit 58 calculates a drive signal DRV for driving the motor generator 20 by the PCU 18 based on the required travel power subjected to the upper limit process by the power temporary increase control unit 54 and the rotational speed MRN of the motor generator 20. To do. Then, motor generator controller 58 outputs the calculated drive signal DRV to PCU 18.

  FIG. 5 is a diagram showing an example of how the traveling power and the energy amount E change. Referring to FIG. 5, line k1 indicates traveling power (corresponding to the output power of power storage device 12), and line k2 indicates energy amount E calculated by the above equation (2).

  When the traveling power exceeds the steady power Pbase at time t3, the energy amount E increases based on the equation (2). Thereafter, the increasing speed of the traveling power, that is, the slope of the line k1 is detected, and the enlarged power Ppeak is changed according to the relationship shown in FIG. 3 based on the detection result.

  When energy amount E reaches maximum energy amount Emax at time t4, the allowable value of the output power of power storage device 12 is limited to the steady power Pbase or less based on equation (4). In FIG. 5, the allowable value of the output power of the power storage device 12 is limited to the steady power Pbase, so that the traveling power is limited to the steady power Pbase. Thereafter, when the traveling power starts to decrease at time t5, the energy amount E also decreases based on the equation (2).

  As described above, in the first embodiment, the larger the increasing speed of the traveling power, the smaller the expansion power Ppeak. As a result, the driving power is suppressed in response to a sudden increase in driving power (such as a sudden depression of the accelerator pedal), and the driver is prevented from requesting a rapid increase in driving power (abrupt depression of the accelerator pedal). It is intended to encourage.

  FIG. 6 is a flowchart for explaining a processing procedure regarding the setting of the expansion power Ppeak. Note that the processing of this flowchart is called from the main routine and executed repeatedly at regular time intervals or whenever a predetermined condition is satisfied.

  Referring to FIG. 6, accelerator opening sensor 26 (FIG. 1) detects accelerator opening ACC and outputs the detected value to ECU 24 (step S10). Next, the ECU 24 calculates the traveling power required for the electric vehicle 10 based on various signals such as the accelerator opening ACC and the vehicle speed SV (step S20). When the traveling power is calculated, the ECU 24 determines whether the motor generator 20 is in a power running operation or a regenerative operation (step S30). As an example, if the traveling power is a positive value, it is determined that the power running operation is being performed, and if the traveling power is a negative value, it is determined that the regenerative operation is being performed.

  If it is determined in step S30 that the power running operation is being performed (“power running” in step S30), the ECU 24 detects the increasing speed (inclination) of the traveling power (step S40). For example, the ECU 24 may calculate the increasing speed of the traveling power based on the difference between the traveling power calculated before a predetermined time (for example, one calculation cycle before) and the traveling power calculated at the time of the current calculation. it can. If it is determined in step S30 that the regeneration operation is being performed (“regeneration” in step S30), the process proceeds to step S50 without executing the process of step S40.

  Then, the ECU 24 sets the enlarged power Ppeak (step S50). Specifically, when it is determined in step S30 that the power running operation is being performed, the ECU 24 sets the enlarged power Ppeak according to the relationship shown in FIG. 3 based on the increasing speed of the traveling power detected in step S40. To do. When it is determined in step S30 that the regenerative operation is being performed, the ECU 24 sets the enlarged power Ppeak to a predetermined value (for example, Pb_max shown in FIG. 3).

  As described above, in the first embodiment, the larger the traveling power increase rate, the smaller the expansion power Ppeak, so that the traveling power in response to a rapid increase in traveling power (such as a sudden depression of the accelerator pedal). Is suppressed. Therefore, according to the first embodiment, power consumption during EV traveling can be reduced. In addition, the driver is encouraged to suppress a rapid increase in travel power (sudden depression of the accelerator pedal), and eco-driving can be promoted.

[Embodiment 2]
In the first embodiment, the larger the increasing speed of the traveling power, the smaller the expanded power Ppeak is. However, the traveling state of the electric vehicle 10 may be learned, and the expanded power Ppeak may be changed based on the learning result. .

  The overall configuration of the electric vehicle according to the second embodiment is the same as that of electric vehicle 10 according to the first embodiment shown in FIG.

  FIG. 7 is a functional block diagram showing a specific configuration of ECU 24A in the second embodiment. Referring to FIG. 7, ECU 24 </ b> A further includes learning unit 60 in the configuration of ECU 24 in the first embodiment shown in FIG. 2, and includes an expanded power setting unit 56 </ b> A instead of expanded power setting unit 56.

  Learning unit 60 learns the traveling state of electric vehicle 10 and outputs the learning result to enlarged power setting unit 56A. As an example, the learning unit 60 collects the frequency, time, and the like at which the traveling power reaches the expanded power Ppeak for each user and learns the tendency thereof.

  The enlarged power setting unit 56A changes the enlarged power Ppeak based on the learning result of the learning unit 60. As an example, the expanded power setting unit 56A decreases the expanded power Ppeak for a user whose traveling power reaches the expanded power Ppeak at a high frequency or time. As a result, a driver whose traveling power reaches the increased power Ppeak is frequently urged to suppress a rapid increase request for traveling power (sudden depression of the accelerator pedal).

  Note that the expansion power setting unit 56A may change the expansion power Ppeak based on the learning result of the learning unit 60 with respect to the setting of the expansion power Ppeak shown in FIG. 3, or the expansion power Ppeak shown in FIG. Regardless of the setting of Ppeak, the expansion power Ppeak may be set based on the learning result of the learning unit 60.

  As described above, in the second embodiment, the traveling state of the electric vehicle 10 is learned, and the expanded power Ppeak is changed based on the learning result. Therefore, according to the second embodiment, a driver whose traveling power reaches the expanded power Ppeak is frequently urged to suppress a rapid increase in traveling power demand (sudden depression of the accelerator pedal). It becomes possible.

  In each of the above embodiments, electric vehicle 10 may be a hybrid vehicle further equipped with an engine (not shown) as a power source. However, the present invention relates to control during EV travel in which the engine is stopped and travels. In a hybrid vehicle, for example, the present invention is applied to a case where EV travel is performed in a region where the operation of the engine is prohibited. Is.

  In the above, power storage device 12 corresponds to an example of “DC power supply” in the present invention, and motor generator 20 corresponds to an example of “electric motor” in the present invention. The ECUs 24 and 24A correspond to an embodiment of the “control device” in the present invention, and the accelerator opening sensor 26 corresponds to an embodiment of the “detection unit” in the present invention.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  DESCRIPTION OF SYMBOLS 10 Electric vehicle, 12 Electric power storage apparatus, 14 Current sensor, 16 Voltage sensor, 18 PCU, 20 Motor generator, 22 Driving wheel, 24, 24A ECU, 26 Accelerator opening degree sensor, 52 Required travel power calculation part, 54 Power temporary up control Unit, 56, 56A expansion power setting unit, 58 motor generator control unit, 60 learning unit.

Claims (6)

DC power supply,
An electric motor that receives electric power from the DC power source and generates the required traveling power;
A controller for controlling the electric motor so that the traveling power does not exceed an upper limit;
The said control apparatus is an electric vehicle which makes the said upper limit small, so that the increase speed of the said travel power is large. When the traveling power exceeds the steady power indicating the upper limit of the traveling power that can be output steadily, the control device temporarily increases the upper limit of the traveling power from the steady power to an expanded power that can be output for a predetermined permission time. Expanded
The upper limit is the expansion power,
2. The electric vehicle according to claim 1, wherein when the traveling power exceeds the steady power, the control device decreases the enlarged power as the increasing speed of the traveling power increases.   The control device further controls the electric motor within a range of a maximum energy amount determined by a difference between the enlarged power and the steady power and the permission time when the traveling power exceeds the steady power. The electric vehicle as described in.   When the traveling power exceeds the steady power, the control device is configured such that an energy amount obtained by integrating a value obtained by subtracting the steady power from the power supplied from the DC power source to the motor is the maximum energy amount. The electric vehicle according to claim 3, wherein the traveling power is limited to the steady power when reaching. It further comprises a detector that detects the accelerator opening related to the amount of operation of the accelerator pedal,
The travel power is calculated based on the accelerator opening detected by the detection unit,
5. The electric vehicle according to claim 1, wherein the control device decreases the upper limit as the rate of increase in the accelerator opening increases.   The electric vehicle according to any one of claims 1 to 5, wherein the control device learns a traveling situation and changes the upper limit based on a learning result.

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