JPS61154496A - Rotating speed controller - Google Patents

Abstract

PURPOSE:To obtain the linearity of control even in a low speed rotating range by controlling ON or OFF in the low speed rotating range, and controlling the ON/OFF control period proportionally to the temperature of an object to be cooled. CONSTITUTION:When a fan motor 8 is disposed in a stable high speed rotating range control, a Zener diode 10 is OFF. Thus, a thyristor 7 is controlled in phase in response to a temperature detection signal A. Since the diode 10 is turned ON in the low speed range, a current is flowed to a resistor 9 to generate a potential difference across the resistor 9. Thus, an error voltage V1 is generated in a differential amplifier 5. A comparator 13 compares the voltage V1 with a triangular wave signal V2, and generates a pulse (e). A conduction angle signal C fed from the comparator 5 is supplied to a trigger pulse generator 5 during a period that an AND gate 14 is gated by the pulse (e), and the thyristor 7 is controlled ON or OFF at the prescribed period during the output of the signal (e).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation speed control device for a fan motor whose phase angle is controlled.

[Conventional technology]

FIG. 4 shows a conventional rotation speed control device for a condenser fan motor. In the figure, 1 is a thermistor installed in the pipe of the condenser, 2 is a temperature detection circuit, and the thermistor t
A voltage signal (hereinafter referred to as a temperature detection signal) A that is inversely proportional to the condensing temperature T of the condenser is generated. 3
is a synchronous circuit. This synchronization circuit 3 generates a triangular wave signal B synchronized with a half cycle of the voltage of the AC power supply 4. 5 is a comparison circuit which compares the temperature detection signal A and the triangular wave signal B, and outputs a conduction angle signal (phase control signal) while A>B.
Generate C. Reference numeral 6 denotes a trigger circuit which receives the conduction angle signal C, generates a trigger pulse in synchronization with the conduction angle signal C, and supplies it to the gate of the thyritus 7. This thyristor 7 is connected in series with the fan motor 8 and controls the phase of the input voltage to the fan motor supplied with power from the AC power source 4.

FIG. 5(a) shows the relationship between the condensing temperature T and the temperature detection signal A, and FIG. shows the relationship between the condensing temperature T and the rotation speed n of the fan motor.

In the above configuration, when the rotation speed n of the fan motor 8 decreases, the condensation temperature T of the condenser increases, and when the rotation speed n increases, the condensation temperature T decreases, but the level of the temperature detection signal A When the value increases, it decreases, and when it decreases, it increases.

For example, when the condensing temperature T decreases and the level of the temperature detection signal A increases, the conduction angle signal C becomes narrower, the generation phase of the trigger pulse P is delayed, and the power supply voltage to the fan motor 8 decreases. The rotation speed n decreases. This rotation speed n
The condensing temperature T begins to rise due to the decrease in the rotation speed n.
increases, and the condensing temperature T decreases, but eventually stabilizes at a certain rotation speed n that is in equilibrium with the condensing temperature T.

[Problem that the invention seeks to solve]

In this way, in a fan motor whose negative voltage is controlled by phase angle, the torque drop in the low-speed rotation range is large, so linearity of control cannot be obtained in the low-speed rotation range. There is a hysteresis between the fan motor and the rotation speed as shown in Figure 6, and the control of the fan motor lacks stability in the low speed rotation range, so there is a problem that the desired control characteristics regarding the condensing temperature cannot be obtained. Ta.

This invention was made to solve the above problem.
It is an object of the present invention to obtain a fan motor rotation speed control device that can linearly control the rotation speed of a fan motor over the entire speed range in accordance with the temperature of the object to be cooled, and that can improve the temperature control characteristics. purpose.

[Means to solve the problem]

In order to achieve the above object, this invention has the following advantages:
The firing phase of the thyristor is fixed, and the period during which the firing phase is fixed is controlled in accordance with the level of the temperature detection signal.

[Effect]

In this invention, in the low speed rotation range, the thyristor is controlled to be on/off at a constant cycle, and the period of on/off control, that is, the number of times it is turned on, is increased or decreased in accordance with the temperature, so that there is a difference between the temperature and the rotation speed. Linearity is ensured.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a temperature detection signal A is inputted to the inverting input side of a comparator circuit 5 via a resistor 9 and a Zener diode (Zener potential z) lO. , 11 is a differential amplifier circuit which receives the voltage across the resistor 9 and outputs an error voltage v1. Reference numeral 12 denotes a triangular wave generating circuit which generates a triangular wave signal (2) having a period t1 sufficiently longer than the period of the wave number of the power supply section of the AC power source 4.

13 is a comparator circuit, which compares the error voltage ■1 and the triangular wave signal.
(2) Compared with 2, pulse e is generated while V2>Vl. 14 is an AND circuit which receives the outputs of the comparison circuits 5 and 13 and sends an output to the trigger pulse generation circuit 6 when both outputs are at H level.

Note that the Zener potential Vz corresponds to the voltage level of the temperature detection signal A corresponding to the rotation speed ng near the hysteresis region shown in FIG. 6 in the rotation speed characteristics of the fan motor 8.

In this configuration, when the condensing temperature T is higher than a certain temperature TO and the level of the temperature detection signal A is lower than the Zener potential Vz, that is, when the fan motor 8 is in a stable high speed rotation range, Temperature detection signal A is the comparator circuit 5
The conduction angle signal C is compared with the triangular wave j word B and input to the AND circuit 14. At this time, since the Zener diode 10 is off, no current flows through the resistor 9, and the voltage across the resistor 9 is zero volts, so Vl<V2, and the output of the comparison circuit 13 is at H level. Therefore, the AND circuit 14 is gated, and the conduction angle signal C is directly input to the trigger pulse generation circuit 6 through the AND circuit 14, so that the firing phase of the thyristor 7 is set at the level of the temperature detection signal A, as in the conventional case. The rotation speed n of the fan motor 8 increases or decreases in proportion to the increase or decrease in the condensing temperature T.

Conversely, when the condensation temperature T falls below a certain temperature TO and the level of the temperature detection signal A becomes higher than the Zener potential Vz, the Zener diode 10 is turned on, so a current flows through the resistor 9, creating a potential difference across the resistor 9. occurs. Therefore, an error voltage (1) is generated, and a pulse signal e as shown in FIG. 3 is generated. On the other hand, the level of the temperature detection signal A reaching the inverting input of the comparator circuit 5 is as shown in FIG.
z, the conduction angle signal C sent out by the comparator circuit 5 becomes a pulse with a constant period and a predetermined width, and the pulse C
As shown in FIG. 3, during the period when the AND circuit 14 is gated by the pulse signal e, is supplied to the trigger pulse generation circuit 6 through the AND circuit 14, and is applied to the thyristor 7.
is controlled to be turned on and off at regular intervals while the pulse signal e is being output. During the pulse of this pulse signal e, t2
is proportional to the increase/decrease of the condensing temperature T (temperature detection signal A
(according to the decrease/increase of), the fan motor 8
The average input voltage of the fan motor 8 is proportional to the condensing temperature T.
The rotation speed n increases or decreases linearly in proportion to the condensing temperature T.

Therefore, the hysteresis phenomenon described above in FIG. 6 is substantially eliminated, and the control characteristics in the low speed rotation range are improved.

〔Effect of the invention〕

As explained above, this invention has a configuration in which the firing phase of the thyristor is fixed in the low speed rotation region of the fan motor to perform on/off control, and the on/off control period is controlled in proportion to the temperature of the object to be cooled. As a result, linearity of control can be ensured even in the low speed rotation range, and hysteresis phenomenon can be virtually eliminated and stable control can be achieved over the entire speed range, improving the temperature control characteristics of the object to be cooled. I can't do anything.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a diagram for explaining the action of the Zener diode in the above embodiment, Fig. 3 is a waveform diagram of each part in the above embodiment, and Fig. 4 is a block diagram of a conventional rotation speed control device, No. 5
Figure (a) is a diagram showing the relationship between condensing temperature and temperature detection signal, and Figure 5 (b)
1 is a waveform diagram of each part in the conventional example, and FIG. 6 is a temperature-rotational speed characteristic diagram in the conventional example. In the figure, 2 - temperature detection circuit, 3 - synchronization circuit, 5 comparison circuit, 6 - flame pulse generation circuit, 7 - thyristor, 8 - fan motor, 9 - resistor, 10 - Zener diode, 11 - Differential amplifier circuit, 12-.-triangular wave generation circuit, 13-.-comparison circuit, 14-.-AND circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a device that controls the rotational speed of the fan motor by controlling the phase angle of the input voltage of the fan motor using a thyristor in accordance with the temperature of the object to be cooled, the firing phase of the thyristor is controlled in a low rotational speed range below a predetermined rotational speed. A rotation speed control device characterized in that the thyritus is controlled on and off while being fixed, and the period during which the on and off control is performed is increased or decreased in proportion to the temperature.