JPH0219720B2 - - Google Patents

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, a servo control system for position control generally has a configuration as shown in FIG. 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 as the operation section. Here motor 42
drives the controlled object 43 that is affected by the disturbance D. On the other hand, the detection section 44 detects the control amount of the controlled object 43 and feeds it back to the addition point 40 as a measurement value, thereby providing the control amount to the adjustment section 41 as a deviation. In such a servo control system, an encoder, potentiometer, resolver, etc. are used as a position sensor of the detection unit 44,
Additionally, a tachogenerator is used as a sensor for speed detection.

Therefore, such a conventional servo system for position control requires special sensors, and it is also necessary to couple these sensors to a motor or load, but this coupling process requires that the servo system Dead zones and hysteresis characteristics occur, deteriorating control characteristics.

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

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, an induced voltage in the form of sine and cosine, and By performing operations such as squaring, addition, square root, and waveform shaping, speed signals (dθ/dt) and position signals (sinNθ, cosNθ) are obtained simultaneously.

Configuration of the Invention Hereinafter, 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 coil of the stepping motor 2 to be detected is connected to a drive circuit 4 within the induced voltage detection means 3. This drive circuit 4 and the distribution circuit 5 connected to its input side are both connected to a switching circuit 6 on their output side. This switching circuit 6
are the respective differential amplifiers 7a,
7b. The other input terminals of the differential amplifiers 7a and 7b are connected to a common power supply terminal 33, and are also connected to the connection point of the excitation coil and the connection point of the excitation coil.

The output terminals of the differential amplifiers 7a and 7b are
They are connected to one input end of square circuits 10a, 10b and division circuits 15a, 15b inside arithmetic circuit 9 through first waveform shaping circuits 8a, 8b, respectively. These square circuits 10a, 10b
are sequentially connected to the output terminal 17 of the speed signal V via the adder circuit 11, the parallel root circuit 12, the second waveform shaping circuit 13, and the amplifier circuit 14.

Further, the output terminal of the second waveform shaping circuit 13 is connected to the other input terminals of the division circuits 15a and 15b. These division circuits 15a and 15b receive position signals via amplifier circuits 16a and 16b, respectively.
They are connected to output terminals 18a and 18b of Pa and Pb, respectively.

Next, FIG. 3 shows a specific circuit example of the induced voltage detection means 3 using the two-phase excitation method. Control signals φ1 and φ2 are input from input terminals 19 and 20, and are directly or via inverters 21 and 22.
Switching transistors 23, 24, 25,
26 bases, respectively. The transistors 23, 24, 25, and 26 are connected between respective terminals of the excitation coils and ground 27. Further, the switching elements 28, 29, 30, and 31 of the switching circuit 6 are connected to one end of the excitation coil and the input end of each of the differential amplifiers 7a and 7b. And these switch elements 28, 29,
30 and 31 are driven directly by the control devices φ1 and φ2 or by signals inverted by the inverters 21 and 22, respectively.

Effects of the Invention Next, the effects 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 and 20 of the drive circuit 4 while having different phases, the switching transistors 23, 24, 25, and 26 are turned on and off in sequence. Repeat off. As a result, the excitation coil,
, magnetic currents sequentially flow in phases as shown in FIG. 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 and φ2 are applied to the switch elements 2 directly or by inverters 21 and 22.
8, 29, 30, 31, so those switch elements 28, 29, 3
0 and 31 are excitation coils in a non-excited state,
, and are sequentially turned on.
That is, for example, at time t, the excitation coil is in the excited state, so the other excitation coils,
The corresponding switch elements 29 and 31 are turned on. In this way, the induced voltages Ea1 and Ea2 are extracted from the excitation coils in the non-excited state with a phase difference of π/2. Switch elements 28, 29 or switch elements 30, 31
repeats on and off alternately, but its two-phase output, that is, the induced voltages Ea1 and Eb2, on the time axis,
It is in a continuous state.

The induced voltages Ea1 and Eb2 are input to the arithmetic circuit 9 through the respective differential amplifiers 7a and 7b and first waveform shaping circuits 8a and 8b. Here, the first waveform shaping circuits 8a and 8b remove harmonics of the induced voltages Ea1 and Eb2, as well as voltage components induced by the self-inductance of the excitation coils and their mutual inductance. There is. As a result, the outputs of the first waveform shaping circuits 8a and 8b, that is, the induced voltages Ea1 and Eb2
If the number of poles is N, the maximum value is A, and the rotation angle is θ, then the magnetization position and magnetization distribution (sinNθ) of the rotor 2a and the rotation speed (dθ/dt) of the rotor 2a are as follows. The product is a proportional value.

Ea1=AsinNθ・dθ/dt Eb1=AcosNθ・dθ/dt Next, the induced voltages Ea1 and Eb1 are squared through square circuits 10a and 10b, respectively, and become square signals Ea2 and Eb2, which are both input to the adder circuit 11. Ru. Here, using the trigonometric function theorem [sin ² θ+cos ² θ=1], the following signal E3 is obtained as the output of the adder circuit 11.

E3=(AsinNθ・dθ/dt) ² +(AcosNθ・dθ/dt) ² =A・dθ/dt) ^2Then , this signal E3 is converted into signal E4=|A・dθ/dt| by the square root circuit 12. , serves as an input to the second waveform shaping circuit 13. Here, the second waveform shaping circuit 13 has a function of converting dθ/dt into a positive or negative signal depending on the direction of rotation, since the signal is processed as an absolute value by using the square root circuit 12 in the previous stage.
In this way, the signal E5=A·dθ/dt as the output of the second waveform shaping circuit 13 becomes the speed signal V through the amplifier circuit 14.

On the other hand, this signal E5 is
By dividing the above voltages Ea1 and Eb1 by,
After the signal Ea6=sinNθ or the signal Eb6=cosNθ, it is amplified by the respective amplifier circuits 16a and 16b, and the position signal Pa=sinNθ and the position signal
Pb=cosNθ, which appears at the output terminals 18a and 18b. In this way, the speed signal V and the position signals Pa, Pb are obtained simultaneously from the induced voltages Ea1, Eb1.

Structure and operation of other embodiments Next, FIG. 4 shows an example in which an excitation coil and search coils 32a and 32b are separately added to the bipolar stepping motor 1.
These search coils 32a, 32b are π/2
When the rotor 2a rotates, the induced voltages Ea1, Ea1,
Generate Eb1. The subsequent operation is similar to that of the embodiment shown in FIG.

Modification of the Invention In the above embodiment, the arithmetic circuit 9 is realized by a plurality of necessary functional circuits, but since such arithmetic function can also be realized in the field of computer programming, the computer program in that case is The arithmetic unit is equivalent to the arithmetic circuit 9 described above.

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

First, the position and velocity signals of the 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 dead zones, hysteresis characteristics, etc. in the servo system.

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

[Brief explanation of drawings]

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 is a block diagram of a stepping motor position and speed detection device of the present invention. The figure is a time chart showing control signals, excitation states and switching states, and FIG. 5 is a block diagram of another embodiment. DESCRIPTION OF SYMBOLS 1...Stepping motor position and speed detection device, 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... arithmetic circuit, 10a, 10
b...square circuit, 11...addition circuit, 12...square root circuit, 13...second waveform shaping circuit, 14...
...Amplification circuit, 15a, 15b...Divider circuit, 16
a, 16b...Amplification circuit, 17, 18a, 18b
...Output terminal.

Claims (1)

[Claims] 1 A rotor, a plurality of coils facing the rotor and excited at different phases, and a plurality of switching transistors provided corresponding to each coil of the plurality of coils are sequentially turned on to sequentially excite each of the above-mentioned coils. and a switching circuit that has a plurality of switch elements provided corresponding to each of the coils and turns on the switch element corresponding to a non-excited coil among the plurality of coils. an induced voltage generating means for detecting an induced voltage generated in a non-excited coil due to rotation of the rotor; a first waveform shaping circuit for dividing the induced voltage into sine and cosine shapes and shaping 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 the square root circuit into positive and negative signals; and a division circuit that divides each signal from the first waveform shaping circuit by the signal from the second waveform shaping circuit. has
A stepping motor position and speed detection device 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.