Control device of electric vehicle

Abstract

To enable execution of effective magnetic force change control while reducing slip loss during automatic shift.SOLUTION: Provided is a control device of an electric vehicle 1 including an automatic transmission 8 in between a drive wheel 4R and a drive motor 3 in which a magnetic pole of a rotor 33 is configured by a magnetic force variable magnet 35. When magnetic force change control of changing a magnetic force of the magnetic force variable magnet 35 is performed during a gear change period of the automatic transmission 8, magnetic force change control is performed during a period of an inertia phase subsequent to a period of a torque phase in a gear change period of the automatic transmission 8.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The disclosed technology relates to a control device for an electric vehicle capable of traveling using electric power, such as an electric vehicle or a hybrid vehicle.

Background Art

[0002] Patent Document 1 discloses a hybrid vehicle equipped with a permanent magnet synchronous drive motor. In this drive motor, a magnetic force variable magnet whose magnetic force can be variably increased or decreased is used for the permanent magnet installed on the rotor.

[0003] When changing the magnetic force of the magnetic force variable magnet, a large magnetization current (so-called d-axis current) is applied to the coil of the stator of the drive motor. As a result, during the rotation of the drive motor, it interferes with the drive current (so-called q-axis current) and the torque fluctuates. That is, the d-axis current is a component orthogonal to the q-axis current that generates torque. Therefore, although the large current itself is not output as torque, the torque fluctuates by interfering with the q-axis current.

[0004] Generally, the engagement torque for engaging the clutch provided between the drive motor and the drive wheels is set higher than the required torque for which output is required so that the clutch is completely engaged. Therefore, there is a concern that the fluctuating torque is directly transmitted to the drive wheels, causing a torque shock to the traveling vehicle and giving the driver a sense of discomfort.

[0005] In order to suppress such a torque shock, it is conceivable to use a transmission installed between the drive motor and the drive wheels. That is, even if a high torque is output from the drive motor, if the clutch of the transmission is slipped, the torque transmitted to the drive wheels can be reduced, so that the torque shock can be alleviated.

[0006] However, when the clutch slips, a phenomenon occurs where the rotation of the drive motor rapidly increases (so-called "runaway"). If such a runaway phenomenon is not quickly eliminated, there is a concern that the clutch may be damaged by the frictional heat due to the slip.

[0007] Therefore, the present inventors have previously proposed a technique for quickly eliminating the runaway of the drive motor associated with such clutch slip (Patent Document 2).

[0008] That technique generally switches from torque control that controls the torque required for output to power control that controls the power output, when slip occurs in the clutch by increasing the magnetic force, with the target being the required torque. Thereby, together with the output torque, it becomes possible to converge the rotational speed, and the runaway of the drive motor can be quickly eliminated.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] The control for changing the magnetic force of the magnet with variable magnetic force (magnetic force change control) was assumed to be executed while avoiding the timing when the vehicle shifts gears, from the viewpoint of suppressing the influence of disturbances. That is, the technique of Patent Document 2 described above was also premised on the off - target use of a transmission that was not shifting gears.

[0011] However, it has been found that as the optimization of motor efficiency progresses, depending on the conditions, the frequency of the magnetic force change control may significantly exceed the assumption. For example, during driving in the WLTC mode, the frequency of the magnetic force change control can be several times that of gear shifting.

[0012] Therefore, it is also assumed that there are cases where magnetic force change control must be executed during gear shifting of the vehicle. During gear shifting, a torque shock may occur accordingly. Moreover, when the torque shock of the magnetic force change control is added, there is a concern that it will not only give the driver a sense of discomfort but also cause unnecessary uneasiness such as gear shifting troubles.

[0013] On the other hand, during gear shifting, there is a period when the clutch is slipping. The inventors have found that if this is utilized effectively, it is possible to reduce slip loss and the like.

[0014] Therefore, this specification discloses a technique that enables magnetic force change control to be executed while suppressing torque shock during automatic gear shifting of a vehicle and can also reduce slip loss.

Means for Solving the Problems

[0015] The disclosed technique relates to a control device for an electric vehicle that is equipped with a drive motor in which the magnetic poles of a rotor are configured by a magnetically variable magnet capable of changing magnetic force, and an automatic transmission that is disposed between the drive motor and drive wheels and includes a plurality of clutches, and is capable of traveling using electric power.

[0016] In the case of shift-time magnetic force change control in which the control device executes magnetic force change control for changing the magnetic force of the magnetically variable magnet within the shift period of the automatic transmission, during the period of the automatic transmission's shift period that follows the period of the torque phase in which torque transmission is switched from a predetermined first clutch before shifting to a predetermined second clutch after shifting, and within the period of the inertia phase in which the rotation speed is switched to the rotation speed corresponding to the gear ratio from the first clutch to the second clutch, the magnetic force change control is executed.

[0017] That is, according to this control device, magnetic force change control for changing the magnetic force of the magnet with variable magnetic force is also executed during the gear shift period of the automatic transmission. However, in the case of the magnetic force change control during gear shifting, the magnetic force change control is executed within the inertia phase period following the torque phase period in which the torque transmission is switched, during the gear shift period of the automatic transmission.

[0018] Among the gear shift periods of the automatic transmission, the periods during which magnetic force change control can be executed include the torque phase and the inertia phase. However, during the torque phase period, both the first clutch and the second clutch are slipping, and the torque transmission is switched while holding the input torque by torque control. Therefore, from the viewpoint of control stability, it is not preferable to repeatedly execute the magnetic force change control.

[0019] On the other hand, during the inertia phase period, the switching from the first clutch to the second clutch is substantially completed, and the second clutch is slipping with the engagement torque reduced to near the transmission torque. By executing the rotational speed feedback control using the slipping second clutch, the minute slip control can be easily executed. Since the slip associated with gear shifting is utilized, the slip loss associated with the minute slip control can be reduced.

[0020] It is also possible to start the magnetic force change control at the initial stage of the inertia phase.

[0021] If that is done, by adding the torque generated along with the magnetic force change control to the second clutch that is slipping during the torque phase, the slip can be increased. Thereby, the synchronization of the rotational speed is promoted. It becomes possible to shorten the inertia phase period and the gear shift period can be shortened. If the inertia phase period is shortened, the slip loss is further reduced.

[0022] Specifically, the control device may be configured as follows.

[0023] When the electric vehicle is running, torque control is performed to control the motor torque output by the drive motor so as to match the required torque required by the drive wheels, and clutch full engagement control is executed to make the engagement torque of the engaged clutch higher than the transmission torque.

[0024] And, in the case of non-shifting magnetic force change control in which the magnetic force change control is executed outside the shift period of the automatic transmission, by lowering the engagement torque to near the transmission torque instead of the clutch full engagement control, the clutch is slipped, and rotation speed feedback control based on the differential rotation speed between the input side and the output side of the clutch is executed, so that minute slip control for slightly slipping the clutch at a predetermined rotation speed immediately before the magnetic force change control is executed.

[0025] On the other hand, in the case of magnetic force change control during shifting, the minute slip control is executed by performing the rotation speed feedback control using the second clutch that is slipping during the inertia phase.

[0026] That is, according to this control device, magnetic force change control for changing the magnetic force of the magnet with variable magnetic force can be executed regardless of the shift of the automatic transmission. Therefore, the motor efficiency is increased. Moreover, torque shock can be suppressed and slip loss can also be reduced. Thereby, driving comfort and fuel efficiency (electricity cost) can be improved.

[0027] When the shift of the automatic transmission is a downshift, the command value of the torque control is offset so that the torque fluctuation associated with the magnetic force change control during shifting occurs on the plus side with respect to the actual torque output to the drive wheels, and when the shift of the automatic transmission is an upshift, the command value of the torque control may be offset so that the torque fluctuation occurs on the minus side with respect to the actual torque.

[0028] If this is done, it is possible to add torque generated with the magnetic force change control to the second clutch that is slipping during the torque phase without wasting the torque. The slip increases and the synchronization of the rotational speed is promoted. It becomes possible to further shorten the period of the inertia phase, and the shift period can be shortened. If the period of the inertia phase is shortened, the slip loss is further reduced.

Effect of the Invention

[0029] According to the disclosed technology, magnetic force change control can be executed while effectively suppressing torque shock even during a shift of a vehicle. Therefore, since magnetic force change control can be performed without considering the shift, the motor efficiency is increased. Further, slip loss can also be reduced. Thereby, the fuel efficiency (electricity cost) of the electric vehicle can be improved.

Brief Description of the Drawings

[0030]

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Embodiments for Carrying Out the Invention

[0031] Hereinafter, the disclosed technology will be described. However, the following description is merely illustrative in nature.

[0032] <Electric Vehicle> FIG. 1 shows an automobile 1 (an example of an electric vehicle) to which the disclosed technology is applied. This automobile 1 is a hybrid vehicle capable of traveling using electric power. An engine 2 and a drive motor 3 are mounted on the drive source of the automobile 1. These cooperate to drive two wheels (drive wheels 4R) that are symmetrically located among the four wheels 4F, 4F, 4R, 4R. Thereby, the automobile 1 travels. Note that the automobile 1 may be an electric vehicle equipped only with the drive motor 3. The automobile 1 may also be four-wheel drive.

[0033] In the case of this automobile 1, the engine 2 is disposed on the front side of the vehicle body, and the drive wheels 4R are disposed on the rear side of the vehicle body. That is, this automobile 1 is a so-called FR vehicle. Further, in the case of this automobile 1, as the drive source, the engine 2 is the main body rather than the drive motor 3, and the drive motor 3 is used in a form that assists the drive of the engine 2 (so-called mild hybrid). The drive motor 3 is also used not only as a drive source but also as a generator during regeneration.

[0034] In addition to the engine 2 and the drive motor 3, the vehicle 1 is equipped with, as devices in the drive system, a relay clutch 5, an inverter 6, an automatic transmission 8, a differential gear 9, a battery 10, etc. The vehicle 1 is also equipped with, as devices in the control system, an engine control unit (ECU) 20, a motor control unit (MCU) 21, a transmission control unit (TCU) 22, a brake control unit (BCU) 23, a comprehensive control unit (GCU) 24, etc. An engine rotation sensor 50, a motor rotation sensor 51, a current sensor 52, a magnetic sensor 53, an accelerator sensor 54, a transmission sensor 55, etc. are also installed in the vehicle 1 along with the devices in the control system.

[0035] (Devices in the drive system) The engine 2 is an internal combustion engine that burns, for example, gasoline as fuel. The engine 2 is also a so-called four-cycle engine that generates rotational power by repeating each cycle of intake, compression, expansion, and exhaust. There are various types and forms of the engine 2, such as a diesel engine, but in the disclosed technology, the type and form of the engine are not particularly limited.

[0036] In this vehicle 1, the engine 2 is arranged at approximately the center in the vehicle width direction with the output shaft for outputting rotational power facing in the longitudinal direction of the vehicle body. The vehicle 1 is equipped with various devices and mechanisms associated with the engine 2, such as an intake system, an exhaust system, and a fuel supply system, but the illustration and description of these are omitted.

[0037] The drive motor 3 is arranged in series behind the engine 2 via the relay clutch 5. The drive motor 3 is a permanent magnet type synchronous motor driven by three-phase alternating current. As shown schematically in Figure 2, the drive motor 3 is generally composed of a motor case 31, a shaft 32, a rotor 33, a stator 34, etc.

[0038] The motor case 31 is a container having a cylindrical space with its front end face and rear end face sealed, and is fixed to the vehicle body of the automobile 1. The rotor 33 and the stator 34 are housed in the motor case 31. The shaft 32 is rotatably supported by the motor case 31 with its front end portion and rear end portion protruding from the motor case 31 respectively.

[0039] An intermediate clutch 5 is installed so as to be interposed between the front end portion of the shaft 32 and the output shaft of the engine 2. The intermediate clutch 5 is configured to be switchable between a state where the output shaft of the engine 2 and the shaft 32 are connected (engaged state) and a state where the output shaft of the engine 2 and the shaft 32 are separated (disengaged state).

[0040] The rear end portion of the shaft 32 is connected to the input shaft 80 of the automatic transmission 8. A second intermediate clutch may be provided between the shaft 32 and the input shaft 80 of the automatic transmission 8.

[0041] The rotor 33 is a columnar member formed by laminating a plurality of metal plates having a shaft hole at the center. By fixing the intermediate portion of the shaft 32 to the shaft hole of the rotor 33, the rotor 33 is integrated with the shaft 32.

[0042] Magnets 35 are installed over the entire outer peripheral portion of the rotor 33. The magnets 35 are configured such that different magnetic poles, that is, S poles and N poles, are arranged alternately at equal intervals in the circumferential direction. The magnets 35 may be composed of a single cylindrical magnet having a plurality of magnetic poles, or may be composed of a plurality of arc-shaped magnets constituting each magnetic pole.

[0043] In this drive motor 3, further, the magnet 35 is configured such that the magnitude of the magnetic force can be variably increased or decreased (magnetic force variable magnet 35). Usually, for this type of drive motor 3, a magnet (permanent magnet) having a large coercive force (demagnetizing force) and capable of holding the magnetic force over a long period is used. In this drive motor 3, a permanent magnet with a small holding force is used as the magnetic force variable magnet 35 so that the magnetic force can be changed relatively easily.

[0044] Permanent magnets include various types such as ferrite magnets, neodymium magnets, samarium cobalt magnets, and alnico magnets, and their holding forces also vary. The types and materials of the magnetically variable magnet 35 can be selected according to the specifications and are not particularly limited. Also, it is not necessary for all magnets to be the magnetically variable magnet 35, and permanent magnets may be included.

[0045] A cylindrical stator 34 is installed around the rotor 33 with a slight gap (gap) therebetween (inner rotor type). The stator 34 has a stator core 34a composed of a plurality of laminated metal plates and a plurality of coils 36 formed by winding electric wires around the stator core 34a.

[0046] The stator core 34a is provided with a plurality of teeth 34b that radially project inward, and a plurality of coils 36 are formed by winding electric wires around these teeth 34b in a predetermined order. These coils 36 constitute a three-phase coil group consisting of a U-phase, a V-phase, and a W-phase. Note that the slot combination of the drive motor 3 is designed according to the specifications.

[0047] To energize each phase of the coil group, connection cables 36a are led out from each of the coil groups of each phase to the outside of the motor case 31. These connection cables 36a are connected to a battery 10 mounted as a drive power source via an inverter 6. In the case of this automobile 1, a battery 10 with a rated voltage of 50 V or less, specifically a 48 V battery, is used.

[0048] The battery 10 supplies DC power to the inverter 6. The inverter 6 converts the DC power into three-phase AC and energizes the drive motor 3. Thereby, the rotor 33 is rotationally driven, and the power (rotational power) of the drive motor 3 is output to the automatic transmission 8 via the shaft 32.

[0049] In the case of this motor vehicle 1, the automatic transmission 8 is a multi-stage automatic transmission (so-called AT). As shown in FIG. 1, the automatic transmission 8 has an input shaft 80 at one end thereof, and the input shaft 80 is connected to the drive motor 3 (shaft 32). At the other end of the automatic transmission 8, there is an output shaft 81 that rotates independently of the input shaft 80.

[0050] Between these input shaft 80 and output shaft 81, a transmission mechanism composed of a torque converter 84, a plurality of planetary gear mechanisms 82, and a plurality of transmission clutches 83 (including brakes, corresponding to the "clutch" of the disclosed technology) is incorporated. Note that the transmission mechanism is shown in a simplified manner.

[0051] By switching these transmission mechanisms, it is configured to be able to switch between forward and reverse, and to change the rotational speed between the input shaft 80 and the output shaft 81 of the automatic transmission 8, that is, to switch the transmission ratio.

[0052] For example, the input side 83a of each transmission clutch 83 is configured to be connectable to the input shaft 80 via the torque converter 84. The output side 83b of each transmission clutch 83 is connected to the output shaft 81 via the corresponding planetary gear mechanism 82.

[0053] When a specific transmission clutch 83 is selected and that transmission clutch 83 is engaged, the input shaft 80 and the output shaft 81 of the automatic transmission 8 are connected via that transmission clutch 83 and the corresponding planetary gear mechanism 82. Thereby, the transmission ratio and the like are switched.

[0054] The output shaft 81 is connected to the differential gear 9 via a propeller shaft 11 that extends in the longitudinal direction of the vehicle body and is arranged coaxially with the output shaft 81. A pair of drive shafts 13, 13 that extend in the vehicle width direction and are connected to the left and right drive wheels 4R, 4R are connected to the differential gear 9.

[0055] The rotational power output through the propeller shaft 11 is distributed by the differential gear 9 and then transmitted to each drive wheel 4R through these pair of drive shafts 13, 13. Brakes 14 are attached to each of the wheels 4F, 4F, 4R, 4R to brake their rotation.

[0056] (Device of the control system) In the motor vehicle 1, in order to control its running according to the driver's operation, the above-described units of the ECU 20, MCU 21, TCU 22, BCU 23, and GCU 24 are installed. Each of these units is composed of hardware such as a processor, a memory, and an interface, and software such as a database and a control program. Each of these units is connected, for example, by a CAN (Controller Area Network) and is configured to be able to communicate electrically with each other.

[0057] The ECU 20 is a unit that mainly controls the operation of the engine 2. The MCU 21 is a unit that mainly controls the operation of the drive motor 3. The TCU 22 is a unit that mainly controls the operation of the automatic transmission 8. The BCU 23 is a unit that mainly controls the operation of the brake 14. The GCU 24 is a higher-level unit that is electrically connected to these ECU 20, MCU 21, TCU 22, BCU 23 and comprehensively controls them.

[0058] The "control device" in the disclosed technology is composed of these units. In particular, the MCU 21 that mainly controls the operation of the drive motor 3 and the TCU 22 that mainly controls the operation of the automatic transmission 8 constitute the main body of the control device.

[0059] The engine rotation sensor 50 is attached to the engine 2, detects the rotational speed of the engine 2, and outputs it to the ECU 20. The motor rotation sensor 51 is attached to the drive motor 3, detects the rotational speed and rotational position of the drive motor 3, and outputs them to the MCU 21. The current sensor 52 is attached to the connection cable 36a, detects the current value applied to each coil 36, and outputs it to the MCU 21.

[0060] The magnetic force sensor 53 is attached to the drive motor 3, detects the magnetic force of the magnetically variable magnet 35, and outputs it to the MCU 21. The accelerator sensor 54 is attached to the accelerator pedal (accelerator pedal 15) that the driver depresses when driving the vehicle 1, detects the accelerator opening corresponding to the output required for driving the vehicle 1, and outputs it to the ECU 20. The transmission sensor 55 detects the rotational speed and engagement torque of each transmission clutch 83, the rotational speed of the output shaft 81, etc., and outputs them to the TCU 22.

[0061] Based on the signals of the detection values input from these sensors, each unit cooperates to control each device in the drive system, and thus the vehicle 1 travels. For example, when the vehicle 1 travels with the driving force of the engine 2, the ECU 20 controls the operation of the engine 2 based on the detection values of the accelerator sensor 54 and the engine rotation sensor 50.

[0062] Then, the TCU 22 controls the relay clutch 5 to be in the engaged state and switches the transmission mechanism of the automatic transmission 8 according to the driving state of the vehicle 1. When the vehicle 1 is braking, the BCU 23 controls each brake 14. During braking by regeneration, the TCU 22 controls the relay clutch 5 to be in the non-engaged state or the partially engaged state, and engages a predetermined transmission clutch 83 of the automatic transmission 8. Then, the MCU 21 generates electricity with the drive motor 3 and controls the electric power to be recovered by the battery 10.

[0063] Figure 3 shows the TCU 22 and the main input / output devices related thereto. In the TCU 22, a relay clutch control unit 22a and a transmission clutch control unit 22b are provided by its hardware and software as functional configurations. The relay clutch control unit 22a controls the operation of the relay clutch 5. The transmission clutch control unit 22b controls the operation of each of the transmission clutches 83.

[0064] <Control of the drive motor> The MCU 21 controls the vehicle 1 to travel using the power output by the drive motor 3 in a state where the drive motor 3 outputs alone or in a state where the output of the engine 2 is assisted as necessary.

[0065] Specifically, based on the detection values of the accelerator sensor 54, the engine rotation sensor 50, etc., the ECU 20 sets the torque output by the engine 2. Accordingly, the GCU 24 sets the required torque amount (required torque) for the drive motor 3 within a predetermined output range according to the preset output distribution ratio between the engine 2 and the drive motor 3. The MCU 21 controls the drive motor 3 so that the required torque is output.

[0066] Figure 4 shows the MCU 21 and the main input / output devices related thereto. In the MCU 21, a motor output control unit 21a and a magnetization control unit 21b are provided by its hardware and software as functional configurations.

[0067] The motor output control unit 21a has a function of controlling the drive of the drive motor 3, and outputs the required power to the drive motor 3 by controlling the drive current flowing through the coil 36. On the other hand, the magnetization control unit 21b changes the magnetic force of the magneto - rheological magnet 35 by controlling the magnetization current flowing through the coil 36.

[0068] Specifically, data such as maps and tables that define the output range of the drive motor are preset in the MCU 21. The motor output control unit 21a controls the drive motor 3 within that output range by referring to the data.

[0069] Furthermore, the output range of the drive motor 3 is partitioned into a plurality of magnetization regions. And, in accordance with each of these magnetization regions, the magnetization control unit 21b is configured to change the magnetic force of the magnetically variable magnet 35. That is, when the magnetization region transitions to another adjacent magnetization region, the magnetization control unit 21b changes the magnetic force of the magnetically variable magnet 35 to the magnetic force optimum value corresponding to that magnetization region.

[0070] (Specific Example of Drive Motor Control) FIG. 5 shows a simplified system diagram regarding the control of the drive motor 3. FIG. 6 shows an example of the control of the drive motor 3 performed by the MCU 21. While referring to these, the specific control flow of the drive motor 3 will be described. Note that the drive motor 3 is controlled by vector control using the torque current command Iq * and the excitation current command Id * .

[0071] When the vehicle 1 becomes drivable, the MCU 21 constantly receives detection values from the current sensor 52, the motor rotation sensor 51, and the magnetic force sensor 53 (step S1). Similarly, the ECU 20 also constantly receives detection values from the accelerator sensor 54 and the engine rotation sensor 50.

[0072] The GCU 24 acquires the detection value of the accelerator sensor 54 from the ECU 20, and sets the torque required for the drive motor 3 (required torque) among the torque output to the drive wheels 4R according to a preset output distribution ratio between the engine 2 and the drive motor 3. The GCU 24 outputs a command (torque command value T * ) for outputting the required torque to the MCU 21.

[0073] That is, in the MCU 21, the output of the drive motor 3 is controlled based on a predetermined target torque (so-called torque control). By the torque control, the torque (motor torque) output by the drive motor 3 is controlled to match the target torque. Therefore, when the above-described command is input while the vehicle 1 is running, the MCU 21 controls the drive motor 3 with the required torque as the target torque. By the torque control of the drive motor 3, the vehicle 1 runs according to the driver's request.

[0074] During the operation of this vehicle 1, when shifting the magnetization region as described above, the torque control is interrupted, and control for applying a high voltage to the coil 36 of the drive motor 3 is executed (magnetic force change control). By the magnetic force change control, the magnetic force of the magneto-magnetically variable magnet 35 is changed.

[0075] Specifically, when the MCU 21 (motor output control unit 21a) receives an input of the torque command value T * (Yes in step S2), it executes arithmetic processing of a command (drive current command value Iq * ) for outputting a drive current (torque current component) that generates that torque (step S3). Also, the MCU 21 (magnetization control unit 21b) executes arithmetic processing of a command (magnetization state command value Φ * ) for outputting an optimum magnetic force value corresponding to an appropriate magnetization region (step S4). The magnetization control unit 21b executes arithmetic processing of a command (magnetic force current command value Id * ) for outputting a torque current component corresponding to the magnetic force of the magneto-magnetically variable magnet 35 based on the magnetization state command value Φ * (step S5).

[0076] The MCU 21 determines whether it is necessary to change the magnetic force of the magneto-magnetically variable magnet 35 based on the calculated drive current command value Iq * and the magnetic force current command value Id * (step S6). For example, as described above, when it is required to output the required torque and shift the magnetization region, it is determined that it is necessary to change the magnetic force of the magneto-magnetically variable magnet 35, and when it is required to output the required torque and the vehicle is located in the same magnetization region, it is determined that it is not necessary to change the magnetic force of the magneto-magnetically variable magnet 35.

[0077] Then, when the MCU 21 determines that it is not necessary to change the magnetic force of the magnetically variable magnet 35, it determines whether the torque to be output is greater than the torque T1 at which the drive motor 3 runs idle (step S7). And when the torque to be output is greater than the torque T1, the MCU 21 controls the drive motor 3 by normal vector control.

[0078] That is, the motor output control unit 21a performs arithmetic processing of a command (voltage command value Vuvw * ) output for performing PWM control based on the detection values of the current sensor 52 and the motor rotation sensor 51 by current control (step S8). Then, a switching command value is calculated by PWM control (step S9).

[0079] By outputting the switching command value to the inverter 6 through the driver circuit, a plurality of switching elements are turned on and off inside the inverter 6. Thereby, a predetermined three-phase alternating current (drive current) is supplied to each coil group, and the drive motor 3 rotates at the required torque (step S10).

[0080] On the other hand, when the MCU 21 determines that it is necessary to change the magnetic force of the magnetically variable magnet 35 (No in step S6), the magnetization control unit 21b executes magnetic force change control (step S11).

[0081] Also, even when the MCU 21 determines that it is not necessary to change the magnetic force of the magnetically variable magnet 35, if it determines that the torque to be output is equal to or less than the torque T1 at which the drive motor 3 runs idle (No in step S7), the magnetization control unit 21b executes magnetic force change control (step S11).

[0082] That is, when the required amount of rotational power of the drive motor 3 becomes almost zero (zero), the magnetic force variable magnet 35 has its magnetic force changed to the initial state (reset). In the case of the automobile 1, for example, there may be a case where the accelerator pedal 15 is suddenly depressed and rapidly accelerated from an idling state or a stopped state.

[0083] In the case of the magnetic force variable magnet 35, since the magnetic force in the initial state is set high according to high load, by resetting the magnetic force during idling operation, even when such rapid acceleration occurs, the drive motor 3 can be appropriately driven.

[0084] Fig. 7 shows the main processing flow of the magnetic force change control. When the magnetization control unit 21b is requested for magnetic force change control, it determines the direction of the magnetization process based on the magnetization state command value Φ * That is, it determines whether to execute a process of increasing the magnetic force of the magnetic force variable magnet 35 (magnetic flux increasing process) or a process of decreasing the magnetic force of the magnetic force variable magnet 35 (magnetic flux decreasing process). The magnetization control unit 21b further specifies the change amount of the increasing or decreasing magnetic force.

[0085] Then, based on the detected value of the motor rotation sensor 51, the magnetization control unit 21b determines whether the position of the rotor 33 with respect to the stator 34 (position in the rotation direction) is at a position suitable for the magnetization process (step S21). When the rotor 33 is at an appropriate position, it outputs a magnetization current (step S22). The magnetization current is a pulsed current that generates an electromagnetic force greater than the coercive force of the magnetic force variable magnet 35. In the magnetic flux increasing process and the magnetic flux decreasing process, the direction of the magnetic force lines of the electromagnetic force is reversed.

[0086] The magnetization control unit 21b determines whether the magnetic force of the magnetic force variable magnet 35 is approximately the same as the magnetic force optimum value indicated by the magnetization state command value Φ * (step S23), and executes the magnetization process until the magnetic force of the magnetic force variable magnet 35 becomes approximately the same as the magnetic force optimum value. When resetting the magnetic force of the magnetic force variable magnet 35, the magnetization process is executed until it becomes approximately the same as the initial magnetic force.

[0087] Then, when the magnetic force of the magnet 35 with variable magnetic force becomes substantially the same as its optimal magnetic force value or the initial magnetic force, the magnetic force change control is terminated, and as shown in FIG. 6, the drive motor 3 is controlled by normal vector control (steps S8 to S10).

[0088] <Control of Transmission Clutch> As described above, in this motor vehicle 1, the magnetic force change control is also executed during the operation of the motor vehicle 1. When the magnetic force change control is executed during the operation of the motor vehicle 1, there is a concern that a torque shock may occur in the traveling motor vehicle 1, giving the driver a sense of discomfort.

[0089] The upper diagram of FIG. 8 illustrates the change over time of the motor torque Tm during the magnetic force change control. In this illustration, the magnetization process (an example of the magnetic force change control) is being executed during the period from time t1 to t1'. And the period from t1' to t2 is the period in which the motor torque Tm is made to match the required torque Ta.

[0090] That is, while confirming the change in the magnetic force, control (learning control) is executed to make the drive current value (the value of the q-axis current) learned to correspond to the magnetic force after magnetization. The learning control is control associated with the change in the magnetic force and is included in the magnetic force change control. Since the drive motor 3 is torque-controlled during the running of the motor vehicle 1, the motor torque Tm before and after the execution of the magnetic force change control matches the required torque Ta.

[0091] Tt is the clutch engagement torque in the automatic transmission 8. The clutch engagement torque Tt is the engagement torque of the transmission clutch 83 that connects the input shaft 80 and the output shaft 81 of the automatic transmission 8. The clutch engagement torque Tt is adjusted by well-known hydraulic control. Specifically, if the hydraulic pressure supplied to the automatic transmission 8 is lowered, the clutch engagement torque Tt becomes smaller, and if the hydraulic pressure supplied to the automatic transmission 8 is increased, the clutch engagement torque Tt becomes larger.

[0092] In order to ensure that the motor torque Tm is transmitted to the drive wheels 4R, usually, the clutch engagement torque Tt is controlled (clutch full engagement control) to be a value sufficiently higher than the transmission torque and the required torque Ta. The hydraulic pressure supplied to the automatic transmission 8 during clutch full engagement control is, for example, 1000 kPa and at least 500 kPa or more.

[0093] That is, under clutch full engagement control, the transmission clutch 83 is fully engaged, the rotational speeds are the same on both the input side 83a and the output side 83b of the transmission clutch 83, and the torque on the input side 83a (input torque) input to the transmission clutch 83 and the torque on the output side 83b (output torque) output from the transmission clutch 83 are also in a state of matching the required torque Ta.

[0094] During magnetic force change control, in order to generate a large electromagnetic force, a magnetization current (d-axis current) is passed through the coil 36. As a result, a high voltage far exceeding the drive voltage is applied to the drive motor 3. Therefore, as shown in the upper figure of Fig. 8, during magnetic force change control, a peak-shaped high motor torque Tm far exceeding the required torque Ta is output from the drive motor 3. As a result, under clutch full engagement control, a torque shock occurs in the traveling automobile 1, raising concerns about giving the driver a sense of discomfort.

[0095] On the other hand, if the transmission clutch 83 is slipped when performing magnetic force change control, such a torque shock can be suppressed. That is, as shown in the upper figure of Fig. 8, the hydraulic pressure supplied to the automatic transmission 8 is lowered during the period before and after magnetic force change control. By doing so, the clutch engagement torque Tt is reduced, and the clutch engagement torque Tt is controlled to substantially match the required torque Ta.

[0096] Specifically, as shown in the upper diagram of FIG. 8, immediately before the start of the magnetic force change control (time t1) (time t0), instead of the clutch full engagement control, control is executed to reduce the clutch engagement torque Tt until the transmission clutch 83 slips. As a result, even if a high motor torque Tm is output from the drive motor 3 by the magnetic force change control, torque exceeding the required torque Ta can be prevented from being transmitted to the drive wheels 4R. As a result, torque shock caused by the magnetic force change can be suppressed.

[0097] (Rotation surge) However, when the transmission clutch 83 is slipped, a phenomenon occurs in which the rotation of the drive motor 3 suddenly increases (so-called "surge").

[0098] The lower diagram of FIG. 8 shows the relationship between the motor torque Tm and the motor speed during the magnetic force change control. Here, the output of the engine 2 is not considered. Therefore, the motor speed is also the speed of the input shaft 80 of the automatic transmission 8. Also, the motor torque Tm corresponds to the torque (input torque) input to the automatic transmission 8. Since the clutch engagement torque Tt is controlled to match the required torque Ta, it corresponds to the torque (output torque) output from the automatic transmission 8.

[0099] Before the execution of the magnetic force change control, the drive motor 3 is rotating at a predetermined speed Ra. And at this time, since the transmission clutch 83 being used is fully engaged, both the input side 83a and the output side 83b of the transmission clutch 83 are also rotating at the speed Ra. Note that the output shaft 81 of the automatic transmission 8 is rotating at a speed changed by the planetary gear mechanism 82 corresponding to the transmission clutch 83.

[0100] When the transmission clutch 83 is effectively slipped during magnetic force change control, the drive motor 3 will rotate idly, so the motor speed will suddenly increase from the speed Ra corresponding to the required torque Ta. During learning control, it will increase further, and the motor speed will reach a state of being stuck at a high level. If this soaring phenomenon is not eliminated promptly, the transmission clutch 83 may be damaged due to frictional heat caused by slip.

[0101] (Micro slip control) As described above, in order to suppress the torque shock caused by magnetic force change control, it is necessary to slip the transmission clutch 83. To do this, it is necessary to significantly reduce the hydraulic pressure supplied to the automatic transmission 8 from the hydraulic pressure during clutch full engagement control and lower the clutch engagement torque.

[0102] Fig. 9 exemplifies the torque characteristics (transmission torque characteristics) transmitted in a state where the clutch engagement torque is lowered to near the transmission torque. The vertical axis is the output torque (Tout), and the horizontal axis is the input torque (Tin). Graph G1 represents the torque transmitted from the input side to the output side of the transmission clutch 83 when the hydraulic pressure is adjusted to 200 kPa and the transmission clutch 83 outputs a corresponding clutch engagement torque. Similarly, graph G2 represents the case when the hydraulic pressure is 210 kPa, and graph G3 represents the case when the hydraulic pressure is 190 kPa.

[0103] Like graphs G1 - G3, the transmission torque characteristics vary according to the hydraulic pressure, but for the same clutch, they have the same form of transmission torque characteristics even if the hydraulic pressures are different. That is, it has a region corresponding to a low input torque (low transmission torque region RL), a region corresponding to a high input torque (high transmission torque region RH), and a region existing between these low and high transmission torque regions (transition transmission torque region RM).

[0104] For example, when looking at graph G1, in the low transmission torque region RL (the region where the input torque is 35 Nm or less), the input torque and the output torque have the same value. That is, the transmission clutch 83 is in a engaged state, and all of the input torque is transmitted and output. In the transition transmission torque region RM (the region where the input torque is from 35 Nm to 50 Nm), the output torque is smaller than the input torque. That is, the transmission clutch 83 is in a slipping state, and a part excluding a portion of the input torque is transmitted and output.

[0105] In the high transmission torque region RH (the region where the input torque is 50 Nm or more), the output torque asymptotes to 45 Nm with respect to an increase in the input torque. That is, even if the input torque becomes higher hereafter, only the slip increases, and the increase in the input torque is not transmitted. The output torque becomes substantially constant at that value (corresponding to the upper limit transmission torque).

[0106] In other words, in the case of the transmission clutch 83 having this transmission torque characteristic, by adjusting the hydraulic pressure to 200 kPa, even if the input torque increases, the output torque can be limited to 45 Nm or less. Therefore, in the case of this transmission clutch 83, when the output torque (required torque Ta) at the time when magnetic force change control is required is 45 Nm, it is preferable to lower the hydraulic pressure supplied to the automatic transmission 8 and adjust it to 200 kPa.

[0107] Thus, for example, the hydraulic pressure is controlled so that the clutch engagement torque Tt (corresponding to the upper limit transmission torque) coincides with 45 Nm, and the input torque (output torque of the drive motor) is set to 50 Nm in consideration of the slip loss. By doing so, even if a peak torque (for example, 15 Nm, shown as Tp1 in FIG. 9) is generated in the input torque by the magnetic force change control, the output torque can be limited to 45 Nm, which is the required torque Ta. Therefore, the shock torque (shown as Ts1 in FIG. 9) generated in the output torque due to the influence of the peak torque Tp1 is almost nonexistent, and torque shock can be suppressed.

[0108] However, even in such a case, there is an excess torque difference (50 Nm - 45 Nm = 5 Nm) between the input torque and the output torque. Therefore, slip occurs due to that torque difference. However, if the difference in rotational speed between the input side and the output side of the clutch (clutch differential rotational speed) at that time is equal to or less than a predetermined value (for example, 100 rpm or less), both torque shock and slip loss can be minimized.

[0109] For example, if the input torque is 43 Nm and the output torque is 42 Nm, the clutch differential rotational speed is less than 100 rpm (about 20 rpm in this example), and the shock torque (Ts2) due to the influence of the peak torque Tp2 at that time can also be made small (3 Nm in this example). That is, both torque shock and slip loss can be minimized, and it becomes possible to achieve both suppression of torque shock and suppression of slip loss.

[0110] Specifically, the TCU 22 (transmission clutch control unit 22b) slips the transmission clutch 83 by lowering the clutch engagement torque to near the transmission torque immediately before the magnetic force change control. After that, control for slightly slipping the transmission clutch 83 (micro slip control) may be executed.

[0111] For example, if the output torque is 42 Nm in the above-described example, the hydraulic pressure of the automatic transmission 8 is lowered and adjusted to 200 kPa. Thereby, the transmission torque characteristics of the transmission clutch 83 become the state shown in the graph G1. Then, if the motor torque is controlled so that the input torque becomes 43 Nm, the transmission clutch 83 can be slipped at a clutch differential rotational speed of about 20 rpm.

[0112] Then, feedback control based on the clutch differential rotational speed (rotational speed feedback control) is executed. Thereby, immediately before the magnetic force change control, the transmission clutch 83 is stabilized in the slightly slipped state (micro slip state) at the above-described appropriate rotational speed, and the micro slip state is maintained.

[0113] If the transmission clutch 83 starts the magnetic force change control in a micro-slip state in this way, not only the torque shock associated with the magnetic force change control but also the slip loss associated with its suppression can be minimized. It is possible to achieve both the suppression of torque shock and the suppression of slip loss.

[0114] <Expansion of the execution range of the magnetic force change control> The magnetic force change control was assumed to be executed while avoiding the timing at which the automatic transmission 8 shifts gears from the viewpoint of suppressing the influence of disturbances. And in that case, the automatic transmission 8 was used for unintended purposes in order to execute the micro-slip control.

[0115] However, as the optimization of the motor efficiency progresses, it has been found that depending on the conditions, the frequency of the magnetic force change control may significantly exceed the assumption. For example, during driving in the WLTC mode, the frequency of the magnetic force change control can be several times that of shifting gears.

[0116] Therefore, from the viewpoint of suppressing fuel consumption (electricity cost), it is assumed that there may be cases where the magnetic force change control must be executed not only outside the shifting period of the automatic transmission 8 but also during the shifting period. For this purpose, it is preferable to expand the execution range of the magnetic force change control so that the magnetic force change control can be executed even during the shifting period. And if the magnetic force change control can be executed even during the shifting period, the magnetic force change control can be performed without considering shifting, so the motor efficiency will be further increased.

[0117] However, even in that case, it is preferable to suppress torque shock and reduce slip loss. In this regard, the inventors have found that during the shifting period, the transmission clutch 83 is in a slipping state, and if this is utilized well, it is possible to reduce slip loss and the like.

[0118] Fig. 10 shows a flowchart that forms the basis of magnetic force change control when the disclosed technology is applied. The control device (MCU21) determines whether magnetic force change control is to be executed during the driving of the vehicle 1 (step S31). Then, if it is determined that magnetic force change control is to be executed, it determines whether the magnetic force change control is to be executed during the gear shift period, that is, during the gear shift of the automatic transmission 8 (step S32).

[0119] As a result, if the execution of the magnetic force change control does not fall within the gear shift period, that is, if it is outside the gear shift period (No in step S32), as described above, the magnetic force change control for using the automatic transmission 8 for an unintended purpose (magnetic force change control during non-gear shift) is executed (step S33). On the other hand, if the magnetic force change control falls within the gear shift period (Yes in step S32), the magnetic force change control corresponding to the state change during the gear shift of the automatic transmission 8 (magnetic force change control during gear shift) is executed (step S34).

[0120] Note that depending on the situation, even if the magnetic force change control can be executed outside the gear shift time, it may be possible to wait for the timing when the automatic transmission 8 shifts gears and execute the magnetic force change control within the gear shift period.

[0121] (Specific example of magnetic force change control during non-gear shift) Fig. 11 shows a specific example (time chart) of the magnetic force change control (magnetic force change control during non-gear shift) executed outside the gear shift period of the automatic transmission 8. Fig. 12 shows a flowchart representing the main processing flow performed by the control device corresponding to the time chart. Here, the power is only from the drive motor 3. This specific example corresponds to the illustration of the above-described micro slip control.

[0122] In Fig. 11, the upper part is a time chart regarding the hydraulic pressure of the automatic transmission 8. Pc represents the hydraulic pressure during clutch full engagement control, and Ps represents the target hydraulic pressure, respectively.

[0123] The middle section is a time chart regarding the torque of the transmission clutch 83. The dashed line L1 represents the input torque, the dashed-dotted line L2 represents the output torque, the solid line L3 represents the clutch engagement torque, and the chain-dotted line L4 represents the upper limit transmission torque, respectively.

[0124] The lower section is a time chart regarding the clutch differential rotational speed. It represents the difference between the rotational speed of the input side 83a and the rotational speed of the output side 83b of the transmission clutch 83.

[0125] As shown in FIG. 12, when the control device (MCU21) determines that magnetic force change control is to be executed outside the shift period of the automatic transmission 8, the TCU22 sets the target hydraulic pressure Ps of the automatic transmission 8 according to the required torque Ta at that time (step S41). As in the previous example, when the required torque Ta (the input torque and the output torque are the same) at that time is 43 Nm, the target hydraulic pressure Ps may be set to 200 kPa.

[0126] At this time, since the clutch full engagement control is being executed for the transmission clutch 83, the hydraulic pressure Pc is high (for example, 1000 kPa), and the clutch engagement torque is overwhelmingly higher than the transmission torque. The TCU22 reduces the pressure to the set target hydraulic pressure Ps in order to start the micro-slip control. Accordingly, the clutch engagement torque decreases to near the transmission torque (steps S42, t0 to t1). Thereby, the transmission clutch 83 starts to slip, and the clutch differential rotational speed increases.

[0127] Then, the MCU21 starts the previous-stage feedback control so as to converge to a predetermined micro-slip state (step S43). Specifically, based on the detected value of the transmission sensor 55, the rotational speed of the input side, that is, the rotational speed output by the drive motor 3, is adjusted so that the clutch differential rotational speed actually measured or estimated becomes equal to or less than the target differential rotational speed Rs (step S44). That is, the previous-stage feedback control corresponds to the "rotational speed feedback control" in the disclosed technology.

[0128] Regarding the rotational speed of the drive motor 3, it can be controlled with relatively high precision. Also, the clutch differential rotational speed can quickly converge to the target differential rotational speed Rs (for example, 20 rpm). When the clutch differential rotational speed converges to the target differential rotational speed Rs, according to the transmission torque characteristics, the input torque stabilizes at 43 Nm and the output torque stabilizes at 42 Nm (t1 to t2).

[0129] In such a state, the MCU 21 starts magnetic force change control (step S45). When executing the magnetic force change control, as described above, a high motor torque is instantaneously output from the drive motor 3, and the torque is superimposed on the input torque (t2 to t3).

[0130] Accordingly, the motor rotational speed (input torque) increases, but since it is regulated by the upper limit transmission torque (45 Nm), the output torque only rises up to 45 Nm. The shock torque at that time is 3 Nm as indicated by the arrow Y1 in FIG. 11, and the driver cannot perceive it. Therefore, torque shock can be effectively suppressed.

[0131] Even immediately after the magnetic force change control, torque fluctuations occur as indicated by the arrow Y2 in FIG. 11. It has been found that this torque fluctuation (post - torque shock) can occur within a predetermined variation range (for example, ±7 Nm) with respect to the actual torque (the torque output to the driving wheels, which is the same as the required torque or output torque here, 43 Nm).

[0132] This post - torque shock converges by the above - mentioned learning control, but it takes several milliseconds to several tens of milliseconds to converge. Therefore, although it is instantaneous, there is a concern that it may give the driver a sense of discomfort.

[0133] When the post - torque shock occurs on the plus side, it can be regulated by the upper limit transmission torque. On the other hand, when the post - torque shock occurs on the minus side as in the illustrated example, it is output as a shock (pull - in shock) to pull it in. Therefore, from the perspective of torque shock suppression, it is preferable that the post - torque shock occurs on the plus side with respect to the actual torque.

[0134] Therefore, in this embodiment, the command value of torque control during non-shifting magnetic force change control (which is the same as the required torque here) has a predetermined amount considering the variation range offset to the positive side (for example, +15 Nm). By doing so, the post-torque shock always occurs on the positive side, so the post-torque shock can also be effectively suppressed.

[0135] Although the clutch differential rotation speed also shows a slight increase, it can be suppressed to 100 rpm or less, which is the allowable level. Therefore, the slip loss can also be effectively suppressed.

[0136] The MCU 21 determines whether the magnetic force change control has ended (step S46). When the magnetic force change control has ended, the MCU 21 starts power control targeting the micro-slip state (step S47).

[0137] In power control, torque control is executed (t3 to t4) so that the power output from the drive wheel 4R, that is, the multiplication value of the torque T and the rotation speed R of the drive wheel 4R, becomes a predetermined target power value (target power value). That is, in power control, torque control is executed with the motor torque Tm corresponding to the target power value as the target torque instead of the required torque Ta.

[0138] If the target power value is constant, when the motor rotation speed Rm is high, the target torque decreases accordingly, and when the motor rotation speed Rm is low, the target torque increases accordingly. Therefore, according to power control, unlike torque control, both the rotation speed and the torque can be adjusted in a well-balanced manner. Thereby, the transmission clutch 83 whose rotation speed and torque have become unstable due to the magnetic force change control quickly converges to the micro-slip state.

[0139] After the predetermined period has elapsed and the clutch differential rotational speed reaches a predetermined differential rotational speed Rf greater than the target differential rotational speed Rs (Yes in step S48), the MCU 21 starts the subsequent feedback control (step S49). Specifically, the rotational speed on the input side, that is, the rotational speed output by the drive motor 3, is adjusted so that the clutch differential rotational speed converges to the target differential rotational speed Rs (step S50). Thereby, the clutch differential rotational speed can converge to the target differential rotational speed Rs more quickly and can be maintained in a micro-slip state (t4 to t5).

[0140] Thereafter, the TCU 22 boosts the hydraulic pressure of the automatic transmission 8 to the normal hydraulic pressure and returns to the state of clutch full engagement control (step S51, t6). Then, the MCU 21 resumes the normal torque control (step S52).

[0141] Note that the power control after the end of the magnetic force change control may be omitted, and immediately after setting the target differential rotational speed Rs to 0 (zero), the process may shift to the subsequent feedback control. By doing so, as indicated by the virtual line Ln in FIG. 11, the clutch differential rotational speed can be eliminated in an extremely short time, and the slip loss can be further suppressed.

[0142] (State changes during gear shifting of the automatic transmission) Prior to the description of a specific example of the magnetic force change control (gear shift magnetic force change control) executed during the gear shift period of the automatic transmission 8, the state changes of the automatic transmission 8 during gear shifting, which are the premise thereof, will be described.

[0143] FIG. 13 illustrates a time chart of the main specifications (vehicle speed, vehicle acceleration, input torque, engine speed, engagement torque) during gear shifting of the automatic transmission 8. Here, the automobile 1 is traveling only by the drive of the engine 2 (the drive motor 3 is not driving). The vehicle speed is gradually increasing without being accelerated. Under such circumstances, the automatic transmission 8 is upshifted. Due to the gear shift, the rotational speed of the engine 2 is switched from the first gear to the second gear.

[0144] In the automatic transmission 8, a shift is made from the first clutch (transmission clutch 83 corresponding to the first gear before shifting) to the second clutch (transmission clutch 83 corresponding to the second gear after shifting). That is, the engaged state and the released state are switched between the first clutch and the second clutch.

[0145] The shifting period of the automatic transmission 8 is generally composed of a period consisting of a pre-charge & hold phase, a torque phase, and an inertia phase from the content of the state change.

[0146] The pre-charge & hold phase corresponds to the preparation stage for shifting. During the period of the pre-charge & hold phase, mainly to smoothly and promptly perform the engagement operation of the second clutch, the clutch engagement torque of the second clutch is preliminarily increased to near its transmission torque (pre-charge), and that state is maintained. Since no hydraulic pressure is supplied to the second clutch before shifting, the pre-charge & hold phase suppresses the response delay of the hydraulic pressure.

[0147] The period of the pre-charge & hold phase also smoothly and promptly performs the release operation of the first clutch. For this purpose, the clutch engagement torque of the first clutch is preliminarily decreased to near its transmission torque and maintained in that state. During the period of the pre-charge & hold phase, the output torque is maintained by the first clutch, and the friction elements of the second clutch are set in a state of slipping without load (zero-touch state) substantially without transmitting torque.

[0148] During the torque phase, the transmission of torque is switched from the first clutch to the second clutch. Specifically, in the first clutch, the hydraulic pressure is gradually decreased from the standby state near the transmission torque, so as to shift from the engaged state to the released state. In the second clutch, the hydraulic pressure is gradually increased from the standby state near the transmission torque, so as to shift from the released state to the engaged state.

[0149] During the torque phase, both the first clutch and the second clutch are in a slipping state while holding the input torque generated by the driving of engine 2 by torque control. The first clutch slips while decreasing its rotational speed, and the second clutch slips while increasing its rotational speed.

[0150] During this period, for the second clutch, hydraulic feedback control based on the clutch differential rotational speed is executed. Thereby, the hydraulic pressure of the second clutch gradually increases according to the decrease in the hydraulic pressure of the first clutch.

[0151] Therefore, with the magnitude of the transmitted torque held constant, the transmission of torque from the first clutch to the second clutch is smoothly switched. Then, when the first clutch becomes open and the transmission of torque is completely switched from the first clutch to the second clutch, the process shifts from the torque phase to the inertia phase.

[0152] The rotational speed (input - side rotational speed) immediately after shifting from the torque phase to the inertia phase is the rotational speed corresponding to the gear ratio of the first clutch. During the inertia phase, the switching is performed from that rotational speed to the rotational speed corresponding to the gear ratio of the second clutch. Note that the rotational speed on the output side during the shifting period hardly changes due to inertia.

[0153] During the inertia phase, the first clutch is not slipping, while the second clutch continues to slip from the torque phase. Since it is an upshift, the gear ratio of the second clutch is smaller than that of the first clutch. And the input torque generated by the driving of engine 2 is maintained by torque control. Therefore, the rotational speed of engine 2 gradually decreases.

[0154] At this time, in the second clutch, slipping occurs due to the sliding of the relatively low - rotational - speed input - side friction element with respect to the relatively high - rotational - speed output - side friction element. Thereby, the input torque of the drive motor 3 decreases. That is, it is in a state similar to the occurrence of a draw - in shock.

[0155] The slip of the second clutch gradually decreases. Then, when the slip disappears and the rotation becomes synchronized between the input side and the output side of the second clutch, and the second clutch reaches the rotational speed corresponding to its gear ratio, the inertia phase ends.

[0156] After the end of the inertia phase, by supplying hydraulic pressure to the automatic transmission 8, clutch full engagement control for the second clutch is performed, and the gear shift of the automatic transmission 8 is completed.

[0157] (Specific Example of Magnetic Force Change Control during Gear Shift) As described above, during the gear shift of the automatic transmission 8, there is a period when the transmission clutch 83 slips. The inventors have found that by making good use of this, not only can magnetic force change control be simply performed, but also slip loss can be effectively reduced.

[0158] That is, during the gear shift period of the automatic transmission 8, the transmission clutch 83 slips during the precharge & hold phase, torque phase, and inertia phase. Among them, magnetic force change control is executed during the inertia phase.

[0159] The period of the precharge & hold phase is a preparation period for gear shift aimed at suppressing the response delay of hydraulic pressure. Therefore, the period of the precharge & hold phase is not suitable for executing magnetic force change control, and there is no such time margin either.

[0160] Also, during the torque phase, both the first clutch and the second clutch are slipping, and torque transmission is switched while holding the input torque by torque control. Therefore, from the perspective of control stability, it is not preferable to repeatedly execute magnetic force change control.

[0161] On the other hand, during the inertia phase, as described above, the switching from the first clutch to the second clutch is substantially completed, and the second clutch is slipping with the engagement torque reduced to near the transmission torque.

[0162] That is, the inertia phase period is in the same state as the period before the micro-slip control. Therefore, if rotational speed feedback control is executed using the slipping second clutch, the micro-slip control can be easily executed. Since the slip associated with the gearshift is utilized, the slip loss associated with the micro-slip control can also be reduced.

[0163] During the inertia phase period, in particular, it is preferable to start the magnetic force change control at the initial stage of the inertia phase. Here, the initial stage means the period immediately after the start of the inertia phase and the period in the vicinity thereof, and at least the period before the middle thereof.

[0164] By doing so, the torque generated along with the magnetic force change control is added to the second clutch that is slipping in the torque phase, thereby increasing the slip. As a result, the synchronization of the rotational speed is promoted. It becomes possible to shorten the inertia phase period and the gearshift period. If the inertia phase period is shortened, the slip loss is further reduced.

[0165] For example, when the gearshift of the automatic transmission 8 is a downshift, it is preferable to offset the command value of the torque control so that the torque fluctuation associated with the magnetic force change control during the gearshift occurs on the plus side with respect to the actual torque.

[0166] When the gearshift is a downshift, the gear ratio is larger for the second clutch than for the first clutch. Therefore, the rotational speed of the engine 2 gradually increases. At this time, in the second clutch during the inertia phase period, the relatively high-rotation input-side friction element slides relative to the relatively low-rotation output-side friction element, thereby slipping. As a result, contrary to the state shown in FIG. 13, the input torque of the drive motor 3 increases. That is, it is in a state similar to when a torque shock occurs.

[0167] Therefore, similar to suppressing the post-torque shock during non-shifting magnetic force change control, it is preferable to offset the command value of torque control during shifting by a predetermined amount (e.g., +15 Nm) considering the variation range. By doing so, the torque shock will always occur on the positive side, eliminating the pull-in shock and effectively suppressing the torque shock as well. Moreover, since the inertia phase period can be shortened, the slip loss can also be effectively reduced.

[0168] On the other hand, when the shift is an upshift, it is preferable to offset the command value of torque control so that the torque fluctuation associated with the shifting magnetic force change control occurs on the negative side with respect to the actual torque.

[0169] That is, the period of the inertia phase during an upshift becomes the same state as when the pull-in shock occurs as described above. Therefore, contrary to suppressing the post-torque shock during non-shifting magnetic force change control, the command value of torque control during shifting is offset by a predetermined amount considering the variation range to the negative side (e.g., -15 Nm).

[0170] By doing so, the torque shock will always occur on the negative side, so the synchronization of the rotational speed of the second clutch can be promoted, and the inertia phase period can be further shortened. Thereby, the slip loss can be further effectively reduced.

[0171] FIG. 14 shows a specific example (time chart) of shifting magnetic force change control corresponding to the example shown in FIG. 13. FIG. 15 shows a flowchart representing the main processing flow performed by the control device corresponding to the time chart.

[0172] As shown in FIG. 15, the TCU 22 determines whether or not the torque phase has ended (step S61). When it is determined that the torque phase has ended, the MCU 21 starts the front-stage feedback control so that the second clutch converges to a predetermined minute slip state (step S62). Then, the rotational speed on the input side of the second clutch is adjusted so that the clutch differential rotational speed becomes equal to or less than the target differential rotational speed Rs (for example, 20 rpm) (step S63). That is, the front-stage feedback control corresponds to the "rotational speed feedback control" in the disclosed technology.

[0173] In such a state, the MCU 21 starts the magnetic force change control (step S64). As a result, during an upshift, as indicated by arrow A1 in FIG. 14, a torque shock occurs in a state where an additional load is applied to the negative side. Therefore, the slip of the second clutch increases, and the synchronization of the rotational speed of the second clutch is promoted.

[0174] The MCU 21 determines whether or not the magnetic force change control has ended (step S65). When the magnetic force change control has ended, the MCU 21 starts the power control targeting the minute slip state (step S66). As a result, the second clutch whose rotational speed and torque have become unstable due to the magnetic force change control quickly converges to the minute slip state.

[0175] When a predetermined period has elapsed and the clutch differential rotational speed reaches a predetermined differential rotational speed Rf greater than the target differential rotational speed Rs (Yes in step S67), the MCU 21 starts the rear-stage feedback control (step S68). Specifically, the rotational speed on the input side is adjusted so that the clutch differential rotational speed becomes 0 (zero), that is, the rotational speeds on the input side and the output side of the second clutch are synchronized (step S69).

[0176] As a result, as indicated by arrow A2 in FIG. 14, the period of the inertia phase (shift period) is shortened compared to that during normal shifting. Not only can the magnetic force change control be performed during shifting, but also the suppression of the shock associated with the magnetic force change control and the reduction of the slip loss can be effectively achieved.

[0177] After the end of the magnetic force change control, the power control may be omitted, and immediately after setting the target differential rotation speed Rs to 0 (zero), the subsequent feedback control may be shifted to. By doing so, the clutch differential rotation speed can be eliminated in an extremely short time, and the slip loss can be further suppressed.

[0178] Note that the disclosed technology is not limited to the above-described embodiments, and also includes various other configurations. For example, the configuration of the vehicle 1 is illustrative and can be changed according to the specifications.

Explanation of Reference Numerals

[0179] 1 Vehicle (electric vehicle) 2 Engine 3 Drive motor 4 Wheel 4R Driving wheel 5 Relay clutch 6 Inverter 8 Automatic transmission 20 Engine control unit (ECU) 21 Motor control unit (MCU) 21a Motor output control unit 21b Magnetization control unit 22 Transmission control unit (TCU) 22a Relay clutch control unit 22b Transmission clutch control unit 23 Brake control unit (BCU) 24 Integrated control unit (GCU) 31 Motor case 32 Shaft 33 Rotor 34 Stator 35 Magnet (magnetic force variable magnet) 36 Coil 80 Input shaft 81 Output shaft 82 Planetary gear mechanism 83 Transmission clutch (clutch) 83a Input side 83b Output side

Claims

1. A drive motor in which the magnetic poles of a rotor are constituted by a magnetic force variable magnet whose magnetic force can be changed, and an automatic transmission disposed between the drive motor and a drive wheel and including a plurality of clutches, and a control device for an electric vehicle capable of traveling using electric power, In the case of shift-time magnetic force change control for executing magnetic force change control for changing the magnetic force of the magnetic force variable magnet during a shift period of the automatic transmission, among the shift periods of the automatic transmission, after the period of a torque phase for switching torque transmission from a predetermined first clutch before shifting to a predetermined second clutch after shifting, and during a period of an inertia phase for switching to a rotation speed corresponding to a gear ratio from the first clutch to the second clutch, the control device for an electric vehicle that executes the magnetic force change control.

2. In the control device for an electric vehicle according to Claim 1, A control device for an electric vehicle that starts the magnetic force change control at the initial stage of the inertia phase.

3. In the control device for an electric vehicle according to Claim 1 or 2, During traveling of the electric vehicle, together with torque control for controlling the motor torque output by the drive motor so as to match a required torque required to be output to the drive wheel, clutch fully engaged control for making the engagement torque of the engaged clutch higher than the transmission torque is executed. In the case of non-shift-time magnetic force change control for executing the magnetic force change control outside the shift period of the automatic transmission, instead of the clutch fully engaged control, by lowering the engagement torque to the vicinity of the transmission torque, the clutch is slipped, and by executing rotation speed feedback control based on the differential rotation speed between the input side and the output side of the clutch, minute slip control for minutely slipping the clutch at a predetermined rotation speed immediately before the magnetic force change control is executed. In the case of the shift-time magnetic force change control, by executing the rotation speed feedback control using the second clutch that is slipping during the period of the inertia phase, the control device for an electric vehicle that executes the minute slip control.

4. In the control device for an electric vehicle according to Claim 3, When the shift of the automatic transmission is a downshift, the command value of the torque control is offset so that the torque fluctuation associated with the shift-time magnetic force change control occurs on the plus side with respect to the actual torque output to the drive wheel. A control device for an electric vehicle that offsets a command value of the torque control so that when the shift of the automatic transmission is an upshift, the torque fluctuation occurs on the minus side with respect to the actual torque.

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