Electric vehicle

Abstract

To execute harmonic superposition control while suppressing deterioration of electric power consumption, acceleration performance, drivability, etc.SOLUTION: The electrically powered vehicle includes a motor for traveling, an inverter for driving the motor, and a control device for controlling the inverter. When a predetermined condition including a condition that a torque command is equal to or higher than a predetermined torque and a condition that a rotation speed of the motor is equal to or lower than a predetermined rotation speed is satisfied at the time of executing harmonic superimposition control for controlling the inverter using a current command obtained by superimposing a harmonic current on a basic current based on a torque command of the motor, the control device sets a harmonic current for a measure against motor noise based on the rotation speed of the motor and limits the torque command such that the current command falls within an allowable range based on the set harmonic current.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, an electric vehicle has been proposed in which a voltage component that cancels out harmonic components of an output current that are generated due to harmonic components contained in an induced voltage of a synchronous generator motor is superimposed on the output voltage of an inverter (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2928594 Summary of the Invention [Problem to be solved by the invention]

[0004] In such electric vehicles, harmonic superposition control may be performed to control the inverter using a current command in which harmonic currents are superimposed on a fundamental current based on a torque command of the motor. In this case, it may be impossible to sufficiently superimpose harmonic currents near the maximum torque of the motor. In contrast, if the motor torque is uniformly and significantly limited in order to sufficiently superimpose harmonic currents, there is a risk that power consumption, acceleration, drivability, and the like will deteriorate. The electric vehicle of the present disclosure has a primary objective of performing harmonic superposition control while suppressing deterioration in power consumption, acceleration, drivability, and the like. [Means for solving the problem]

[0005] The electric vehicle of the present disclosure employs the following means to achieve the above-mentioned primary object. The electric vehicle of the present disclosure is an electric vehicle including a traction motor, an inverter that drives the motor, and a control device that controls the inverter, wherein the control device, when executing harmonic superposition control to control the inverter using a current command in which a harmonic current is superimposed on a basic current based on a torque command of the motor, sets the harmonic current for reducing motor noise based on the rotational speed of the motor when predetermined conditions are met, including a condition in which the torque command is equal to or greater than a predetermined torque and a condition in which the rotational speed of the motor is equal to or less than a predetermined rotational speed, and limits the torque command based on the set harmonic current so that the current command is within an allowable range.

[0006] In the electric vehicle disclosed herein, when harmonic superposition control is performed to control the inverter using a current command in which a harmonic current is superimposed on a basic current based on a torque command of the motor, if predetermined conditions are met, including a condition in which the torque command is equal to or greater than a predetermined torque and a condition in which the motor rotation speed is equal to or less than a predetermined rotation speed, a harmonic current for reducing motor noise is set based on the motor rotation speed, and the torque command is limited based on the set harmonic current so that the current command falls within an allowable range. This prevents unnecessary restriction of the torque command, and makes it possible to perform harmonic superposition control while preventing deterioration of electric power consumption, acceleration, drivability, etc. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an electric vehicle 10 according to an embodiment of the present disclosure. [Figure 2] 4 is a flowchart showing an example of a processing routine repeatedly executed by the ECU 50. [Figure 3] 10 is a time chart showing the upper limit torque Tmmax and rotation speed Nm of the motor 22, and whether or not a high torque NV countermeasure mode is in effect. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of an electric vehicle 10 according to an embodiment of the present disclosure. As shown in the figure, the electric vehicle 10 according to the embodiment includes a motor 22, an inverter 24, a battery 26 as a power storage device, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0009] Motor 22 is configured as a three-phase AC motor and includes a rotor with a permanent magnet embedded in a rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound around a stator core. The rotor of motor 22 is connected to drive shaft 16, which is connected to drive wheels 12a, 12b via differential gear 14.

[0010] The inverter 24 is connected to a positive line 28p and a negative line 28n to which the battery 26 is connected. The inverter 24 includes six switching elements, i.e., transistors T11-T16, 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, on the source side and two at the sink side of the positive line 28p and the negative line 28n. The connection points of two pairs of transistors T11-T16 are connected to three-phase (U-phase, V-phase, W-phase) coils of the motor 22, respectively. Therefore, the ECU 50 adjusts the proportion of the on-time of the paired transistors T11-T16, thereby forming a rotating magnetic field in the three-phase coils of the motor 22, and the motor 22 (rotor) is rotated.

[0011] Battery 26 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery. The positive and negative terminals of battery 26 are connected to positive and negative lines 28p and 28n. Smoothing capacitor 30 is connected to positive and negative lines 28p and 28n.

[0012] The ECU 50 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. The ECU 50 receives signals from various sensors. For example, the ECU 50 receives the rotational position θm of the rotor of the motor 22 from the rotational position sensor 22a, and the phase currents Iu, Iv, and Iw of the motor 22 from the current sensors 22u, 22v, and 22w. The ECU 50 also receives the voltage Vb of the battery 26 from the voltage sensor 26v, the current Ib of the battery 26 from the current sensor 26i, and the temperature Tb of the battery 26 from the temperature sensor 26t. The ECU 50 also receives the voltage VH of the capacitor 30 from the voltage sensor 30v. Other inputs include an on / off signal from a power switch 60, the operating position of a shift lever 61 (shift position SP) from a shift position sensor 62, the depression amount of an accelerator pedal 63 (accelerator opening Acc) from an accelerator pedal position sensor 64, the depression amount of a brake pedal 65 (brake pedal position BP) from a brake pedal position sensor 66, a vehicle speed V from a vehicle speed sensor 67, an acceleration G from an acceleration sensor 68, and a road gradient θrd (positive values ​​on the uphill side) from a gradient sensor 69. The ECU 50 outputs switching control signals to transistors T11 to T16 of the inverter 24. The ECU 50 calculates the electrical angle θe and rotation speed Nm of the motor 22 based on the rotational position θm of the rotor of the motor 22, and calculates the charge storage rate SOC of the battery 26 based on the integrated value of the current Ib of the battery 26.

[0013] In the electric vehicle 10 of this embodiment configured as described above, the ECU 50 sets a required torque Td* required for traveling (required of the drive shaft 16) based on the accelerator pedal position Acc and the vehicle speed V, sets a temporary torque command Tmtmp for the motor 22 so that the vehicle travels with the set required torque Td*, and limits (upper limit guards) the set temporary torque Tmtmp with an upper limit torque Tmmax to set a torque command Tm* for the motor 22. Then, the ECU 50 performs switching control of the transistors T11 to T16 of the inverter 24 based on the torque command Tm*.

[0014] Here, the control of the inverter 24 will be described. First, the ECU 50 performs coordinate transformation (three-phase to two-phase transformation) to convert the phase currents Iu, Iv, and Iw of the motor 22 into d-axis and q-axis currents Id and Iq using the electrical angle θe of the motor 22. Next, the ECU 50 sets the d-axis and q-axis fundamental currents Idbs and Iqbs based on the torque command Tm* of the motor 22, and sets the d-axis and q-axis current commands Id* and Iq* by superimposing the d-axis and q-axis harmonic currents Idh and Iqh on the set d-axis and q-axis fundamental current commands Idbs and Iqbs. Then, the ECU 50 calculates the d-axis and q-axis voltage commands Vd* and Vq* by current feedback control so that the differences between the d-axis and q-axis current commands Id* and Iq* and the currents Id and Iq are canceled out. In addition, the d-axis and q-axis voltage commands Vd* and Vq* are coordinate-converted (2-phase to 3-phase conversion) to voltage commands Vu*, Vv*, and Vw* for each phase using the electrical angle θe of the motor 22, and PWM signals for the transistors T11 to T16 are generated by comparing these voltage commands Vu*, Vv*, and Vw with the carrier voltage, and the generated PWM signals for the transistors T11 to T16 are used to control the switching of the transistors T11 to T16. Control of the inverter 24 using such harmonic currents Idh and Iqh is called "harmonic superposition control."

[0015] Next, the operation of the electric vehicle 10 of this embodiment, particularly the harmonic superposition control, will be described. Fig. 2 is a flowchart showing an example of a processing routine repeatedly executed by the ECU 50. When this routine is executed, the ECU 50 first determines whether or not predetermined conditions are met, that is, the torque command Tm* of the motor 22 is equal to or greater than a threshold value Tmref, the acceleration G is equal to or less than a threshold value Gref, and the rotation speed Nm of the motor 22 is equal to or less than a threshold value Nmref (steps S100 to S120). Here, the processing of steps S100 to S120 is processing for determining whether or not a state exists in which motor noise is a problem, such as when the rotation speed Nm of the motor 22 remains within the resonant rotation speed range of the motor 22 for a certain period of time on an uphill road, for example. The threshold values ​​Tmref, Gref, and Nmref are determined in advance through experiments, analysis, or the like.

[0016] If it is determined in steps S100-S120 that the torque command Tm* of the motor 22 is less than the threshold value Tmref, the acceleration G is greater than the threshold value Gref, or the rotation speed Nm of the motor 22 is greater than the threshold value Nmref, and thus the predetermined conditions are not met, the normal mode is set (step S130). In this case, the upper limit torque Tmmax is set to the rated torque Tmr of the motor 22 (step S132), the temporary torque Tmtmp is limited (upper limit guard) by the upper limit torque Tmmax, and the torque command Tm* of the motor 22 is set (step S134), and harmonic superposition control is performed using the torque command Tm* (step S140), and this routine ends. In the harmonic superposition control in the normal mode, a current of a constant electrical order may be used as the harmonic current Ih, which is composed of d-axis and q-axis harmonic currents Idh and Iqh, or a current of an electrical order based on the rotation speed Nm of the motor 22 may be used.

[0017] If it is determined in steps S100 to S120 that the predetermined conditions—that the torque command Tm* of the motor 22 is equal to or greater than the threshold value Tmref, the acceleration G is equal to or less than the threshold value Gref, and the rotation speed Nm of the motor 22 is equal to or less than the threshold value Nmref—are satisfied, a high-torque NV (Noise Vibration) countermeasure mode is set to suppress noise and vibration of the motor 22 (step S140). In this case, a problematic electrical order Nnv is set based on the rotation speed Nm of the motor 22 (step S142), and the presence or absence of the problematic electrical order Nnv is determined (step S144). The problematic electrical order Nv is an electrical order at which stator resonance or the like occurs, and can be obtained, for example, by applying the rotation speed Nm of the motor 22 to a map previously determined by experiment, analysis, machine learning, or the like as the relationship between the rotation speed Nm of the motor 22 and the problematic electrical order Nnv, and deriving the corresponding problematic electrical order Nnv. Examples of the problematic electrical order Nnv include 6, 12, 18, 24, and so on. Even when the predetermined conditions are met, there may be cases where there is no problematic electrical order Nnv.

[0018] If it is determined in step S144 that there is no problematic electrical order Nnv, the processes of steps S132 to S136 described above are executed, that is, the same harmonic superposition control as in the normal mode is executed, and then this routine is terminated.

[0019] If it is determined in step S144 that there is a problematic electrical order Nnv, the harmonic current Ih is set based on the problematic electrical order Nnv (step S146). In this case, the harmonic current Ih is set as a current vector having d-axis and q-axis harmonic currents Idh and Iqh as components for motor noise countermeasures, specifically, for suppressing the component of the problematic electrical order Nnv. The harmonic current Ih can be obtained, for example, by applying the problematic electrical order Nnv to a map that has been determined in advance as the relationship between the problematic electrical order Nnv and the harmonic current Ih through experiment, analysis, machine learning, or the like, to derive the corresponding harmonic current Ih.

[0020] Next, an upper limit torque Tmmax is set based on the harmonic current Ih (step S150), the temporary torque Tmtmp is limited (upper limit guard) by the upper limit torque Tmmax to set a torque command Tm* for the motor 22 (step S152), harmonic superposition control is performed using the torque command Tm* and the harmonic current Ih (step S154), and this routine ends. The upper limit torque Tmmax in this case is set as a relatively large torque that brings the d-axis and q-axis current commands Id* and Iq* into an allowable range (e.g., the upper limit of the allowable range) when the harmonic current Ih is used, for example, a torque that makes the peak value of the pulsation of the output torque of the motor 22 equal to the rated torque Tmr when the inverter 24 is controlled based on the d-axis and q-axis current commands Id* and Iq* using the harmonic current Ih. In this case, the upper limit torque Tmmax is obtained by applying the harmonic current Ih to a map that has been previously determined by experiment, analysis, machine learning, or the like as the relationship between the harmonic current Ih and the upper limit torque Tmmax, and deriving the corresponding upper limit torque Tmmax. By performing harmonic superposition control using the torque command Tm* and harmonic current Ih of the motor 22 obtained in this manner, it is possible to prevent unnecessary restriction of the torque command Tm*. As a result, it is possible to perform harmonic superposition control while preventing deterioration in power consumption, acceleration, drivability, etc.

[0021] FIG. 3 is a time chart showing the upper limit torque Tmmax of the motor 22, the rotation speed Nm, and whether or not the high-torque NV countermeasure mode is enabled. As shown in the figure, when a predetermined condition is met and the high-torque NV countermeasure mode is enabled, if there is a problematic electrical order Nnv based on the rotation speed Nm of the motor 22 (values ​​Nnv1, Nnv2, and Nnv3 in FIG. 3, e.g., the 24th, 18th, and 12th electrical orders, respectively), the upper limit torque Tmmax is reduced relative to the rated torque Tmr based on the harmonic current Ih based on the problematic electrical order Nnv. This prevents excessive restriction of the torque command Tm* compared to a case where the torque command Tm* is significantly reduced by uniformly significantly reducing the upper limit torque Tmmax. As a result, harmonic superposition control can be performed while preventing deterioration in power consumption, acceleration, drivability, and the like.

[0022] In the electric vehicle 10 of the embodiment described above, when it is determined that a predetermined condition is met and there is a problematic electrical order Nnv based on the rotation speed Nm of the motor 22, the harmonic current Ih is set based on the problematic electrical order Nnv, an upper limit torque Tmmax is set based on the set harmonic current Ih, the temporary torque Tmtmp is limited (upper limit guard) by the upper limit torque Tmmax to set the torque command Tm* of the motor 22, and harmonic superposition control is performed using the torque command Tm* and the harmonic current Ih. This prevents unnecessary limitations on the torque command Tm* and makes it possible to perform harmonic superposition control while preventing deterioration of power consumption, acceleration performance, drivability, etc.

[0023] In the above-described embodiment, the predetermined condition is an AND condition of the torque command Tm* of the motor 22 being equal to or greater than the threshold value Tmref, the acceleration G being equal to or less than the threshold value Gref, and the rotation speed Nm of the motor 22 being equal to or less than the threshold value Nmref. However, instead of the condition of the acceleration G being equal to or less than the threshold value Gref, a condition of the road surface gradient θrd being equal to or greater than the threshold value θrdref may be used.

[0024] In the above-described embodiment, the electric vehicle 10 includes the motor 22 connected to the drive wheels 12a, 12b and the inverter 24 that drives the motor 22. However, the electric vehicle 10 may also include a second motor connected to a second drive wheel and a second inverter that drives the second motor. In this case, when limiting the torque of the motor 22 in the high-torque NV countermeasure mode, the torque of the second motor may be increased by the amount of the limit. This can prevent a decrease in the total torque of the vehicle.

[0025] In the above-described embodiment, the battery 26 is used as the power storage device, but this is not limiting. For example, a capacitor or the like may be used as the power storage device.

[0026] In the above-described embodiment, the electric vehicle 10 is provided with a motor 22 for driving, but the electric vehicle may be provided in the form of a hybrid vehicle that has an engine in addition to a motor, or in the form of a fuel cell vehicle that has a fuel cell in addition to a motor.

[0027] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the motor 22 corresponds to the "motor," the inverter 24 corresponds to the "inverter," the battery 26 corresponds to the "battery," and the ECU 50 corresponds to the "controller."

[0028] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0029] 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]

[0030] The present disclosure is applicable to the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0031] 10 Electric vehicle, 22 Motor, 24 Inverter, 250 ECU (controller), D11-D16 Diodes, T11-T16 Transistors.

Claims

[Claim 1] An electric vehicle including a motor for driving, an inverter that drives the motor, and a control device that controls the inverter, When executing harmonic superposition control to control the inverter using a current command in which a harmonic current is superimposed on a basic current based on a torque command of the motor, if predetermined conditions are met, including a condition that the torque command is equal to or greater than a predetermined torque and a condition that the rotation speed of the motor is equal to or less than a predetermined rotation speed, the control device sets the harmonic current for motor noise countermeasures based on the rotation speed of the motor, and limits the torque command based on the set harmonic current so that the current command is within an allowable range. Electric car.

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