JPS61245062A - Motor revolution degree detecting device - Google Patents

Abstract

PURPOSE:To detect exactly the revolution degree of a motor without increasing excessively a noise component by providing a primary coil, a secondary coil and a rotational signal detecting circuit, etc. CONSTITUTION:One end of a secondary coil 32 is connected to a connecting point (c) between a primary coil 31 and a motor 20. Also, an electromagnetic detecting circuit 30 for detecting an AC component generated on a signal line 21 by following the revolution of the motor 20 is constituted with the coils 31, 32. In this state, when a DC voltage V0 is applied onto the signal line 21 and a signal line 21a becomes an earth potential, a DC current flows to the motor 20 through the coil 31 from the signal line and the motor 20 rotates and an AC signal is generated in the magnetic field winding of the motor 20. Also, an induction voltage generated by the variation of the AC current flowing to the coil 31 is transferred to the coil 32. As for this voltage, the voltage V0 is eliminated by a coupling use capacitor 40 and thereafter, a prescribed DC voltage is applied at a connecting point (e) and a noise component is eliminated by a filter circuit 50. Also, when the revolution speed of the motor becomes high, a frequency, a pulse width and the number of pulses become large, small and large respectively, and the revolution degree of the motor 20 can be detected.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a device for detecting the degree of rotation such as the rotational position, number of rotations, and rotational speed of a DC electric motor. This is suitable for detecting the rotational position of a DC electric motor.

(Conventional technique) Conventionally, as a device for detecting the rotation degree of a DC electric motor,
A primary winding is provided in the current-carrying circuit of the motor, a secondary winding is provided near the primary winding without contact with the primary winding,
2. Description of the Related Art A technique is known in which a change in voltage signal caused by an alternating current of a motor flowing through a primary winding is detected, and a degree of rotation of the motor is detected based on a voltage signal appearing at a secondary winding.

(Problem to be solved by the invention) However, with the above technical means, when the current value of the AC component accompanying the rotation of the DC motor is small, the voltage value of the voltage signal detected at the primary winding is also very small. Therefore, detection on the secondary coil side becomes difficult. Here, if you try to amplify the voltage waveform appearing on the secondary coil side by increasing the number of turns of the secondary coil, noise that occurs when AC components are generated,
For example, distortion components generated between the motor brush and the commutator also increase, making accurate detection difficult.

A technical problem to be solved by the present invention is to make it possible to accurately detect the rotation degree of a motor using an electromagnetic coupling even when the AC component generated as the DC electric motor rotates is minute.

(Means for Solving the Problems) In order to achieve the above-mentioned technical problem, the present invention provides a energizing circuit for a DC electric motor, which includes a primary coil connected in series to the DC electric motor, and a primary coil connected in series to the DC electric motor. , connected between the primary coil and the DC electric motor, and
A technical means is adopted that includes a secondary coil magnetically coupled to the secondary coil and a rotation signal detection circuit that outputs a pulse signal according to the frequency of the signal appearing at the other end of the secondary coil.

(Function) Therefore, the voltage signal appearing at the other end of the secondary coil is a voltage signal whose power source is an alternating current component generated by the rotation of the direct current electric motor, and an interaction between the primary coil and the secondary coil. Since the voltage signal is obtained by adding the voltage signal generated by induction, even if the voltage value of the AC component is minute, the voltage signal appearing at the other end of the secondary coil can be reduced without increasing the number of turns, that is, the noise component. It becomes possible to amplify without increasing the value extremely.

Note that the frequency of the signal appearing at the other end of the secondary coil changes depending on the rotation degree of the motor. For example, as the rotation speed of the motor increases, the frequency increases, and accordingly, the pulse period output from the rotation signal detection circuit becomes shorter, and the number of pulses output per unit time increases. Therefore,
By counting the number of pulses, the degree of rotation such as the rotation speed and rotation angle of the motor can be detected.

(Example) The present invention will be described in detail below based on an example shown in the drawings.

In FIG. 1, reference numeral 10 denotes a control circuit for the DC electric motor 20, which is configured to apply a DC voltage V0 to the motor 20 to drive the motor 20. The motor 20 in the embodiment is used, for example, as a motor for moving an electric mirror of an automobile to a desired position.

A primary coil 31 that detects an alternating current component generated as the motor 20 rotates is connected in the middle of a signal line 21 that transmits direct current from the control circuit 10 to the motor 20 .

That is, the motor 2o and the primary coil 31 are connected in series.

One end of the secondary coil 32 is connected to the connection point C between the primary coil 31 and the motor 20.
2 are electromagnetically coupled with a positive mutual inductance M so that when an alternating current flows through the primary coil 31, an alternating current signal is generated by electromagnetic induction. Further, the primary coil 31 and the secondary coil 32 constitute an electromagnetic detection circuit 30 that detects an alternating current component generated on the signal line 21 as the motor 2o rotates.

A capacitor 40 for cutting DC components is connected to the other end of the secondary coil 32, and the capacitor 4° is connected to a resistor 51.
52 and a capacitor 53. This filter circuit 50 includes a comparator circuit 7
A connection point e of a DC constant voltage circuit 65 is connected to one input terminal of the comparator 71 through a resistor 64. Further, a connection point d between the capacitor 4° and the filter circuit 50 is connected to a connection point e via a resistor 63. Note that the resistor 61 is connected to a DC constant power source (not shown), and from the connection point e, the resistor 61
The divided DC voltage is taken out at and 62. Also resistance 6
The resistance values of 3 and 64 are set to be the same, and the DC voltages of the comparator 71-input terminal and the 10-input terminal are set to be approximately the same.

The output pulse signal of the comparator circuit 70 is input to the control circuit through a signal line 71, and the control circuit 10 is configured to count the number of pulses and control the energization of the motor 20.

Next, we will discuss the operation of this embodiment having the above configuration in the second section.
This will be explained with reference to the figures.

When a DC voltage v0 is applied to the signal line 21 and the signal line 21a is at ground potential, the DC current flows from the signal line 21 to the motor 20 via the primary coil 31, causing the motor to rotate. As the motor 20 rotates, an alternating current signal is generated in the field winding of the motor 20. Therefore, at this time, connection point C
A signal VC as shown in FIG. 2(a) appears. Note that in the figure, vcl is noise generated between the brush of the motor 20 and the commutator. This voltage signal ve
represents the AC power supply voltage generated as the motor 20 rotates. Further, since the induced voltage generated by the change in the alternating current flowing through the primary coil 31 is transmitted to the secondary coil 32 by electromagnetic induction, the voltage due to this magnetic coupling is added to the signal vc described above in the signal line 41. The signal ■3° (Fig. 2(b)) appears. Voltage signal V3° is a coupling.

After the DC voltage v0 is removed by the programming capacitor 40, a predetermined DC voltage V is applied at the connection point e, the noise component V11 is removed by the waveform shaping filter 50, and the waveform is shaped as shown in FIG. C) Signal ■ as shown in
. is input to one input terminal of the comparator 71 of the comparison circuit 70. Signal V here.

is a waveform centered on the voltage V determined by the resistance ratio of the resistors 61 and 62 and the resistor 63 of the constant voltage circuit 60. This signal V. is compared with a constant voltage v1 by the comparator circuit 70, and the signal %I71 contains the voltage Td in FIG.
A rotation pulse signal v7° as shown in is output.

Here, there is a correlation between the rotation of the motor 20 and the number of pulses; for example, one rotation of the motor outputs six pulses. When the rotational speed of the motor changes, for example, when the rotational speed increases, the signals Vc, Vsz, and V in FIG.
s. The frequency of becomes larger (the period becomes shorter), thus the signal V,. The pulse width becomes shorter, and the number of pulses output per unit time increases. Therefore, when this number of pulses is counted by the control circuit 10, the degree of rotation of the motor 20, for example, the rotation position of the motor 20, that is, the position of the mirror can be detected. Since the supply of the DC voltage v0 is stopped, the motor 20, that is, the mirror can be stopped at a desired rotational position.

Here, if a voltage is applied to the motor 20 in the opposite direction to the above, the motor 20 rotates in the opposite direction, but the connection point C of the signal line 21
An alternating current voltage is extracted from the motor in the same manner as above, and the rotational position of the motor can be detected.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, but can be similarly implemented in power window control, power seat control, etc. of a vehicle.

(Effects of the Invention) As described above, according to the present invention, even when the voltage value of the AC component generated by the rotation of the DC electric motor is minute, the secondary coil etc. The voltage value of the signal generated on the end side can be amplified to a sufficiently detectable extent, and the degree of rotation of the DC electric motor can be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the device of the present invention, and FIG. 2 is a waveform diagram showing voltage signal waveforms at various parts in FIG. 10...Primary coil, 32...Secondary coil, 50...
...Filter circuit, 65... Constant voltage circuit, 70...
・Comparison circuit. Representative Patent Attorney Takashi Okabe Figure 1 1n Figure 2

Claims (2)

[Claims] (1) a primary coil provided in a current-carrying circuit of a DC electric motor and connected in series to the DC electric motor, one end of which is connected between the primary coil and the DC electric motor;
A motor comprising: a secondary coil magnetically coupled to the primary coil; and a rotation signal detection circuit that outputs a pulse signal according to the frequency of a signal appearing at the other end of the secondary coil. Rotation detection device. (2) The rotation signal detection circuit includes a waveform shaping circuit that shapes the waveform of the signal appearing at the other end of the secondary coil, and compares the waveform-shaped signal voltage with a predetermined reference voltage.
The motor rotation degree detection device according to claim 1, further comprising a comparison circuit that outputs a pulse signal.