JP3780504B2 - Electric vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an electric vehicle such as a battery forklift or an electric vehicle that travels by a travel motor that generates an output torque according to an operation amount of an accelerator using a battery as a drive source and performs braking by regenerative braking of the travel motor. .
[0002]
[Prior art]
In general, a battery forklift that is an electric vehicle is provided with a travel motor including, for example, an induction motor that uses a battery as a drive source, and a control device controls the output of the travel motor during power running to perform normal travel. On the other hand, at the time of braking, in addition to braking by the brake, the field current is controlled so that the traveling motor can be used as a generator, and regenerative braking that regenerates the energy generated at that time to the battery side is also performed. It has become.
[0003]
The braking of the battery forklift will be described in detail. There are two types of braking: mechanical braking and regenerative braking under the control of the control device.
(1) Braking that activates the foot brake,
(2) Braking that activates the side brake,
There is. In addition, as regenerative braking by the control of the latter control device,
(1) Downhill regenerative braking that regenerates so as not to accelerate when downhill.
(2) Neutral regenerative braking that regenerates to coast when there is no accelerator operation,
(3) Plugging regenerative braking when the direction of travel of the vehicle body is switched to the opposite direction by operation of the directional lever,
There is.
[0004]
And during braking, these braking functions are fully utilized to perform optimal braking according to the situation.
[0005]
[Problems to be solved by the invention]
However, in the case of conventional braking control, for example, when going down a hill, the foot brake pedal was fully depressed, but when the load of the loaded load changes, the braking characteristics of the foot brake will change. That is, if there is nothing loaded, the vehicle body is easily braked by the foot brake, but if the load of the loaded load is large, the vehicle body is not easily braked even if the foot brake pedal is fully depressed. Therefore, there is a problem that the driver cannot easily control the speed.
[0006]
In addition, when climbing a hill, the vehicle body slides down the hill before the accelerator is operated due to the load, so it is necessary to adjust the timing of the side brake and the accelerator when starting the hill. Stopping will cause the inconvenience of slipping down the slope.
[0007]
Furthermore, when stopping on a slope, it is necessary to operate the side brake or foot brake. In particular, if the operation of the side brake is forgotten, the vehicle body slips.
[0008]
Therefore, an object of the present invention is to provide an electric vehicle that enables deceleration or braking according to an accelerator operation amount by controlling regenerative braking.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a battery mounted on a vehicle body, and a travel motor that generates output torque in accordance with the amount of accelerator operation using the battery as a drive source. In a control apparatus for an electric vehicle that performs braking by braking, a target speed deriving unit that derives a target speed according to the amount of operation of the accelerator, a rotation detection unit that detects a rotation speed of the traveling motor, and the rotation detection unit A torque deriving unit for deriving an instruction torque such that a detected speed becomes the target speed, an operation unit for applying a desired limit to the instruction torque, and when the instruction torque by the torque deriving unit represents regeneration, And a control unit that controls the output of the travel motor by adding a limit corresponding to the operation of the operation unit to the instruction torque (Claim 1). .
[0010]
According to such a configuration, when the control unit determines that the command torque from the torque deriving unit represents regeneration, the limit according to the operation of the operation unit is added to the command torque, and the output of the travel motor is controlled. Is done. Therefore, for example, even when the accelerator operation is stopped in the middle of a slope, by limiting the instruction torque for regeneration by operating the operation unit, the state without the accelerator operation, that is, the speed is zero. Therefore, the vehicle body can be prevented from slipping down, so that deceleration or braking can be performed in accordance with the accelerator operation amount.
[0011]
Further, the present invention is characterized in that the control unit determines whether or not the command torque indicates regeneration based on the traveling direction of the vehicle body and the polarity of the command torque (claim 2). According to such a configuration, it can be accurately determined whether or not the indicated torque represents regeneration.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment when the present invention is applied to a counterbalance forklift will be described with reference to FIGS. 1 is a perspective view of a counterbalance forklift, FIG. 2 is a block diagram of a control device, FIG. 3 is an operation explanatory diagram, and FIG. 4 is a flowchart for explaining the operation.
[0013]
The counterbalance forklift in this embodiment is configured as shown in FIG. 1, for example. That is, a battery (not shown) is mounted and accommodated below the seat 2 provided in the driver's seat of the vehicle body 1, and a power is supplied to a travel motor and a hydraulic motor (not shown) by this battery. These motors are driven, and in response to depression of the accelerator pedal 3, the travel motor is driven based on an output command value from a control device, which will be described later, in the forward or reverse direction set by the tilting operation of the directional lever 4. The vehicle body 1 travels. Incidentally, 5 is a steering handle, and 6 is a foot brake pedal.
[0014]
Further, as shown in FIG. 1, a mast 8 is telescopically attached to the front portion of the vehicle body 1, and a pair of L-shaped forks 10 are attached to the mast 8 via a lift bracket 9. Then, by operating the lift lever 12 provided in the driver's seat, the hydraulic motor is driven based on the output command value from the control device, the lift cylinder is operated and the mast 8 is expanded and contracted. Goes up and down. In addition to the lift lever 12, the driver's seat is provided with a tilt lever 14. By operating the tilt lever 14, the tilt cylinder is operated, the mast 8 is tilted, and the fork 10 is tilted together with the mast 8. To do.
[0015]
Further, as shown in FIG. 1, the driver's seat is provided with a limit pedal 16 for torque limiting operation that constitutes an operating portion and is operated with the left foot, and an operation amount (depression amount) of the limiting pedal 16 is, for example, It is detected by a detector composed of a potentiometer (not shown in FIG. 1).
[0016]
Next, the configuration of the control device will be described with reference to the block diagram of FIG. As shown in FIG. 2, the depression amount (operation amount) of the accelerator pedal 3 is detected by an accelerator sensor 22 composed of a potentiometer, for example, and a target speed corresponding to the depression amount detected by the accelerator sensor 22 is derived by the CPU 21. The actual running speed is obtained by the CPU 21 from the rotation speed of the running motor 24 detected by the pulse generator 23 as the rotation detecting unit, and the running motor 24 is matched with the target speed by the PID control. The command torque is derived, and the PWM inverter 25 is controlled according to the derived command torque, and the output control of the travel motor 24 is performed. However, the actual traveling speed may be detected by an encoder provided on the wheel.
[0017]
Here, the target speed deriving process by the CPU 21 corresponds to the target speed deriving section in the present invention, and the instruction torque deriving process corresponds to the torque deriving section in the present invention.
[0018]
Further, as shown in FIG. 2, the depression amount of the limit pedal 16 detected by a detector 27 comprising a potentiometer provided on the limit pedal 16 is input to the CPU 21, whereby the CPU 21 regenerates the derived instruction torque. When expressing, the limit amount is derived within the range from zero to the maximum value in accordance with the depression amount of the limit pedal 16, and to what extent the indicated torque is permitted is determined based on the limit amount, and the permitted torque is derived and derived. The output control of the traveling motor 22 is performed according to the permitted torque. At this time, when the limit pedal 16 is not depressed, the limit amount with respect to the instruction torque for regeneration becomes maximum and the permitted torque becomes zero or minimum. When the limit pedal 16 is depressed, the instruction for regeneration It is desirable that the limit amount for the torque is set to zero and the permitted torque is maximized.
[0019]
The CPU 21 determines whether or not the command torque indicates regeneration based on the traveling direction of the vehicle body 1 set by operating the directional lever 4 and the polarity of the derived command torque. Specifically, in the graph showing the relationship between the command torque and the speed command shown in FIG. 3, when the first quadrant is forward and the third quadrant is reverse, the polarity of the command torque is changed when the vehicle body 1 is in the forward state. If it is negative, the command torque at that time is a torque representing regeneration. Conversely, in the case of reverse travel, if the polarity of the command torque is positive, it is determined that the command torque is a torque representing regeneration. .
[0020]
Further, as the regenerative braking function of the CPU 21, the downhill regenerative function that regenerates so as not to accelerate during downhill, the neutral regenerative function that regenerates so as to coast when there is no accelerator operation, and the traveling direction of the vehicle body 1 are in opposite directions. A regenerative torque required for regeneration in each of these regenerative functions, for example, the current motor rotation speed by the pulse generator 23. The calculated regenerative torque and the permitted torque are compared, and the output having the largest absolute value is adopted to control the output of the travel motor 22. Such instruction torque limiting processing by the CPU 21 corresponds to the control unit in the present invention.
[0021]
Next, a series of operations will be described with reference to the flowchart of FIG. 4. First, as shown in FIG. 4, initial setting is first performed (S1), and the CPU 21 depresses the accelerator pedal 3 by the accelerator sensor 22, and The operation direction of the directional lever 4 is taken in (S2), and the depression amount of the limit pedal 16 by the detector 27 is taken in (S3).
[0022]
Then, the CPU 21 derives the target speed based on the amount of the accelerator pedal 3 that has been taken in and the operation direction of the directional lever 4 (S4), and the actual speed is calculated from the rotational speed of the travel motor 24 detected by the pulse generator 23. Is calculated (S5), and the command torque of the travel motor 24 is derived so that the actual travel speed matches the target speed by PID control (S6).
[0023]
Thereafter, it is determined whether or not the derived instruction torque indicates regeneration (S7). If the determination result is YES, that is, if it is determined that the instruction torque indicates regeneration, the depression amount of the limit pedal 16 by the detector 27 is determined. Based on the above, the command torque derived in step S6 is limited to derive the permitted torque (S8), and the command torque and permitted torque derived in step S6 having the smaller absolute value is adopted as the command torque ( S9), regenerative torque required for descending slope regeneration, neutral regeneration, plugging regeneration, and maximum speed regeneration is calculated (S10), and the calculated regenerative torque and the instruction torque adopted in step S9 have a large absolute value. Is adopted as the output torque (S11), and then the process proceeds to step S13.
[0024]
On the other hand, if the determination result in step S7 is NO, that is, if it is determined that the instruction torque does not represent regeneration, the derived instruction torque is used as the output torque as it is (S12), and then the process proceeds to step S13. The output torque in S11 or the output torque in step S12 is output as a torque command value to the PWM inverter 25 to perform output control of the traveling motor 24 (S13), and then the process returns to step S2.
[0025]
Therefore, according to the above-described embodiment, when the CPU 21 determines that the derived command torque represents regeneration, the command torque is limited in accordance with the depression amount of the limit pedal 16, and the permitted torque is derived. Since the output of the motor 24 is controlled, deceleration or braking according to the depression amount of the accelerator pedal 3 can be performed.
[0026]
As a result, for example, when going down a slope, if the depressing pedal 16 is depressed, a constant braking force can be generated regardless of the load without depressing the foot brake pedal 6 fully. It is possible to easily control the vehicle body 1 to a desired speed corresponding thereto.
[0027]
Further, when climbing a hill, if the allowable torque is optimally limited by adjusting the amount of depression of the limit pedal 16, the vehicle body can be adjusted without performing the so-called side alignment that matches the timing of the side brake and the accelerator as in the prior art. 1 can climb up without sliding down.
[0028]
Further, when stopping on the slope, if the limit pedal 16 is fully depressed, the vehicle body 1 is slipped by stopping the depression of the accelerator pedal 3 without operating the side brake or the foot brake pedal 6. It can be stopped without
[0029]
Further, even when driving on a flat road, if the driver desires to travel as usual according to his / her preference, the permitted torque is zero unless the limit pedal 16 is depressed, and for example, the depression of the accelerator pedal 3 is stopped. Then, the vehicle body 1 coasts on a flat road, and the driver can drive without discomfort with the same driving feeling as before.
[0030]
In the above-described embodiment, the case where the permitted torque is set to be zero or minimum when the limit pedal 16 is not depressed and the permitted torque is maximized when the limit pedal 16 is depressed is described. On the contrary, the permitted torque may be set to be maximum when the limit pedal 16 is not depressed, and may be set to be zero or minimum when the limit pedal 16 is depressed. .
[0031]
In the above-described embodiment, the case of having four of the descending slope regeneration function, the neutral regeneration function, the plugging regeneration function, and the fastest regeneration function is described, but it is not always necessary to provide these four regeneration functions, and at least the descending regeneration function is provided. What is necessary is just to have three functions of a slope regeneration function, a neutral regeneration function, and a plugging regeneration function.
[0032]
Further, in the above-described embodiment, the case where the present invention is applied to the counterbalance type forklift has been described. However, other than the counterbalance type, the applicable range of the present invention is other forklifts including a reach type forklift, other Needless to say, the present invention can be applied to all electric vehicles such as electric vehicles, and in this case, the same effect as the above-described embodiment can be obtained.
[0033]
In particular, when applied to a standing type such as a reach type forklift, the permitted torque is maximized when the operating device such as the limiting pedal 16 is not operated due to the configuration of the standing type, and the operation of the limiting pedal 16 or the like is performed. It is preferable to set the allowable torque to be zero or minimum when the device is operated.
[0034]
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.
[0035]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the control unit determines that the command torque from the torque deriving unit represents regeneration, a restriction according to the operation of the operation unit is added to the command torque. Because the output of the traveling motor is controlled, for example, even when the accelerator operation is stopped in the middle of a hill, by applying a restriction that maximizes the instruction torque for regeneration by operating the operation unit, It is possible to prevent the vehicle body from slipping by maintaining the state without the accelerator operation, that is, the stop state where the speed becomes zero. Therefore, it is possible to provide an electric vehicle that can perform deceleration or braking according to the accelerator operation amount.
[0036]
In addition, according to the second aspect of the present invention, it is possible to accurately determine whether or not the indicated torque represents regeneration.
[Brief description of the drawings]
FIG. 1 is a perspective view of a counterbalance forklift according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control device according to an embodiment of the present invention.
FIG. 3 is an operation explanatory diagram of one embodiment of the present invention.
FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention.
[Explanation of symbols]
1 Body 3 Accelerator pedal 16 Pedal (operating part)
21 CPU (target speed deriving unit, torque deriving unit, control unit)
22 Accelerator sensor 23 Pulse generator (rotation detector)
24 Traveling motor 27 Detector

Claims (2)

  In a control device for an electric vehicle, comprising: a battery mounted on a vehicle body; and a travel motor that generates an output torque according to an operation amount of an accelerator using the battery as a drive source, and performs braking by regenerative braking of the travel motor. A target speed deriving unit for deriving a target speed according to the amount of operation of the accelerator, a rotation detection unit for detecting the rotation speed of the travel motor, and an instruction torque for causing the detection speed by the rotation detection unit to be the target speed. A torque deriving unit for deriving, an operation unit for applying a desired limit to the command torque, and when the command torque by the torque deriving unit represents regeneration, a limit corresponding to the operation of the operation unit is set to the command torque And a control unit for controlling the output of the travel motor.   The control device for an electric vehicle according to claim 1, wherein the control unit determines whether or not the command torque indicates regeneration based on a traveling direction of the vehicle body and a polarity of the command torque.

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