JPH0530780A - Motor controlling circuit and motor controller - Google Patents

Abstract

PURPOSE:To provide a motor controlling circuit and motor controller, which can conduct a stable constant drive even in the case of using detecting elements being unstable because of uneven characteristics. CONSTITUTION:An input amplification circuit 13 is provided with AGC circuit 14a, the AGC circuit 14a monitors an amplified signal B to generate a gain signal Ga, and a differential amplifier 13a changes the amplification factor of its own according to the gain signal Ga so that the amplified signal B having an appropriate amplitude is generated always.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control circuit and a motor control device, and more particularly to a motor control circuit such as a fan motor and a motor control device including the motor control circuit.

[0002]

2. Description of the Related Art FIG. 3 is a diagram of a control circuit for a single-phase motor as an example of the configuration of a conventional motor control device. This motor control device includes a motor 1, a sense circuit 2, an input amplifier circuit 3, and a power drive circuit 4. Motor 1
Has a single coil because it is a single-phase motor, and rotates when a drive current is passed through this coil 1a.
The sense circuit 2 is mainly composed of a Hall element 2a as a detection element, senses the rotation phase of the motor 1,
The detection signal A is output as a potential difference. The Hall element 2a is placed in an active state by the current flowing from the power supply Vcc to the ground GND via the resistors 2b and 2c. The input amplifier circuit 3 is mainly composed of two differential amplifiers 3a and 3b, and a detection signal A is amplified by the differential amplifiers 3a and 3b, and two amplified signals B whose phases are mutually inverted. , * B are generated and sent to the power drive circuit 4.

The electric power driving circuit 4 is composed of two electric power amplifying circuits 4a and 4b having bidirectional driving capability of sending and inflowing, and receives the amplified signals B and * B, and their phases are mutually inverted. Generate currents of two drive voltages C and * C,
A current according to the potential difference between these drive voltages C and * C is applied to both ends of the coil 1a. In short, a current according to the drive voltages C and * C is generated from the detection signal A of the rotation phase of the motor 1,
This alternating current is passed to drive the motor 1 in single-phase full-wave mode. In this way, the motor 1, the sense circuit 2, the input amplifier circuit 3, and the power drive circuit 4 form a feedback loop,
Since the motor 1 is driven by the current according to the drive voltages C and * C corresponding to the rotation state of the motor 1, the motor 1 operates at a constant rotation speed in the steady state.

[0004]

As described above, in the conventional motor control circuit, the sense circuit 2 is configured by using the Hall element, the photo sensor, or the like as the detection element. Then, since the currents of the drive voltages C and * C are generated based on the detection signal A from the detection element, the characteristics of the detection element directly affect the performance of the motor 1. This situation will be specifically described with reference to the waveform diagram of FIG. 2. First, when the output level of the detection signal A is proper, the amplified signals B and * B are not distorted, and the drive voltages C and * C are effective. The entire range of the power supply voltage Vcc and the ground voltage GND is sufficiently swung while maintaining the waveform (waveform in which the top is slightly collapsed) (see FIG. 2A).

Next, when the output level of the detection signal A is lower than the proper state, the waveforms of the amplified signals B and * B are not distorted but their amplitudes are small, so that the drive voltages C and * C keep their waveforms. Cannot maintain sufficient amplitude (Fig. 2
(See (b)). In this case, there are inconveniences that the driving capability is insufficient and the rotation speed of the motor is reduced, and that the power amplifier circuits 4a and 4b consume extra power and generate more heat to shorten the life of the transistor. Further, when the output level of the detection signal A is higher than the proper state, the amplitudes of the amplified signals B and * B are also large, and the drive voltages C and * C cannot hold a valid waveform and the power supply voltage Vcc and the ground voltage GND are not maintained. And the top of the waveform is severely collapsed (see FIG. 2 (c)). In this case, undesired noise is generated along with the disturbance of the waveform.

There are two characteristics of the detecting element which cause such an influence, that is, the variation of the generated signal level among the elements and the temperature characteristic of the single element. For example, in the case of a Hall element, the maximum value of the detection signal A is about 70 mV at room temperature, but the value of the detection signal A often reaches 30 mV when the temperature changes by 50 ° C. Conventionally, as a measure regarding this,
Selection of detection elements and circuit adjustment are performed. In order to suppress the variation among the elements, elements having a constant generated signal level are selected, and only elements having good temperature characteristics (small temperature coefficient) are selected. Then, after the device is assembled, the generated signal level is adjusted by the resistors 2b, 2c and the like in order to eliminate the influence due to the variation of each element.

However, such conventional measures require a great deal of labor for selection and adjustment. In addition, the yield of element selection directly becomes a cost factor, the secular change in the element characteristics causes the performance deterioration of the apparatus, and further, the rotational operation of the apparatus is not stable until the detection element reaches a thermal equilibrium state. There are conventional devices. The purpose of this invention is
The present invention is intended to solve such a problem of the conventional technology, and realizes a motor control circuit that performs stable and constant driving even when an unstable detection element having uneven characteristics is used. It provides a motor controller with high performance and long life.

[0008]

An improvement of the motor control device of the present invention for achieving this object is that an AGC circuit is provided in the input amplification circuit of the motor control circuit and that the amplification factor of the differential amplifier is increased. I made it variable. In the configuration of this input amplifier circuit, the differential amplifier inputs the detection signal from the detection element, amplifies the detection signal, and generates an amplified signal. Here, the AGC circuit is specifically composed of, for example, a rectifier circuit and a low-pass filter, the amplified signal is input, a local average value of the amplitude of this signal is obtained, and a gain corresponding to this value is obtained. Generate a signal. The differential amplifier receives the gain signal and changes its amplification factor according to the value thereof.

That is, when the value of the gain signal indicates that the amplitude of the amplified signal is larger than a predetermined value, the amplification factor is decreased, and the amplitude of the amplified signal is smaller than the predetermined value. At times, the amplification factor is increased so that the amplitude of the amplified signal is always kept at a predetermined value. The components other than the input amplifier circuit, specifically, the motor, the sense circuit, the power drive circuit and the like may be conventional ones.

[0010]

In the motor control device of the present invention having the motor control circuit having the above-described structure, the AGC is stable even if the output level of the detection signal fluctuates as long as the phase and waveform of the detection signal are stable. By the function of the circuit and the differential amplifier following this, an amplified signal having an appropriate waveform and amplitude is output from the input amplifier circuit. Therefore, the motor control circuit can operate stably because it is not affected by the fluctuation of the output level of the detection signal, and the transistor of the power amplifier circuit is not overloaded.

Since the automatic gain control by the AGC circuit is always performed dynamically, it not only removes the influence due to the characteristic variation among the detecting elements, but also eliminates the influence due to the temperature characteristic and aging. . As a result, the step of selecting the detection elements becomes almost unnecessary, and the yield of the detection elements is not affected. Further, the adjustment work by the resistance or the like is easy because the accuracy may be rough, and the readjustment is not required even after many years, so the maintainability is improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of a motor control device of the present invention, which is a control circuit for a single-phase motor, and corresponds to FIG. 3 of a conventional example. The input amplifier circuit 13 is improved, and the motor 1, the sense circuit 2, and the power drive circuit 4 are the same as those of the conventional one. Further, in order to avoid making the drawings complicated, the differential amplifiers 13a and 13b and the power amplifier circuits 4a and 4b are represented by the same simplified symbols as in the conventional example.

The input amplifier circuit 13 includes an AGC circuit 14a,
14b is newly provided, the differential amplifier 13a changes its amplification factor according to the gain signal Ga from the AGC circuit 14a, and the differential amplifier 13b changes its amplification factor according to the gain signal Gb from the AGC circuit 14b. The differential amplifier 13a and the AGC circuit 14a and the differential amplifier 13b and the AGC circuit 14b have the same structure, and two amplified signals B whose phases are inverted from the detection signal A,
* B is generated.

At this time, the AGC circuit Ga generates a gain signal Ga from the amplified signal B, and the gain signal Ga 13 is generated.
Since the differential amplifier 13a changes its amplification factor according to a, the amplitude of the amplified signal B is always held at an appropriate value. The same applies to the amplified signal * B, except that the phase is inverted. This is shown in FIG.
Specifically, referring to the waveform diagram of FIG. 1, first, when the output level of the detection signal A is proper, the signal A and the signal Ga are shown by solid lines in the figure. The signal Ga is generated and the amplified signal B is not distorted. Therefore, the driving voltage C is sufficiently oscillated over the entire range of the power supply voltage Vcc and the ground voltage GND while maintaining an effective waveform.

Next, in the case where the output level of the detection signal A is too low in the conventional case, the signal A and the signal Ga are shown by broken lines in the figure, but the amplification factor in the differential amplifier 13a is shown. A large value of the gain signal Ga is generated in order to raise the voltage, and the amplified signal B keeps the waveform of the proper amplitude. Therefore, the drive voltage C also keeps the effective waveform and the power supply voltage Vcc.
And the entire range of the ground voltage GND can be sufficiently swung. further,
When the output level of the detection signal A is considered to be too high in the conventional case, the signal A and the signal Ga are shown by the dashed line in the figure, but they are small values in order to reduce the amplification factor of the differential amplifier 13a. Of the gain signal Ga is generated, the amplified signal B keeps the waveform of the proper amplitude, and therefore the drive voltage C
Power supply voltage Vcc and ground voltage GN while maintaining an effective waveform
The full range with D can be swung sufficiently.

Thus, even if the characteristics of the output level of the Hall element 2a are uneven or unstable, the appropriate drive voltages C and * C are applied to both ends of the coil 1a, so that the motor 1 is It will always maintain a stable rotation state. Therefore, it is possible to realize a motor control circuit that performs stable and constant drive regardless of the characteristics of the hall element 2a. The Hall element 2a of this embodiment is a specific example of the detecting element, and the same effect can be obtained even if the detecting element is, for example, a photo sensor.

[0017]

As described above, according to the present invention, it is possible to realize a motor control circuit which performs stable and constant driving even if a detection element having an uneven characteristic and an unstable detection element is used. There is an effect that it is possible to provide a motor control device which has a long performance and is easy to maintain due to its performance.

[Brief description of drawings]

FIG. 1 is a diagram of a control circuit of a single-phase motor, which is an embodiment of a motor control device of the present invention.

2 (a), (b) and (c) are waveform diagrams of respective signals in a conventional motor control circuit. (D) is a waveform diagram of each signal in the motor control circuit of the present invention.

FIG. 3 shows an example of a configuration of a conventional motor control device,
It is a figure of the control circuit of a single phase motor.

[Explanation of symbols]

1 motor 1a coil 2 sense circuit 2a Hall element 3 input amplifier circuit 3a, 3b differential amplifier 4 power drive circuit 4a, 4b power amplifier circuit 13 Input amplifier circuit 13a, 13b Differential amplifier 14a, 14b AGC circuit

Claims (2)

[Claims] 1. A motor control circuit for generating a current having a drive voltage based on a detection signal of a rotation phase of a motor, wherein an AGC circuit is provided in an input amplification circuit for amplifying the detection signal by a differential amplifier, and the AGC circuit is provided. Receives a signal amplified by the differential amplifier and generates a gain signal according to the amplitude of the signal, and the differential amplifier receives the gain signal and changes the amplification factor in accordance with the gain signal. A motor control circuit which outputs a signal amplified to the amplitude of. 2. A motor control device for generating a current having a drive voltage based on a detection signal of a rotation phase of a motor, wherein an AGC circuit is provided in an input amplification circuit for amplifying the detection signal by a differential amplifier, and the AGC circuit is provided. Receives a signal amplified by the differential amplifier and generates a gain signal according to the amplitude of the signal, and the differential amplifier receives the gain signal and changes the amplification factor in accordance with the gain signal. A motor control device, which outputs a signal amplified to the amplitude of.