JP2014125076A - Electric vehicle and control method for the same - Google Patents

Abstract

Torque compensation control is appropriately executed when shifting of a transmission is performed when traveling with a third rotating element of a differential gear fixed to be non-rotatable by a fixing device.
A torque compensation controller performs torque compensation so as to suppress fluctuations in output torque of an automatic transmission during a shift. Torque compensation control section 76 executes torque compensation by motor generators MG1 and MG2 so that brake Bcr does not slip when shifting is performed during both-drive EV traveling that operates with motor generators MG1 and MG2 by operating brake Bcr. .
[Selection] Figure 8

Description

  The present invention relates to an electric vehicle and an electric vehicle control method, and in particular, a first rotating element connected to a first electric motor, a second rotating element connected to a second electric motor, and a third rotating element. The present invention relates to an electric vehicle provided with a differential device constituted by the above and a transmission provided between a second rotating element and a drive shaft, and a control method therefor.

  Japanese Patent Laying-Open No. 2010-125938 (Patent Document 1) discloses a control device for an electric vehicle including the above-described differential and transmission. In this control device, torque that compensates for torque when the output torque of the stepped transmission unit temporarily drops during the torque phase of the stepped transmission unit (transmission device) to reduce the drop in the output torque. Phase compensation control is executed (see Patent Document 1).

JP 2010-125938 A JP 2008-265598 A

  In the electric vehicle as described above, a fixing device is provided on the third rotating element of the differential device, and the third rotating element is fixed to be non-rotatable by the fixing device, whereby both the first and second electric motors are provided. It is possible to perform electric motor traveling (EV traveling) using this driving force. When shifting of the transmission is performed under such traveling conditions, how the first and second motors share torque compensation control for compensating the output torque so as to suppress fluctuations in the output torque of the transmission. The above-mentioned patent document does not particularly examine whether to execute the process.

  The present invention has been made to solve such a problem, and an object thereof is to fix the third rotating element of the differential device in a non-rotatable manner by the fixing device in the electric vehicle including the differential device and the transmission. Thus, when the vehicle is running, torque compensation control when the transmission is shifted is appropriately executed.

  According to the present invention, the electric vehicle includes the first and second electric motors, the differential, the transmission, the fixing device, and the control device. The differential device includes a first rotating element connected to the first electric motor, a second rotating element connected to the second electric motor, and a third rotating element. The transmission is provided between the second rotating element and the drive shaft. The fixing device is provided to fix the third rotating element in a non-rotatable manner. The control device controls the first and second electric motors, the transmission, and the fixing device. The control device includes a drive control unit and a torque compensation control unit. The drive control unit controls the first and second electric motors, the fixing device, and the transmission so as to travel in a state where the third rotating element is fixed to be non-rotatable by the fixing device. The torque compensation control unit executes torque compensation so as to suppress fluctuations in the output torque of the transmission during a shift of the transmission. The torque compensation control unit prevents the third rotating element from rotating when the transmission is shifted when the third rotating element is fixed in a non-rotatable state by the fixing device. Torque compensation by the first and second motors is executed.

  Preferably, the torque compensation control unit prevents the third rotation element from rotating when the speed change of the transmission is performed when traveling with the third rotation element being non-rotatably fixed by the fixing device. The torque compensation by the second motor is executed while limiting the torque of the first motor.

  Preferably, the torque compensation control unit calculates a torque upper limit of the first electric motor based on the torque capacity of the fixing device, and is traveling in a state where the third rotating element is fixed to be non-rotatable by the fixing device. When the transmission is shifted, if the torque of the first motor including the compensation torque exceeds the upper limit of torque, torque compensation using only the second motor is executed.

  Preferably, the torque compensation control unit calculates a torque upper limit of the first electric motor based on the torque capacity of the fixing device, and is traveling in a state where the third rotating element is fixed to be non-rotatable by the fixing device. When the transmission is shifted, if the torque of the first motor including the compensation torque exceeds the torque upper limit, the torque of the first motor is limited to the torque upper limit.

  Preferably, the torque compensation control unit is configured to perform the shift of the transmission when the third rotation element is fixed in a non-rotatable manner by the fixing device and when the transmission is not performing the shift. Also increases the torque capacity of the fixing device.

  Preferably, the torque compensation control unit causes a shortage of torque capacity of the fixing device when the transmission is shifted when the third rotation element is fixed in a non-rotatable manner by the fixing device. If there is no torque capacity, the first and second motors during the shifting of the transmission device will have a higher overall efficiency indicating the total efficiency of the first and second motors than when the torque capacity is insufficient. Determine the operating point.

  More preferably, the torque compensation control unit is configured to set the first and second motors so that the overall efficiency during the shifting of the transmission is maximized based on the efficiency predetermined for each operating point for the first and second motors. Determine the operating point of the motor.

  Preferably, the fixing device is constituted by a hydraulic engagement brake. The torque capacity is determined based on the hydraulic pressure supplied to the hydraulic engagement brake.

  Preferably, the electric vehicle further includes an internal combustion engine. The internal combustion engine is connected to the third rotating element.

  According to the present invention, the control method is a control method for an electric vehicle. The electric vehicle includes first and second electric motors, a differential, a transmission, and a fixing device. The differential device includes a first rotating element connected to the first electric motor, a second rotating element connected to the second electric motor, and a third rotating element. The transmission is provided between the second rotating element and the drive shaft. The fixing device is provided to fix the third rotating element in a non-rotatable manner. The control method includes a step of determining whether or not the transmission is shifting, and a step of executing torque compensation so as to suppress fluctuations in the output torque of the transmission during the shifting of the transmission. The step of executing the torque compensation is to prevent the third rotating element from rotating when the transmission is shifted when the third rotating element is fixed in a non-rotatable state by the fixing device. Performing torque compensation by the first and second electric motors.

  Preferably, the step of executing the torque compensation includes the step of rotating the third rotating element when the speed change of the transmission is performed when traveling with the third rotating element fixed in a non-rotatable state by the fixing device. A step of executing torque compensation by the second electric motor while limiting the torque of the first electric motor so as not to occur.

  Preferably, the step of executing the torque compensation is the non-execution of the speed change of the speed change device when the speed change of the speed change device is performed when traveling with the third rotation element fixed in a non-rotatable state by the fixing device. Increasing the torque capacity of the fixing device over time.

  In the present invention, the third rotating element is prevented from rotating when the transmission is shifted when the third rotating element of the differential gear is traveling in a state where the third rotating element of the differential gear is non-rotatably fixed by the fixing device. In addition, torque compensation by the first and second electric motors is executed. Therefore, according to the present invention, torque compensation control at the time of shifting can be executed without slipping the fixing device.

1 is an overall configuration diagram of a hybrid vehicle shown as an example of an electric vehicle according to Embodiment 1 of the present invention. FIG. 2 shows main signals inputted to and outputted from the control device shown in FIG. It is the figure which showed the structure of the differential part and automatic transmission part which are shown in FIG. It is the figure which showed the engagement action | operation table | surface of the automatic transmission part shown in FIG. It is a collinear diagram of the speed change mechanism comprised by a differential part and an automatic transmission part. It is the figure which showed the efficiency of motor generator MG1. It is the figure which showed the efficiency of motor generator MG2. It is a functional block diagram of HV-ECU shown in FIG. It is a flowchart for demonstrating the process sequence of the torque compensation control at the time of double drive EV driving | running | working. It is a time chart which shows an example of the shift control performed during double drive EV driving | running | working. 12 is a flowchart for illustrating a processing procedure of torque compensation control during double-drive EV traveling 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]
(Configuration of electric vehicle)
FIG. 1 is an overall configuration diagram of a hybrid vehicle 10 shown as an example of an electric vehicle according to Embodiment 1 of the present invention. Referring to FIG. 1, hybrid vehicle 10 includes an engine 12, a differential unit 20, an automatic transmission unit 30, a differential gear device 42, and drive wheels 44. Hybrid vehicle 10 further includes an inverter 52, a power storage device 54, a charger 56, a power receiving unit 58, and a control device 60. The hybrid vehicle 10 is configured by, for example, an FF (front engine / front drive) system, but may be configured by another drive system.

  The engine 12 is an internal combustion engine, and is composed of, for example, a gasoline engine or a diesel engine. The engine 12 converts thermal energy generated by the combustion of fuel into kinetic energy of a moving element such as a piston or a rotor, and outputs the converted kinetic energy to the differential unit 20. For example, if the motion element is a piston and the motion is a reciprocating motion, the reciprocating motion is converted into a rotational motion via a so-called crank mechanism, and the kinetic energy of the piston is transmitted to the differential unit 20.

  The differential unit 20 is connected to the engine 12. As will be described later, the differential unit 20 includes a motor generator driven by an inverter 52, a power split device (differential device) that divides the output of the engine 12 into a transmission member to the automatic transmission unit 30 and a motor generator. including. The configuration of the differential unit 20 will be described in detail later.

  The automatic transmission unit 30 is connected to the differential unit 20, the rotational speed of the transmission member (the input shaft of the automatic transmission unit 30) connected to the differential unit 20, and the drive shaft connected to the differential gear device 42. The ratio (speed ratio) with the rotation speed of the output shaft of the automatic transmission unit 30 is configured to be changeable. In the first embodiment, the automatic transmission unit 30 is configured by a stepped transmission capable of changing the gear ratio stepwise, but may be configured by a continuously variable transmission. Good. The differential gear device 42 is connected to the output shaft of the automatic transmission unit 30 and transmits the power output from the automatic transmission unit 30 to the drive wheels 44. The configuration of the automatic transmission unit 30 will be described in detail later together with the differential unit 20.

  Inverter 52 is electrically connected to power storage device 54 and drives a motor generator included in differential unit 20 based on a control signal from control device 60. For example, the inverter 52 is configured by a bridge circuit including power semiconductor switching elements for three phases. Although not particularly illustrated, a voltage converter may be provided between inverter 52 and power storage device 54.

  The power storage device 54 is a rechargeable DC power supply, and typically includes a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The power storage device 54 stores power for traveling and supplies the stored power to the inverter 52. In addition, the power storage device 54 is supplied by a power source (not shown) outside the vehicle (hereinafter also referred to as “external power source”, and charging of the power storage device 54 by the external power source is also referred to as “external charging”) input from the power receiving unit 58. Charged. Further, power storage device 54 is also charged by receiving electric power generated by the motor generator of differential unit 20 from inverter 52. Note that the power storage device 54 may be configured by a power storage element such as an electric double layer capacitor instead of the secondary battery.

  Charger 56 is electrically connected between power storage device 54 and power receiving unit 58, and converts power input from power receiving unit 58 to the voltage level of power storage device 54 during external charging to charge power storage device 54. . The power receiving unit 58 receives power from the external power source and outputs it to the charger 56. The power receiving unit 58 may be a connector, a plug, or the like that is electrically connected to an external power source, or may be a coil, an antenna, or the like that receives power from the external power source in a contactless manner.

  Control device 60 includes an engine ECU (Electronic Control Unit) 62, MG-ECU 64, battery ECU 66, charging ECU 68, and HV-ECU 70. Each of these ECUs includes a CPU (Central Processing Unit), a storage device, an input / output buffer, etc. (all not shown), and executes various controls described later. Note that the control executed by each ECU is not limited to processing by software, and can be processed by dedicated hardware (electronic circuit). In the first embodiment, the control device 60 is configured by each of the ECUs described above, but the control device 60 may be configured by one ECU.

  The engine ECU 62 generates a throttle signal, an ignition signal, a fuel injection signal, and the like for driving the engine 12 based on an engine torque command received from the HV-ECU 70 and outputs the generated signals to the engine 12. MG-ECU 64 generates a control signal for controlling inverter 52 based on a command from HV-ECU 70, and outputs the generated control signal to inverter 52.

  Battery ECU 66 is also referred to as a state of charge (“SOC (State Of Charge)”) of power storage device 54 based on the voltage and current of power storage device 54 detected by a voltage sensor and a current sensor (not shown). 100% is represented by 0 to 100%), and the estimation result is output to the HV-ECU 70. Charging ECU 68 generates a control signal for controlling charger 56 based on a command from HV-ECU 70, and outputs the generated control signal to charger 56.

  The HV-ECU 70 receives detection signals from various sensors and generates various commands for controlling each device of the hybrid vehicle 10. As main control executed by the HV-ECU 70, the HV-ECU 70 controls the engine 12, the differential unit 20, and the automatic transmission unit 30 to a desired state based on the operation amount of the accelerator pedal, the vehicle speed, and the like. The traveling control for traveling is executed. Further, the HV-ECU 70 executes torque compensation control for executing torque compensation so as to suppress fluctuations in the output torque of the automatic transmission unit 30 during the shift of the automatic transmission unit 30. These controls will be described in detail later.

  FIG. 2 shows main signals inputted to and outputted from the control device 60 shown in FIG. Referring to FIG. 2, HV-ECU 70 detects a signal from a vehicle speed sensor that detects the speed of hybrid vehicle 10, a signal from an accelerator opening sensor that detects an operation amount of an accelerator pedal, and a rotation speed of engine 12. A signal from an engine speed sensor, a signal from an MG1 speed sensor that detects the speed of a motor generator MG1 (described later) included in the differential section 20, and a rotation of a motor generator MG2 (described later) included in the differential section 20 A signal is received from the MG2 rotational speed sensor that detects the number. Further, the HV-ECU 70 detects a signal from the output shaft rotational speed sensor that detects the rotational speed of the output shaft of the differential unit 20 (corresponding to the input shaft of the automatic transmission unit 30), and the crank angle of the engine 12. It further receives a signal from the engine crank angle sensor, a signal from an engine water temperature sensor that detects the temperature of the cooling water of the engine 12, and a signal from an intake air temperature sensor that detects the temperature of the air taken into the engine 12. Further, the HV-ECU 70 receives a signal from an outside air temperature sensor that detects an outside air temperature around the hybrid vehicle 10, a signal from a shift position sensor that detects a shift position indicated by a shift lever, and a power storage estimated by the battery ECU 66. A signal indicating the SOC of the device 54 is further received.

  The HV-ECU 70 generates, for example, an engine torque command Ter indicating the target of the output torque of the engine 12 based on the above signal and outputs the engine torque command Ter to the engine ECU 62. A throttle signal, an ignition signal, a fuel injection signal, and the like for driving the engine 12 are generated and output to the engine 12.

  The HV-ECU 70 generates torque commands Tmr1 and Tmr2 for driving the motor generators MG1 and MG2 of the differential unit 20 and outputs the torque commands Tmr1 and Tmr2 to the MG-ECU 64, and outputs a charging command Pac for driving the charger 56. It is generated and output to the charging ECU 68, and a hydraulic pressure command for driving the automatic transmission unit 30 is generated and output to a hydraulic pressure control unit (not shown). Further, the HV-ECU 70 stops the engine 12 and a brake Bcr (described later) capable of fixing the output shaft of the engine 12 so as not to rotate during execution of EV traveling using the motor generators MG1 and MG2 of the differential unit 20. A drive signal for driving is generated.

  The MG-ECU 64 that has received the torque commands Tmr1 and Tmr2 generates a signal PWI for controlling the inverter 52 so that the motor generators MG1 and MG2 generate a torque corresponding to the torque commands Tmr1 and Tmr2. Signal PWI is output to inverter 52. Further, the charging ECU 68 that has received the charging command Pac generates a signal PWC for controlling the charger 56 so that the electric power corresponding to the charging command Pac is charged in the power storage device 54, and the generated signal PWC is Output to charger 56.

(Configuration of differential unit and automatic transmission unit)
FIG. 3 is a diagram showing the configuration of the differential unit 20 and the automatic transmission unit 30 shown in FIG. Referring to FIG. 3, differential unit 20 includes motor generators MG <b> 1 and MG <b> 2 and power split device 24. Each of motor generators MG1 and MG2 is an AC rotating electric machine, and is constituted by, for example, a permanent magnet type synchronous motor including a rotor in which a permanent magnet is embedded. Motor generators MG1 and MG2 are driven by inverter 52 (FIG. 1).

  The power split device 24 is configured by a single pinion type planetary gear, and includes a sun gear S0 (first rotating element RE1), a pinion gear P0, a ring gear R0 (second rotating element RE2), and a carrier CA0 (third rotating element). Element RE3). The carrier CA0 of the third rotating element RE3 is connected to the input shaft 22, and supports the pinion gear P0 so that it can rotate and revolve. Sun gear S0 of first rotating element RE1 is coupled to the rotating shaft of motor generator MG1. The ring gear R0 of the second rotating element RE2 is connected to the transmission member 26 and is configured to mesh with the sun gear S0 via the pinion gear P0. The rotation shaft of motor generator MG2 is coupled to transmission member 26. That is, ring gear R0 of second rotating element RE2 is also coupled to the rotating shaft of motor generator MG2.

  Power split device 24 functions as a differential device when sun gear S0, carrier CA0, and ring gear R0 rotate relatively. The rotational speeds of the sun gear S0, the carrier CA0, and the ring gear R0 have a relationship of being connected by a straight line in the nomograph as described later (FIG. 5). Due to the differential function of the power split device 24, the power output from the engine 12 is split into the sun gear S0 and the ring gear R0. Motor generator MG1 operates as a generator by the power divided into sun gear S0, and the electric power generated by motor generator MG1 is supplied to motor generator MG2 or stored in power storage device 54 (FIG. 1). . The motor unit MG1 generates power using the power divided by the power split device 24, or the motor generator MG2 is driven using the power generated by the motor generator MG1, so that the differential unit 20 is continuously variable. Functions as a machine.

  The torque converter 14 is provided between the input shaft 22 connected to the carrier CA0 and the output shaft of the engine 12, and the brake Bcr is provided on the input shaft 22. The torque converter 14 is a fluid transmission device including a pump impeller coupled to the output shaft of the engine 12, a turbine runner coupled to the input shaft 22, a stator, and a one-way clutch.

  The brake Bcr can fix the carrier CA0 of the third rotating element RE3 in a non-rotatable manner by fixing the input shaft 22 in a non-rotatable state. The brake Bcr is a friction engagement device that operates by hydraulic pressure, and has a wet multi-plate type in which a plurality of stacked friction plates are pressed by hydraulic pressure, or one end of a band wound around the outer peripheral surface of a rotating drum. It is composed of a band brake that is tightened by hydraulic pressure. The brake Bcr may be configured as a so-called dog clutch type in order to reduce drag during traveling using the engine 12, or may be configured by an electric brake (such as an electromagnetic brake).

  The automatic transmission unit 30 includes single pinion type planetary gears 32 and 34, clutches C1 and C2, brakes B1 and B2, and a one-way clutch F1. Planetary gear 32 includes a sun gear S1, a pinion gear P1, a carrier CA1, and a ring gear R1. Planetary gear 34 includes a sun gear S2, a pinion gear P2, a carrier CA2, and a ring gear R2.

  Each of the clutches C1 and C2 and the brakes B1 and B2 is a friction engagement device that is operated by hydraulic pressure, and includes the above-described wet multi-plate type, band brake, or the like. The one-way clutch F1 supports the carrier CA1 and the ring gear R2 connected to each other so as to be rotatable in one direction and not rotatable in the other direction.

  In the automatic transmission unit 30, the engagement devices of the clutches C1, C2, the brakes B1, B2, and the one-way clutch F1 are engaged according to the engagement operation table shown in FIG. The fourth gear and the reverse gear are alternatively formed. In FIG. 4, “◯” indicates an engaged state, “(◯)” indicates that the engine is engaged during engine braking, and a blank indicates a released state. It should be noted that a neutral state (a state in which power transmission is interrupted) is formed by disengaging all the engagement devices of the clutches C1, C2 and the brakes B1, B2.

  Referring to FIG. 3 again, differential portion 20 and automatic transmission portion 30 are connected by transmission members 26 to 28. The output shaft 36 connected to the carrier CA2 of the planetary gear 34 is connected to the differential gear device 42.

  FIG. 5 is a collinear diagram of the speed change mechanism constituted by the differential portion 20 and the automatic speed change portion 30. Referring to FIG. 3 together with FIG. 5, the vertical line Y1 of the collinear diagram corresponding to the differential unit 20 indicates the rotational speed of the sun gear S0 (first rotating element RE1) of the power split device 24, that is, the motor generator. The rotation speed of MG1 is shown. The vertical line Y2 indicates the rotation speed of the carrier CA0 (third rotation element RE3) of the power split device 24, that is, the rotation speed of the engine 12. Vertical line Y3 indicates the rotational speed of ring gear R0 (second rotational element RE2) of power split device 24, that is, the rotational speed of motor generator MG2. The interval between the vertical lines Y1 to Y3 is determined according to the gear ratio of the power split device 24.

  The vertical line Y4 in the collinear diagram corresponding to the automatic transmission unit 30 indicates the rotational speed of the sun gear S2 of the planetary gear 34, and the vertical line Y5 indicates the carrier CA2 of the planetary gear 34 and the ring gear R1 of the planetary gear 32 connected to each other. Indicates the rotation speed. A vertical line Y6 indicates the rotational speed of the ring gear R2 of the planetary gear 34 and the carrier CA1 of the planetary gear 32 connected to each other, and a vertical line Y7 indicates the rotational speed of the sun gear S1 of the planetary gear 32. The interval between the vertical lines Y4 to Y7 is determined according to the gear ratio of the planetary gears 32 and 34.

  When the clutch C1 is engaged, the sun gear S2 of the planetary gear 34 is connected to the ring gear R0 of the differential section 20, and the sun gear S2 rotates at the same speed as the ring gear R0. When the clutch C2 is engaged, the carrier CA1 of the planetary gear 32 and the ring gear R2 of the planetary gear 34 are connected to the ring gear R0, and the carrier CA1 and the ring gear R2 rotate at the same speed as the ring gear R0. When the brake B1 is engaged, the rotation of the sun gear S1 is stopped, and when the brake B2 is engaged, the rotation of the carrier CA1 and the ring gear R2 is stopped.

  For example, as shown in the engagement operation table of FIG. 4, the clutch C1, the brake B2, and the one-way clutch F1 are engaged (the brake B2 is engaged only during engine braking, and the one-way clutch F1 is engaged only during driving) When the other clutches and brakes are released, the alignment chart of the automatic transmission unit 30 becomes a straight line (dotted line) indicated by “1st” (first gear). When the clutch C1 and the brake B1 are engaged and the other clutches and brakes are released, the nomographic chart of the automatic transmission unit 30 becomes a straight line (solid line) indicated by “2nd” (second speed gear stage). . Thus, in the automatic transmission unit 30, the clutches C1 and C2 and the brakes B1 and B2 are engaged or released according to the engagement operation table of FIG. And a neutral state can be formed.

  On the other hand, in differential unit 20, by appropriately controlling rotation of motor generators MG1 and MG2, the rotational speed of ring gear R0 with respect to a predetermined rotational speed (including zero) of engine 12 coupled to carrier CA0. That is, a continuously variable transmission capable of continuously changing the rotation speed of the output shaft of the differential section 20 is realized. By connecting the automatic transmission unit 30 to the differential unit 20 having such a continuously variable transmission function, the transmission ratio of the differential unit 20 can be reduced while the continuously variable transmission function of the differential unit 20 is provided. The loss of motor generators MG1, MG2 can be reduced.

  Here, in the first embodiment, the brake Bcr is provided on the input shaft 22 connected to the carrier CA0. Therefore, as shown in FIG. 5, the engine 12 is stopped and the carrier CA0 of the third rotating element RE3 is fixed to be non-rotatable by the brake Bcr, so that the torque of the motor generator MG1 is set to the ring gear R0 with the brake Bcr as a fulcrum. Can be communicated to. That is, by operating the brake Bcr, it is possible to perform EV traveling using both driving forces of the motor generators MG1 and MG2 (hereinafter, such EV traveling is performed by driving both the motor generators MG1 and MG2). This is also referred to as “both drive EV traveling” using force.)

(Explanation of double drive EV travel)
As exemplified in FIG. 5, when shifting up from the first gear to the second gear during double-drive EV traveling, the collinear diagram of the differential unit 20 and the automatic transmission unit 30 is indicated by a dotted line. Transition from the state to the state indicated by the solid line. Along with the shift up, the rotational speed of the input shaft of the automatic transmission unit 30, that is, the output shaft (ring gear R0) of the differential unit 20, decreases, and the rotational speeds of the motor generators MG1 and MG2 decrease. In order to make the output (power) constant before and after the upshift, the torques of motor generators MG1 and MG2 increase with the upshift.

  Thus, the operating points of motor generators MG1 and MG2 change due to the shift, but the efficiency of motor generators MG1 and MG2 changes depending on the operating point of motor generators MG1 and MG2. Therefore, in the first embodiment, the gear stage of automatic transmission unit 30 is selected so that the efficiency of motor generators MG1 and MG2 is optimized, and the operating point of motor generators MG1 and MG2 is determined.

  FIG. 6 is a diagram showing the efficiency of the motor generator MG1. FIG. 7 shows the efficiency of motor generator MG2. Referring to FIGS. 6 and 7, the horizontal axis indicates the rotation speed of the corresponding motor generator, and the vertical axis indicates the torque of the corresponding motor generator. The efficiency of motor generators MG1 and MG2 decreases in the low torque region or the low rotation region, and becomes good in the high power region of the medium torque and medium rotation region. The alternate long and short dash line indicates a constant power curve and indicates the power shared by the corresponding motor generator.

  Hereinafter, the selection method of the gear stage at the time of double drive EV traveling will be described by taking the selection of the first gear stage and the second gear stage as an example. When motor generator MG1 travels at the first speed gear stage, its rotational speed becomes N1A, and when it travels at the second speed gear stage, its rotational speed becomes N1B. Further, when motor generator MG2 travels at the first speed gear stage, its rotational speed becomes N2A, and when it travels at the second speed gear stage, its rotational speed becomes N2B. When traveling at the first speed gear stage, the operating points of the motor generators MG1 and MG2 are points a1 and a2, respectively, and when traveling at the second speed gear stage, the operating points of the motor generators MG1 and MG2 are points b1 and b2, respectively. .

  Based on the efficiency of motor generator MG1 at operating point a1 and the efficiency of motor generator MG2 at operating point a2, the total efficiency of motor generators MG1 and MG2 when traveling at the first gear is calculated. Further, based on the efficiency of motor generator MG1 at operating point b1 and the efficiency of motor generator MG2 at operating point b2, the total efficiency of motor generators MG1 and MG2 when traveling at the second gear is calculated. The overall efficiency of motor generators MG1 and MG2 when traveling at the first speed gear stage is compared with the overall efficiency of motor generators MG1 and MG2 when traveling at the second speed gear stage, and the gear stage having the higher efficiency is compared. Is selected.

  In the above description, the selection of the first speed gear stage and the second speed gear stage has been described as an example. However, the total efficiency of the motor generators MG1 and MG2 is calculated for each gear stage, and the gears having the highest efficiency are compared with each other. By selecting the stage, the optimum gear stage can be selected from the first to fourth gear stages. The gear stage is selected by further considering the efficiency of the automatic transmission unit 30 by comparing the value obtained by multiplying the overall efficiency of the motor generators MG1 and MG2 with the transmission efficiency of the automatic transmission unit 30 (which varies depending on the gear stage). You may make it do.

(Description of shift control)
The shift transition period of the automatic transmission unit 30 is roughly divided into a torque phase in which the torque sharing of the clutch and brake in the automatic transmission unit 30 changes and an inertia phase in which a rotation change follows the torque phase. Then, torque compensation control is executed in order to suppress fluctuations in the output torque of the automatic transmission unit 30 that may occur during a shift transition period composed of a torque phase and an inertia phase. That is, in the torque phase, the input torque of the automatic transmission unit 30 (the output torque of the differential unit 20) is increased in order to suppress the drop in the output torque of the automatic transmission unit 30, and in the inertia phase, In order to suppress fluctuations in the output torque, the input torque of the automatic transmission unit 30 (the output torque of the differential unit 20) is reduced.

  During both-drive EV running, torque generator control that is executed during this shift transition period can be executed by motor generators MG1 and MG2. As described above, the operating points of motor generators MG1 and MG2 are determined in consideration of their overall efficiencies, so basically even in the shift transition period, the efficiency of motor generators MG1 and MG2 is considered. It is preferable to execute torque compensation control using both motor generators MG1 and MG2.

  However, when the compensation torque shared by motor generator MG1 increases, the torque capacity of brake Bcr for transmitting the torque of motor generator MG1 to the transmission member to automatic transmission unit 30 may be insufficient. In particular, since the compensation torque increases as the speed change is performed in a shorter period, in such a case, there is a particular concern that the torque capacity of the brake Bcr is insufficient. If the torque capacity of the brake Bcr is insufficient, the brake Bcr slips and the compensation torque (torque increase) in the torque phase cannot be generated sufficiently.

  Therefore, in the first embodiment, torque compensation of motor generator MG1 is limited according to the torque capacity of brake Bcr. Specifically, for example, the torque capacity of the brake Bcr is estimated based on the hydraulic pressure supplied to the brake Bcr, and the torque upper limit of the motor generator MG1 is calculated based on the torque capacity of the brake Bcr. When the torque of motor generator MG1 including the compensation torque of torque compensation control exceeds the above torque upper limit, torque compensation control is executed using motor generator MG2. In this case, the torque compensation may be executed using only the motor generator MG2, or the torque of the motor generator MG1 is limited to the upper limit of the torque, and the shortage of compensation by the motor generator MG1 is compensated by the motor generator MG2. You may do it.

  FIG. 8 is a functional block diagram of HV-ECU 70 shown in FIG. Referring to FIG. 8, HV-ECU 70 includes a drive control unit 72, a shift control unit 74, a torque compensation control unit 76, and an MG efficiency map 78.

  The drive control unit 72 drives the motor generators MG1, MG2 torque commands Tmr1, Tmr2, the engine 12 engine torque command Ter, and the automatic transmission unit 30 to drive the hybrid vehicle 10 in a desired traveling state. Generate hydraulic commands.

  Here, during both-drive EV traveling, drive control unit 72 uses MG efficiency map 78 in which the efficiency of motor generators MG1 and MG2 is predetermined for each operating point, and the overall efficiency of motor generators MG1 and MG2 is the highest. And the operating points of the motor generators MG1 and MG2 are determined by the method described above. Then, drive control unit 72 generates a drive signal for driving brake Bcr, and generates torque commands Tmr1 and Tmr2 so that motor generators MG1 and MG2 operate at their operating points. Further, when the drive control unit 72 notifies the gear change control unit 74 of the gear stage and receives a shift command from the shift control unit 74, the drive control unit 72 generates a hydraulic pressure command for the automatic transmission unit 30 according to the shift command.

  The shift control unit 74 receives a gear change notification from the drive control unit 72, and generates a shift command for executing the shift of the automatic transmission unit 30 and outputs it to the drive control unit 72 when a shift is necessary. . The torque compensation control unit 76 executes the above-described torque compensation control during a shift. Here, when receiving a shift control start notification from the shift control unit 74, the torque compensation control unit 76 determines whether or not the torque capacity of the brake Bcr is insufficient due to torque compensation by the motor generator MG1, and the torque of the brake Bcr is determined. When the capacity is insufficient, torque compensation by the motor generator MG2 is executed while limiting the torque of the motor generator MG1 so that the brake Bcr does not slip. Hereinafter, it demonstrates concretely using a type | formula.

  The equations of motion of motor generators MG1, MG2 and engine 12 connected by power split device 24 are expressed as follows.

Im1 × (dω1 / dt) = Tm1 + ρ / (1 + ρ) × Tx (1)
Im2 × (dω2 / dt) = Tm2−Tp + 1 / (1 + ρ) × Tx (2)
Ie × (dωe / dt) = Te−Tx (3)
ωe = ρ / (1 + ρ) × ω1 + 1 / (1 + ρ) × ω2 (4)
Here, Im1, Im2, and Ie indicate the moments of inertia of the motor generators MG1, MG2, and the engine 12, respectively, and ω1, ω2, and ωe indicate the rotational speeds of the motor generators MG1, MG2, and the engine 12, respectively. Tm1, Tm2, and Te represent the torques of the motor generators MG1 and MG2 and the engine 12, respectively, and Tp represents the torque of the output shaft of the differential unit 20. Further, ρ represents the gear ratio of the power split device 24, and Tx corresponds to torque obtained by converting the running torque on the rotation shaft of the engine 12. Assuming that d * / dt = 0, when Tx is deleted, the following equation is obtained.

Tp = Tm2-1 / ρ × Tm1 = Tm2 + 1 / (1 + ρ) × Te (5)
Te = − (1 + ρ) / ρ × Tm1 (6)
Assuming that the torque capacity of the brake Bcr is Tbcr, the torque upper limit Tm1_lim of the motor generator MG1 that does not exceed the torque capacity of the brake Bcr is calculated using Expression (6) as follows.

Tm1_lim = −ρ / (1 + ρ) × Tbcr (7)
When the torque command Tmr1 of the motor generator MG1 including the compensation torque during the shift exceeds the torque upper limit Tm1_lim, torque compensation is executed using the motor generator MG2.

  As described above, when the torque command Tmr1 exceeds the torque upper limit Tm1_lim, torque compensation may be executed using only the motor generator MG2, and in the equation (5), the torque Tm1 is changed to the torque upper limit Tm1_lim. The torque of the motor generator MG2 including the compensation torque may be calculated by limiting the torque Tp to include the compensation torque during the shift.

  When the torque of motor generator MG1 does not exceed torque upper limit Tm1_lim, torque compensation control unit 76 uses MG efficiency map 78 to satisfy the relationship of equation (5) while maintaining the overall efficiency of motor generators MG1 and MG2. The torque of motor generators MG1 and MG2 may be determined so that is optimal. In this case, the overall efficiency of motor generators MG1 and MG2 is higher than when the torque capacity of brake Bcr is insufficient and the torque of motor generator MG1 exceeds torque upper limit Tm1_lim.

  FIG. 9 is a flowchart for explaining a processing procedure of torque compensation control during double-drive EV traveling. Note that each step in the flowchart is realized by a program stored in advance in the HV-ECU 70 being called from the main routine and executed in response to the establishment of a predetermined cycle or a predetermined condition. Alternatively, processing can be realized by constructing dedicated hardware (electronic circuit) for all or some of the steps.

  Referring to FIG. 9, HV-ECU 70 determines whether or not brake Bcr is in an engaged state (step S10). That is, here, it is determined whether or not the double drive EV traveling is in progress. If it is determined that brake Bcr is in the released state (NO in step S10), the process proceeds to step S90.

  If it is determined in step S10 that the brake Bcr is in the engaged state (YES in step S10), the HV-ECU 70 determines whether or not the shift control is being performed (step S20). When the gear is not being changed (NO in step S20), the process proceeds to step S90.

  If it is determined in step S20 that the shift control is being performed (YES in step S20), HV-ECU 70 estimates the torque capacity of brake Bcr (step S30). The torque capacity of the brake Bcr is estimated based on, for example, the hydraulic pressure supplied to the brake Bcr. When the brake Bcr is configured by an electric brake such as an electromagnetic brake, the torque capacity may be estimated based on the power supplied to the brake Bcr.

  Next, the HV-ECU 70 calculates the torque upper limit Tm1_lim of the motor generator MG1 based on the torque capacity of the brake Bcr estimated in step S30 using the above equation (7) (step S40). Further, the HV-ECU 70 calculates the torque Tm1 of the motor generator MG1 during the shift including the torque compensation (step S50). The torque Tm1 of the motor generator MG1 including the compensation torque is calculated using the formula (5) based on the torque Tp including the compensation torque and taking into account the efficiency of the motor generators MG1 and MG2.

  Then, the HV-ECU 70 determines whether or not the torque Tm1 calculated in step S50 is larger than the torque upper limit Tm1_lim calculated in step S40 (step S60). If it is determined that torque Tm1 is greater than torque upper limit Tm1_lim (YES in step S60), HV-ECU 70 limits torque compensation by motor generator MG1 and executes torque compensation by motor generator MG2 (step S70). As described above, the torque compensation by the motor generator MG2 may be performed using only the motor generator MG2, or the torque of the motor generator MG1 is set to the torque upper limit Tm1_lim, and the shortage of the motor generator MG1 is set as the motor generator. You may make it supplement with MG2.

  If it is determined in step S60 that torque Tm1 is equal to or lower than torque upper limit Tm1_lim (NO in step S60), HV-ECU 70 permits torque compensation by motor generator MG1 (step S80). Specifically, based on the torque Tp including the compensation torque, torque compensation is executed by the motor generators MG1 and MG2 based on the above equation (5).

  FIG. 10 is a time chart showing an example of the shift control executed during the double drive EV travel. Referring to FIG. 10, when the shift control is started at time t1, it is determined whether or not torque Tm1 of motor generator MG1 including the compensation torque exceeds torque upper limit Tm1_lim. Here, it is determined that torque Tm1 exceeds torque upper limit Tm1_lim, and torque compensation is performed only by motor generator MG2.

  At time t2, the torque phase starts and the torque of motor generator MG2 increases (torque compensation control) in order to suppress the drop in output torque (AT output torque) of automatic transmission unit 30. That is, the input torque (AT input torque) of the automatic transmission unit 30 is increased, thereby suppressing the drop of the AT output torque.

  When the torque phase ends and the inertia phase starts at time t3, the rotational speeds of motor generators MG1 and MG2 change. At this time, the torque of motor generator MG2 is reduced in order to suppress fluctuations in the AT output torque due to rotation changes. That is, the input torque (AT input torque) of the automatic transmission unit 30 is reduced, thereby suppressing the fluctuation of the AT output torque.

  In FIG. 10, torque compensation control is executed only by motor generator MG2, so that after the shift control is completed at time t5, the motor generator is directed toward an operating point that optimizes the overall efficiency of motor generators MG1 and MG2. The operating points (torques) of MG1 and MG2 transition.

  As described above, in the first embodiment, when a shift is performed during the two-drive EV traveling with the brake Bcr activated, the motor is used to prevent the brake Bcr from slipping when the torque capacity of the brake Bcr is insufficient. Torque compensation by the motor generator MG2 is executed while limiting the torque of the generator MG1. Thereby, torque compensation is executed within the range of the torque capacity of the brake Bcr. Therefore, according to the first embodiment, torque compensation control at the time of shifting can be executed without slipping the brake Bcr.

  In Embodiment 1, when the torque capacity of brake Bcr is not insufficient, torques (including compensation torque) of motor generators MG1 and MG2 are optimized so that the overall efficiency of motor generators MG1 and MG2 is optimized. It is determined. Therefore, according to the first embodiment, the efficiency of motor generators MG1, MG2 is kept good even during a shift.

[Embodiment 2]
In the second embodiment, when shifting is performed during EV driving, if the torque capacity of the brake Bcr is insufficient, the torque capacity of the brake Bcr is increased so that the brake Bcr does not slip.

  The overall configuration of the electric vehicle according to the second embodiment is the same as that of the electric vehicle (hybrid vehicle 10) according to the first embodiment shown in FIG. The configurations of the differential unit and the automatic transmission unit in the second embodiment are also the same as those of the differential unit 20 and the automatic transmission unit 30 in the first embodiment shown in FIG.

  FIG. 11 is a flowchart for illustrating a processing procedure of torque compensation control during double-drive EV traveling in the second embodiment. Referring to FIG. 11, this flowchart includes step S85 in place of steps S70 and S80 in the flowchart shown in FIG.

  That is, if it is determined in step S60 that torque Tm1 is greater than torque upper limit Tm1_lim (YES in step S60), HV-ECU 70 increases the torque capacity of brake Bcr (step S85). Specifically, the HV-ECU 70 increases the torque capacity of the brake Bcr by increasing the hydraulic pressure supplied to the brake Bcr.

  On the other hand, if it is determined in step S60 that torque Tm1 is equal to or lower than torque upper limit Tm1_lim (NO in step S60), HV-ECU 70 proceeds to step S90 without increasing the torque capacity of brake Bcr.

  In the second embodiment, when shifting is performed during EV driving, if the torque capacity of the brake Bcr is insufficient, the torque capacity of the brake Bcr is increased so that the brake Bcr does not slip. Therefore, according to the second embodiment, torque compensation control at the time of shifting can be executed without slipping the brake Bcr.

  In the above embodiment, hybrid vehicle 10 is provided with charger 56 and power receiving unit 58 for charging power storage device 54 with an external power source. However, the present invention provides charger 56 and power receiving unit. The present invention can also be applied to a vehicle without 58.

  In the above embodiment, the electric vehicle is a hybrid vehicle equipped with the engine 12. However, the scope of application of the present invention is not limited to the hybrid vehicle as described above. It can also include an automobile and a fuel cell vehicle further equipped with a fuel cell as an energy source.

  In the above, motor generators MG1 and MG2 correspond to one embodiment of “first electric motor” and “second electric motor” in the present invention, respectively, and power split device 24 uses “differential device” in the present invention. Corresponds to an embodiment of "." Automatic transmission unit 30 corresponds to an embodiment of “transmission device” in the present invention, and brake Bcr corresponds to an embodiment of “fixing device” 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 Hybrid vehicle, 12 Engine, 14 Torque converter, 20 Differential part, 22 Input shaft, 24 Power split device, 26-28 Transmission member, 30 Automatic transmission part, 32, 34 Planetary gear, 36 Output shaft, 42 Differential gear apparatus , 44 drive wheel, 52 inverter, 54 power storage device, 56 charger, 58 power receiving unit, 60 control unit, 62 engine ECU, 64 MG-ECU, 66 battery ECU, 68 charge ECU, 70 HV-ECU, 72 drive control unit 74 Transmission control unit, 76 Torque compensation control unit, 78 MG efficiency map, Bcr, B1, B2 brake, S0-S2 sun gear, P0-P2 pinion gear, CA0-CA2 carrier, R0-R2 ring gear, C1, C2 clutch, F1 One-way clutch, RE1-RE3 rotating element.

Claims (12)

First and second electric motors;
A differential constituted by a first rotating element coupled to the first electric motor, a second rotating element coupled to the second electric motor, and a third rotating element;
A transmission provided between the second rotating element and the drive shaft;
A fixing device for fixing the third rotating element so as not to rotate;
A control device for controlling the first and second electric motors, the transmission, and the fixing device;
The control device includes:
A drive control unit that controls the first and second electric motors, the fixing device, and the transmission so as to travel in a state in which the third rotating element is fixed to be non-rotatable by the fixing device;
A torque compensation control unit that performs torque compensation so as to suppress fluctuations in the output torque of the transmission during a shift of the transmission,
The torque compensation control unit is configured to rotate the third rotation element when the transmission is shifted when the third rotation element is fixed in a non-rotatable state by the fixing device. An electric vehicle that performs torque compensation by the first and second electric motors so as not to occur.   The torque compensation control unit is configured to rotate the third rotation element when the transmission is shifted when the third rotation element is fixed in a non-rotatable state by the fixing device. 2. The electric vehicle according to claim 1, wherein torque compensation by the second electric motor is executed while limiting a torque of the first electric motor so as not to occur.   The torque compensation controller calculates an upper torque limit of the first electric motor based on a torque capacity of the fixing device, and travels in a state where the third rotating element is fixed to be non-rotatable by the fixing device. When the shift of the transmission device is performed in a case where the torque of the first motor including the compensation torque exceeds the torque upper limit, torque compensation using only the second motor is executed. Item 4. The electric vehicle according to Item 1.   The torque compensation controller calculates an upper torque limit of the first electric motor based on a torque capacity of the fixing device, and travels in a state where the third rotating element is fixed to be non-rotatable by the fixing device. When the shift of the transmission is performed in a case where the torque of the first motor including the compensation torque exceeds the torque upper limit, the torque of the first motor is limited to the torque upper limit. Item 4. The electric vehicle according to Item 1.   The torque compensation control unit does not execute the shift of the transmission when the shift of the transmission is performed while the third rotation element is fixed in a non-rotatable state by the fixing device. The electric vehicle according to claim 1, wherein the torque capacity of the fixing device is increased more than the time.   The torque compensation control unit may have a shortage of torque capacity of the fixing device when the transmission is shifted when the third rotation element is fixed in a non-rotatable manner by the fixing device. If the torque capacity does not occur, the first efficiency during the shift of the transmission is increased so that the overall efficiency indicating the total efficiency of the first and second motors is higher than when the torque capacity is insufficient. The electric vehicle according to claim 1, wherein an operating point of the second electric motor is determined.   The torque compensation control unit is configured to control the first and second motors so that the overall efficiency during shifting of the transmission is maximized based on the efficiency predetermined for each operating point of the first and second motors. The electric vehicle according to claim 6, wherein an operating point of the two electric motors is determined. The fixing device is constituted by a hydraulic engagement brake,
The electric vehicle according to claim 1, wherein the torque capacity is determined based on a hydraulic pressure supplied to the hydraulic engagement brake.   The electric vehicle according to claim 1, further comprising an internal combustion engine coupled to the third rotating element. An electric vehicle control method comprising:
The electric vehicle is
First and second electric motors;
A differential constituted by a first rotating element coupled to the first electric motor, a second rotating element coupled to the second electric motor, and a third rotating element;
A transmission provided between the second rotating element and the drive shaft;
A fixing device for fixing the third rotating element to be non-rotatable,
The control method is:
Determining whether or not the transmission is shifting;
Executing torque compensation so as to suppress fluctuations in output torque of the transmission during shifting of the transmission,
The step of executing the torque compensation includes the step of performing the third rotation element when a shift of the transmission is performed when the third rotation element is fixed in a non-rotatable state by the fixing device. A method for controlling an electric vehicle, comprising the step of executing torque compensation by the first and second electric motors so that the motor does not rotate.   The step of executing the torque compensation includes the step of performing the third rotation element when a shift of the transmission is performed when the third rotation element is fixed in a non-rotatable state by the fixing device. The method for controlling an electric vehicle according to claim 10, further comprising: executing torque compensation by the second electric motor while limiting the torque of the first electric motor so that the motor does not rotate.   The step of executing the torque compensation includes the step of changing the speed of the transmission when the speed change of the speed change device is performed while the third rotation element is fixed in a non-rotatable state by the fixing device. The method for controlling an electric vehicle according to claim 10, comprising a step of increasing a torque capacity of the fixing device as compared with a non-execution time.

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