JPH02261091A - Dc motor controller - Google Patents

Abstract

PURPOSE:To detect a motor lock quickly by detecting a position through generating a pulse, whenever the movable part of DC motor moves at a specified distance, and by inputting said pulse to two charge-and-discharge circuits with a specified time constant. CONSTITUTION:One of both ends of a moving-coil type linear DC motor 21 is connected with the positive electrode of a power supply 23 via relay bridge circuit 22 and the other thereof is earthed further via a CT 24, FET 25. Said CT 24 generates a pulse, whenever the movable part of DC motor 21 moves at a specified distance. Said pulse of the CT 24 is waveform-shaped 26 and inputted to charge-and-discharge circuits 27, 28 with a specified time constant. In said circuit 27, a charged capacitor C1 discharges for every pulse from the CT 24. In the circuit 28, a charged capacitor C2 normally discharges in the same way as the capacitor C1, but when the pulse does not come from the CT 24, the voltage of said capacitor C2 rises and an exciting stop circuit 29 outputs power to cut OFF FET 25.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a control device for a DC motor, and particularly to a device suitable for controlling a moving coil type linear DC motor.

"Prior Art" Linear DC motors are sometimes used to open and close residential or vehicle curtains. Curtain opening/closing control requires control to reliably stop the motor when the curtain is completely open or closed.

Furthermore, from the standpoint of safety, it is not desirable to use a motor that exerts excessive thrust, so control is required to protect the motor in the event that the curtain gets caught on something during opening or closing and the motor becomes locked.

Conventional control devices of this type have a timer that detects the energization time after the start of operation and uniformly stops energization after a predetermined time has elapsed, which serves both to control curtain opening/closing and to protect when the motor locks. .

In addition, some curtains have a limit switch installed at the curtain stop position to detect the opening/closing position and stop energizing the motor. Furthermore, some motors are equipped with a current detection element to detect an increase in current due to motor lock and stop the current supply.

[Problem to be solved by the invention J] However, in the case of using a timer, due to variations in operating speed, the time may elapse before the curtain is finished opening or closing, or conversely, the locking current to the motor may take too long at the opening/closing end. There was a problem that there were things to do. Further, those using a limit switch have the problem that the limit switch needs to be installed and wired, making the structure complicated. A problem with detecting lock current is that it requires a special element such as a shunt resistor.

The present invention has been made in view of the above problems, and its first purpose is to detect locking (stopping) of a motor by using a simple speed control device and without providing any special external members. An object of the present invention is to provide a control device for a DC motor that can cut off lock current. The second purpose is to enable opening and closing operations with a single touch of a switch without installing an external limit switch when using a DC motor to open and close curtains, etc., and to ensure that the motor operates at the opening and closing ends. The object of the present invention is to provide a control device that can be stopped.

"Means for Solving the Problem" In order to achieve the above object, the present invention provides a position detection means for detecting a signal that changes every predetermined movement distance of a movable part of a DC motor, and an output signal of the position detection means. a first charging/discharging circuit that is charged at a predetermined time constant and discharged by the pulse signal; and a charging voltage of the first charging/discharging circuit. a drive current control circuit that controls the drive current to the DC motor according to the method; a second charging/discharging circuit that is charged at a predetermined time constant and discharged by the pulse signal; and charging of the second charging/discharging circuit. There is provided a control device for a DC motor, comprising: an energization stop circuit that outputs a signal to the drive current control circuit to cut off the drive current when the voltage exceeds a predetermined voltage.

Further, as a second invention, there is provided a position detecting means for detecting a signal that changes every predetermined movement distance of the movable part of the DC motor, and a pulse signal that outputs a pulse signal in response to a change in the output signal of the position detecting means. an output means, a first charging/discharging circuit that is charged at a predetermined time constant and discharged by the pulse signal, and a drive current control that controls a drive current to the DC motor according to the charging voltage of the first charging/discharging circuit. a relay bridge circuit that switches connection and connection polarity between the drive current control circuit and the DC motor, a timer circuit that outputs a timer signal of a predetermined time width in response to input of the pulse signal, a start switch, and the start switch. A control device for a DC motor is provided, comprising: a relay holding circuit that starts holding the relay bridge circuit closed in response to a signal from the relay bridge circuit and releases the holding when the timer signal disappears.

As the position detection means, for example, a current transformer that detects periodic changes in armature current can be used.

"Operation" In the control device configured as described above, a pulse signal having a frequency proportional to the speed of the DC motor is generated, and the charging/discharging circuit is discharged at that frequency. And the first
The drive current is controlled according to the charging voltage of the charging/discharging circuit, and the speed of the motor is controlled to be substantially constant.

In the first invention, when the DC motor is locked and stopped, the pulse signal is no longer generated, no longer discharged, and the voltage of the second charging/discharging circuit increases, cutting off the drive current.

In the second invention, once the start switch is operated, the relay bridge circuit is held closed by the relay holding circuit, and the DC motor starts moving.

For example, in an example used to drive curtains to open and close, opening and closing of the curtains is started. When the curtain opening/closing is completed and the DC motor is locked and stopped, the pulse signal will no longer be generated. As a result, the timer signal disappears after a predetermined period of time, the relay bridge circuit is no longer held, and the energization of the DC motor is terminated. That is, the relay bridge circuit is held by the relay holding circuit only while the DC motor is moving.

"Example" Embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a cutaway perspective view showing a moving coil type linear DC motor to which the present invention is applied.

The rail 1 has a substantially inverted U-shaped cross section and is constructed of an extruded section made of a non-magnetic material such as aluminum. rail 1
A magnet holder 2 is formed on the inner surface of one side, and a large number of flat permanent magnets 3 are arranged in the magnet holder 2. The flat permanent magnets 3 are magnetized in the thickness direction, and are inserted and arranged in the magnet holder 2 so that the polarity is sequentially alternated. Further, a plate-shaped yoke 4.5 is inserted between the back surface of the permanent magnet 3 and the inner surface of the side wall of the rail 1, and on the inner surface of the other side wall of the rail 1, respectively, to form a magnetic path.

A power supply pattern 9 made of a printed circuit board is attached to the yoke 5 facing the movable coil section 6. The magnet holding section 2 also has the function of an inner rail that guides the movable coil section 6 in the longitudinal direction.

The movable coil section 6 is constructed by two coils 7.8 arranged side by side in the longitudinal direction and integrally molded with resin. It is shaped to fit within the rail 1. Each coil 7.8 is wound in a substantially rectangular shape and flattened, as shown by the dot-dash line in the figure. A current collecting brush 7A is provided to protrude from the back surface of the movable coil section 6.

Power is supplied to each coil 7.8 from 7B, 8A, and 8B, respectively.

Each coil 7.8 is wound so that the width in the longitudinal direction of one side of its flat winding portion is approximately 0.5 times the length of the permanent magnet 3, and the length of each coil 7.8 is approximately 0.5 times the length of the permanent magnet 3. Its length (total width) is 1.5 times that of the permanent magnet 3, and it has a space (air core part) that is 0.5 times as long as the permanent magnet 3 in the center. Therefore, the distance between the centers of the two coils 7.8 is 1.5 times that of the permanent magnet 3.

The upper and lower ends of each coil 7.8 are bent, and the movable coil portion 6 has a U-shaped cross section, and the bent portion engages with the side surface of the magnet holding portion 2 at a sliding portion = 8. I am...

The movable coil portion 6 is connected to each coil 7.8 from the power supply pattern 9 via current collection brushes 7A, 7B, 8A, and 8B.
A current with a polarity corresponding to the position is supplied, and as shown in FIG. 3, the movable coil portion 6 is driven in the longitudinal direction by the electromagnetic force with the magnetic flux φ generated by the permanent magnet 3.

FIG. 4 is a schematic diagram illustrating the pattern of the power supply pattern 9 and the operation of the linear motor.

The power supply pattern 9 is formed of a printed circuit board and has two conductive parts 9A and 9B. Conductive part 9Δ.

9B, when the effective winding part of each coil 7.8 is completely within the magnetic flux of one permanent magnet 3, current is applied to each current collecting brush 7A, 7B or 8A, 8B, and the polarity of the magnetic flux is reversed. The pattern is formed so that the feeding polarity is reversed when

The dashed dotted line 11 in the figure indicates each current collecting brush 7A, 8A and 7B.
, 8B. Each conductive part 9A, 9B is connected to a DC power supply 13 via an operation switch 12.

Then, the current collecting brushes 7A, 7B, 8A, 8B and the conductive part 9
As the movable coil section 6 moves by sliding contact and separation with A and 9B, the coils 7 and 8 are alternately excited, and the direction of the exciting current of each coil 7.8 is sequentially reversed. In this way, as the movable coil section 6 moves, each coil 7.
The direction of the excitation current is switched according to the direction of the magnetic flux at the location where F
, and slide in the longitudinal direction. In addition, the movable coil section 6
The conductive part 9A is used to switch the direction of movement of the conductive part 9A.

Just change the polarity of 9B. Here, one coil 7
In order to avoid a situation in which both coils 7.8 are not excited when excitation is switched from one coil to the other coil 8, the conductive portion 9A of the power feeding pattern 9, 9B is formed.

Therefore, the total current of the linear motor supplied from the power supply 13 to the power supply pattern 9 becomes a current that changes stepwise every time the movable coil section 6 moves a predetermined distance, as shown in FIG. 4(f). The embodiment of the present invention attempts to control the speed of a moving coil type linear DC motor by detecting this current change.

FIG. 1 is a circuit diagram showing an embodiment of the first invention. Both ends of the moving coil type linear DC motor 21 (specifically, the conductive parts 9A and 9B of the electrical connection pattern 9) are connected to the relay bridge circuit 22, one terminal of which is connected to the positive electrode of the power supply 23, and the other terminal is a current transformer (current transformer CT) 24. Field effect transistor 25 (hereinafter referred to as FET2)
5) is connected to the negative electrode of the power supply 23 via the drain and source thereof, and is grounded.

The current transformer 24 detects a change in the drive current (2) of the linear DC motor 21, and generates a pulse signal in the secondary winding at the timing when the drive current changes stepwise. The current transformer 24 includes a position detection means for detecting a signal (current) that changes every predetermined movement distance of the movable part 6 of the DC motor 22, and outputs a pulse signal in response to a change in the output signal of the position detection means. It also serves as a pulse signal output means.

As shown in FIG. 5, the FET 25 constitutes a drive current control circuit that controls the drive current (1) of the linear DC motor 21 in accordance with the potential applied to its gate.

One end of the secondary winding of the current transformer 24 is grounded, and the other end, where a pulse signal is generated, is connected to a waveform shaping circuit 26.

The waveform shaping circuit 26 includes diodes D1.
Input resistance R1, R, 2, resistance R3 providing L threshold voltage
, R4, and a comparator ICI having an open collector output stage, and shapes the signal from the current transformer 24 to output a pulse signal.

The output of the waveform shaping circuit 26 is connected to a first charging/discharging circuit 27 and a second charging/discharging circuit 28 .

The first charging/discharging circuit 27 includes a capacitor C1 whose one end is grounded, a variable charging resistor R5 that connects the capacitor C1 and a constant voltage source V, and a comparator IC that charges the capacitor C1.
It consists of a discharge resistor R6 that discharges through an open collector transistor in I, and a diode D2. Capacitor C1 is connected to the gate of FET 25 via resistor R112. In the first charge/discharge circuit 27, the capacitor C1 is constantly charged through the charging resistor R5, and when a positive pulse is input from the current transformer 24, the oven collector transistor in the comparator T C1 becomes conductive. and the capacitor C1 is discharged.

The second charging/discharging circuit 28 includes a capacitor C2, a charging resistor R
8, a discharging resistor R7, and a diode D3, the capacitor C2 is continuously charged through the charging resistor R8, and the capacitor C2 is discharged simultaneously with the first charging/discharging circuit 27 by the pulse signal from the waveform shaping circuit 26. Ru. Capacitor c2 is connected to a current cutoff circuit 29.

The energization stop circuit 29 includes a comparator IC2 having an oven collector output stage, resistors R9 and RIO that apply a predetermined threshold voltage to the comparator IC2, and an output resistor R11. The voltage of the capacitor c2 from the second charging/discharging circuit 28 is input to the input of the comparator IC2, and the output is from the resistors R,1,
1 to the first charging/discharging circuit 27 and ri'ET
' Connected to the connection point with 25.

FIG. 6 is a time chart explaining the operation. When the relay bridge circuit 22 is closed in either direction, the drive current I of the linear DC motor 2 rises, and a thrust is generated in the moving coil section 6, causing it to move in either direction (see Fig. 6 (a).
)). Then, as the movable coil section 6 moves, the motor drive current ■ changes stepwise at regular intervals (sixth
Figure (b)). The frequency of this current change is proportional to the running speed of the moving coil section 6. The current transformer 24 generates positive and negative pulse signals in response to stepwise changes in the motor drive current I (FIG. 6(C)). Only the positive pulse signal is shaped and output by the waveform shaping circuit 26, and the output transistor of the comparator IC1 is rendered conductive by this positive pulse signal (FIG. 6(d)). In the first charging/discharging circuit 27, the capacitor C1 is connected to the charging resistor R5 when the comparator IC1 is off.
It is charged with a charging time constant 01.R5 determined by the resistance value of R6, and discharged with a discharging time constant 01.R6 determined by the resistance value of the discharging resistor R6 when the comparator ICI is on. Discharge time constant 01・
Since R6 is set very short, capacitor C1 is immediately discharged when comparator IC1 is turned on. The charging voltage of the capacitor C1 (potential at point A) is as shown in FIG. 6 (g>).

Here, if the running speed of the moving coil section 6 of the linear DC motor 21 is slow and the cycle in which the comparator ICI is turned on is longer than the charging time constant 01.R5, the charging voltage (potential at point A)
The average value of becomes higher. Therefore, the voltage applied to the gate of the FET 25 becomes higher, and as shown in FIG. 5, the motor drive current (2) increases, more thrust is generated, and the movable coil section 6 tries to move faster. On the other hand, if the traveling speed of the moving coil section 6 is fast and the cycle in which the comparator C1 is turned on is shorter than the charging time constant 01.R5, the average value of the charging voltage (potential at point A) becomes low, and the gate of the FET 25 The voltage decreases and the motor drive current 1 decreases. Therefore, the thrust force decreases and the traveling speed decreases.

In this way, periodic changes in the motor drive current I can be detected, the speed can be fed back, and the speed can be controlled to correspond to the charging time constants 01 and R5.

The speed can be easily adjusted by adjusting the resistance value of the charging resistor R5 and changing the charging time constant 01·R5. When the charging resistance value R5 is increased, the speed becomes slower,
If the charging resistance value R5 is made small, the speed becomes faster. That is, current transformer 24°FET25. Waveform shaping circuit 26. The first charge/discharge circuit 27 constitutes a simple speed control circuit.

The second charge/discharge circuit 28 and the energization stop circuit 29 cut off the drive current I when the motor 21 is locked and stopped.

The second charge/discharge circuit 28 is constantly charged with a charging time constant of 02.R8, and when the comparator ICI is on, the discharging time constant is 02.
・Discharged at R7. The discharge time constant 02.R7 is set quite short, and the charging voltage of the capacitor C2 (voltage at point B) becomes as shown in FIG. 6(e).

When the moving coil section 6 of the linear DC motor 21 is running, the capacitor C2 is discharged every pulse signal from the current transformer 24, and the voltage at point B does not become very high.

However, if the moving coil 6 is locked to something and stops moving, the pulse signal will no longer be generated. Therefore, it is no longer discharged, and the charging voltage of capacitor C2 increases,
This exceeds the threshold voltage Vc at the 0 point. As a result, the output transistor in the comparator IC2 is rendered conductive (FIG. 6(f)). Then, the capacitor C1 of the first charging/discharging circuit 27 is forcibly discharged by the transistor in the comparator IC2, and the potential at point A is changed to the time constant 01·R, 11
It is rapidly dropped to earth level (0■). As the potential at point A decreases, the gate voltage of the FET 25 decreases, and the motor drive current (2) is cut off.

Note that the charging time constant 02·R8 of the second charging/discharging circuit 28 is selected to an appropriate value so that the voltage at point B does not reach the threshold voltage Vc during normal driving.

The frequency of the pulse signal during normal running is several tens to several hundred Hz, and the appropriate charging time constant 02.R8 is about 0.1 to .1see.

FIG. 7 is a block diagram showing an embodiment of the second invention.

This circuit is used to directly drive the hooks of the curtain with the movable coil 6 of the linear motor 21 and to control the opening and closing of the curtain.

A current transformer 24, a drive current control circuit (FET) 25, and a waveform shaping circuit 2 that constitute a simple speed control circuit 30
6. The first charging/discharging circuit 27 is the same as that described in FIG. 1 above. In this embodiment, the start switch 4
A relay holding circuit 43 and a timer circuit 44 are added to hold the relay bridge circuit 22 by a signal from 1.42.

As shown in FIG. 8, the relay bridge circuit 22 is composed of two relays Ryl and Ry2, and is a circuit that supplies current to the linear motor 21 in the forward or reverse direction by exciting either relay. .

As shown in FIG. 9, the relay holding circuit 43 is a relay circuit that closes and holds either relay R3'l or Ry2 by operating the open start switch 41 or the close start switch 42, and is a timer circuit. The relay Ry3 is self-maintained only while the relay Ry3 is energized by the signal from 44. Further, the self-holding state is released by operating the stop switch 45.

The timer circuit 44 is a short-time triggerable one-shot timer circuit, and outputs a timer signal with a predetermined pulse width upon input of the pulse signal from the waveform shaping circuit 26, thereby closing the relay Ry3. If the next pulse signal is input within the predetermined pulse width, the timer signal becomes a continuous output.

FIG. 10 is a time chart diagram explaining the operation.

By pressing the start switch 41, the relay Ryl
is opened, and power supply to the linear motor 21 is started (Fig. 1O (a), (b)). When the movable coil 6 of the linear motor 21 starts running, the drive current 2 changes in a pulse-like manner, and a pulse signal is output from the waveform shaping circuit 26 (FIGS. 10(b) and 10(c)). Due to the generation of the pulse signal, a timer signal is output from the timer circuit 44, and relay R
y3 is closed and the power supply relay Ryl is self-held (
Figure 10(d).

(e)). The frequency of pulse signals during normal driving is several dozen to
The frequency is several hundred Hz, and the time from when the start switch 41 is pressed to when the self-holding occurs is hardly a problem. As long as the movable coil 6 is moving, pulse signals are generated one after another, and the self-holding of the relay Ryl continues.

Eventually, when the opening of the curtain is completed and the movable coil 6 reaches the end of the rail 1 and stops, the pulse signal is no longer generated, and after the time T of the predetermined pulse width of the timer circuit 44 has elapsed, the timer signal disappears, and the relay Ry3 is dropped and the self-holding of power supply relay Ry1 is released. As a result, power supply to the linear motor 21 is stopped.

This embodiment has the following advantages6: Once the start switch 41 or 42 is pressed, the opening/closing operation of the curtain is started, and as long as the curtain is moving, it is self-maintained. There is no time-up during opening/closing and the product does not stop working.

Energization to the linear motor 21 can be reliably terminated at the end of the rail 1 without providing a limit switch or the like on the rail 1. Also, if the curtain gets caught on something while opening or closing and becomes stuck, immediately turn the motor 21
Since the power supply to the lock is cut off, the lock power supply time is shortened.

Only a small number of circuits are added to the speed control circuit 30, resulting in little cost increase.

"Effects of the Invention" Since the present invention has the above-mentioned configuration, it has the effect that when the running of the motor is locked, the stoppage can be directly detected and the power supply to the motor can be immediately cut off. be.

In addition to the above-mentioned effects, the second invention maintains the energization of the motor only while the motor is moving, and immediately cuts off the energization when the motor is locked to something and stops moving. can. This effect is extremely suitable for application to curtain opening/closing control.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, FIG. 1 is a circuit diagram showing the first embodiment of the invention, FIG. 2 is a cutaway perspective view showing a linear DC motor to which the present invention is applied, and FIG. 3 shows essential parts. FIG. 4 is a schematic diagram illustrating the operation of the linear DC motor, FIG. 5 is a graph diagram illustrating the operation of the drive current control circuit (FET), and FIG. 6 is a diagram illustrating the operation of the embodiment device. FIG. 7 is a block diagram showing an embodiment of the second invention, FIGS. 8 and 9 are circuit diagrams, and FIG. 10 is a time chart showing the operation. 111. Linear motor rail, 63. , moving coil section, 21 , linear DC motor, 22 , ,
Relay bridge circuit, 24, current transformer (CT
), 25 , , drive current control circuit (FET), 26
, , Waveform shaping circuit 27 , First charge/discharge circuit 28 , Second charge/discharge circuit 29 , Energization stop circuit 4.1, 42. ,,start switch,
43. Relay holding circuit; 44. Timer circuit. ＾4- 0 く 連 綜 0 - Ｇａｎｔｅｎｄｅｒ） Diagram (a) Start switch (b) Drive current (c) Pulse signal (d) Timer signal (e) Self-holding Ry3 - 111111

Claims (1)

[Scope of Claims] 1. Position detection means for detecting a signal that changes every predetermined movement distance of the movable part of the DC motor, and a pulse signal output that outputs a pulse signal in response to a change in the output signal of the position detection means. means, a first charging/discharging circuit that is charged at a predetermined time constant and discharged by the pulse signal, and a drive current control circuit that controls the drive current to the DC motor according to the charging voltage of the first charging/discharging circuit. a second charging/discharging circuit that is charged at a predetermined time constant and discharged by the pulse signal; and a signal is sent to the drive current control circuit when the charging voltage of the second charging/discharging circuit exceeds a predetermined voltage. A control device for a DC motor, comprising: an energization stop circuit that outputs a current and cuts off a drive current; 2. A position detection means for detecting a signal that changes every predetermined movement distance of the movable part of the DC motor, a pulse signal output means for outputting a pulse signal in response to a change in the output signal of the position detection means, and a pulse signal output means for outputting a pulse signal at a predetermined time. a first charge/discharge circuit that is charged at a constant rate and discharged by the pulse signal; a drive current control circuit that controls the drive current to the DC motor according to the charging voltage of the first charge/discharge circuit; and the drive current control circuit. A relay bridge circuit that switches connection and connection polarity between the circuit and the DC motor, a timer circuit that outputs a timer signal of a predetermined time width in response to input of the pulse signal, a start switch, and a signal from the start switch that controls the relay bridge. A control device for a DC motor, comprising: a relay holding circuit that starts holding the circuit closed and releases the holding when the timer signal disappears.