JPH01269821A - Motor rotation control device - Google Patents

Abstract

PURPOSE:To embody the rotary speed control of a motor with a simple circuit, by entering an output voltage of an amplification circuit and a zero cross point of commercial power source into a charging voltage of a CR timer which starts charge at the time of starting and a comparison circuit and triggering the power control elements of a thyristor or the like from said output signals. CONSTITUTION:A rotary speed of a motor in current use is incorporated as a pulse signal by a rotary speed sensor. The rotary speed is converted into a voltage signal equivalent to the rotary speed by an F/V conversion circuit 3. The voltage is compared with a preset constant voltage value. The differential voltage is amplified by an amplification circuit 10. On the other hand, a CR timer circuit 5, which starts charge with a zero cross point of commercial power source at a starting point, generates charging voltage which is subject to change with time, responding to its phase within the half wave of the commercial power source. When the charging voltage and the output voltage of the amplification circuit are entered into a comparison circuit 15, the circuit outputs the voltage converted into lag time from the zero cross point from the voltage of the amplification circuit. Therefore, a thyristor TRIAC 18, which drives the motor is triggered from this signal, the rotary speed of the motor can be feedback controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotation speed control device for use in fan motors of combustion appliances and the like.

Conventional technology Figure 5 shows the control circuit of a conventional oil combustion machine.

Oil-burning machines use a fan motor (FM) to supply combustion air.
), an electromagnetic pump (VP) that supplies fuel, and an ignition device (IG) that operates when ignited, and these loads are connected to a commercial power source and turned ON10 F F by a relay controlled by a control circuit. is common.

Problems to be Solved by the Invention However, in recent years, even in the field of oil combustion, there has been a desire to control the amount of combustion by switching between strong and weak levels. It is desired to control the

In order to meet these demands, for the electromagnetic bonder VP, a method of bypassing a portion of the supplied fuel and switching the combustion amount, and for the fan motor FM, a method of motor tap switching and rotation speed control methods are being considered. However, all of them have issues in controlling while maintaining the balance between fuel and air amounts. In particular, there is a problem in that the amount of fluctuation in the amount of fuel and air differs in response to voltage fluctuations in the commercial power supply, causing imbalance in combustion.

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, it is an object of the present invention to provide a circuit that realizes motor rotation speed control with a simple circuit and can programmably set the degree of variation in motor rotation speed with respect to fluctuations in commercial power supply voltage. do.

Means for Solving the Problems In order to achieve the above object, the present invention provides a rotation speed sensor such as a photointerrupter that captures a pulse signal synchronized with the rotation speed of a motor, and a voltage level signal corresponding to the frequency of the pulse signal. 1, an amplifier circuit that amplifies the difference voltage between this voltage level signal and a predetermined voltage value, and the output voltage of this amplifier circuit is connected to one input, and the other input is connected to a commercial It is equipped with a comparator circuit connected to the charge voltage of a CR timer that starts charging at the zero-crossing point of the power supply, and its output signal triggers a power control element such as a thyristor to control the motor phase. It is something.

Operation With the above configuration, first, the current rotational speed of the motor is taken in as a pulse signal by the rotational speed sensor, and is converted into a voltage level signal corresponding to the rotational speed by the F/V conversion circuit. This voltage is then compared with a preset constant voltage value, and the difference voltage is amplified by an amplifier circuit. Therefore, the deviation from the target rotational speed is amplified to a voltage level and output. On the other hand, a CR timer circuit that starts charging starting from the zero-crossing point of the commercial power supply generates a charging pressure that changes over time according to the phase within a half-wave of the commercial power supply. When this charging voltage and the output voltage of the amplifier circuit are input to a comparator circuit, the voltage of the amplifier circuit is converted into the delay time from zero cross and becomes an output. That is, when the motor rotation speed is lower than the target rotation speed, an output signal with a short delay time is obtained, and conversely, when it is higher than the target rotation speed, an output signal with a long delay time is obtained. Therefore, if this signal is used to trigger the thyristor or triac that drives the motor, the rotation speed of the motor can be feedback-controlled. Here, if the amplification factor of the amplifier circuit is set high, even if the deviation of the motor rotational speed from the target rotational speed is small, a large change in the energization phase of the thyristor and the trybook occurs, and the deviation can be corrected.

On the other hand, when the amplification factor is made relatively small (1 to 10), the amount of feedback to the energization phase decreases, and as a result, the rotation speed is stabilized at a rotation speed that is slightly deviated from the target rotation speed. In other words, the degree of variation in the rotational speed due to variations in commercial power supply voltage, etc. can be programmably set by the amplification factor of the amplifier circuit.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows the motor rotation speed control circuit of this embodiment. Reference numeral 1 in the figure indicates a motor to be controlled, which in this embodiment is a fan motor for supplying combustion air to an oil combustion machine. Reference numeral 2 is a photointerrupter, in which a part of the fan of the fan motor 1 is cut and raised, and this cuts off the slit between the LED and the phototransistor of the photointerrupter 2, turning off the phototransistor, thereby changing the rotation speed. It is configured to generate a pulse signal according to the

On the other hand, 3 is a power transformer that converts commercial power into a low voltage, and this voltage is double-wave rectified by a bridge diode 4.

This signal is then input to the CR timer circuit 5, which starts charging at zero cross.

Further, the double-wave rectified signal is separated by a diode 6 and then smoothed by an electrolytic capacitor 7 to produce a DC power source. In this embodiment, this voltage was set to 12 VDC.

This DC power supply is further converted into a stabilized power supply of 8V by a protective resistor 8 and a Zener diode 9, and is supplied as a power supply to the rotation speed control circuit.

10 is an operational amplifier of the amplifier circuit, the output voltage of the F/V conversion circuit is connected to the non-inverting input, and the resistor 11.12 is connected to the inverting input.
A constant voltage obtained by dividing the voltage is input through a resistor 13, and a resistor 14 is further inserted between the output and the output. Moreover, this output is connected to the non-inverting input of the operational amplifier 15,
On the other hand, the output signal of the CR timer circuit 5 is input to the inverting input. A photocoupler LED 17m is connected to the output of the operational amplifier 15 via a transistor 16, and a phototransistor 17b that receives this is connected to the gate of the thyristor 18. The trigger current of this thyristor 18 is applied through a resistor 19. Furthermore, the anode of the thyristor 18 is connected to the bridge diode 2.
0 to the fan motor 1.

Next, the operation of this embodiment will be explained.

The pulse signal taken in by the photointerrupter 2 is converted into a voltage level signal by the F/V conversion circuit 3, and the relationship between the voltage and the motor rotation speed is shown in FIG. The voltage has a positive slope with respect to the rotational speed, and this characteristic changes if the resistor 3a, capacitor 3b, etc. in FIG. 1 are changed. In this example, the control target rotation speed is 2800 r.
pm, and constants were selected so that the output voltage would be 4v. Also, resistors 11, 12, and 13 are each set to 1
If 0 is Ω and 14 is 50 Ω, for operational amplifier 10,
The difference voltage between the voltage 4V set by this resistor 11 and 12 and the output voltage of the F/V conversion circuit 3 is amplified to the ratio (5 times) of the resistors 13 and 14 using 4V as the reference voltage and output. . Therefore, if the motor rotation speed is high/
If the voltage is lowered, the output voltage of the operational amplifier 10 will also be raised or lowered based on 4V.

On the other hand, the signal double-wave rectified by the bridge diode 4 turns off the transistor 5a at the zero cross point, turns the transistor 5b into 6N, and discharges the capacitor 5C to 6V. Thereafter, it is charged by the resistor 5d, and when the voltage exceeds the non-inverting input of the operational amplifier 15, the output becomes Lo, the transistor 16 becomes 0FFI, and the LED 17m turns off.

When the phototransistor 17b reaches (5FFL), a current flows from the resistor 19, which triggers the thyristor 18 to 6N, and the fan motor 1 is energized.

FIG. 3 shows the voltage waveforms of each circuit. @ is the relationship between the output voltage of the F/V conversion circuit 3 and the motor rotation speed, ■ is the relationship between the output voltage of the operational amplifier 10 of the amplifier circuit and the motor rotation speed, and is amplified five times compared to the deviation from 4V. has been done. ◎ is the charging voltage waveform of the CR timer, and C is discharged every time the commercial power supply zero crosses. FIG. 6(a) shows how the phase control angle to the fan motor 1 when the reference rotation speed is 2800 rpm is determined by these curves. Similarly, (b) of the same figure shows the phase control angle when the rotational speed is slightly lowered (270 rpm). As can be seen from the figure, in this case, the conduction angle is wider than in (a), and it can be seen that the control is working in the direction of correcting the drop in the motor rotation speed.

Next, consider fluctuations in the motor rotation speed with respect to voltage fluctuations in the commercial power supply. Naturally, if the voltage drops, the motor rotation speed will temporarily drop, and then the feedback control mentioned above will try to increase the rotation speed, but it will not return to the standard rotation speed and will remain at a lower rotation position than that. Stabilize. The stable motor rotation speed is determined by the amount of feedback, that is, the amplification factor of the amplifier circuit. The same applies when the commercial power supply voltage increases.

FIG. 4 shows the results of measuring the relationship between the commercial power supply voltage vA0 and the motor rotation speed by varying the amplification factor G of the amplifier circuit. As can be seen from this result, the commercial power supply voltage characteristic of the motor rotation speed can be easily changed by simply changing the amplification factor determined by the value of the resistors 13 and 14.

Further, in this embodiment, the reference rotation speed is set to 2800 rpm, but if it is desired to change this value, this can be easily done by changing the constants of the resistor 13a and the capacitor 13b.

Effect of the invention As is clear from the above description of the embodiments, according to the present invention, (1) Motor rotation speed control can be realized with a simple circuit.

(2) Furthermore, the dependence of the rotation speed control on the commercial power supply voltage can be easily and programmably variably set.

It is particularly effective in applications that require munching with electromagnetic pumps for fuel supply, such as fan motors for supplying combustion air in combustion equipment, and increases the amount of combustion.・Weak control can be easily achieved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a motor rotation speed control device according to an embodiment of the present invention, Fig. 2 is a characteristic curve diagram of the motor rotation speed and F/V conversion circuit, and Fig. 3 is a waveform diagram of each part of the circuit. FIG. 4 is a commercial power supply voltage dependence curve of the motor rotation speed, and FIG. 5 is a circuit diagram of a conventional control device for an oil-burning machine. 1...(fan) motor, 2...photo interrupter (rotation speed sensor), 3...F/
V conversion circuit, 5... CR meta 4 circuit (zero cross start), 10... operational amplifier (amplification circuit), 15... operational amplifier (comparison circuit), 18.
...Thyristor (power control element). Name of agent: Patent attorney Toshio Nakao and 1 other person32
Figure morph plane rotation general (rPm) Figure 3 (+2) FM army Guntotsutsu Figure 4 □ VAC (v) Figure 5

Claims (1)

[Claims] A rotation speed sensor that captures a pulse signal synchronized with the rotation speed of the motor, an F/V conversion circuit that converts the pulse signal into a voltage level signal according to the frequency, and a difference between this voltage level signal and a predetermined voltage value. an amplifier circuit that amplifies the voltage;
The output voltage of this amplifier circuit is connected to one input, and the other input is connected to the charging voltage of a CR timer that starts charging from the zero cross point of the commercial power supply. A motor rotation speed control device configured to apply a trigger to a control element and perform phase control of the motor.