Electric vehicle control method and electric vehicle control device

Abstract

The present invention provides an electric vehicle control method that generates a predetermined target sound from an electric motor used for driving an electric vehicle. The control method includes: calculating, according to a target torque to be output by the electric motor, a basic voltage command for determining a voltage to be applied to the electric motor; generating an additional voltage command having a specific frequency corresponding to the target sound; calculating a final voltage command by adding the additional voltage command to the basic voltage command; and generating the target sound from the electric motor while the target torque is output by the electric motor by applying the voltage according to the final voltage command to the electric motor. Then, as the target torque becomes larger, the amplitude of the additional voltage command is made smaller, and as the target torque becomes smaller, the amplitude of the additional voltage command is made larger.

Description

Control method for electric vehicles, and control device for electric vehicles

[0001] The present invention relates to a control method and control device for electric vehicles.

[0002] JP2022-063981A discloses a motor sound control system that superimposes harmonic currents onto the fundamental wave current that controls the motor in order to generate motor sound. In this motor sound control system, the superimposed harmonic currents are adjusted so that the sound pressure level of the motor sound increases as the motor speed increases, in order to generate a motor sound that is pleasant for the driver.

[0003] In electric vehicles, the motor driven by an inverter may produce a sound known as magnetostrictive noise or excitation noise. In recent years, magnetostrictive noise has been actively utilized, for example, as a motor sound.

[0004] However, magnetostrictive noise changes depending on the rotational state of the electric motor. For example, if the output torque of the electric motor changes, the sound pressure level of the magnetostrictive noise changes accordingly. Therefore, when actively generating magnetostrictive noise from an electric motor used to drive an electric vehicle, if the output torque of the electric motor changes in accordance with the amount of accelerator operation, the sound pressure level of the magnetostrictive noise changes, and there is a problem that the way the magnetostrictive noise is heard will differ from what was intended.

[0005] The present invention aims to provide a control method and control device for an electric vehicle that can generate magnetostrictive noise of a predetermined audible quality from an electric motor used to drive the electric vehicle.

[0006] One aspect of the present invention is a control method for an electric vehicle that generates a predetermined target sound from an electric motor used to drive the electric vehicle. In this control method, a basic voltage command is calculated to determine the voltage to be applied to the electric motor according to the target torque that the electric motor should output, an additional voltage command having a specific frequency corresponding to the target sound is generated, a final voltage command is calculated by adding the additional voltage command to the basic voltage command, and a voltage according to the final voltage command is applied to the electric motor, thereby causing the electric motor to output the target torque while generating the target sound from the electric motor. Furthermore, the amplitude of the additional voltage command is reduced as the target torque increases, and the amplitude of the additional voltage command is increased as the target torque decreases.

[0007] Figure 1 is a block diagram showing the schematic configuration of an electric vehicle. Figure 2 is a block diagram showing the configuration of the voltage command generation unit. Figure 3 is a block diagram showing the configuration of the rotation state estimation unit. Figure 4 is a block diagram showing the configuration of the sound control unit. Figure 5 is a graph schematically showing the characteristics of the d-axis inductance and q-axis inductance. Figure 6 is an explanatory diagram showing the current flowing through the electric motor. Figure 7 is a flowchart relating to the electric motor control of this embodiment. Figure 8 is a graph schematically showing the change in the sound pressure level of magnetostrictive noise in a comparative example. Figure 9 is a graph schematically showing the sound pressure level of magnetostrictive noise in this embodiment. Figure 10 is a graph schematically showing the sound pressure level of magnetostrictive noise in this embodiment. Figure 11 is a block diagram showing the schematic configuration of an electric vehicle according to the second embodiment. Figure 12 is a flowchart relating to the electric motor control in the second embodiment.

[0008] Embodiments of the present invention will be described below with reference to the drawings.

[0009] [First Embodiment] Figure 1 is a block diagram showing the schematic configuration of an electric vehicle 100. The electric vehicle 100 is a vehicle that generates all or part of its driving force by electric power, such as an electric vehicle or a hybrid vehicle. As shown in Figure 1, the electric vehicle 100 includes a battery 10, an inverter 11, an electric motor 12, a speaker 13, and a controller 14.

[0010] Battery 10 is a DC power source that stores power supplied to the electric motor 12, etc. Battery 10 is rechargeable and is charged, for example, by an external charging device (not shown) or by power generated by the electric motor 12 through regenerative control (regenerative power). The state of battery 10 is measured as appropriate. For example, the DC voltage V output by battery 10. ｄｃ This is acquired as needed by the voltage sensor 21.

[0011] The inverter 11 (INV) converts the DC power output by the battery 10 into AC power and supplies it to the motor 12. This drives the motor 12. When the motor 12 generates regenerative power, the inverter 11 converts the regenerative power, which is AC power, into DC power and supplies it to the battery 10. This charges the battery 10 with regenerative power. The inverter 11 is configured using a bridge circuit, and the multiple switching elements constituting the bridge circuit are controlled by so-called PWM (Pulse Width Modulation) control.

[0012] The electric motor 12 is the power source for the electric vehicle 100 and is used for driving and braking the electric vehicle 100. Specifically, the electric motor 12 is connected to the drive wheels via gears, a drive shaft, etc., and the torque T output by the electric motor 12 generates the driving force and braking force (regenerative braking force) of the electric vehicle 100.

[0013] In this embodiment, the motor 12 is a three-phase AC synchronous motor. Therefore, the rotation state of the motor 12 is controlled by adjusting the current or voltage of each phase U, V, and W to generate a predetermined torque T corresponding to the accelerator operation amount, etc. The current flowing through each phase U, V, and W (hereinafter referred to as phase current i) ｕｖｗ This can be acquired as needed by the current sensor 22.

[0014] Furthermore, the electric motor 12 driven by the inverter 11 may produce a sound called magnetostrictive noise or excitation noise (hereinafter referred to as magnetostrictive noise). In typical electric vehicles, magnetostrictive noise is usually considered noise produced by the electric motor 12. However, in this embodiment, the electric vehicle 100 effectively utilizes magnetostrictive noise by controlling its frequency and sound pressure level, thereby making the magnetostrictive noise a predetermined sound (hereinafter referred to as the target sound). That is, the electric vehicle 100 may intentionally generate magnetostrictive noise with a predetermined frequency and sound pressure level so that the target sound is produced by the electric motor 12.

[0015] In this embodiment, as an example, the electric vehicle 100 outputs all or part of the vehicle approach warning sound using the magnetostrictive sound of the electric motor 12. That is, in this embodiment, all or part of the vehicle approach warning sound is the target sound to be realized by the magnetostrictive sound. Therefore, the electric motor 12 substantially constitutes all or part of the vehicle approach warning device.

[0016] Speaker 13 is a sound output device that outputs sound or voice towards the inside or outside of the electric vehicle 100. In this embodiment, speaker 13 constitutes a vehicle approach warning device that outputs all or part of the vehicle approach warning sound towards the outside of the electric vehicle 100. The sound or voice output by speaker 13 is a reproduction of pre-prepared sound or voice data. Hereinafter, in order to distinguish it from the magnetostrictive noise emitted by the electric motor 12, the sound output from speaker 13 will be referred to as the reproduced sound.

[0017] The controller 14 is a control device that comprehensively controls each part of the electric vehicle 100. The controller 14 is composed of, for example, one or more computers and is programmed to control each part at a predetermined control cycle.

[0018] For example, the controller 14 controls the accelerator pedal input amount A. ｐｏ By switching the inverter 11 according to (not shown) etc., the current supplied to each phase of the motor 12 and the voltage supplied to each phase of the motor 12 are controlled. As a result, the motor 12 controls the accelerator operation amount A ｐｏIt outputs a torque T corresponding to the above. As a result, driving force or braking force is generated in the electric vehicle 100. In other words, the controller 14 functions as a control device for the electric motor 12, or as a drive (braking) control device for the electric vehicle 100.

[0019] The controller 14 functions as a vehicle approach warning device (AVAS) that emits a vehicle approach warning sound either by magnetostrictive noise generated by the electric motor 12 or by a reproduced sound output from the speaker 13.

[0020] Vehicle approach warning sounds are sounds (warning sounds) used to inform pedestrians and others that an electric vehicle is in motion. The frequency band, minimum sound pressure level, maximum sound pressure level, etc., are determined by the country or region. Typically, vehicle approach warning sounds consist of at least two sounds from different frequency bands. Furthermore, vehicle approach warning sounds are required to be output at a sound pressure level above the predetermined minimum sound pressure level for each frequency band. In addition, from a noise perspective, a maximum sound pressure level is also defined for vehicle approach warning sounds. For this reason, vehicle approach warning sounds need to be output at a generally constant sound pressure level that falls within the specified sound pressure level range.

[0021] In this embodiment, as an example, the electric vehicle 100 has a first frequency f １ The first tone and the second frequency f ２ The vehicle approach warning sound is composed of a second sound having the characteristics of a magnetostrictive tone. The first sound is a sound that can be output by magnetostrictive tone, and the second sound is a sound that cannot be output by magnetostrictive tone. Therefore, when it is necessary to output a vehicle approach warning sound, the controller 14, in principle, outputs the first sound by magnetostrictive tone and the second sound by regenerated tone. The controller 14 also outputs the first and second sounds at approximately constant sound pressure levels.

[0022] In addition, in this embodiment, the electric motor 12 is not equipped with a sensor (rotation detector) for detecting the rotation state of the electric motor 12, such as the position of the magnetic poles, and the controller 14 estimates the rotation state of the electric motor 12. In other words, the controller 14 controls the electric motor 12 by so-called sensorless control.

[0023] More specifically, the controller 14 includes a current command generation unit 31, a voltage command generation unit 32, a coordinate conversion unit 33, a PWM control unit 34, a coordinate conversion unit 35, a rotation state estimation unit 36, and a sound control unit 37.

[0024] The current command generation unit 31 calculates (generates) the dq-axis current command i ＊ based on the torque command T ｄｑ ＊ and the rotational speed N [rpm] of the motor 12.

[0025] The torque command T ＊ is a parameter representing the target value of the torque T to be output by the motor 12 (hereinafter referred to as the target torque), and is appropriately set according to the accelerator operation amount A ｐｏ and the rotational state of the motor 12. In this embodiment, for simplicity, the controller 14 acquires the torque command T ＊ and controls the rotation of the motor 12 based on the acquired torque command T ＊ . However, the controller 14 can acquire the accelerator operation amount A ｐｏ etc. and calculate (set) the torque command T ＊ itself.

[0026] The rotational speed N is one of the parameters representing the rotational state of the motor 12. In this embodiment, since it is sensorless control, the rotational speed N is an estimated value calculated by the rotation state estimation unit 36. The rotational speed N is calculated based on the estimated value of the electrical angular velocity ω.

[0027] The dq-axis current command i ｄｑ ＊ is a parameter representing the target value of the current to be passed through the motor 12 in terms of the current components in the dq-axis coordinate system that rotates with the rotor of the motor 12. The dq-axis current command i ｄｑ ＊ consists of the d-axis current command i ｄ that determines the target value of the d-axis current i ｄ ＊ and the q-axis current command i ｑ that determines the target value of the q-axis current i ｑ ＊ . The d-axis current i ｄi is the current component that primarily contributes to the generation of magnetic flux. ｑ is torque T (or torque command T) ＊ This is the current component that contributes to the generation of ).

[0028] In this embodiment, the current command generation unit 31 generates the torque command T ＊ and rotational speed N, and dq axis current command i ｄｑ ＊ It has a current command map (not shown) that associates and . Therefore, the current command generation unit 31 refers to this current command map and generates the torque command T ＊ and the dq axis current command i corresponding to the rotational speed N ｄｑ ＊ Perform the calculation.

[0029] The current command map is predetermined based on experiments or simulations, etc., to output the maximum torque T with the minimum current. In other words, the current command map is the dq axis current command i when performing so-called MTPA (Maximum Torque Per Ampere) control. ｄｑ ＊ It defines this.

[0030] The voltage command generation unit 32 generates a torque command T for the electric motor 12. ＊ The dq-axis voltage command v outputs a torque T corresponding to the output. ｄｑ ＊ The following is calculated (generated): dq axis voltage command v ｄｑ ＊ This parameter represents the target value of the voltage to be applied to the electric motor 12, expressed as a voltage component in the dq-axis time coordinate system. dq-axis voltage command v ｄｑ ＊ The d-axis voltage v ｄ The d-axis voltage command v sets the target value for this. ｄ ＊ And the q-axis voltage v ｑ The q-axis voltage command v sets the target value for this. ｑ ＊ This consists of the following. Below, the dq-axis voltage command v that the voltage command generation unit 32 ultimately outputs ｄｑ ＊ In simple terms, the final voltage command v ｄｑ ＊ That's what they say.

[0031] When the modulation ratio MF in the PWM control of the inverter 11 is relatively small, the voltage command generation unit 32 uses a so-called current vector control method to generate a torque command T for the motor 12. ＊ A basic dq-axis voltage command (hereinafter referred to as the first basic voltage command v) for outputting torque T corresponding to the torque T. ｄｑ１ ＊ The first basic voltage command v is calculated as follows: ｄｑ１ ＊ Based on this, the final voltage command v ｄｑ ＊ The first basic voltage command v is calculated. ｄｑ１ ＊ The d-axis voltage v ｄ The first basic d-axis voltage command v represents the target value. ｄ１ ＊ And the q-axis voltage v ｑ The first basic q-axis voltage command v represents the target value. ｑ１ ＊ It consists of the following. The voltage command generation unit 32 generates the dq axis current i ｄｑ The dq axis current command i ｄｑ ＊ The first basic voltage command v ｄｑ１ ＊ The voltage command generation unit 32 determines the first basic voltage command v ｄｑ１ ＊ When calculating the torque command T ＊ DC voltage V ｄｃ , and based on the rotational speed N, the d-axis voltage command v ｄ ＊ and q-axis voltage command v ｑ ＊ Reduces interference.

[0032] When the modulation ratio MF in the PWM control of the inverter 11 is relatively large, the voltage command generation unit 32 uses a so-called voltage phase control method to generate a torque command T for the motor 12. ＊ A basic dq-axis voltage command (hereinafter referred to as the second basic voltage command v) for outputting torque T corresponding to the torque T. ｄｑ２ ＊ The second basic voltage command v is calculated as follows: ｄｑ２ ＊ Based on this, the final voltage command v ｄｑ＊ is calculated. The second basic voltage command v ｄｑ２ ＊ is composed of the second basic d-axis voltage command v ｄ representing the target value of the d-axis voltage v ｄ２ ＊ and the second basic q-axis voltage command v ｑ representing the target value of the q-axis voltage v ｑ２ ＊ . The voltage command generation unit 32 generates a voltage norm command V ＊ and a voltage phase command α ｄｑ based on the torque command T ｄｃ , the dq-axis current i ａ ＊ , the DC voltage V ＊ , and the rotational speed N. Then, the voltage command generation unit 32 calculates the second basic voltage command v ａ ＊ using the voltage norm command V​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​It consists of the following: Additional voltage command v ｄｑｈ ＊ This is the first basic voltage command v ｄｑ１ ＊ and the second basic voltage command v ｄｑ２ ＊ A specific frequency (hereinafter referred to as the specific frequency ω) that is higher than the fundamental frequency ω ｈ This is a voltage command having the following characteristics: The voltage command generation unit 32 generates the first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ , a specific frequency ω ｈ By superimposing the high frequency, the final voltage command v ｄｑ ＊ Perform the calculation.

[0036] specific frequency ω ｈ In particular, the frequency may be set to an integer multiple of the fundamental frequency ω. In this case, the additional voltage command v ｄｑｈ ＊ This is the first basic voltage command v ｄｑ１ ＊ and the second basic voltage command v ｄｑ２ ＊ It is composed of harmonics. That is, the voltage command generation unit 32 generates the first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ By superimposing harmonics, the final voltage command v ｄｑ ＊ This can be calculated. In this embodiment, a specific frequency ω ｈ The frequency is set to at least a frequency higher than the fundamental frequency ω, but is not limited to frequencies that are integer multiples of the fundamental frequency ω. That is, the additional voltage command v ｄｑｈ ＊ This is the first basic voltage command v ｄｑ１ ＊ and the second basic voltage command v ｄｑ２ ＊ While it is a high-frequency wave, it is not necessarily a harmonic.

[0037] In this embodiment, the additional voltage command v ｄｑｈ ＊ The specific frequency ωｈ , and additional voltage command v ｄｑｈ ＊ Amplitude V ｈ This is set by the sound control unit 37 depending on whether or not a vehicle approach warning sound is required.

[0038] The coordinate transformation unit 33 performs a coordinate transformation from the dq axis coordinate system to the UVW coordinate system, thereby generating the dq axis voltage command v ｄｑ ＊ From three-phase voltage command v ｕｖｗ ＊ The three-phase voltage command v is calculated. ｕｖｗ ＊ The U-phase voltage v ｕ The target value of the U-phase voltage command v ｕ ＊ V-phase voltage v ｖ The target value is the V-phase voltage command v ｖ ＊ , and W-phase voltage v ｗ The target value of the W-phase voltage command v ｗ ＊ It consists of.

[0039] More specifically, the coordinate transformation unit 33, based on the electrical angle θ of the electric motor 12, sets the dq axis voltage command v according to the following equation (2). ｄｑ ＊ From three-phase voltage command v ｕｖｗ ＊ The following is calculated. Note that the electrical angle θ is one of the parameters that represent the rotation state of the electric motor 12. In this embodiment, since it is sensorless control, the electrical angle θ is an estimated value calculated by the rotation state estimation unit 36.

[0040]

[0041] The PWM control unit 34 receives a three-phase voltage command v ｕｖｗ ＊ and DC voltage V ｄｃ Based on this, a drive signal D determines the timing for switching each switching element of the inverter 11 on and off. ＊ The PWM control unit 34 generates this drive signal D. ＊ Based on this, each switching element is switched. As a result, the motor 12 receives the final voltage command v ｄｑ ＊A voltage corresponding to the torque command T is applied. As a result, the motor 12 receives the torque command T. ＊ It outputs a torque T (target torque) corresponding to the value. Then, the first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ , a specific frequency ω ｈ Additional voltage command v ｄｑｈ ＊ By superimposing (high frequency), the final voltage command v ｄｑ ＊ When this is being generated, the motor 12 emits a specific frequency ω due to the magnetostrictive noise. ｈ The frequency f corresponding to the frequency ｓ [Hz] and amplitude V ｈ Sound pressure level P corresponding to ｓ It generates the target sound it possesses.

[0042] The coordinate transformation unit 35 performs a coordinate transformation from the UVW coordinate system to the dq axis coordinate system, thereby determining the phase current i ｕｖｗ From the dq axis current i ｄｑ The dq axis current i is calculated. ｄｑ is the d-axis current i ｄ and q-axis current i ｑ This is the detected value. Specifically, the coordinate transformation unit 35 calculates the phase current i based on the electrical angle θ according to the following equation (3). ｕｖｗ From the dq axis current i ｄｑ The following calculation is performed. The electrical angle θ is an estimated value calculated by the rotation state estimation unit 36, as described above.

[0043]

[0044] In this embodiment, the current sensor 22 controls the phase current i ｕｖｗ Of these, U-phase current i ｕ and V-phase current i ｖ It detects the W-phase current i. ｗ This is calculated according to the following formula (4).

[0045]

[0046] The rotation state estimation unit 36 ​​determines the dq axis current i ｄｑBased on these factors, parameters representing the rotational state of the electric motor 12 are estimated (calculated). In this embodiment, the rotational state estimation unit 36 ​​estimates the electric angle θ [rad] and electric angular velocity ω [rad / s] of the electric motor 12. The rotational state estimation unit 36 ​​also calculates the rotational speed N [rpm] of the electric motor 12 based on the electric angular velocity ω by unit conversion.

[0047] Specifically, the rotation state estimation unit 36 ​​estimates the electrical angle θ, electrical angular velocity ω, and rotational speed N by using the first estimation method, the second estimation method, or a combination of both.

[0048] The first estimation method is the fundamental wave voltage command (v ｄｑ１ ＊ ,v ｄｑ２ ＊ This method estimates the rotational state of the motor 12 based on the response current of high-frequency or harmonic components superimposed on the final voltage command v. ｄｑ ＊ and dq axis current i ｄｑ Based on this, the rotation state of the electric motor 12 is estimated. In particular, in this embodiment, the fundamental wave voltage command (v ｄｑ１ ＊ ,v ｄｑ２ ＊ An additional voltage command v to produce magnetostrictive noise in relation to ) ｄｑｈ ＊ When superimposed, the rotation state estimation unit 36 ​​issues an additional voltage command v to generate this magnetostrictive noise. ｄｑｈ ＊ Based on the response current, the rotation state of the motor 12 is estimated. That is, in this embodiment, an additional voltage command v is used to generate magnetostrictive noise. ｄｑｈ ＊ This is also used to estimate the rotational state of the electric motor 12.

[0049] The second estimation method is a method of estimating the rotation state of the electric motor 12 using a so-called magnetic flux observer. In the second estimation method, the dq axis current i ｄｑ Based on this, the rotational state of the electric motor 12 is estimated.

[0050] The sound control unit 37 controls the sound output to the inside or outside of the electric vehicle 100 by reproduced sound, magnetostrictive sound, or both.

[0051] The sound control unit 37 controls the target frequency f ｓ ＊ and target sound pressure level P ｓ ＊ Based on this, the frequency and sound pressure level of the reproduced sound are controlled. The sound control unit 37 also controls the target frequency f ｓ ＊ Target sound pressure level P ｓ ＊ , and dq axis current command i ｄｑ ＊ Based on this, the frequency and sound pressure level of the magnetostrictive sound are controlled.

[0052] Target frequency f ｓ ＊ This parameter represents the frequency of the sound to be output inside or outside the electric vehicle 100. When outputting this sound with the playback sound, the sound control unit 37 sets the target frequency f ｓ ＊ The sound data to be played is selected accordingly. When outputting this sound using magnetostrictive sound, the sound control unit 37 sets the target frequency f ｓ ＊ Additional voltage command v ｄｑｈ ＊ The frequency (specific frequency ω ｈ Set ).

[0053] Target sound pressure level P ｓ ＊ This parameter represents the sound pressure level of the sound to be output inside or outside the electric vehicle 100. When outputting this sound with the playback sound, the sound control unit 37 sets the sound pressure level of the playback sound to the target sound pressure level P. ｓ ＊ The output of the reproduced sound is adjusted so that it reaches the target sound pressure level P. ｓ ＊ The additional voltage command v ｄｑｈ ＊ Amplitude V ｈ Set or adjust it.

[0054] However, when generating magnetostrictive sound in this manner, the sound control unit 37 sets the target sound pressure level Pｓ ＊ A constant amplitude V corresponding to the amplitude V ｈ Instead of setting the amplitude V according to the target torque of the electric motor 12, ｈ The size is changed or adjusted as appropriate. In this embodiment, the sound control unit 37 controls the dq axis current command i ｄｑ ＊ (especially the q-axis current command i) ｑ ＊ ) Amplitude V ｈ This causes the torque command T to vary. This is essentially the torque command T ＊ The amplitude V corresponds to the amplitude V. ｈ This is equivalent to varying the dq axis current command i. ｄｑ ＊ Instead, Torque command T ＊ The amplitude V corresponds to the amplitude V. ｈ It can be varied.

[0055] More specifically, the sound control unit 37 controls the target sound pressure level P ｓ ＊ A predetermined amplitude V corresponding to the specified amplitude V １ Based on this, the q-axis current command i ｑ ＊ (Torque Command T) ＊ The larger the amplitude V becomes ｈ It reduces the q-axis current command i. ｑ ＊ (Torque Command T) ＊ The smaller the amplitude V, the smaller the amplitude V ｈ This increases the sound pressure level of the magnetostrictive sound. As a result, the sound control unit 37 sets the sound pressure level of the magnetostrictive sound to the target sound pressure level P. ｓ ＊ To match (maintain) or follow the same value.

[0056] The sound control unit 37 controls the target frequency f ｓ ＊ and target sound pressure level P ｓ ＊ By accepting the input, the system uses the reproduced sound and magnetostrictive sound to determine the target frequency f ｓ ＊ and target sound pressure level P ｓ ＊Various sounds can be output depending on the situation. However, in this embodiment, for simplicity, the sound control unit 37 constitutes a vehicle approach warning device that controls the vehicle approach warning sound. For this reason, in this embodiment, the target frequency f ｓ ＊ and target sound pressure level P ｓ ＊ This is a predetermined fixed value that specifies the frequency and sound pressure level of the designated vehicle approach warning sound. Specifically, the target frequency f ｓ ＊ and target sound pressure level P ｓ ＊ The frequency of the first tone is f １ and sound pressure level P ｓ１ and the frequency f of the second tone ２ and sound pressure level P ｓ２ Specify.

[0057] Figure 2 is a block diagram showing the configuration of the voltage command generation unit 32. It includes a first basic voltage command generation unit 41, a second basic voltage command generation unit 42, a final voltage command generation unit 43, and a control mode determination unit 44.

[0058] The first basic voltage command generation unit 41 generates a first basic voltage command v for current vector control. ｄｑ１ ＊ The following calculation is performed. Specifically, the first basic voltage command generation unit 41 calculates the dq axis current i as shown in equation (5) below. ｄｑ dq axis current command i ｄｑ ＊ The first basic voltage command v is controlled by PI (Proportional Integral) control, which matches or follows the first basic voltage command v ｄｑ１ ＊ Perform the calculation.

[0059]

[0060] In addition, in equation (5), K ｐ１ This is a proportional gain, and K ｉ１ V is the integral gain. "s" is the differential operator. ｄ－ｄｃｐｌ ＊ and V ｑ－ｄｃｐｌ ＊ This is a so-called decoupling voltage. In this embodiment, the first basic voltage command generation unit 41 generates the torque command T＊ DC voltage V ｄｃ and rotational speed N and decoupling voltage V ｄ－ｄｃｐｌ ＊ , V ｑ－ｄｃｐｌ ＊ It has a decoupling voltage table that has been pre-associated with the following through experimentation or simulation. Therefore, the first basic voltage command generation unit 41 generates the torque command T by referring to this decoupling voltage table. ＊ DC voltage V ｄｃ and the decoupling voltage V corresponding to the rotational speed N ｄ－ｄｃｐｌ ＊ , V ｑ－ｄｃｐｌ ＊ Perform the calculation.

[0061] The second basic voltage command generation unit 42 generates a second basic voltage command v for voltage phase control. ｄｑ２ ＊ The following is calculated. Specifically, the second basic voltage command generation unit 42 generates the voltage norm command V as follows: ａ ＊ and voltage phase command α ＊ The second basic voltage command v is calculated based on these values. ｄｑ２ ＊ Perform the calculation.

[0062] The second basic voltage command generation unit 42 generates a DC voltage V according to the following formula (6): ｄｃ Based on the modulation ratio MF, the voltage norm command V ａ ＊ The voltage norm command V is calculated. ａ ＊ This refers to the voltage norm V in voltage phase control. ａ These are the parameters that define it.

[0063]

[0064] The second basic voltage command generation unit 42 generates a torque command T ＊ DC voltage V ｄｃ And based on the rotational speed N, the voltage phase target value α ｆｆ ＊ The torque command T is calculated. In this embodiment, the second basic voltage command generation unit 42 generates the torque command T. ＊ DC voltage V ｄｃ And rotational speed N and voltage phase target value α ｆｆ＊ It has a voltage phase map that pre-associates these through experimentation or simulation. Therefore, the second basic voltage command generation unit 42 generates the torque command T by referring to this voltage phase map. ＊ DC voltage V ｄｃ and the voltage phase target value α corresponding to the rotational speed N ｆｆ ＊ Perform the calculation.

[0065] Furthermore, the second basic voltage command generation unit 42 generates the dq axis current i ｄｑ Based on the rotational speed N, the estimated torque T ｅｓｔ The estimated torque T is calculated. ｅｓｔ This is an estimated value of the torque T actually output by the electric motor 12. In this embodiment, the second basic voltage command generation unit 42 generates the dq axis current i ｄｑ And rotational speed N and estimated torque T ｅｓｔ It has an estimated torque table that has been pre-associated with the dq axis current i by experiment or simulation. Therefore, the second basic voltage command generation unit 42 refers to this estimated torque table to generate the dq axis current i ｄｑ and estimated torque T corresponding to rotational speed N ｅｓｔ Perform the calculation.

[0066] Then, the second basic voltage command generation unit 42 generates the torque command T ＊ Estimated torque T ｅｓｔ Based on this, the voltage phase correction value α ｆｂ ＊ The second basic voltage command generation unit 42 calculates the estimated torque T as shown in equation (7) below. ｅｓｔ Torque command T ＊ The voltage phase correction value α is corrected by PI control that matches or follows the specified value. ｆｂ ＊ The calculation is performed. Note that in equation (7), K ｐ２ This is a proportional gain, and K ｉ２ is the integral gain. Also, "s" is the differential operator.

[0067]

[0068] The second basic voltage command generation unit 42 generates a voltage phase target value α ｆｆ ＊and voltage phase correction value α ｆｂ ＊ By adding this, the final voltage phase command α ＊ We perform the calculation, that is, α ＊ = α ｆｆ ＊ +α ｆｂ ＊ That is the case.

[0069] As described above, the voltage norm command V ａ ＊ and voltage phase command α ＊ When this is calculated, the second basic voltage command generation unit 42 generates the second basic voltage command v according to the following equation (8). ｄｑ２ ＊ Perform the calculation.

[0070]

[0071] The final voltage command generation unit 43 generates the control mode selection signal M ｓｗ Based on this, the first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ One of the following is selected. Then, the final voltage command generation unit 43 generates the final voltage command v from the selected basic voltage command. ｄｑ ＊ Used for: Control mode selection signal M ｓｗ This is set by the control mode determination unit 44.

[0072] Furthermore, the final voltage command generation unit 43 receives the amplitude V of the voltage signal to be superimposed on the basic voltage command from the sound control unit 37. ｈ and specific frequency ω ｈ In some cases, the following may be input. Thus, amplitude V ｈ and specific frequency ω ｈ When the superposition of voltage signals is determined by the input, the final voltage command generation unit 43 determines that the amplitude and frequency are amplitude V ｈ and specific frequency ω ｈ The additional voltage command v ｄｑｈ ＊ It generates the following: Then, it adds an additional voltage signal v to the selected basic voltage command. ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ＊ Perform the calculation.

[0073] Additional voltage command v ｄｑｈ ＊ The additional voltage command v is set according to equation (9) below. In equation (9), "t" is time. ｄｑｈ ＊ Of these, the d-axis voltage command v ｄ ＊ The additional d-axis voltage command v is added to it. ｄｈ ＊ The amplitude and frequency are V, respectively. ｈ ,ω ｈ This is the cosine wave. Similarly, the additional voltage command v ｄｑｈ ＊ Of these, the q-axis voltage command v ｑ ＊ The additional q-axis voltage command v is added to it. ｑｈ ＊ The amplitude and frequency are V, respectively. ｈ ,ω ｈ It is a sine wave.

[0074]

[0075] In this embodiment, when the sound control unit 37 needs to emit a vehicle approach warning sound, or when it estimates the rotation state of the electric motor 12 by the first estimation method, it sends an amplitude V to the final voltage command generation unit 43. ｈ and specific frequency ω ｈ The input is used to determine the superposition of voltage signals. Therefore, when there is no need to emit a vehicle approach warning sound and the rotation state of the electric motor 12 is estimated by the second estimation method, the final voltage command generation unit 43 generates the control mode selection signal M ｓｗ The first basic voltage command v selected based on this ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ Either of these will be used as the final voltage command v ｄｑ ＊ Output as follows.

[0076] In addition, the final voltage command generation unit 43 monitors whether or not regenerative control is being performed. For example, the final voltage command generation unit 43 generates a torque command T ＊Based on the rotational speed N, it is possible to determine whether or not regenerative control is being performed. If it is determined that regenerative control is not being performed, the final voltage command generation unit 43 continues the control calculation described above.

[0077] On the other hand, when it is determined that regenerative control is being performed, the final voltage command generation unit 43 further monitors whether the electric vehicle 100 (electric motor 12) has substantially stopped. For example, the final voltage command generation unit 43 can determine whether the electric vehicle 100 has substantially stopped by comparing the magnitude of the rotational speed N |N| with a predetermined threshold ε.

[0078] Specifically, if |N| > ε, the final voltage command generation unit 43 determines that the electric vehicle 100 is not stopped. In this case, the final voltage command generation unit 43 continues the control calculation described above.

[0079] On the other hand, if |N| ≤ ε, the final voltage command generation unit 43 determines that the electric vehicle 100 has stopped. In this case, the final voltage command generation unit 43 generates an additional voltage command v to generate magnetostrictive noise. ｄｑｈ ＊ The superposition is stopped. Therefore, the final voltage command generation unit 43 uses the selected basic voltage command as the final voltage command v ｄｑ ＊ It outputs as follows. In this situation, in effect, the first basic voltage command v ｄｑ１ ＊ This is selected. Therefore, the final voltage command generation unit 43 generates the first basic voltage command v ｄｑ１ ＊ The final voltage command v ｄｑ ＊ Output as follows.

[0080] The control mode determination unit 44 determines, based on the modulation index MF, which control mode to select: current vector control or voltage phase control. The control mode determination unit 44 then issues a control mode selection signal M according to the determination result. ｓｗ The settings are configured and input to the final voltage command generation unit 43.

[0081] The control mode determination unit 44 determines, for example, when the modulation rate MF is equal to the modulation rate threshold TH ＭＦWhen the above conditions are met, it is determined that voltage phase control should be selected, and the modulation rate MF is equal to the modulation rate threshold TH. ＭＦ When it is smaller than the modulation rate threshold TH, it is determined that current vector control should be selected. ＭＦ This is predetermined by fitting, based on experiments or simulations.

[0082] The control mode determination unit 44 determines the modulation rate threshold TH according to the current control mode. ＭＦ By changing this, hysteresis can be introduced into the switching between current vector control and voltage phase control. For example, the control mode determination unit 44 sets the modulation rate threshold TH ＭＦ As such, the first modulation rate threshold TH ＭＦ１ And the first modulation rate threshold TH ＭＦ１ The second modulation rate threshold TH is greater than ＭＦ２ Set (TH ＭＦ１ <TH ＭＦ２ ). And when the current control mode is current vector control, the control mode determination unit 44 determines that the modulation rate MF is the second modulation rate threshold TH ＭＦ２ When the above conditions are met, it is determined that voltage phase control should be selected. On the other hand, when the current control mode is voltage phase control, the control mode determination unit 44 determines that the modulation rate MF is the first modulation rate threshold TH ＭＦ１ When the value becomes smaller than a certain threshold, it is determined that current vector control should be selected. This prevents frequent switching of control modes (chattering).

[0083] Figure 3 is a block diagram showing the configuration of the rotation state estimation unit 36. As shown in Figure 3, the rotation state estimation unit 36 ​​includes a first estimation unit 46, a second estimation unit 47, and a final estimated value calculation unit 48.

[0084] The first estimation unit 46 estimates the rotation state of the electric motor 12 by the first estimation method. That is, the first estimation unit 46 estimates the final voltage command v ｄｑ ＊ Based on the current response of the high-frequency components contained in the signal, the rotation state of the motor 12 is estimated. In this embodiment, the first estimation unit 46 receives an additional voltage command v ｄｑｈ ＊ The rotational state of the electric motor 12 is estimated based on the current response.

[0085] Specifically, the first estimation unit 46 uses, for example, a high-pass filter or a band-pass filter to determine the dq-axis current i ｄｑ From there, the final voltage command v ｄｑ ＊ The current component corresponding to the frequency of the high-frequency components contained is extracted. In this embodiment, as described above, a specific frequency ω is selected for the basic voltage command. ｈ Additional voltage command v ｄｑｈ ＊ These are superimposed. Therefore, the first estimation unit 46 determines the dq axis current i ｄｑ From there, additional voltage command v ｄｑｈ ＊ The current response component, i.e., a specific frequency ω ｈ A high-frequency component having (hereinafter referred to as a specific high-frequency current i) ｄｑｈ Extract the specific high-frequency current i. ｄｑｈ is the d-axis current i ｄ The specific high-frequency d-axis current i included ｄｈ And the q-axis current i ｑ The specific high-frequency q-axis current i included ｑｈ It consists of and .

[0086] The first estimation unit 46 determines this specific high-frequency current i ｄｑｈ The positive phase component (in-phase component) of [c ｐ ,s ｐ ] and the reversed phase component (mirror phase component) [c ｎ ,s ｎ The positive-sequence component [c] is calculated according to equations (10) and (11) below. ｐ ,s ｐ ] and reversed phase component [c ｎ ,s ｎ The first estimation unit 46 calculates the positive-sequence component [c ｐ ,s ｐ ] and reversed phase component [c ｎ ,s ｎ ] to twice the frequency (2ω ｈ In some cases, filtering is performed to reduce the gain of the signal.

[0087]

[0088] Furthermore, the first estimation unit 46 calculates the specific high-frequency current i according to the following formula (12): ｄｑｈThe positive phase component [c ｐ ,s ｐ ] and the reversed phase component [c ｎ ,s ｎ Based on ], the phase error θ γ１ Perform the calculation.

[0089]

[0090] The first estimation unit 46 has a phase error θ as shown in equation (13) below. γ１ Based on PI control, the estimated electrical angular velocity ω by the first estimation method is obtained. １ The first estimation unit 46 calculates the estimated electrical angular velocity ω by unit conversion. １ From the first estimation method, the estimated rotational speed N １ The calculation is performed. In equation (13), K ｐａ This is a proportional gain, and K ｉａ is the integral gain. Also, "s" is the differential operator.

[0091]

[0092] The first estimation unit 46 estimates the electrical angular velocity ω as shown in the following equation (14). １ By integrating, the estimated electric angle θ according to the first estimation method is obtained. １ Perform the calculation.

[0093]

[0094] In the rotation state estimation method (first estimation method) by the first estimation unit 46 described above, the d-axis inductance L ｄ and q-axis inductance L ｑ (L ｄ = L ｑ ), when the denominator of the right-hand side of equation (12) is approximately zero, the phase error θ γ１ This becomes uncertain. Therefore, the first estimation method is the salient polarity of the motor 12, i.e., L ｄ ≠L ｑ This is based on the premise that, for example, the q-axis inductance L ｑ The d-axis inductance L changes, ｄ and q-axis inductance L ｑ When the values ​​are close together, the accuracy of estimating the rotation state may decrease.

[0095] The second estimation unit 47 estimates the rotation state of the electric motor 12 using the second estimation method. That is, the second estimation unit 47 estimates the rotation state of the electric motor 12 using a magnetic flux observer. The magnetic flux observer used by the second estimation unit 47 is configured as follows.

[0096] First, the voltage equation for the electric motor 12 is expressed by the following equation (15) in the dq-axis coordinate system. In equation (15), "R" is the winding resistance [Ω], and "Φ" is the magnetic flux [Wb]. "ω" is the electrical angular velocity, and "s" is the differential operator.

[0097]

[0098] This voltage equation has a phase error θ with respect to the dq axis coordinate system. γ２ When converted to a representation in a γδ axis coordinate system having , it becomes as shown in equation (16) below. Each parameter in equation (16) is expressed by equations (17) to (19).

[0099]

[0100] This is the rotor magnetic flux Φ ｍ = [Φ ｍγ , Φ ｍδ When expressed in a state-space representation with ] as the state variable, we obtain the state equation shown in equation (20) and the output equation shown in equation (21) below.

[0101]

[0102] According to the above state equation and output equation, the state variable is the rotor magnetic flux Φ ｍ = [Φ ｍγ , Φ ｍδ The magnetic flux observer that estimates [ ] can be expressed by the following equation (22) using a 2x2 gain matrix G and an identity matrix I. The gain matrix G is set in advance based on experiments or simulations.

[0103]

[0104] Using this magnetic flux observer, the rotor magnetic flux Φ in the γδ axis coordinate system ｍ = [Φ ｍγ , Φ ｍδIf ] is estimated, the second estimation unit 47 determines the phase error θ of the γδ axis. γ２ This can be calculated using the following formula (23).

[0105]

[0106] Therefore, the second estimation unit 47 calculates the phase error θ as shown in equation (24) below. γ２ Based on PI control, the estimated electrical angular velocity ω by the second estimation method is obtained. ２ The second estimation unit 47 calculates the estimated electrical angular velocity ω by unit conversion. ２ From the second estimation method, the estimated rotational speed N ２ The calculation is performed. In equation (24), K ｐｂ This is a proportional gain, and K ｉｂ is the integral gain. Also, "s" is the differential operator.

[0107]

[0108] Furthermore, the second estimation unit 47 estimates the electrical angular velocity ω as shown in the following equation (25). ２ By integrating, the estimated electric angle θ according to the second estimation method is obtained. ２ Perform the calculation.

[0109]

[0110] The rotation state estimation method (second estimation method) by the second estimation unit 47 described above is based on the d-axis inductance L ｄ and q-axis inductance L ｑ When (L ｄ = L ｑ ), the rotation state can be estimated with high accuracy. On the other hand, the d-axis inductance L ｄ and q-axis inductance L ｑ When the difference is large, the accuracy of estimating the rotation state may decrease.

[0111] The final estimated value calculation unit 48 calculates the final estimated values ​​of the electrical angle θ and rotational speed N based on the estimation results from the first estimation method and the second estimation method. In this embodiment, the final estimated value calculation unit 48 calculates the estimated electrical angle θ １ , θ ２The final electrical angle θ (estimated value) is calculated by the weighted sum of these values. Similarly, the final estimated value calculation unit 48 calculates the estimated rotational speed N １ , N ２ The final rotational speed N (estimated value) is calculated by the weighted sum of these values. That is, the final estimated value calculation unit 48 calculates the final electrical angle θ and rotational speed N according to the following equations (26) and (27).

[0112]

[0113] In equations (26) and (27), the weighting coefficient w １ ,w ２ It is variable, however, the weight coefficient w １ ,w ２ At least lol １ +w ２ It is set to satisfy = 1. In this embodiment, the final estimated value calculation unit 48 calculates a weighting coefficient w according to the rotation speed N (previous value). １ ,w ２ Change the weight coefficient w. １ ,w ２ The rotational speed N is a predetermined rotational speed N Ａ If the following is true, w １ = 1 and w ２ = is set to 0. The rotational speed N is set to a predetermined rotational speed N Ａ A predetermined rotational speed N greater than Ｂ If it is more than that, w １ = 0 and w ２ = is set to 1. Then, the rotational speed N is set to a predetermined rotational speed N Ａ Larger than, at a predetermined rotational speed N Ｂ When it is smaller than, the weight coefficient w １ The weight coefficient w is set to decrease linearly from 1 to 0. ２ It is set to increase linearly from 0 to 1.

[0114] In other words, N ≤ N Ａ In this case, the final estimated value calculation unit 48 calculates the estimated electric angle θ substantially according to the first estimation method. １ and estimated rotational speed N １ This is output as the final electrical angle θ and rotational speed N. N ≥ N ＢIn this case, the final estimated value calculation unit 48 calculates the estimated electric angle θ substantially according to the second estimation method. ２ and estimated rotational speed N ２ This is output as the final electrical angle θ and rotational speed N. Ａ <N<N Ｂ In this case, the final estimated value calculation unit 48 combines the estimation result of the first estimation method and the estimation result of the second estimation method to finally calculate a reasonable electrical angle θ and rotational speed N.

[0115] Predetermined rotational speed N Ａ , N Ｂ These are, in principle, predetermined based on experiments or simulations.

[0116] However, as stated above, N < N Ｂ In that case, the estimated electric angle θ by the first estimation method １ and estimated rotational speed N １ To obtain this, regardless of whether the output of a vehicle approach warning sound is required, the final voltage command v ｄｑ ＊ The additional high-frequency voltage command v ｄｑｈ ＊ It must include N. Ｂ If ≤ N, and no vehicle approach warning sound output is required, the final voltage command v ｄｑ ＊ The additional high-frequency voltage command v ｄｑｈ ＊ It is not necessary to include it. Furthermore, the vehicle approach warning sound is usually required to be emitted when the vehicle speed is low and the rotational speed N is small.

[0117] Therefore, in this embodiment, the predetermined rotational speed N Ｂ The rotational speed is set to a rotational speed corresponding to the upper limit of the vehicle speed at which a vehicle approach warning sound needs to be emitted. In other words, in this embodiment, the rotational speed is set to a predetermined rotational speed N such that the timing at which the output of the vehicle approach warning sound becomes unnecessary coincides with the timing at which the rotational state estimation method completely switches from the first estimation method to the second estimation method. Ｂ It is stipulated that...

[0118] Therefore, when the output of the vehicle approach warning sound is no longer required, the basic voltage command v ｄｑ１ ＊,v ｄｑ２ ＊ Additional voltage command v ｄｑｈ ＊ The addition is stopped, and at the same time, the method for estimating the rotation state is completely switched from the first estimation method to the second estimation method.

[0119] In this embodiment, the final estimated value calculation unit 48 calculates the predetermined rotational speed N as described above. Ａ , N Ｂ The system uses these two thresholds to determine whether to switch between the first and second estimation methods, but the final estimated value calculation unit 48 may be configured more simply. For example, the final estimated value calculation unit 48 may have N < N Ｂ When this is the case, the θ of the first estimation method １ and N １ The final electrical angle θ and rotational speed N are output, and N Ｂ When N ≤ θ, the θ of the second estimation method ２ and N ２ It may be configured to output the final electrical angle θ and rotational speed N.

[0120] Figure 4 is a block diagram showing the configuration of the sound control unit 37. As shown in Figure 4, the sound control unit 37 includes an additional voltage command setting unit 51 and a speaker playback control unit 52.

[0121] The additional voltage command setting unit 51 sets the additional voltage command v ｄｑｈ ＊ The specific frequency ω ｈ The target frequency f ｓ ＊ Set according to the instructions.

[0122] In this embodiment, if output of a vehicle approach warning sound is required, the additional voltage command setting unit 51 sets a specific frequency ω ｈ The frequency f of the first tone that constitutes the vehicle approach warning sound １ The corresponding frequency (ω １ Set it to ).

[0123] Furthermore, if the output of a vehicle approach warning sound is not required, the additional voltage command setting unit 51 will set a specific frequency ω ｈ a predetermined frequency ω ０ Set to the predetermined frequency ω０ This is a frequency suitable for estimating the rotational state using the first estimation method, and is predetermined by fitting based on experiments or simulations.

[0124] The additional voltage command setting unit 51 sets the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The target sound pressure level P ｓ ＊ This is set according to the target torque.

[0125] The additional voltage command setting unit 51 sets a parameter representing the target torque, for example, the torque command T ＊ or q-axis current command i ｑ ＊ This can be used. In this embodiment, the additional voltage command setting unit 51 uses the q-axis current command i as a parameter representing the target torque. ｑ ＊ This is used. And, if the output of a vehicle approach warning sound is required, the additional voltage command setting unit 51 shall, in principle, set the amplitude V ｈ The target sound pressure level P ｓ ＊ Based on this, a predetermined amplitude V corresponding to the sound pressure level required for the first tone that constitutes the vehicle approach warning sound. １ Set to the following. However, the additional voltage command setting unit 51 sets the q-axis current command i ｑ ＊ The amplitude V corresponds to the amplitude V. ｈ This changes the q-axis current command i. Specifically, the additional voltage command setting unit 51 changes the q-axis current command i. ｑ ＊ The amplitude V increases as the (target torque) increases. ｈ Reduce the q-axis current command i ｑ ＊ The amplitude V decreases as the (target torque) decreases. ｈ Make it bigger.

[0126] If the output of a vehicle proximity warning sound is not required, the additional voltage command setting unit 51 sets the amplitude V ｈ a predetermined amplitude V ０ Set to the predetermined amplitude V. ０ This is an amplitude suitable for estimating the rotational state by the first estimation method, and is predetermined by fitting based on experiments or simulations.

[0127] In addition, the additional voltage command setting unit 51 sets the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ The input determines whether sound output is requested. In this embodiment, when a vehicle approach warning sound needs to be emitted, the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ When this is input, the additional voltage command setting unit 51 determines that sound output is requested.

[0128] Furthermore, the additional voltage command setting unit 51 sets the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ The system determines whether the sound specified by the system can be realized using the magnetostrictive sound of the electric motor 12. The sound pressure level and frequency that can be realized with magnetostrictive sound are determined by the structure of the electric motor 12, etc. Therefore, the range of sound pressure levels and frequencies that can be realized with magnetostrictive sound is usually known through experimentation or simulation. In this embodiment, as described above, the first sound that constitutes the vehicle approach warning sound can be realized using magnetostrictive sound, while the second sound cannot be realized using magnetostrictive sound.

[0129] Furthermore, the additional voltage command setting unit 51 sets the magnetostrictive sound implementation flag FLG. The magnetostrictive sound implementation flag FLG is set to the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ This flag identifies which sounds from the one or more sounds specified by the system are to be output as magnetostrictive sounds and which are not. The magnetostrictive sound implementation flag FLG is input to the speaker playback control unit 52.

[0130] The speaker playback control unit 52 sets the target sound pressure level P based on the magnetostrictive sound implementation flag FLG. ｓ ＊ and target frequency f ｓ ＊The system identifies which sounds are not output as magnetostrictive tones from among the sounds specified by the system. The speaker playback control unit 52 then plays (outputs) these sounds that are not output as magnetostrictive tones using the speaker 13. In this embodiment, the speaker playback control unit 52 plays the second sound that constitutes the vehicle approach warning sound.

[0131] As described above, the electric vehicle 100 of this embodiment generates a target sound, which is a vehicle approach notification sound, from the electric motor 12. To this end, the controller 14 generates a basic voltage command v in the voltage command generation unit 32. ｄｑ１ ＊ ,v ｄｑ２ ＊ The additional voltage command setting unit 54 calculates a specific frequency ω corresponding to the vehicle approach warning sound. ｈ Additional voltage command v ｄｑｈ ＊ The basic voltage command v is calculated and the final voltage command generation unit 43 generates the basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ Additional voltage command v ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The controller 14 calculates this final voltage command v via the PWM control unit 34. ｄｑ ＊ The dq axis voltage v according to ｄｑ The inverter 11 is switched so that the torque command T is applied. As a result, the motor 12 receives the torque command T. ＊ While outputting torque T (target torque) corresponding to the motor 12, it generates a target sound, a vehicle approach warning sound, using magnetostrictive noise. The additional voltage command setting unit 54 sets the additional voltage command v as the target torque of the motor 12 increases. ｄｑｈ ＊ Amplitude V ｈ As the target torque decreases, the amplitude V decreases. ｈ Increase the additional voltage command v. ｄｑｈ ＊ Amplitude V ｈ The reason for changing it according to the target torque is as follows:

[0132] Figure 5 shows the d-axis inductance L.ｄ and q-axis inductance L ｑ This graph schematically shows the characteristics. In Figure 5, the d-axis inductance L ｄ The dashed line indicates the q-axis inductance L. ｑ This is shown by a solid line. Figure 6 is an explanatory diagram showing the current flowing through the electric motor 12. In Figure 6, the graph 56 represented by the thick solid line is the dq axis current i due to MTPA control. ｄｑ This represents the operating point P. ０ Torque command T ＊ The operating point is where the value is zero, and graph 57 shows the operating point P. ０ At a constant amplitude V ｈ (For example, V ｈ = V １ ) Additional voltage command v ｄｑｈ ＊ The dq-axis current i when superimposed ｄｑ This shows the operating point P. １ Torque command T ＊ For example, the operating point is 100 Nm, and Graph 58 shows the operating point P. １ At a constant amplitude V ｈ (For example, V ｈ = V １ ) Additional voltage command v ｄｑｈ ＊ The dq-axis current i when superimposed ｄｑ It represents.

[0133] As shown in Figure 5, in the electric motor 12 of this embodiment, the d-axis inductance L ｄ is the q-axis current command i ｑ ＊ It is generally constant, regardless of the (target torque). On the other hand, the q-axis inductance L ｑ is the q-axis current command i ｑ ＊ As the (target torque) increases, the d-axis inductance L decreases. ｄ It approaches the value of .

[0134] Therefore, in order to realize the vehicle approach warning sound using magnetostrictive sound, simply the target sound pressure level P ｓ ＊ A constant amplitude V corresponding to the amplitude V ｈ Additional voltage command v ｄｑｈ ＊Using this, the q-axis current command i ｑ ＊ When the (target torque) increases, the q-axis inductance L ｑ Due to the decrease, the dq axis current i ｄｑ The amplitude increases. Specifically, as shown in Figure 6, for example, if the operating point is P ０ From P １ When it changes, the dq axis current i ｄｑ The circle or ellipse representing the result becomes larger. As a result, a constant amplitude V ｈ Despite providing the necessary parameters, the sound pressure level of the magnetostrictive sound unintentionally increases.

[0135] Also, target sound pressure level P ｓ ＊ A constant amplitude V corresponding to the amplitude V ｈ Additional voltage command v ｄｑｈ ＊ When using, the q-axis current command i ｑ ＊ As the (target torque) decreases, the q-axis inductance L ｑ Due to the increase, the dq axis current i ｄｑ The amplitude becomes smaller. Specifically, as shown in Figure 6, for example, the operating point is P １ From P ０ When it changes, the dq axis current i ｄｑ The circle or ellipse representing becomes smaller. As a result, a constant amplitude V ｈ Despite providing the necessary parameters, the sound pressure level of the magnetostrictive sound unintentionally decreases.

[0136] Therefore, in this embodiment, the additional voltage command setting unit 54 sets the additional voltage command v as the target torque of the electric motor 12 increases. ｄｑｈ ＊ Amplitude V ｈ As the target torque decreases, the amplitude V decreases. ｈ This increases the q-axis current command i. ｑ ＊ Even if the (target torque) changes, the dq axis current i ｄｑ The size of the circle or ellipse representing the target remains constant, and as a result, the sound pressure level of the magnetostrictive sound reaches the target sound pressure level P. ｓ ＊ A constant sound pressure level P corresponding to the sound pressure level P ｓIt is maintained.

[0137] Figure 7 is a flowchart relating to the motor control of this embodiment. As shown in Figure 7, in step S10, the controller 14 issues a torque command T ＊ The target sound pressure level P of the sound that the electric vehicle 100 should output. ｓ ＊ and target frequency f ｓ ＊ Obtain it.

[0138] In step S11, the first basic voltage command generation unit 41 generates a first basic voltage command v for current vector control. ｄｑ１ ＊ The second basic voltage command generation unit 42 calculates and generates a second basic voltage command v for voltage phase control. ｄｑ２ ＊ Perform the calculation.

[0139] In step S12, the additional voltage command setting unit 51 sets the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ The presence or absence of input determines whether a sound request is made, i.e., whether the output of a vehicle approach warning sound is required.

[0140] In step S13, the additional voltage command setting unit 51 sets the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ It is determined whether the sound specified by can be realized using the magnetostrictive sound of the electric motor 12.

[0141] Furthermore, the output of a vehicle approach warning sound is required (Step S12: YES), and the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ If the sound specified can be realized with the magnetostrictive sound of the electric motor 12 (step S13: YES), proceed to step S14.

[0142] Then, in step S14, the additional voltage command setting unit 51 sets the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The target sound pressure level Pｓ ＊ A predetermined amplitude V corresponding to the amplitude V １ Centered around the q-axis current command i ｑ ＊ The value is set according to the (target torque). In addition, the additional voltage command setting unit 51 sets the additional voltage command v ｄｑｈ ＊ The specific frequency ω ｈ The target frequency f ｓ ＊ The corresponding frequency (ω １ ) is set to that. In other words, in step S14, the additional voltage command setting unit 51 sets the amplitude V ｈ and specific frequency ω ｈ This is set to a value that outputs the first tone, which constitutes the vehicle approach warning sound using magnetostrictive sound.

[0143] On the other hand, if the output of a vehicle approach warning sound is not required (step S12: NO), or if the target sound pressure level P ｓ ＊ and target frequency f ｓ ＊ If the sound specified cannot be achieved with the magnetostrictive noise of the electric motor 12 (step S13: NO), proceed to step S15.

[0144] Then, in step S15, the additional voltage command setting unit 51 sets the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ A predetermined amplitude V suitable for estimating the rotation state by the first estimation method. ０ Set to the additional voltage command v. ｄｑｈ ＊ The specific frequency ω ｈ A predetermined frequency ω suitable for estimating the rotation state by the first estimation method. ０ Set to the amplitude V. In other words, in step S15, the additional voltage command setting unit 51 sets the amplitude V. ｈ and specific frequency ω ｈ This is set to a value suitable for estimating the rotation state using the first estimation method.

[0145] In step S16, the final estimated value calculation unit 48 calculates the rotational speed N to a predetermined rotational speed N. Ａ , N ＢBy comparing this with the previous method, the method for estimating the rotation state is switched.

[0146] Then, in step S16, N < N Ｂ And high frequency (additional voltage command v ｄｑｈ ＊ When estimating the rotation state using the first estimation method which uses ), proceed to step S17.

[0147] In step S17, the final voltage command generation unit 43 generates the control mode selection signal M ｓｗ The first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ Select one of the following, and add a high-frequency additional voltage command to the selected base voltage command v ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The following is calculated. Here, as a typical example, the final voltage command generation unit 43 generates the first basic voltage command v ｄｑ１ ＊ Additional voltage command v ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The calculation will be performed.

[0148] Then, in step S18, the speaker playback control unit 52 plays the second sound that constitutes the vehicle approach warning sound.

[0149] Then, the process proceeds to step S20, where the PWM control unit 34 issues the final voltage command v ｄｑ ＊ By switching the inverter 11 accordingly, the electric motor 12 is driven, and the electric motor 12 outputs torque T while generating a magnetostrictive sound corresponding to the first tone. As a result, the electric vehicle 100 runs while emitting a vehicle approach warning sound consisting of magnetostrictive sound and regenerated sound.

[0150] On the other hand, in step S16, N Ｂ ≤ N, and high frequency (additional voltage command v ｄｑｈ ＊When estimating the rotation state using a second estimation method that does not use ( ), proceed to step S19.

[0151] In step S19, the final voltage command generation unit 43 generates the control mode selection signal M ｓｗ The first basic voltage command v ｄｑ１ ＊ or second basic voltage command v ｄｑ２ ＊ Select one of the following, and add a high-frequency additional voltage command to the selected base voltage command v ｄｑｈ ＊ Without adding anything, the selected base voltage command is used directly as the final voltage command v ｄｑ ＊ It outputs as follows. Here, as a typical example, the final voltage command generation unit 43 generates the second basic voltage command v ｄｑ２ ＊ The final voltage command v ｄｑ ＊ It should be output as follows.

[0152] Then, the process proceeds to step S20, where the PWM control unit 34 issues the final voltage command v ｄｑ ＊ By switching the inverter 11 accordingly, the electric motor 12 is driven, and the electric motor 12 outputs torque T. In other words, the electric vehicle 100 does not emit a vehicle approach warning sound and simply moves.

[0153] In step S21, the final voltage command generation unit 43 determines whether regenerative control is being performed. In step S22, the final voltage command generation unit 43 determines, for example, based on the magnitude of the rotational speed N, whether the electric vehicle 100 can be said to have come to a substantially stopped state.

[0154] If it is determined in step S21 that regenerative control is not being performed, or if it is determined in step S22 that the electric vehicle 100 is not in a state to be stopped even if regenerative control is being performed, then steps S23 and S24 are skipped, and the control from step S10 to step S20 is repeated.

[0155] On the other hand, if regenerative control is being performed and it is determined that the electric vehicle 100 has come to a complete stop, the process proceeds to step S23. In step S23, the basic voltage command is changed to an additional voltage command v ｄｑｈ ＊ Even if the addition was performed, the final voltage command generation unit 43 generates an additional voltage command v ｄｑｈ ＊ The addition is stopped. Therefore, the final voltage command generation unit 43 essentially generates the first basic voltage command v ｄｑ１ ＊ The final voltage command v ｄｑ ＊ It outputs as follows. However, in this situation, the first basic voltage command v ｄｑ１ ＊ and final voltage command v ｄｑ ＊ The value is almost zero. Also, in step S24, if the second sound that constitutes the vehicle approach warning sound was being played, the speaker playback control unit 52 stops it. Therefore, when the electric vehicle 100 stops, the vehicle approach warning sound also stops.

[0156] Figure 8 shows the sound pressure level P of magnetostrictive sound in the comparative example. ｓ This graph schematically shows the changes, etc. The comparative example is the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The q-axis current command i ｑ ＊ Without changing it accordingly, the target sound pressure level P of the first sound of the vehicle approach warning sound ｓ ＊ A constant amplitude V corresponding to the amplitude V １ This is an example of setting it to [this value].

[0157] Figure 8(A) shows time t １ From time t ２ Torque command T in the scene where the electric vehicle 100 accelerates ＊ The (target torque) changes over time. Here, it is assumed that the electric vehicle 100 is traveling at a relatively low speed and needs to emit a vehicle approach warning sound. Also, the electric motor 12 is controlled by the first basic voltage command v ｄｑ１ ＊ Additional voltage command v ｄｑｈ ＊ The final voltage command v after adding the following: ｄｑ＊ It is controlled according to this, and the rotational state is estimated by the first estimation method.

[0158] FIG. 8(B) shows the transition of the d-axis current i ｄ . In FIG. 8(B), the d-axis current command i ｄ is indicated by a broken line as a reference for the average d-axis current i ｄ ＊ . Also, in FIG. 8(B), the amplitude of the d-axis current i ｄ is indicated by the dotted envelope line. FIG. 8(C) shows the transition of the q-axis current i ｑ . In FIG. 8(C), the q-axis current command i ｑ is indicated by a broken line as a reference for the average q-axis current i ｑ ＊ . Also, in FIG. 8(C), the amplitude of the q-axis current i ｑ is indicated by the dotted envelope line.

[0159] FIG. 8(D) shows the transition of the specific frequency ω ｄｑｈ ＊ which is the frequency of the additional voltage command v ｈ . FIG. 8(E) shows the transition of the amplitude V ｄｑｈ ＊ of the additional voltage command v ｈ . And FIG. 8(F) shows the sound pressure level P ｓ of the magnetostrictive noise generated by the motor 12 by a solid line, and shows the target sound pressure level P ｓ ＊ of this magnetostrictive noise by a broken line.

[0160] As shown in FIG. 8(A), here, the electric vehicle 100 accelerates from time t １ to time t ２ , and it is assumed that the torque command T ＊ (target torque) increases. In this case, as shown in FIG. 8(B), overall, the d-axis current i ｄ decreases in response to the increase in the torque command T ＊ . Also, as shown in FIG. 8(C), overall, the q-axis current i ｑ increases in response to the increase in the torque command T ＊ .

[0161] In this comparative example, in order to output the first sound of the vehicle approach warning sound using magnetostrictive sound, as shown in Figures 8(D) and 8(E), the torque command T ＊ Regardless of size, always ω ｈ = ω １ and V ｈ = V １ The additional voltage command v set to ｄｑｈ ＊ Therefore, as shown in Figures 8(B) and 8(C), the torque command T ＊ When it rises, an additional voltage command v ｄｑｈ ＊ The superposition of i results in the d-axis current i ｄ and q-axis current i ｑ The amplitude of the fluctuations that occur increases. As a result, as shown in Figure 8(F), the sound pressure level P of the magnetostrictive sound ｓ The target sound pressure level P ｓ ＊ Unable to maintain, torque command T ＊ It increases in proportion to the rise of the additional voltage command v. ｄｑｈ ＊ Amplitude V ｈ This simply refers to the target sound pressure level P ｓ ＊ A constant value (V) corresponding to １ Controlling it to that extent changes how the magnetostrictive sound is actually perceived.

[0162] Figure 9 shows the sound pressure level P of the magnetostrictive sound in this embodiment. ｓ This graph schematically illustrates the above. In this embodiment, as described above, the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The q-axis current command i ｑ ＊ This is an example of how to change the parameters accordingly. The parameters shown in Figures 9(A) to 9(F) are the same as those in the comparative example (Figure 8) mentioned above.

[0163] As shown in Figure 9(A), here the electric vehicle 100 is at time t １ From time t ２ Accelerates towards the torque command T ＊ The (target torque) increases. As a result, as shown in Figure 9(B), the d-axis current i ｄTorque command T ＊ It decreases in proportion to the increase in . Also, as shown in Figure 9(C), overall, the q-axis current i ｑ Torque command T ＊ It increases in accordance with the rise in [the relevant factor]. These overall changes are similar to those in the comparative example described above.

[0164] Furthermore, as shown in Figure 9(D), in this embodiment as well, in order to output the first sound of the vehicle approach warning sound using magnetostrictive sound, a specific frequency ω ｈ (ω) ｈ = ω １ ) is set to ). However, as shown in Figure 9(E), in this embodiment, the amplitude V ｈ The target sound pressure level P ｓ ＊ A predetermined amplitude V corresponding to the amplitude V １ While using as a standard, the torque command T ＊ It is adjusted accordingly. Here, the torque command T ＊ As the amplitude V increases, ｈ This is reduced accordingly. Therefore, as shown in Figures 9(B) and 9(C), the torque command T ＊ Even if it rises, the additional voltage command v ｄｑｈ ＊ The superposition of i results in the d-axis current i ｄ and q-axis current i ｑ The amplitude of the fluctuations that occur is generally constant. As a result, as shown in Figure 9(F), the sound pressure level P of the magnetostrictive sound ｓ The target sound pressure level P ｓ ＊ This can be maintained. That is, the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The target torque (torque command T ＊ By adjusting it accordingly, the actual way magnetostrictive tones are perceived can be maintained to the way they were originally intended.

[0165] Figure 10 shows the sound pressure level P of the magnetostrictive sound in this embodiment. ｓ This graph schematically illustrates the above.

[0166] Figure 10(A) shows an electric vehicle 100 that is decelerating by regenerative braking, at time t ３ From time t ４The torque command T in a scene where the regenerative braking force is weakened and the vehicle stops gently and smoothly ＊ shows the transition of (target torque). FIG. 10(B) shows the transition of the rotational speed N in this scene. Here, it is assumed that the electric vehicle 100 is decelerated to such an extent that it is necessary to emit a vehicle approach notification sound and is traveling at a relatively low speed. Also, the electric motor 12 is controlled according to the final voltage command v ｄｑ１ ＊ obtained by adding the additional voltage command v ｄｑｈ ＊ to the first basic voltage command v, and the rotational state is estimated by the first estimation method. ＊

[0167] FIG. 10(C) shows the transition of the d-axis current id. In FIG. 10(C), the d-axis current command i ｄ is indicated by a broken line as a guide for the average d-axis current i ｄ ＊ . Also, in FIG. 10(C), the amplitude of the d-axis current i ｄ is indicated by the dotted envelope line. FIG. 10(D) shows the transition of the q-axis current i ｑ . In FIG. 10(D), the q-axis current command i ｑ is indicated by a broken line as a guide for the average q-axis current i ｑ ＊ . Also, in FIG. 10(D), the amplitude of the q-axis current i ｑ is indicated by the dotted envelope line.

[0168] FIG. 10(E) shows the transition of the specific frequency ω ｄｑｈ ＊ which is the frequency of the additional voltage command v ｈ . FIG. 10(F) shows the transition of the amplitude V ｄｑｈ ＊ of the additional voltage command v ｈ . And FIG. 10(G) shows the sound pressure level P ｓ of the magnetostrictive noise generated by the electric motor 12 by a solid line, and shows the target sound pressure level P ｓ of this magnetostrictive noise by a broken line ＊ ３ .

[0169] As shown in FIG. 10(A), here, the electric vehicle 100 decelerated by regenerative braking is from time t ３ to time t４ In order to come to a gradual stop over time t ３ Torque command T ＊ (Target torque) maintains a constant negative value, at time t ３ From time t ４ Torque command T ＊ Assume that approaches zero asymptotically. As a result, as shown in Figure 10(B), the rotational speed N decreases smoothly and gradually, at time t ４ It becomes zero at time t. In other words, the electric vehicle 100 is at time t ４ It stops there.

[0170] At this time, as shown in Figure 10(C), the d-axis current i ｄ Overall, at time t ３ It maintains a generally constant negative value until time t ４ It becomes zero. Also, as shown in Figure 10(D), the q-axis current i ｑ Also, overall, time t ３ It maintains a generally constant negative value until time t ４ It becomes zero.

[0171] Furthermore, as shown in Figure 10(E), while the electric vehicle 100 is in motion, the first sound of the vehicle approach warning sound is output using magnetostrictive sound, with a specific frequency ω ｈ (ω) ｈ = ω １ ) is set to ). However, as shown in Figure 10(F), the amplitude V ｈ The target sound pressure level P ｓ ＊ A predetermined amplitude V corresponding to the amplitude V １ While using as a standard, the torque command T ＊ It is adjusted accordingly. Here, the torque command T ＊ Since the magnitude decreases, the amplitude V ｈ This is increased accordingly.

[0172] Therefore, as shown in Figures 10(C) and 10(D), the torque command T ＊ Even if the magnitude decreases, the additional voltage command v ｄｑｈ ＊ The superposition of i results in the d-axis current i ｄ and q-axis current i ｑThe amplitude of the fluctuations that occur is generally constant. As a result, as shown in Figure 10(G), the sound pressure level P of the magnetostrictive sound remains constant while the electric vehicle 100 is running. ｓ The target sound pressure level P ｓ ＊ This can be maintained. That is, the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ The target torque (torque command T ＊ By changing it accordingly, even when the electric vehicle 100 decelerates and stops, the actual sound of magnetostrictive noise can be maintained at the originally intended level.

[0173] Furthermore, as shown in Figures 10(E) and 10(F), time t ４ When the electric vehicle 100 stops, the amplitude V ｈ and specific frequency ω ｈ The value becomes zero, and the additional voltage command v ｄｑｈ ＊ The superposition is stopped. Therefore, as shown in Figure 10(G), when the electric vehicle 100 stops, the vehicle approach warning sound is also stopped.

[0174] [Second Embodiment] In the electric vehicle 100 of the first embodiment described above, sensorless control is performed to estimate the rotational position of the electric motor 12 without using a rotation detector, but the invention is not limited to this. The control of the first embodiment described above can also be applied when the rotational position of the electric motor 12 is detected using a rotation detector.

[0175] Figure 11 is a block diagram showing the schematic configuration of the electric vehicle 200 according to the second embodiment. As shown in Figure 11, the electric vehicle 200 according to the second embodiment includes a rotation detector 201 and a rotation state detection unit 202 instead of the rotation state estimation unit 36 ​​of the first embodiment.

[0176] The rotation detector 201 is installed on the electric motor 12 and outputs a signal corresponding to the rotational position of the electric motor 12. The rotation detector 201 is composed of, for example, an encoder or a resolver.

[0177] The rotation state detection unit 202 detects (calculates) the electrical angle θ, electrical angular velocity ω, and rotation speed N based on the output signal of the rotation detector 201. The detected electrical angle θ is used in the coordinate transformations in the coordinate transformation units 33 and 35, as in the first embodiment. In this embodiment, the detected rotation speed N is used in the current command generation unit 31 and the voltage command generation unit 32.

[0178] Furthermore, when the rotation state of the electric motor 12 is detected by the rotation detector 201 and the rotation state detection unit 202, an additional voltage command v is issued for estimating the rotation state. ｄｑｈ ＊ There is no need to superimpose it. Therefore, in this embodiment, the additional voltage command v ｄｑｈ ＊ The basic voltage command v is used solely to generate magnetostrictive noise. ｄｑ１ ＊ ,v ｄｑ２ ＊ It is superimposed on. Therefore, in the first embodiment, the additional voltage command setting unit 51 of the sound control unit 37 sets the amplitude V for estimating the rotation state by the first estimation method. ｈ and specific frequency ω ｈ In some cases, an amplitude V may be set, but in this embodiment, ｈ and specific frequency ω ｈ No such settings are made. Other configurations and functions are the same as in the first embodiment.

[0179] Figure 12 is a flowchart relating to motor control in the second embodiment. In this embodiment, as described above, when it is necessary to output a vehicle approach warning sound, an additional voltage command v ｄｑｈ ＊ This is used. For this reason, as shown in Figure 12, step S15 in the first embodiment is omitted. That is, if it is determined in step S12 that output of a vehicle approach warning sound is unnecessary, or if the target sound pressure level P is set in step S13, ｓ ＊ and target frequency f ｓ ＊ If it is determined that the sound specified by the device cannot be achieved by the magnetostrictive noise of the electric motor 12, the process proceeds to step S19.

[0180] Otherwise, it is the same as the first embodiment. Therefore, when it is necessary to output a vehicle approach warning sound and this can be realized with magnetostrictive sound, an additional voltage command v ｄｑｈ ＊ The control mode selection signal M is set. ｓｗ A high-frequency additional voltage command v is added to the basic voltage command selected accordingly. ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The calculation is performed.

[0181] In this embodiment as well, in step S14, an additional voltage command v ｄｑｈ ＊ Amplitude V ｈ is the q-axis current command i ｑ ＊ It is adjusted according to the (target torque). Therefore, in this embodiment as well, the sound pressure level P of the magnetostrictive sound that constitutes the vehicle approach warning sound is also adjusted. ｓ The target sound pressure level P ｓ ＊ This is maintained, resulting in a consistent, predetermined level of audibility.

[0182] In the first and second embodiments described above, one sound constituting the vehicle approach warning sound is generated by magnetostrictive sound, but for example, multiple types of additional voltage commands v ｄｑｈ ＊ By configuring this setting, it is also possible to generate multiple magnetostrictive tones. Therefore, all the sounds that make up the vehicle approach warning sound may be emitted using magnetostrictive tones.

[0183] Furthermore, while the first and second embodiments described above illustrate examples in which the electric vehicles 100 and 200 emit a vehicle approach warning sound, the electric vehicles 100 and 200 can generate all or part of sounds other than the vehicle approach warning sound, such as sounds intended for the driver, using magnetostrictive sound.

[0184] As described above, the electric vehicle control methods according to the first and second embodiments are electric vehicle control methods that generate a predetermined target sound (for example, a vehicle approach warning sound) from the electric motor 12 used to drive the electric vehicles 100 and 200. Specifically, in this control method, the target torque (T) that the electric motor 12 should output is determined.＊ or i ｑ ＊ ) A basic voltage command v that determines the voltage applied to the electric motor 12 in accordance with ｄｑ１ ＊ ,v ｄｑ２ ＊ It calculates a specific frequency ω corresponding to the target sound. ｈ Additional voltage command v ｄｑｈ ＊ Set the basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ Additional voltage command v ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The final voltage command v is calculated and sent to the motor 12. ｄｑ ＊ By applying a voltage according to the specified parameters, the motor 12 is made to output the target torque while simultaneously generating the target sound from the motor 12. Furthermore, the additional voltage command v increases as the target torque increases. ｄｑｈ ＊ Amplitude V ｈ The value is reduced, and the smaller the target torque, the greater the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ Make it bigger.

[0185] In this way, when generating target sounds such as vehicle approach warning sounds using magnetostrictive noise generated from the electric motor 12, an additional voltage command v is superimposed to generate the magnetostrictive noise. ｄｑｈ ＊ Amplitude V ｈ If this is changed according to the target torque, the sound pressure level P of the target sound will remain the same even if the target torque changes. ｓ This allows the frequency to be kept relatively constant. Therefore, the perception of the target sound can be maintained at the intended level.

[0186] In the electric vehicle control method according to the first and second embodiments described above, the specific frequency ω ｈ The basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ This frequency is higher than the fundamental frequency ω, which is the frequency of ω.

[0187] Thus, a specific frequency ω ｈ By setting the frequency higher than the fundamental frequency ω, a high-frequency additional voltage command v is generated. ｄｑｈ ＊ By using this method, it is possible to generate a magnetostrictive sound that matches the target sound with almost no effect on the torque control of the electric motor 12. In other words, it is easy to achieve both control of the torque T of the electric motor 12 and control of the magnetostrictive sound.

[0188] In the electric vehicle control method according to the first and second embodiments described above, the specific frequency ω ｈ The frequency is set to an integer multiple of the fundamental frequency ω, and the additional voltage command v ｄｑｈ ＊ The basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ It is composed of harmonics.

[0189] Thus, the additional voltage command v ｄｑｈ ＊ If we define this as a harmonic, the types (frequencies) of magnetostrictive noise that can be generated by the motor 12 may be somewhat limited. However, since harmonics are normally included in torque control, it is particularly easy to generate magnetostrictive noise that matches the target sound without affecting the torque control of the motor 12. In other words, it is particularly easy to achieve both torque T control of the motor 12 and magnetostrictive noise control.

[0190] In the control method for an electric vehicle according to the first embodiment described above, an additional voltage command v ｄｑｈ ＊ Response current (i ｄｑｈ Based on this, the rotational state of the electric motor 12 is estimated.

[0191] Thus, the additional voltage command v ｄｑｈ ＊ This can be used not only to generate magnetostrictive noise, but also to estimate the rotational state of the electric motor 12. And the additional voltage command v ｄｑｈ ＊ Response current (i ｄｑｈIf the rotation state of the electric motor 12 is estimated based on the above, the rotation detector 201 can be omitted as in the first embodiment. Also, when high frequency (harmonics) etc. are used to estimate the rotation state of the electric motor 12, the magnetostrictive noise generated is usually considered noise. However, as described above, an additional voltage command v adjusted to generate the desired magnetostrictive noise is used. ｄｑｈ ＊ By using this to estimate the rotational state, magnetostrictive noise can be actively and effectively utilized. Therefore, the control according to the above embodiment is particularly suitable when the electric motor 12 is controlled without sensors.

[0192] In the control method for an electric vehicle according to the first embodiment described above, an additional voltage command v ｄｑｈ ＊ Response current (i ｄｑｈ The rotation state of the electric motor 12 is estimated by a first estimation method based on ) or by a second estimation method using a magnetic flux observer. When the output of a target sound (e.g., a vehicle approach warning sound) is required, the rotation state is estimated by the first estimation method, and when the output of the target sound is no longer required, the basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ Additional voltage command v ｄｑｈ ＊ The addition is stopped, and the method for estimating the rotation state is switched from the first estimation method to the second estimation method.

[0193] Thus, if the timing at which the output of the target sound (vehicle approach warning sound) becomes unnecessary coincides with the timing at which the rotation state estimation method switches from the first estimation method to the second estimation method, an additional voltage command v is issued solely for the purpose of estimating the rotation state. ｄｑｈ ＊ This eliminates the need for superimposition. As a result, the magnetostrictive noise generated by the electric vehicle 100 is fully utilized without becoming noise.

[0194] In the electric vehicle control methods according to the first and second embodiments described above, when the electric vehicles 100 and 200 stop, the basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊Additional voltage command v ｄｑｈ ＊ Stop adding.

[0195] Thus, when the electric vehicles 100 and 200 are effectively stopped, an additional voltage command v ｄｑｈ ＊ When the superposition is stopped (canceled), the generation of magnetostrictive noise also stops. When the electric vehicles 100 and 200 are stopped, it is usually unnecessary to emit vehicle approach warning sounds, etc. Therefore, an additional voltage command v is issued in response to the determination that the electric vehicles 100 and 200 have stopped. ｄｑｈ ＊ Stopping the superposition prevents the continuous generation of unnecessary magnetostrictive noise. It also reduces unnecessary energy consumption.

[0196] In the electric vehicle control methods according to the first and second embodiments described above, the target sound is all or part of the vehicle approach notification sound.

[0197] Thus, in the first and second embodiments, the target sound realized by magnetostrictive sound is specifically a vehicle proximity warning sound. A vehicle proximity warning sound is a typical example of a sound actively emitted by electric vehicles 100 and 200. Therefore, as described above, it is preferable to use a vehicle proximity warning sound as the target sound and realize it by magnetostrictive sound.

[0198] In the electric vehicle control methods according to the first and second embodiments described above, the target sound is a part of the vehicle approach notification sound (first sound), and the vehicle approach notification sound consists of a target sound (first sound) output by the electric motor 12 and a sound reproduced by the speaker 13 (second sound).

[0199] In this way, by outputting the sounds emitted by the electric vehicles 100 and 200 from two separate sound sources, the electric motor 12 and the speaker 13, the configuration for outputting the reproduced sound can be simplified, such as by reducing the amount of pre-prepared sound data. Furthermore, by separating the sound sources that output sounds of different frequencies, it is easier to prevent frequency interference compared to outputting them from a single sound source. Therefore, the sounds that the electric vehicles 100 and 200 are supposed to emit can be heard clearly and as intended.

[0200] The control devices for electric vehicles according to the first and second embodiments described above are electric vehicle control devices (controllers 14) that generate a predetermined target sound (for example, a vehicle approach warning sound) from the electric motor 12 used to drive the electric vehicles 100 and 200. This control device (14) determines the target torque (T) that the electric motor 12 should output. ＊ or i ｑ ＊ ) A basic voltage command v that determines the voltage applied to the electric motor 12 in accordance with ｄｑ１ ＊ ,v ｄｑ２ ＊ A basic voltage command calculation unit (41, 42) that calculates a specific frequency ω corresponding to the target sound, and ｈ Additional voltage command v ｄｑｈ ＊ The additional voltage command setting unit 51 sets the basic voltage command v ｄｑ１ ＊ ,v ｄｑ２ ＊ Additional voltage command v ｄｑｈ ＊ By adding this, the final voltage command v ｄｑ ＊ The final voltage command generation unit 43 calculates the final voltage command v and the motor 12 receives the final voltage command v ｄｑ ＊ The system includes a PWM control unit 34 that generates a target sound from the motor 12 while simultaneously causing the motor 12 to output a target torque by applying a voltage according to the target torque. The additional voltage command setting unit 51 sets an additional voltage command v as the target torque increases. ｄｑｈ ＊ Amplitude V ｈ The value is reduced, and the smaller the target torque, the greater the additional voltage command v ｄｑｈ ＊ Amplitude V ｈ It is configured to be larger.

[0201] In this way, when generating target sounds such as vehicle approach warning sounds using magnetostrictive noise generated from the electric motor 12, an additional voltage command v is superimposed to generate the magnetostrictive noise. ｄｑｈ ＊ Amplitude V ｈ If this is changed according to the target torque, the sound pressure level P of the target sound will remain the same even if the target torque changes. ｓThis allows the frequency to be kept relatively constant. Therefore, the perception of the target sound can be maintained at the intended level.

[0202] Although embodiments and modifications of the present invention have been described above, the configurations described in the above embodiments and modifications represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A control method for an electric vehicle that generates a predetermined target sound from an electric motor used to drive the electric vehicle, comprising: calculating a basic voltage command that determines the voltage to be applied to the electric motor according to a target torque that the electric motor should output; setting an additional voltage command having a specific frequency corresponding to the target sound; calculating a final voltage command by adding the additional voltage command to the basic voltage command; applying a voltage to the electric motor according to the final voltage command so that the electric motor outputs the target torque while generating the target sound from the electric motor; decreasing the amplitude of the additional voltage command as the target torque increases, and increasing the amplitude of the additional voltage command as the target torque decreases.

2. A method for controlling an electric vehicle according to claim 1, wherein the specific frequency is a frequency higher than the fundamental frequency which is the frequency of the fundamental voltage command.

3. A method for controlling an electric vehicle according to claim 2, wherein the specific frequency is set to a frequency that is an integer multiple of the basic frequency, and the additional voltage command is composed of harmonics of the basic voltage command.

4. A method for controlling an electric vehicle according to claim 1, comprising estimating the rotational state of the electric motor based on the response current of the additional voltage command.

5. A method for controlling an electric vehicle according to claim 1, comprising: estimating the rotational state of the electric motor by a first estimation method based on the response current of the additional voltage command, or by a second estimation method using a magnetic flux observer; estimating the rotational state by the first estimation method when the output of the target sound is required; and stopping the addition of the additional voltage command to the basic voltage command when the output of the target sound is no longer required, and switching the method for estimating the rotational state from the first estimation method to the second estimation method.

6. A control method for an electric vehicle according to claim 1, wherein when the electric vehicle stops, the addition of the additional voltage command to the basic voltage command is stopped.

7. A method for controlling an electric vehicle according to claim 1, wherein the target sound is all or part of a vehicle approach warning sound.

8. A method for controlling an electric vehicle according to claim 7, wherein the target sound is a part of the vehicle approach notification sound, and the vehicle approach notification sound is composed of the target sound output by the electric motor and a sound played by a speaker.

9. A control device for an electric vehicle that generates a predetermined target sound from an electric motor used to drive the electric vehicle, comprising: a basic voltage command calculation unit that calculates a basic voltage command that determines the voltage to be applied to the electric motor according to the target torque that the electric motor should output; an additional voltage command setting unit that sets an additional voltage command having a specific frequency corresponding to the target sound; a final voltage command generation unit that calculates a final voltage command by adding the additional voltage command to the basic voltage command; and a PWM control unit that generates the target sound from the electric motor while causing the electric motor to output the target torque by applying a voltage to the electric motor according to the final voltage command, wherein the additional voltage command setting unit is configured to decrease the amplitude of the additional voltage command as the target torque increases, and to increase the amplitude of the additional voltage command as the target torque decreases.

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