JPS6158499A - Position and speed detector of stepping motor - Google Patents

Abstract

PURPOSE:To obtain a rotary position and a rotary speed signal of a rotor without special sensor by detecting the induced voltage of an exciting coil at different rotary positions. CONSTITUTION:Induced voltages Ea1, Eb1 are respectively output in phase difference pi/2 from exciting coils 1, 2, 3, 4 of unexcited state. Then, the induced voltages Ea1, Eb1 are input through differential amplifiers 7a, 7b and the first waveform shapers 8a, 8b to a calculator 9. The signal is calculated by the calculator 9 to become a position signal Pa=sinNtheta and a position signal Pb= cosNtheta, and presented at output terminals 18a, 18b. Thus, a speed signal V and position signals Pa, Pb are simultaneously obtained from induced voltages Ea1, Eb1.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an electrical device for detecting the rotational position and rotational speed of a stepping motor.

Prior Art For example, in a servo control system for position control, the first
The configuration is as shown in the figure. That is, the target value S is applied to the adjustment section 41 via the summing point 40, and is applied as an operation signal to the motor 42 serving as the operation section. Here, the motor 42 drives a controlled object 43 that is affected by external disturbances. On the other hand, the detection unit 44 detects the control target 43
Detects the control amount of and uses the above addition point 40 as the measured value.
is fed back to the adjustment section 41 as a deviation. In such a servo control system, an encoder, a potentiometer, a resolver, etc. are used as a position sensor of the detection unit 44, and a tachogenerator is used as a speed detection sensor.

Therefore, such a conventional servo system for position control requires special sensors and also requires coupling these sensors to a motor or load, but this coupling process creates a dead zone or a dead zone in the servo system. Hysteresis characteristics occur and control characteristics deteriorate.

OBJECTS OF THE INVENTION AND SOLUTIONS THEREOF Therefore, an object of the present invention is to determine the rotational position of the rotor and the feedback signal of the servo system from the induced voltage generated in the magnetic pole coils of the motor, etc., without using a special sensor as in the past. The purpose is to obtain a rotation speed signal.

Therefore, the present invention detects the induced voltage of the excitation coil of a stepping motor at different rotational positions, detects it as a voltage with a phase difference of π/2, that is, the induced voltage in the form of sine and cosine, and squares these induced voltages. , addition,
By performing operations such as square root and waveform shaping, the speed signal (dθ/dt) and position signal (s i nNθ
, cosNθ) are obtained at the same time.

Configuration of the Invention Below, the configuration of the present invention will be specifically explained based on FIGS. 2 to 4.

First, FIG. 2 shows a position and speed detection device 1 of the present invention. The excitation coils (1), (2), (2), (2) of the stepping motor 2 to be detected are connected to a drive circuit 4 in the induced voltage detection means 3.

This drive circuit 4 and the distribution circuit 5 connected to its input end are both connected to a switching circuit 6 on the output side. This switching circuit 6 has two output ends connected to one input end of each differential amplifier 7a, 7b. The other input terminal of the differential amplifiers 7a and 7b is
It is connected to a common power supply terminal 33, and is also commonly connected to the connection point of the excitation coils (1) and (2) and the connection point of the excitation coils (2) and (2).

The output terminals of the differential amplifiers 7a and 7b are connected to one input terminal of the square circuits 10a and 10b and the division circuits 15a and 15b inside the arithmetic circuit 9 through the first waveform shaping circuits 8a and 8b, respectively. has been done. These square circuits 10a and 10b are both an adder circuit 11 and a parallel root circuit 1.
2. It is sequentially connected to the output terminal 17 of the speed signal V via the second waveform shaping circuit 13 and the amplifier circuit 14.

Further, the output terminal of the second waveform shaping circuit 13 is also connected to the other input terminals of the division circuits 15a and 15b.

These division circuits 15a and 15b are each an amplifier circuit 16a.
, 16b and the position signal pa.

pb output terminals 18a and 18b, respectively.

Next, FIG. 3 shows a specific circuit example of the induced voltage detection means 3 using the two-phase excitation method. Control signals φf and φ2 are input from input terminals 19.20 and applied directly or via inverters 21.22 to the bases of switching transistors 23.24.25.26, respectively. The transistors 23, 24, 25, and 26 are connected between the respective terminals of the excitation coils (1), (2), (2), (3) and the ground 27. In addition, the switching elements 28, 29, 30, and 31 of the switching circuit 6 include the excitation coil ■,
■, ■, one end of ■, and the respective differential amplifiers 7a, 7b
is connected to the input end of the These switch elements 28, 29, 30, 31 receive the control signals φ1,
It is designed to be driven directly by φ2 or by a signal inverted by impark 21, 22, respectively.

Operation of the Invention Next, the operation of the position and speed detection device 1 will be explained.

Since the control signals φ1 and φ2 shown in FIG. 4 are input to the input terminals 19.20 of the drive circuit 4 with different phases, the switching transistors 23.24.2
5.26 repeats on and off sequentially. As a result, the excitation coils ■, ■, ■, ■ have the phases shown in Figure 4.
Excitation current I flows sequentially. As a result, the rotor 2a of the stepping motor 2 rotates in synchronization with the control signals φ1 and φ2.

On the other hand, the control signals φ1, φ2 are applied to the switching elements 28, 29, 30, . . . directly or by the inverters 21, 22.
31, the switching elements 28, 29, 30, 31 are sequentially turned on corresponding to the excitation coils 2, 2, 3, and 3 in the non-excited state. That is, for example, at time t, the excitation coils ■, ■
is in the excited state, the switch elements 29 and 31 corresponding to the other excitation coils ① and ② are in the on state.

In this way, the excitation coil in the de-energized state ■, ■, ■,
The induced voltages Eal and Ea2 are extracted from (2) with a phase difference of π/2. The switch element 28.29 or the switch element 30.31 is alternately turned on and off, but its two-phase output, that is, the induced voltages Eal and Eb2 are in a continuous state on the time axis.

These induced voltages Eal and Ebl are applied to the respective differential amplifiers 7a and 7b and the first waveform shaping circuits 8a and 8b.
The signal is input to the arithmetic circuit 9 via the .

Here, the first waveform shaping circuits 8a and 8b generate an induced voltage E
In addition to removing harmonics of al and Ebl, excitation coils ■, ■,
The voltage components induced by the self-inductances (1) and (2) and their mutual inductance are removed. As a result, the outputs of the first waveform shaping circuits 8a and 8b, that is, the induced voltages Eat and Ebl, are determined as follows when the number of poles is N, the maximum value is A, and the rotation angle is θ. The value is proportional to the product of the magnetic position, the magnetization distribution (sinNθ), and the rotational speed (dθ/dt) of the rotor 2a.

Ea 1wAs inNθ−dθ/dtEbl=Aco
sNθ・dθ/dt Next, the induced voltages Eal and Ebl are squared through square circuits 10a and 10b, respectively, and squared signals Ea2 and E
b2 and both are input to the adder circuit 11. here(
The following signal E3 is obtained as the output of the adder circuit 11 by using the theorem of trigonometric functions: sin2θ+cosθ=1].

E3= (AsinNθ?+(ACO,SNθde=(A
−dθ/dt)” Then, this signal E3 is converted into a signal E by the square root circuit 12.
4=lA-dθ/dtl, and the second waveform shaping circuit 1
3 inputs. Here, the second waveform shaping circuit 13 has a function of converting dθ/dt into a required positive/negative signal because the signal is processed in absolute value by using the square root circuit 12 at the previous stage. In this way, the signal E5=A-dθ/dt as the output of the second waveform shaping circuit 13 passes through the amplifier circuit 14 and becomes the speed signal ■.

On the other hand, this signal E5 is divided by the voltages Eal and Ebl by the division circuits 15a and 15b, and the signal Ea6 is
-sinNθ or after the signal Eb6=cosNθ, it is amplified by the respective amplifier circuits 16a and 16b,
Position signal Pa-5inNθ and position signal Pb=cos
Nθ and appears at the output terminals 18a and 18b. In this way, the speed signal (2) and the position signals Pa, Pb are obtained simultaneously from the induced voltages Eal and Ebl.

Structure and operation of other embodiments Next, FIG. 4 shows a bipolar stepping motor 1.
Excitation coils ■, ■ and separate search coils 32a, 32b
An example is shown in which .

These search coils 32a and 32b are arranged with a phase difference of π/2, and generate induced voltages Eat and Ebl when the rotor 2a rotates as described above.

The subsequent operation is similar to that of the embodiment shown in FIG.

Modifications of the Invention In the above embodiment, the arithmetic circuit 9 is realized by a plurality of necessary functional circuits, but such operations and functions can also be realized in the field of computer programs.
In this case, the computing section of the computer is equivalent to the computing circuit 9 described above.

Effect of the invention The present invention provides the following unique effects.

First, position signals and speed signals of a controlled object can be detected without using sensors such as encoders, potentiometers, and resolvers. This is not only advantageous in terms of cost, but also increases the degree of freedom in terms of space, and has the functional effect of reducing unnecessary suspension bands, hysteresis characteristics, etc. in the servo system.

Next, a position signal and a speed signal can be obtained at the same time with a simple circuit configuration. In other words, in the case of a unipolar stepping motor, it is sufficient to add an arithmetic circuit.
Furthermore, in the case of a bipolar stepping motor, the purpose can be easily achieved by adding a search coil, an arithmetic circuit, and the like.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a general servo system, Fig. 2 is a block diagram of a stepping motor position and speed detection device of the present invention, Fig. 3 is a circuit diagram of a drive circuit and a switching circuit, and Fig. 4 5 is a time chart showing control signals, excitation states and switching states, and FIG. 5 is a block diagram of another embodiment. 1. Stepping motor position and speed detection device ff
i, 2...Stepping motor, 2a...Rotor, 3...
- Induced voltage detection means, 4... Drive circuit, 5... Distribution circuit, 6... Switching circuit, 7a, 7b... Differential amplifier, 8a, 8b... First waveform shaping circuit, 9--/JI arithmetic circuit, ioa, 10b...square circuit, 11...addition circuit, 12...square root circuit, 13...second waveform shaping circuit,
14...Amplification circuit, 15a, 15b...Division circuit, 1
6a, 16b...Amplification circuit, 17.18a, 18b...
Output terminal.

Claims (1)

[Claims] a rotor, an induced voltage generating means that generates an induced voltage by the rotation of the rotor, a first waveform shaping circuit that divides the induced voltage generated by the induced voltage generating means into sine and cosine shapes and shapes the waveform; and a square circuit that squares each signal output from the first waveform shaping circuit in the form of a cosine, an adder circuit that adds the signals from the square circuit, and a square root circuit that takes the route of the signal from the adder circuit. a second waveform shaping circuit that converts the signal from this square root circuit into a required positive/negative signal; and a division that divides each signal from the first waveform shaping circuit by the signal from this second waveform shaping circuit. A stepper motor position and speed detection circuit, characterized in that the signal from the second waveform shaping circuit is detected as a rotor speed signal, and each signal from the division circuit is detected as a rotor position signal. Device.