KR850000323B1 - Control circuit for refrigerator - Google Patents

Abstract

A refrigerator has a compressor with the compressor rotation controlled by a digital-controlled frequency inverter. Because the difference bands between the real room temperature and setting value of the refrigerator are divided into plural numbers, the rotation of the compressor is controlled by the digital signal based on the load through the frequency inverter.

Description

Refrigeration capacity automatic adjustment refrigerator corresponding to load

1 is a circuit diagram of the present invention,

2 is a graph showing a state in which the temperature fluctuation range is divided into a plurality of zones in the present invention.

3 and 4 are graphs showing relatively high loads and small loads in relation to temperature and frequency.

* Explanation of symbols for main parts of the drawings

Block A ': Frequency converter A: Frequency conversion control circuit

B: rectifier circuit C: control unit

D: defrost

The present invention is to control the compressor of the refrigerator, by dividing the bee temperature and set temperature value into a plurality of zones so that the rotation speed of the compressor is automatically converted according to each zone to cope with the load that can maintain the constant high temperature always It relates to a freezing capacity automatic adjustment refrigerator circuit.

Conventional refrigerator circuits have a constant refrigeration capacity by a compressor operating at a constant rotational speed after setting a high temperature by installing an electronic F-dimmer using a freon gas injection type thermo-stat and a temperature sensor. The compressor stops when the preset lower limit temperature is reached, and when the Gone temperature rises to the set upper limit temperature, the compressor is restarted and the compressor repeats the ON-OFF operation. Refers to the amount of heat taken in unit time in order to maintain the required temperature of the freezer and freezer compartment.) Because the compressor is kept at the required temperature, the freezing capacity of the compressor is constant. So that when you store a lot of food, If the stored food is small, when the load is small, the high temperature is lower than the set temperature. At this time, the compressor is rotated at a higher speed than necessary, causing unnecessary power loss.

Therefore, rapid freezing is impossible, and there is a limit in food storage capacity, and due to the frequent ON-OFF operation, the compressor consumes a lot of power due to the overcurrent required at every start-up. Many defects are inherent, such as the problem of relay life.

The present invention uses a digitally controlled frequency converter as a control device for eliminating these shortcomings and converting the rotational speed of the low compressor, and dividing the difference between the high temperature and the temperature set value into a plurality of zones and corresponding to each zone. Invented a circuit for converting the rotational speed of the compressor in response to the refrigeration and refrigeration load by configuring a signal to be transmitted to the frequency converter, which will be described in detail based on the drawings.

As shown in FIG. 1, a defrosting part (D) and a fan motor composed of a defrost operation switch (SW ₂ ) and a defrost heater (1) through an input power switching switch (SW ₁ ) and a power transformer (T ₁ ) from an AC power supply terminal. (2) is connected to the transistors Q ₁ , Q _{3 and} Q ₅ of the frequency converter A 'via the bridge rectifying circuit B, and the set temperature and high temperature of the temperature setting unit 3 are high. Signals such as the neon degree sensor 4, the temperature data of the refrigerant temperature sensor 5, the signal of the overcurrent detector T ₂ , the compressor duster 6 and the voltage detection resistor R, and the defrosting part bimetal 7 A control unit C having a microprocessor as an input is connected, and an output terminal thereof has a frequency conversion unit A 'composed of a power switching transistor Q ₁ -Q ₆ and a frequency conversion control circuit A. the transistor _{(Q 1, Q 3, Q} 5) of the emitter teodan That is, transistor _{(Q 2, Q 4, Q} 6) respectively connected to the collectors of the three-phase Motor (M) terminal 3 of the compressor It will cost.

Unmarked T ₃ is the step-down transformer, L is the swash lamp, SW ₃ is the door switch, F _{1 and} F ₂ are the power supply fuses, and F ₃ is the temperature fuse.

When the operation state of the present configuration configured as described above is described, the frequency setting signal of the digital signal displayed as an output is detected by detecting the difference between the set value of the temperature setting unit 3 and the temperature of the Gone temperature sensor 4 from the control unit C. When sent to the control circuit (A), the transistors (Q ₁ , Q ₂ ) and transistors (Q ₃ , Q ₄ ) connected to the three stages of the compressor three-phase motor (M), respectively, are set frequencies according to the difference between the high temperature and the set temperature. ) And the transistors Q ₅ and Q ₆ perform sequential switching operations, so that the compressor motor M is supplied with a three-phase alternating current (pulse output) having a set frequency, and this pulse output supplies the compressor motor M. In order to operate with high efficiency, the integral waveform is shaped to be a square waveform and the voltage is controlled to change almost in proportion to the frequency. The output frequency is continuously changed in the range of 30 Hz to 75 Hz. The rotation speed of the gear is also converted in the range of approximately 1700-4400rpm. Here, the digital signal applied to the frequency converter A ', that is, the frequency setting signal, is a temperature setting signal, a Gone temperature sensor, a refrigerant temperature sensor, and an overcurrent detector. A signal, such as a compressor voltage detection resistor of a compressor, is input to a microprocessor, is logically operated by a predetermined program, and then transmitted as a frequency setting signal.

On the other hand, in the defrosting function, after definite period of operation using the timer function in the microprocessor of the control unit C, the defrost switch SW ₂ is switched to the defrost heater 1 by the command signal of the control unit C, and thus defrosting. When the defrosting operation is completed, the defrosting bimetal 7 is operated to input a signal back to the control unit C to send a signal to the control unit C to the defrosting operation switch SW ₂ , and the fan motor 2. Switch to the side and restart the freezer / freezer.

Next, the process of converting the number of revolutions of the compressor motor corresponding to the load in a state in which the temperature difference between the high temperature and the set temperature is divided into a plurality of zones according to the second, third and fourth degrees.

TABLE 1

For example, by dividing the range according to the difference between the high temperature and the temperature set value into six zones (A, B, C, D, E, F) as shown in Table 6, the frequency set values corresponding to each zone are determined. The change of the operating frequency of the compressor according to the neon value and the temperature set value is shown in Fig. 2. Here, X is the area where the internal temperature decreases, and Y is the area where the internal temperature rises. In the A zone where the internal temperature is 1 ^o C or more higher than the temperature set point when the temperature starts to fall, a frequency setting signal of 75 Hz is applied so that the internal temperature drops sharply than the conventional freezer and refrigerator, and goes to the B zone below 1 ^o C. The frequency setting signal of 60 Hz is applied to the frequency converter A 'by the command signal from the control unit C, and the frequency setting signal of 40 Hz is applied when the internal temperature decreases and reaches the area (D). 0-0.5 degrees C ^o low state, that is, to set so that the frequency signal of 40Hz in the zone D continues to increase the refrigeration load is applied and transferred to the Durable 0-0.5 ^o C higher than the temperature set point temperature than the temperature set point Even if it is, this range becomes the zone D belonging to the region Y in which the internal temperature rises, so that a frequency setting signal of 40 Hz is continuously applied.

Therefore, since the set temperature of each zone has a difference of 0.5 ^o C between the region Y where the internal temperature rises and the region X which descends, the frequency setting signal frequently occurs after the internal temperature reaches the set value. It will not be converted and will continue to run smoothly.

Next, referring to FIG. 3 and FIG. 4, FIG. 3 illustrates a temperature and frequency conversion state under a relatively high load, and FIG. 4 illustrates a temperature and frequency change state under a relatively low load. As the graph shows, when the internal temperature is lower than the temperature setting, the operation is performed at the 40Hz frequency setting value in the D zone lower than the temperature setting value, and the load is small. Therefore, when the internal temperature keeps falling and reaches the E zone, the frequency setting signal of 35Hz is applied. .

Accordingly, if the temperature inside the zone is in the E zone until 3 minutes after continuing operation at the frequency of 35Hz, the operation is performed from time T ₅ to 30Hz, from which the temperature inside the temperature starts to rise, as the difference that the driving at 35Hz from time T ₆ leading to D zone of the area (Y), which raised the internal temperature, in this way extremely that when the load is small is to lower the operating frequency 5Hz prevent super-cooling, and the compressor is stopped Will be suppressed.

As described above, the present invention is to automatically adjust the refrigeration capacity according to each zone by dividing the high temperature conversion width, it is extremely limited to the ON / OFF operation of the compressor is consumed during the normal operation state at every start Unnecessary power consumption can be suppressed, and a significant energy energy effect can be expected, and since there are no frequent starting shocks of the indenter shaft, the reliability of the product is greatly improved, and the number of startups is extremely limited, resulting in noise generated at every startup. It is possible to operate quietly and quietly, and because the internal temperature is precisely controlled, it has various beneficial features such as giving a pleasant environment to the stored food.

Claims (2)

The defrosting part (D) and the fan motor (2) are connected to the power supply terminal, and the normal temperature setting part (3), the high temperature sensor (4), and the refrigerant temperature sensor (5) are connected via the bridge rectifier circuit (B). , A control unit (C) for detecting signals such as an overcurrent detector (T ₂ ), a compressor duster (6), a voltage detection resistor (R), a defroster bimetal (7), and a frequency converter (A) at its output terminal. Refrigeration capacity automatic adjustment refrigerator circuit corresponding to the load, characterized in that configured to connect to the three-phase motor (M) through '). 2. The frequency converter A 'according to claim 1, wherein the frequency converter A' is a frequency conversion control circuit A for controlling the frequency according to the output of the controller C, transistors Q ₁ , Q ₂ , (Q ₅ , Q _6). Characterized in that it is configured as).

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