JPS61288791A - Motor control circuit - Google Patents

Abstract

PURPOSE:To prevent a DC motor from heating and brushes from deteriorating, by switching the power gain of a power supply circuit to a low gain at initial position setting time. CONSTITUTION:A controller 5 outputs a speed command of direction A, a rotating direction command and a gain switching command, and closes a switch element 8. Thus, a speed deviation signal generator 6 supplies a speed deviation signal through an amplifier 11 to a power supply unit 12. When the projection 1a of a movable member 1 contacts a stopping lever 2, a DC motor 3 becomes a forcibly stopping state. Since the gain of the amplifier 11 drops at this time, a small current flows through the motor 3. When the fact that the motor 3 is in the forcibly stopping state is detected, the motor is moved to the initial position to be positioned. Thus, it can prevent the motor from overheating and brushes from deteriorating.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor control circuit that controls the rotational speed and positioning of a DC motor.

Conventional technology In recent years, DC motors and motor control circuits have come to be used in the mechanism operations of information devices such as electronic typewriters and printers, as demands for higher speed operation and improved positioning accuracy have increased. . Further, in a mechanism using a DC motor, an initial position setting operation is required to accurately set an initial position that serves as a reference position for its operation.

A conventional motor control circuit will be described below with reference to the drawings. FIG. 6 shows a conventional motor control circuit. In FIG. 6, 1 is a movable member, 1a is a protrusion, and 2
3 is a stop lever, and 3 is a DC motor that drives the movable member 1. 4 is directly or indirectly coupled to the rotating shaft of the DC motor 1, and as the DC motor 1 rotates, a position signal, which is two pseudo sine waves having a phase difference of π/2, is sent to the terminal a and to the terminal A. The position detectors o19 that apply voltage are terminals 1 and 1, respectively. It is equipped with a terminal i and a terminal k, and inputs a position signal which is two pulse signals generated based on the above two position signals and applied to the terminals i and terminal j, and presets based on the above position pulse. According to a series of control procedures, a rotation direction command indicating the direction in which the DC motor 3 should rotate is output to terminal i, and a digital signal 67, -1 speed command indicating the target speed at which the DC motor 3 should rotate to terminal k. It is a control device.

6 inputs the two position signals, the speed command, and the rotation direction command, and corresponds to the rotation direction command in proportion to the difference between the actual rotation speed of the DC motor 3 and the target speed indicated by the speed command. This is a speed deviation signal generator that generates a speed deviation signal having a polarity of 1, and also outputs the above two position pulses to a terminal i. When the speed command indicates zero, the switch 8 is turned off and the switch 9 is turned on to control the positioning of the DC motor 3. When the speed command indicates a value other than zero, the switch 7 is turned off. This is a switch switching circuit that turns on the switch 8 and turns off the switch 9 to set the speed control state in which the rotational speed of the DC motor 3 is controlled. Reference numeral 13 denotes a phase compensator that advances and compensates the position signal applied to terminal a so that the motor control circuit obtains sufficient stability. 2o is a power supply circuit, 21 is an amplifier which receives the speed deviation signal as input via switch 8, and 12 is an output of amplifier 21 and a phase 67, -1 output of compensator 13 via switch 9. The circuit configuration of the zero-order amplifier 21, which is a power supply device that receives power as an input and supplies power to the DC motor 3, will be described. 14 is an operational amplifier whose non-inverting input is grounded and whose inverting input terminal is connected to the output of the operational amplifier 14 via a resistor 16 and to the switch 8 via the resistor 16.

The operation of the motor control circuit configured as above will be explained below. The control operation includes a normal operation consisting of a speed control state and a positioning control state that control the rotational speed of the DC motor 3, and an initial position setting operation that sets the DC motor 3 to an initial position that is the reference position during the normal operation. . First, the above normal operation will be explained. In the following explanation, the above two position signals applied to terminal a and terminal S are respectively va and b, and the above two position pulses applied to terminal l are respectively Ph and P, and the above speed deviation is It is assumed that the signal is v6 and the current supplied by the power supply circuit 20 to the DC motor 3 is 2o. First, when the control device 19 outputs the speed command indicating a value other than zero and the rotation direction command indicating the direction A in Fig. 671.7, the switch changeover circuit 7 puts the motor control circuit in the speed control state, and the DC motor 3 Rotation is started upon receiving power from the power supply circuit 2o, and the movable member 1 is driven in the in direction of FIG. 6.

The position detector 4 generates the two position signals V, , Vb as shown in FIG. 6 as the DC motor 3 rotates, and the speed deviation signal generator 6 generates the position signals V, , Vb and the speed command. , the speed deviation signal v6 based on the rotation direction command.
is output and transmitted to the input of the power supply circuit 2° via the switch 8. The relationship between the speed deviation signal v6 and the current I2o that drives the DC motor 3 in the A direction is as shown in FIG. 7, and if the actual speed of the DC motor 3 is lower than the target speed indicated by the speed command, the speed deviation When the polarity of the signal v6 becomes positive, the DC motor 3 is accelerated in the input direction according to the characteristics shown in FIG. 7, and if the actual speed is higher than the target speed, the DC motor 3 is accelerated in the B direction shown in FIG. It is accelerated in the incoming direction, that is, decelerated in the incoming direction. Therefore, the speed of the DC motor 3 is controlled so that it rotates at the target speed. On the other hand, the control device 19 calculates the amount of movement of the movable member 1 by counting the position pulses Ph or P, and when the movement of the target distance is completed, outputs zero to the speed command,
When the switch switching circuit detects that the speed command becomes zero, it switches the switch 7 to the on state and the switch 8 to the off state, that is, to the positioning control state.

The position signal va is subjected to advance compensation by the phase compensator 13 and then transmitted to the power supply circuit 20. The power supply circuit 20 accelerates the DC motor 3 in the direction B in FIG. 6 when the polarity of the position signal is positive, and in the inward direction when the polarity is negative. Therefore, the DC motor 3 is controlled to be positioned at the zero cross point of the position signal va.

As described above, in the normal operation, the control device 19 moves and positions the movable member 1 from an arbitrary position to an arbitrary position by counting the amount of movement of the movable member 1. Therefore, prior to the normal operation, the movable member 1 is moved. It is necessary to perform an operation for positioning at an initial position that is a preset reference, and an initial position setting operation.〇9 A-; The above initial position setting operation will be explained below.〇The control device 19 is operated by the input shown in Fig. 6. The above-mentioned speed command and rotation direction command are output, and the speed control is performed on the DC motor 3 to drive the movable member 1 in the input direction.

Eventually, the protrusion 1a of the movable member 1 hits the stop lever 2, as shown in FIG. 2, and the movement in the inward direction is forcibly blocked, and the DC motor 3 is also forcibly stopped.

As shown in FIG. 6, the control device 19 detects that the protrusion 1a is in contact with the stop lever 2 because the two position pulses Ph or Pi do not rise or fall for a certain period of time, and also detects that the projection 1a is in contact with the stop lever 2. The movable member is moved in the direction of the DC motor 3 from the above two position pulses Ph and P, positioning control is performed, and the initial position setting operation is completed.

Problems to be Solved by the Invention However, with the above configuration, when the DC motor 3 is forcibly stopped during the initial position setting operation,
The speed of the DC motor 3 remains under speed control 1073, but the actual speed of the DC motor 3 becomes zero, and the speed deviation signal v6 takes an excessive value, so the operating point of the power supply circuit 2o changes. As shown at point E in FIG. 7, the power supply circuit 2° supplies the maximum current IE that can be supplied to the DC motor 3 as shown in FIGS. will generate the maximum torque. For this reason, there are problems in that the DC motor 3 generates heat and the brushes deteriorate rapidly, and the connection between the DC motor 3 and the movable member 1, as well as the protrusion 1 of the movable member 1 and the stop lever 2, are subject to excessive pressure, which causes them to be removed. The problem with this method is that the accuracy deteriorates and eventually it becomes impossible to set an accurate initial position.

In view of the above-mentioned problems, the present invention provides a motor control system that allows an appropriate current to always flow through the DC motor in the forced stop state, prevents heat generation of the DC motor and deterioration of the brushes, and realizes highly reliable initial position setting operation. 〇 Means for solving the problem In order to solve the above problem, the motor control circuit of the present invention 11 A is provided.
-7 Both circuits have a gain switching terminal that switches the power gain in stages, are provided with a power supply circuit that supplies power to the DC motor, and are configured such that the control device supplies the control input of the gain switching terminal. It is something.

According to the present invention, with the above-described configuration, the control device switches the power gain of the power supply circuit to a low gain during the initial position setting operation and performs speed control, so that even if the DC motor is forced to stop, the DC motor remains Since the supplied current is limited, heat generation in the DC motor and deterioration of the brushes can be prevented. Furthermore, since the torque generated by the DC motor is also limited, the connecting portion between the DC motor and the movable member, the initial position detection member of the movable member, and the movable member stopping mechanism are not subjected to excessive pressure, so that the motor can be removed easily. There is no deterioration in accuracy during this process, and therefore a highly reliable initial position detection operation can be achieved at all times.

Embodiments Hereinafter, motor control circuits according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a motor control circuit in one embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example shown in FIG. 6 are given the same numbers, and their explanation will be omitted. 5 is terminal C1 terminal d, terminal e, terminal amount.

It has a terminal q, inputs two position pulses applied to terminal C9 and terminal d, and outputs a rotation direction command to terminal e, a speed command which is a digital signal to terminal f, and a terminal quantity according to a preset control procedure. This is a control device that outputs a gain switching command. 1o is a power supply circuit, and power supply 1
2 and an amplifier 11, and the amplifier 11 is connected to a switch 8.
The speed deviation signal is input through the power supply 1, and the output is the power supply 1.
Connected to 2. Next, the circuit configuration of the amplifier 110 will be explained. 14 is an operational amplifier, its non-inverting input is grounded, and its inverting input is connected to switch 8 via resistor 16.
A resistor 1 is connected to the output of the operational amplifier 14 via a resistor 16.
7 and the above output via a switch 18, respectively. The switch 18 is opened and closed by the gain cutoff 13 applied to the terminal q.

controlled by switching commands.

The operation of the motor control circuit configured as above will be explained below. The operation of this example includes a normal operation consisting of a speed control state and a positioning control state, and an initial position setting operation that sets a reference position for the normal operation. In the normal operation, the control device 6 always keeps the switch 18 in the OFF state. Therefore, the operation is the same as that of the conventional example described above. The initial position setting operation will be explained below. Power supply circuit 1 in the following explanation
0 supplies the current to the DC motor 3 as 110. In the initial position setting operation, the control device 6 outputs the speed command in the input direction, the rotation direction command, and the gain switching command shown in FIG. In the amplifier 11, the switch 18 is turned on by the gain switching command, so that the voltage gain G1 becomes as follows, with the resistance values of the resistors 16, 16, and 17 being R16°R16 and R17, respectively. voltage gain 147 when switch 18 is off;
-Go is, so by turning on the switch 18, the voltage gain decreases at the ratio of R1□/(R16+R1□),
Therefore, the power gain of the power supply circuit 10 also decreases. Amplifier 11 when switch 18 is turned off as shown in C of FIG.
The characteristics of the above-mentioned speed deviation signal, which is an input, and the current 11° flowing through the DC motor 3 are shown, and D shows the above-mentioned characteristics when the switch 18 is turned on. The speed of the DC motor 3 is controlled in the input direction by the speed command and the rotation direction command, and drives the movable member 1. Eventually, the protrusion 1a of the movable member 1
hits the stop lever 2 as shown in FIG. 2, and the DC motor 3 is forced to stop. At this time, the operating point of the power supply circuit 10 has shifted from the point E in FIG. 3 to the F point due to the gain switching, so that the DC motor 3 has no power as shown in FIGS. Limited sufficiently small current IF
will flow. The control device 6 detects that the direct current motor 3 is in the forced stop state from the above two position pulses, moves the direct current motor 3 to a preset initial position, and performs the initial position setting operation. Completing is the same as in the above conventional example.

As described above, this embodiment includes a power supply circuit having a gain switching terminal that switches the power gain in stages,
In the initial position setting operation, the control device switches the power gain to a low gain, thereby reducing the current IF flowing through the DC motor in the forced stop state, thus preventing excessive heat generation in the DC motor and deterioration of the brushes. At the same time, the torque generated by the DC motor can be limited by the current IF, so that the DC motor, the movable member, the protrusion of the movable member, and the stop lever are not subjected to excessive pressure, and high mounting accuracy can be maintained. , it is possible to realize highly reliable initial position setting. Furthermore, the above current Iy
The O value can be set to any value by appropriately setting the value of the resistor 17 without affecting controllability and responsiveness in normal operation.

In this embodiment, the power supply circuit 1o has a configuration in which the power gain can be switched only when the speed deviation signal is input, but the power supply circuit 10 can switch the power gain not only when the speed deviation signal is input. It is also possible to adopt a configuration in which the power gain can be switched even when the output of No. 13 is input.

In addition, in this embodiment, the power supply circuit 1o has a configuration in which the power gain can be switched in two stages, but the power supply circuit 1o
o may have a configuration in which the power gain can be switched in multiple stages.

Further, in this embodiment, the control device 6 has a control procedure that always keeps the power gain of the power supply circuit 10 in a high gain state during normal operation, but the control device 6 maintains the above power gain even during normal operation. The control device may have a control procedure for switching between a high gain state and a low gain state as necessary.

Effects of the Invention As described above, the present invention provides a motor control circuit with a power supply device that can switch the power gain in stages.
In the initial position setting operation, it is possible to limit the current flowing to the DC motor 17A-sorter, prevent deterioration of the DC motor and the mechanism driven by the DC motor, and realize highly reliable initial position setting. Furthermore, since the above can be realized at low cost with an extremely simple configuration, it has great industrial effects.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a motor control circuit in an embodiment of the present invention, Fig. 2 is a positional relationship diagram of the movable member 1 and stop lever 2 in a forced stop state, and Fig. 3 is an input/output characteristic diagram of the power supply circuit. , Fig. 4 is a waveform diagram of the main part of the present embodiment, Fig. 5 is a block diagram of the conventional motor control circuit, Fig. 6 is a waveform diagram of the main part of the conventional example, and Fig. 7 is the input of the power supply circuit. It is an output characteristic diagram. 1...Movable member, 2...Stop lever,
3...DC motor, 4...Position detector, 6, 19...Control device, 6...Speed deviation signal generator, 7... ... Switch switching circuit, 10.20 ... Power supply circuit, 11.21.
... Amplifier, 12 ... Power supply, 13
・・・・・・Phase compensator. side

Claims (2)

[Claims] (1) A movable member having an initial position detection member, and a movable member stopping mechanism that forcibly blocks movement of the movable member in one direction by hitting the initial position detection member and defines a movable range of the movable member. , a DC motor that drives the movable member, and a position detection means that is directly or indirectly connected to the rotation shaft of the DC motor and generates a one-phase or two-phase periodic position signal as the DC motor rotates. , inputting the position signal, a speed command which is a digital signal representing the target rotation speed at which the DC motor should rotate, and a rotation direction command representing the direction in which the DC motor should rotate, and waveform-shaping the position signal. means for generating a position pulse which is a pulse signal, and generating a speed deviation signal having a polarity proportional to the difference between the actual rotation speed of the DC motor and a target speed indicated by the speed command and corresponding to the rotation direction command; , phase compensation means for performing phase compensation using the position signal as input;
It has an input terminal and a gain switching terminal, supplies power to the DC motor, controls the active power supplied to the DC motor according to the voltage applied to the input terminal, and has a gain switching signal applied to the gain switching terminal. a power supply device that switches stepwise the power gain characteristic that is the relationship between the voltage and the active power, and either or both of the speed deviation signal and the output signal of the phase compensation means, and a selection means for selecting between a speed control state and a positioning control state for the DC motor by supplying a signal to the input terminal of the power supply device; A motor control circuit comprising a control device that outputs the speed command, the rotation direction command, and the gain switching signal according to a control procedure. (2) The control device outputs a speed command and a rotation direction command for driving the movable member in a direction in which the movable member stopping mechanism prevents the movement of the movable member, and also switches the power gain of the power supply device to a low gain, and then Since the rise or fall of the pulse is not detected for a preset certain period of time, it is detected that the movement of the movable member is blocked by the movable member stop mechanism, and the DC motor is determined based on the state of the position pulse at that time. It is characterized by having a control procedure of detecting the current position, performing positioning control by rotating the DC motor to an initial position that is a preset reference position based on the current position, and switching the power gain to a high gain. A motor control circuit according to claim 1.