Control device

Abstract

To suppress a decrease in control followability when a rate of change in motor rotation speed is large when switching between enabling and disabling harmonic superposition control.SOLUTION: Within a predetermined time after switching between enabling and disabling harmonic superposition control, if an absolute value of a rate of change of rotation speed, being an amount of change per unit time of the motor rotation speed, is less than a predetermined rate of change, an electric vehicle applies gradual change processing to d-axis and q-axis harmonic superposition current commands and / or d-axis and q-axis voltage command feedforward terms, and if the rate of change of rotation speed is the predetermined rate of change or more, prohibits the gradual change processing to the d-axis and q-axis harmonic superposition current commands and the d-axis and q-axis voltage command feedforward terms.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a control device. [Background technology]

[0002] Conventionally, a control device that controls a motor using a power conversion circuit has been proposed in which a command voltage for each phase of the motor is set and the applied voltage of the coil of each phase is controlled to the command voltage by operating the power conversion circuit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-195390 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a control device mounted on an electric vehicle that has a motor connected to drive wheels and an inverter that drives the motor, which determines whether harmonic superposition control is permitted by comparing the motor's rotation speed with a predetermined rotation speed, calculates the sum of d-axis and q-axis basic current commands based on the motor's torque command and the d-axis and q-axis harmonic superposition current commands based on whether harmonic superposition control is permitted as d-axis and q-axis current commands, calculates d-axis and q-axis voltage command feedback terms so that differences between the d-axis and q-axis current commands and the d-axis and q-axis currents are canceled out, calculates the sum of the d-axis and q-axis voltage command feedforward terms based on whether harmonic superposition control is permitted and the d-axis and q-axis voltage command feedback terms as d-axis and q-axis voltage commands, and controls the inverter based on the d-axis and q-axis voltage commands. In such a control device, when enabling / disabling harmonic superposition control, a sudden change in the d-axis and q-axis harmonic superposition current commands and voltage command feedforward terms can be prevented, resulting in torque shock. A possible solution is to gradually change the d-axis and q-axis harmonic superposition current commands and voltage command feedforward terms. However, when the absolute value of the rate of change of rotation speed is large, control tracking (torque tracking ability to a torque command) can be reduced. The control device of the present disclosure primarily aims to prevent a reduction in control tracking ability when the rate of change of the motor rotation speed is large when enabling / disabling harmonic superposition control. [Means for solving the problem]

[0005] The control device of the present disclosure employs the following means to achieve the above-mentioned main object: The control device of the present disclosure is mounted on an electric vehicle having a motor connected to drive wheels and an inverter that drives the motor, and determines whether or not the harmonic superposition control is permitted by comparing the rotation speed of the motor with a predetermined rotation speed, calculates the sum of d-axis and q-axis basic current commands based on a torque command of the motor and d-axis and q-axis harmonic superposition current commands based on whether or not the harmonic superposition control is permitted as d-axis and q-axis current commands, calculates d-axis and q-axis voltage command feedback terms so that differences between the d-axis and q-axis current commands and the d-axis and q-axis currents are canceled out, and calculates a voltage command feedforward term for the d-axis and q-axis based on whether or not the harmonic superposition control is permitted and a voltage command feedforward term for the d-axis and q-axis The control device calculates the sum of a rotation speed change rate, which is the amount of change per unit time of the motor rotation speed, as a d-axis and q-axis voltage command, and controls the inverter based on the d-axis and q-axis voltage commands, and if, within a predetermined time from switching whether or not to enable the harmonic superposition control, an absolute value of a rotation speed change rate, which is the amount of change per unit time of the motor rotation speed, is less than a predetermined change rate, performs gradual change processing on the d-axis and q-axis harmonic superposition current commands and / or the d-axis and q-axis voltage command feedforward terms, and if the rotation speed change rate is equal to or greater than the predetermined change rate, prohibits the gradual change processing on the d-axis and q-axis harmonic superposition current commands and the d-axis and q-axis voltage command feedforward terms.

[0006] In the control device of the present disclosure, the above-described process can suppress the occurrence of torque shock within a predetermined time from the switching of whether or not to enable harmonic superposition control, and when the absolute value of the rate of change of the motor rotation speed is less than a predetermined rate of change. Also, within a predetermined time from the switching of whether or not to enable harmonic superposition control, and when the rate of change of the rotation speed is equal to or greater than a predetermined rate of change, the control device can suppress a decrease in control follow-up ability (the ability of torque to follow a torque command). [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an electric vehicle 20 equipped with a control device according to an embodiment of the present disclosure. [Figure 2] 10 is a flowchart illustrating an example of a processing routine. [Figure 3]10 is a flowchart showing an example of a processing routine according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 equipped with a control device according to an embodiment of the present disclosure. As shown in the figure, the electric vehicle 20 according to the embodiment includes a motor 32, an inverter 34, a battery 36 as a power storage device, and an electronic control unit 50 (control device).

[0009] The motor 32 is configured as a three-phase AC 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 and 22b via a differential gear 24. The inverter 34 is connected to a power line 38. The inverter 34 includes six switching elements, namely, transistors T11 to T16, and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively. The transistors T11 to T16 are arranged in pairs, two on the source side and two on the sink side with respect to the positive and negative lines of the power line 38, respectively. The connection points of the paired transistors T11 to T16 are connected to the three-phase (U-phase, V-phase, W-phase) coils of the motor 32. Therefore, by adjusting the ratio of the on time of each pair of transistors T11 to T16 using the electronic control unit 50, a rotating magnetic field is generated in the three-phase coils of the motor 32, and the motor 32 (rotor) is rotated. The battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to a power line 38 together with the inverter 34. A capacitor 39 is attached to the positive and negative lines of the power line 38.

[0010] The electronic control unit 50 includes a microcomputer. The electronic control unit 50 receives inputs of the rotational position θm of the rotor of the motor 32 from a rotational position sensor 32a, phase currents Iu, Iv, and Iw of each phase of the motor 32 from current sensors 32u, 32v, and 32w, and the voltage Vb and current Ib of the battery 36 from voltage and current sensors. The electronic control unit 50 also receives inputs of an on / off signal from a power switch 60, the operating position (shift position SP) of a shift lever 61 from a shift position sensor 62, the depression amount (accelerator opening Acc) of an accelerator pedal 63 from an accelerator pedal position sensor 64, the depression amount (brake pedal position BP) of a brake pedal 65 from a brake pedal position sensor 66, and the vehicle speed V from a vehicle speed sensor 67. The electronic control unit 50 outputs control signals to transistors T11 to T16 of the inverter 34. The electronic control unit 50 calculates the electrical angle θe and the rotation speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32. The electronic control unit 50 calculates the state of charge (SOC) of the battery 36 based on the integrated value of the current Ib of the battery 36.

[0011] In the electric vehicle 20 of this embodiment configured in this manner, the electronic control unit 50 sets the required torque Td* required of the drive shaft 26 based on the accelerator opening Acc and the vehicle speed V, sets the torque command Tm* of the motor 32 so that the set required torque Td* is output to the drive shaft 26, and performs switching control of the transistors T11 to T16 of the inverter 34 so that the motor 32 is driven by the torque command Tm*.

[0012] Next, the operation of the electric vehicle 20 of this embodiment, particularly the control of the inverter 34, will be described. Figure 2 is a flowchart showing an example of a processing routine repeatedly executed by the electronic control unit 50. When this routine is executed, the electronic control unit 50 inputs the phase currents Iu, Iv, and Iw of each phase of the motor 32, the electrical angle θe, the rotation speed Nm, and the torque command Tm* (step S100), and uses the rotation speed Nm to calculate a rotation speed change rate ΔNm, which is the amount of change per unit time in the rotation speed Nm of the motor 32 (step S110). The rotation speed change rate ΔNm can be calculated, for example, by subtracting the previous value of the rotation speed Nm from the current value and dividing the result by the execution interval Δt of this routine.

[0013] Next, the phase currents Iu, Iv, and Iw of each phase are coordinate-converted (three-phase to two-phase conversion) to d-axis and q-axis currents Id and Iq using the electrical angle θe (step S120), and the d-axis and q-axis base current commands Idbs and Iqbs are set using the torque command Tm* (step S130). The base current commands Idbs and Iqbs can be set, for example, by applying the torque command Tm* to a map that has been determined in advance as the relationship between the torque command Tm* and the base current commands Idbs and Iqbs through experimentation, analysis, machine learning, or the like.

[0014] Then, it is determined whether the rotation speed Nm is less than a threshold value Nmref (step S140), and if it is determined that the rotation speed Nm is less than the threshold value Nmref, a determination is made as to whether harmonic superposition control is permitted (step S150). In this case, the torque command Tm*, the electrical angle θe, and the rotation speed Nm are used to set the d-axis and q-axis harmonic superposition current commands Idh and Iqh (step S160). In this case, the harmonic superposition current commands Idh and Iqh can be set by applying the torque command Tm*, the electrical angle θe, and the rotation speed Nm to a map that has been determined in advance as the relationship between the torque command Tm*, the electrical angle θe, the rotation speed Nm, and the harmonic superposition current commands Idh and Iqh through experimentation, analysis, machine learning, or the like. Next, the sum of the d-axis and q-axis fundamental current commands Idbs, Iqbs and the harmonic superimposed current commands Idh, Iqh is calculated as the d-axis and q-axis current commands Id*, Iq* (step S170). Then, d-axis and q-axis voltage command FB (feedback) terms Vdfb, Vqfb are calculated by current feedback control so that the differences ΔId, ΔIq between the d-axis and q-axis current commands Id*, Iq* and the currents Id, Iq are canceled out (step S180). In addition, voltage command FF (feedforward) terms Vdff, Vqff are set using the torque command Tm*, electrical angle θe, and rotation speed Nm (step S190). In this case, the voltage command FF terms Vdff and Vqff can be set by applying the torque command Tm*, the electrical angle θe, and the rotation speed Nm to a map that has been determined in advance by experiment, analysis, machine learning, or the like as the relationship between the torque command Tm*, the electrical angle θe, the rotation speed Nm, and the voltage command FF terms Vdff and Vqff.

[0015] If it is determined in step S140 that the rotation speed Nm is equal to or greater than the threshold value Nmref, a prohibition determination for harmonic superposition control is made (step S200). In this case, the d-axis and q-axis harmonic superposition current commands Idh and Iqh are both set to 0 (step S210). Subsequently, similar to the processing in steps S170 and S180, the d-axis and q-axis current commands Id* and Iq* and voltage command FB terms Vdfb and Vqfb are calculated (steps S220 and S230). Then, voltage command FF terms Vdff and Vqff are set using torque command Tm* (step S240). In this case, the voltage command FF terms Vdff and Vqff can be set by applying torque command Tm* to a map that is predetermined by experiment, analysis, machine learning, or the like as the relationship between torque command Tm* and voltage command FF terms Vdff and Vqff.

[0016] After step S190 or step S240, it is determined whether a predetermined time has elapsed since the switch between the permission and prohibition determinations for the harmonic superposition control (step S250), and it is also determined whether the absolute value of the rotation speed change rate ΔNm is less than a threshold value ΔNmref (step S260). Here, the threshold value ΔNmref is a threshold value for determining whether there is a sudden change in the rotation speed Nm due to the occurrence or elimination of slippage of the drive wheels 22a, 22b.

[0017] If it is determined in step S250 that a predetermined time has elapsed since the switch between the enable / disable determination of harmonic superposition control and if it is determined in step S260 that the absolute value of the rotation speed change rate ΔNm is less than the threshold value ΔNmref, then gradual change processing of the voltage command FF terms Vdff, Vqff is executed (step S270), and the process proceeds to step S280. In this processing, for example, gradual change processing such as rate processing or smoothing processing is performed on the voltage command FF terms Vdff, Vqff, and the processed values ​​are reset as the voltage command FF terms Vdff, Vqff. This makes it possible to suppress sudden changes in the voltage command FF terms Vdff, Vqff.

[0018] If it is determined in step S250 that the predetermined time has not elapsed since the switch between the permission and prohibition of harmonic superposition control, or if it is determined in step S260 that the absolute value of the rotation speed change rate ΔNm is equal to or greater than the threshold value ΔNmref, the process skips step S270 and proceeds to step S280, whereby the voltage command FF terms Vdff and Vqff can be quickly set to the values ​​after the switch between permission and prohibition of harmonic superposition control.

[0019] Next, the d-axis and q-axis voltage command FF terms Vdff, Vqff and voltage command FB terms Vdfb, Vqfb are summed to obtain d-axis and q-axis voltage commands Vd*, Vq* (step S280). The voltage commands Vd*, Vq* are then converted to phase voltage commands Vu*, Vv*, Vw* for each phase using the electrical angle θe (two-phase to three-phase conversion) (step S290). The inverter 34 is then controlled using the phase voltage commands Vu*, Vv*, Vw* (step S300), and the routine ends. In this process, for example, the phase voltage commands Vu*, Vv*, Vw* are compared with a carrier wave to generate PWM signals for the transistors T11-T16 of the inverter 34, thereby controlling the switching of the transistors T11-T16.

[0020] In the electronic control unit 50 mounted on the electric vehicle 20 according to the embodiment described above, when switching between enabling and disabling harmonic superposition control (within a predetermined time after switching), if the absolute value of the rotation speed change rate ΔNm is less than a threshold value ΔNmref, the electronic control unit 50 executes gradual change processing of the voltage command FF terms Vdff and Vqff. However, if the absolute value of the rotation speed change rate ΔNm is equal to or greater than the threshold value ΔNmref, the electronic control unit 50 does not execute gradual change processing of the voltage command FF terms Vdff and Vqff. As a result, in the former case, sudden changes in the voltage command FF terms Vdff and Vqff and thus the phase voltage commands Vu*, Vv*, and Vw* can be suppressed, thereby suppressing the occurrence of torque shock. Meanwhile, in the latter case, the voltage command FF terms Vdff and Vqff and thus the phase voltage commands Vu*, Vv*, and Vw* can be quickly set to values ​​after switching between enabling and disabling harmonic superposition control, thereby suppressing a decrease in control followability (the ability of torque to follow a torque command).

[0021] In the embodiment described above, the electronic control unit 50 executes the processing routine of Fig. 2. However, instead, it may execute the processing routine of Fig. 3. The processing routine of Fig. 3 differs from the processing routine of Fig. 2 in that the processing of steps S250 to S270 is omitted and the processing of steps S162 to S166 and S212 to S216 is added. In the processing routine of Fig. 3, after each of steps S160 and S210, the electronic control unit 50 determines, as in steps S250 and S260, whether a predetermined time has elapsed since the switch between the permission determination and the prohibition determination of the harmonic superposition control, and whether the absolute value of the rotation speed change rate ΔNm is less than a threshold value ΔNmref (steps S162 to S164, S212 to S214).

[0022] If it is determined in steps S162 and S212 that a predetermined time has elapsed since the switch between the enable and disable determination of harmonic superposition control, and if it is determined in steps S164 and S214 that the absolute value of the rotation speed change rate ΔNm is less than the threshold value ΔNmref, gradual change processing is performed on the d-axis and q-axis harmonic superposition current commands Idh and Iqh (steps S166 and S216), and the process proceeds to steps S170 and S220. In these processes, for example, gradual change processing such as rate processing or smoothing processing is performed on the harmonic superposition current commands Idh and Iqh, and the processed values ​​are reset as the harmonic superposition current commands Idh and Iqh. This makes it possible to suppress sudden changes in the harmonic superposition current commands Idh and Iqh.

[0023] If it is determined in steps S162 and S212 that the predetermined time has not elapsed since the switch between the enable and disable determination of harmonic superposition control, or if it is determined in steps S164 and S214 that the absolute value of the rotation speed change rate ΔNm is equal to or greater than the threshold value ΔNmref, the program proceeds to steps S170 and S220 without executing steps S166 and S216. This allows the gradual change processing of the harmonic superposition current commands Idh and Iqh to be quickly set to the values ​​after the switch between the enable and disable of harmonic superposition control.

[0024] In this modification, when the permissibility of harmonic superposition control is switched (within a predetermined time after the switching), if the absolute value of the rotational speed change rate ΔNm is less than a threshold value ΔNmref, the gradual change processing of the harmonic superposition current commands Idh, Iqh is executed, whereas if the absolute value of the rotational speed change rate ΔNm is equal to or greater than the threshold value ΔNmref, the gradual change processing of the harmonic superposition current commands Idh, Iqh is not executed. As a result, in the former case, sudden changes in the harmonic superposition current commands Idh, Iqh and thus the phase voltage commands Vu*, Vv*, Vw* are suppressed, thereby suppressing the occurrence of torque shock. Meanwhile, in the latter case, the harmonic superposition current commands Idh, Iqh and thus the phase voltage commands Vu*, Vv*, Vw* are quickly set to the values ​​after the permissibility of harmonic superposition control is switched, thereby suppressing a deterioration in control followability (the ability of torque to follow a torque command).

[0025] In the above-described embodiment, the electric vehicle 20 is configured to include a motor 32 for driving. However, instead of this, for example, the electric vehicle may be configured as a hybrid vehicle having a motor and an engine, or as a fuel cell vehicle having a motor and a fuel cell.

[0026] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0027] The present disclosure is applicable to the control device manufacturing industry and the like. [Explanation of symbols]

[0028] 20 electric vehicles, 32 motors, 34 inverters, 50 electronic control units.

Claims

[Claim 1] a control device mounted on an electric vehicle having a motor connected to drive wheels and an inverter that drives the motor, the control device determining whether or not the harmonic superposition control is permitted by comparing a rotation speed of the motor with a predetermined rotation speed, calculating, as d-axis and q-axis current commands, sums of d-axis and q-axis basic current commands based on a torque command of the motor and d-axis and q-axis harmonic superposition current commands based on whether or not the harmonic superposition control is permitted, calculating d-axis and q-axis voltage command feedback terms so that differences between the d-axis and q-axis current commands and the d-axis and q-axis currents are canceled out, calculating, as d-axis and q-axis voltage commands, sums of the d-axis and q-axis voltage command feedforward terms based on whether or not the harmonic superposition control is permitted and the d-axis and q-axis voltage command feedback terms, and controlling the inverter based on the d-axis and q-axis voltage commands, If, within a predetermined time from the switching of whether or not to permit the harmonic superposition control, an absolute value of a rate of change in rotation speed, which is a change amount per unit time of the rotation speed of the motor, is less than a predetermined rate of change, a gradual change process is performed on the d-axis and q-axis harmonic superposition current commands and / or the d-axis and q-axis voltage command feedforward terms, and if the rate of change in rotation speed is equal to or greater than the predetermined rate of change, the gradual change process on the d-axis and q-axis harmonic superposition current commands and the d-axis and q-axis voltage command feedforward terms is prohibited. Control device.

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