JPH01152996A - Analog wave type chasing type stepping motor driving system - Google Patents

Abstract

PURPOSE: To make the circuit scale small and make the circuit inexpensive and simplify the synchronization by making a step motor coil current follow sine waves and cosine waves. CONSTITUTION: A triangular wave generating circuit 11 generates triangular waves synchronized with clock, and a sine/cosine converting circuit 12 converts this wave into sine wave and cosine wave. An analog system of chopper control circuit 13 modulates the width of the sine wave and cosine wave with the detection voltage of a current sense resistor, and also makes the half wave rectified output of the sine wave slid 180 deg. in phase from one another and the cosine wave slid 180 deg. in phase from one another from the width modulated output. Hereby, the step motor coil current is made to follow the analog waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an analog waveform tracking type step motor drive system that can be used in all fields that use step motors.

[Conventional technology]

BACKGROUND ART Conventionally, drive systems for step motors include a one-phase system, a two-phase system, and a one- to two-phase system that is a combination of a Japanese system and a two-phase system. These drive methods generate ringing because they are driven by square wave signals.
There is a problem in that the vibration noise during driving is large. For this reason,
Conventionally, a microstep method has been used, which produces low vibration noise when driven (particularly at low speeds).

FIG. 5 is a block diagram showing the conventional microstep method, and FIG. 6 is a waveform diagram. In the figure, 1 is a counter group, 2 is a ROM for sine wave generation, 3 is a ROM for COS wave generation, and 4
．． 5 is a D/A converter, 6 is a half-wave rectifier and chopper control circuit, 7 is a motor drive circuit, 8 is a step motor, R□
, RsZ are sense resistors.

In the figure, counter group l is for creating an address signal to ROM2.3, and R0M2.3 is for D
This data table is prepared as a data table for outputting a sine wave and a CO3 wave to the /A converter 4.5.

The D/A converter 4.5 is for generating a heliance voltage in the control circuit 6. In response to this, the control circuit 6 compares it with the voltage value detected by the current sense resistor R A drive signal output to the step motor 8 is created by pulse width modulation so that the current flowing through the resistors R0, R, and □ becomes constant.

Next, the operation will be explained. The counter group 1 receives a clock input and generates an address signal. According to the address signal from this counter group 1, the sine wave generation ROM 2, c
The sine wave and CO3 wave data are read from the OS wave generation ROM 3, and the D/A converter 4.5 outputs the data as shown in Fig. 6 (b).
, is converted into an analog signal as shown in (c). This analog signal is a stepped sine wave and a CO3 wave that change stepwise in synchronization with the clock shown in FIG. 6(a). These signals are applied to the half-wave rectifier and chopper control circuit 6, and are shown in FIGS.
Signals with a phase shift of 90" as shown in FIG. The signal from Ro is fed back to configure a servo drive system, and stable drive is performed.

Such a microstep system is characterized in that there are as many stable stopping positions of the rotor as there are microsteps, and there are few vibration components, especially at low speeds.

[Problems to be solved by the invention]

However, the conventional microstep drive method
A high-speed clock corresponding to the waveform approximation steps is required for in-wave and cos-wave generation, and the approximation accuracy is determined by the number of steps.
Since a D/A converter, a rectifier, etc. are required, the circuit scale becomes large and expensive, and a step motor step clock is also required, which has drawbacks such as difficulty in synchronizing the steps.

The present invention is intended to solve the above problems; it does not require a step clock, the approximation accuracy does not depend on the number of steps, and it does not require RAM, ROM, D/A converter, rectifier, etc. An object of the present invention is to provide an analog waveform tracking type step motor drive system that can reduce the circuit scale and cost.

[Means for solving problems]

To this end, the analog waveform tracking step motor drive system of the present invention includes a triangular wave generation circuit that generates a triangular wave in synchronization with a clock, a waveform conversion circuit that converts the triangular wave into a sine wave and a cosine wave, and a sine wave and a cosine wave output. and a step motor drive circuit controlled by the chopper control circuit. An analog switch allows the width modulated outputs to be 180” out of phase with each other.
It is characterized by creating a half-wave rectified output of an in wave and a cos wave whose phase is shifted by 180 degrees from each other.

(Function) The present invention generates a triangular wave using a triangular wave generating circuit, converts the triangular wave into a sine wave and a cosine wave, and converts the triangular wave into a sine wave and a cosine wave using the detection voltage of the current sense resistor of the step motor drive circuit in the analog chopper control circuit. 180” out of phase with each other from the width modulated output.
The step motor coil current is made to follow the analog waveform by creating a half-wave rectified output of n waves and cos waves whose phases are shifted by 180° from each other.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of the analog waveform tracking type step motor drive system according to the present invention, in which 11 is a triangular wave generation circuit, 12 is a sine wave and CO3 wave conversion circuit, and 13 is a triangular wave generation circuit.
14 is a drive circuit, and 15 is a step motor.

In the figure, a triangular wave is generated in a triangular wave generation circuit 11 in synchronization with a synchronization signal, and the waveform is converted into a sine wave and a cosine wave in a sine wave and cosine wave conversion circuit 12. The chopper control circuit 13 generates a sine wave, C
The O3 wave is compared with the voltage detected by the current sense resistors R□ and Ro, the width of the sine wave and the CO3 wave are modulated, and the driving circuit 14 is controlled to be driven by the sine wave and the cosine wave for a period greater than the detected voltage. This chopper control circuit 13 and drive circuit 1
4 constitutes a servo drive system. In this way, the step motor is driven by the drive circuit 14.

Next, the analog waveform tracking type step motor drive system of the present invention will be explained in more detail based on an embodiment with reference to FIGS. 2, 3, and 4.

Figure 2 is a diagram showing a triangular wave generation circuit, sine wave, and cosine wave generation circuit, Figure 3 is a diagram showing a chopper control circuit, drive circuit, and step motor, and Figure 4 is a waveform diagram.
1 is an analog switch, 22 is an integral triangular wave generation circuit,
23 is an analog switch, 24 is an amplifier, 25 is an inverting amplifier, 26 is a non-inverting amplifier, 27.28 is a waveform conversion circuit, 29 is an amplifier, 30 is an analog switch, 31.32
is a comparator, 33.34 is a voltage follower, 35
．． 36 is an analog switch, 37 is a drive circuit, 38.3
9 is a step motor drive coil, 40.41 is a protection diode, and 42.43 is a smoothing circuit.

In the figure, the triangular wave generating circuit 22 is composed of an integrator. The switch 23 is configured to change the amplification degree of the amplifier 24 by switching and selecting the resistance value, and to change the rising and falling slopes of the triangular wave to select the frequency of the triangular wave. The inverting amplifier 25 and the non-inverting amplifier 26 are used to obtain triangular wave outputs of opposite phase and in-phase.

The waveform conversion circuits 27 and 28 consist of a combination of an operational amplifier and a Zener diode, and include Zener diodes D+ and D.
Current-voltage characteristic of z V0=-kT/q(nnls-5nl
Using e), approximate the turning part of the triangular wave to the square power, and s
Generates in waves and cos waves. analog switch 30
is the comparator 31.32 for sine wave and COS wave output.
This is for switching and connecting as a heliference voltage. Comparators 31 and 32 compare the reference voltage with detection voltages from current sense resistors R□, R, and ffi applied via voltage followers for impedance conversion, and send width-modulated outputs to switches 35 and 36. It is for the purpose of Switch 35.36 has 9
The A clock and B clock with a 0" phase shift are added to each, and by fixing it to the ground level for half a cycle, a sine wave (physiological phase, A phase) with a 180" phase shift from each other,
each other.

This is for applying a half-wave rectified output of a cosine wave (B phase, B phase) whose phase is shifted by 180'' to the drive circuit 37. Motor coil 38.3 with half-wave rectified sine wave and cos wave output
Drive 9. The diodes 40 and 41 are for absorbing back electromotive force generated in the coil.

Next, the operation will be described. As shown in FIG. 4(a), in synchronization with the lock input, the analog switch 21 creates and outputs a rectangular wave that changes in positive and negative directions.

The integral type triangular wave generation circuit 22 integrates this rectangular wave power,
A triangular wave as shown in FIG. 4 (b) is generated. This triangular wave is passed through an amplifier 24 to an inverting amplifier and a non-inverting amplifier 25.
．． In addition to 26, triangular waves of opposite phase and in-phase are generated. In the waveform conversion circuits 27 and 28, the folded portion of the triangular wave is approximated to the square of the square characteristic of the diodes Dr and Dt, respectively, and full-wave rectification of the sine wave and the cosine wave is performed as shown in Fig. 4 (c) and (d). Generate output. This full wave rectified output is applied to comparators 31, 32 via analog switches. A chopper clock is applied to the comparator via the amplifier 29, and at this timing, the full-wave rectified output is compared with the detection voltages of the current sense resistors R11 and R12, and the width-modulated sine wave and Cog wave full-wave rectified output are generated. is sent to switch circuits 35 and 36.

In the switch circuits 35 and 36, in synchronization with the A clock and the B clock, which are out of phase with each other by 906, the signals shown in FIG. 4 (E) and (
Half-wave rectified output A phase as shown in (f), (g), (g),
A-phase, B-phase, and B-phase outputs are generated, and the drive circuit 37 receives these signals and supplies current to the coils 38 and 39. Therefore, the motor coil current follows the waveforms of sine waves and cosine waves.

〔Effect of the invention〕

As described above, according to the present invention, there is no need for step crosses and there is no number of steps because it is an analog method, so it can be said that the approximation accuracy is infinite when compared to the microstep method.

In addition, since RAM, ROM, D/A converter, rectifier, etc. are not required, the circuit size can be reduced, which makes the circuit less expensive. Furthermore, there is no need for a clock higher than the step motor step clock. It becomes extremely easy to synchronize.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an analog waveform tracking type step motor drive system according to the present invention, and FIG. 2 is a diagram showing a triangular wave generation circuit and sine wave and cosine wave generation circuits.
FIG. 3 is a diagram showing a chopper control circuit, drive circuit, and step motor, FIG. 4 is a waveform diagram, FIG. 5 is a block diagram showing a conventional microstep method, and FIG. 6 is a waveform diagram. 11...triangular wave generation circuit, 12...sin wave, CO
3-wave conversion circuit, 13...Chopper control circuit, 14...
- Drive circuit, 15... Step motor, 21... Analog switch, 22... Integral triangular wave generation circuit, 2
3...Analog switch, 24...Amplifier, 25.
...Inverting amplifier, 26...Non-inverting amplifier, 27.28
...Waveform conversion circuit, 29...Amplifier, 30...Analog switch, 31.32...Comparator, 33
．． 34... Voltage follower, 35.36... Switch, 37... Drive circuit, 38.39... Stub motor drive coil, 40.41... Protection diode, 42.43... Smoothing circuit. Applicant Xerox Corporation Agent
Patent Attorney Hirukawa Masanobu (2 others) Figure 1 Figure 4 (+) 2] Σ-111/ζ- Figure 5 Figure 6 (A) 7σ・7□

Claims (1)

[Claims] Controlled by a triangular wave generation circuit that generates a triangular wave in synchronization with a clock, a waveform conversion circuit that converts the triangular wave into a sine wave and a cosine wave, a chopper control circuit to which sine wave and cosine wave outputs are added, and a chopper control circuit. and a step motor drive circuit, and the chopper control circuit is a sin
The width of the wave and the cosine wave are modulated by the detection voltage of the current sense resistor of the motor drive circuit, and an analog switch generates a sine wave with a phase shift of 180 degrees from the width modulation output, and a half cosine wave with a phase shift of 180 degrees with each other. An analog waveform tracking type step motor drive system that creates a wave rectified output.