JPH02106199A - Method and circuit for controlling closed loop of stepping motor - Google Patents

Abstract

PURPOSE:To energize a motor at an optimum timing by setting a current command and a leading angle independently to optimum values in response to a motor speed and a rotating state. CONSTITUTION:The difference between a rotor position signal from an encoder E coupled to the rotary shaft of a stepping motor SM and a set position signal is obtained by a counter CUT, and its output is converted to an analog signal by a converter D/A. The rotor position signal from the encoder is converted to a rotor speed signal by a frequency/voltage converter F/V. An exciting current is determined by a first amplifier Al on the basis of the output of the converters D/A and F/V to be supplied. The address of the ROM storage circuit of an exciting sequence determining circuit SQ is composed of a signal corresponding to a rotor position signal, a rotor rotating direction, a rotating direction command signal. a speed difference polarity signal, a rotor rotating speed signal, and a rotation/stop signal to generate an exciting sequence signal corresponding to the winding and its polarity to be excited.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a closed loop control method and circuit for a stepping motor.

In particular, the present invention relates to a closed-loop control method and apparatus for a stepping motor that uses both a current command signal based on a deviation between a command speed and an actual speed, and a lead angle signal that determines an excitation state based on a speed signal and a rotation command direction signal.

The lead angle herein means the amount of deviation angle between the stable position of the rotor in the magnetic field created by the stator and the current position of the rotor, expressed in units of rotor steps.

b. Conventional Technology Methods and circuits for controlling a stepping motor using a current command signal based on the deviation between the commanded speed and the actual speed are known.

C0 Problems to be Solved by the Invention In conventional closed-loop control methods and circuits for stepping motors, the rise of the excitation field is delayed due to coil inductance and induced voltage, making it difficult to achieve appropriate excitation timing. As a result, a decrease in torque constant and efficiency, an increase in temperature rise, and a deterioration in speed controllability were caused.

d. Means for Solving the Problem The above problem consists of an encoder that is coupled to the shaft of a stepping motor and generates a rotor position signal corresponding to the rotor position, and a rotor rotation speed detection circuit that detects the rotor rotation speed from the rotor position signal. a rotor rotation direction detection circuit that detects the rotation direction of the rotor from a rotor position signal, a rotation direction command signal generation circuit that generates a rotation direction command signal based on the deviation between the set position signal and the rotor position signal, and a set rotation speed. A speed difference winding signal generation circuit that generates a speed difference polarity signal corresponding to the difference in rotor rotation speed, a rotation/stop signal generation circuit that commands rotation/stop of the stepping motor, a rotation direction command signal and a rotor rotation speed signal. a first amplifier circuit that determines and supplies an excitation current based on the rotor position signal, the rotor rotation direction, the rotation direction command signal, the speed difference polarity signal, the rotor rotation speed signal, and the rotation/stop signal. An excitation sequencer circuit that determines the stator coil to be excited based on the lead angle; and a current determined by the first amplification is applied to the stator coil by intermittent operation of the excitation circuit of the stator coil based on a control signal from the excitation sequencer circuit. The present invention has been solved by a method and circuit for closed-loop control of a stepping motor, characterized in that it comprises a second amplifier circuit that supplies

e. Effect FIG. 3 is an example of a diagram for determining the lead angle.

The rotation direction command signal is shown on the horizontal axis, with rightward direction indicating clockwise direction and leftward direction indicating counterclockwise direction. The motor speed signal ■ is shown on the vertical axis, with upward direction indicating clockwise direction and downward direction indicating counterclockwise direction.

The inner region of radius V indicates a low velocity region, and the outer region indicates a high velocity region. The horizontal axis of the first and third quadrants and the straight line C0N
5T T: The sandwiched area indicates the acceleration area AC, and the straight line C
The area above 0N5T indicates a constant speed area, and the area between the straight line C0N5T and the vertical axis indicates a deceleration area DC. Furthermore, the second and third quadrants indicate that the motor speed signal (2) and the rotational direction command signal (2) are in opposite directions and are in the braking range BR.

A lead angle is predetermined for each region. For example, in the high speed acceleration range, it is 4.25 (STEP), and in the low speed acceleration range, it is 3.25 (STEP).

Note that the lead angle can be determined by adding other factors such as a stop command signal in addition to factors such as the motor speed and one rotation direction command to control the motor more precisely.

FIG. 4 is a diagram showing an example of a table for determining the stator coil to be excited based on the rotor position and lead angle. There are 20 stators, and the current rotor position is between the 199th and 0th stators. When the lead angle (LA) determined according to Fig. 3 is 4,25 (STEP), the excitation state (EX'CITING 5TATE)
becomes Seed 8 (line 4, column 1). Current rotor position is 1
When it is between the stator and the second stator, the excitation state is N.

9 (4th line, 2nd column).

FIG. 5 shows the excitation state of each winding (A, B, C, D, E) when the excitation state (ES) is determined.

No current flows in the A winding when the excitation state (ES) is Nα2 and Nα12, current flows in the positive direction between Na13 and Nα0, and flows in the opposite direction between Nα3 and Nα11. Similarly, for B winding, C winding, D winding, and E winding, ES is Nα
4 and NO, 14, N (L6 and N (116, NO, 8 and N
o, 18, No, l When O and 0, no current flows, respectively, between Nα5 and Nα13, between Na17 and Nα5, between NO19 and No, ]7, No, I
and Nα9, the current flows in the positive direction, and k
Between 15 and N03, No. 7 and Nα15, No. 1
When between 9 and Nα7, No, 11 and No, l9, current flows in the opposite direction.

In this way, the excitation state of each S line is determined.

Current is supplied to each winding from a first amplifier circuit which determines the excitation current using known methods on the basis of the set angular position, rotor position and rotor speed signals.

f. Embodiment FIG. 1 is a block diagram of the main parts of a circuit for implementing the closed-loop control method for a stepping motor according to the present invention.

An encoder E is connected to the rotating shaft of the stepping motor SM, and the difference between the rotor position signal and the set position signal from the encoder E is determined by a counting circuit CNT, and the output of the counting circuit CNT is converted into an analog signal by a digital/analog conversion circuit D/A. is converted to

The rotor position signal from the encoder is converted into a rotor speed signal using the frequency/voltage conversion circuit F/V. The amplifier circuit AI determines and supplies the excitation current.

The excitation sequence determining circuit SO includes a ROM storage circuit,
The address of the 110M memory circuit consists of a digital signal that is a combination of digital signals corresponding to a rotor position signal, a rotor rotation direction 2 rotation direction command signal, a speed difference polarity signal, and a rotor rotation speed signal 1 rotation/stop normal signal, as shown in FIG. Figures 4 and 5
According to the conditions corresponding to the table shown in the figure, an excitation t-sequence signal is generated which corresponds to the winding to be energized and its polarity.

The second amplifier circuit A2 has a circuit configuration as shown in FIG. 2, for example.

The second amplifier circuit includes a switch 01. Mouth 2. Equipped with QIO, each switch 01. Mouth 2. -QIO is excitation sequence determination circuit SQ
It is controlled by a signal from ti to excite a predetermined winding.

The current supplied to the winding is changed by changing the duty ratio of the current from the electric current tXps using a duty ratio changing switch 00 according to a signal from the first amplifier circuit AI provided via the waveform conversion circuit WT. controlled.

g. Effects of the invention The current command and lead angle can be independently set to optimum values according to the motor speed and rotational state.

Therefore, the influence of the inductance and induced voltage of the motor coil can be suppressed, and excitation can be performed at optimal timing. As a result, it is possible to realize a closed loop control method for a stepping motor with good controllability and high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a circuit for realizing the closed-loop control method for a stepping motor according to the present invention, FIG. 2 is a circuit diagram of the second amplifier circuit and its surrounding parts, and FIG. is a diagram for determining the lead angle, Figure 4 is a diagram showing an example of a table for determining the stator coil to be excited from the rotor position and lead angle, and Figure 5 is the excitation of each winding when the excitation state is determined. It is a figure showing a state. A--first amplifier circuit, A2-- second amplifier circuit,
CIIT...Counting circuit, To/0/...Digital/analog conversion circuit, E...Encoder, F/V...Frequency/voltage conversion circuit QO...Duty ratio change switch/7chi Ql- QIO
...Swifter, SH...Stepping motor, SO...Excitation sequence determination circuit. Figure 3■ Figure 4

Claims (2)

[Claims] (1) A first amplifier circuit that determines and supplies an excitation current based on a rotational direction command signal and a rotor rotational speed signal, a rotor position signal, a rotor rotational direction, a rotational direction command signal, a speed difference polarity signal, and a rotor rotational speed signal. and an excitation sequencer circuit that determines the lead angle based on the rotation/stop signal and determines the stator coil to be excited based on the lead angle; 1. A closed-loop control method for a stepping motor, characterized by using a second amplification circuit that supplies a current set by the first amplification to a stator coil. (2) an encoder coupled to the shaft of the stepping motor and generating a rotor position signal corresponding to the rotor position;
A rotor rotation speed detection circuit that detects the rotor rotation speed from the rotor position signal, a rotor rotation direction detection circuit that detects the rotor rotation direction from the rotor position signal, and a rotation direction command signal based on the deviation between the set position signal and the rotor position signal. a rotational direction command signal generation circuit that generates a rotational direction command signal generation circuit, a speed difference polarity signal generation circuit that generates a speed difference polarity signal corresponding to the difference between the set rotational speed and the rotor rotational speed, and a rotation/stop signal generation circuit that generates a speed difference polarity signal that corresponds to the difference between the set rotational speed and the rotor rotational speed. a signal generation circuit, a first amplifier circuit that determines and supplies an excitation current based on a rotational direction command signal and a rotor rotational speed signal, a rotor position signal, a rotor rotational direction, a rotational direction command signal, a speed difference polarity signal, and a rotor rotation. An excitation sequencer circuit that determines a lead angle based on a speed signal and a rotation/stop signal and determines a stator coil to be excited based on the lead angle, and an excitation circuit for the stator coils that is switched on and off based on a control signal from the excitation sequencer circuit. A closed-loop control circuit for a stepping motor, comprising a second amplification circuit that supplies a current set by the first amplification to a stator coil.