JPH10285714A - Device for controlling dc shunt motor for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a DC shunt motor controlling device of a simple structure without a rotation sensor, capable of achieving smooth and efficient control. SOLUTION: This device is provided with an armature voltage detecting means 11, current-detecting means 12, 13 of the armature and field system, an accelerator sensor 14, an armature-adjusting means capable of adjusting the size and direction of the voltage and current of the armature, a field current adjusting means 30 and a controlling means 40. The controlling means 40 adjusts the field current and the armature voltage to obtain a given revolutions in power running. When the accelerator is operated to return, regenerative control is performed with a constant braking torque Tb. In regenerative running, field current value Ifs is set, so that the armature voltage value Vd at the time of zero load torque in the power running can be made almost equal to the armature voltage value Vb at the time of a changeover from the regenerative to power running.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a DC motor driving an industrial vehicle.

[0002]

2. Description of the Related Art In an industrial vehicle driven by a DC motor using a battery as a power source, the motor is controlled at a target speed corresponding to an operation amount of an accelerator while maintaining good power efficiency during power running. At the time of braking, the energy of the electric motor is regenerated to the battery as much as possible, and the power consumption is controlled to be as small as possible.

That is, as shown in FIG. 8, during power running, the rotation speed of a motor 90 is detected by a rotation sensor 91, and an armature circuit driving transistor 921 and field circuit driving transistors 931 to 934 (a set of 931 and 933 or 93
2934) in a predetermined current direction (the regenerative transistor 922 is turned off), and the armature current Ia and the field current If are adjusted to achieve a target rotation speed corresponding to the accelerator operation amount a. I do. In the figure, reference numeral 991 denotes a battery, reference numeral 992 denotes an accelerator sensor for detecting an operation amount of an accelerator, reference numeral 901 denotes a field coil, reference numeral 94 denotes a chopper control device, reference numerals 925 and 935 denote transistor drive circuits, and reference numerals 912 and 913. Is a current sensor for armature current and field current.

When the brake is operated, when the direction switch is switched (switchback), when the accelerator pedal is released, and when the accelerator is returned (when the so-called accelerator-linked regeneration condition is satisfied), the armature circuit drive transistor is turned on. 921 is turned off, and the regeneration current of the motor 90 is
Regenerates to 91.

In particular, at the time of the accelerator-linked regeneration, the rotation speed of the electric motor 90 is detected by the rotation sensor 91, and the rotation speed is a value at zero load torque corresponding to the new operation amount of the accelerator while braking with a constant braking torque. Is detected, and the control mode is switched again to the powering drive control. The curve (function) indicating the relationship between the load torque and the rotation speed is uniquely determined by the operation amount of the accelerator (see FIG. 4A), and the value of the load torque is determined by the armature current and the field force. It can be calculated from the value of the current.

[0006]

However, in order to perform the regeneration in conjunction with the operation of the accelerator as described above, a rotation sensor 91 for detecting that the rotation speed of the electric motor 90 has reached a predetermined value is required. A buffer circuit, an integrator and the like are required for the control device 94 as an input circuit of the rotation sensor 91. Therefore, the configuration becomes complicated and the cost increases. The present invention has been made in view of such a conventional problem, and has a simple and inexpensive configuration that does not require a rotation sensor, and is capable of realizing smooth and efficient control. Is intended to be provided.

[0007]

The present invention provides a voltage detecting means for detecting an armature voltage of a DC shunt motor driving an industrial vehicle, a current detecting means for detecting an armature current and a field current of the DC motor, An accelerator sensor for detecting an operation amount of an accelerator or a neutral state of a direction switch; an armature adjusting means capable of switching a direction of an armature current and adjusting a magnitude of a voltage and a current of the armature; A magnetic current adjusting means for calculating a current load torque from the armature current value and the field current value, so that the armature has a predetermined rotational speed corresponding to the detection signal of the accelerator sensor and the load torque; Control means for controlling the electric motor to operate the adjustment means and the field current adjustment means, and the control means is provided when the accelerator is depressed during power running. In other words, the field current and the armature voltage are adjusted while restricting the armature current to a predetermined value or less so as to achieve a predetermined rotation speed corresponding to the load torque and the accelerator operation amount a1. When the operation amount is relatively returned from the operation amount a1 that is relatively large to the operation amount a2 that is small, the power of the DC motor is changed so as to shift to the relationship between the load torque and the rotation speed corresponding to the new accelerator operation amount a2. A predetermined constant braking torque Tb while regenerating
During the regenerative braking, the armature voltage value Vd with respect to the rotation speed Nd2 when the load torque is zero and the constant value in the relationship between the load torque and the rotation speed during power running corresponding to the new accelerator operation amount a2. The value of the field current Ifs is set in advance so that the value of the armature voltage Vb when the rotation speed Nd2 is obtained by braking with the braking torque Tb of FIG. While maintaining the Ifs constant, the armature current is controlled so that the armature current Ias corresponds to the constant braking torque Tb. When the armature voltage that decreases with the rotation speed reaches the Vb,
The control device for a DC shunt motor for an industrial vehicle is characterized in that the motor is controlled so as to return to the powering control corresponding to the accelerator operation amount a2.

The first point of particular interest in the present invention is that the current load torque is calculated from the value of the armature current and the value of the field current, and the field current is controlled to be constant. The motor speed is calculated from the voltage, and the armature voltage (motor) is controlled to a predetermined speed corresponding to the load torque and the accelerator operation amount. That is, the motor can be controlled to a state corresponding to the accelerator sensor (the number of rotations corresponding to the load) without using the speed sensor.

For example, at the time of power running, the field current and the armature voltage are adjusted, and control is performed so that a predetermined rotational speed corresponding to the load torque and the accelerator operation amount a1 is obtained. That is,
A target rotation speed is set from the current load torque based on a relational expression between the load torque and the rotation speed corresponding to the current accelerator operation amount. When the field current is set to a predetermined value, the relationship between the rotation speed and the armature voltage is uniquely determined as shown in FIG. 4 (b). The rotation speed can be known by the detection, and the armature adjusting means is operated so that the armature voltage corresponds to the target rotation speed.

Similarly, during the regenerative control, the braking torque is controlled to be constant, so that when the field current is set to be constant, the relationship between the rotational speed and the armature voltage is limited as shown in FIG. It is uniquely determined according to the magnetic current, and similarly, the armature voltage can be detected to determine the rotation speed. Then, the armature adjusting means is operated until the armature voltage at the target rotation speed corresponding to the new accelerator operation amount a2 is reached. As a result, according to the present invention, the rotation sensor is not required, and the voltage detecting means which is required instead can be configured cheaper and simpler than the rotation sensor, so that the device is simple and inexpensive.

A second point of particular interest in the present invention is to control the transition from the regenerative control to the powering control in the accelerator-linked regeneration as follows. That is, the armature voltage value Vd with respect to the rotation speed Nd2 when the load torque of the powering control characteristic corresponding to the new accelerator operation amount a2 becomes zero, and the armature voltage Vb at the rotation speed Nd2 in the regeneration control characteristic. The value Ifs of the field current is set in advance so that the value becomes substantially equal to the value, and the armature current Ias corresponding to the constant braking torque Tb is obtained while keeping the value of the field current constant. The armature current is controlled as described above, and when the armature voltage that decreases with the rotation speed reaches the above-described Vb, the process returns to powering control.

As a result, it is possible to smoothly shift from the regenerative control to the power running control even though the speed is not detected using the speed sensor. That is, when the transition from the regenerative control to the power running control is performed, the difference between the armature voltage Vb immediately before switching based on the regenerative control and the control target value Vd at the time of the transition to the power running control is small, so that the transition between the two control modes is extremely smooth. Becomes This is because the control deviation at the moment of transition of the armature voltage, which is the main operation amount during power running, is extremely small. In addition, useless transient control such as overshoot of the speed at the time of the above-mentioned switching does not occur.

[0013] The armature adjusting means may be, for example, a second switching element connected in parallel with the armature of the DC motor and operated during regeneration, and the armature and the second switching element. And a rectifying element arranged in series with the first and second switching elements and operated in the reverse polarity in parallel with the first and second switching elements. The control means controls the second switching element to be in an off state and the first switching element in chopper control during power running control, and sets the first switching element in an off state during regenerative control. The above control can be realized by chopper controlling the two switching elements (see FIGS. 2 and 3).

That is, as shown in FIG. 2, by turning off the second switching element and performing chopper control on the first switching element, electric power can be supplied from the power supply side to the electric motor to perform power running driving. Then, the motor operates according to the chopper control amount of the first switching element. On the other hand, as shown in FIG. 3, the first switching element is turned off, the second switching element is chopper-controlled, and the energy of the motor is transferred to the power supply side through a diode route inserted in parallel with the first switching element. Can be regenerated. Further, the regenerative amount power can be controlled by adjusting the chopper control amount of the second switching element.

On the other hand, the field current adjusting means is constituted by, for example, a bridge connection circuit of a switching element in which a field coil of a DC motor is connected to a bridge portion of an opposite bridge terminal. can do. The control means controls one of the two sets of the pair of switching elements on the sides facing each other in the bridge circuit by chopper control in accordance with the rotational direction and sets the other set to the off state. The magnitude and direction of the field current can be controlled (see FIGS. 2 and 3). That is, by selecting a pair of switching elements to be chopper-controlled, the polarity (direction) of the field current is determined, and the magnitude of the current can be changed by the chopper control amount.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment This embodiment is, as shown in FIG. 1, a voltage detecting means 11 for detecting an armature voltage Va of a DC shunt motor 81 for driving an industrial vehicle, an armature current Ia and a field current of the DC motor 81. Current detecting means 12 and 13 for detecting If, an accelerator sensor 14 for detecting an operation amount of an accelerator and a neutral state of a direction switch, a direction of an armature current Ia can be switched, and a voltage Va and a current Ia of an armature are provided. The armature adjusting means, which will be described in detail later, which can adjust the size of
0, the current load torque T is calculated from the value of the armature current and the value of the field current, and the armature adjusting means is adjusted to a predetermined rotational speed corresponding to the detection signal of the accelerator sensor 14 and the load torque. DC shunt motor 81 for industrial vehicles having a control means 40 for operating the field current adjusting means 30
Of the control device 1.

When the accelerator is depressed, the control means 40 sets the armature current Ia to a predetermined value or less so that the rotation speed becomes a predetermined rotation speed corresponding to the load torque T and the accelerator operation amount a1. The field current If and the armature voltage Va are adjusted while limiting. On the other hand, when the operation amount of the accelerator is returned from the operation amount a1 that is relatively large to the operation amount a2 that is small, the DC motor is shifted to the relationship between the load torque and the rotation speed corresponding to the new accelerator operation amount a2. While the electric power of 81 is regenerated to the power supply side 85, braking is performed with a predetermined constant braking torque Tb (FIG. 6).

At the time of the regenerative braking, the control means 40 determines the armature voltage Vd with respect to the rotational speed Nd2 when the load torque is zero in the relationship between the load torque and the rotational speed during power running corresponding to the new accelerator operation amount a2. And the value of the field current Ifs is set in advance so that the value of the armature voltage Vb when the value of the armature voltage Vb when the rotation speed Nd2 is obtained by braking with the constant braking torque Tb becomes substantially the same value. The armature current is controlled so that the armature current Ias corresponding to the constant braking torque Tb is maintained while maintaining the value of the field current at the constant Ifs. At this point, the process returns to the powering control corresponding to the accelerator operation amount a2.

The armature adjusting means includes a second switching element 22 connected in parallel with the armature 82 of the DC motor 81 and operating during regeneration, and a power running connected in series with the armature 82 and the second switching element 22. And a rectifying element 2 arranged in reverse polarity in parallel with the first and second switching elements 21 and 22.
3, 24. The control means 40 turns off the second switching element 22 during the powering control and controls the first switching element 21 by chopper control, and turns off the first switching element 21 during the regenerative control. Together with the second switching element 2
2 is chopper-controlled.

The field current adjusting means 30 includes a DC motor 81 at the bridge between the bridge terminals 301 and 302 facing each other.
Switching element 31 connected to the field coil 83 of FIG.
The control means 40 comprises a pair of switching elements (311 and 313) or (311) on opposite sides of the bridge circuit.
2 and 314), one of the two sets
The magnitude and direction of the field current If are controlled by performing chopper control corresponding to one rotation direction and turning off the other set.

In the figure, reference numeral 25 denotes first and second switching elements 21 and 22 based on a command from a control means 40.
A driver circuit 33 drives the field switching elements 311 to 314 based on a command from the control means 40.
321 to 324 are protection diodes for the field switching elements.

The following is a supplementary explanation for each.
First, the relationship between the load torque to be controlled corresponding to the accelerator operation amount ai and the rotation speed (vehicle speed) is shown in FIG.
The relationship is as shown in FIG. That is, for example, as shown by curves 611 to 613 in FIG. 9A, the value of the rotation speed (speed) is inversely proportional to the load torque while limiting the magnitude of the torque at low speed (accordingly, the armature current). Control.

At the time of ordinary power running control, control is performed in accordance with the curves 611 to 613 by basically operating the field current and the armature voltage. Then, when the accelerator operation amount decreases and a new relationship is entered (for example, a transition from the curve 613 to the curve 611), that is, when so-called accelerator-linked regeneration is performed, deceleration control with a constant braking torque is performed, and regeneration control is performed again. The control that shifts from the control to the powering control realizes appropriate control that minimizes control discontinuity so that undershoot does not occur and control delay does not occur, as described in detail later.

First, a control method during the power running operation will be described. In this case, the field current and the armature voltage are controlled while limiting the armature current to a certain value or less.
First, the current load torque T is calculated from the current value of the armature current Ia and the value of the field current If. Then, based on the value T of the load torque, first, an appropriate field current command value Ifo is determined based on, for example, a table that determines the relationship of (T-Ifo) or a calculator.

On the other hand, as described above, the torque speed curve corresponding to the accelerator operation amount ai (curves 611-6 in FIG.
From 13), the rotation speed N of the electric motor with respect to the load torque T is determined. For example, when the accelerator operation amount is a3 and the load torque is T1, the speed N1 is obtained from the intersection of the curve 613 and T1 in FIG. The armature voltage Va and the rotation speed N when the field current is constant at this time are
(B) corresponding to the field current values If1 to If3, and the armature voltage-speed curve (corresponding to the field current command value Ifo). In the figure, the command value Vd of the armature voltage is determined from the curve 622) and the speed N1.

Then, based on the command values Ifo and Vd, the field current and the armature voltage are set to the above-mentioned values so that the values shown in FIG.
As shown in (1), the first switching element 21 and the field switching elements (312 and 314) or (311 and 31)
3) chopper control (field switching element (3
12 and 314) or (311 and 313) is determined by the forward and reverse rotation directions). At this time, the magnitude of the armature current is limited so as to be less than a certain value.

Next, a description will be given of a control method at the time of accelerator-linked regeneration. In this case, as shown in FIG. 6, the accelerator operation amount a decreases from a3 to a1, and the torque-speed curve changes from the curve 613 to 611 in FIG. Then, a point A on the curve 613 corresponding to the current load
From the control to the point B on the curve 611.
The so-called undershoot phenomenon in which the control is reversed from the point B 'to the point B in the curve 611 in the figure does not occur, and the control delay of the curve 611 does not occur because the switching from the regeneration to the power running is too fast. The control target is to switch the control mode from the regeneration to the power running at the point x where the torque is zero.

In the regenerative control before the shift to the power running, while performing the torque constant control so that the braking torque becomes a constant value Tb as shown in FIG. 6, the armature current Ia as shown in FIG. And the energy of the electric motor 81 is regenerated to the power supply 85. In such regenerative control with constant torque, the relationship between the speed (rotational speed N) and the armature voltage Va when the field current is constant corresponds to the field current values If1 to If3. And the curve 631 in FIG.
As indicated by 〜633, a substantially linear relationship is obtained.

FIG. 7B shows field current values If1 to If3.
Armature voltage-rotation speed curves 621-6 during powering corresponding to
FIG. 23 is a diagram showing the armature voltage-revolution speed curves 631 to 633 during regeneration corresponding to field current values If1 to If3 on the same diagram. As a result, as can be seen from the figure, the armature voltage during power running (for example, Vd in FIG. 4) and the armature voltage during regeneration (for example, Vb in FIG. 5) corresponding to the same speed.
And a gap ΔVa that varies depending on the values of the field currents If1 to If3.

In the present embodiment, the command value of the field current is set so that the gap ΔVa of the armature voltage at the rotation speed Nx at the time of the regenerative-powering switching shown in FIG. 6 becomes a minimum (ΔVa in FIG. 7). = ΔVa1, ie, when the field current is If1). As a result, s in FIG.
When the regenerative control indicated by the point is shifted to the powering control indicated by the point x, the change ΔVa of the command value with respect to the armature voltage while the field current is kept constant is extremely small, and no undershoot occurs and the control is not performed. It is possible to shift from regeneration to power running control without delay and reduction in regeneration efficiency. As described above, according to this embodiment, the speed can be controlled by detecting the armature voltage without using the rotation sensor, and the DC shunt for the industrial vehicle can be smoothly shifted from the regeneration to the powering. An electric motor control device can be obtained.

[0031]

As described above, according to the present invention, it is possible to obtain a DC shunt motor control device which does not require a rotation sensor and can perform smooth and efficient regeneration and power running control.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a motor control device according to an embodiment.

FIG. 2 is a diagram illustrating the flow of an armature current and a field current during power running control in FIG. 1 and an operation state of a switching element.

FIG. 3 is a diagram showing the flow of an armature current and a field current during regenerative control in FIG. 1 and an operation state of a switching element.

FIG. 4A is a diagram showing the relationship between the torque and the rotation speed when the operation amount of the accelerator is constant during power running control, and FIG. 4B is a diagram showing the relationship between the armature voltage and the rotation speed when the field current is constant. Figure (b).

FIG. 5 is a diagram showing a relationship between an armature voltage and a rotation speed when regenerative control is performed by constant torque control and a field current is fixed.

FIG. 6 is a diagram showing changes in the rotation speed and the change in torque at the transition from regeneration to power running during accelerator-linked regeneration in the control device of the embodiment.

FIG. 7 is an explanatory diagram showing a change ΔVa in a command value of an armature voltage when the control device of the embodiment shifts from regenerative control at the time of accelerator-linked regeneration to power running control.

FIG. 8 is a connection diagram of a conventional motor control device.

[Explanation of symbols]

 11. . . Armature voltage detecting means, 12, 13. . . 13. current detection means; . . Accelerator sensor, 30. . . 40. field current adjusting means . . Control means,

Claims (3)

[Claims] A voltage detecting means for detecting an armature voltage of a DC shunt motor driving an industrial vehicle; a current detecting means for detecting an armature current and a field current of the DC motor; An accelerator sensor for detecting a neutral state of the direction switch, an armature adjusting means capable of switching the direction of the armature current and adjusting the magnitude of the armature voltage and current, and a field current adjusting means. Calculating the current load torque from the value of the armature current and the value of the field current, and setting the armature adjusting means and the field motor so as to attain a predetermined rotational speed corresponding to the detection signal of the accelerator sensor and the load torque. And control means for operating the current adjusting means, wherein the control means controls the load torque and the accelerator operation amount when the accelerator is depressed. a1 while adjusting the field current and the armature voltage while limiting the armature current to a predetermined value or less so as to achieve a predetermined rotation speed corresponding to a1. A small operation amount a2 from the amount a1
When the operation is returned to, the new accelerator operation amount a2
In order to shift to the relationship between the load torque and the rotation speed corresponding to the above, the electric power of the DC motor is regenerated to the power supply side while being braked at a predetermined constant braking torque Tb.
In the relationship between the load torque during power running and the rotational speed corresponding to the new accelerator operation amount a2, the rotational speed N at zero load torque
The value of the field current is determined in advance so that the value Vd of the armature voltage with respect to d2 and the value of the armature voltage Vb when the rotation speed Nd2 is obtained by braking with the constant braking torque Tb are substantially equal. The value Ifs is set, and the constant braking torque Tb is maintained while the value of the field current is kept constant.
The armature current is controlled so as to become the armature current Ias corresponding to the above. When the armature voltage that decreases with the rotation speed becomes the above-mentioned Vb, the operation is again shifted to the power running control corresponding to the above-mentioned accelerator operation amount a2. A control device for a DC shunt motor for industrial vehicles, which controls the motor. 2. The armature adjusting means according to claim 1, wherein the armature adjusting means is connected in parallel with the armature of the DC motor and is operated at the time of regeneration.
A first switching element connected in series with the switching element and operating during power running; and a rectifying element disposed in parallel with the first and second switching elements with opposite polarities. In the above, the second
The switching element is turned off and the first switching element is chopper-controlled.
The first switching element is turned off and the second switching element is turned off.
A control device for a DC shunt motor for industrial vehicles, wherein chopper control is performed on a switching element. 3. The field current adjusting means according to claim 1, wherein the field current adjusting means comprises a bridge connection circuit of a switching element formed by connecting a field coil of a DC motor to a bridge portion of an opposite bridge terminal. The control means controls the chopper of one of the two sets of the pair of switching elements on the side opposite to each other in the bridge circuit in accordance with the rotational direction and sets the other set to the off state. A control device for a DC shunt motor for an industrial vehicle, characterized by controlling the magnitude and direction of a field current.