JPH04355692A - Speed controller for dc motor - Google Patents

Abstract

PURPOSE:To realize speed control stabilized over the entire speed control region. CONSTITUTION:A shunt controller 19 compares the speed of a DC motor 1 with a basic speed based on a shunt start signal S7 fed from a shunt start setter 18 and a speed signal S1 fed from a speed specifying generator 5. In an enhancing field speed region where the speed of the DC motor 1 is lower than the basic speed, resistance of a variable shunt resistor 21 is maximized to substantially block armature current supply to a series shunt coil 2 thus suppressing increase of torque. In a speed region where the speed of the DC motor 1 is higher than the basic speed, resistance of the variable shunt resistor 21 is decreased through a shunt resistance regulator 20 according to the speed thus increasing the armature current to be shunted to the series shunt coil 2. Consequently, armature reaction is suppressed and torque having magnitude corresponding to the speed can be outputted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor, and more particularly to a speed control device for a DC motor equipped with a shunt series coil for shunting armature current and suppressing armature reaction.

0002

2. Description of the Related Art FIG. 2 is a block diagram showing a conventional example of this type of speed control device.

As shown in the figure, a DC motor (1) is provided with a shunt series coil (2) for shunting armature current in parallel with a compensation winding (3), and a shunt series coil (2) for shunting armature current. 2
) is connected in series with a shunt fixed resistor (4).

[0004] The speed control device for this DC motor (1) is as follows:
A finger speed generator (5) that outputs a speed signal (S1) according to the speed of the DC motor (1), and a thyristor conversion device (7) that converts the output of the AC power supply (6) into DC and supplies it to the armature.
), and a speed signal (S1) from the finger speed generator (5)
The thyristor converter device (7) is configured to control the armature current and thereby the speed based on the thyristor conversion device (7). The control method of this speed control device is called the thyristor Leonard method.

[0005] The control operation of this speed control device will be explained below.
This will be explained together with other configurations.

Generally, in the thyristor Leonard system, when the speed of the motor is low, speed control is performed by changing the voltage applied to the armature, and when the speed of the motor is high, speed control is performed by changing the magnetic flux. The boundary between voltage control and field control is the point where the voltage applied to the armature becomes the full voltage, and the speed at this point is called the base speed.

When the electric motor is operated within the above voltage control range, that is, below the base speed, the following speed control is performed. The speed setting signal (S2) at a level corresponding to the set speed output from the speed setting device (8) and the speed signal (S1) from the finger speed generator (5) are transferred to a speed control amplifier (9). The output of the speed control amplifier (9) is converted into a voltage control signal (S) by the current comparison amplifier (10).
Convert to 3). An armature current detected by a current transformer (11) and converted to an appropriate level by a current converter (12) is negatively fed back to the voltage comparison amplifier (10). Then, in response to the current control signal (S3) of the current comparison amplifier (10), the gate signal generator (13) generates a gate signal (S4).
), and the gate signal (S4) controls the thyristor converter (7) to control the voltage applied to the armature, thereby controlling the speed of the DC motor (1).

[0008] At this time, the field current is controlled to be approximately constant.

Further, when the electric motor is operated within the field control range, that is, above the base speed, the following control is performed. The armature voltage converter (14) sends out an armature voltage detection signal (S5) when the voltage applied to the armature reaches the full voltage. Upon receiving this armature voltage detection signal (S5), the field current controller (16) outputs the speed set by the speed setter (8) and the speed signal (S5) from the finger speed generator (5).
1) to generate magnetic flux according to the field coil (17).
Controls the current flowing to the At this time, the voltage applied to the armature is constant throughout the entire voltage, and the field current is controlled so that the magnetic flux generated by the field coil (17) is approximately inversely proportional to the speed of the motor.

By controlling the voltage applied to the armature and the field current, the speed of the DC motor (1) is controlled by the speed setting device (8).
) can be adjusted to the set speed.

By shunting the armature current of this DC motor (1) to the shunt series coil (2), the reduction in main magnetic flux due to armature reaction is compensated for and the armature reaction is suppressed. .

In the case of the speed control device having the above configuration, the shunt series coil (2) has a constant shunt current determined by its own impedance and the impedance of the shunt fixed resistor (4) and the compensation winding (3). The current is a DC motor (1
) will flow over the entire velocity range.

[0013]

In the conventional speed control device, as described above, a constant shunt current flows through the shunt series coil (2), so the magnetic flux generated thereby is constant. However, armature reaction increases as speed increases. Therefore, even in the region below the base speed where it is not necessary to suppress the armature reaction, a shunt current flows through the shunt series coil (2), and the torque tends to increase relative to the predetermined speed. This will give extra driving force to the load device. Further, even in the range above the base speed, the shunt current to the shunt series coil (2) is constant, so torque corresponding to the speed cannot be obtained.

As described above, the conventional speed control device generates a field that matches the decrease in the main magnetic flux due to the armature reaction, and cannot cancel out the armature reaction in the entire speed range. There was a problem in that desired torque characteristics with respect to speed could no longer be obtained.

The present invention was made to solve this problem, and stabilizes the DC motor that drives the load device by generating a magnetic flux of a magnitude corresponding to the armature reaction over its entire speed range. It is an object of the present invention to provide a speed control device that can obtain torque characteristics that are as follows.

[0016]

[Means for Solving the Problems] In order to achieve the above object, the speed control device according to the present invention includes a diversion start setting device that outputs a diversion start signal at a preset constant level, and a diversion start setting device that outputs a diversion start signal at a preset constant level. The level of the shunt start signal from the finger speed generator is compared with the level of the speed signal from the finger speed generator, and when the level of the speed signal is higher than the level of the shunt start signal, the shunt control signal is set at a level corresponding to the level of the speed signal. a shunt control device that outputs a shunt current, a shunt variable resistor that limits the shunt current flowing to the shunt series coil, and a shunt variable resistor that reduces the resistance value of the shunt variable resistor as the level of the shunt control signal from the shunt control device increases. A shunt resistance adjustment device was provided to adjust the current flow.

[0017]

[Operation] According to the above configuration, in the region where the speed of the DC motor is lower than the speed corresponding to the level of the shunt start signal of the shunt start setting device, the resistance value of the shunt variable resistor becomes maximum, and the resistance value of the shunt series coil is , the armature current is almost not shunted. Therefore, in this speed range, an increase in torque is suppressed and a predetermined relationship between speed and torque is obtained. Also,
In a region where the speed of the DC motor is higher than the speed corresponding to the level of the shunt start signal, the resistance value of the shunt variable resistor decreases in accordance with the speed of the DC motor, and the armature to the shunt series coil decreases accordingly. The shunt current of the current increases. Therefore, in this speed range, the armature reaction is suppressed and a torque corresponding to the speed of the DC motor is output.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a speed control device according to the present invention. In FIG. 1, the same reference numerals are given to the same components as in the conventional example shown in FIG. 2, and the explanation thereof will be omitted.

As shown in the figure, the difference in the configuration of this speed control device from the conventional example is that a shunt start setting device (18), a shunt flow control device (19), and a shunt resistance adjustment device (20) are newly provided. , instead of the shunt fixed resistor in the conventional example, a shunt variable resistor (21) is connected in series to the shunt series coil (2).

The shunt start setting device (18) outputs a shunt start signal (S7) at a constant level. In this case, the level of the shunt start signal (S7) is equal to or lower than that of the DC motor (1). Corresponding to the base speed, that is, the DC motor (1
) is set to the same level as the speed signal (S1) output from the finger speed generator (5) when the speed is the base speed.

The shunt control device (19) compares the level of the shunt start signal (S7) from the shunt start setting device (18) with the level of the speed signal (S1) from the finger speed generator 5. , the level of the speed signal (S1) is equal to the shunt start signal (S
7), a shunt control signal (S8) of a level corresponding to the level of the speed signal (S1) is output.

The shunt resistance adjustment device (20) operates only when the shunt control signal (S8) is output from the shunt control device (19), and adjusts the resistance value of the shunt variable resistor (21) to The adjustment is made so that the higher the level of the shunt control signal (S8) is, the lower it is.

Furthermore, there is no shunt control signal (S8) from the shunt control device (19), and this shunt resistance adjustment device (20
) does not operate, the above shunt variable resistor (21)
The resistance value of becomes maximum.

Next, the control operation for the shunt current to the shunt series coil (2), which is a feature of the speed control device having the above configuration, will be explained. Note that the speed control of the DC motor (1) by controlling the voltage applied to the field coil (17) and the armature current of this speed control device is the same as in the conventional example, so a description thereof will be omitted here.

When the speed of the DC motor (1) is below the base speed, the level of the speed signal (S1) from the finger speed generator (5) is equal to the shunt start signal (S1) from the shunt start setting device (18).
Since the level is below the level of S7), the shunt control device (19)
does not output the shunt control signal (S8), and the shunt variable resistor (
21) has the maximum resistance value. Therefore, almost no armature current is shunted to the shunt series coil (2).

[0027] As a result, in a speed range below the base speed in which there is no need to suppress armature reaction, the increase in torque is suppressed, and no extra driving force is applied to the load device.

Furthermore, when the speed of the DC motor (1) is higher than the base speed, the speed signal (
Since the level of S1) becomes higher than the level of the shunt start signal (S7) from the shunt start setting device (18), the shunt control device (19) outputs the shunt control signal at a level corresponding to the level of the speed signal (S1). (S8), and accordingly the resistance value of the shunt variable resistor (21) is changed to the shunt resistance adjustment device (20
) decreases due to the action of Therefore, the shunt current of the armature current to the shunt series coil (2) increases depending on the speed of the DC motor (1).

The value of the shunt current to this shunt series coil (2) is determined by the shunt control device (19) so as to sufficiently compensate for the decrease in the main magnetic flux at each speed of the DC motor (1). and is appropriately set by a shunt resistance adjustment device (20) and a shunt variable resistor (21).

[0030] As a result, in a speed range where the speed of the DC motor (1) is higher than the base speed, the decrease in main magnetic flux due to armature reaction is compensated for depending on the speed, and a torque corresponding to the speed is generated. It will be output.

As described above, this speed control device controls the shunt current to the shunt series coil (2) for the DC motor (1) that drives the load device in accordance with the speed of the DC motor (1). By doing so, stable torque characteristics can be obtained over the entire speed range.

[0032]

[Effects of the Invention] As explained above, according to the speed control device of the present invention, for the DC motor driving the load device,
It is possible to obtain stable torque characteristics over the entire speed range.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a speed control device according to the present invention.

FIG. 2 is a block configuration diagram showing a conventional example.

[Explanation of symbols]

(1) DC motor (2) Shunt series coil (5) Finger speed generator (18) Diversion start setting device (19) Diversion control device (20) Shunt resistance adjustment device (21) Shunt variable resistor

Claims (1)

[Claims] [Claim 1] For a DC motor equipped with a shunt series coil that shunts armature current and suppresses armature reaction,
The speed of the DC motor is controlled by providing a finger speed generator that outputs a speed signal corresponding to the speed of the DC motor, and controlling the armature current based on the speed signal from the finger speed generator. In the control device, a diversion start setting device outputs a diversion start signal at a preset constant level, and the level of the diversion start signal from the diversion start setting device is compared with the level of the speed signal from the specified speed generator. , a shunt control device that outputs a shunt control signal at a level corresponding to the level of the speed signal when the level of the speed signal is higher than the level of the shunt start signal; and a shunt that limits the shunt current flowing through the shunt series coil. A speed control for a DC motor, comprising a variable resistor and a shunt resistance adjustment device that reduces the resistance value of the shunt variable resistor as the level of the shunt control signal from the shunt control device increases. Device.