Electric vehicle control device

Abstract

To suppress a torque variation which occurs along with a magnetism change in a drive motor, without being influenced by the performance of a clutch.SOLUTION: A clutch 83 is disposed between a drive motor 3 and driving wheels 4R, in which the drive motor comprises magnetic poles of a rotor 33 comprised of variable magnetism magnets 35. When an electric vehicle 1 travels, a control device performs a torque control, and a first clutch control in which an engaging torque of the clutch 83 is controlled to be higher than a demanded torque. When performing a magnetization control when the electric vehicle 1 travels, the control device changes the clutch control from the first clutch control to a second clutch control in which the engaging torque is made to coincide with the demanded torque, before the execution of the magnetization control, and adds a given slip torque to the demanded torque to start a micro slip control in which the clutch 83 is brought into a micro slip state from an engaged state.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The disclosed technology relates to a control device for an electric vehicle, such as an electric vehicle or a hybrid vehicle, that can run using electric power. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle equipped with a permanent magnet synchronous drive motor. The drive motor uses a variable magnetic force magnet, whose magnetic force can be varied, as the permanent magnet installed in the rotor.

[0003] The output range of the drive motor is divided into a plurality of magnetized regions, each of which is set to an optimum magnetic force value (optimum magnetic force value).When the output of the drive motor transitions between these magnetized regions, the magnetic force of the variable magnetic force magnet is changed to the optimum magnetic force value at the transition destination. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-027615 Summary of the Invention [Problem to be solved by the invention]

[0005] When changing the magnetic force of a variable magnetic force magnet, a large current (known as d-axis current) is applied to the coil of the drive motor's stator for magnetization. This interferes with the drive current (known as q-axis current), causing torque fluctuations. In other words, the d-axis current is a component that is orthogonal to the q-axis current that generates torque. Therefore, although this large current itself is not output as torque, it interferes with the q-axis current, causing torque fluctuations.

[0006] If the change in magnetic force is a demagnetization, the torque fluctuates in the direction of decreasing, but if the change in magnetic force is an increase, the torque fluctuates in the direction of increasing. Therefore, when the magnetic force of the variable magnetic force magnet is changed in the direction of increasing magnetization, a high torque is output from the drive motor. Generally, the engagement torque of the clutch provided between the drive motor and the drive wheels is higher than the required torque, so when that torque is transmitted to the drive wheels, a torque shock occurs in the vehicle while it is moving, which can cause discomfort to the driver.

[0007] One way to suppress such torque shock is to slip the clutch installed between the drive motor and the drive wheels. In other words, even if a high torque is output from the drive motor, slipping the clutch reduces the torque transmitted to the drive wheels, thereby mitigating the torque shock.

[0008] However, when the clutch is slipped, the rotation of the drive motor suddenly increases (a phenomenon known as "revving up"). If this revving up phenomenon is not resolved quickly, there is a risk that the clutch may be damaged by the frictional heat caused by the slippage.

[0009] Therefore, the present inventors have previously proposed a technology to quickly eliminate the acceleration of the drive motor caused by such clutch slippage (Patent Application No. 2021-95825).

[0010] This technology basically switches from torque control, which targets the torque required for output, to power control, which targets the output power, when slippage occurs in the clutch due to magnetization. This makes it possible to converge the rotation speed as well as the output torque, quickly eliminating the risk of the drive motor racing.

[0011] (Difference in clutch friction coefficient) Generally, the dynamic friction coefficient (μd) of a clutch is set to be equal to the static friction coefficient (μs). Therefore, even if the friction coefficient changes when the clutch is engaged, there is almost no torque shock. Therefore, there is no problem with the technology proposed above.

[0012] However, depending on the clutch, the dynamic friction coefficient may be lower than the static friction coefficient, and the difference between the two may be large. In such cases, even with the technology proposed above, there is a concern that torque shock may occur due to the difference in friction coefficients when the clutch is engaged, causing discomfort to the driver.

[0013] The technology disclosed here suppresses torque fluctuations that occur when the magnetic force of the drive motor is changed, without being affected by the performance of the clutch. [Means for solving the problem]

[0014] The disclosed technology relates to a control device for an electric vehicle that is capable of running using electric power and is equipped with a drive motor whose rotor poles are composed of variable magnetic force magnets whose magnetic force can be changed, and a clutch arranged between the drive motor and the drive wheels.

[0015] When the electric vehicle is traveling, the control device performs torque control to control the motor torque output by the drive motor so that the output matches the required torque required for the drive wheels, and also performs first clutch control to control the engagement torque of the clutch to be higher than the required torque.

[0016] When magnetization control is executed to change the magnetic force of the magnetic force-variable magnet in a magnetization increasing direction while the electric vehicle is running, the first clutch control is changed to second clutch control to match the engagement torque with the required torque before the magnetization control is executed, and micro slip control is initiated to change the clutch from an engaged state to a slight slip state by adding a predetermined slip torque to the required torque based on the dynamic friction coefficient and static friction coefficient of the clutch.

[0017] That is, according to this control device, similar to the previously proposed technology, when magnetization control is executed while the electric vehicle is running, first clutch control is changed to second clutch control, which matches the engagement torque with the required torque, before executing magnetization control. Therefore, torque shock caused by clutch slip and magnetization can be suppressed.

[0018] Furthermore, micro-slip control is initiated to bring the clutch from an engaged state into a slight slip state by adding a predetermined slip torque to the required torque based on the dynamic friction coefficient and static friction coefficient of the clutch.

[0019] That is, rather than switching the clutch from an engaged state to a disengaged state at the timing of the magnetization control when the differential rotation speed of the clutch suddenly increases, a predetermined slip torque is added to the required torque before that, thereby switching the clutch from an engaged state to a slight slip state. This makes it possible to switch the friction coefficient from a static friction coefficient to a kinetic friction coefficient in advance under conditions where the differential rotation speed is small, thereby suppressing torque shock caused by the difference in friction coefficient.

[0020] Therefore, this control device can suppress torque fluctuations that occur due to changes in the magnetic force of the drive motor, without being affected by the performance of the clutch.

[0021] At the start of the micro slip control, transition control may be executed to adjust the hydraulic pressure of the clutch so as to offset a torque change that occurs as the clutch state changes from the engaged state to the slight slip state.

[0022] When micro slip control begins, the clutch changes from an engaged state to a slight slip state. This state change causes a torque change due to the difference in the friction coefficient of the clutch, although it is smaller than the change in the state at the timing of the magnetization control.

[0023] Unlike magnetization control, which outputs irregular torque and is difficult to determine in advance, the slip torque that is increased or decreased in micro-slip control is preset. The torque change that occurs when the friction coefficient changes at the start of micro-slip control is determined by that slip torque, so even hydraulic control, which has poor responsiveness, can be adjusted in response to the torque change.

[0024] Therefore, if hydraulic control conditions are set that can offset this torque change and the clutch hydraulic pressure (pressing force) is adjusted based on these conditions, it is possible to suppress even the slight torque shock that occurs when micro slip control begins.

[0025] During execution of the micro-slip control, instead of the torque control, power control may be executed to control the motor torque so that the power output from the drive wheels coincides with a predetermined target power value.

[0026] Unlike torque control, which simply makes the rotation speed follow the torque, power control allows for well-balanced adjustment of both the rotation speed and torque. Therefore, during execution of micro-slip control, both the torque and rotation speed of the drive motor can be adjusted in a well-balanced manner, allowing for stable convergence to a slight slip state.

[0027] After the magnetization control is performed, feedback control may be performed based on the difference between the rotation speed of the input side and the rotation speed of the output side of the clutch, thereby converging to the slight slip state while the power control is being performed.

[0028] This allows the vehicle to quickly converge to a slight slip state.

[0029] At the end of the micro slip control, transition control may be executed to adjust the hydraulic pressure of the clutch so as to cancel out a torque change that occurs as the clutch state changes from the slight slip state to the engaged state.

[0030] This will also suppress the slight torque shock that occurs when micro-slip control ends, making it possible to change the magnetic force of the drive motor in a nearly shock-free manner. [Effects of the Invention]

[0031] According to the disclosed technology, it is possible to suppress torque fluctuations that occur due to changes in the magnetic force of the drive motor, without being affected by the performance of the clutch. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic diagram showing the main configuration of a vehicle to which the disclosed technology is applied. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a drive motor. [Figure 3] FIG. 2 is a block diagram showing an MCU and its associated main input / output devices. [Figure 4] FIG. 4 is a diagram illustrating an example of an output range of a drive motor. [Figure 5] FIG. 2 is a simplified system diagram relating to control of a drive motor. [Figure 6] 10 is a flowchart illustrating an example of control of a drive motor. [Figure 7] 10 is a flowchart showing the flow of main processing of magnetic force change control. [Figure 8] FIG. 10 is a diagram for explaining the occurrence of torque shock. [Figure 9] FIG. 2 is a block diagram showing the TCU and its associated main input / output devices. [Figure 10] FIG. 1 is a diagram for explaining the blow-up phenomenon. [Figure 11] FIG. 10 is a diagram for explaining the problem of a difference in friction coefficient of a transmission clutch. [Figure 12] 10 is a time chart of main specifications before and after magnetization control to which the disclosed technology is applied. [Figure 13] 13 is a flowchart showing an example of control corresponding to FIG. 12. [Figure 14]14 is a flowchart continuing from FIG. 13. DETAILED DESCRIPTION OF THE INVENTION

[0033] The disclosed technology will be described below, however, the following description is merely exemplary in nature.

[0034] <Electric vehicles> FIG. 1 shows an automobile 1 (an example of an electric vehicle) to which the disclosed technology is applied. The automobile 1 is a hybrid vehicle that can run on electric power. The automobile 1 is equipped with an engine 2 and a drive motor 3 as its drive sources. These work together to drive two wheels (drive wheels 4R) that are positioned symmetrically on the left and right of the four wheels 4F, 4F, 4R, 4R. This allows the automobile 1 to move. Note that the automobile 1 may also be an electric vehicle equipped with only the drive motor 3. The automobile 1 may also be a four-wheel drive vehicle.

[0035] In the case of this automobile 1, the engine 2 is located at the front of the vehicle body, and the drive wheels 4R are located at the rear of the vehicle body. In other words, this automobile 1 is a so-called FR vehicle. Furthermore, in the case of this automobile 1, the engine 2 is the main driving source rather than the drive motor 3, and the drive motor 3 is used to assist the driving of the engine 2 (a so-called mild hybrid). The drive motor 3 is used not only as a driving source, but also as a generator during regeneration.

[0036] In addition to an engine 2 and a drive motor 3, the automobile 1 is equipped with drive system devices such as an intermediate clutch 5, an inverter 6, a transmission 8, a differential gear 9, and a battery 10. The automobile 1 is also equipped with control system devices such as an engine control unit (ECU) 20, a motor control unit (MCU) 21, a transmission control unit (TCU) 22, a brake control unit (BCU) 23, and a general control unit (GCU) 24. 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, and the like are also installed in the automobile 1 as part of the control system devices.

[0037] (Drive system device) The engine 2 is an internal combustion engine that burns gasoline as fuel, for example. The engine 2 is also a so-called four-stroke engine that generates rotational power by repeating cycles of intake, compression, expansion, and exhaust. There are various types and forms of engine 2, such as diesel engines, but the technology disclosed herein is not particularly limited to the type or form of the engine.

[0038] In this automobile 1, the engine 2 is disposed in approximately the center in the width direction of the vehicle, with the output shaft that outputs rotational power facing the front-to-rear direction of the vehicle body. The automobile 1 is equipped with various devices and mechanisms associated with the engine 2, such as an intake system, an exhaust system, and a fuel supply system, but these are not shown or described in the drawings.

[0039] The drive motor 3 is disposed in series behind the engine 2 via an intermediate clutch 5. The drive motor 3 is a permanent magnet synchronous motor driven by three-phase AC. As shown in simplified form in Figure 2, the drive motor 3 is mainly composed of a motor case 31, a shaft 32, a rotor 33, a stator 34, etc.

[0040] Motor case 31 is a container having a cylindrical space therein with its front and rear end faces sealed, and is fixed to the body of automobile 1. Rotor 33 and stator 34 are housed in motor case 31. Shaft 32 is rotatably supported by motor case 31 with its front and rear ends protruding from motor case 31.

[0041] An intermediate clutch 5 is provided so as to be interposed between the front end of the shaft 32 and the output shaft of the engine 2. The intermediate clutch 5 is configured to be switchable between a state in which the output shaft of the engine 2 and the shaft 32 are connected (engaged state) and a state in which the output shaft of the engine 2 and the shaft 32 are separated (disengaged state).

[0042] The rear end of the shaft 32 is connected to an input shaft 80 of the transmission 8. A second relay clutch may be provided between the shaft 32 and the input shaft 80 of the transmission 8.

[0043] The rotor 33 is a cylindrical member made by laminating multiple metal plates each having a central axial hole. The rotor 33 is integrated with the shaft 32 by fixing the middle part of the shaft 32 to the axial hole of the rotor 33.

[0044] Magnets 35 are installed around the entire outer periphery of rotor 33. Magnets 35 are configured so that different magnetic poles, i.e., south poles and north poles, are arranged alternately at equal intervals in the circumferential direction. Magnet 35 may be configured as a single cylindrical magnet having multiple magnetic poles, or may be configured as multiple arc-shaped magnets that form each magnetic pole.

[0045] Furthermore, in this drive motor 3, the magnet 35 is configured so that the magnitude of its magnetic force can be changed (variable magnetic force magnet 35). Typically, this type of drive motor 3 uses a magnet (permanent magnet) that has a large coercive force (resistance) and can maintain its magnetic force for a long period of time. In this drive motor 3, a permanent magnet with a small coercive force is used as the variable magnetic force magnet 35 so that the magnetic force can be changed relatively easily.

[0046] There are various types of permanent magnets, such as ferrite magnets, neodymium magnets, samarium-cobalt magnets, and alnico magnets, and they all have different holding forces. The type and material of the variable magnetic force magnet 35 can be selected according to the specifications and is not particularly limited.

[0047] A cylindrical stator 34 (inner rotor type) is installed around the rotor 33 with a small gap between them. The stator 34 has a stator core 34a formed by laminating multiple metal plates, and multiple coils 36 formed by winding electric wires around the stator core 34a.

[0048] The stator core 34a is provided with a plurality of teeth 34b that radiate inward, and a plurality of coils 36 are formed by winding electric wires around these teeth 34b in a predetermined order. These coils 36 constitute a three-phase coil group consisting of U-phase, V-phase, and W-phase.

[0049] To energize the coil groups of each phase, connection cables 36a are led 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 on the vehicle as a drive power source via an inverter 6. In the case of this automobile 1, the battery 10 is a DC battery with a rated voltage of 50V or less, specifically 48V.

[0050] The battery 10 supplies DC power to the inverter 6. The inverter 6 converts the DC power into three-phase AC and supplies it to the drive motor 3. This rotates the rotor 33, and the power (rotational motive power) of the drive motor 3 is output to the transmission 8 via the shaft 32.

[0051] In the case of this automobile 1, the transmission 8 is a multi-stage automatic transmission (so-called AT). As shown in Fig. 1, the transmission 8 has an input shaft 80 at one end, which is connected to the drive motor 3 (shaft 32). The other end of the transmission 8 has an output shaft 81 which rotates independently from the input shaft 80. A transmission mechanism including a torque converter 84, a plurality of planetary gear mechanisms 82, and a plurality of transmission clutches 83 (including brakes) is incorporated between the input shaft 80 and the output shaft 81.

[0052] By switching these transmission mechanisms, it is possible to switch between forward and reverse, and to change the rotation speed between the input shaft 80 and the output shaft 81 of the transmission 8 to a different value, i.e., to switch the gear ratio.

[0053] For example, an input side 83a of each transmission clutch 83 is configured to be connectable to an input shaft 80 via a torque converter 84. An output side 83b of each transmission clutch 83 is connected to an output shaft 81 via a corresponding planetary gear mechanism 82. When a specific transmission clutch 83 is selected and engaged, the input shaft 80 and output shaft 81 of the transmission are connected via that transmission clutch 83 and the corresponding planetary gear mechanism 82. This changes the gear ratio, etc.

[0054] The output shaft 81 is connected to a differential gear 9 via a propeller shaft 11 that extends in the longitudinal direction of the vehicle body and is arranged coaxially with the output shaft 81. A pair of drive shafts 13, 13 that extend in the vehicle width direction and are connected to the left and right drive wheels 4R, 4R are connected to the differential gear 9. The rotational power output through the propeller shaft 11 is distributed by the differential gear 9 and then transmitted to each drive wheel 4R via the pair of drive shafts 13, 13. A brake 14 is attached to each of the wheels 4F, 4F, 4R, 4R to brake their rotation.

[0055] (Control system devices) The automobile 1 is equipped with the above-mentioned units, ECU 20, MCU 21, TCU 22, BCU 23, and GCU 24, to control its running in response to driver operation. Each of these units is composed of hardware such as a processor, memory, and interface, and software such as a database and control programs. Each of these units is connected by, for example, a CAN (Controller Area Network), and is configured to be able to electrically communicate with one another.

[0056] 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 transmission 8. The BCU 23 is a unit that mainly controls the operation of the brake 14. The GCU 24 is electrically connected to the ECU 20, MCU 21, TCU 22, and BCU 23, and is a higher-level unit that comprehensively controls these.

[0057] The "control device" in the disclosed technology is composed of these units. In particular, the MCU 21, which mainly controls the operation of the drive motor 3, and the TCU 22, which mainly controls the operation of the transmission 8, constitute the main components of the control device. These units work together to perform micro-slip control, which will be described later.

[0058] The engine rotation sensor 50 is attached to the engine 2 and detects the rotation speed of the engine 2, and outputs the detected rotation speed to the ECU 20. The motor rotation sensor 51 is attached to the drive motor 3 and detects the rotation speed and rotation position of the drive motor 3, and outputs the detected rotation speed and rotation position to the MCU 21. The current sensor 52 is attached to the connection cable 36a and detects the value of the current flowing through each coil 36, and outputs the detected rotation speed and rotation position to the MCU 21.

[0059] The magnetic force sensor 53 is attached to the drive motor 3, detects the magnetic force of the variable magnetic force magnet 35, and outputs the result to the MCU 21. The accelerator sensor 54 is attached to the accelerator pedal (accelerator pedal 15) that the driver presses when driving the automobile 1, and detects the accelerator opening amount corresponding to the output required to drive the automobile 1, and outputs the result to the ECU 20. The transmission sensor 55 detects the rotation speed and engagement torque of each transmission clutch 83, the rotation speed of the output shaft 81, and the like, and outputs the result to the TCU 22.

[0060] Based on the detection value signals input from these sensors, each unit cooperates to control each device in the drive system, thereby running the automobile 1. For example, when the automobile 1 runs using 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.

[0061] The TCU 22 then controls the intermediate clutch 5 to be in an engaged state, and switches the speed change mechanism of the transmission 8 in accordance with the driving state of the automobile 1. When braking the automobile 1, the BCU 23 controls the brakes 14. When braking by regeneration, the TCU 22 controls the intermediate clutch 5 to be in a disengaged state or a partially engaged state, and engages a predetermined transmission clutch 83 of the transmission 8. The MCU 21 then controls the drive motor 3 to generate electricity and recover the electricity to the battery 10.

[0062] <Drive motor control> The MCU 21 controls the automobile 1 to run using the power output by the drive motor 3, with the drive motor 3 outputting alone or with the output of the engine 2 being assisted as necessary.

[0063] Specifically, the ECU 20 sets the torque to be output by the engine 2 based on the detected values ​​of the accelerator sensor 54, engine revolution sensor 50, etc. Accordingly, the GCU 24 sets the torque demand (demanded torque) for the drive motor 3 within a predetermined output range in accordance with a preset output distribution ratio between the engine 2 and the drive motor 3. The MCU 21 controls the drive motor 3 so that the demanded torque is output.

[0064] Figure 3 shows the MCU 21 and its main associated input / output devices. The MCU 21 has a functional configuration that includes a motor output control unit 21a and a magnetization control unit 21b, which are implemented by hardware and software. The motor output control unit 21a has the function of controlling the drive of the drive motor 3, and controls the drive current flowing through the coil 36 to cause the drive motor 3 to output the required power.

[0065] On the other hand, the magnetization control unit 21b has a function of increasing the power factor of the drive motor 3, and changes the magnetic force of the variable magnetic force magnet 35 by controlling the magnetization current flowing through the coil 36. Specifically, the magnetic force of the variable magnetic force magnet 35 is changed so that the magnetic force of the variable magnetic force magnet 35 substantially matches the electromagnetic force generated in the coil 36 by the drive current.

[0066] The power factor is the ratio of effective power (power actually consumed) to apparent power (power supplied to the drive motor 3). If the power factor is low, a larger current must be passed to obtain the same output, which results in a larger motor. Therefore, by increasing the power factor of the drive motor 3, the drive motor 3 can be made lighter and more compact. Furthermore, a higher power factor also increases the power generation during regeneration.

[0067] (Drive motor output range) 4 illustrates an example of the output range of the drive motor 3. The output range is defined by an upper load limit line that indicates the upper limit of the torque (load) for each rotation speed.

[0068] Specifically, in the low rotation speed range up to a certain rotation speed (r1), the upper limit of torque is maintained at a maximum (T2). In the medium and high rotation speed ranges where the rotation speed is higher than the low rotation speed range, the upper limit of torque gradually decreases until the rotation speed reaches the upper limit (r2).

[0069] Data such as maps and tables that define such output ranges are stored in advance in the MCU 21. The motor output control unit 21a refers to the data to control the drive motor 3 within the output range.

[0070] Furthermore, the output range of the drive motor 3 is divided into a plurality of magnetized regions, and the magnetization control unit 21b is configured to change the magnetic force of the variable magnetic force magnet 35 in accordance with each of these magnetized regions.

[0071] 4, in this embodiment, the output range of the drive motor 3 is divided into four magnetization regions Rm, namely, first to fourth magnetization regions Rm. Specifically, the range is divided into a first magnetization region Rm1 of high load that is biased toward the low rotation side and includes a maximum torque value T2, a second magnetization region Rm2 that extends from the low rotation side to the high rotation side and has a torque peak at medium rotation at a lower load than the first magnetization region Rm1, a third magnetization region Rm3 that has a lower load than the second magnetization region Rm2 and whose torque peak is shifted to the high rotation side, and a fourth magnetization region Rm4 that has a lower load than the third magnetization region Rm3 and includes a torque T1 at which the drive motor 3 runs idle (torque that does not contribute to the running of the automobile 1).

[0072] Each magnetized region Rm is set with an optimal magnetic force value (magnetic force optimum value) that corresponds to the respective output and achieves a high power factor. For example, in the first magnetized region Rm1, the magnetic force of the variable magnetic force magnet 35 in its initial state is set as the magnetic force optimum value (first magnetic force optimum value). In the second magnetized region Rm2, a magnetic force optimum value lower than the first magnetic force optimum value is set (second magnetic force optimum value). Then, in the third magnetized region Rm3, a third magnetic force optimum value lower than the second magnetic force optimum value is set, and in the fourth magnetized region Rm4, a fourth magnetic force optimum value lower than the third magnetic force optimum value is set.

[0073] The magnetization control unit 21b predicts the optimal magnetized region Rm based on the operating state of the automobile 1, and when the magnetized region Rm transitions to another adjacent magnetized region Rm, changes the magnetic force of the variable magnetic force magnet 35 to the optimal magnetic force value corresponding to that magnetized region Rm. For example, when transitioning from the first magnetized region Rm1 to the second magnetized region Rm2, a demagnetization process is executed in the drive motor 3, and the magnetic force of the variable magnetic force magnet 35 is changed from the first optimal magnetic force value to the second optimal magnetic force value.

[0074] Also, for example, when transitioning from the third magnetization region Rm3 to the second magnetization region Rm2, a magnetization process is executed in the drive motor 3, and the magnetic force of the variable magnetic force magnet 35 is changed from the third magnetic force optimum value to the second magnetic force optimum value.

[0075] (Specific example of drive motor control) FIG. 5 shows a simplified system diagram relating to the control of the drive motor 3. FIG. 6 shows an example of the control of the drive motor 3 performed by the MCU 21. With reference to these figures, the specific flow of control of the drive motor 3 will be described. The drive motor 3 is driven by a torque current command Iq * and excitation current command Id * It is controlled by vector control using

[0076] When the automobile 1 is in a state where it can run, the MCU 21 starts to constantly receive detection values ​​from the current sensor 52, the motor rotation sensor 51, and the magnetic sensor 53 (step S1). Similarly, the ECU 20 also starts to constantly receive detection values ​​from the accelerator sensor 54 and the engine rotation sensor 50.

[0077] The GCU 24 acquires the detection value of the accelerator sensor 54 from the ECU 20, and sets the torque (required torque) required of the drive motor 3 out of the torque output to the drive wheels 4R in accordance with a preset distribution ratio between the engine 2 and the drive motor 3. The GCU 24 issues a command (torque command value T * ) is output to MCU21.

[0078] That is, the MCU 21 controls the output of the drive motor 3 based on a predetermined target torque (so-called torque control). Through torque control, the torque (motor torque) output by the drive motor 3 is controlled to match the target torque. Therefore, when the above-mentioned command is input while the automobile 1 is traveling, the MCU 21 controls the drive motor 3 using the requested torque as the target torque. Through torque control of the drive motor 3, the automobile 1 travels in accordance with the driver's request.

[0079] Also, as described above, when the automobile 1 is traveling, torque control is interrupted when the magnetized region Rm is shifted, and control is executed to apply a high voltage to the coil 36 of the drive motor 3 (magnetic force change control). The magnetic force of the magnetic force-variable magnet 35 is changed by the magnetic force change control.

[0080] Specifically, the MCU 21 (motor output control unit 21a) calculates the torque command value T * When the answer to step S2 is Yes, a command (drive current command value Idq) is issued to output the amount of change in the drive current (torque current component) that generates the torque. * ) (Step S3). The MCU 21 (magnetization control unit 21b) also issues a command (magnetization state command value Φ * ) (step S4). The magnetization control unit 21b calculates the magnetization state command value Φ * Based on this, a command (magnetic force current command value Idq) that outputs a torque current component corresponding to the amount of change in the magnetic force of the variable magnetic force magnet 35 is generated. * ) is calculated (step S5).

[0081] The MCU 21 calculates the drive current command value Idq * and magnetic current command value Idq *Based on this, it is determined whether or not the magnetic force of the magnetic force variable magnet 35 needs to be changed (step S6). For example, as described above, if the magnetized region Rm transitions to another magnetized region Rm when the requested torque is output, it is determined that the magnetic force of the magnetic force variable magnet 35 needs to be changed, and if the requested torque is output but the magnetized region Rm remains the same, it is determined that the magnetic force of the magnetic force variable magnet 35 does not need to be changed.

[0082] If the MCU 21 determines that it is not necessary to change the magnetic force of the variable magnetic force magnet 35, it determines whether the output torque is greater than the torque T1 at which the drive motor 3 runs idle (step S7). If the output torque is greater than the torque T1, the MCU 21 controls the drive motor 3 by normal vector control.

[0083] That is, the motor output control unit 21a outputs a command (voltage command value Vuvw) to perform PWM control based on the detection values ​​of the current sensor 52 and the motor rotation sensor 51 by current control. * ) is calculated (step S8). Then, a switching command value is calculated by PWM control (step S9).

[0084] The switching command value is output to the inverter 6 via a driver circuit, thereby controlling the on / off of multiple switching elements inside the inverter 6. As a result, a predetermined three-phase AC (drive current) is passed through each coil group, and the drive motor 3 rotates with the required torque (step S10).

[0085] On the other hand, if the MCU 21 determines that the magnetic force of the variable magnetic force magnet 35 needs to be changed (No in step S6), the magnetization control unit 21b executes magnetic force change control (step S11).

[0086] Furthermore, even if the MCU 21 determines that it is not necessary to change the magnetic force of the magnetic force variable magnet 35, if it determines that the output torque is equal to or less than the torque T1 at which the drive motor 3 runs idle (No in step S7), the magnetization control unit 21b executes magnetic force change control (step S11).

[0087] That is, when the required amount of rotational power of the drive motor 3 becomes almost 0 (zero), the magnetic force of the variable magnetic magnet 35 is changed to the initial state (reset). In the case of the automobile 1, for example, there are cases where the accelerator pedal 15 is suddenly depressed from an idling state or a stopped state, causing sudden acceleration.

[0088] In the case of the variable magnetic force magnet 35, the magnetic force in the initial state is set high to match the high load, so by resetting the magnetic force during idle operation, the drive motor 3 can be driven appropriately even when such sudden acceleration is performed.

[0089] 7 shows the flow of the main process of the magnetic force change control. When the magnetic force change control is requested, the magnetization control unit 21b calculates the magnetization state command value Φ * The direction of the magnetization process is determined based on the result of the magnetization control unit 21b. That is, it is determined whether to execute a process to increase the magnetic force of the variable magnetic force magnet 35 (magnetization process) or to execute a process to decrease the magnetic force of the variable magnetic force magnet 35 (demagnetization process). The magnetization control unit 21b further specifies the amount of change in the magnetic force.

[0090] Then, based on the detection value of the motor rotation sensor 51, the magnetization control unit 21b determines whether the position (position in the direction of rotation) of the rotor 33 relative to the stator 34 is appropriate for the magnetization process (step S21), and outputs a magnetization current when the rotor 33 is positioned appropriately (step S22). The magnetization current is a pulsed current that generates an electromagnetic force greater than the coercive force of the variable magnetic force magnet 35. The directions of the magnetic field lines of the electromagnetic force are opposite between the magnetization process and the demagnetization process.

[0091] The magnetization control unit 21b controls the magnetic force of the variable magnetic force magnet 35 to be equal to or greater than the magnetization state command value Φ *(Step S23), and the magnetization process is carried out until the magnetic force of the variable magnetic force magnet 35 becomes approximately the same as the magnetic force optimum value. When resetting the magnetic force of the variable magnetic force magnet 35, the magnetization process is carried out until the magnetic force becomes approximately the same as the initial magnetic force.

[0092] Then, when the magnetic force of the variable magnetic force magnet 35 becomes substantially the same as its optimum magnetic force value or the initial magnetic force, the magnetic force change control is terminated, and the drive motor 3 is controlled by normal vector control as shown in FIG. 6 (steps S8 to S10).

[0093] <Clutch slip> As described above, in this automobile 1, the magnetic force change control is executed even when the automobile 1 is traveling. If the magnetic force change control in the direction of increasing magnetism (magnetization control) is executed while the automobile 1 is traveling, a torque shock may occur in the traveling automobile 1, causing a sense of discomfort to the driver.

[0094] The upper graph in Figure 8 illustrates an example of how the motor torque Tm changes over time during magnetization control. In this example, magnetization processing is performed during the period from time t1 to t1'. The period from t1' to t2 is a period in which changes in magnetic force are confirmed and control (learning control) is performed to learn the drive current value (q-axis current value) so that it corresponds to the magnetic force after magnetization, thereby matching the motor torque Tm to the required torque. The learning control is control associated with magnetization and is included in the magnetization control. Ta is the required torque. Because the drive motor 3 is torque controlled while the automobile 1 is traveling, the motor torque Tm before the magnetization control is performed matches the required torque Ta.

[0095] Tt is the clutch engagement torque in the transmission 8. The clutch engagement torque Tt is the engagement torque of the transmission clutch 83 that connects the input shaft 80 and output shaft 81 of the transmission 8, and corresponds to the torque that the transmission clutch 83 can transmit to its output side 83b. In order to reliably transmit the motor torque Tm to the drive wheels 4R, the clutch engagement torque Tt is normally controlled (first clutch control) to be higher than the required torque Ta.

[0096] During magnetization control, a magnetizing current (d-axis current) is passed through the coil 36 to generate a large electromagnetic force. This causes a high voltage that significantly exceeds the drive voltage to be applied to the drive motor 3. Therefore, as shown in the upper diagram of FIG. 8, during magnetization control, a high peak motor torque Tm that significantly exceeds the required torque Ta is output from the drive motor 3. As a result, a torque shock occurs in the moving vehicle 1, which may cause discomfort to the driver.

[0097] Therefore, in order to suppress such torque shock, in this automobile 1, the MCU 21 cooperates with the TCU 22 to slip the transmission clutch 83 during magnetization control (including the associated learning control). Specifically, control is performed (second clutch control) so that the clutch engagement torque Tt coincides with the required torque Ta.

[0098] FIG. 9 shows the TCU 22 and its associated main input / output devices. The TCU 22 has, as its functional components, an intermediate clutch control unit 22a and a transmission clutch control unit 22b, which are provided by their hardware and software. The intermediate clutch control unit 22a controls the operation of the intermediate clutch 5. The transmission clutch control unit 22b controls the operation of each of the transmission clutches 83. The first clutch control and the second clutch control are executed by the transmission clutch control unit 22b.

[0099] When the transmission clutch control unit 22b acquires information related to the execution of magnetic force change control from the GCU 24, it controls the operation of the transmission clutch 83 in use accordingly. Specifically, as shown in the lower diagram of FIG. 8, the transmission clutch control unit 22b switches from the first clutch control to the second clutch control immediately before the start of the magnetization control (time t1) (time t0). This reduces the clutch engagement torque Tt. As a result, the transmission clutch 83 slips.

[0100] At this time, the clutch engagement torque Tt is controlled to match the required torque. By executing the second clutch control, even if a high motor torque Tm is output from the drive motor 3, torque exceeding the required torque is not transmitted to the drive wheels 4R. As a result, torque shock caused by magnetization can be suppressed.

[0101] <Issues and solutions in second clutch control> When the transmission clutch 83 is caused to slip, a phenomenon occurs in which the rotation of the drive motor 3 increases suddenly (so-called "revving up").

[0102] Fig. 10 shows the relationship between motor torque Tm and motor rotation speed Rm during magnetization control. Note that, since the output of engine 2 is not taken into consideration here, motor rotation speed Rm is also the rotation speed of input shaft 80 of transmission 8. Furthermore, motor torque Tm corresponds to the torque input to transmission 8 (torque on input side 83a of transmission clutch 83: transmission input torque). Clutch engagement torque Tt is controlled to match the required torque, and therefore corresponds to the torque output from transmission 8 (torque on output side 83b of transmission clutch 83: transmission output torque).

[0103] Before the magnetization control is executed, the drive motor 3 rotates at a predetermined rotation speed Ra. At this time, the transmission clutch 83 being used is engaged, so both the input side 83a and the output side 83b of the transmission clutch 83 also rotate at the rotation speed Ra. The output shaft 81 of the transmission 8 rotates at a rotation speed changed by the planetary gear mechanism 82 corresponding to the transmission clutch 83.

[0104] As shown in Figure 10, if transmission clutch 83 is slipped during magnetization control, the drive motor 3 will enter an idle state, causing motor rotation speed Rm to suddenly increase from rotation speed Ra corresponding to the required torque Ta. During learning control, motor rotation speed Rm continues to increase, and remains high. If this racing phenomenon is not resolved quickly, frictional heat caused by slippage may damage transmission clutch 83.

[0105] Furthermore, torque control controls the motor torque Tm to match the target torque (required torque Ta) according to the current rotation speed. Therefore, after the rotation speed increases due to the racing phenomenon, that rotation speed is maintained. In other words, the racing phenomenon cannot be resolved by conventional torque control alone.

[0106] One possible measure to quickly resolve the racing phenomenon is to increase the clutch engagement torque Tt, which was previously set to match the required torque Ta, immediately after the magnetization control is performed. This reduces slippage, which in turn reduces the motor rotation speed Rm, thereby eliminating the racing phenomenon. However, this results in a reactionary high motor torque Tm being transmitted to the drive wheels 4R, which causes a torque shock.

[0107] Another possible solution is to reduce the target torque in torque control to be smaller than the required torque Ta immediately after the magnetization control, thereby reducing the motor torque Tm itself. This reduces the motor rotation speed Rm, thereby eliminating the racing phenomenon.

[0108] However, this may cause the motor rotation speed Rm to drop below the initial rotation speed Ra. In this case, even if the motor torque Tm is restored to the required torque by torque control after the racing phenomenon is resolved, the motor rotation speed Rm will not return to its initial state. This may cause a sense of discomfort to the driver due to insufficient power of the drive motor 3.

[0109] Therefore, in the previously proposed technology, power control is performed to control the motor torque Tm based on the power output from the drive motor 3 after the magnetization control, and it is devised to enable the torque and rotation speed output from the drive motor 3 to converge quickly. However, with this technology, depending on the performance of the transmission clutch 83, there is a possibility that torque shock may occur, causing discomfort to the driver, and it has been found that there is room for improvement.

[0110] <Difference in friction coefficient of transmission clutch> In general, the dynamic friction coefficient (μd) of the transmission clutch 83 is set to be equal to the static friction coefficient (μs).

[0111] When transmission clutch 83 is engaged, the friction coefficient switches from a dynamic friction coefficient to a static friction coefficient. If the dynamic friction coefficient and the static friction coefficient are equivalent, no torque shock occurs that would cause discomfort to the driver when transmission clutch 83 is engaged due to magnetization control. Therefore, there is no problem with the technology proposed above.

[0112] However, depending on the transmission clutch 83, the dynamic friction coefficient may be lower than the static friction coefficient, and the difference may be large. In such cases, even with the technology proposed above, there is a concern that torque shock may occur when the transmission clutch 83 is engaged due to magnetization control, causing discomfort to the driver.

[0113] This point will be explained in detail with reference to Figure 11. The lower diagram in Figure 11 shows the change over time in the differential rotation speed between the input side 83a and the output side 83b of transmission clutch 83, with magnetization control starting at t1. When there is a difference between the dynamic friction coefficient and static friction coefficient of transmission clutch 83, possible torque control methods include control tailored to the dynamic friction coefficient (µd tailored control) and control tailored to the static friction coefficient (µs tailored control).

[0114] The upper graph in FIG. 11 shows μd matching control. The middle graph in FIG. 11 shows μs matching control. In these graphs, the dashed line corresponds to the transmission input torque Tm, and the solid line corresponds to the transmission output torque Tt. In μd matching control, control is performed based on the dynamic friction coefficient (μd), so the target transmission input torque Tm is the value obtained by multiplying the hydraulic pressure (pressing force) acting on the transmission clutch 83 by the dynamic friction coefficient. On the other hand, in μs matching control, control is performed based on the static friction coefficient (μs), so the target transmission input torque Tm is the value obtained by multiplying the hydraulic pressure (pressing force) acting on the transmission clutch 83 by the static friction coefficient.

[0115] In μd matching control, when the transmission clutch 83 begins to slip with the start of magnetization control, the transmission output torque Tt also increases up to its upper limit (the value obtained by multiplying the pressing force by the static friction coefficient) as the differential rotation speed increases. If this fluctuation in the transmission output torque Tt (sudden shock) exceeds the level that a human senses, it may cause the driver to feel uncomfortable.

[0116] Furthermore, in μs matching control, when the transmission clutch 83 begins to slip as the magnetization control begins, the friction coefficient changes and the transmission output torque Tt decreases to a value obtained by multiplying the pressing force by the dynamic friction coefficient. This state is maintained until the magnetization control ends and the transmission clutch 83 is re-engaged. If the fluctuations in the transmission output torque Tt (pull-in shock) during this time exceed the level that a human senses, it may cause the driver to feel uncomfortable.

[0117] In either control, if the difference between the static and dynamic friction coefficients of the transmission clutch 83 is large, torque shock due to the difference in friction coefficients may occur as a result of the magnetization control, which may cause discomfort to the driver.

[0118] It is conceivable to suppress the torque shock by adjusting the pressing force of the transmission clutch 83 when it is engaged using hydraulic control. However, hydraulic control has low responsiveness and cannot respond instantaneously. It is not easy to stably suppress the torque shock that accompanies irregular magnetization control using hydraulic control with low responsiveness.

[0119] Therefore, this control device is devised so that unacceptable torque fluctuations that may occur due to changes in the magnetic force of the drive motor, specifically due to magnetization control, can be suppressed by controlling the transmission clutch 83.

[0120] Specifically, similar to the previously proposed technology, first clutch control is executed together with torque control when the automobile 1 is running. Then, when magnetization control is executed while the automobile 1 is running, the first clutch control is switched to second clutch control before the magnetization control is executed. In other words, by slipping the transmission clutch 83, torque shock caused by magnetization is suppressed.

[0121] This control device then sets a new required torque (slightly increased required torque) by adding a predetermined slip torque to the required torque based on the dynamic friction coefficient and static friction coefficient of transmission clutch 83. Then, together with the change to second clutch control (i.e., before execution of magnetization control), control is started to change transmission clutch 83 from an engaged state to a slight slip state (micro slip control) based on the slightly increased required torque.

[0122] That is, rather than switching transmission clutch 83 from an engaged state to a disengaged state at the timing when the differential rotation speed of transmission clutch 83 increases sharply (when magnetization begins), transmission clutch 83 is switched to a state where it slips slightly (a slight slip state) before that. This makes it possible to switch the friction coefficient from a static friction coefficient to a kinetic friction coefficient in advance under conditions where the differential rotation speed is small, thereby suppressing torque shock caused by the difference in friction coefficient.

[0123] The slight slip state occurs when the transmission clutch 83 is not fully engaged and the friction coefficient has changed from a static friction coefficient to a dynamic friction coefficient. By switching to second clutch control, the clutch engagement torque matches the required torque. Therefore, the slip torque added to the required torque only needs to be sufficient to create the slight slip state.

[0124] During the execution of micro-slip control, it is preferable to execute power control instead of torque control.Furthermore, after the execution of magnetization control, it is more preferable to execute feedback control based on 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, and to converge to a micro-slip state during the execution of power control.

[0125] This allows the rotation speed of the drive motor 3 to be adjusted in a well-balanced manner along with the torque output by the drive motor 3, and the racing phenomenon to be quickly resolved. Therefore, the drive motor 3 can be restored to its original state in a short time after being magnetized.

[0126] <Power control and feedback control with micro-slip control> In the power control, torque control is executed so that the power output from the drive wheel 4R, that is, the product of the torque T and the rotation speed R of the drive wheel 4R, becomes a predetermined target power value (target power value).

[0127] That is, in power control, torque control is executed in which the target torque is not the required torque Ta but the motor torque Tm corresponding to the target power value. If the target power value is constant, when the motor rotation speed Rm is high, such as at the peak of the racing phenomenon, the target torque decreases accordingly, and when the racing phenomenon weakens and the motor rotation speed Rm decreases, the target torque increases. Therefore, unlike torque control, power control can adjust both the rotation speed and torque in a balanced manner.

[0128] The target power value here is a value that puts the transmission clutch 83 into a slight slip state. As a result, while micro slip control is being executed, both the torque and rotation speed of the drive motor 3 can be adjusted in a balanced manner, and the transmission clutch 83 can be stably brought into a slight slip state.

[0129] Specifically, the target power value here is a value obtained by multiplying the slightly increased required torque by the rotation speed. For example, the target power value can be set by multiplying the required torque Ta by the actual rotation speed of the drive motor 3 by a predetermined slip ratio, such as 105%.

[0130] The target power value is the required torque Ta multiplied by the actual rotation speed and a predetermined slip ratio. Therefore, power control is an additional control to torque control and is compatible with torque control. Therefore, these controls can be smoothly and easily switched between each other, resulting in excellent control stability.

[0131] After the magnetization control is executed, the motor torque Tm is reduced by the power control, and the motor rotation speed Rm also decreases. However, at this time, the motor rotation speed Rm changes passively in response to the change in torque. Therefore, the motor rotation speed Rm decreases gradually. Therefore, it takes a relatively long time for the motor rotation speed Rm to converge to the rotation speed in the slight slip state (slight slip rotation speed).

[0132] Therefore, after the magnetization control is performed, feedback control is performed based on the difference (differential rotation speed) between the rotation speed of the input side 83a and the rotation speed of the output side 83b of the transmission clutch 83 being used, and the state is converged to a slight slip state while the power control is being performed.

[0133] When the feedback control is started, the gain of the torque control is adjusted according to the differential rotation speed so that the slight slip state is quickly achieved, thereby allowing the transmission clutch 83 to quickly converge to the initial slight slip state.

[0134] <Transition control> Furthermore, it is preferable to perform cooperative control using hydraulic control at the start and / or end of micro slip control. Specifically, control (transition control) is performed to adjust the hydraulic pressure of transmission clutch 83 together with torque adjustment so that torque changes (torque shock) that occur due to state changes in transmission clutch 83 before and after micro slip control are offset.

[0135] For example, when micro-slip control starts, the transmission clutch 83 changes from an engaged state to a slight slip state. When micro-slip control ends, the transmission clutch 83 changes from a slight slip state to an engaged state. These state changes of the transmission clutch 83 cause torque changes due to differences in the friction coefficient of the transmission clutch 83.

[0136] Unlike magnetization control, which outputs irregular torque that is difficult to determine in advance, the slip torque increased or decreased by micro-slip control is a preset value. The torque change that occurs when the friction coefficient changes at the start or end of micro-slip control is determined by the slip torque, so even hydraulic control, which has poor responsiveness, can be adjusted in response to the torque change.

[0137] For example, hydraulic control conditions that can offset torque changes caused by increases or decreases in slip torque are established through preliminary testing, and the hydraulic pressure (pressing force) of the transmission clutch 83 is adjusted based on these conditions. This makes it possible to suppress minute torque shocks caused by differences in the friction coefficient that occur with micro-slip control. As a result, the magnetic force of the drive motor 3 can be changed in an almost shock-free manner.

[0138] <Specific control examples> Specific examples of micro-slip control are shown in Figures 12, 13, and 14. Figure 12 is a time chart of the main parameters before and after magnetization control. Figures 13 and 14 are flowcharts of the control performed by the control device, corresponding to Figure 12.

[0139] 12, the upper part is a time chart relating to torque. The solid line represents the transmission input torque (motor torque Tm), and the dashed line represents the transmission output torque.

[0140] The middle part is a time chart relating to the hydraulic pressure of the transmission 8 (the pressing force of the transmission clutch 83). The bottom part is a time chart relating to the differential rotation speed. It shows 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 being used.

[0141] 13, the MCU 21 determines whether or not magnetization control is to be executed (step S30). If it is determined that magnetization control is to be executed, the TCU 22 changes from first clutch control to second clutch control (step S31). As a result, the clutch engagement torque Tt becomes equal to the required torque Ta.

[0142] The TCU 22 also starts adjusting the hydraulic pressure in accordance with the transition control that is executed thereafter (step S32). Specifically, the hydraulic pressure supplied to the transmission 8 is reduced in advance to a predetermined set hydraulic pressure Pt that has been set in advance.

[0143] Then, when the hydraulic pressure reaches the set hydraulic pressure Pt (t0 in FIG. 12), the MCU 21 interrupts the torque control and starts torque adjustment for transition control (step S33). That is, the required torque Ta is changed to the slightly increased required torque Ta' by adding slip torque so that the transmission clutch 83 in use transitions from an engaged state to a slight slip state.

[0144] As a result, transmission clutch 83 begins to slip slightly, and the differential rotation speed increases (t0 to t1 in FIG. 12). The friction coefficient switches from a static friction coefficient to a dynamic friction coefficient, and the transmission output torque decreases accordingly. Note that this control example shows a case where the torque control is performed using the μs matching control described above.

[0145] The TCU 22 increases the hydraulic pressure in accordance with the decrease in transmission output torque so as to offset the decrease in transmission output torque (t0 to t2 in FIG. 12). This suppresses the torque shock caused by the difference in friction coefficients and keeps the torque change at a level that is imperceptible to humans. Therefore, the transmission clutch 83 can be switched from the engaged state to the slight slip state without causing any discomfort to the driver.

[0146] When the differential rotation speed reaches the rotation speed Rs (slight slip rotation speed) corresponding to the slight slip state (t1 in FIG. 12), the MCU 21 starts power control aimed at the slight slip state (step S34). As a result, the transmission clutch 83 converges to the slight slip state and maintains that state. The transmission input torque stabilizes at the slightly increased required torque Ta', and the differential rotation speed stabilizes at the slight slip rotation speed Rs (after t2 in FIG. 12). Similarly, the oil pressure stabilizes at a predetermined oil pressure.

[0147] When the transmission clutch 83 enters a slight slip state, the MCU 21 starts magnetization control (step S35). The period from time t3 to t4 in FIG. 12 corresponds to magnetization control (including learning control). During this period, as described above, a high motor torque Tm is output from the drive motor 33. Accordingly, the motor rotation speed Rm increases, and the differential rotation speed also increases (revving phenomenon).

[0148] In contrast, the second clutch control causes the clutch engagement torque Tt to match the required torque Ta. As a result, even if a high motor torque Tm is output by the magnetization control, a transmission output torque substantially equal to the required torque Ta is output downstream of the transmission clutch 83. Therefore, torque shock caused by magnetization can be suppressed.

[0149] When the magnetizing control ends (Yes in step S36), the transmission input torque decreases. During this time, power control is still being executed. In power control, torque control is executed using a target torque corresponding to a target power value, as described above. Therefore, with the end of the magnetizing control, the increased transmission input torque decreases, and the differential rotation speed also decreases.

[0150] However, the differential rotation speed at this time decreases gradually. Therefore, it takes a relatively long time for it to converge to the slight slip rotation speed Rs. Therefore, the MCU 21 cooperates with the TCU 22 (transmission clutch control unit 22b) to start feedback control during the execution of power control.

[0151] 14, when the differential rotation speed becomes less than the reference value Rf (Yes in step S37), feedback control is started (step S38). The reference value Rf is set in the TCU 22 in accordance with the specifications of the transmission 8.

[0152] The TCU 22 compares the differential rotation speed, which is actually measured or estimated based on the detection value of the transmission sensor 55, with its reference value Rf. If the TCU 22 determines that the differential rotation speed is less than the reference value Rf (t5 in FIG. 12), it starts feedback control of the rotation speed of the transmission clutch 83 so that the differential rotation speed converges to a slight slip state, that is, so that the differential rotation speed becomes the slight slip rotation speed Rs. By executing the feedback control, the transmission clutch 83 can be quickly returned to the slight slip state.

[0153] Then, when the differential rotation speed reaches the slight slip rotation speed Rs (Yes in step S39), that is, when the transmission clutch 83 returns to the slight slip state, the power control and feedback control are ended and transition control is started (step S40, t6 in FIG. 12).

[0154] That is, the MCU 21 changes the slightly increased required torque Ta' to the required torque Ta by removing the slip torque so that the transmission clutch 83 goes from the slight slip state to the engaged state.

[0155] As a result, the differential rotation speed decreases (t6 to t7 in FIG. 12). When transmission clutch 83 is engaged, the coefficient of friction switches from a dynamic coefficient of friction to a static coefficient of friction, and as a result, the transmission output torque increases.

[0156] The TCU 22 reduces the hydraulic pressure in accordance with the increase in transmission output torque so as to offset the increase in transmission output torque. This suppresses the torque shock caused by the difference in friction coefficients and keeps the torque change at a level that is imperceptible to humans. Therefore, the transmission clutch 83 can be switched from the slight slip state to the engaged state without causing any discomfort to the driver.

[0157] Through this series of steps, the racing phenomenon is resolved, and the motor torque Tm and motor rotation speed Rm are restored to their initial states. The transmission clutch 83 is also restored to the engaged state (t7 in FIG. 12). As a result, the MCU 21 resumes torque control (step S41).

[0158] The TCU 22 changes from second clutch control to first clutch control (step S42). As a result, the clutch engagement torque Tt increases to a normal value (after t7 in FIG. 12). The TCU 22 also increases the hydraulic pressure supplied to the transmission 8 to a normal value. As a result, the drive motor 3 and the transmission 8 return to the states before the magnetization control.

[0159] In this way, with a control device incorporating the disclosed technology, even if magnetization control is performed to generate a motor torque Tm higher than the required torque while the vehicle 1 is running, the torque shock caused by magnetization can be suppressed by second clutch control. Furthermore, the racing phenomenon of the drive motor 33 that occurs when the transmission clutch 83 slips can be quickly resolved by power control and feedback control, allowing for a smooth return to an appropriate control state.

[0160] Furthermore, micro-slip control can also suppress torque shock caused by differences in the friction coefficient of transmission clutch 83. Therefore, even if there is a large difference between the dynamic friction coefficient and static friction coefficient of transmission clutch 83, there is no concern that the driver will feel uncomfortable.

[0161] This control device can suppress torque fluctuations that occur due to changes in the magnetic force of the drive motor 3, regardless of the performance of the transmission clutch 83. This expands the range of application of the transmission clutch 83, making it highly convenient.

[0162] The disclosed technology is not limited to the above-described embodiment, but also includes various other configurations. For example, there are many different configurations for the drive motor 3, the transmission 8, etc. The same is true for the automobile 1. Therefore, these configurations can be selected according to the specifications, and the disclosed technology can be applied according to the specifications. [Explanation of symbols]

[0163] 1. Automobiles (electric vehicles) 2 engines 3 Drive motor 3 4R drive wheel 5 Intermediate clutch 8-speed 10 Battery 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 Intermediate clutch control unit 22b Transmission clutch control unit 23 Brake Control Unit (BCU) 24 General Control Unit (GCU) 33 Rotor 34 Stator 35 Magnet (variable magnetic force magnet) 80 input shaft 81 Output shaft 82 Planetary gear mechanism 83 Transmission clutch 83a Input side 83b Output side

Claims

1. A control device for an electric vehicle that is capable of running using electric power and that is equipped with a drive motor having a rotor whose magnetic poles are configured with variable magnetic force magnets whose magnetic force can be changed, and a clutch that is arranged between the drive motor and a drive wheel, When the electric vehicle is traveling, torque control is performed to control the motor torque output by the drive motor so that the output coincides with a required torque required for the drive wheels, and first clutch control is performed to control the engagement torque of the clutch to be higher than the required torque, when executing magnetization control for changing the magnetic force of the magnetic force variable magnet in a magnetization increasing direction while the electric vehicle is traveling, before executing the magnetization control, the first clutch control is changed to second clutch control for matching the engagement torque with the required torque, and a micro slip control is started for changing the clutch from an engaged state to a slight slip state by adding a predetermined slip torque to the required torque based on the dynamic friction coefficient and static friction coefficient of the clutch; A control device wherein, during execution of the micro-slip control, instead of the torque control, power control is executed to control the motor torque so that the power output from the drive wheels coincides with a predetermined target power value.

2. 2. The control device according to claim 1, a control device that, at the start of the micro slip control, executes transition control that adjusts hydraulic pressure of the clutch so as to cancel out a torque change that occurs as the clutch state changes from the engaged state to the slight slip state.

3. 3. The control device according to claim 1, a control device that, after the magnetization control is performed, performs feedback control based on the difference between the rotation speed of the input side and the rotation speed of the output side of the clutch, thereby causing the clutch to converge to the slight slip state while the power control is being performed.

4. 4. The control device according to claim 3, a control device that, when the micro slip control is terminated, executes transition control to adjust the hydraulic pressure of the clutch so as to cancel out a torque change that occurs as the clutch state changes from the slight slip state to the engaged state.

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