Electrified vehicle

Abstract

To prevent a rotational position sensor from failing to appropriately perform origin point learning.SOLUTION: An electrified vehicle comprises a traveling motor, a rotational position sensor which detects a rotational position of the motor, and a control device which controls the motor based on the rotational position detected with the rotational position sensor and executes turning time control controlling the motor in a manner that prevents a change in a pitch angle from delaying with respect to a change in a roll angle while a vehicle is turning. The control device prohibits execution of the turning time control while the rotational position sensor executes origin point learning.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to electric vehicles. [Background technology]

[0002] Conventionally, in a vehicle equipped with a prime mover that applies power to the left and right drive wheels, a system has been proposed in which, when steering such that the steering angle deviates from the center position, a correction amount of driving force for controlling the vehicle's yaw rate to a target yaw rate is superimposed on a command value for the driving force for the prime mover, and the prime mover is controlled based on the command value after superimposition (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-133811 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric vehicle equipped with a driving motor and a rotational position sensor that detects the rotational position of the motor, if turning control is executed to control the motor during origin learning of the rotational position sensor so as to suppress a delay in pitch change in response to roll change during turning, the influence of the turning control may interfere with the origin learning of the rotational position sensor, making it possible that origin learning cannot be performed properly.

[0005] The main object of the electric vehicle of the present disclosure is to prevent the origin learning of the rotational position sensor from being unable to be performed appropriately. [Means for solving the problem]

[0006] The electric vehicle of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The electric vehicle disclosed herein is An electric vehicle including a motor for driving, a rotational position sensor for detecting a rotational position of the motor, and a control device for executing turning control that controls the motor based on the rotational position detected by the rotational position sensor and controls the motor so as to suppress a delay in a change in pitch angle relative to a change in roll angle when the vehicle is turning, The control device prohibits the execution of the turning control when the origin learning of the rotation position sensor is executed. The gist of the present invention is as follows.

[0008] In the electric vehicle disclosed herein, when the origin learning of the rotational position sensor is being performed, the execution of the turning control is prohibited. This makes it possible to prevent the influence of the turning control from interfering with the origin learning. As a result, it is possible to prevent the origin learning of the rotational position sensor from being unable to be performed appropriately. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an electric vehicle 20 according to an embodiment of the present invention. [Diagram 2] 11 is an explanatory diagram showing d-axis and q-axis voltages Vd, Vq in cases where the rotational position sensor 32a does not include an offset error and in cases where the rotational position sensor 32a includes an offset error. FIG. [Diagram 3] 4 is a flowchart showing an example of a processing routine executed by an ECU 50. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of an electric vehicle 20 according to the present embodiment. As shown in the figure, the electric vehicle 20 according to the present embodiment includes a motor 32, an inverter 34, a battery 36, and an electronic control unit (hereinafter referred to as "ECU") 50.

[0011] The motor 32 is configured as a synchronous generator motor, and includes a rotor with a permanent magnet embedded in the rotor core, and a stator with a three-phase coil wound around the stator core. The rotor of the motor 32 is connected to a drive shaft 26 that is connected to the drive wheels 22a, 22b via a differential gear 24.

[0012] The inverter 34 is used to drive the motor 32 and is connected to the power line 38 together with the battery 36. The inverter 34 includes six transistors T11-T16 as switching elements and six diodes D11-D16 connected in parallel to the six transistors T11-T16, respectively. The transistors T11-T16 are arranged in pairs, two at a time, so as to be on the source side and the sink side of the positive and negative lines of the power line 38, respectively. Each of the connection points of the paired transistors T11-T16 is connected to each of the three-phase (U-phase, V-phase, W-phase) coils of the motor 32. Therefore, when a voltage is applied to the inverter 34, the ECU 50 adjusts the ratio of the on-time of the paired transistors T11-T16, thereby forming a rotating magnetic field in the three-phase coils and driving the motor 32 to rotate.

[0013] The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery having a rated voltage of about several hundred volts, and is connected to the power line 38 together with the inverter 34 as described above.

[0014] The ECU 50 includes a microcomputer, which has a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. The ECU 50 receives signals from various sensors via the input port. For example, the ECU 50 receives a rotational position θm from a rotational position sensor (e.g., a resolver) 32a that detects the rotational position of the rotor of the motor 32, and phase currents Iv and Iw from current sensors 32v and 32w that detect the V-phase and W-phase currents of the motor 32. The ECU 50 also receives a voltage Vb from a voltage sensor 36v attached between the terminals of the battery 36, and a current Ib from a current sensor 36i attached to the output terminal of the battery 36. The ECU 50 also receives a start signal from a start switch 60, a shift position SP from a shift sensor 62 that detects the operation position of a shift lever 61, an accelerator opening Acc from an accelerator sensor 64 that detects the depression amount of an accelerator pedal 63, a brake pedal position from a brake sensor 66 that detects the depression amount of a brake pedal 65, and a vehicle speed V from a vehicle speed sensor 67. The yaw rate ωy from the yaw rate sensor 68, the roll rate ωr from the roll rate sensor 69, and the pitch rate ωp from the pitch rate sensor 70 are also input.

[0015] The ECU 50 outputs various control signals via an output port. For example, the ECU 50 outputs control signals to a plurality of switching elements of the inverter 34. The ECU 50 calculates the motor 32 and the rotation speed Nm based on a control rotation position θmc based on the rotation position θm of the rotor of the motor 32 from the rotation position sensor 32a. The control rotation position θmc is calculated as the sum of the rotation position θm and an offset amount Δθos obtained by origin learning described later. The ECU 50 calculates a yaw angle θy based on a yaw rate ωy from a yaw rate sensor 68, calculates a roll angle θr based on a roll rate ωr from a roll rate sensor 69, and calculates a pitch angle θp based on a pitch rate ωp from a pitch rate sensor 70.

[0016] In the electric vehicle 20 of this embodiment configured as described above, the ECU 50 sets the required torque Td* required for driving (required of the drive shaft 26) based on the accelerator opening Acc and the vehicle speed V, sets the set required torque Td* as the torque command Tm* of the motor 32, and performs switching control of the multiple switching elements of the inverter 34 so that the motor 32 is driven by the torque command Tm*.

[0017] The inverter 34 is controlled by pulse width modulation (PWM) control. In the PWM control, first, d-axis and q-axis current commands Id* and Iq* in a dq-axis coordinate system are set based on a torque command Tm* of the motor 32. Next, assuming that the sum of the phase currents of each phase of the motor 32 is zero, the V-phase and W-phase phase currents Iv and Iw are coordinate-converted (three-phase-two-phase conversion) to the d-axis and q-axis currents Id and Iq using a control electrical angle θe based on a control rotation position θmc of the motor 32. Then, differences ΔId and ΔIq between the d-axis and q-axis current commands Id* and Iq* and the currents Id and Iq are calculated, and the d-axis and q-axis voltage commands Vd* and Vq* are calculated based on the calculated differences ΔId and ΔIq. Specifically, the d-axis and q-axis voltage commands Vd* and Vq* are calculated as the sum of a feedback term based on the differences ΔId and ΔIq and a feedforward term (the second term on the right side of Equations (1) and (2) described later) for canceling terms that interfere with each axis. After the d-axis and q-axis voltage commands Vd* and Vq* are calculated in this way, the d-axis and q-axis voltage commands Vd* and Vq* are coordinate-converted (2-phase to 3-phase conversion) into voltage commands Vu*, Vv*, and Vw* of each phase using the control electrical angle θe of the motor 32. Then, the voltage commands Vu*, Vv*, and Vw of each phase are compared with the carrier wave (triangular wave) voltage to generate PWM signals for the transistors T11 to T16, and the switching control of the transistors T11 to T16 is performed using the generated PWM signals.

[0018] Here, consider a case where the rotational position θm detected by the rotational position sensor 32a is used as it is (the offset amount Δθos is 0) as the control rotational position θmc of the motor 32. If the direction of the magnetic flux generated by the permanent magnet of the rotor of the motor 32 is the d-axis, and the axis perpendicular to the d-axis is the q-axis, the voltage equation of the motor 32 can be expressed by equations (1) and (2). In equations (1) and (2), "Vd" and "Vq" represent the voltages of the d-axis and q-axis, "Rm" represents the resistance value per phase, "Id" and "Iq" represent the currents of the d-axis and q-axis, "ωm" represents the angular velocity of the rotor, and "φd" and "φq" represent the magnetic flux of the d-axis and q-axis.

[0019] Vd=Rm Id-ωm φq (1) Vq=Rm Iq+ωm φd (2)

[0020] When there is no phase difference Δθ (offset error) between the rotational position θm of the motor 32 detected by the rotational position sensor 32a and the actual rotational position, the direction of the magnetic flux φm generated by the permanent magnet coincides with the d-axis (see FIG. 2(a)). Therefore, the magnetic fluxes φd and φq of the d-axis and q-axis can be expressed by the formulas (3) and (4). In the formulas (3) and (4), "Ld" and "Lq" indicate the inductances of the d-axis and q-axis. In this case, if the currents Id and Iq of the d-axis and q-axis are set to 0, the magnetic fluxes φd and φq of the d-axis and q-axis are φm,0, respectively, according to the formulas (3) and (4). Then, by substituting these into the formulas (1) and (2), the voltages Vd and Vq of the d-axis and q-axis are expressed by the formulas (5) and (6), respectively, and the voltage Vd of the d-axis is set to 0.

[0021] φd=Ld·Id+φm (3) φq=Lq Iq (4) Vd=0 (5) Vq = ωm φm (6)

[0022] On the other hand, if there is a phase difference Δθ (offset error) between the rotational position θm of the motor 32 detected by the rotational position sensor 32a and the actual rotational position, a phase difference Δθ is generated between the direction of the magnetic flux φm generated by the permanent magnet and the d-axis (see FIG. 2(b)). For this reason, if the d-axis and q-axis currents Id and Iq are set to 0, the d-axis and q-axis voltages Vd and Vq are expressed by equations (7) and (8), and when the motor 32 is rotating (when the angular velocity ωm is not 0), the d-axis voltage Vd does not become 0.

[0023] Vd=ωm φm sinΔθ (7) Vq=ωm φm cosΔθ (8)

[0024] In this way, if there is no offset error in the rotational position θm detected by the rotational position sensor 32a, the d-axis voltage Vd becomes 0 when the d-axis and q-axis currents Id and Iq are set to 0. On the other hand, if there is an offset error in the rotational position θm detected by the rotational position sensor 32a, even if the d-axis and q-axis currents Id and Iq are set to 0, the d-axis voltage Vd does not become 0 while the motor 32 is rotating. As described above, the rotational position θm detected by the rotational position sensor 32a is converted into an electrical angle θe and used for coordinate transformation (3-phase to 2-phase transformation, 2-phase to 3-phase transformation). Therefore, if there is an offset error in the rotational position θm, and an offset correction is not performed to cancel the offset error, it is difficult to perform the coordinate transformation appropriately and to output a torque corresponding to the torque command Tm* from the motor 32. Based on this, when origin learning (learning of offset amount Δθos) of the rotational position sensor 32a has not been completed after, for example, installation or replacement of the rotational position sensor 32a or the ECU 50, origin learning is executed in which, when the torque command Tm* is 0 while the motor 32 is rotating, the d-axis and q-axis currents Id, Iq are set to 0, and in this state, the rotational position θm detected by the rotational position sensor 32a is offset so that the d-axis voltage Vd has a value of 0, and the offset amount Δθos of the rotational position θm when the d-axis voltage Vd has a value of 0 is learned. When origin learning is completed in this manner, the sum of the rotational position θm and the offset amount Δθos is set to the control rotational position θmc.

[0025] In addition, in the electric vehicle 20, the ECU 50 basically performs turning control when the vehicle is turning. In the turning control, the ECU 50 corrects the torque command Tm* described above so as to suppress the delay in the change in the pitch angle θp relative to the change in the roll angle θr, and performs switching control of the multiple switching elements of the inverter 34 using the corrected torque command Tm*. This improves the ride comfort for the driver when turning.

[0026] Next, the operation of the electric vehicle 20 of this embodiment will be described. Fig. 3 is a flow chart showing an example of a processing routine executed by the ECU 50. This routine is executed repeatedly. When this routine is executed, the ECU 50 determines whether or not it is time to execute origin learning of the rotational position sensor 32a (step S100), and when it is determined that it is time to execute origin learning of the rotational position sensor 32a, the ECU 50 ends this routine.

[0027] When it is determined in step S100 that it is time to perform origin learning of the rotational position sensor 32a, the execution of the above-mentioned control during turning is prohibited (step S110), and this routine ends. In this case, even when the vehicle is turning, the control during turning is not executed. This makes it possible to suppress the influence of the control during turning (the influence of the correction of the torque command Tm*) from interfering with the origin learning of the rotational position sensor 32a. As a result, it is possible to suppress the origin learning of the rotational position sensor 32a from being unable to be performed appropriately.

[0028] In the electric vehicle 20 of the present embodiment described above, when the origin learning of the rotational position sensor 32a is being performed, the execution of the turning control is prohibited. This makes it possible to suppress the influence of the turning control (the influence of the correction of the torque command Tm*) from interfering with the origin learning of the rotational position sensor 32a. As a result, it is possible to suppress the origin learning of the rotational position sensor 32a from being unable to be performed appropriately.

[0029] In the above-described embodiment, the electric vehicle 20 is provided with the battery 36 as the power storage device. However, the electric vehicle 20 may be provided with a capacitor or the like as the power storage device.

[0030] In the above-described embodiment, the electric vehicle 20 is provided with a driving motor 32 and an inverter 34. However, the electric vehicle 20 may be provided in the form of a hybrid vehicle that includes an engine in addition to a driving motor and inverter, or in the form of a fuel cell vehicle that includes a fuel cell in addition to a driving motor and inverter.

[0031] The relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problems will be described below. In the embodiment, the motor 32 corresponds to the "motor", the rotational position sensor 32a corresponds to the "rotational position sensor", and the ECU 50 corresponds to the "control device".

[0032] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

[0033] The above describes embodiments for implementing the present disclosure, but the present disclosure is not limited to these embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0034] The present disclosure can be used in the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0035] 20 electric vehicle, 22a, 22b drive wheels, 24 differential gear, 26 drive shaft, 32 motor, 32a rotational position sensor, 32v current sensor, 34 inverter, 36 battery, 36i current sensor, 36v voltage sensor, 38 power line, 50 ECU, 60 start switch, 61 shift lever, 62 shift sensor, 63 accelerator pedal, 64 accelerator sensor, 65 brake pedal, 66 brake sensor, 67 vehicle speed sensor, 68 yaw rate sensor, 69 roll rate sensor, 70 pitch rate sensor, D11 to D16 diodes, T11 to T16 transistors.

Claims

[Claim 1] An electric vehicle including a motor for driving, a rotational position sensor for detecting a rotational position of the motor, and a control device for executing turning control that controls the motor based on the rotational position detected by the rotational position sensor and controls the motor so as to suppress a delay in a change in pitch angle relative to a change in roll angle when the vehicle is turning, The control device prohibits the execution of the turning control when the origin learning of the rotation position sensor is executed. Electric car.

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