JP2009077505A - Electric-driven vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric-driven vehicle capable of accurately detecting slippage of driving wheels without receiving an influence of a change in a wheel radius. <P>SOLUTION: The electric-driven vehicle is equipped with motors 1, 4 for driving or braking the wheels and a motor controller 33 for controlling the motors. The vehicle is further equipped with speed detectors 9, 10, 11, 12 for detecting the rotational speed of the driven wheels and the driving wheels of the vehicle, and with a slip determining device 18 computing the slip ratio of the driving wheels from the rotational speed detected value of the driven wheels and the driving wheels to determine whether the driving wheels are slipped or not. The slip determining device 18 is equipped with a means for detecting the wheel speed of the driven wheels and the driving wheels, using the wheel radius of the driven wheels and the driving wheels set in advance. The means for detecting the wheel speed adjusts the gain for computing the wheel speed detected value of the driven wheels or the wheel speed detected value of the driving wheels so that the wheel speed detected value of the driven wheels approaches the wheel speed detected value of the driving wheels in the state that the driving wheels are not slipped. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device and a control method for an electrically driven vehicle that travels when drive wheels are driven by an electric motor.

  In a vehicle running on a slippery road surface such as an icy road or a snowy road, when the driver attempts to accelerate the vehicle by depressing the accelerator, the rotational speed of the driving wheel rapidly increases, causing a phenomenon that the driving wheel idles. There is a case. On the other hand, if the driver depresses the brake to decelerate the vehicle, the rotational speed of the drive wheel may suddenly decrease and the drive wheel may lock. Hereinafter, these phenomena are collectively referred to as slip. When such a slip occurs, the behavior of the vehicle becomes unstable, the steering operation does not work, and stable running becomes difficult. Therefore, it is important to suppress the occurrence of such slip, and for that purpose, it is necessary to detect the occurrence of slip as accurately as possible.

  A method for detecting the occurrence of slip in a conventional vehicle will be described. As a method of detecting the occurrence of slip, a method of detecting each wheel speed of the driving wheel and the driven wheel, calculating a slip ratio of the driving wheel from them, and detecting when the slip ratio exceeds a specified value, There is a method of detecting the wheel speeds of the driving wheel and the driven wheel, calculating the speed difference between them, and detecting the speed difference exceeding a specified value. As an example, Patent Document 1 describes a vehicle that employs such a detection method. In addition, there are a method for detecting the wheel speed of the drive wheel, calculating its rate of change, and detecting when the rate of change exceeds a specified value, and a method for detecting when the left-right speed difference of the drive wheel exceeds the specified value. Can be mentioned. As an example, Patent Document 2 describes a vehicle that performs such a detection method.

JP 2002-27610 A US Pat. No. 6,148,269

  However, in order to detect the wheel speeds of the driving wheels and the driven wheels, the rotational speeds and radii of these wheels are required. This is because the wheel speed is proportional to the product of the rotational speed of the wheel and the radius. Here, the rotational speed of the wheel can be easily detected by using a sensor such as a rotary encoder. However, since the wheel radius changes due to changes in the external environment such as tire wear and temperature, a deviation occurs between the actual wheel speed and the detected wheel speed. For example, if the tire is worn and the wheel radius is 95% of the original size, the detected wheel speed is also 95% of the actual wheel speed, resulting in a detection error of 5%. Therefore, if the occurrence of slip is determined using the detected value of the wheel speed including such an error, there is a high possibility of causing an erroneous determination.

  In general, when slip is detected during acceleration, control is performed so as to loosen the driving force of the driving wheel, and when slip is detected during deceleration, control is performed so as to loosen the braking force of the driving wheel. Therefore, if an incorrect determination is made, the driving force or braking force is unnecessarily lowered to reduce the riding comfort and acceleration / deceleration performance even though no slip actually occurs. In spite of the occurrence, there is a possibility that the behavior of the vehicle will be further destabilized without loosening the driving force or braking force, making stable driving difficult.

  As described above, when the occurrence of slip is determined by detecting the wheel speed, the change in the radius of the wheel greatly affects the accuracy of the determination.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrically driven vehicle that can always accurately determine the occurrence of slip without being affected by changes in the radius of a wheel.

  To achieve the above object, in the present invention, in an electrically driven vehicle including an electric motor for driving or braking a wheel and an electric motor controller for controlling the electric motor, the rotational speeds of the driven wheel and the driving wheel of the vehicle are set. A speed detector for detecting, a slip determining device for calculating whether or not the driving wheel is slipping by calculating a slip ratio of the driving wheel from detected rotational speed values of the driven wheel and the driving wheel, and the slip The determiner includes means for detecting wheel speeds of the driven wheel and the driving wheel using preset wheel radii of the driven wheel and the driving wheel, and the wheel speed detecting means does not slip the driving wheel. A gay which calculates the wheel speed detection value of the driven wheel or the wheel speed detection value of the driving wheel so that the wheel speed detection value of the driven wheel and the wheel speed detection value of the driving wheel approach in the state. It is characterized in that to adjust.

  Further, in the electrically driven vehicle according to the present invention, the gain is an output of a first-order lag filter that receives a ratio of a wheel speed detection value of the driven wheel and the driven wheel as an input.

  Furthermore, in the electrically driven vehicle of the present invention, when the slip determiner determines that the drive wheel is slipping, the torque output from the electric motor is reduced.

  In order to achieve the above object, the present invention provides an electric drive vehicle including a left motor and a right motor for driving or braking a wheel, and an electric motor controller for controlling the left motor and the right motor. A speed detector for detecting rotational speeds of a left driven wheel, a left driven wheel, a right driven wheel, and a right driven wheel of a vehicle; and a slip ratio of the left driven wheel from a detected rotational speed value of the left driven wheel and the left driven wheel To determine whether or not the left driving wheel is slipping, and from the rotational speed detection values of the right driven wheel and the right driving wheel, the slip ratio of the right driving wheel is calculated to determine whether the right driving wheel is A slip determiner for determining whether or not the vehicle is slipping, and the slip determiner uses the wheel radii of the left driven wheel and the left drive wheel that are set in advance. First wheel speed detecting means for detecting a wheel speed of the left driving wheel, and wheels of the right driven wheel and the right driving wheel using a preset wheel radius of the right driven wheel and the right driving wheel. Second wheel speed detecting means for detecting the speed, wherein the first wheel speed detecting means detects the wheel speed detection value of the left driven wheel and the left driving wheel in a state where the left driving wheel is not slipping. The gain for calculating the wheel speed detection value of the left driven wheel or the wheel speed detection value of the left driving wheel is adjusted so that the wheel speed detection value approaches, and the second wheel speed detection means The wheel speed detection value of the right driven wheel or the wheel speed detection of the right driving wheel so that the wheel speed detection value of the right driven wheel and the wheel speed detection value of the right driving wheel approach each other without slipping. It is characterized in adjusting a gain for calculating a.

  Furthermore, in the electrically driven vehicle according to the present invention, the gain of the first wheel speed detecting means is an output of a first-order lag filter that receives a ratio of wheel speed detected values of the left driven wheel and the left driven wheel as input. The gain of the second wheel speed detecting means is an output of a first-order lag filter that receives a ratio of wheel speed detection values of the right driven wheel and the right driving wheel as an input.

  Furthermore, in the electrically driven vehicle of the present invention, when the slip determiner determines that the left drive wheel or the right drive wheel is slipping, the torque output from the left motor and / or the right motor is reduced. It is characterized by doing.

  According to the electrically driven vehicle of the present invention, it is possible to accurately detect the slip of the drive wheel without being affected by the change in the wheel radius. Therefore, even if the wheel radius changes due to changes in the external environment such as tire wear and temperature, it is possible to suppress slipping and to provide an electrically driven vehicle that realizes stable running of the vehicle.

  An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of an embodiment of the present invention.

  In FIG. 1, the electric motor 1 drives the wheel 3 via the gear 2, and the electric motor 4 drives the wheel 6 via the gear 5, so that the vehicle moves forward or backward. The electric motor 1 and the electric motor 4 are controlled by an electric motor controller 33, and the power converter 13 drives the electric motor 1 and the electric motor 4. The current detector 14 is connected between the power converter 13 and the electric motor 1 and detects a current flowing between them. The current detector 15 is connected between the power converter 13 and the electric motor 4 and detects a current flowing between them. The speed detector 9 is connected to the electric motor 1 and detects the rotational speed of the electric motor 1. The speed detector 10 is connected to the electric motor 4 and detects the rotational speed of the electric motor 4. The speed detector 11 is connected to the shaft of the wheel 7 and detects the rotational speed of the wheel 7. The speed detector 12 is connected to the shaft of the wheel 8 and detects the rotational speed of the wheel 8.

  The accelerator opening detector 19 detects the opening degree of the accelerator pedal according to the driver's accelerator operation, and the brake opening degree detector 20 detects the opening degree of the brake pedal according to the driver's brake operation. The detector 21 detects the steering angle according to the driver's steering operation.

  The torque command calculator 17 receives the accelerator opening detection value output from the accelerator opening detector 19, the brake opening detection value output from the brake opening detector 20, and the steering angle detection value output from the steering angle detector 21. The torque command to the motor 1 and the torque command to the motor 4 are output.

  The torque controller 16 determines the torque output from the motor 1 based on the torque command output from the torque command calculator 17, the current detection value output from the current detector 14, and the rotational speed detection value output from the speed detector 9. A gate pulse signal to the power converter 13 is output by PWM control so as to follow the torque command to the electric motor 1. The torque controller 16 outputs the motor 4 from the torque command to the motor 4 output from the torque command calculator 17, the current detection value output from the current detector 15, and the rotational speed detection value output from the speed detector 10. A gate pulse signal to the power converter 13 is output by PWM control so that the torque follows the torque command to the electric motor 4. The power converter 13 receives these gate pulse signals, and a switching element such as an IGBT performs switching at high speed, thereby realizing torque control with high response.

  The slip determination unit 18 receives the rotational speed detection values output from the speed detector 9, the speed detector 10, the speed detector 11, and the speed detector 12, and slips occur on the wheel 3 or the wheel 6 that is a driving wheel. Determine whether or not. If it is determined that slip has occurred, a torque reduction command is output to the torque command calculator 17 so that the torque output by the motor 1 and / or the motor 4 is reduced.

  Next, the configuration of the slip determiner 18 will be described.

  FIG. 2 shows a configuration diagram of the slip determiner 18. The slip determination unit 18 calculates the slip ratios of the wheels 3 and 6 which are drive wheels provided on the left and right sides of the vehicle, respectively, and determines whether or not slip has occurred.

  The gain 22 receives the rotational speed detection value of the electric motor 1 output from the speed detector 9 and outputs the rotational speed detection value of the wheel 3 by multiplying the gain given by the reciprocal of the gear ratio Gr of the gear 2. The gain 23 outputs the wheel speed detection value of the wheel 3 by taking the rotation speed detection value of the wheel 3 output from the gain 22 as input and multiplying by a preset radius Rr of the wheel 3. The gain 24 receives the rotation speed detection value of the wheel 7 output from the speed detector 11 and multiplies a preset radius Rf of the wheel 7 to output the wheel speed detection value of the wheel 7.

  The divider 25 divides the wheel speed detection value of the wheel 7 output by the gain 24 by the wheel speed detection value of the wheel 3 output by the gain 23 to output the wheel speed ratio of the wheel 7 and the wheel 3.

  The first-order lag filter 26 receives the wheel speed ratio between the wheel 7 and the wheel 3 output from the divider 25, removes the fluctuation component, and outputs a DC component. A filter other than the first-order lag filter may be used.

  The multiplier 27 multiplies the DC component of the wheel speed ratio of the wheel 7 and the wheel 3 output from the first-order lag filter 26 by the wheel speed detection value of the wheel 3 output from the gain 23, thereby correcting the detected wheel speed of the wheel 3. Is output.

  The slip ratio calculator 28 calculates the slip ratio of the wheel 3 using the corrected wheel speed detection value of the wheel 3 output from the multiplier 27 and the wheel speed detection value of the wheel 7 output from the gain 24 as inputs. Here, since the wheel 7 is a driven wheel, the wheel speed detection value of the wheel 7 is considered to represent the actual vehicle speed on the side where the wheel 7 is provided. For example, in the case of FIG. 1, the wheel speed detection value of the wheel 7 is considered to represent the actual speed on the left side of the vehicle.

  Similarly, the slip ratio of the wheel 6 is calculated using the rotation speed detection value of the electric motor 4 output from the speed detector 10 and the rotation speed detection value of the wheel 8 output from the speed detector 12 as inputs. Here, since the wheel 8 is a driven wheel, the wheel speed detection value of the wheel 8 is considered to represent the actual vehicle speed on the side where the wheel 8 is provided. For example, in the case of FIG. 1, the wheel speed detection value of the wheel 8 is considered to represent the actual speed on the right side of the vehicle.

  The determination unit 29 receives the slip ratios of the wheels 3 and 6 output from the slip ratio calculator 28 and determines that slip has occurred if any of them exceeds the specified range, and issues a torque reduction command. Output.

  With the above configuration, it becomes possible to calculate the slip ratios of the wheels 3 and 6 which are drive wheels provided on the left and right sides of the vehicle, respectively. Or slip can be suppressed by reducing the torque which the electric motor 4 outputs.

  Next, the configuration of the slip ratio calculator 28 will be described.

  FIG. 3 shows a configuration diagram of the slip ratio calculator. The subtracter 30 receives the wheel speed detection value of the driving wheel and the wheel speed detection value of the driven wheel, and outputs the difference between them. The maximum value selector 31 receives the wheel speed detection value of the driving wheel and the wheel speed detection value of the driven wheel, and outputs the larger value. The divider 32 divides the output of the subtractor 30 by the output of the maximum value selector 31 to output a slip ratio.

  Next, the relationship between the slip ratio and the friction coefficient between the wheel and the road surface will be described.

FIG. 4 shows the relationship between the slip ratio and the friction coefficient between the wheel and the road surface. Here, the region where the coefficient of friction is negative represents that the force generated between the wheel and the road surface is opposite to the traveling direction of the vehicle. In general, in the region where the slip ratio is small, the friction coefficient between the wheel and the road surface increases as the slip ratio increases, so the force acting between the wheel and the road surface also increases, and slip does not occur. . In FIG. 4, the slip does not occur in the region where the slip ratio λ satisfies λ ₁ <λ <λ ₂ .

On the other hand, when the slip ratio exceeds a certain region, the friction coefficient between the wheel and the road surface decreases as the slip ratio increases, so the force acting between the wheel and the road surface also decreases. Slip occurs. In FIG. 4, slip occurs in a region where the slip ratio λ satisfies λ> λ ₂ or λ <λ ₁ .

  Therefore, it is possible to determine whether or not a slip has occurred by calculating the slip ratio.

  Next, the operation of the slip determiner 18 will be described.

  FIG. 5 shows the operation when the wheel radii Rf and Rr set in advance in FIG. 2 coincide with the actual wheel radii.

  When slip does not occur, the actual wheel speeds of the driving wheel and the driven wheel are substantially equal. Further, since the wheel radius is equal to the set value, the wheel speed detection value is correctly detected. Therefore, as shown in FIG. 2, the wheel speed ratio 251 calculated by dividing the wheel speed detection value 241 of the driven wheel by the wheel speed detection value 231 of the driving wheel is constantly about 1, and the wheel speed ratio 251 is input. The output 261 of the first-order lag filter is constantly about 1. Therefore, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel is substantially equal to the wheel speed detection value 231 of the driving wheel, and is used for calculating the slip ratio. The wheel speed detection value 241 of the driven wheel used and the corrected wheel speed detection value 271 of the driving wheel are substantially equal. At this time, the calculated slip ratio 281 becomes substantially zero from the configuration of the slip ratio calculation shown in FIG. Accordingly, as shown in FIG. 5D, when the slip does not occur, the calculated slip ratio 281 is almost zero.

Here, for example, consider a case where the friction coefficient between the wheel and the road surface decreases due to slipping during acceleration by acceleration operation and the rotational speed 221 of the driving wheel increases as shown in FIG. When the rotational speed 221 of the driving wheel increases, the wheel speed detection value 231 of the driving wheel increases as shown in FIG. 5 (b), so that the wheel speed detection value 241 of the driven wheel becomes equal to that of the driving wheel as shown in FIG. The wheel speed ratio 251 calculated by dividing by the wheel speed detection value 231 is smaller than 1. For example, considering the case where the wheel speed detection value 231 of the drive wheel has increased twice, the wheel speed ratio 251 changes from approximately 1 to approximately 0.5. However, the output 261 of the first-order lag filter using the wheel speed ratio 251 as an input does not change abruptly if the time constant of the first-order lag filter is set to be sufficiently large, and remains substantially 1. Accordingly, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel increases almost twice as shown in FIG. 5C. At this time, the calculated slip ratio 281 increases from the configuration of the slip ratio calculation shown in FIG. 3, so that the drive wheel slips when the slip ratio 281 becomes larger than λ ₂ as shown in FIG. 5 (d). Can be detected. Note that when the friction coefficient between the wheel and the road surface is restored and the rotational speed 221 of the drive wheel is restored, the slip ratio 281 is also restored and it can be detected that the slip of the drive wheel has been eliminated.

Next, consider a case where the friction coefficient between the wheel and the road surface is lowered by, for example, becoming muddy during deceleration by a brake operation, and the rotational speed 221 of the driving wheel is reduced as shown in FIG. When the rotational speed 221 of the drive wheel decreases, the wheel speed detection value 231 of the drive wheel decreases as shown in FIG. 5 (b), so that the wheel speed detection value 241 of the driven wheel is set as shown in FIG. The wheel speed ratio 251 calculated by dividing by the wheel speed detection value 231 is larger than 1. For example, considering the case where the wheel speed detection value 231 of the drive wheel is reduced by a factor of 0.5, the wheel speed ratio 251 changes from approximately 1 to approximately 2. However, the output 261 of the first-order lag filter using the wheel speed ratio 251 as an input does not change abruptly if the time constant of the first-order lag filter is set to be sufficiently large, and remains substantially 1. Therefore, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel is reduced to about 0.5 times as shown in FIG. . At this time, the calculated slip ratio 281 decreases from the configuration of the slip ratio calculation shown in FIG. 3, so that the drive wheel slips when the slip ratio 281 becomes smaller than λ ₁ as shown in FIG. Can be detected. Note that when the friction coefficient between the wheel and the road surface is restored and the rotational speed 221 of the drive wheel is restored, the slip ratio 281 is also restored and it can be detected that the slip of the drive wheel has been eliminated.

  FIG. 6 shows an operation when the wheel radius Rf or Rr set in FIG. 2 or both Rf and Rr are different from the actual wheel radius.

  When slip does not occur, the actual wheel speeds of the driving wheel and the driven wheel are substantially equal. However, since the wheel radius is not equal to the set value, the wheel speed detection value is not correctly detected. Accordingly, the wheel speed ratio 251 calculated by dividing the detected wheel speed value 241 of the driven wheel by the detected wheel speed value 231 of the driving wheel as shown in FIG. 2 can be various values depending on the deviation of the wheel radius. For example, if the tire of the driving wheel is worn and the wheel radius is about 95% of the driven wheel, the actual rotational speed 221 of the driving wheel is 1 / 0.95≈1.05. This is about 1.05 times the actual rotation speed 111. Assuming that the preset wheel radii Rf and Rr have the same value, the wheel speed detection value 231 of the driving wheel is detected as about 1.05 times the wheel speed detection value 241 of the driven wheel. Therefore, as shown in FIG. 2, the wheel speed ratio 251 calculated by dividing the wheel speed detection value 241 of the driven wheel by the wheel speed detection value 231 of the driving wheel is approximately 1.05≈0.95, and is approximately 0.9. 95, and the output 261 of the first-order lag filter having the wheel speed ratio 251 as an input is also regularly 0.95. Therefore, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel is approximately 0.95 times the wheel speed detection value 231 of the driving wheel. However, since the wheel speed detection value 231 of the driving wheel is detected as about 1.05 times the wheel speed detection value 241 of the driven wheel, 0.95 × 1.05≈1 is used for calculating the slip ratio. The wheel speed detection value 241 of the driven wheel and the corrected wheel speed detection value 271 of the driving wheel are substantially equal. At this time, the calculated slip ratio 281 becomes substantially zero from the configuration of the slip ratio calculation shown in FIG. Therefore, as shown in FIG. 6D, when the slip does not occur, the calculated slip ratio 281 is almost zero.

Here, for example, consider a case where the friction coefficient between the wheel and the road surface decreases due to slipperiness or the like during acceleration by an accelerator operation, and the rotational speed 221 of the drive wheel increases as shown in FIG. When the rotational speed 221 of the drive wheel increases, the wheel speed detection value 231 of the drive wheel increases as shown in FIG. 6B. Therefore, the wheel speed detection value 241 of the driven wheel is set as shown in FIG. The wheel speed ratio 251 calculated by dividing by the wheel speed detection value 231 is smaller than 0.95. For example, considering the case where the wheel speed detection value 231 of the driving wheel is doubled, the wheel speed ratio 251 changes from approximately 0.95 to approximately 0.475. However, if the time constant of the first-order lag filter is set sufficiently large, the output 261 of the first-order lag filter using the wheel speed ratio 251 as an input does not change abruptly and maintains approximately 0.95. Therefore, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel is almost doubled as shown in FIG. 6C. At this time, since the calculated slip ratio 281 increases from the configuration of the slip ratio calculation shown in FIG. 3, when the slip ratio 281 becomes larger than λ ₂ as shown in FIG. Can be detected. When the friction coefficient between the wheels and the road surface returns to the original value and the rotational speed 221 of the drive wheel also returns to the original value, the slip ratio 281 also returns to the original value, and it can be detected that the slip of the drive wheel has been eliminated.

Next, consider a case where the friction coefficient between the wheels and the road surface is reduced by, for example, slipping during deceleration by braking operation, and the rotational speed 221 of the driving wheel is reduced as shown in FIG. When the rotational speed 221 of the driving wheel decreases, the wheel speed detection value 231 of the driving wheel decreases as shown in FIG. 6B. Therefore, the wheel speed detection value 241 of the driven wheel is set as shown in FIG. The wheel speed ratio 251 calculated by dividing by the wheel speed detection value 231 becomes larger than 0.95. For example, considering the case where the wheel speed detection value 231 of the drive wheel is reduced by a factor of 0.5, the wheel speed ratio 251 changes from approximately 0.95 to approximately 1.9. However, if the time constant of the first-order lag filter is set sufficiently large, the output 261 of the first-order lag filter using the wheel speed ratio 251 as an input does not change abruptly and maintains approximately 0.95. Therefore, the corrected wheel speed detection value 271 of the driving wheel obtained by multiplying the output 261 of the first-order lag filter and the wheel speed detection value 231 of the driving wheel is reduced to about 0.5 times as shown in FIG. . At this time, the calculated slip ratio 281 decreases from the configuration of the slip ratio calculation shown in FIG. 3, so that the drive wheel slips when the slip ratio 281 becomes smaller than λ ₁ as shown in FIG. 6 (d). Can be detected. When the friction coefficient between the wheels and the road surface returns to the original value and the rotational speed 221 of the drive wheel also returns to the original value, the slip ratio 281 also returns to the original value, and it can be detected that the slip of the drive wheel has been eliminated.

  By adopting the configuration of the slip determination device shown in the above embodiment, no slip occurs even if the wheel radius of the driving wheel and the driven wheel set in advance and the actual wheel radius do not coincide with each other. In this case, the slip ratio is almost zero, and when the slip occurs, the slip ratio is large or small. Therefore, it is possible to determine whether or not a slip has occurred by calculating the slip ratio.

  In addition, although the case where the preset wheel radii Rf and Rr are the same value was described for the sake of simplicity, the actual wheel radii of the driving wheel and the driven wheel are originally different, and the preset wheel radii Rf and Rr are different values. The same applies to the case of.

  In FIG. 2, the wheel speed of the drive wheel is corrected and used for the slip ratio calculation. However, the wheel speed of the driven wheel may be corrected as shown in FIG. 7.

  As described above, the slip of the driving wheel can be detected with high accuracy without being affected by the change in the wheel radius. When the slip of the driving wheel is detected, the slip determiner 18 outputs a torque reduction command, whereby the torque output from the electric motor 1 and / or the electric motor 4 is reduced, and the slip of the driving wheel is suppressed. Therefore, stable driving of the vehicle can be realized by accurately detecting the slip of the driving wheel.

  According to the present invention, the slip of the drive wheel can be detected with high accuracy without being affected by the change in the wheel radius. Therefore, even if the wheel radius changes due to changes in the external environment such as tire wear and temperature, it is possible to suppress slip, and for various types of vehicles in which the drive wheels are driven by an electric motor, Technology can be applied.

The block diagram of the control apparatus of the electric drive vehicle to which this invention is applied. The block diagram of a slip determination device. The block diagram of a slip ratio calculator. The relationship figure of the friction coefficient between a slip ratio and a wheel-road surface. The operation | movement figure of a slip determination device in case it corresponds with an actual wheel radius. The operation | movement figure of a slip determination device when different from an actual wheel radius. Another block diagram of a slip determination device.

Explanation of symbols

1 Electric motor
2,5 gear
3 wheels
4 Electric motor
6, 7, 8 Wheel 9, 10, 11, 12 Speed detector 13 Power converter
14, 15 Current detector 16 Torque controller
17 Torque command calculator
18 Slip detector 19 Accelerator position detector
20 Brake opening detector
21 Steering angle detector 22, 23, 24 Gain
25, 32 Divider 26 First-order lag filter 27 Multiplier
28 Slip ratio calculator
29 Determinator 30 Subtractor
31 Maximum value selector
33 Motor controller 111 Rotating speed of driven wheel
221 Drive wheel rotation speed
231 Wheel speed detection value of driving wheel
241 Wheel speed detection value of driven wheel 251 Wheel speed ratio
261 Output of first order lag filter 271 Corrected wheel speed detected value 281 of driving wheel Slip rate

Claims (6)

In an electric drive vehicle comprising an electric motor for driving or braking a wheel and an electric motor controller for controlling the electric motor,
A speed detector for detecting the rotational speed of the driven wheel and the drive wheel of the vehicle;
A slip determination device that determines whether or not the driving wheel is slipping by calculating a slip ratio of the driving wheel from a rotational speed detection value of the driven wheel and the driving wheel;
The slip determination device includes means for detecting wheel speeds of the driven wheel and the driving wheel using a preset wheel radius of the driven wheel and the driving wheel,
The wheel speed detection means detects the wheel speed detection value of the driven wheel or the drive wheel so that the wheel speed detection value of the driven wheel approaches the wheel speed detection value of the drive wheel in a state where the drive wheel is not slipping. An electric drive vehicle characterized by adjusting a gain for calculating a detected wheel speed of the vehicle. In claim 1,
The electric drive vehicle according to claim 1, wherein the gain is an output of a first-order lag filter having a ratio of a wheel speed detection value of the driven wheel and the drive wheel as an input. In claim 1,
An electric drive vehicle characterized by reducing torque output from the electric motor when the slip determiner determines that the drive wheel is slipping. In an electric drive vehicle comprising a left motor and a right motor for driving or braking a wheel, and an electric motor controller for controlling the left motor and the right motor,
A speed detector for detecting rotational speeds of the left driven wheel and the left driven wheel and the right driven wheel and the right driven wheel of the vehicle;
The slip ratio of the left driving wheel is calculated from the rotational speed detection values of the left driven wheel and the left driving wheel to determine whether the left driving wheel is slipping, and the right driven wheel and the right driving wheel. A slip determination device that calculates a slip ratio of the right drive wheel from the rotation speed detection value and determines whether or not the right drive wheel is slipping,
The slip determiner includes first wheel speed detection means for detecting wheel speeds of the left driven wheel and the left driving wheel using wheel radii of the left driven wheel and the left driving wheel set in advance, and a preset value. Second wheel speed detecting means for detecting wheel speeds of the right driven wheel and the right drive wheel using wheel radii of the right driven wheel and the right drive wheel,
The first wheel speed detecting means is arranged such that a wheel speed detected value of the left driven wheel and a wheel speed detected value of the left driven wheel approach each other in a state where the left driven wheel is not slipping. Adjust the gain to calculate the speed detection value or the wheel speed detection value of the left drive wheel,
The second wheel speed detecting means is arranged such that a wheel speed detection value of the right driven wheel and a wheel speed detection value of the right driving wheel approach each other so that the right driving wheel is not slipping. An electric drive vehicle characterized by adjusting a gain for calculating a speed detection value or a wheel speed detection value of the right drive wheel. In claim 4,
The gain of the first wheel speed detection means is an output of a first-order lag filter that receives as input a ratio of wheel speed detection values of the left driven wheel and the left drive wheel,
An electric drive vehicle characterized in that the gain of the second wheel speed detection means is an output of a first-order lag filter that receives a ratio of wheel speed detection values of the right driven wheel and the right drive wheel as an input. In claim 4,
An electric drive vehicle characterized by reducing torque output from the left electric motor and / or the right electric motor when the slip determination device determines that the left drive wheel or the right drive wheel is slipping.

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