JP2015089700A - Motor driving device for forklift and electric forklift using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress hunting in a dual motor type electric forklift.SOLUTION: A speed distribution unit 200 calculates a left speed command value Vlref for instructing a speed of a left travel motor and a right speed command value Vrref for instructing a speed of a right travel motor, based on an input speed command value Vref according to an operation of an operator and a steering angle δof a steering wheel of an electric forklift. A torque command value generating unit 202 generates torque command values Tlcom, Trcom for instructing the torque of left and right travel motors based on the left speed command value Vlref and the right speed command value Vrref. A range in which a rotation center of the electric forklift overlaps with a driving wheel is defined as a hunting region. When the steering angle δis included in a dead zone provided corresponding to the hunting region, a motor driving device 300 makes at least one of the speed command value and the torque command value with respect to the driving wheels on the inner wheel side substantially zero.

Description

  The present invention relates to a motor drive device for a forklift.

  One of the industrial vehicles is an electric forklift that uses a battery as a power source. An electric forklift (hereinafter simply referred to as a forklift) is a traveling motor that transmits power to a front wheel that is a traveling wheel (driving wheel) and a hydraulic pump that controls a turning angle (steering angle) of a rear wheel that is a steered wheel. Hydraulic actuator motor (steering motor) that transmits power, hydraulic actuator motor (loading motor) that transmits power to the hydraulic pump that controls the lifting body, and power conversion that drives each of the travel motor, steering motor, and cargo handling motor Equipment.

  As a result of studying a dual motor type electric forklift in which independent motors are provided for each of the right driving wheel and the left driving wheel and the respective rotation speeds and rotation directions can be controlled independently, the following problems have been solved. It came to recognize.

  The rotation center (turning center) of the electric forklift provided with the Ackermann linkage mechanism moves on a virtual extension line of the shaft of the drive wheel according to the turning angle. In the dual motor type electric forklift, when the turning radius decreases as the turning angle increases, the center of rotation enters the inside of both drive wheels. In this state, the driving wheel on the inner ring side rotates in the opposite direction to the driving wheel on the outer ring side.

  Theoretically, the rotation direction of the drive wheel on the inner ring side should be opposite in the part outside the rotation center of the drive wheel and in the inner part, but the tire is a rigid body, so it rotates only in one direction. do not do. Therefore, for example, the speed of the inner driving wheel is determined so that the rotation direction is reversed when the turning radius is located approximately at the center of the inner driving wheel.

  Here, if the center of rotation frequently moves so as to straddle substantially the center of the drive wheel, the rotation direction of the inner drive wheel frequently changes back and forth, and the behavior of the vehicle body becomes unstable. In this specification, this is called hunting.

  The present invention has been made in such a situation, and one of the exemplary purposes of an embodiment thereof is to provide a motor driving device capable of suppressing hunting in a dual motor type electric forklift.

  An aspect of the present invention includes a left traveling motor and a right traveling motor that are mounted on an electric forklift and transmit power to each of a left driving wheel and a right driving wheel of the electric forklift based on a speed command value indicating a target speed of the electric forklift. The present invention relates to a motor drive device to be controlled. The motor drive device instructs a left speed command value for instructing the speed of the left travel motor and a speed of the right travel motor based on the input speed command value according to the operation of the driver and the turning angle of the steered wheels of the electric forklift. A speed distribution unit that calculates a right speed command value, and generates a left torque command value that indicates the torque of the left traveling motor according to an error between the left speed command value and the current speed of the left traveling motor, and the right speed command A torque command value generation unit that generates a right torque command value that indicates the torque of the right traveling motor in accordance with an error between the value and the current speed of the right traveling motor. In this motor drive device, when the turning angle is included in a dead zone provided corresponding to a range in which the rotation center of the electric forklift overlaps with the drive wheel, a speed command value and a torque command value for the drive wheel on the inner ring side At least one of them is substantially zero.

  According to this aspect, when the center of rotation is at a position where hunting can occur, control can be performed so as to stop the rotation of the inner driving wheel, thereby preventing hunting.

  The speed distribution unit may set the speed command value for the driving wheel on the inner wheel side to substantially zero when the turning angle is included in the dead zone.

  The speed distribution unit defines a function that uses the turning angle as an argument. During turning, the speed command value of the driving wheel on the outer wheel side is set as the input speed command value, and the speed command value of the inner wheel side driving wheel is set. Is set to a value obtained by multiplying the input speed command value by the value of the function, and the function may be determined such that when the turning angle is included in the dead zone, the value is substantially zero.

  The motor drive device according to one aspect limits the left torque command value to an upper limit value or less according to the rotation speed of the left drive wheel, and limits the right torque command value to an upper limit value or less according to the rotation speed of the right drive wheel. A torque limit unit may be further provided. When the turning angle is included in the dead zone, the torque limit unit may set the torque command value for the driving wheel on the inner ring side to substantially zero.

  Even if the speed command value for the inner drive wheel is substantially zero, if the detected speed value is non-zero, the torque command value will be non-zero and torque will be generated in the inner drive wheel. Hunting may occur. According to this aspect, hunting can be more reliably prevented by making the torque command value substantially zero.

  Another embodiment of the present invention is also a motor driving device. This motor drive device is mounted on an electric forklift, and a left traveling motor and a right traveling that transmit power to each of the left and right driving wheels of the electric forklift based on a torque command value indicating a target torque of the driving wheels of the electric forklift. Control the motor. The motor drive device instructs a left torque control value for instructing the torque of the left traveling motor and a torque of the right traveling motor based on the input torque control value according to the operation of the driver and the turning angle of the steered wheel of the electric forklift. A torque distribution unit that calculates a right torque control value, and generates a left torque command value that indicates the torque of the left traveling motor in accordance with an error between the left torque control value and the current torque of the left traveling motor, and the right torque control A torque command value generation unit that generates a right torque command value that indicates the torque of the right traveling motor according to an error between the value and the current torque of the right traveling motor. The range in which the rotation center of the electric forklift overlaps with the drive wheel is defined as the hunting region, and when the turning angle is included in the dead zone provided corresponding to the hunting region, the torque control value and torque for the drive wheel on the inner ring side At least one of the command values is substantially zero.

  According to this aspect, when the center of rotation is at a position where hunting can occur, control can be performed so as to stop the rotation of the inner driving wheel, thereby preventing hunting.

  When the turning angle is included in the dead zone, the torque distribution unit may set the torque control value for the drive wheel on the inner wheel side to substantially zero.

  The torque distribution unit has a function that defines the turning angle as an argument. During turning, the torque control value of the driving wheel on the outer wheel side is set to the input torque control value, and the torque control value of the driving wheel on the inner wheel side is set. Is set to a value obtained by multiplying the input torque control value by the value of the function, and the function may be determined such that when the turning angle is included in the dead zone, the value is substantially zero.

  The motor drive device according to one aspect limits the left torque command value to an upper limit value or less according to the rotation speed of the left drive wheel, and limits the right torque command value to an upper limit value or less according to the rotation speed of the right drive wheel. A torque limit unit may be further provided. When the turning angle is included in the dead zone, the torque limit unit may set the torque command value for the driving wheel on the inner ring side to substantially zero.

  Another aspect of the present invention relates to an electric forklift. The electric forklift includes a left driving wheel and a right driving wheel, a left traveling motor and a right traveling motor that transmit power to the left driving wheel and the right driving wheel, and the motor driving device described above that drives the left traveling motor and the right traveling motor. And comprising.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, hunting can be suppressed in a dual motor type electric forklift.

It is a perspective view which shows the external view of the electric wheel forklift of a front wheel drive and a rear-wheel steering type. It is a figure which shows an example of the control panel of a forklift. It is a block diagram which shows the structure of the electric system of a dual motor type forklift, and a mechanical system. FIGS. 4A and 4B are views schematically showing a dual motor type forklift. It is a block diagram of the motor drive device concerning an embodiment. FIGS. 6A and 6B are diagrams illustrating the relationship between the dead zones Δθ _DL and Δθ _DR during left turn and right turn and the hunting region. FIGS. 7A to 7C are diagrams showing the functions g _LH (δ _r ) and g _RH (δ _r ). FIG. 8 is a block diagram of a motor drive device according to a second modification.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

  FIG. 1 is a perspective view showing an external view of a front wheel drive and rear wheel steering type electric forklift. The forklift 600 includes a vehicle body (chassis) 602, a fork 604, an elevating body (lift) 606, a mast 608, a front wheel 610 as a driving wheel, and a rear wheel 612 as a steering wheel (steering wheel). The mast 608 is provided in front of the vehicle body 602. The lifting body 606 is driven by a power source such as a hydraulic actuator (not shown in FIG. 1, 116 in FIG. 3) and moves up and down along the mast 608. A fork 604 for supporting a load is attached to the elevating body 606.

  FIG. 2 is a view showing an example of a control panel 700 of a forklift. The control panel 700 includes an ignition switch 702, a steering wheel 704, a lift lever 706, an accelerator pedal 708, a brake pedal 710, a dashboard 714, and a forward / reverse lever 712.

  The ignition switch 702 is a switch for starting the forklift 600. The steering wheel 704 is an operation means for steering the forklift 600. The lift lever 706 is an operation means for moving the elevating body 606 up and down. The accelerator pedal 708 is an operating means that controls the rotation of the traveling wheels, and the travel of the forklift 600 is controlled by the driver adjusting the amount of depression. When the driver depresses the brake pedal 710, the brake is applied. The forward / reverse lever 712 is a lever for switching the traveling direction of the forklift 600 between forward and reverse. In addition, an inching pedal (not shown) may be provided.

  Next, the configuration of the forklift 600 will be described for traveling, cargo handling, and steering. FIG. 3 is a block diagram showing a configuration of an electric system and a mechanical system of the dual motor type forklift 600. The ECU (electronic control controller) 110 is a processor for controlling the forklift 600 as a whole.

Battery 106 outputs battery voltage V _BAT between P line and N line.
The first power conversion device 100, the second power conversion device 102, and the third power conversion device 104 constitute a motor drive device 300. Motor drive device 300 drives travel motors M1L, M1R, cargo handling motor M2, and steering motor M3 based on first control command value S1 to third control command value S3 from ECU 110, respectively. The first power conversion device 100, a second power converter 102, respectively the third power converter 104 receives the battery voltage _{V BAT,} is converted into three-phase alternating current signal, the corresponding motor M1L, the M1R, M2, M3 Supply.

(Running)
The ECU 110 receives a signal for instructing forward and backward from the forward / reverse lever 712 and a signal indicating a travel operation amount corresponding to the depression amount from the accelerator pedal 708, and receives a first control command value S1 corresponding to the first control command value S1 as a first value. It outputs to the power converter 100. The first power conversion device 100 controls the power supplied to each of the left traveling motor M1L and the right traveling motor M1R according to the first control command value S1. The first control command value S1 has a correlation with the speed command value that instructs the target speed of the traveling motor M1. The left front wheel (left drive wheel) 610L, which is a drive wheel, is rotated by the power of the left travel motor M1L, and the right front wheel (right drive wheel) 610R is rotated by the power of the right travel motor M1R.

(Handling)
The vertical movement of the elevating body 606 is controlled by the inclination of the lift lever 706. The ECU 110 detects the tilt of the lift lever 706 and outputs a second control command value S <b> 2 indicating a cargo handling operation amount corresponding to the tilt to the second power conversion device 102. The second power converter 102 supplies power corresponding to the second control command value S2 to the cargo handling motor M2, and controls its rotation. The elevating body 606 is connected to the hydraulic actuator 116. The hydraulic actuator 116 converts the rotary motion generated by the cargo handling motor M2 into a linear motion and controls the lifting body 606.

(steering)
The encoder 122 detects the rotation angle of the steering wheel 704 and outputs a signal indicating the rotation angle to the ECU 110. ECU 110 outputs third control command value S3 corresponding to the rotation angle to third power conversion device 104. The third power converter 104 supplies power corresponding to the third control command value S3 to the steering motor M3, and controls the number of rotations thereof. A rear wheel 612 that is a steered wheel is connected to a gear box 124 via a tie rod 126. The rotational motion of the steering motor M3 is transmitted to the tie rod 126 via the hydraulic actuator 118 and the gear box 124, and the steering is controlled.

  4 (a) and 4 (b) are diagrams schematically showing a dual motor type forklift 600. FIG. L is the wheel base, Trf is the front tread, Trr is the rear tread, nl (rpm) is the rotation speed of the left drive wheel 610L, nr (rpm) is the rotation speed of the right drive wheel 610R, and Vl (m / s) is The speed detection value (wheel speed) of the left driving wheel 610L and Vr (m / s) indicate the speed detection value (wheel speed) of the right driving wheel 610R.

The turning angles of the rear wheels 612L and 612R which are steered wheels can be controlled by the Ackerman steering mechanism. Rear wheels 612L, 612R is the intersection of the respective axle body of the rotation center O, and the rotation center O in accordance with the steering angle [delta] _r, moves the front wheels 610L, the upper shaft of the 610R on the left and right. In the present embodiment, the turning angle δ _r is defined as the rotation angle of the right rear wheel, but those skilled in the art understand that the definition of the turning angle δ _r is not limited thereto. The steered angle δ _r is positive when turning left as shown in FIG. 4 (a) and negative when turning right as shown in FIG. 4 (b).
[rho _x is the rotation center O, the front wheels 610L, the distance of the midpoint of 610R.

  The steering mechanism of the forklift 600 allows the rotation center O to move between the front wheels 610L and 610R. In this case, the left and right drive wheels 610L and 610R are controlled to rotate in the reverse direction. Specifically, the outer driving wheel rotates in the traveling direction, and the inner driving wheel rotates in the opposite direction.

  FIG. 5 is a block diagram of travel motor drive apparatus 300 according to the embodiment. The motor driving device 300 corresponds to the first power conversion device 100 of FIG.

  The motor driving device 300 includes a speed distribution unit 200, a torque command value generation unit 202, a torque limit unit 208, an inverter 210, a speed sensor 220, a rotation speed / speed (n / V) converter 221L, 221R, and a turning angle sensor 222. .

The turning angle sensor 222 detects a turning angle δ _r shown in FIG. The speed sensor 220 is also called a resolver, and detects the rotational speeds nl and nr of the left traveling motor M1L and the right traveling motor M1R. The n / V converters 221L and 221R multiply the rotational speeds nl and nr by a coefficient corresponding to the tire circumference, the reduction gear ratio, and the like, so that the wheel speed Vl of the left drive wheel 610L and the right drive wheel 610R The wheel speed Vr is calculated.

The speed distribution unit 200 receives an input speed command value Vref corresponding to the accelerator operation amount. Speed distribution unit 200, depending on the current turning angle [delta] _r, computes the left velocity command value Vlref a target speed left travel motor M1L, the right velocity command value Vrref a target speed of right travel motor M1R .

Specifically, the speed distribution unit 200 sets the speed command value for the outer driving wheel to the input speed command value Vref, sets the speed command value for the inner driving wheel to the input speed command value Vref, and turns the steering angle δ. Set to a value multiplied by a coefficient corresponding to _r . That is, this coefficient is the ratio of the speed of the inner drive wheel to the outer drive wheel.

The coefficient is determined as a function g (δ _r ) of the turning angle δr. This function g (δ _r ) may be determined based on the steering mechanism and the geometry of the vehicle body.

  Hereinafter, speed distribution will be described with respect to the forklifts shown in FIGS.

1. δ _r = 0 (straight)
When traveling straight, the speed command values Vlref and Vrref for the left and right drive wheels are both set to the input speed command value Vref.
Vlref = Vrref = Vref

2. δ _r > 0 (turn left)
Vrref = Vref
Vlref = g _L (δ _r ) × Vref
The function g _L (δ _r ) at the time of turning left is given by the following equation.
g _L (δ _r ) = (ρ _x −Trf / 2) / (ρ _x + Trf / 2)
However, it is (rho) _x = L / tan ((delta) _r ) -Trr / 2.

3. δ _r <0 (turn right)
Vrref = g _R (δ _r ) × Vref
Vlref = Vref
The function g _R (δ _r ) at the time of turning right is given by the following equation.
g _R (δ _r ) = (ρ _x −Trf / 2) / (ρ _x + Trf / 2)
However, when δ _r ≠ −π / 2, ρ _x = −L / tan (δ _r ) + Trr / 2, and when δ _r = −π / 2, ρ _x = Trr / 2.

  The torque command value generation unit 202 generates a left torque command value Tlcom that indicates the torque of the left traveling motor M1L according to the error between the left speed command value Vlref and the current detected speed value Vl of the left traveling motor M1L. Similarly, a right torque command value Trcom instructing the torque of the right travel motor M1R is generated according to the error between the right speed command value Vrref and the current speed detection value Vr of the right travel motor M1R.

  Torque command value generation unit 202 performs subtractor 204L that generates an error between left velocity command value Vlref and left velocity detection value Vl, and PI control that generates a left torque command value Tlcom by performing PI (proportional, integral) control on the error. Part 206L. The same applies to the right wheel.

  In the torque limit unit 208, a torque limit curve Tlim (n) that defines the upper limit value Tlim of the torque command values Tlcom and Trcom is defined as a function of the motor speed n.

  The torque limit unit 208 limits the left torque command value Tlcom to an upper limit value Tllim which is determined according to the current speed nl of the left traveling motor M1L and the torque limit curve Tlim (n). Similarly, the torque limit unit 208 limits the right torque command value Trcom to an upper limit value Trlim determined according to the current speed nr of the right traveling motor M1R and the torque limit curve Tlim (n). The torque limit curve Tlim (n) may be held as a table or may be held as an approximate expression.

A range where the rotation center O of the electric forklift overlaps with the drive wheels is defined as a hunting region. The hunting area may coincide with the width of the drive wheel or may be set slightly wider than the width of the drive wheel.
When the turning angle δ _r is included in the dead zone provided corresponding to the hunting region, the motor driving device 300 hunts at least one of the speed command value Vref and the torque command value Tcom for the driving wheel on the inner ring side. A value that does not occur. More specifically, when the turning angle δ _r is included in the dead zone, the motor drive device 300 sets at least one of the speed command value Vref and the torque command value Tcom for the drive wheels on the inner ring side to be substantially zero. . That is, “substantially zero” is an example of “a value at which hunting does not occur”, and “substantially zero” is a value in which the speed command value or the torque command value is zero or in the vicinity thereof. , Including preventing the driving wheel on the inner ring side from reacting to the speed command value or preventing the driving wheel from reversing the driving direction.

FIGS. 6A and 6B are diagrams illustrating the relationship between the dead zones Δθ _DL and Δθ _DR during left turn and right turn and the hunting region. The hunting area is indicated by rectangles 52 and 54. Rotational center O moves in accordance with the steering angle [delta] _r, the steering angle [delta] _r when the rotation center O is included in the rectangular 52 becomes a dead zone [Delta] [theta] _DL during left turning. Similarly, the turning angle δ _r when the center of rotation is included in the rectangle 54 is a dead zone Δθ _DR when turning right.

  For example, when the turning angle δr is included in the dead zone, the speed distribution unit 200 sets the speed command value Vref for the driving wheel on the inner wheel side to substantially zero.

As described above, the functions g _L (δ _r ) and gR (δ _r ) having the turning angle δ _r as an argument are defined in the speed distribution unit 200. At the time of turning, the speed distribution unit 200 sets the speed command value of the driving wheel on the outer wheel side to the input speed command value Vref, and sets the speed command value of the driving wheel on the inner wheel side to the input speed command value Vref as a function value. Set to a value obtained by multiplying by g (δ _r ). In the present embodiment, in order to prevent hunting, the above-described functions g _L (δ _r ) and g _R (δ _r ) are set to zero when the turning angle δ _r is included in the dead zone. The corrected functions g _LH (δ _r ) and g _RH (δ _r ) are determined.

FIGS. 7A to 7C are diagrams showing the functions g _LH (δ _r ) and g _RH (δ _r ). Dashed lines indicate functions g _L (δ _r ) and g _R (δ _r ) before correction. FIG. 7B shows an enlarged view of the function g _LH (δ _r ) near the dead zone Δθ _DL , and FIG. 7C shows an enlarged view of the function g _RH (δ _r ) near the dead zone Δθ _DR . It is.

In the dead zone, the functions g _LH (δ _r ) and g _RH (δ _r ) are zero. A transition zone Δθ _{T is} provided outside the dead zone. In the transition band Δθ _T , the functions g _LH (δ _r ) and g _RH (δ _r ) increase with respect to the functions g _L (δ _r ) and g _R (δ _r ) before correction as they move away from the dead band Δθ _D. Gradually asymptotically. The functions g _LH (δ _r ) and g _RH (δ _r ) in the transition band Δθ _T may be straight lines.

Returning to FIG. When the turning angle δ _r is included in the dead zone Δθ _D , the torque limit unit 208 sets the torque command value Tref for the driving wheel on the inner ring side to zero.

  The above is the configuration of the motor driving device 300. Next, the operation will be described.

With reference to FIG. 6A and FIG. 7B, the case of left turn will be described. For example, when the forklift 600 is desired to make a sudden left turn, the turning angle δ _r increases. As a result, the rotation center O approaches the vehicle body center. When the rotation center O approaches the hunting region 52, the turning angle δ _r enters the transition band Δθ _T in FIG. 7B, and the coefficient (right / left speed ratio) decreases according to the function g _LH (δ _r ). The speed command value for the inner drive wheel begins to decrease. When the turning angle δ _r enters the dead zone Δθ _DL , the coefficient (right / left speed ratio) becomes zero, and the speed command value for the inner drive wheel becomes zero.

  The torque limit unit 208 also sets the torque command value Tref for the dead zone Δθ inner drive wheel to zero.

The above is the operation of the motor driving device 300.
According to the forklift 600 equipped with the motor driving device 300, even if the turning angle δ _r changes within the dead zone Δθ _D , the rotation speed of the inner driving wheel is maintained at zero, so that hunting is suppressed. Can do.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. is there. Hereinafter, such modifications will be described.

(First modification)
In the embodiment, the case where the correction of the speed command value in the speed distribution unit 200 and the correction of the torque command value by the torque limit unit 208 are used together is described. However, the present invention is not limited to this, and only one of them is corrected. Corrections may be employed.

(Second modification)
In the embodiment, the motor drive device 300 that controls the speed of the forklift 600 based on the speed command value has been described, but the present invention is not limited thereto.
For example, the motor driving device 300 controls a left traveling motor and a right traveling motor that transmit power to each of the left driving wheel and the right driving wheel of the electric forklift based on a torque command value indicating a target torque of the driving wheel of the electric forklift. Also good.

FIG. 8 is a block diagram of a motor driving device 300a according to the second modification.
A motor drive device 300a in FIG. 8 includes a torque distribution unit 200a and a torque command value generation unit 202a instead of the speed distribution unit 200 and the torque command value generation unit 202 in FIG.
The torque distributor 200a receives the input torque control value Tref corresponding to the driver's operation as the first control command value S1. Torque distribution unit 200a, based on the steering angle [delta] _r of the steered wheels of the input torque control value Tref and the electric forklifts, and instructs the torque of the left torque control value Tlref and the right travel motor M1R instructing the torque of the left travel motor M1L The right torque control value Trref is calculated. The calculation algorithm is the same as that of the speed distribution unit.

  The torque command value generation unit 202 generates a left torque command value Tlcom for instructing the torque of the left traveling motor according to an error between the left torque control value Tlref and the current torque Tl of the left traveling motor, and a right torque control value. A right torque command value Trcom that indicates the torque of the right traveling motor is generated in accordance with an error between Trref and the current torque Tr of the right traveling motor.

In this motor driving apparatus 300a, the turning angle [delta] _r is, when included in the dead zone [Delta] [theta] _D provided corresponding to the hunting area, at least one of the torque control value Tref and the torque command value Tcom for driving wheels of the inner ring side Is substantially zero.

  Control of the torque control value Tref by the torque distributor 200a is the same as that of the speed distributor 200 of FIG. Control of torque command value Tcom in torque limit unit 208 is the same as control of torque command value Tref in torque limit unit 208 of FIG.

This modification can also suppress hunting. Also, in the dead zone Δθ _D , only one of the torque command value Tcom and the torque command value Tref may be substantially zero.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 600 ... Forklift, 602 ... Car body, 604 ... Fork, 606 ... Lifting body, 608 ... Mast, 610 ... Front wheel, 612 ... Rear wheel, 106 ... Battery, 100 ... First power converter, 102 ... Second power converter, DESCRIPTION OF SYMBOLS 104 ... 3rd power converter device, 110 ... ECU, 116, 118 ... Hydraulic actuator, 120 ... Steering shaft, 122 ... Resolver, 124 ... Gear box, 126 ... Tie rod, 150 ..., 200 ... Speed distribution part, 200a ... Torque distribution , 202, 202a ... torque command value generation unit, 204 ... subtractor, 206 ... PI control unit, 208 ... torque limit unit, 210 ... inverter, 220 ... speed sensor, 222 ... turning angle sensor, M1 ... travel motor, M1L ... Left travel motor, M1R ... Right travel motor, M2 ... Load handling motor, M3 ... Steering motor 300 ... motor drive device 700 ... control panel 610L ... left drive wheel 610R ... right drive wheel 702 ... ignition switch 704 ... steering wheel 706 ... lift lever 708 ... accelerator pedal 710 ... brake pedal 712: Forward / reverse lever, 714: Dashboard.

Claims (9)

A motor drive device that is mounted on an electric forklift and controls a left traveling motor and a right traveling motor that transmit power to each of the left driving wheel and the right driving wheel of the electric forklift based on a speed command value indicating a target speed of the electric forklift Because
A left speed command value for instructing the speed of the left travel motor and a right speed for instructing the speed of the right travel motor based on an input speed command value according to a driver's operation and a turning angle of the steered wheels of the electric forklift A speed distribution unit for calculating a command value;
According to an error between the left speed command value and the current speed of the left travel motor, a left torque command value indicating the torque of the left travel motor is generated, and the right speed command value and the current current of the right travel motor are generated. A torque command value generation unit that generates a right torque command value that indicates the torque of the right traveling motor according to the speed error of
With
When the turning angle is included in a dead zone provided corresponding to a range in which the rotation center of the electric forklift overlaps the drive wheel, at least one of a speed command value and a torque command value for the drive wheel on the inner ring side Is substantially zero, a motor drive device characterized by that.   2. The motor drive device according to claim 1, wherein when the turning angle is included in the dead zone, the speed distribution unit substantially sets a speed command value for the driving wheel on the inner ring side to zero. The speed distributor is
A function that defines the turning angle as an argument is defined,
A value obtained by setting the speed command value of the driving wheel on the outer wheel side to the input speed command value, turning the speed command value of the driving wheel on the inner wheel side, and multiplying the input speed command value by the value of the function when turning. Set to
The motor drive device according to claim 2, wherein the function is determined such that a value thereof is substantially zero when the turning angle is included in the dead zone. A torque limit unit that limits the left torque command value to an upper limit value or less according to the rotation speed of the left drive wheel, and limits the right torque command value to an upper limit value or less according to the rotation speed of the right drive wheel; Prepared,
4. The torque limit unit according to claim 1, wherein when the turning angle is included in the dead zone, the torque command value for the driving wheel on the inner ring side is substantially zero. 5. Motor drive device. A left traveling motor and a right traveling motor that are mounted on the electric forklift and that transmit power to the left driving wheel and the right driving wheel of the electric forklift are controlled based on a torque command value indicating a target torque of the driving wheel of the electric forklift. A motor drive device,
A left torque control value that indicates the torque of the left traveling motor and a right torque that indicates the torque of the right traveling motor based on the input torque control value according to the operation of the driver and the turning angle of the steered wheels of the electric forklift A torque distribution unit for calculating a control value;
According to an error between the left torque control value and the current torque of the left traveling motor, a left torque command value that indicates the torque of the left traveling motor is generated, and the right torque control value and the current current of the right traveling motor are generated. A torque command value generating unit that generates a right torque command value that indicates the torque of the right traveling motor according to the torque error of
With
When the turning angle is included in a dead zone provided corresponding to a range in which the rotation center of the electric forklift overlaps the drive wheel, at least one of a speed command value and a torque command value for the drive wheel on the inner ring side Is substantially zero, a motor drive device characterized by that.   6. The motor drive device according to claim 5, wherein when the turning angle is included in the dead zone, the torque distribution unit substantially sets a torque control value for the driving wheel on the inner ring side to zero. The torque distributor is
A function that defines the turning angle as an argument is defined,
A value obtained by setting the torque control value of the driving wheel on the outer ring side to the input torque control value and turning the torque control value of the inner wheel side driving wheel by multiplying the input torque control value by the value of the function during turning. Set to
The motor driving apparatus according to claim 6, wherein the function is determined such that a value thereof is substantially zero when the turning angle is included in the dead zone. A torque limit unit that limits the left torque command value to an upper limit value or less according to the rotation speed of the left drive wheel, and limits the right torque command value to an upper limit value or less according to the rotation speed of the right drive wheel; Prepared,
8. The torque limit unit according to claim 5, wherein when the turning angle is included in the dead zone, a torque command value for the driving wheel on the inner ring side is substantially zero. Motor drive device. Left drive wheel and right drive wheel,
A left travel motor and a right travel motor that transmit power to each of the left drive wheel and the right drive wheel;
The motor drive device according to any one of claims 1 to 8, which drives the left travel motor and the right travel motor;
An electric forklift characterized by comprising:

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