JP6575417B2 - Control device for vehicle running motor - Google Patents

Description

  The present invention relates to a control device for a vehicular travel motor.

  A technique for regenerative braking using a DC shunt motor as a traveling motor in a vehicle such as a battery forklift is known (for example, Patent Document 1).

Japanese Patent No. 3626893

  By the way, when the rotational speed of the motor decreases due to regenerative braking of the DC shunt motor, torque cannot be maintained by regenerative braking, so it is necessary to switch to plugging (reverse phase braking). At this time, if the rotational speed of the motor becomes smaller than the threshold value using the rotation sensor, the regenerative braking mode is switched to the plugging mode. However, even in a vehicle that does not have a rotation sensor, the regenerative braking mode is switched to the plugging mode. There is a need.

  An object of the present invention is to provide a control device for a vehicle travel motor that can switch a regenerative braking mode to a plugging mode for a travel motor without a rotation sensor.

According to the first aspect of the present invention, a DC shunt motor is used as the traveling motor, the armature energization switching element is configured as a circuit for energizing the armature of the DC shunt motor, and the field of the DC shunt motor is set. A control device for a vehicular travel motor having a bridge configuration of a field coil energization switching element as a circuit for energizing a coil, the controller for duty-controlling the armature energization switching element and the field coil energization switching element, Current detecting means for detecting a current flowing through the armature, and the control unit changes the current flowing through the armature by subtracting the previous armature current from the current armature current detected by the current detecting means. the amount over time calculated, the Control unit is configured to switch the regenerative braking mode and the plugging mode, sets the regenerative braking mode based on being switched back operation,
When the duty for energizing the armature is zero and the absolute value of the amount of change in the current flowing through the armature calculated in the regenerative braking mode is equal to or less than the threshold value, the control unit switches from the regenerative braking mode to the plugging mode. The gist is to have switching means for switching.

  According to the first aspect of the present invention, when the absolute value of the amount of change in the current flowing through the armature detected by the current detection means in the regenerative braking mode is less than or equal to the threshold value by the switching means, Switch to plugging mode. In this way, by grasping the amount of change in the current flowing through the armature as a detection element for the switching timing, it is possible to switch from the regenerative braking mode to the plugging mode for a traveling motor without a rotation sensor.

  As described in claim 2, in the vehicle travel motor control device according to claim 1, it may be mounted on a forklift.

  According to the present invention, it is possible to switch from the regenerative braking mode to the plugging mode for a traveling motor without a rotation sensor.

The schematic side view of a forklift. The circuit diagram of the control apparatus of the forklift travel motor. The flowchart for demonstrating an effect | action. (A), (b) is a time chart for demonstrating an effect | action. (A), (b) is a time chart for demonstrating an effect | action. The flowchart for demonstrating 2nd Embodiment. (A), (b), (c) is a time chart for demonstrating 2nd Embodiment. Time chart for comparison.

(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the forklift 10 is a battery forklift, and is a forklift that performs conveyance and cargo handling work with an electric motor. Drive wheels (front wheels) 12 a are provided at the front lower part of the vehicle body 11 of the forklift 10, and steering wheels (rear wheels) 12 b are provided at the rear lower part of the vehicle body 11. A cargo handling device 13 is provided at the front of the vehicle body 11.

  A mast 14 constituting the cargo handling device 13 is erected on the front portion of the vehicle body 11. The mast 14 includes a pair of left and right outer masts 14a supported so as to be tiltable back and forth with respect to the vehicle body 11, and an inner mast 14b that slides up and down. A lift cylinder 15 is disposed at the rear of each outer mast 14a. A lift bracket 17 having a fork 16 is supported inside the inner mast 14b so as to be movable up and down. Then, the fork 16 is lifted and lowered together with the lift bracket 17 by the expansion and contraction operation of the lift cylinder 15.

  The pair of left and right tilt cylinders 18 is pivotally connected to the vehicle body (body frame) 11 at the base end side, and is rotatably connected to the side surface of the outer mast 14a. The mast 14 tilts back and forth as the tilt cylinder 18 is driven to expand and contract.

  The driver's cab 19 is provided with a driving seat 20 on which a driver can sit. A steering wheel column 21 is provided in front of the driving seat 20, and a steering wheel 22 for changing the steering angle of the steering wheel 12b is mounted on the steering wheel column 21. A lift lever 23 and a tilt lever 24 are provided on the front side of the cab 19. The lift lever 23 is a lever for moving the fork 16 up and down, and the tilt lever 24 is a lever for tilting the mast 14 in the front-rear direction. An accelerator pedal 25 is provided on the floor of the driver's seat, and the vehicle speed is set according to the amount of operation of the accelerator pedal 25 (accelerator opening).

  In addition, a direction lever (forward / reverse lever) 26 is provided on a side surface of the handle column 21, and the direction lever 26 is for instructing a traveling direction (traveling direction) of the vehicle.

  A battery 27, a travel motor (travel electric motor) 28, and a cargo handling motor (load handling electric motor) 29 are mounted on the vehicle body 11. A DC shunt motor is used as the traveling motor 28. The travel motor 28 is driven by the battery 27, and the drive wheel 12a is driven. Specifically, the output shaft of the travel motor 28 is connected to the rotation shaft of the drive wheel 12a via a speed reducer. When the output shaft is rotated by the drive of the travel motor 28, the rotation shaft of the drive wheel 12a is rotated along with the rotation. The drive wheel 12a is driven by rotation.

  In addition, a cargo handling motor 29 is driven by the battery 27, and a hydraulic pump (not shown) is driven by driving the cargo handling motor 29. Based on the driving of the hydraulic pump, the lift cylinder 15 and the tilt cylinder 18 are expanded and contracted so that the fork 16 can be moved up and down and tilted.

  As shown in FIG. 2, the control device 30 for the travel motor 28 is mounted on the forklift 10. A traveling motor 28 which is a direct current dividing motor has an armature (armature) 32 and a field coil (field coil) 33. The armature 32 is provided on the rotor, and the field coil 33 is provided on the stator.

  The control device 30 has a bridge circuit 31. The bridge circuit 31 has six switching elements Q1 to Q6. The armature energization switching elements Q5 and Q6 are configured as a bridge as a circuit for energizing the armature 32 of the travel motor (DC shunt motor). A field coil energizing switching element Q1, Q2, Q3, Q4 is used as a circuit for energizing the field coil 33 of the travel motor (DC shunt motor).

  Specifically, the positive electrode bus Lp is connected to the positive electrode of the battery 27 as a DC power source, and the negative electrode bus Ln is connected to the negative electrode of the battery 27. Switching elements Q1, Q2 are connected in series between positive electrode bus Lp and negative electrode bus Ln. Switching elements Q3 and Q4 are connected in series between positive electrode bus Lp and negative electrode bus Ln. A field coil 33 (stator coil) is connected between a midpoint between the switching elements Q1 and Q2 and a midpoint between the switching elements Q3 and Q4.

  Switching elements Q5 and Q6 are connected in series between positive electrode bus Lp and negative electrode bus Ln. An armature 32 (rotor coil) is connected between the midpoint between the switching elements Q5 and Q6 and the negative electrode bus Ln (ground). That is, the armature 32 is connected in parallel to the switching element Q6.

  Power MOSFETs are used for the switching elements Q1 to Q6. An IGBT (insulated gate bipolar transistor) may be used as the switching element. Feedback diodes D1 to D6 are connected in reverse parallel to the switching elements Q1 to Q6, respectively.

  The control device 30 includes current sensors 34 and 35 as current detection means. A current sensor 34 is provided in series with the armature 32, and a current (armature current) Ia flowing through the armature 32 is detected by the current sensor 34. A current sensor 35 is provided in series with the field coil 33, and the current (field current) If flowing through the field coil 33 is detected by the current sensor 35.

A main circuit contactor 36 is provided on the battery 27 side of the positive electrode bus Lp.
The control device 30 includes a controller 37. The controller 37 includes a microcomputer, a memory, and the like, and the memory stores various control programs necessary for driving the traveling motor 28 and various data and maps necessary for the execution. The control program includes a control program for rotationally driving the traveling motor 28, and can execute regenerative braking and plugging.

  In FIG. 2, the controller 37 is connected to the gates of the switching elements Q1 to Q6. The controller 37 as a control unit performs duty control on the armature energization switching elements Q5 and Q6 and the field coil energization switching elements Q1, Q2, Q3 and Q4.

  Current sensors 34 and 35 are connected to the controller 37. And the controller 37 outputs the duty signal which controls the traveling motor 28 so that it may become a target output to each switching element Q1-Q6 based on the detection signal of each sensor 34,35.

  The controller 37 inputs an operation signal output from the operation sensor in accordance with an operation by an occupant (operator) and controls the vehicle operation. More specifically, a direction switch 38 and an accelerator sensor 39 are electrically connected to the controller 37. The direction switch 38 is disposed in the handle column 21 and detects the operation position (forward position or reverse position) of the direction lever 26. The direction switch 38 outputs a detection signal corresponding to the operation position of the direction lever 26 to the controller 37. Then, the controller 37 detects that the operation position of the direction lever 26 is the forward movement position or the reverse movement position by inputting a detection signal from the direction switch 38.

  The accelerator sensor 39 detects the operation amount of the accelerator pedal 25. The controller 37 detects the presence / absence of the operation of the accelerator pedal 25 and the operation amount (accelerator opening) by inputting a signal from the accelerator sensor 39. Torque is determined according to the accelerator opening, and the regenerative torque is determined according to the accelerator opening by controlling the regenerative current of the armature 32. That is, when the accelerator pedal 25 is depressed, a large amount of armature current flows, and the duty is determined to control this current.

The controller 37 detects various operations and controls the traveling motor 28 to adjust the vehicle speed so that the rotational speed of the traveling motor 28 corresponds to the operation amount of the accelerator pedal 25.
The controller 37 detects a current (armature current) Ia flowing through the armature 32 and a current (field current) If flowing through the field coil 33 by signals from the current sensors 34 and 35. The controller 37 is configured to be switchable from the regenerative braking mode to the plugging mode. In the forklift 10, the traveling motor 28 is not provided with a rotation sensor.

Next, the operation of the control device 30 for the travel motor 28 of the forklift 10 will be described.
The controller 37 sets the regenerative braking mode when the direction lever 26 is switched back (operated from forward to reverse, or operated from reverse to forward) and the accelerator pedal 25 is depressed, and then the regenerative braking is performed. Transition from mode to plugging mode (reverse phase braking mode). In the following description, it is assumed that the vehicle is switched from forward to reverse. The controller 37 executes the process shown in FIG. 3 to switch from the regenerative braking mode to the plugging mode.

  As shown in FIG. 3, the controller 37 determines whether or not the traveling direction (traveling direction) of the vehicle is changed by the operation of the direction lever 26 in step S100. When the traveling direction (traveling direction) of the vehicle changes, the controller 37 proceeds to step S101 and sets the regenerative braking mode. In the regenerative braking mode, the controller 37 controls the duty of the switching elements Q1, Q4, and Q5 in FIG. 2, for example, and energizes the field coil 33 and the armature 32 through a current path indicated by a broken line in FIG.

  That is, the back coil electromotive force generated in the armature 32 energizes the field coil 33 through the path of the armature 32 → switching element Q5 → switching element Q1 → field coil 33 → switching element Q4 → armature 32. Further, a current due to the counter electromotive force generated in the armature 32 is passed through the path of the armature 32 → the switching element Q5 → the battery 27 → the armature 32, and the counter electromotive force generated in the armature 32 is returned to the battery 27.

  In step S102 in FIG. 3, the controller 37 determines the duty of the switching element Q5 (Q6), that is, the armature duty so that the actual armature current Ia becomes the target armature current Ia according to the accelerator opening. The controller 37 determines whether or not the armature duty is zero in step S103. If the armature duty is not zero, no processing is performed in step S105 (no operation), and if the armature duty is zero in step S103 (FIG. 4). (Timing of t1 in (a) and timing of t11 in FIG. 5A), the process proceeds to step S104. In step S104, the controller 37 adjusts the duty of the switching element Q5 (Q6) so as to adjust the field current If and the armature current Ia to make the actual armature current and the target armature current equal.

  The controller 37 subtracts the previous armature current Ia (n-1) from the change amount of the current (armature current) Ia flowing through the armature 32 detected by the current sensor 34 in step S106 (armature current Ia (n)). ) Is less than or equal to the first threshold value X1. If the absolute value of the change amount of the armature current Ia is not less than or equal to the first threshold value X1, the controller 37 proceeds to step S108 and determines whether or not the absolute value of the current armature current Ia (n) is less than or equal to the second threshold value X2. judge. If the absolute value of the change amount of the armature current Ia is larger than the first threshold value X1 and the absolute value of the armature current Ia is larger than the second threshold value X2, the controller 37 continues the regenerative braking mode in step S109.

  On the other hand, if the absolute value of the change amount of the armature current Ia is equal to or smaller than the first threshold value X1, or the absolute value of the armature current Ia is equal to or smaller than the second threshold value X2, the controller 37 proceeds to step S107 and sets the plugging mode. To do.

  In the plugging mode, the controller 37 controls the duty of the switching elements Q2, Q3, and Q5 in FIG. 2, for example, and secures the energization path for the field coil 33 and the armature 32 through the current path indicated by the alternate long and short dash line in FIG.

  That is, the field coil 33 is energized through the path of the positive electrode of the battery 27 → the switching element Q 3 → the field coil 33 → the switching element Q 2 → the negative electrode of the battery 27. Further, a current flows through the armature 32 through a path of the positive electrode of the battery 27 → the switching element Q 5 → the armature 32 → the negative electrode of the battery 27.

The behavior of the armature current Ia and the field current If during general deceleration will be described with reference to FIGS.
4A and 5A show the current (field current) If flowing through the field coil 33, the current flowing through the armature 32 (armature current) Ia, and the armature energization duty when the vehicle is decelerated. FIG. 4B and FIG. 5B show the amount of change in the current (armature current) Ia flowing through the armature 32. 4A and 4B show behavior on a flat road, and FIGS. 5A and 5B show behavior on a slope.

  4A and 5A, the horizontal axis represents time, the vertical axis represents current (field current) If flowing through the field coil 33, current (armature current) Ia flowing through the armature 32, and armature energization duty. I'm taking it. The controller 37 sets the armature energization duty according to the accelerator opening so that the armature current Ia according to the accelerator opening flows. In FIG. 4B and FIG. 5B, time is taken on the horizontal axis, and the amount of change in the armature current Ia is taken on the vertical axis.

  Regarding the control of the DC shunt motor, when the switchback operation is performed on a slope, the external force (force according to the road surface inclination, load, etc.) exceeds the regenerative braking force at the time of stop, so the machine base does not stop and slows down. The phenomenon of sliding down occurs. Therefore, it is necessary to switch from regenerative braking to plugging, but since the behavior of the armature current Ia and the field current If is different between the flat road and the slope road, it is difficult to unify the feeling between the flat road and the slope road. . In other words, when the feeling is adjusted on a flat road, a phenomenon in which switching (transition) from regenerative braking to plugging occurs on a slope.

  Regarding the amount of change in the duty for energizing the armature during regenerative braking by the forklift 10, on a flat road, the armature current Ia when the machine base stops during the period T1 in FIG. , 0A. Therefore, as shown in FIG. 4B, the change amount of the armature current Ia becomes a large value to some extent. The armature current Ia and the field current If are branched at the timing t1 in FIG. 4, and the forklift 10 is decelerating. By increasing the field current If so that the regenerative torque becomes the target value, the forklift 10 Stops.

  On the other hand, on the slope, the armature current Ia and the field current If branch at the timing of t11 in FIG. 5, and the period T10 until the armature current Ia becomes zero becomes longer. In particular, when the slope of the slope increases, the external force also increases, so that the braking force (regenerative force) and the external force are balanced. Or, external force will exceed. Therefore, it is not possible to shift from regenerative braking to plugging. There is a possibility that the armature current Ia does not become zero but slips down the slope at a slow speed due to the induced electric power generated by the external force acting on the machine base and the tire turning during the period T10 in FIG. That is, as shown in FIG. 4B, the amount of change in the armature current Ia is smaller than that on a flat road. Therefore, when the determination of switching (transition) from regenerative braking to plugging is defined only by the fixed threshold value of current, the balance between the machine base and the external force cannot be taken into account, leading to erroneous determination of switching (transition).

  Therefore, since the induced voltage generated in the motor 28 by the processing of steps S106 and S108 in FIG. 3 is proportional to the rotation speed, it is determined that the change amount of the armature current Ia is small, that is, it is not decelerating, and the regenerative braking is started. Switch to and make a transition.

  FIG. 8 is a comparative example, and shows the behavior of the field current If and the armature current Ia when regenerative braking is continued until the machine base stops. When the field current If is increased in order to maintain the braking torque during regenerative braking accompanying the switchback operation, the field current If increases infinitely as the vehicle speed approaches zero, so that it moves with inertial force when the forklift stops. It is necessary to switch from regenerative braking to plugging.

  On the other hand, in this embodiment, it is determined in step S106 in FIG. 3 that the absolute value of the change amount of the armature current Ia is equal to or less than the threshold value X1, or in step S108, the absolute value of the armature current Ia is determined to be the threshold value X2. By determining that the following has occurred, it is possible to detect the timing of transition from regenerative braking to plugging.

  In addition, since the rotational speed of the motor cannot be detected because the rotation sensor is not mounted, if the method of switching to plugging is adopted when the absolute value of the armature current Ia becomes smaller than the threshold value, the flat road of FIG. The torque is a value obtained by multiplying the armature current Ta × the field current If and the coefficient K, but does not reach the threshold value because the armature current Ia does not decrease. In the present embodiment, switching is performed when the absolute value of the change amount of the armature current Ia becomes smaller than the threshold value.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the control device for the vehicle travel motor, the controller 37 as a control unit is configured to be switchable from the regenerative braking mode to the plugging mode. When the absolute value of the amount of change in the current flowing through the armature 32 detected by the current sensor 34 as the current detection means in the regenerative braking mode is equal to or less than the threshold value, the controller 37 switches from the regenerative braking mode to the plugging mode. Means (switching function). Therefore, by grasping the amount of change in the current flowing through the armature 32 as a detection element for the switching timing, it is possible to switch from the regenerative braking mode to the plugging mode for a traveling motor without a rotation sensor. In particular, the regenerative braking mode can be switched to the plugging mode even in a situation where an external force such as a slope is applied.

(2) Since it is mounted on a forklift, it is practical.
(Second Embodiment)
Next, the second embodiment will be described focusing on the differences from the first embodiment.

  In 2nd Embodiment, it is set as the structure shown in FIG. 6 instead of FIG. Compared to FIG. 3, in FIG. 6, the process of step S200, the process of step S201, and the process of step S202 are added.

  The controller 37 is configured to be able to switch from the regenerative braking mode to the plugging mode. In the regenerative braking mode, the duty of the armature energizing switching elements Q5 and Q6 is zero and the current flowing through the armature 32 (armature current) in step S200 of FIG. ) When the absolute value of Ia becomes equal to or less than the threshold value X3, the current regenerative braking mode is switched to the plugging mode. When switching from the regenerative braking mode to the plugging mode, if the duty of the armature energizing switching elements Q5 and Q6 becomes zero in step S201 of FIG. 6 before switching, the current (field current) If flowing through the field coil 33 After switching, the duty control is performed so that the current If flowing in the field coil 33 in step S202 has the same value and the opposite direction to the current If flowing in the field coil 33 before switching.

  As described above, in the present embodiment, since the induced voltage generated by the motor is proportional to the rotation speed, the duty for armature energization (armature PWM output duty) also depends on the rotation speed for the detection of the switching timing. When the induced voltage decreases, the armature current Ia flowing through the motor also decreases. Therefore, the switching detection condition is that the armature energization duty = 0 and the absolute value of the armature current Ia is equal to or less than the threshold value X3.

  Further, for torque fluctuation suppression before and after switching, since the motor-generated torque is proportional to the multiplication value of the field current If and the armature current Ia, when the duty for energizing the armature becomes 0 in step S201 before switching, The torque fluctuation is suppressed while increasing the current If and maintaining the regenerative braking force. In step S202 after switching, the field current If (after switching) is multiplied by (-1) times the field current If before switching.

  As a behavior at the time of the transition from the regenerative braking to the plugging on the downhill road in the forklift 10 due to the switchback operation, as shown in FIG. Since the torque cannot be maintained as shown in (b), switching to plugging is performed. At that time, since the induced voltage generated from the motor is proportional to the rotation speed, the armature current Ia flowing to the motor also decreases when the induced voltage decreases by utilizing the fact that the duty for energizing the armature also depends on the rotation speed. Switching is performed at timing t22 when the torque gently decreases.

  Before switching, the field current If is increased at the timing t21 when the armature energization duty becomes 0 (step S201). Since the motor torque is proportional to the field current If × the armature current Ia, the torque is held by an increase in the field current If. After the switching, the torque fluctuation is suppressed by setting the field current If after switching to (−1) × the field current If before switching (step S202).

In this way, it is possible to switch from regenerative braking to plugging without a rotation sensor. Further, it is possible to switch from regenerative braking to plugging while maintaining the torque.
According to the above embodiment, the following effects can be obtained.

  (3) In the regenerative braking mode, the controller 37 has the duty of the armature energization switching elements Q5, Q6 being zero, and the absolute value of the current (armature current) Ia flowing through the armature 32 detected by the current sensor 34 as current detection means When the value becomes equal to or less than the threshold value X3, there is switching means (switching function) for switching from the regenerative braking mode up to that point to the plugging mode. Therefore, the regenerative braking mode can be switched to the plugging mode for the traveling motor 28 without the rotation sensor.

  (4) The controller 37 as switching means further has torque control means (torque control function). When switching from the regenerative braking mode to the plugging mode, the torque control function increases the current passed through the field coil 33 when the duty of the armature energizing switching elements Q5 and Q6 becomes zero before switching, and after switching, Duty control is performed so that the current flowing through the field coil 33 is the same value and opposite to the current flowing through the field coil 33 before switching. Therefore, when the traveling motor 28 without the rotation sensor is switched from the regenerative braking mode to the plugging mode, torque fluctuation before and after the switching can be suppressed.

The embodiment is not limited to the above, and may be embodied as follows, for example.
-Although applied to a forklift, it is not limited to this. For example, an industrial vehicle other than a forklift may be used, or a vehicle other than an industrial vehicle may be used.

  DESCRIPTION OF SYMBOLS 10 ... Forklift, 28 ... Traveling motor, 30 ... Control apparatus, 34 ... Current sensor, 37 ... Controller, Q1, Q2, Q3, Q4 ... Field coil energization switching element, Q5, Q6 ... Armature energization switching element.

Claims (2)

A DC shunt motor is used as a travel motor, and a bridge configuration of an armature energizing switching element is provided as a circuit for energizing the armature of the DC shunt motor, and field coil energization is provided as a circuit for energizing a field coil of the DC shunt motor. A vehicle travel motor control device having a bridge configuration of a switching element for a vehicle,
A control unit for duty-controlling the armature energization switching element and the field coil energization switching element;
Current detecting means for detecting a current flowing through the armature;
With
The control unit calculates the change amount of the current flowing through the armature over time by subtracting the previous armature current from the current armature current detected by the current detection unit,
The control unit is configured to be able to switch between a regenerative braking mode and a plugging mode, and sets the regenerative braking mode based on a switchback operation.
When the duty for energizing the armature is zero and the absolute value of the amount of change in the current flowing through the armature calculated in the regenerative braking mode is equal to or less than the threshold value, the control unit switches from the regenerative braking mode to the plugging mode. A control device for a vehicular travel motor comprising switching means for switching.   The vehicle travel motor control device according to claim 1, wherein the vehicle travel motor control device is mounted on a forklift.

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