JP2004120876A - Motor control method of electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify or omit a sensor used for controlling in a motor control method of an electric vehicle, and to accurately and quickly response to operation amount of an accelerator for stable travel even if a load fluctuates. <P>SOLUTION: A speed deviation ε between a vehicle speed v of the electric vehicle and a speed command value (c) corresponding to the step-in amount of an accelerator pedal 32 is multiplied by a gain G to provide an intermediate variable Gε. An integrator input a1 is acquired by limiting the intermediate variable Gε within the range of a first threshold value L1 with a positive sign or second threshold value L2 with a negative sign. Integration is performed at an integrator 62 to generate a torque command value T through a torque command part 64. A current I which is based on the torque command value T is made to flow to rotate a motor 14. The gain G, first threshold value L1, and second threshold value L2 are set and changed according to conbination of positive/negative sign of the speed deviation ε and that of the torque command value T. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor control method for an electric vehicle that calculates a torque command value based on a speed command value corresponding to an accelerator operation amount and a vehicle speed of the electric vehicle, and drives a driving motor in accordance with the torque command value. About.
[0002]
[Prior art]
In a conventional electric vehicle, feedback control is performed by detecting a current flowing through a field coil of a motor in order to improve responsiveness corresponding to an accelerator operation and a load change (for example, see Patent Document 1). Further, an angle sensor or a speed sensor is provided to perform control corresponding to the vehicle speed. In order to appropriately and immediately respond to the vehicle speed, high-resolution angle sensors and speed sensors are employed.
[0003]
[Patent Document 1]
JP-A-9-130913 (paragraphs [0012] and [0013] and FIG. 2)
[0004]
[Problems to be solved by the invention]
By the way, a sensor for detecting a current and a sensor for detecting a rotation angle are relatively expensive, and cause a rise in the price of an electric vehicle.
[0005]
When the sensor for detecting the current is not used, the maximum response speed is determined by the time constant of the motor itself, so that the response speed is relatively slow. In addition, if a sensor with low resolution is used as a sensor for detecting the rotation angle or the speed, inappropriate control such as a delay with respect to the vehicle speed occurs. That is, the response of the vehicle speed to the depression amount of the accelerator pedal is reduced, and the vehicle speed becomes unstable at the time of a load change such as a change in the slope of a slope.
[0006]
The present invention has been made in view of such a problem, and omits or simplifies a sensor used for controlling a traveling motor, accurately and quickly responds to an operation amount of an accelerator, even when a load change occurs. An object of the present invention is to provide a motor control method for an electric vehicle that can run stably.
[0007]
[Means for Solving the Problems]
A motor control method for an electric vehicle according to the present invention includes: a step of obtaining a first intermediate variable obtained by multiplying a gain between a deviation between a speed command value corresponding to an accelerator operation amount and a vehicle speed of the electric vehicle; Obtaining a second intermediate variable by limiting the range between a first positive threshold and a second negative threshold; generating a torque command value by integrating the second intermediate variable; Driving the driving motor in accordance with the combination of the gain, the first threshold value, and / or the second threshold value in accordance with the combination of the sign of the deviation and the sign of the torque command value, respectively. Changing step.
[0008]
As described above, if the gain, the first threshold value, and the second threshold value are changed according to the traveling state of the electric vehicle, and then the integration is performed, it is not necessary to detect the traveling speed of the vehicle with high accuracy. Further, it is possible to accurately and quickly respond to the operation amount of the accelerator without detecting the current flowing through the motor, and to stably run even when the load changes.
[0009]
In this case, when the torque command value is positive, the deviation is positive, and the vehicle speed is equal to or less than a predetermined speed, the gain is increased in proportion to the vehicle speed, and the first threshold is set to the vehicle speed. If it is reduced in proportion, the response of the torque command value to the deviation and the rotation of the motor can be made smooth.
[0010]
Further, when the torque command value is positive and the deviation is negative, when the gain is increased from the reference gain value and the second threshold value is decreased from the reference threshold value, the accelerator operation amount is reduced. Responsiveness of the vehicle speed and unnecessary acceleration at the end of climbing a hill can be prevented.
[0011]
Further, when the torque command value is negative, the deviation is negative, and the vehicle speed is equal to or less than a predetermined speed, the gain is increased in proportion to the vehicle speed, and the second threshold value is proportional to the vehicle speed. When it is decreased, the response of the torque command value to the deviation becomes smooth, and the electric vehicle can be slowly decelerated or stopped.
[0012]
Furthermore, when the torque command value is negative and the deviation is positive, when the gain is increased from a reference gain value and the first threshold value is increased from the reference threshold value, an accelerator operation amount is increased. Responsiveness of the vehicle, and unnecessary deceleration at the end of a downhill can be prevented.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of a motor control method for an electric vehicle according to the present invention will be described with reference to the accompanying FIGS.
[0014]
The motor control method for an electric vehicle according to the present embodiment is mainly executed by an ECU (Electric Control Unit) 12 in electric vehicle 10 shown in FIG.
[0015]
As shown in FIG. 1, the electric vehicle 10 travels using a motor 14 as a power source, and a rotating shaft of the motor 14 is connected to a differential gear 16 having a shifting function. The rotational power of the motor 14 is transmitted to the front wheels 20 via the differential gear 16 and the axle 18.
[0016]
The ECU 12 performs processing under the control of the CPU 30 that operates according to the program 28. The ECU 12 is supplied with a signal of a volume 34 for detecting the amount of depression of the accelerator pedal 32. The ECU 12 calculates a signal value for the motor 14 based on the signal of the volume 34 and supplies it to an output interface (output I / F) 36. The output interface 36 supplies a control signal to the inverter 38, which controls the electric power supplied from the battery 40 and drives the motor 14 based on the command signal.
[0017]
The motor 14 is provided with a Hall IC type rotation angle detection sensor 42 for detecting the position of the magnetic pole. Since the rotation angle detection sensor 42 is of the Hall IC type, it has an angle detection resolution corresponding to the number of poles of the motor 14, and the angle detection resolution is low. Hall IC type sensors are less expensive than high resolution sensors such as encoders.
[0018]
The signal of the rotation angle detection sensor 42 is supplied to the ECU 12 via an input interface (input I / F) 44.
[0019]
As shown in FIG. 2, the ECU 12 performs control based on a signal of a volume 34 indicating a depression amount (operation amount) of an accelerator pedal 32 and a signal of a rotation angle detection sensor 42.
[0020]
In the ECU 12, the speed command converter c calculates a speed command value c from the signal of the volume. That is, as shown in FIG. 3, the signal of the volume 34 substantially corresponds to the speed command value c, and when the signal of the volume 34 changes, the speed command value c changes so as to have a predetermined inclination. The speed command value c may reflect information relating to the amount of depression of a brake pedal (not shown).
[0021]
Returning to FIG. 2, the ECU 12 subtracts the speed command value c and the vehicle speed v at a subtraction point 54. The speed deviation ε, which is the result of the subtraction, is supplied to the gain multiplication unit 56, and is multiplied by the gain G to obtain an intermediate variable (first intermediate variable) Gε. In the ECU 12, the depression amount of the accelerator pedal 32 becomes the speed command value c via the speed command conversion unit 52, and the ECU 12 performs control while feeding back the vehicle speed v. Therefore, the vehicle speed control is basically performed. By performing the vehicle speed control, the speed can be delicately controlled even when the load fluctuates or under heavy load, and unexpected behavior such as sudden acceleration when the accelerator pedal 32 is depressed does not occur.
[0022]
The intermediate variable Gε is supplied to the limiter 58 and is limited to a range between a first threshold L1 having a positive sign and a second threshold L2 having a negative sign. The gain G, the first threshold L1, and the second threshold L2 are set by the limiter / gain setting unit 60, respectively.
[0023]
The value limited by the limiter 58 is supplied to the integrator 62 as an integrator input (second intermediate variable) a1 and integrated. “S” shown in the block of the integrator 62 in FIG. 2 is a differential operator.
[0024]
The subtraction point 54, the gain multiplication unit 56, the limiter 58 and the integrator 62 constitute a speed control unit 63.
[0025]
The value integrated by the integrator 62 is supplied to the torque command unit 64 as an integrator output a2. The torque command section 64 amplifies the supplied integrated value output a2 to generate a torque command value T. The torque command value T is supplied to a limiter / gain setting unit 60 and a duty control unit 66. The duty control unit 66 sets the torque command value T to a pulse T1. This pulse T1 is supplied to an inverter 38 via an output interface 36, and the inverter 38 causes a current I to flow through the motor 14 based on the pulse T1. When the current I flows, a rotation torque is generated in the motor 14 and the motor 14 rotates. Note that a sensor for detecting the current I flowing through the motor 14 and a feedback unit are not provided. Therefore, when the pulse T1 changes in a small width, the current I changes relatively slowly according to the time constant such as the internal resistance.
[0026]
The rotation angle of the vehicle speed v detected by the rotation angle detection sensor 42 is supplied to the angle signal calculator 68 and the speed signal calculator 70 via the input interface 44. The angle signal calculation section 68 calculates information on the supplied angle to generate an angle signal θ, and supplies the generated angle signal θ to the duty control section 66. The speed signal calculation unit 70 calculates the information on the supplied angle to generate the vehicle speed v, and supplies it to the duty control unit 66 and the limiter / gain setting unit 60.
[0027]
The duty control unit 66 converts the torque command value T into a pulse T1, and controls and outputs the duty and phase of the pulse T1 based on the supplied angle signal θ and vehicle speed v.
[0028]
The limiter / gain setting section 60 sets the gain G, the first threshold L1, and the second threshold L2 based on the torque command value T, the vehicle speed v, and the speed command value c.
[0029]
The operation of the limiter / gain setting section 60 will be described with reference to FIG.
[0030]
The limiter / gain setting unit 60 obtains the speed deviation ε in the same manner as the operation of the subtraction point 54, and then checks the sign of the speed deviation ε as shown in step S1 of FIG. The process proceeds to S2, and if negative, proceeds to step S5.
[0031]
In step S2, the sign of the torque command value T is checked. If it is positive, the process proceeds to step S3, and if it is negative, the process proceeds to step S4.
[0032]
In step S5, the sign of the torque command value T is checked. If it is positive, the process proceeds to step S6, and if it is negative, the process proceeds to step S7.
[0033]
In step S3, a first gain pattern of the gain G (see FIG. 7A) and a first limiter pattern of the first threshold L1 (see FIG. 7B) are applied. Step S3 is a state in which the vehicle travels while performing power running, for example, a state in which the electric vehicle 10 starts and climbs a hill. In these states, it is necessary that the response of the rotation of the motor to the accelerator pedal 32 be good. Here, power running refers to an operating state in which the motor 14 generates a positive torque. The state where step S3 is executed, that is, the state where both the speed deviation ε and the torque command value T are positive is referred to as a first traveling pattern.
[0034]
In step S4, a fourth gain pattern of the gain G (see FIG. 11A) and a fourth limiter pattern of the first threshold L1 (see FIG. 11B) are applied. This step S4 is, for example, a state in which the vehicle has gone down a hill and has entered a flat portion. In other words, the torque command value T is in the negative range, and while regeneration is performed, the speed deviation ε is positive, and it is necessary to prevent excessive deceleration. The state where step S4 is executed, that is, the state where the speed deviation ε is positive and the torque command value T is negative is called a fourth traveling pattern.
[0035]
In step S6, the second gain pattern of the gain G (see FIG. 8A) and the second limiter pattern of the second threshold L2 (see FIG. 8B) are applied. This step S6 is, for example, a state in which the vehicle has entered the flat portion at the end of the uphill. That is, it is necessary to prevent over-acceleration in a state where the torque command value T is in the positive range and the power running is performed, while the speed deviation ε is negative. The state where step S6 is executed, that is, the state where the speed deviation ε is negative and the torque command value T is positive is called a second traveling pattern.
[0036]
In step S7, a third gain pattern of the gain G (see FIG. 10A) and a third limiter pattern of the second threshold L2 (see FIG. 10B) are applied. This step S7 is, for example, a state where the vehicle is decelerating or traveling downhill. In these states, smooth deceleration and a smooth feeling of deceleration are required. The state where step S7 is executed, that is, the state where both the speed deviation ε and the torque command value T are negative is referred to as a third traveling pattern.
[0037]
As described above, the gain G set in the first to fourth gain patterns is supplied to the gain multiplication unit 56 (see FIG. 2), and is multiplied by the speed deviation ε. Further, the first and second threshold values L1 and L2 set by the first to fourth limit patterns are supplied to the limiter 58 to limit the intermediate variable Gε.
[0038]
As shown in FIG. 5, the division of the first to fourth gain patterns and the first to fourth limiter patterns applied to the first to fourth traveling patterns is performed in the first quadrant to the fourth quadrant on the two-dimensional coordinates. It corresponds to a quadrant. The first to fourth gain patterns and the first to fourth limiter patterns may be recorded in a table format on a memory (not shown), and the vehicle speed v may be referred to as a parameter.
[0039]
By the way, the torque command value T is generated in the torque command section 64. However, the subsequent duty control section 66, the output interface 36, and the inverter 38 have a sufficiently high processing speed and almost zero delay, so that the torque When the command value T is positive, the motor 14 performs power running, and when the torque command value T is negative, regeneration is performed. Therefore, the first to fourth gain patterns and the first to fourth limiter patterns that are set based on the torque command value T have a gain G, a first threshold L1, and a second threshold L2 depending on the powering state and the regenerative state of the motor 14. Will be set.
[0040]
The first to fourth gain patterns, the first to fourth limiter patterns, and the effects of applying these patterns will be described later.
[0041]
Each function in the ECU 12 shown in FIG. 2 is actually a process recorded in the program 28, and is executed by the CPU 30.
[0042]
Next, a method of controlling the motor 14 using the accelerator pedal 32, the ECU 12, the inverter 38, and the like configured as described above will be described with reference to FIG. The flowchart of FIG. 6 is mainly executed by the CPU 30 based on the contents of the program 28, and is repeatedly executed at a predetermined minute time period.
[0043]
First, in step S101 in FIG. 6, the gain G, the first threshold L1, and the second threshold L2 are generated by the operation of the limiter / gain setting unit 60 (see FIG. 4), and supplied to the gain multiplication unit 56 and the limiter 58.
[0044]
Next, in step S102, the vehicle speed v is subtracted from the speed command value c at the subtraction point 54 to obtain a speed deviation ε.
[0045]
Next, in step S103, the intermediate variable Gε is obtained by multiplying the speed deviation ε and the gain G by the operation of the gain multiplication unit 56.
[0046]
Further, in step S104, the intermediate variable Gε is limited to the range between the first threshold L1 and the second threshold L2 by the operation of the limiter 58, and the integrator input a1 is obtained. That is, when the first limiter pattern or the second limiter pattern is applied, the limitation is performed when the intermediate variable Gε is larger than the first threshold L1. Further, when the third limiter pattern or the fourth limiter pattern is applied, the limitation is performed when the intermediate variable Gε is smaller than the second threshold L2.
[0047]
Next, in step S105, the integrator input a1 is integrated by the integrator 62 to obtain an integrator output a2. By performing the integration, the steady value of the speed deviation ε, that is, the steady speed deviation can be extremely reduced.
[0048]
Next, in Step S106, the torque command value T is generated by multiplying the integrator output a2 by a constant by the operation of the torque command unit 64. The torque command value T is supplied to the duty control unit 66 and the limiter / gain setting unit 60. The limiter / gain setting unit 60 uses the torque command value T to generate the gain G, the first threshold L1, and the second threshold L2.
[0049]
Further, in step S107, the duty control unit 66 performs duty control and phase control to generate a pulse T1. The pulse T1 is supplied to the inverter 38 via the output interface 36.
[0050]
Furthermore, in step S108, the current I flows through the motor 14 by the action of the inverter 38. As described above, since there is no means for detecting the current I, the actually flowing current I responds according to the time constant due to the winding resistance of the motor 14 and the like.
[0051]
Next, the first to fourth gain patterns, the first to fourth limiter patterns, and the effects of applying these patterns will be described with reference to FIGS. 7A to 12.
[0052]
As shown in FIG. 7A, in the first gain pattern, the gain G is proportionally increased from the speed 0 to the speed v1. ₀ Set to. Reference gain value G ₀ Is set to a value at which the rotation of the motor 14 and the running state of the electric vehicle 10 are not vibratory, and a relatively large value.
[0053]
As shown in FIG. 7B, in the first limiter pattern, the first threshold value L1 is changed from the speed 0 to the speed v2 to the reference threshold value L. ₀₁ Is proportionally reduced based on In the range above the speed v2, the first threshold L1 is set to a relatively small constant value.
[0054]
In the first traveling pattern, a first gain pattern and a first limiter pattern are applied. Thus, when the electric vehicle 10 starts or accelerates at a low speed, the gain G is set to a relatively small value, so that the response of the torque command value T to the speed deviation ε is smooth. Moreover, at the time of start or low-speed running acceleration, the first threshold L1 is a relatively large value, for example, the reference threshold L. ₀₁ Therefore, when the value of the speed deviation ε is large, a relatively large value is supplied to the integrator 62, and the electric vehicle 10 can be rapidly accelerated to shift to high-speed traveling.
[0055]
When the electric vehicle 10 is running at a high speed, the gain G is a relatively large reference gain value G. ₀ Therefore, the response of the torque command value T to the speed deviation ε is fast. In addition, since the first threshold value L1 is set to a relatively small value during high-speed running, an excessive value is not continuously supplied to the integrator 62, and as a result, the electric vehicle 10 can be stably driven. it can.
[0056]
Since the first gain pattern and the first limiter pattern only need to record general characteristics with respect to the vehicle speed v, it is easy to create these patterns. Similarly, it is easy to create the second to fourth gain patterns and the second to fourth limiter patterns.
[0057]
As shown in FIG. 8A, in the second gain pattern, the gain G is set to the reference gain value G. ₀ Set to a larger constant value.
[0058]
As shown in FIG. 8B, in the second limiter pattern, the negative second threshold L2 is set to the reference threshold L. ₀₂ Set to a smaller (larger absolute value) constant value.
[0059]
By applying the second gain pattern and the second limiter pattern in the second traveling pattern, the torque command value T can be rapidly reduced when the speed deviation ε becomes negative. That is, it is possible to prevent the responsiveness of the vehicle speed v when the depression amount of the accelerator pedal 32 is reduced and to prevent unnecessary acceleration at the end of the uphill.
[0060]
The operation when the electric vehicle 10 enters the flat part after finishing the uphill will be described in detail with reference to FIG. In FIGS. 9 and 12 (to be described later), for the sake of simplicity, the torque required when traveling at a constant speed on a flat portion ignoring various frictions and air resistance generated during traveling is “0”. It is assumed that Further, the operation when the motor control method for the electric vehicle according to the present embodiment is applied is represented by a solid line, and the operation according to the related art is represented by a broken line.
[0061]
When the vehicle travels on an uphill with the amount of depression of the accelerator pedal 32 kept constant, the torque command value T maintains a positive value in order to cause the motor 14 to generate torque against the own weight of the electric vehicle 10. At this time, the speed deviation ε is substantially “0”, and the first traveling pattern or the second traveling pattern (see FIG. 5) is applied.
[0062]
When the vehicle enters the flat portion after the uphill, the required torque becomes “0”, while the torque command value T is a positive value and does not become “0” instantaneously. Therefore, the vehicle speed v increases even when the depression amount of the accelerator pedal 32 is kept constant.
[0063]
As the vehicle speed v increases, the speed deviation ε becomes negative, and the electric vehicle 10 travels in the second traveling pattern, and the second gain pattern and the second limiter pattern are applied. Accordingly, the gain G is set to a large value, and the second threshold L2 is set to a small value (large absolute value). Since the gain G is large, the integrator input a1 is set to a large value for a relatively small speed deviation ε, and is limited by the second threshold L2. As a result, the integrator output a2 and the torque command value T, which are the values obtained by integrating the integrator input a1 by the integrator 62, rapidly decrease to approach "0", thereby preventing the electric vehicle 10 from excessively accelerating. can do. Further, when the torque command value T passes through “0” and becomes a negative value, a third traveling pattern described later is reached, and the second threshold L2 is set to the reference threshold L. ₀₂ Since the absolute value increases (absolute value decreases), oscillation of the vehicle speed v can be prevented, and the vehicle can run in a stable state.
[0064]
In the operation when the conventional technique is applied (see the broken line), neither the gain G nor the second threshold L2 can be set to a large absolute value in order to prevent oscillation. Therefore, the torque command value T cannot be rapidly reduced in accordance with the speed deviation ε. As a result, even if the depression amount of the accelerator pedal 32 is constant, excessive acceleration occurs.
[0065]
As shown in FIG. 10A, in the third gain pattern, the gain G is proportionally increased from speed 0 to speed v3, and the reference gain value G ₀ Set to.
[0066]
As shown in FIG. 10B, in the third limiter pattern, the second threshold value L2 is proportionally reduced (increased in absolute value) from speed 0 to speed v4 based on a predetermined relatively large (small absolute value) value. Let it. In the range above the speed v4, the second threshold L2 is set to the reference threshold L ₀₂ Set to.
[0067]
In the third traveling pattern, a third gain pattern and a third limiter pattern are applied. Thus, when the electric vehicle 10 is decelerating at a high speed, for example, when the foot is released from the accelerator pedal 32, the gain G is relatively large. ₀ Therefore, the response of the torque command value T to the speed deviation ε is fast. Moreover, since the second threshold value L2 is set to a relatively small value (large absolute value) at the time of high-speed traveling, the electric vehicle 10 can be decelerated at an appropriate deceleration to shift to low-speed traveling.
[0068]
Further, when the electric vehicle 10 is traveling at a low speed and immediately before the stop, the absolute values of the gain G and the second threshold L2 are set to relatively small values, so that the response of the torque command value T to the speed deviation ε is set. , And the electric vehicle 10 can be slowly decelerated or stopped. When sudden braking is required, a brake pedal (not shown) may be used.
[0069]
As shown in FIG. 11A, in the fourth gain pattern, the gain G is changed to the reference gain value G ₀ Set to a larger constant value.
[0070]
As shown in FIG. 11B, in the fourth limiter pattern, the first threshold L1 is set to the reference threshold L ₀₁ Set to a larger constant value.
[0071]
By applying the fourth gain pattern and the fourth limiter pattern in the fourth traveling pattern, the torque command value T can be rapidly increased when the speed deviation ε becomes positive. In other words, it is possible to prevent the responsiveness of the vehicle speed v when the depression amount of the accelerator pedal 32 is increased and to prevent unnecessary deceleration at the end of the downhill.
[0072]
The operation when the electric vehicle 10 ends down the hill and enters the flat portion will be described in detail with reference to FIG.
[0073]
When traveling downhill with the amount of depression of the accelerator pedal 32 kept constant, the torque command value T is generated by generating a negative torque on the motor 14 in order to prevent the electric vehicle 10 from slipping down due to its own weight. It is carried out. At this time, the speed deviation ε is substantially “0”, and the third traveling pattern or the fourth traveling pattern (see FIG. 5) is applied.
[0074]
When the vehicle goes down the slope and enters the flat part, the required torque becomes “0”, while the torque command value T is a negative value and does not immediately become “0”. Therefore, the vehicle speed v is reduced even when the depression amount of the accelerator pedal 32 is kept constant.
[0075]
As the vehicle speed v decreases, the speed deviation ε becomes positive, and the electric vehicle 10 travels in the fourth travel pattern, and the fourth gain pattern and the fourth limiter pattern are applied. Therefore, the gain G is set to a large value, and the first threshold L1 is set to a large value. Because the gain G is large, the integrator input a1 is set to a large value for a relatively small speed deviation ε, and is limited by the first threshold L1. As a result, the integrator output a2 and the torque command value T, which are values obtained by integrating the integrator input a1 by the integrator 62, rapidly increase to approach "0", thereby preventing the electric vehicle 10 from being excessively decelerated. can do. When the torque command value T passes through “0” and becomes a positive value, the first running pattern is set, and the first threshold L1 is set to the reference threshold L. ₀₁ Therefore, oscillation of the vehicle speed v is prevented, and the vehicle can run in a stable state.
[0076]
In the operation when the conventional technique is applied (see the broken line), both the gain G and the first threshold L1 cannot be set to large values in order to prevent oscillation. Therefore, the torque command value T cannot be rapidly increased in accordance with the speed deviation ε. As a result, even if the depression amount of the accelerator pedal 32 is constant, the torque is excessively reduced.
[0077]
As described above, according to the motor control method for the electric vehicle according to the present embodiment, the gain G, the first threshold L1, and the second threshold L2 are generated in the limiter / gain setting unit 60 and the gain multiplication unit 56 Since the gain G is supplied and changed, and the first threshold L1 and the second threshold L2 are supplied and changed to the limiter 58, the speed deviation ε and the positive / negative of the torque command value T can be obtained even without a sensor for detecting the current I. Appropriate torque can be supplied according to the sign. Therefore, it is possible to accurately and promptly respond to the speed command value c converted from the depression amount of the accelerator pedal 32 and to run stably even when the load changes. Since the speed deviation ε is supplied to the torque command unit 64 via the gain multiplication unit 56, the limiter 58, and the integrator 62, the vehicle speed v serving as the reference of the speed deviation ε needs to have high resolution. There is no. Therefore, it is possible to use an inexpensive and low-resolution sensor of the Hall IC type or the like.
[0078]
Further, when the torque command value T and the speed deviation ε are both positive, that is, in the first traveling pattern, when the vehicle speed v is equal to or lower than the speed v1, the gain G is increased in proportion to the vehicle speed v, and the vehicle speed v becomes smaller than the speed v2. At this time, since the first threshold value L1 is reduced in proportion to the vehicle speed v, the response of the torque command value T to the speed deviation ε is smooth. In addition, at the time of start or low-speed running acceleration, the first threshold L1 is a relatively large value, for example, the reference threshold L ₀₁ , A large acceleration can be obtained.
[0079]
Furthermore, when the torque command value T is positive and the speed deviation ε is negative, that is, in the second traveling pattern, the gain G is changed to the reference gain value G. ₀ And the second threshold L2 is set to the reference threshold L ₀₂ Since the vehicle speed is further reduced, the responsiveness of the vehicle speed v when the depression amount of the accelerator pedal 32 is reduced, and unnecessary acceleration at the end of the uphill can be prevented.
[0080]
Further, according to the motor control method for the electric vehicle according to the present embodiment, when both torque command value T and speed deviation ε are negative and vehicle speed v is equal to or lower than speed v3, that is, in the third traveling pattern, The gain G is increased in proportion to the vehicle speed v, and when the vehicle speed v is equal to or less than the speed v4, the second threshold value L2 is decreased in proportion to the vehicle speed v. Therefore, the response of the torque command value T to the speed deviation ε becomes smooth, The electric vehicle 10 can be slowly decelerated or stopped.
[0081]
When the torque command value T is negative and the speed deviation ε is positive, that is, in the fourth traveling pattern, the gain G is changed to the reference gain value G. ₀ And the first threshold L1 is set to the reference threshold L ₀₁ Since it is further increased, the responsiveness of the vehicle speed v when the depression amount of the accelerator pedal 32 is increased, and unnecessary deceleration at the end of the downhill can be prevented.
[0082]
The first to fourth gain patterns and the first to fourth limiter patterns are not limited to those described above, and appropriate patterns can be adopted based on the speed deviation ε, the torque command value T, and the vehicle speed v.
[0083]
The motor control method of the electric vehicle according to the present invention is not limited to the above-described embodiment, but may adopt various configurations without departing from the gist of the present invention.
[0084]
【The invention's effect】
As described above, according to the motor control method for an electric vehicle according to the present invention, the sensor used for controlling the traveling motor is omitted or simplified, and the sensor responds accurately and quickly to the accelerator operation amount, and It is possible to achieve an effect that the vehicle can run stably even when it fluctuates.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a drive system of an electric vehicle.
FIG. 2 is a block diagram of an ECU and related devices.
FIG. 3 is a time chart showing changes in input / output signals of a speed command converter.
FIG. 4 is a flowchart illustrating an operation of a limiter / gain setting unit.
FIG. 5 is a schematic diagram showing four gain patterns and four limiter patterns on two-dimensional coordinates of a speed deviation and a torque command value.
FIG. 6 is a flowchart showing a procedure of a motor control method for the electric vehicle according to the present embodiment.
FIG. 7A is a graph showing a relationship between a gain and a vehicle speed in a first gain pattern, and FIG. 7B is a graph showing a relationship between a threshold value and a vehicle speed in a first limiter pattern.
FIG. 8A is a graph showing a relationship between a gain and a vehicle speed in a second gain pattern, and FIG. 8B is a graph showing a relationship between a threshold value and a vehicle speed in a second limiter pattern.
FIG. 9 is a time chart showing changes in a torque command value, a vehicle speed, a speed deviation, and an integrator input when the vehicle enters a flat portion from an uphill.
FIG. 10A is a graph showing a relationship between a gain and a vehicle speed in a third gain pattern, and FIG. 10B is a graph showing a relationship between a threshold value and a vehicle speed in a third limiter pattern.
FIG. 11A is a graph showing a relationship between a gain and a vehicle speed in a fourth gain pattern, and FIG. 11B is a graph showing a relationship between a threshold value and a vehicle speed in a fourth limiter pattern.
FIG. 12 is a time chart showing changes in a torque command value, a vehicle speed, a speed deviation, and an input of an integrator when the vehicle enters a flat portion from a downhill.
[Explanation of symbols]
10: electric vehicle 12: ECU
14 ... motor 32 ... accelerator pedal
34 ... Volume 38 ... Inverter
42 ... rotation angle detection sensor 52 ... speed command converter
54: subtraction point 56: gain multiplication unit
58: Limiter 60: Limiter / gain setting unit
62: integrator 64: torque command section
a1: Integrator input a2: Integrator output
c: Speed command value G: Gain
G ₀ ... Reference gain value I ... Current
L ₀₁ , L ₀₂ ... Reference threshold L1, L2 ... Threshold
T: Torque command value v: Vehicle speed
ε: Speed deviation θ: Angle signal

Claims (5)

Obtaining a first intermediate variable obtained by multiplying a gain by a deviation between a speed command value corresponding to an accelerator operation amount and a vehicle speed of the electric vehicle;
Obtaining the second intermediate variable by limiting the first intermediate variable to a range between a first positive threshold and a second negative threshold;
Generating a torque command value by integrating the second intermediate variable, and driving a driving motor in accordance with the torque command value;
Changing the gain, the first threshold value, and / or the second threshold value in accordance with a combination of the sign of the deviation and the sign of the torque command value, respectively;
A motor control method for an electric vehicle, comprising: The motor control method for an electric vehicle according to claim 1,
When the torque command value is positive, the deviation is positive, and the vehicle speed is equal to or less than a predetermined speed,
A motor control method for an electric vehicle, comprising: increasing the gain in proportion to the vehicle speed and decreasing the first threshold in proportion to the vehicle speed. The motor control method for an electric vehicle according to claim 1 or 2,
When the torque command value is positive and the deviation is negative,
A motor control method for an electric vehicle, comprising: increasing the gain from a reference gain value and decreasing the second threshold from a reference threshold. The motor control method according to any one of claims 1 to 3,
When the torque command value is negative, the deviation is negative, and the vehicle speed is equal to or less than a predetermined speed,
A motor control method for an electric vehicle, comprising: increasing the gain in proportion to the vehicle speed and decreasing the second threshold in proportion to the vehicle speed. The motor control method according to any one of claims 1 to 4,
When the torque command value is negative and the deviation is positive,
A motor control method for an electric vehicle, comprising: increasing the gain from a reference gain value and increasing the first threshold from a reference threshold.

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