JP2000125419A - Control method for dc shunt motor and control device for forward and reverse drive of industrial vehicle using the control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for a DC shunt motor and a control device, for an industrial vehicle such as a battery forklift or the like, which prevents torque from becoming dull, especially when the rotating direction of the DC shunt motor is converted and when the forward and reverse drive of the industrial vehicle is changed over. SOLUTION: Regarding this control method for a DC shunt motor and this control device for an industrial vehicle, when the forward and reverse drive of the industrial vehicle is changed over and controlled, a transistor drive circuit 18 (or a chopper control circuit 20) is controlled. Then, the duty ratio of a transistor Q8 for regeneration is controlled to a ratio which is smaller than 100%. An exciting current is changed over at a prescribed timing. Then the duty ratio of the transistor Q8 for regeneration is set maximum, and the exciting current is changed over in a state in which a large armature current is flowing. A reverse drive is performed, and the torque does not become dull.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a DC shunt motor and a forward / reverse control device for an industrial vehicle using the control method.

[0002]

2. Description of the Related Art Today, industrial vehicles such as battery forklifts replace mechanical mechanisms with electrical circuits and mechanically complicated controls with electrical controls. For example,
Switching of the running direction of the vehicle, power steering control, and the like control the rotation of the DC motor by performing chopper control of the transistor circuit, thereby achieving the desired control.

[0003] For example, FIG. 3 is a circuit diagram of a motor drive circuit in an industrial vehicle. In FIG. 1, reference numeral 1 denotes a battery, which supplies a predetermined voltage to the motor drive circuit 2.
The motor drive circuit 2 includes a DC motor 3, a running transistor Q1, a regenerating transistor Q2, a transistor drive circuit 4, a current sensor 5, and a rotation sensor 6. The above-described DC motor 3 is a shunt motor, and is driven by excitation from an excitation circuit 7. The excitation circuit 7 includes an excitation coil 8, transistors Q3 to Q6, a transistor drive circuit 9, and a current sensor 10.

The above-described transistor drive circuits 4 and 9 are controlled by a control signal output from a chopper control circuit 11, and a forward / reverse switching signal 12 is supplied to the chopper control circuit 11.

[0005] The rotational force of the DC motor 3 is used, for example, for traveling of an industrial vehicle, and the traveling direction is switched by switching the direction of the current flowing through the exciting coil 7. For example,
When the DC motor 3 is driven by driving the transistors Q3 and Q6 and supplying a current in the direction of the solid line to the exciting coil 7, the transistor drive circuit 9 drives the transistors Q3 and Q6 by supplying the forward / reverse switching signal 12. The driving direction of the DC motor 3 is changed by switching the driving of the transistors Q4 and Q5 and changing the direction of the exciting current.

FIG. 4 is a time chart for explaining the control at the time of the forward / reverse switching. Note that the time chart shown in the figure shows the circuit operation after the forward / reverse switching signal 12 has already been supplied.

First, the driving transistor Q1 is in the ON state, and in the above-described excitation state, the DC motor 3 is driven, and the vehicle is traveling forward or backward. When the forward / reverse switching signal 12 is switched in this state, the chopper control circuit 11
Detects this and sends a control signal to the transistor drive circuit 4 to turn off the traveling transistor Q1. And
The regenerative control is performed by repeatedly turning on / off the regenerating transistor Q2. By this processing, the armature current (Ia) of the DC motor 3 gradually decreases as shown in FIG. 4B, and during this time, the on / off duty of the regeneration transistor Q2 as shown in FIG. Increases.

Thereafter, the current sensor 5 detects the armature current (I
When it is detected that a) has decreased to a constant value d, for example, driving of the transistors Q3 and Q6 is performed at timing A shown in FIG. Switch. By this control, the exciting current (If) flowing through the exciting coil 8 gradually changes from the forward direction to the reverse direction as shown in FIG. 3A, and is switched to the powering process at the timing of FIG.

[0009]

In the above-mentioned conventional control,
In the latter half of the regeneration period, the speed of the DC motor 3 decreases,
The duty of the regenerating transistor Q2 becomes 100%, and the armature current gradually decreases as shown in FIG. 4B. Therefore, the forward / backward switching process is performed during this time, but as shown in the figure, the armature current during this time (between AB) is low, and so-called torque loss occurs. In particular, when the operator operates, for example, a lever for forward / reverse switching, the driver feels a torque loss.

SUMMARY OF THE INVENTION The present invention provides a method of controlling a DC shunt motor for smooth switching between forward and backward movement by eliminating torque loss when switching between forward and backward movement of an industrial vehicle, and forward and backward movement of an industrial vehicle using the control method. A control device is provided.

[0011]

According to the first aspect of the present invention, there is provided a regenerative process for regenerating a DC shunt motor with a duty ratio smaller than a maximum duty ratio at the time of a rotation direction switching process. When the armature current of the DC shunt motor reaches a predetermined value, an exciting current control process that switches the direction of the exciting current, and a control process that controls the duty ratio of the regenerative process simultaneously with the exciting current control process,
Achieved by providing a control method of a DC shunt motor that performs a rotation direction switching process for switching the rotation direction of the DC shunt motor in a torque state based on the armature current increased by the maximum control of the duty ratio. it can.

Here, the regenerative processing has a configuration in which the regenerative processing of the DC shunt motor is performed at a duty ratio smaller than the maximum duty ratio. For example, a duty ratio of 90% or 80% with respect to a maximum duty ratio of 100%. Performs regenerative processing. By this process, the armature current is gradually reduced.For example, when a predetermined armature current value before torque loss is reached, the duty ratio of the regeneration process is maximized by the control process, and the excitation current control process is performed. Switch the excitation current.

[0013] With this configuration, the armature current is increased, the rotation direction can be switched in a state where the torque is large, and the loss of torque can be prevented.
A smooth rotation direction switching process can be performed.

[0014] The above object is achieved according to the second aspect of the present invention.
In the switching process of the rotation direction, the regenerative means for regenerating the DC shunt motor at a duty ratio smaller than the maximum duty ratio, and when the armature current of the DC shunt motor reaches a predetermined value, the direction of the exciting current is switched. Exciting current control means, control means for controlling the duty ratio of the regenerative processing at the same time as the control of the exciting current control means, and the DC current in the torque state based on the armature current increased by the maximum control of the duty ratio. This can be achieved by providing a control device for a DC shunt motor having a rotation direction switching means for switching the rotation direction of the shunt motor.

According to the present invention, the invention of the control method for a DC shunt motor according to the first aspect is realized by a control device. With such a configuration, the electric motor can be switched when the rotation direction is switched. The direction switching can be performed in a state where the slave current is increased and the torque is large, torque loss can be prevented, and a smooth rotation direction can be switched.

According to the third aspect of the present invention, the above object is provided.
In the switching process of the rotation direction, the regenerative means for regenerating the DC shunt motor at a duty ratio smaller than the maximum duty ratio, and when the armature current of the DC shunt motor reaches a predetermined value, the direction of the exciting current is switched. Exciting current control means, control means for controlling the duty ratio of the regenerative processing at the same time as the control of the exciting current control means, and the DC current in the torque state based on the armature current increased by the maximum control of the duty ratio. By providing a forward / reverse control device for an industrial vehicle having a rotational direction switching means for switching the rotational direction of the shunt motor and a conversion mechanism for converting the rotational direction switching into forward / reverse switching of the industrial vehicle. Can be achieved.

The present invention is directed to an apparatus for controlling the forward / reverse movement of an industrial vehicle using the above-described method of controlling a DC shunt motor. With this configuration, the armature current is increased at the time of forward / reverse switching. The forward / backward switching process can be performed in a state where the torque is large, torque loss can be prevented, and a smooth forward / backward switching process can be performed in an industrial vehicle.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram of a control device for explaining an example of a battery forklift as a control device for an industrial vehicle of the embodiment. FIG. 1 is also a circuit diagram of a control device of the DC shunt motor.

In FIG. 1, a battery 14 is mounted on a battery forklift (not shown), and supplies an output of a predetermined voltage (for example, 24 V) from the battery 14 to a motor drive circuit 15. The motor drive circuit 15 includes a DC motor 16, a running transistor Q7, a regenerating transistor Q8, a current sensor 17, a transistor drive circuit 18, and a rotation sensor 19.

The driving transistor Q7 supplies an armature current (Ia) to the DC motor 16, and
, And is turned on / off by a signal output from the transistor drive circuit 18. The regenerating transistor Q8 is a switch for performing regenerative control when switching the rotation direction of the DC motor 16, and is turned on / off in accordance with a control signal output from the transistor drive circuit 18 as described above.

The current sensor 17 is a sensor for detecting the value of the armature current (Ia) supplied to the DC motor 16. A rotation sensor 19 provided near the DC motor 16 is an encoder for knowing the rotation direction of the DC motor 16 and the like.

The chopper control circuit 20 sends a control signal to the above-described transistor drive circuit 18 to control the driving of the transistors Q7 and Q8.
And a detection signal is input from the current sensor 17 and the rotation sensor 19 described above.

On the other hand, the supply of the exciting current (If) to the DC motor 16 is performed by the exciting circuit 21. That is, the excitation circuit 21 includes an excitation coil 22, four transistors Q9 to Q12 formed in a bridge shape, a current sensor 23, and a transistor drive circuit 24. The excitation coil 22 follows the drive control of the transistors Q9 to Q12. Supplied with the exciting current (If).

The transistors Q9 to Q12 are controlled by a control signal output from the transistor drive circuit 24. For example, when a current flows in the direction of a solid arrow of the exciting coil 22, the transistor drive circuit 24 controls the transistors Q9 and Q12. Outputs a control signal to the gate,
The transistors Q9 and Q12 are turned on, and the above current flows to the exciting coil 15. When a current flows through the exciting coil 22 in the direction of the dotted arrow, the transistors Q10 and Q1
A control signal is output to the gate of the transistor 1 to drive the transistors Q10 and Q11, and the current flows to the exciting coil 22.

The above-described transistor drive circuit 24
Is also output from the above-described chopper control circuit 20, and the detection signal of the current sensor 23 is also supplied to the chopper control circuit 20. Further, a forward / reverse switching signal 25 output in conjunction with a lever operation (not shown) is input to the chopper control circuit 20.

The driving transistor Q7, the regenerating transistor Q8, and the four exciting transistors Q9 to Q12 are connected in parallel with the diodes D7 to D12, respectively.
D12 is connected and is used for bypass when a reverse current flows through the corresponding transistor.

The chopper control circuit 20 includes an R (not shown)
Control is performed according to a program stored in the OM, and control signals are output to the above-described running transistor Q7, regenerating transistor Q8, and transistors Q9 to Q12 at a predetermined timing.

In the above configuration, the processing operation of this embodiment will be described below. First, it is assumed that the DC motor 16 is driven, for example, in the forward direction by the control of the chopper control circuit 20. That is, under the control of the chopper control circuit 20, a control signal is output from the transistor drive circuit 18 to the transistor Q7, and a current flows through the armature winding of the DC motor 16, for example, by turning on the transistors Q9 and Q12, thereby turning on the excitation coil 22. , And the above-described driving is performed.

In this state, the operator operates a lever (not shown) and sends the forward / reverse switching signal 25 to the chopper control circuit 2.
When it is output to 0, the circuit operation according to the time chart shown in FIG. 2 is performed thereafter. This process is performed according to a control signal output from the chopper control circuit 20, and this control signal is based on a program stored in a ROM (not shown) as described above.

First, when the forward / reverse switching signal 25 is supplied, the chopper control circuit 20 outputs a control signal to the transistor drive circuit 18 to immediately stop the driving of the running transistor Q7, Q
7 is stopped.

Next, a regeneration process (regeneration period) shown in FIG.
Is started, and the transistor drive circuit 18 sends an on / off signal to the regeneration transistor Q8 with a duty less than 100% under the control of the chopper control circuit 20. That is, during this time, the exciting current continues to flow in the exciting coil 22 in the same direction, and the armature current (Ia) supplied to the DC motor 16 is gradually reduced. However, the duty is not set to 100% during this time.

Next, when the armature current reaches a certain value, the following processing is performed to switch the excitation direction of the DC motor 16. That is, the current value of the armature current (Ia) is detected by the above-described current sensor 17. For example, when the current value detected by the current sensor 17 reaches a predetermined value e, the transistor is controlled by an instruction from the chopper control circuit 20. By controlling the drive circuit 24, the transistors to be turned on are switched from Q9 and Q12 to Q10 and Q11. Here, the above-mentioned predetermined value e is a current value of a certain level or more, and when the current sensor 17 detects this predetermined value e, the direction of the exciting current (If) is switched.

At the same time as the above processing, the on / off duty of the control signal output from the transistor drive circuit 18 is set to 100%, and the armature current (I
a) increase. By this processing, the armature current (Ia) increases in the regeneration direction during the switching period as shown in FIG. 2B, and a large torque corresponding to the armature current (Ia) can be obtained. Therefore, even if the forward / reverse switching process is performed during this time, torque loss does not occur.

Next, when the exciting current in the power running direction increases and the current sensor 23 detects the value of the necessary exciting current (If), a detection signal is sent to the chopper control circuit 20, and thereafter, under the control of the chopper control circuit 20, Then, the driving of the regenerating transistor Q8 is stopped. And the driving transistor Q
7, the DC motor 16 is rotated in the reverse direction (powering period shown in FIG. 2). By this processing, when the vehicle changes direction from the above-mentioned forward movement to backward movement, it is possible to smoothly switch back and forth without causing torque loss.

In the above-described example, the vehicle is switched from forward to reverse. On the contrary, when the vehicle is switched from reverse to forward, the same processing can be performed to smoothly switch between forward and backward.

By performing control as described above, according to the present embodiment, when switching between forward and backward, there is no loss of torque, and a more smooth forward and backward switching process can be performed. According to the above-described embodiment, when the duty ratio is increased at the timing A shown in FIG. 2, there is a possibility that the DC motor 16 may be shocked. In such a case, the transistor drive circuit 18 is controlled to gradually increase the duty ratio of the regenerating transistor Q8, as shown by 'in FIG.
You may comprise so-called soft start.

Further, in the description of this embodiment, the duty ratio is described as being less than 100%, but the specific duty ratio differs depending on the type of industrial vehicle, for example, 90%, 8%.
Select an appropriate duty ratio such as 0%.

The industrial vehicle of the present embodiment is not limited to a battery forklift, and can be applied to forward and backward control of other industrial vehicles.

[0039]

As described above, according to the DC shunt motor control method and control apparatus of the present invention, it is possible to eliminate torque loss and perform smoother rotation direction conversion.

Further, according to the control device for an industrial vehicle of the present invention, it is possible to eliminate a torque loss and perform smoother forward / reverse switching control.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a circuit configuration of a control device for a DC shunt motor and a control device for an industrial vehicle according to an embodiment of the present invention.

FIG. 2 is a time chart illustrating a processing operation of the embodiment.

FIG. 3 is a diagram illustrating a circuit configuration of a conventional device.

FIG. 4 is a time chart for explaining a processing operation of a conventional example.

[Explanation of symbols]

 14 Battery 15 Motor drive circuit 16 DC motor 17 Current sensor 18 Transistor drive circuit 19 Rotation sensor 20 Chopper control circuit 21 Exciting circuit 22 Exciting coil 23 Current sensor 24 Transistor drive circuit 25 Forward / reverse switching signal Q7 to Q12 Transistor

Claims (3)

[Claims] In the switching process of the rotation direction, a regenerative process for regenerating a DC shunt motor with a duty ratio smaller than a maximum duty ratio; and when an armature current of the DC shunt motor reaches a predetermined value.
An exciting current control process for switching the direction of the exciting current; a control process for controlling the duty ratio of the regenerative process to the maximum simultaneously with the exciting current control process; and a torque state based on the armature current increased by the maximum control of the duty ratio. And a rotation direction switching process for switching a rotation direction of the DC shunt motor. 2. A regenerating means for regenerating a DC shunt motor with a duty ratio smaller than a maximum duty ratio during a switching process of a rotation direction, wherein the armature current of the DC shunt motor reaches a predetermined value.
Exciting current control means for switching the direction of the exciting current; control means for controlling the duty ratio of the regenerative processing at the same time as control of the exciting current control means; and armature current increased by the maximum control of the duty ratio. A control device for a DC shunt motor, comprising: rotation direction switching means for switching a rotation direction of the DC shunt motor in a torque state. 3. A regenerating means for regenerating a DC shunt motor with a duty ratio smaller than a maximum duty ratio during a switching process of a rotation direction, wherein: when the armature current of the DC shunt motor reaches a predetermined value,
Exciting current control means for switching the direction of the exciting current; control means for controlling the duty ratio of the regenerative processing at the same time as control of the exciting current control means; and armature current increased by the maximum control of the duty ratio. In a torque state, a rotation direction switching means for switching the rotation direction of the DC shunt motor, and a conversion mechanism for converting the rotation direction switching into forward and backward switching of the industrial vehicle, comprising: Vehicle forward / backward control device.