Control device of electric vehicle

Abstract

To enable efficient execution of magnetic force change control during travel and reduction of shift time.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. Gear change time magnetic force change control and fine slip control can be performed. The gear change time magnetic force change control is control of performing magnetic force change control of changing a magnetic force of the magnetic force variable magnet 35 during a gear change period of the automatic transmission 8. The fine slip control is control of causing any of a transmission clutch 83 to fine-slip at a predetermined rotation speed. By performing the fine slip control in a period of a pre-charge and holding phase in the gear change period of the automatic transmission 8, the first clutch before gear change is set to a state of being fine slipped.SELECTED DRAWING: Figure 17

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 that drive motor, a magnetic force variable magnet capable of variably changing the magnitude of the magnetic force 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. Thereby, 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 requested so that the clutch is fully engaged. Therefore, there is a concern that the fluctuating torque is directly transmitted to the drive wheels, generating a torque shock in the traveling vehicle and giving the driver a sense of discomfort.

[0005] 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 the torque shock can be alleviated.

[0006] However, when the clutch slips, a phenomenon occurs in which the rotation speed of the drive motor suddenly increases (so-called "runaway"). If such a runaway phenomenon is not quickly eliminated, there is a concern that the clutch may be damaged by 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] The technique generally switches from torque control that controls the torque required for output to power control that controls the power output as the target, when slip occurs in the clutch by increasing the magnetic force. Thereby, it becomes possible to converge not only the output torque but also 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] Control for changing the magnetic force of the magnet with variable magnetic force (magnetic force change control) was assumed to be executed 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 also assumed the off-target use of a transmission that is not shifting gears.

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

[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, torque shock may occur accordingly. However, with the additional torque shock of the magnetic force change control, there is a concern that it may cause not only discomfort to the driver but also additional 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 by making good use of this, it is possible to reduce slip loss.

[0014] In addition, from the perspective of comfortable driving, the gear shifting operation is preferably smooth and short in time. However, since the transmission is hydraulically controlled, there are physical constraints due to hydraulic control, and there is a limit to shortening the gear shifting time.

[0015] Specifically, when releasing the engaged clutch, it is only necessary to release the supplied hydraulic pressure, so it can be executed simply and in a short time. On the other hand, when engaging the released clutch, it is necessary to supply oil to the empty oil chamber and appropriately raise the hydraulic pressure to a predetermined value. Therefore, it cannot be executed as simply and in a short time as the release operation.

[0016] At that time, the fluidity of the oil also changes depending on the temperature of the oil and the air bite. Therefore, it is necessary to consider the worst hydraulic pressure responsiveness, and there is a limit to shortening the gear shifting time. Since it is a physical phenomenon, it was considered difficult to eliminate it.

[0017] On the other hand, the inventors have found that by further expanding the above-mentioned findings, it is possible to shorten the gear shifting time.

[0018] Therefore, this specification discloses a technique that enables magnetic force change control while achieving both suppression of torque shock and reduction of slip loss during automatic gear shifting of a vehicle, and also enables shortening of the gear shifting time.

Means for Solving the Problems

[0019] The disclosed technology relates to a control device for an electric vehicle capable of traveling using electric power, which includes a drive motor in which the magnetic poles of a rotor are configured by a magnet with variable magnetic force capable of changing the magnetic force, and an automatic transmission disposed between the drive motor and drive wheels and including a plurality of clutches.

[0020] The control device can execute a magnetic force change control for changing the magnetic force of the magnet with variable magnetic force during a shift period of the automatic transmission, which is a magnetic force change control during shifting, and a micro slip control for making any one of the clutches slip slightly at a predetermined rotational speed by executing rotational speed feedback control based on the differential rotational speed between the input side and the output side of the clutch.

[0021] The automatic transmission has a shift period including a pre-charge & hold phase for adjusting the hydraulic pressure of a predetermined first clutch before shifting and a predetermined second clutch after shifting so that the engagement torque of each is held in the vicinity of the transmission torque, a torque phase for switching the transmission of torque from the first clutch to the second clutch following the pre-charge & hold phase, and an inertia phase for switching to a rotational speed corresponding to the gear ratio from the first clutch to the second clutch following the torque phase.

[0022] Then, during the period of the pre-charge & hold phase, the first clutch is made to slip slightly by executing the micro slip control.

[0023] That is, according to this control device, it is possible to execute a magnetic force change control during shifting for changing the magnetic force of the magnet with variable magnetic force during the shift period of the automatic transmission, and a micro slip control for making any one of the clutches slip slightly by rotational speed feedback control.

[0024] If the clutch is slightly slipped by the micro-slip control before the magnetic force change control, although details will be described later, it becomes possible to suppress torque shock generated along with the magnetic force change control and reduce slip loss.

[0025] Then, if the micro-slip control is executed during the pre-charge & hold phase corresponding to the preparation stage of gear shifting to slightly slip the first clutch, it becomes possible to shorten the gear shift time, which has been considered difficult in the past.

[0026] That is, the length of the pre-charge & hold phase is substantially determined by the pressure increase operation of the second clutch, but the pressure increase operation is affected by variations in hydraulic pressure. For example, if the response of the hydraulic pressure is delayed, rotation surges may occur on the input side (driving side) of the first clutch.

[0027] Therefore, it is necessary to set the period of the pre-charge & hold phase in consideration of variations in hydraulic pressure so that such rotation surges do not occur. Therefore, the period of the pre-charge & hold phase has to be set with a certain margin and it is difficult to shorten it.

[0028] On the other hand, in this control device, during the period of the pre-charge & hold phase, micro-slip control for bringing the first clutch into a slightly slipped state is executed by performing rotational speed feedback control based on the differential rotational speed between the input side and the output side of the first clutch. Therefore, even if a delay in the response of the hydraulic pressure occurs due to variations in the hydraulic pressure, the first clutch is maintained in a slightly slipped state, so rotation surges can be prevented.

[0029] As a result, it becomes unnecessary to consider variations in hydraulic pressure, so the period of the pre-charge & hold phase, that is, the gear shift time can be shortened.

[0030] It may be that the magnetic force change control is executed during the inertia phase.

[0031] During the inertia phase, 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.

[0032] Therefore, by performing rotational speed feedback control using the slipping second clutch, minute slip control can be easily executed. As a result, the second clutch can be brought into a minute slip control state before the execution of the magnetic force change control, so that torque shock generated along with the magnetic force change control can be suppressed and slip loss can be reduced. Since slip associated with shifting is utilized, slip loss associated with the minute slip control can be reduced.

[0033] Specifically, the control device may be configured as follows.

[0034] When the electric vehicle is running, clutch full engagement control for making the engagement torque of the engaged clutch higher than the transmission torque is executed together with torque control for controlling the motor torque output by the drive motor so as to match the required torque required at the drive wheels.

[0035] In the case of non-shifting magnetic force change control for executing the magnetic force change control outside the shifting period of the automatic transmission, the clutch is put into a slipping state by reducing the engagement torque to near the transmission torque instead of the clutch full engagement control, and after executing the minute slip control in that state, the magnetic force change control is executed.

[0036] On the other hand, in the case of shifting magnetic force change control, the magnetic force change control is executed using the state where the second clutch is in minute slip.

[0037] That is, according to this control device, the magnetic force change control for changing the magnetic force of the magnet with variable magnetic force can be executed regardless of the gear shift of the automatic transmission. Therefore, the motor efficiency is increased. Moreover, torque shock can be suppressed and slip loss can also be reduced both inside and outside the gear shift period. Thereby, the driving comfort and fuel consumption (electricity cost) can be improved.

[0038] It is also possible to execute the magnetic force change control at the timing immediately after shifting from the torque phase to the inertia phase.

[0039] If the minute slip control is executed and continued during the pre-charge & hold phase, the second clutch can be held in a minute slip state during the torque phase. By doing so, even if the magnetic force change control is executed at the timing immediately after shifting to the inertia phase, torque shock can be suppressed and slip loss can be reduced.

[0040] And since the slip can be increased immediately after the start of the inertia phase, the synchronization of the rotational speed is further promoted. It becomes possible to effectively shorten the inertia phase, and the gear shift time can be stably shortened.

Advantages of the Invention

[0041] According to the disclosed technology, magnetic force change control can be executed while effectively suppressing torque shock and slip loss even during gear shift of the vehicle. Therefore, magnetic force change control can be performed without considering gear shift, so that the motor efficiency is increased. Thereby, the fuel consumption (electricity cost) of the vehicle can be improved. In addition, it becomes possible to shorten the gear shift time. Thereby, the driving comfort can also be improved.

Brief Description of the Drawings

[0042]

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Embodiments for Carrying Out the Invention

[0043] <Electric Vehicle> Figure 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 running 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 runs. Note that the automobile 1 may be an electric vehicle equipped with only the drive motor 3. The automobile 1 may also be four-wheel drive.

[0044] In the case of this automobile 1, the engine 2 is arranged on the front side of the vehicle body, and the drive wheels 4R are arranged 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.

[0045] In addition to the engine 2 and the drive motor 3, the automobile 1 is equipped with a relay clutch 5, an inverter 6, an automatic transmission 8, a differential gear 9, a battery 10, etc. as devices of the drive system. The automobile 1 is also equipped with 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. as devices of the control system. 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 automobile 1 attached to the devices of the control system.

[0046] (Devices of 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, etc., but in the disclosed technology, the type and form of the engine are not particularly limited.

[0047] In this motor vehicle 1, the engine 2 is arranged at substantially the center in the vehicle width direction with its output shaft for outputting rotational power facing the longitudinal direction of the vehicle body. Various devices and mechanisms associated with the engine 2, such as an intake system, an exhaust system, and a fuel supply system, are installed in the motor vehicle 1, but the illustration and description of these are omitted.

[0048] The drive motor 3 is arranged in series behind the engine 2 via a relay clutch 5. The drive motor 3 is a permanent magnet type synchronous motor driven by three-phase alternating current. As shown schematically in FIG. 2, the drive motor 3 is generally composed of a motor case 31, a shaft 32, a rotor 33, a stator 34, etc.

[0049] The motor case 31 is a container having a cylindrical space with its front end face and rear end face sealed inside, and is fixed to the vehicle body of the motor vehicle 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.

[0050] A relay 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 relay 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).

[0051] The rear end 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.

[0052] The rotor 33 is composed of 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.

[0053] Magnets 35 are installed over the entire circumference on the 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 one cylindrical magnet having a plurality of magnetic poles, or may be composed of a plurality of arc-shaped magnets constituting each magnetic pole.

[0054] In this drive motor 3, further, the magnets 35 are configured so that the magnitude of the magnetic force can be variably increased or decreased (magnetic force variable magnets 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.

[0055] Permanent magnets include various types such as ferrite magnets, neodymium magnets, samarium cobalt magnets, and alnico magnets, and their holding forces also vary. The type and material of the magnetic force 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 magnetic force variable magnets 35, and permanent magnets may be included.

[0056] 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 formed by laminating a plurality of metal plates and a plurality of coils 36 formed by winding electric wires around the stator core 34a.

[0057] The stator core 34a is provided with a plurality of teeth 34b that radially project inward. By winding an electric wire around these teeth 34b in a predetermined order, a plurality of coils 36 are formed. 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.

[0058] To energize each phase's 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.

[0059] 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.

[0060] In the case of this automobile 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). The other end of the automatic transmission 8 has an output shaft 81 that rotates independently of the input shaft 80.

[0061] Between these input shaft 80 and output shaft 81, a transmission mechanism including 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.

[0062] By switching these transmission mechanisms, it is configured such that forward or reverse can be switched, and the rotational speed can be changed to different values between the input shaft 80 and the output shaft 81 of the automatic transmission 8, that is, the gear ratio can be switched.

[0063] 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.

[0064] 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 gear ratio and the like are switched.

[0065] The output shaft 81 is connected to the differential gear 9 via the 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.

[0066] 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. A brake 14 is attached to each wheel 4F, 4F, 4R, 4R to brake its rotation.

[0067] (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.

[0068] 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, and BCU 23 and comprehensively controls them.

[0069] 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.

[0070] The engine rotation sensor 50 is attached to the engine 2, detects the rotation 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 rotation speed and rotation 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.

[0071] The magnetic sensor 53 is attached to the drive motor 3, detects the magnetic force of the magnet with variable magnetic force 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.

[0072] Based on the signals of the detection values input from these sensors, each unit collaborates to control each device of the drive system, enabling the vehicle 1 to run. For example, when the vehicle 1 runs 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.

[0073] 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 a non-engaged state or a 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 power to be recovered by the battery 10.

[0074] Fig. 3 shows the TCU 22 and the main input / output devices related thereto. Functionally, the TCU 22 is provided with a relay clutch control unit 22a and a transmission clutch control unit 22b by its hardware and software. 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 transmission clutch 83.

[0075] <Control of the drive motor> The MCU 21 controls the vehicle 1 to run using the power output by the drive motor 3 in a state where the drive motor 3 outputs alone or, if necessary, in a state of assisting the output of the engine 2.

[0076] 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.

[0077] Fig. 4 shows the MCU 21 and the main input / output devices related thereto. As a functional configuration, the MCU 21 is provided with a motor output control unit 21a and a magnetization control unit 21b by its hardware and software.

[0078] The motor output control unit 21a has a function of controlling the drive of the drive motor 3, and by controlling the drive current flowing through the coil 36, causes the drive motor 3 to output the required power. On the other hand, the magnetization control unit 21b changes the magnetic force of the magneto - variable magnet 35 by controlling the magnetization current flowing through the coil 36.

[0079] 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.

[0080] Furthermore, the output range of the drive motor 3 is partitioned into a plurality of magnetization regions. And according to each of these magnetization regions, the magnetization control unit 21b is configured to change the magnetic force of the magneto - variable magnet 35. That is, when the magnetization region shifts to another adjacent magnetization region, the magnetization control unit 21b changes the magnetic force of the magneto - variable magnet 35 to the magnetic force optimum value corresponding to that magnetization region.

[0081] (Specific Example of Driving Motor Control) Figure 5 shows a simplified system diagram regarding the control of the driving motor 3. Figure 6 shows an example of the control of the driving motor 3 performed by the MCU 21. With reference to these, the specific control flow of the driving motor 3 will be described. Note that the driving motor 3 is controlled by vector control using the torque current command Iq * and the excitation current command Id * .

[0082] When the vehicle 1 becomes in a drivable state, the MCU 21 will constantly receive the detected values from the current sensor 52, the motor rotation sensor 51, and the magnetic force sensor 53 (step S1). Similarly, the ECU 20 will also constantly receive the detected values from the accelerator sensor 54 and the engine rotation sensor 50

[0083] The GCU 24 obtains the detected value of the accelerator sensor 54 from the ECU 20, and according to the preset output distribution ratio between the engine 2 and the driving motor 3, sets the torque required for the driving motor 3 (required torque) among the torque output to the drive wheels 4R. The GCU 24 outputs a command (torque command value T * ) to the MCU 21

[0084] That is, the MCU 21 controls the output of the driving motor 3 based on a predetermined target torque (so-called torque control). By torque control, the torque (motor torque) output by the driving motor 3 is controlled to match the target torque. Therefore, when the above command is input while the vehicle 1 is running, the MCU 21 controls the driving motor 3 with the required torque as the target torque. By the torque control of the driving motor 3, the vehicle 1 runs according to the driver's request

[0085] During the operation of this vehicle 1, when shifting the magnetization region as described above, 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 magnetically variable magnet 35 is changed.

[0086] Specifically, when the torque command value T * is input (Yes in step S2), the MCU 21 (motor output control unit 21a) 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 magnetically variable magnet 35 based on the magnetization state command value Φ * ) (step S5).

[0087] The MCU 21 determines whether it is necessary to change the magnetic force of the 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 magnetically variable magnet 35, and when the required torque is output and it is located in the same magnetization region, it is determined that it is not necessary to change the magnetic force of the magnetically variable magnet 35.

[0088] 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.

[0089] That is, the motor output control unit 21a performs calculation 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).

[0090] When the switching command value is output 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 (driving current) is supplied to each coil group, and the driving motor 3 rotates with the required torque (step S10).

[0091] 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), magnetic force change control is executed by the magnetization control unit 21b (step S11).

[0092] 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 is determined that the output torque is equal to or less than the torque T1 at which the driving motor 3 runs idle (No in step S7), magnetic force change control is executed by the magnetization control unit 21b (step S11).

[0093] That is, when the required amount of rotational power of the driving motor 3 becomes almost 0 (zero), the magnetic force of the magnetically variable magnet 35 is changed (reset) to its initial state. 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 stop state.

[0094] In the case of the magnetically 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 is performed, the driving motor 3 can be appropriately driven.

[0095] Fig. 7 shows the main processing flow of magnetic force change control. When magnetic force change control is requested, the magnetization control unit 21b 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 magnetically variable magnet 35 (magnetic flux increasing process) or a process of decreasing the magnetic force of the magnetically variable magnet 35 (magnetic flux decreasing process). The magnetization control unit 21b further specifies the amount of change in the increasing or decreasing magnetic force.

[0096] Then, the magnetization control unit 21b determines whether the position of the rotor 33 relative to the stator 34 (position in the rotational direction) is at a position suitable for the magnetization process based on the detected value of the motor rotation sensor 51 (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 magnetically 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.

[0097] The magnetization control unit 21b determines whether the magnetic force of the magnetically 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 magnetically variable magnet 35 becomes approximately the same as the magnetic force optimum value. When resetting the magnetic force of the magnetically variable magnet 35, the magnetization process is executed until it becomes approximately the same as the initial magnetic force.

[0098] When the magnetic force of the magnetically variable magnet 35 becomes approximately the same as the magnetic force optimum 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).

[0099] <Control of the transmission clutch> As described above, in this vehicle 1, magnetic force change control is also executed during the operation of the vehicle 1. When magnetic force change control is executed during the operation of the vehicle 1, there is a concern that a torque shock will occur in the running vehicle 1, giving the driver a sense of discomfort.

[0100] The upper diagram of FIG. 8 illustrates the change over time of the motor torque Tm during magnetic force change control. In this illustration, a field weakening process (an example of 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.

[0101] That is, while confirming the change in magnetic force, control (learning control) is executed to cause the drive current value (the value of the q-axis current) to be learned so as to correspond to the magnetic force after field weakening. The learning control is control associated with the change in magnetic force and is included in the magnetic force change control. While the vehicle 1 is running, since the drive motor 3 is under torque control, the motor torque Tm before and after the execution of the magnetic force change control matches the required torque Ta.

[0102] 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 raised, the clutch engagement torque Tt becomes larger.

[0103] In order to reliably transmit the motor torque Tm to the drive wheels 4R, normally, 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 is at least 500 kPa or more.

[0104] 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 also match the required torque Ta.

[0105] During magnetic force change control, in order to generate a large electromagnetic force, a magnetization current (d-axis current) is passed through coil 36. As a result, a high voltage far exceeding the drive voltage is applied to drive motor 3. Therefore, as shown in the upper diagram of Fig. 8, during magnetic force change control, a peak-like high motor torque Tm far exceeding the required torque Ta is output from drive motor 3. As a result, under clutch full engagement control, a torque shock is generated in the traveling automobile 1, raising concerns about discomfort for the driver.

[0106] On the other hand, when performing magnetic force change control, if the transmission clutch 83 is slipped, such torque shock can be suppressed. That is, as shown in the upper diagram of Fig. 8, during the period before and after magnetic force change control, the hydraulic pressure supplied to the automatic transmission 8 is lowered. By doing so, the clutch engagement torque Tt is reduced, and control is performed so that the clutch engagement torque Tt substantially matches the required torque Ta.

[0107] Specifically, as shown in the upper diagram of Fig. 8, immediately before the start (time t1) of magnetic force change control (time t0), instead of 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 drive motor 3 by 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 magnetic force change can be suppressed.

[0108] (Rotation surge) However, when the transmission clutch 83 is slipped, a phenomenon occurs in which the rotation of drive motor 3 suddenly increases (so-called "surge").

[0109] The lower diagram of FIG. 8 shows the relationship between the motor torque Tm and the motor speed during magnetic force change control. Here, the output of the engine 2 is not considered. Therefore, the motor speed is also the rotational speed of the input shaft 80 of the automatic transmission 8. Further, 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.

[0110] Before the execution of the magnetic force change control, the drive motor 3 is rotating at a predetermined rotational 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 rotational speed Ra. Note that the output shaft 81 of the automatic transmission 8 is rotating at a rotational speed shifted by the planetary gear mechanism 82 corresponding to the transmission clutch 83.

[0111] When the transmission clutch 83 is effectively slipped during the magnetic force change control, the drive motor 3 will be in a free rotation state, so the motor speed will suddenly increase from the rotational speed Ra corresponding to the required torque Ta. It will further increase during the learning control, and the motor speed will reach a high-stop state. If this soaring phenomenon is not eliminated promptly, the transmission clutch 83 may be damaged due to the frictional heat caused by the slip.

[0112] (Micro-slip control) As described above, in order to suppress the torque shock caused by the magnetic force change control, it is necessary to slip the transmission clutch 83. For this purpose, it is necessary to significantly reduce the hydraulic pressure supplied to the automatic transmission 8 from the hydraulic pressure during the clutch full-engagement control and lower the clutch engagement torque.

[0113] Fig. 9 illustrates the torque characteristics (transmission torque characteristics) transmitted in a state where the clutch engagement torque is reduced to near the transmission torque. The vertical axis represents the output torque (Tout), and the horizontal axis represents 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 where the hydraulic pressure is 210 kPa, and Graph G3 represents the case where the hydraulic pressure is 190 kPa.

[0114] As shown in Graphs G1 - G3, the transmission torque characteristics vary according to the hydraulic pressure. However, for the same clutch, even if the hydraulic pressures are different, they have the same form of transmission torque characteristics. 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).

[0115] 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 are the same value. That is, the transmission clutch 83 is in an engaged state, and all 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 except for a part of the input torque is transmitted and output.

[0116] 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 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).

[0117] In other words, in the case of the transmission clutch 83 having such transmission torque characteristics, 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.

[0118] Thus, for example, while performing hydraulic pressure control so that the clutch engagement torque Tt (corresponding to the upper limit transmission torque) coincides with 45 Nm, 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 eliminated, and torque shock can be suppressed.

[0119] 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 becomes equal to or less than a predetermined value (for example, 100 rpm or less), both torque shock and slip loss can be minimized.

[0120] 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.

[0121] Specifically, the TCU 22 (transmission clutch control unit 22b) slips the transmission clutch 83 by reducing 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.

[0122] For example, when 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 characteristic of the transmission clutch 83 becomes 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 rotation speed of about 20 rpm.

[0123] Then, feedback control based on the clutch differential rotation speed (rotation 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 rotation speed, and the micro slip state is maintained.

[0124] If the transmission clutch 83 starts the magnetic force change control in the 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 suppression of torque shock and suppression of slip loss.

[0125] <Expansion of the Execution Region of the Magnetic Force Change Control> The magnetic force change control was assumed to be executed 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 use in order to execute the micro slip control.

[0126] 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 greatly 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.

[0127] Therefore, from the perspective of suppressing fuel consumption (electricity cost), it is assumed that there are cases where magnetic force change control must be executed not only outside the shift period of the automatic transmission 8 but also during the shift 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 shift period. And if the magnetic force change control can be executed even during the shift period, the magnetic force can be changed without considering the shift, so the motor efficiency will be further increased.

[0128] 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 shift 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.

[0129] Fig. 10 shows a flowchart that is the basis of the 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 operation of the vehicle 1 (step S31). And when it is determined that the magnetic force change control is to be executed, it is determined whether the magnetic force change control is to be executed during the shift period, that is, during the shift of the automatic transmission 8 (step S32).

[0130] As a result, when the execution of the magnetic force change control is not during the shift period, that is, when it is outside the shift period (No in step S32), as described above, the magnetic force change control for using the automatic transmission 8 for other purposes (magnetic force change control during non-shifting) is executed (step S33). On the other hand, when the magnetic force change control is during the shift period (Yes in step S32), the magnetic force change control corresponding to the state change during the shift of the automatic transmission 8 (magnetic force change control during shifting) is executed (step S34).

[0131] In addition, depending on the situation, even when the magnetic force change control can be executed outside the shift time, it may be possible to wait for the timing when the automatic transmission 8 shifts and execute the magnetic force change control during the shift period.

[0132] (Specific example of magnetic force change control during non-shifting) Fig. 11 shows a specific example (time chart) of magnetic force change control (non-shifting magnetic force change control) executed outside the shifting 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 micro slip control described above.

[0133] 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.

[0134] The middle part is a time chart regarding the torque of the transmission clutch 83. The dashed line L1 represents the input torque, the double-dashed line L2 represents the output torque, the solid line L3 represents the clutch engagement torque, and the dash-dotted line L4 represents the upper limit transmission torque.

[0135] The lower part is a time chart regarding the clutch differential rotation speed. It represents the difference between the rotation speed of the input side 83a and the rotation speed of the output side 83b of the transmission clutch 83.

[0136] As shown in Fig. 12, when the control device (MCU21) determines that the magnetic force change control is to be executed outside the shifting 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.

[0137] 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 rotation speed increases.

[0138] Then, the MCU 21 starts the pre-stage feedback control so as to converge to a predetermined minute slip state (step S43). Specifically, based on the detection value of the transmission sensor 55, 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 actually measured or estimated becomes equal to or less than the target differential rotational speed Rs (step S44). That is, the pre-stage feedback control corresponds to the "rotational speed feedback control" in the disclosed technology.

[0139] If it is the rotational speed of the drive motor 3, it can be controlled with relatively high accuracy. Also, the clutch differential rotational speed can be quickly converged 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, respectively (t1 to t2).

[0140] In such a state, the MCU 21 starts the magnetic force change control (step S45). When the magnetic force change control is executed, as described above, a high motor torque is instantaneously output from the drive motor 3, and the torque is added to the input torque (t2 to t3).

[0141] 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 sense it. Therefore, the torque shock can be effectively suppressed.

[0142] Torque fluctuations also occur immediately after the magnetic force change control, 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 drive wheels, here the same as the required torque or the output torque, 43 Nm).

[0143] This post-torque shock converges by the learning control described above, but it takes several milliseconds to several tens of milliseconds to converge. Therefore, there is a concern that although it is momentary, it may give the driver a sense of discomfort.

[0144] When the post-torque shock occurs on the positive side, it can be regulated by the upper limit transmission torque. On the other hand, when the post-torque shock occurs on the negative side as shown in the illustrated example, it is output as a shock (pull-in shock) that pulls it in as it is. Therefore, from the viewpoint of suppressing torque shock, it is preferable that the post-torque shock occurs on the positive side with respect to the actual torque.

[0145] Therefore, in this embodiment, the command value of torque control (here, the same as the required torque) during non-shifting magnetic force change control is offset by a predetermined amount considering the variation range 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.

[0146] Although the clutch differential rotational speed also shows a slight increase, it can be suppressed to 100 rpm or less, which is the allowable level. Therefore, slip loss can also be effectively suppressed.

[0147] The MCU 21 determines whether or not 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).

[0148] In power control, torque control is executed so that the power output from the drive wheel 4R, that is, the multiplication value of the torque T and the rotational speed R of the drive wheel 4R, becomes a predetermined target power value (target power value) (t3 to t4). 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.

[0149] If the target power value is constant, when the motor speed Rm is high, the target torque decreases accordingly, and when the motor speed Rm is low, the target torque increases accordingly. Therefore, according to power control, unlike torque control, both the speed and torque can be adjusted in a well-balanced manner. As a result, the transmission clutch 83, whose speed and torque have become unstable due to magnetic force change control, quickly converges to a slight slip state.

[0150] When a predetermined period elapses and the clutch differential speed reaches a predetermined differential speed Rf greater than the target differential speed Rs (Yes in step S48), the MCU21 starts the subsequent feedback control (step S49). Specifically, the rotation speed of the input side, that is, the rotation speed output by the drive motor 3, is adjusted so that the clutch differential speed converges to the target differential speed Rs (step S50). Thereby, the clutch differential speed can converge to the target differential speed Rs more quickly and can be maintained in a slight slip state (t4~t5).

[0151] Thereafter, the TCU22 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 MCU21 resumes normal torque control (step S52).

[0152] Note that the power control after the end of the magnetic force change control may be omitted, and immediately, the subsequent feedback control with the target differential speed Rs set to 0 (zero) may be entered. In that case, as shown by the virtual line Ln in FIG. 11, the clutch differential speed can be eliminated in an extremely short time, and the slip loss can be further suppressed.

[0153] (State changes during gear shifting of the automatic transmission) Prior to the description of a specific example of the magnetic force change control (magnetic force change control during gear shifting) executed during the gear shifting 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.

[0154] Fig. 13 illustrates a time chart of the main specifications (vehicle speed, vehicle acceleration, input torque, engine speed, engagement torque) during the shift of the automatic transmission 8. Here, the vehicle 1 is traveling only under 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. By the shift, the engine speed of the engine 2 is switched from the first gear to the second gear.

[0155] In the automatic transmission 8, a shift is made from the first clutch (transmission clutch 83 corresponding to the first gear before the shift) to the second clutch (transmission clutch 83 corresponding to the second gear after the shift). That is, the engaged state and the released state are switched between the first clutch and the second clutch.

[0156] The shift period of the automatic transmission 8 generally consists of a period including a pre-charge & hold phase, a torque phase, and an inertia phase from the content of the state change.

[0157] The pre-charge & hold phase corresponds to the preparation stage of the shift. 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 the shift, the pre-charge & hold phase suppresses the response delay of the hydraulic pressure.

[0158] The period of the pre-charge & hold phase also makes the release operation of the first clutch smooth and prompt. 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. Note that the state change of the pre-charge & hold phase will be described separately later.

[0159] 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 reduced from the standby state near the transmitted torque, causing the clutch 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 transmitted torque, causing the clutch to shift from the released state to the engaged state.

[0160] During the torque phase, both the first clutch and the second clutch are in a slipping state while maintaining the input torque caused by the driving of the engine 2 through torque control. The first clutch slips while decreasing the rotational speed, and the second clutch slips while increasing the rotational speed.

[0161] During this period, hydraulic pressure feedback control based on the clutch differential rotational speed is executed for the second clutch. As a result, the hydraulic pressure of the second clutch gradually increases according to the decrease in the hydraulic pressure of the first clutch.

[0162] Therefore, the transmission of torque is smoothly switched from the first clutch to the second clutch while maintaining a constant magnitude of the transmitted torque. When the first clutch becomes the released state and the transmission of torque is completely switched from the first clutch to the second clutch, the torque phase shifts to the inertia phase.

[0163] 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 from that rotational speed to the rotational speed corresponding to the gear ratio of the second clutch is performed. Note that the rotational speed on the output side during the shifting period hardly changes due to inertia.

[0164] 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 is smaller for the second clutch than for the first clutch. And the input torque due to the driving of engine 2 is maintained by torque control. Therefore, the rotational speed of engine 2 gradually decreases.

[0165] At this time, in the second clutch, the relatively low-rotation input-side friction element slides with respect to the relatively high-rotation output-side friction element, causing it to slip. As a result, the input torque of drive motor 3 decreases. That is, it is in a state similar to when a draw-in shock occurs.

[0166] The slip of the second clutch gradually decreases. Then, when the slip disappears and the rotation synchronizes 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.

[0167] After the end of the inertia phase, by supplying hydraulic pressure to automatic transmission 8, clutch full engagement control for the second clutch is performed, and the gear shift of automatic transmission 8 is completed.

[0168] (Specific Example of Magnetic Force Change Control During Gear Shift) As described above, during the gear shift of automatic transmission 8, there is a period when transmission clutch 83 is slipping. 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.

[0169] That is, during the gear shift period of automatic transmission 8, transmission clutch 83 is slipping during the pre-charge & hold phase, the torque phase, and the inertia phase. Among them, magnetic force change control is executed during the inertia phase.

[0170] The period of the pre-charge & hold phase is a preparation period for shifting, aiming to suppress the response delay of hydraulic pressure. Therefore, the period of the pre-charge & hold phase is not suitable for executing magnetic force change control, and there is no such time margin either.

[0171] Also, during the torque phase, both the first clutch and the second clutch are slipping, and torque transmission is switched while maintaining the input torque by torque control. Therefore, from the perspective of control stability, it is not preferable to repeatedly execute magnetic force change control.

[0172] On the other hand, as described above, during the inertia phase, the switching from the first clutch to the second clutch has substantially ended, and the second clutch is slipping with the engagement torque reduced to near the transmission torque.

[0173] That is, the period of the inertia phase is in a state similar to the stage 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 shifting is utilized, the slip loss associated with the micro-slip control can also be reduced.

[0174] Among the period of the inertia phase, 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 vicinity thereof, and at least the period before the middle thereof.

[0175] By doing so, the torque generated due to the magnetic force change control can be added to the second clutch that is slipping during the torque phase, thereby increasing the slip. As a result, the synchronization of the rotational speed is promoted. It becomes possible to shorten the period of the inertia phase and the shifting period. If the period of the inertia phase is shortened, the slip loss is further reduced.

[0176] For example, when the shift of the automatic transmission 8 is 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 shifting occurs on the plus side with respect to the actual torque.

[0177] When the shift is downshift, the gear ratio of the second clutch is larger than that of the first clutch. Therefore, the rotational speed of the engine 2 gradually increases. At this time, in the second clutch during the inertia phase, the relatively high-rotating input-side friction element slides relative to the relatively low-rotating output-side friction element, resulting in slip. 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.

[0178] Therefore, similar to the suppression of the post-torque shock during non-shifting magnetic force change control, it is preferable to offset the command value of the torque control during shifting by a predetermined amount (for example, +15 Nm) considering the variation range. By doing so, the torque shock will always occur on the plus side, eliminating the pull-in shock and effectively suppressing the torque shock. Moreover, since the period of the inertia phase can be shortened, the slip loss can also be effectively reduced.

[0179] On the other hand, when the shift is upshift, 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 shifting occurs on the minus side with respect to the actual torque.

[0180] That is, the period of the inertia phase during upshift is in a state similar to when a pull-in shock occurs as described above. Therefore, contrary to the suppression of the post-torque shock during non-shifting magnetic force change control, the command value of the torque control during shifting is offset by a predetermined amount considering the variation range to the minus side (for example, -15 Nm).

[0181] If so, torque shock will always occur on the negative side, so that the synchronization of the rotational speed of the second clutch can be promoted, and the period of the inertia phase can be further shortened. Thereby, slip loss can be reduced more effectively.

[0182] FIG. 14 shows a specific example (time chart) of the magnetic force change control during gear shifting 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.

[0183] 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 forward feedback control so that the second clutch converges to a predetermined minute slip state (step S62). Then, the rotational speed of 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 forward feedback control corresponds to the "rotational speed feedback control" in the disclosed technology.

[0184] In such a state, the MCU 21 starts the magnetic force change control (step S64). Thereby, at the time of upshifting, as indicated by arrow A in FIG. 14, torque shock occurs in a state of being overlaid on the negative side. Therefore, the slip of the second clutch increases, and the synchronization of the rotational speed of the second clutch is promoted.

[0185] 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). Thereby, 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.

[0186] When the predetermined period has elapsed and the clutch differential rotation speed reaches a predetermined differential rotation speed Rf that is greater than the target differential rotation speed Rs (Yes in step S67), the MCU 21 starts the subsequent-stage feedback control (step S68). Specifically, the input rotation speed is adjusted so that the clutch differential rotation speed becomes 0 (zero), that is, the rotation speeds of the input side and the output side of the second clutch are synchronized (step S69).

[0187] As a result, as shown by arrow A2 in FIG. 14, the period of the inertia phase (shift period) is shortened compared to normal shifting. Not only can magnetic force change control be enabled during shifting, but also suppression of shocks associated with magnetic force change control and reduction of slip loss can be effectively achieved.

[0188] It is also possible to omit the power control after the magnetic force change control and immediately shift to the subsequent-stage feedback control with the target differential rotation speed Rs set to 0 (zero). By doing so, the clutch differential rotation speed can be eliminated in an extremely short time, and slip loss can be further suppressed.

[0189] <Application of Micro Slip Control to Shifting> From the perspective of driving comfort, the shifting operation is preferably smooth and short in time. However, since the automatic transmission 8 is hydraulically controlled, there are physical constraints due to hydraulic control, and there is a limit to shortening the shift time.

[0190] Specifically, during the pre-charge & hold phase, when shifting the clutch engagement torque of the engaged first clutch to near its transmission torque, the supplied hydraulic pressure may be removed. Therefore, it can be executed simply and in a short time.

[0191] On the other hand, when shifting the released second clutch to near its transmission torque, it is necessary to supply oil to the empty oil chamber and appropriately increase the hydraulic pressure to a predetermined value. Therefore, it cannot be executed as simply and in as short a time as the first clutch. Although at the level of several milliseconds, a response delay may occur.

[0192] At that time, the responsiveness also changes depending on the temperature of the oil and the air bite. For example, the oil in the cold state has high viscosity and its fluidity decreases, and even if there is an air bite immediately after startup, the fluidity of the oil decreases. That is, in the case of hydraulic control, since the hydraulic pressure varies, it is necessary to perform hydraulic control in consideration of its influence.

[0193] The upper diagram in FIG. 16 shows an enlarged time chart of the precharge & hold phase. The thick broken line H1 represents the change in the target hydraulic pressure (actual hydraulic pressure) of the first clutch. The thick solid line H2 represents the change in the target hydraulic pressure (actual hydraulic pressure) of the second clutch. The thin broken line h1 is the set hydraulic pressure (first set hydraulic pressure) in the hydraulic control of the first clutch, and the thin solid line h2 is the set hydraulic pressure (second set hydraulic pressure) in the hydraulic control of the second clutch. The actual hydraulic pressure is realized by the set hydraulic pressure.

[0194] During the precharge & hold phase, the first set hydraulic pressure is set to be the hydraulic pressure that makes the clutch engagement torque of the first clutch close to its transmission torque. Since it is a pressure reduction operation, even if there is a slight difference in the fluidity of the oil, the hydraulic pressure of the first clutch can be smoothly adjusted to the first set hydraulic pressure in a relatively short time. By reaching the first set hydraulic pressure, the friction elements of the first clutch enter a predetermined standby state.

[0195] Similarly, the second set hydraulic pressure is the hydraulic pressure that makes the clutch engagement torque of the second clutch close to its transmission torque during the precharge & hold phase. However, since it is a pressure increase operation, in order to suppress the response delay of the hydraulic pressure, it is set in two stages: the precharge phase t1 and the hold phase t2.

[0196] The precharge phase t1 is set to a predetermined hydraulic pressure (precharge hydraulic pressure) higher than the second set hydraulic pressure. Thereby, most of the oil chamber of the second clutch is filled with oil in a short time. The subsequent hold phase t2 is set to the second set hydraulic pressure. Thereby, oil flows gently into the oil chamber, and the clutch engagement torque of the second clutch is smoothly increased to near its transmission torque.

[0197] Thus, when the second set hydraulic pressure is reached, the friction elements of the second clutch enter the zero-touch state described above. However, unlike the first clutch, the hydraulic pressure control of the second clutch is affected by variations in hydraulic pressure. That is, if the fluidity of the oil changes, the time (pressure build-up completion time) to reach the second set hydraulic pressure will vary accordingly, becoming slower or faster. As a result, when the pressure build-up completion time is short, the engagement shock becomes large, and when the pressure build-up completion time is long, "rotation surge" occurs.

[0198] Below Figure 16, the portion where the transition from the pre-charge & hold phase to the torque phase is shown enlarged. When there is no variation in hydraulic pressure, i.e., when it is as per the target, the transition from the pre-charge & hold phase to the torque phase occurs at the timing indicated by arrow P. When the torque phase is initiated, as described above, the hydraulic pressure of the first clutch gradually decreases, and correspondingly, in the second clutch, the hydraulic pressure gradually increases by hydraulic pressure feedback control. Therefore, the transmitted torque is kept constant.

[0199] On the other hand, when the pressure build-up completion time becomes short, as shown by the dashed line H2a, the rise of the actual hydraulic pressure of the second clutch speeds up, and the hydraulic pressure of the second clutch rises before the decrease in the hydraulic pressure of the first clutch. As a result, the transmitted torque of the second clutch becomes excessive compared to the target, and the engagement shock becomes large. However, the engagement shock itself can occur even if the hydraulic pressure does not vary as described earlier.

[0200] On the other hand, when the pressure build-up completion time becomes long, as shown by the dotted-dashed line H2b, the rise of the actual hydraulic pressure is delayed, and the hydraulic pressure of the first clutch decreases before the rise of the hydraulic pressure of the second clutch. As a result, rotation surge occurs on the input side of the first clutch.

[0201] When the engine 2 is driven, the engine speed will surge. Therefore, suppressing this rotation surge is more important than suppressing the engagement shock.

[0202] Therefore, in order to prevent such a delay in the rise of the actual hydraulic pressure, it was necessary to consider the worst hydraulic response delay, and there was a limit to shortening the period of the pre-charge & hold phase. Since it is a physical phenomenon, it was considered difficult to solve this problem.

[0203] On the other hand, the inventors have found that if the above-mentioned findings are further extended, it is possible to shorten the shift time. That is, by applying the micro-slip control utilized for both suppressing the torque shock associated with the magnetic force change control and reducing the slip loss during the pre-charge & hold phase, it has been found that the period of the pre-charge & hold phase can be shortened.

[0204] Specifically, during the period of the pre-charge & hold phase, by executing the micro-slip control, the rotational speed of the first clutch is controlled. That is, by executing the rotational speed feedback control based on the clutch differential rotational speed of the first clutch, the first clutch is controlled to converge to a predetermined rotational speed.

[0205] By doing so, even if the rise of the actual hydraulic pressure of the second clutch is delayed and the hydraulic pressure of the first clutch drops before the rise of the hydraulic pressure of the second clutch, the first clutch is held in a state of slight slip. Therefore, it is possible to prevent the rotation from surging on the input side of the first clutch.

[0206] (Improved Shift Control) FIG. 17 shows a specific example of a shift control (improved shift control) that enables shortening of the shift time by applying the micro-slip control during the period of the pre-charge & hold phase.

[0207] Before the start of shifting of the automatic transmission 8, the first clutch is in a fully engaged state, and the second clutch is in a fully released state. Therefore, the first clutch and the second clutch are not slipping.

[0208] When the shift of the automatic transmission 8 starts, the TCU 22 reduces the hydraulic pressure of the first clutch to near its transmission torque based on its transmission torque characteristics (step S80). Since this is a pressure reduction operation, it can be executed smoothly in a short time. Thereby, the friction elements of the first clutch enter the standby state of the torque phase.

[0209] Subsequently, the MCU 21 starts micro-slip control (step S81). That is, rotation speed feedback control is started so that when the first clutch slips, it converges to a predetermined micro-slip state.

[0210] Specifically, based on the detected value of the transmission sensor 55, the rotation speed of the input side of the first clutch is adjusted by the drive motor 3 and / or the engine 2 so that the clutch differential rotation speed of the first clutch, which is actually measured or estimated, becomes equal to or less than the target differential rotation speed Rs (for example, 20 rpm). At this time, the driving of the vehicle 1 is controlled by the transmission torque of the first clutch.

[0211] Then, the TCU 22 starts supplying hydraulic pressure to the second clutch (step S82). That is, the clutch engagement torque of the second clutch is boosted to near its transmission torque. Then, the TCU 22 activates a hydraulic pressure holding timer that counts a predetermined holding time ts (step S83). The holding time ts is the time when the second clutch becomes the zero-touch state.

[0212] Under the standard conditions (such as during warm-up) where the fluidity of the oil is appropriate, the second clutch becomes the zero-touch state in about 0.3 milliseconds. However, a delay occurs under the worst conditions (such as during cold start) where the fluidity of the oil is low. Therefore, conventionally, the holding time ts was set to a time obtained by adding the delay to the standard conditions. In contrast, in this improved shift control, it is not necessary to consider the delay. That is, the holding time ts can be set to the time of the standard conditions itself. The shift time can be shortened compared to the conventional method.

[0213] When the holding time ts is reached, the TCU 22 shifts to the torque phase (steps S84, S85). Depending on the situation, the supply of hydraulic pressure to the second clutch and the operation of the hydraulic pressure holding timer may start at the same timing as the start of the micro slip control. For example, steps S81 to S83 may be almost simultaneous.

[0214] When shifting to the torque phase, as described above, the torque transmission is switched from the first clutch to the second clutch. By continuing the micro slip control, in response to the switching of the torque transmission, the target of the micro slip control also shifts from the first clutch to the second clutch. That is, during the torque phase, the first clutch and the second clutch are held in a micro slip state.

[0215] The TCU 22 determines whether the torque phase has ended (step S86). Then, when it is determined that the torque phase has ended, the TCU 22 determines whether to execute magnetic force shift control (magnetic force shift control during shifting) (step S87).

[0216] If it is determined not to execute the magnetic force shift control (No in step S87), the MCU 21 ends the micro slip control, and the TCU 22 shifts to the normal inertia phase (step S88). Thus, according to the improved shift control applying the micro slip control, it becomes possible to shorten the shift time, which has been considered difficult in the past.

[0217] On the other hand, if it is determined to execute the magnetic force shift control (Yes in step S87), the TCU 22 shifts to the inertia phase with magnetic force shift control (step S89). As described above, during the torque phase, the second clutch is held in a micro slip state. Therefore, the magnetic force shift control can be executed using that state. That is, it is possible to suppress torque shock and reduce slip loss.

[0218] Moreover, in this case, unlike the magnetic force shift control during shifting described above, the second clutch is already in a slight slip state during the torque phase. That is, it is not necessary to start the slight slip control during the inertia phase and wait for convergence to the slight slip state.

[0219] Therefore, it is preferable to execute the magnetic force shift control at the timing immediately after shifting from the torque phase to the inertia phase. That is, even if the magnetic force shift control is executed at the timing simultaneous with the start of the inertia phase, torque shock can be suppressed and slip loss can be reduced. Therefore, the shortening of the inertia phase can be made more reliable.

[0220] Note that the disclosed technology is not limited to the above-described embodiments, and includes various other configurations. For example, the configuration of the automobile 1 is illustrative and can be changed according to the specifications.

[0221] Also, in the above-described improved shift control, the slight slip control is continued even after the period of the pre-charge & hold phase, but the torque phase is controlled as before, and the slight slip control may be independently executed during the period of the pre-charge & hold phase and the period of the inertia phase (front-stage slight slip control and rear-stage slight slip control).

[0222] If so, it is not necessary to superimpose the slight slip control on the switching control of the transmission torque during the torque phase. Therefore, the stability of the control can be ensured as before.

[0223] FIG. 18 illustrates an improved shift control (second improved shift control) when the slight slip control is individually executed. Most of the second improved shift control is the same as the above-described improved shift control, and the same steps are denoted by the same reference numerals and the description thereof is omitted.

[0224] In the second improved shift control, when shifting to the torque phase, the micro slip control (front-stage micro slip control) started during the pre-charge & hold phase is terminated (step S95). Then, during the torque phase, the same control as during normal shifting is executed.

[0225] That is, during the torque phase, the input torques of the first clutch and the second clutch are held by torque control. Then, by gradually decreasing the hydraulic pressure of the first clutch and performing hydraulic pressure feedback control on the second clutch, the torque transmission is switched from the first clutch to the second clutch while keeping the magnitude of the transmitted torque constant.

[0226] If the magnetic force shift control is not executed after the torque phase ends, the process shifts to the inertia phase during normal shifting (step S96).

[0227] On the other hand, if the magnetic force shift control is executed, the process shifts to the inertia phase with magnetic force shift control (step S97). That is, the same control as during the magnetic force shift control during shifting is executed. Specifically, the series of processes shown in FIG. 15 are executed.

Explanation of Signs

[0228] 1 Automobile (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 section 21b Magnetization control section 22 Transmission control unit (TCU) 22a Relay clutch control section 22b Transmission clutch control section 23 Brake Control Unit (BCU) 24 General Control Unit (GCU) 31 Motor Case 32 Shaft 33 Rotor 34 Stator 35 Magnet (Magnetic 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 control device for an electric vehicle comprising a drive motor in which the magnetic poles of a rotor are configured by a magnet with variable magnetic force 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 capable of traveling using electric power, a shift-time magnetic force change control for changing the magnetic force of the variable magnetic force magnet during a shift period of the automatic transmission, a micro-slip control for causing any one of the clutches to perform a rotational speed feedback control based on a differential rotational speed between an input side and an output side of the clutch and to perform a micro-slip at a predetermined rotational speed, is executable, wherein the automatic transmission has a pre-charge & hold phase for adjusting the hydraulic pressure of the first clutch and the second clutch so that the engagement torque of each of a predetermined first clutch before shifting and a predetermined second clutch after shifting is held in the vicinity of the transmission torque, a torque phase for switching the transmission of torque from the first clutch to the second clutch following the pre-charge & hold phase, an inertia phase for switching to a rotational speed corresponding to a gear ratio from the first clutch to the second clutch following the torque phase, has a shift period consisting of, A control device for an electric vehicle that causes the first clutch to perform a micro-slip by performing the micro-slip control during a period of the pre-charge & hold phase.

2. In the control device for an electric vehicle according to Claim 1, A control device for an electric vehicle that performs the magnetic force change control during a period of the inertia phase.

3. In the control device for an electric vehicle according to Claim 2, During traveling of the electric vehicle, in addition to torque control for controlling the motor torque output by the drive motor so as to match a required torque required at the drive wheel, a clutch full engagement 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 performing the magnetic force change control outside the shift period of the automatic transmission, instead of the clutch full engagement control, the clutch is put in a slipped state by lowering the engagement torque to the vicinity of the transmission torque, and after performing the micro-slip control in that state, the magnetic force change control is executed, In the case of the shift-time magnetic force change control, a control device for an electric vehicle that executes the magnetic force change control using a state in which the second clutch is performing a micro-slip.

4. In the control device for an electric vehicle according to claim 2 or 3, A control device for an electric vehicle that executes the magnetic force change control at a timing immediately after shifting from the torque phase to the inertia phase.

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