Electric vehicle

Abstract

The electric vehicle disclosed in this specification includes: a motor configured to rotate the drive wheels of the electric vehicle; a sensor configured to detect the motor speed which is the rotational speed of the motor; and a control device configured to perform feedback control of the motor speed based on the detection value detected by the sensor. The control device is configured to, during the execution of the feedback control, perform: a process of extracting vibration components in a predetermined frequency band from the detection value detected by the sensor; a process of calculating an accumulated value obtained by accumulating the extracted vibration components over a predetermined period; and a process of determining whether the calculated accumulated value is included in a predetermined abnormal range.

Description

Technical Field

[0001] The technology disclosed in this specification relates to electric vehicles. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2020-127281 discloses an electric vehicle including a sensor that detects the rotational speed of a motor for driving and a control device that can perform feedback control of the motor rotational speed based on a detection value detected by the sensor. The electric vehicle determines that the drive wheels are slipping based on the motor rotational speed and the actual speed of the electric vehicle (hereinafter referred to as the vehicle speed). In this case, the electric vehicle is configured to suppress the slipping of the drive wheels by performing feedback control of the motor rotational speed and adjusting the rotational speed of the drive wheels in accordance with the vehicle speed. Summary of the Invention

[0003] In the electric vehicle of Japanese Unexamined Patent Application Publication No. 2020-127281, when slipping occurs in the drive wheels, feedback control of the motor rotational speed is performed. Regarding this feedback control, the inventors of the present invention have found a phenomenon in which the vehicle speed changes during the execution of this feedback control under certain conditions.

[0004] The mode disclosed in this specification provides an electric vehicle including: a motor configured to rotate the drive wheels of the electric vehicle; a sensor configured to detect the rotational speed of the motor as the motor rotational speed; and a control device configured to perform feedback control of the motor rotational speed based on a detection value detected by the sensor. The control device is configured to, during the execution of the feedback control, perform: a process of extracting vibration components in a predetermined frequency band from the detection value detected by the sensor; a process of calculating an accumulated value obtained by accumulating the extracted vibration components over a predetermined period; and a process of determining whether the calculated accumulated value is included in a predetermined abnormal range.

[0005] In the feedback control of the motor rotational speed, the rotational speed of the motor is adjusted based on the detection value of the motor rotational speed detected by the sensor. At this time, due to vibrations generated in the drive system including the motor and the drive wheels, external forces applied to the drive wheels from the road surface, etc., vibration components having a specific frequency appear in the detection value of the motor rotational speed. The presence of such vibration components becomes interference in the feedback control of the motor rotational speed, so there is a possibility of affecting the motor rotational speed (i.e., the vehicle speed). However, the vibration components that appear in the detection value of the motor rotational speed are minute, and their presence is not regarded as a problem. However, as the required quality of the vehicle improves, there is a possibility that the above vibration components cannot be ignored under specific conditions such as when the vehicle speed is relatively low or when slipping occurs in the drive wheels.

[0006] Regarding the above points, the control device extracts vibration components in a predetermined frequency band from the detection values detected by the sensor, and accumulates the extracted vibration components for a predetermined period. Thus, even if the vibration components included in the detection values detected by the sensor are minute, the presence of the vibration components can be reliably detected. Thus, in order to suppress fluctuations in the motor rotation speed (i.e., the vehicle speed), appropriate countermeasures can be taken in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals denote like elements, wherein:

[0008] Figure 1 A block diagram of an electric vehicle 10 showing an embodiment.

[0009] Figure 2 A graph showing the relationship between the slip ratio S and the vehicle acceleration G.

[0010] Figure 3 A flowchart showing the slip detection process executed by the control device 20.

[0011] Figure 4 A flowchart showing the slip suppression process executed by the control device 20.

[0012] Figure 5 A flowchart showing the vibration detection process executed by the control device 20.

[0013] Figure 6 A graph showing the relationship between the vehicle speed and the gain value.

[0014] Figure 7 A graph showing the relationship between the difference in the rotation speeds of the left and right drive wheels and the gain value.

[0015] Figure 8 A flowchart showing the slip suppression process executed by the control device 20 of the second embodiment.

[0016] Figure 9 A flowchart showing the slip suppression process executed by the control device 20 of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] In one embodiment of the present technology, the predetermined frequency band may also include the resonance frequency of the drive system including the motor and the drive wheels. Thus, the vibration components caused by the resonance frequency of the drive system can be detected more accurately.

[0018] In one embodiment of the present technology, the control device may also be configured to suppress the slip of the drive wheels by performing the feedback control when the slip of the drive wheels is detected.

[0019] When feedback control of the motor speed is executed to suppress slippage of the drive wheels, the slippage rate of the drive wheels is maintained within a relatively small range. Regarding this point, it has been found that in a part of a road surface with a small coefficient of friction (i.e., a road surface prone to slippage), the coefficient of friction for the drive wheels varies according to the slippage rate of the drive wheels, and this variation is significant within a relatively small range of the slippage rate. That is, when feedback control of the motor speed is executed to suppress slippage of the drive wheels, there is a possibility that the unstable behavior of the vehicle speed caused by the above vibration component is further amplified due to the change in the coefficient of friction. Regarding this point, in the above-described embodiment, when feedback control of the motor speed is executed to suppress slippage of the drive wheels, the vibration component that appears in the motor speed can be reliably detected, and necessary countermeasures can be taken in a timely manner.

[0020] In one embodiment of the present technology, the control device may also be configured to adjust the extracted vibration component with a predetermined gain when calculating the cumulative value. According to such a configuration, for example, in a situation where the user of an electric vehicle is not likely to feel the vibration, by setting the gain value to a value less than 1, it is possible to suppress the cumulative value from falling within an abnormal range. For example, in a situation where the user of an electric vehicle is likely to feel the vibration, by setting the gain value to a value greater than 1, it is possible to promote the cumulative value from falling within an abnormal range.

[0021] In one embodiment of the present technology, the control device may also be configured to change the gain according to the vehicle speed of the electric vehicle. According to the vehicle speed of the electric vehicle, the influence of the vibration on the user changes. According to such a configuration, by the control device changing the gain value according to the vehicle speed, it is possible to adjust the cumulative value according to the vehicle speed. As a result, it is possible to adjust whether the cumulative value falls within an abnormal range according to the vehicle speed.

[0022] In one embodiment of the present technology, the control device may also be configured to continuously or stepwise decrease the gain as the vehicle speed rises. When the vehicle speed rises, the user is less likely to perceive the vibration. On the other hand, when the vehicle speed is low, the user is more likely to perceive the vibration. According to the above configuration, continuously or stepwise decreasing the gain value as the vehicle speed rises can suppress the cumulative value from falling within an abnormal range in a situation where the user is less likely to perceive the vibration.

[0023] In one embodiment of the present technology, the control device may also be configured to set the gain to zero when the vehicle speed exceeds a predetermined threshold. According to such a configuration, it is possible to prevent the cumulative value from falling within an abnormal range in a situation where the vehicle speed exceeds the predetermined threshold speed and the user is less likely to perceive the vibration.

[0024] In one embodiment of the present technology, the drive wheel may also include a left drive wheel and a right drive wheel. In this case, the control device may also be configured to change the gain according to the difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel. When the difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel of an electric vehicle is large, it is difficult for the user to perceive vibration. On the other hand, when the difference is small, it is easy for the user to perceive vibration. According to the difference, the influence of vibration on the user changes. According to such a structure, the cumulative value can be adjusted according to the difference. As a result, it is possible to adjust whether the cumulative value is included in the abnormal range according to the difference.

[0025] In one embodiment of the present technology, the control device may also be configured to set the gain to zero when the difference exceeds a predetermined threshold. According to such a structure, it is possible to prevent the cumulative value from being included in the abnormal range when it is difficult for the user to perceive vibration.

[0026] In one embodiment of the present technology, the control device may also be configured to increase the target value of the motor speed in the feedback control when the cumulative value is included in the abnormal range. When the target value is low, the motor speed decreases. As a result, the wheel speed decreases. As a result, the influence of the vibration component becomes larger. According to the above structure, in the case of vibration, the vehicle speed is prevented from decreasing by increasing the target value of the motor speed. Thus, it is possible to suppress the influence of the vibration component from becoming larger.

[0027] In one embodiment of the present technology, the control device may also be configured to change the feedback gain in the feedback control when the cumulative value is included in the abnormal range. According to such a structure, it is possible to suppress the change in the motor speed caused by the feedback control. Thus, it is possible to suppress the occurrence of vibration.

[0028] In one embodiment of the present technology, the control device may also be configured to set the feedback gain in the feedback control to zero when the cumulative value is included in the abnormal range. According to such a structure, it is possible to prevent the change in the motor speed caused by the feedback control. Thus, it is possible to suppress the occurrence of vibration.

[0029] In one embodiment of the present technology, the control device may also be configured to abort the feedback control when the cumulative value is included in the abnormal range. According to such a structure, in the case of vibration, it is possible to prevent the change in the motor speed caused by the feedback control. Thus, it is possible to suppress the occurrence of vibration.

[0030] (Example)

[0031] Referring to the accompanying drawings, an electric vehicle according to an embodiment will be described. As Figure 1As shown, the electric vehicle 10 of the embodiment has four wheels (left drive wheel 2L, right drive wheel 2R, left driven wheel 6L, right driven wheel 6R). The electric vehicle 10 also includes a drive shaft 12, a differential gear 14, a propeller shaft 18, a motor 19, and a control device 20.

[0032] The left drive wheel 2L and the right drive wheel 2R are located in front of the electric vehicle 10 (i.e., Figure 1 above the paper surface of Figure 1 ), and the left driven wheel 6L and the right driven wheel 6R are located behind the electric vehicle 10 (i.e.,

[0033] below the paper surface of Figure 1 ). The left drive wheel 2L is fixed to the left end of the drive shaft 12 via a hub 4L, and the right drive wheel 2R is fixed to the right end of the drive shaft 12 via a hub 4R. The drive shaft 12 is connected to the motor 19 via the differential gear 14 and the propeller shaft 18. The motor 19 functions as an electric motor and a generator. When functioning as an electric motor, the motor 19 provides torque to the propeller shaft 18. This torque is transmitted to the drive wheels 2R, 2L via the differential gear 14 and the drive shaft 12. Thereby, the drive wheels 2R, 2L rotate, and the electric vehicle 10 travels.

[0034] The hubs 4R, 4L, 8R, 8L rotate together with the wheels 2R, 2L, 6R, 6L. Near each of the hubs 4R, 4L, 8R, 8L, a wheel speed sensor 9 is arranged. The wheel speed sensor 9 detects the rotational speed of each of the hubs 4R, 4L, 8R, 8L.

[0035] The control device 20 is a computer that controls various functions of the electric vehicle 10. Although not shown in the figure, the control device 20 includes an electronic circuit composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The control device 20 receives the rotational speeds of the hubs 4R, 4L, 8R, 8L (i.e., the wheels 2R, 2L, 6R, 6L) from each of the wheel speed sensors 9. The control device 20 estimates the vehicle speed of the electric vehicle 10 by calculating the average value of the rotational speeds of the driven wheels 6R, 6L.

[0036] The control device 20 calculates a command torque according to the operation of an accelerator (not shown) of the electric vehicle 10. The control device 20 inputs electric power for causing the motor 19 to output the calculated command torque into the motor 19. As a result, the motor 19 imparts the command torque to the propeller shaft 18. Thus, the control device 20 controls the torque (i.e., the motor speed) of the motor 19 according to the command torque. Hereinafter, this control method will be referred to as "torque control".

[0037] In addition, the motor 19 is provided with a motor sensor 19s that detects the speed of the motor 19. As will be described in detail later, the motor 19 transmits the speed of the motor 19 detected by the motor sensor 19s to the control device 20. Thereby, the control device 20 feeds back the speed of the motor 19 and controls the motor 19. That is, in addition to torque control, the control device 20 can also perform "feedback control" of the speed of the motor 19.

[0038] Refer to Figure 2 , and the relationship between the slip ratio S and the longitudinal acceleration due to gravity (hereinafter referred to as vehicle-generated G) occurring in the electric vehicle 10 will be described. In Figure 2 , the slip ratio is shown on the horizontal axis, and the vehicle-generated G is shown on the vertical axis. Here, the slip ratio S is a value indicating the instability of the driving behavior of the electric vehicle 10. More specifically, the slip ratio is a value indicating the degree of difference between the average value of the rotational speeds of the drive wheels 2R and 2L (refer to Figure 1 ) and the vehicle speed of the electric vehicle 10. When each of the drive wheels 2R and 2L slips (i.e., when the slip ratio S increases), the rotational speed of each of the drive wheels 2R and 2L becomes relatively larger than the vehicle speed. That is, the slip ratio S is proportional to the difference between the average value of the rotational speeds of the drive wheels 2R and 2L and the vehicle speed. In addition, the slip ratio is inversely proportional to the vehicle speed. As a result, the slip ratio S is calculated by, for example, the following formula (1).

[0039] S = (average value of rotational speeds of drive wheels 2R and 2L - vehicle speed) / vehicle speed...(1)

[0040] Therefore, when the value obtained by subtracting the vehicle speed from the average value of the rotational speeds of the drive wheels 2R and 2L is the same, the smaller the vehicle speed, the larger the slip ratio S becomes. The inventors of the present invention investigated the relationship between the slip ratio and the vehicle-generated G under various road surface conditions. As a result, as shown by the dotted line graph in Figure 2 , on an icy road surface, that is, an ice plate road surface, even if the slip ratio S changes, the value of the vehicle-generated G remains substantially constant. However, as shown by the inflection range CA of the solid line graph in Figure 2 , it was found that on a road surface such as a wet brick road surface where water is retained on the road surface, when the slip ratio decreases, the vehicle-generated G rises sharply.

[0041] Therefore, especially on a wet brick road surface, when the slip ratio changes within the turning-back range CA, a large change in G occurs in the vehicle. In other words, on a wet brick road surface, when the slip ratio changes within the turning-back range CA, vibration occurs in the electric vehicle 10.

[0042] (Slip Detection Process)

[0043] Refer to Figure 3 , and explain the slip detection process executed by the control device 20. While controlling the torque of the motor 19 with the above torque control during the running of the electric vehicle 10, the control device 20 executes Figure 3 the slip detection process shown. The slip detection process is a process for detecting the slip of each drive wheel 2R, 2L of the electric vehicle 10.

[0044] In S2, the control device 20 receives the rotational speeds of the driven wheels 6R, 6L from the wheel speed sensors 9 corresponding to the driven wheels 6R, 6L. Next, in S4, the control device 20 calculates the vehicle speed of the electric vehicle 10 based on the average value of the received rotational speeds of the driven wheels 6R, 6L. In S6, the control device 20 calculates the estimated rotational speeds of the drive wheels 2R, 2L based on the calculated vehicle speed. Here, the estimated rotational speed refers to the rotational speed of each drive wheel 2R, 2L required to travel at the calculated vehicle speed in a state where the drive wheels 2R, 2L do not slip.

[0045] Furthermore, in S8, the control device 20 receives the actual rotational speeds of the drive wheels 2R, 2L from the wheel speed sensors 9 corresponding to the drive wheels 2R, 2L, and detects the rotational speeds of the drive wheels 2R, 2L based on this rotational speed. In S10, the control device 20 compares the actual rotational speeds of the received drive wheels 2R, 2L with the estimated rotational speeds, and calculates the excess amount by which the actual rotational speeds of the drive wheels 2R, 2L exceed the estimated rotational speeds. Furthermore, the control device 20 accumulates this excess amount.

[0046] In S12, the control device 20 compares the accumulated excess amount obtained by accumulating the excess amount with the accumulated amount threshold. Here, the accumulated amount threshold is a value preset for the control device 20 and is a threshold for determining whether each drive wheel 2R, 2L slips. When the accumulated excess amount exceeds the accumulated amount threshold (Yes in S12), the control device 20 determines that each drive wheel 2R, 2L slips, interrupts the torque control, and executes the slip suppression process. On the other hand, when the accumulated excess amount does not exceed the accumulated amount threshold (No in S12), the control device 20 determines that each drive wheel 2R, 2L does not slip, continues the torque control, and executes the process of S2 again. In this way, the control device 20 detects whether each drive wheel 2R, 2L slips during the running of the electric vehicle 10.

[0047] (Slip suppression process)

[0048] Refer to Figure 4 , and explain the slip suppression process executed by the control device 20. Slip suppression control is a feedback control of the motor speed executed to suppress the slip of each drive wheel 2R, 2L when the slip of each drive wheel 2R, 2L is detected. In S20, the control device 20 receives the motor speed as the speed of the motor 19 from the motor sensor 19s. Next, in S22, the control device 20 sets a target speed that becomes the target value of the speed of the motor 19. Here, for example, the target speed is obtained by multiplying the above-mentioned estimated speed by a coefficient such as a predetermined slip rate for matching the speeds of the drive wheels 2R, 2L with the speed of the motor 19.

[0049] In S24, the control device 20 determines whether the vibration flag is ON. As referred to Figure 5 described later, the vibration flag indicates that vibration in a predetermined frequency band occurs in the motor 19. When the vibration flag is not ON (in S24, "No"), the control device 20 skips the process of S26 and proceeds to S28.

[0050] In S28, the control device 20 controls the motor 19 based on the difference between the motor speed detected in S20 and the target speed.

[0051] When the vibration flag is ON (in S24, "Yes"), the control device 20 increases the target speed set in S22. In this case, the control device 20 controls the motor 19 based on the difference between the motor speed detected in S20 and the increased target speed in S28. As shown in the fold-back range CA of Figure 2 , the vehicle acceleration G rises sharply in the interval where the slip rate S is low (0 to about 0.3). By increasing the target speed, the difference between the average rotational speed of the drive wheels 2R, 2L and the vehicle speed increases. As a result, the slip rate S becomes larger. Thus, it is possible to suppress the slip rate S from being included in the fold-back range CA and suppress the occurrence of vibration. In this way, the control device 20 of the present embodiment executes feedback control of the motor speed when the slip of each drive wheel 2R, 2L is detected.

[0052] (Vibration detection process)

[0053] Refer to Figure 5 , and explain the vibration detection process executed by the control device 20. The vibration detection process is executed by the control device 20 during the running of the electric vehicle 10. The vibration detection process is a process for detecting vibration that occurs particularly around the motor 19 when the slip of each drive wheel 2R, 2L is detected.

[0054] In S30, the control device 20 determines whether the slip suppression process is being executed at the current time point (refer to Figure 4) When the slip suppression process is not executed at the current time point (No in S30), the control device 20 sets the vibration flag to OFF in S46 and ends the vibration detection process.

[0055] When the slip suppression process is being executed at the current time point (Yes in S30), in S32, the control device 20 performs a band-pass filter process on the motor speed detected in S20 (refer to Figure 4 ). Here, the band-pass filter process is a process of transforming the frequency of the motor speed into a predetermined frequency band. In the present embodiment, the predetermined frequency band includes the resonance frequency of the drive system including the motor 19, the drive shaft 12, and the drive wheels 2R and 2L, for example, 12 Hz. By transforming the frequency of the motor speed into a frequency band including the resonance frequency of the drive system, it is possible to extract the vibration components in the motor speed that are highly likely to cause resonance of the drive system. In addition, in a modified example, the predetermined frequency band may be the resonance frequency of the entire electric vehicle 10 or the resonance frequency of the motor 19 alone.

[0056] Next, in S34, the control device 20 acquires predetermined information from various parts of the electric vehicle 10 and calculates a gain value using the acquired information. The gain value is a value for adjusting the vibration components processed in S32.

[0057] (Gain value)

[0058] Here, for the time being, refer to Figure 6 and Figure 7 to describe the gain value of the present embodiment. The control device 20 of the present embodiment calculates the gain value using the difference between the vehicle speed and the rotational speeds of the drive wheels 2R and 2L. As Figure 6 shown, when the vehicle speed calculated by the control device 20 in S4 (refer to Figure 3 ) is 15 km / h or less, the gain value is set to 1.0. When the vehicle speed exceeds 15 km / h, the control device 20 sets the gain value to zero.

[0059] According to the vehicle speed of the electric vehicle 10, the influence of vibration on the user changes. Specifically, when the vehicle speed exceeds 15 km / h, assuming vibration occurs, it is difficult for the user to perceive the occurrence of vibration. On the other hand, when the vehicle speed is 15 km / h or less, when vibration occurs, the user is likely to perceive the occurrence of vibration. The control device 20 of the present embodiment sets the gain value to zero when the vehicle speed exceeds 15 km / h. Thereby, it is possible to prevent the vibration from being detected in vain in a situation where the user is unlikely to perceive the occurrence of vibration.

[0060] In addition, the control device 20 calculates the difference in the rotational speeds of the respective drive wheels 2R and 2L received from the wheel speed sensors 9 corresponding to the respective drive wheels 2R and 2L. As Figure 7 shown, when the difference in the rotational speeds of the respective drive wheels 2R and 2L is 5 km / h or less, the control device 20 sets the gain value to 1.0. When the difference exceeds 5 km / h, the control device 20 sets the gain value to zero.

[0061] According to the difference in the rotational speeds of the respective drive wheels 2R and 2L, the influence of the vibration on the user changes. Specifically, when the difference in the rotational speeds of the respective drive wheels 2R and 2L exceeds 5 km / h, even if vibration is assumed to occur, it is difficult for the user to perceive the occurrence of the vibration. On the other hand, when the difference in the rotational speeds of the respective drive wheels 2R and 2L is 5 km / h or less, when vibration occurs, the user is likely to perceive the occurrence of the vibration. In the control device 20 of the present embodiment, when the difference in the rotational speeds of the respective drive wheels 2R and 2L exceeds 5 km / h, the gain value is set to zero. Thereby, it is possible to prevent the vibration from being detected in vain in a situation where the user is unlikely to perceive the occurrence of the vibration.

[0062] Next, returning to Figure 5 , the vibration detection process will be described. In S36, the control device 20 adjusts the vibration component by multiplying the vibration component processed in S32 by the gain value described with reference to Figure 6 , Figure 7 . Next, in S40, the cumulative value of the vibration component adjusted in S36 is calculated.

[0063] In S40, the control device 20 determines whether a predetermined period has elapsed. Here, the predetermined period is a period during which it can be determined that the vibration of the above drive system continues to occur, for example, 1000 msec. If the predetermined period has not elapsed (in S40, "No"), the control device 20 returns to S34 and calculates the gain value again. That is, the control device 20 repeats the processes of S34 to S38 until the predetermined period has elapsed.

[0064] When the predetermined period has elapsed (in S40, "Yes"), the control device 20 compares the cumulative value accumulated during the predetermined period with the vibration determination value in S42. The vibration determination value is a threshold value for determining the occurrence of the vibration of the drive system and is stored in the control device 20 in advance. When the cumulative value exceeds the vibration determination value (in S42, "Yes"), the control device 20 determines that the vibration of the drive system has occurred, proceeds to S44, turns on the above vibration flag, and ends the vibration detection process. On the other hand, when the cumulative value is equal to or less than the vibration determination value (in S42, "No"), the control device 20 determines that the vibration of the drive system has not occurred, proceeds to S46, turns off the above vibration flag, and ends the vibration detection process.

[0065] (Effect of this embodiment)

[0066] As described above, in the slip suppression process, the control device 20 detects the motor speed and adjusts the speed of the motor 19. Due to vibrations generated in the drive system such as the motor 19 and the drive wheels 2R and 2L, and external forces applied to the drive wheels 2R and 2L from the road surface, the detected motor speed includes vibration components having a specific frequency. This vibration component becomes an interference in the feedback control of the motor speed performed in the slip suppression process. For example, as described with reference to Figure 3 , it causes a change in vehicle G. In the slip suppression process of the control device 20 of the electric vehicle 10 of this embodiment, the vibration component in a predetermined frequency band is extracted from the detected motor speed (S32). Further, the control device 20 accumulates the extracted vibration components during a predetermined period (S38), compares the accumulated value with a vibration determination value, and detects the occurrence of vibration. Thus, the occurrence of vibration can be detected based on the minute vibration components included in the motor speed.

[0067] (Second Embodiment)

[0068] Refer to Figure 8 to describe the slip suppression process performed by the control device 20 of the electric vehicle 10 of the second embodiment. In the slip suppression process of the control device 20 of the second embodiment, when the vibration flag is ON (Yes in S24), instead of the process of S26, in S56, the feedback gain is set to zero. In other respects, the electric vehicle 10 of the second embodiment has the same structure as the electric vehicle 10 of the first embodiment.

[0069] Thus, in the case of vibration occurrence, the feedback control of the motor speed is substantially interrupted. As a result, the speed of the motor 19 is not changed by the feedback control. Therefore, the occurrence of vibration can be suppressed. Further, in a modified example, the control device 20 may also make the feedback gain greater than 1 in S56. By further strengthening the feedback control of the motor speed, the vibration can be suppressed.

[0070] (Third Embodiment)

[0071] Refer to Figure 9 to describe the slip suppression process performed by the control device 20 of the electric vehicle 10 of the third embodiment. In the slip suppression process of the control device 20 of the third embodiment, when the vibration flag is ON (Yes in S24), instead of the process of S26, in S66, the feedback control of the motor speed is aborted. In other respects, the electric vehicle 10 of the third embodiment has the same structure as the electric vehicle 10 of the first embodiment. As a result, the speed of the motor 19 is not changed by the feedback control. Therefore, the occurrence of vibration can be suppressed.

[0072] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the claims. The technology described in the claims includes examples obtained by various modifications and changes to the specific examples illustrated above. The following are examples of modifications to the above embodiments.

[0073] (Modification Example 1) In the vibration detection process, the control device 20 may also not multiply the filtered motor speed by the gain value. That is, in this modification example, the processes of S34 and S36 can be omitted. Figure 5 In addition, in other modification examples, a vehicle-specific gain value may be used instead of the difference in the vehicle speed and the rotational speeds of the respective drive wheels 2R and 2L. In this case, for example, when the electric vehicle 10 has a structure that is not easily affected by vibration, the vehicle-specific gain value can be set low, and when the electric vehicle 10 has a structure that is easily affected by vibration, the vehicle-specific gain value can be set high.

[0074] (Modification Example 2) In the vibration detection process, the control device 20 may also set the gain value to 0.5 when the vehicle speed exceeds 10 km / h and set the gain value to zero when the vehicle speed exceeds 15 km / h. That is, the control device 20 may also decrease the gain value step by step. In other modification examples, the control device 20 may continuously decrease the gain value as the vehicle speed increases.

[0075] The technical elements described in this specification or the drawings exhibit technical usefulness alone or through various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of these purposes itself has technical usefulness.

Claims

1. An electric vehicle, characterized in that, Comprising: A motor configured to rotate the drive wheels of the electric vehicle; A sensor configured to detect the motor speed which is the rotational speed of the motor; And A control device configured to perform feedback control of the motor speed based on the detection value detected by the sensor, wherein The control device is configured to, during the execution of the feedback control, implement: A process of extracting vibration components in a predetermined frequency band from the detection value detected by the sensor; A process of calculating an accumulated value obtained by accumulating the extracted vibration components over a predetermined period; and A process of determining whether the calculated accumulated value is included in a predetermined abnormal range, The control device is configured to adjust the extracted vibration components with a predetermined gain when calculating the accumulated value, The drive wheels include a left drive wheel and a right drive wheel, The control device is configured to change the gain according to the difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel, The control device is configured to set the gain to zero when the difference exceeds a predetermined threshold.

2. The electric vehicle according to claim 1, wherein The predetermined frequency band includes the resonance frequency of the drive system including the motor and the drive wheels.

3. The electric vehicle according to claim 1 or 2, wherein The control device is configured to suppress slippage of the drive wheels by executing the feedback control when slippage of the drive wheels is detected.

4. The electric vehicle according to claim 1, wherein The control device is configured to change the gain according to the vehicle speed of the electric vehicle.

5. The electric vehicle according to claim 4, wherein The control device is configured to continuously or stepwise decrease the gain as the vehicle speed increases.

6. The electric vehicle according to claim 4 or 5, wherein The control device is configured to set the gain to zero when the vehicle speed exceeds a predetermined threshold speed.

7. The electric vehicle according to any one of claims 1, 2, 4, 5, wherein The control device is configured to increase the target value of the motor speed in the feedback control when the accumulated value is included in the abnormal range.

8. The electric vehicle according to any one of claims 1, 2, 4, 5, wherein The control device is configured to change the feedback gain in the feedback control when the accumulated value is included in the abnormal range.

9. The electric vehicle according to any one of claims 1, 2, 4, 5, wherein The control device is configured to set the feedback gain in the feedback control to zero when the accumulated value is included in the abnormal range.

10. The electric vehicle according to any one of claims 1, 2, 4, 5, wherein The control device is configured to abort the feedback control when the accumulated value is included in the abnormal range.

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