JPS63251775A - Controller for operation of refrigerator, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an operation control device for a refrigerator or the like that controls a compressor by switching between a commercial power source and an inverter device to vary its capacity.

Conventional technology In recent years, for refrigeration equipment such as refrigerators, for example, Japanese Patent Laid-Open No. 6
As shown in Japanese Patent No. 0-"+ 90190, it has been proposed to start and operate a compressor using a commercial power source, and switch to an inverter device to drive the compressor when necessary, thereby changing its cooling capacity.

Problems to be Solved by the Invention However, in the conventional system described above, when switching from a commercial power source to an inverter device, the output frequency of the inverter device is set to the same frequency as the commercial power source or a target frequency (for example, 90-an). . Therefore, in the former case, due to variations in the output frequency of the inverter, it may become lower than the frequency of the commercial power supply, and in that case, the compressor motor will go into regeneration mode, causing the power elements of the inverter to operate as shown in Figure 4. As shown, a large current may flow. FIG. 4 is a characteristic diagram of switching frequency and current. If the current increases, the power device may be destroyed or deteriorated, or an expensive power device with a large capacity will be required. At that time, the vibrations applied to the compressor were also strong enough to cause leaks or breaks in the piping of the cooling system.

In the latter case, a large inrush current flows, posing the same problem as described above. Further, the compressor and cooling system also had the same problems as mentioned above.

In view of the above-mentioned problems, the present invention provides an operation control device for a refrigerator, etc., which suppresses both current and vibration when switching from a commercial power source to an inverter device, improves reliability of power elements, and reduces size.

Means for Solving the Problems In order to solve the above problems, the operation control device for a refrigerator, etc. of the present invention includes a switching means for switching between an inverter device and a commercial power source, and a voltage or current of the commercial power source becomes zero. A zero-crossing detection circuit for detecting a point, and a control means for controlling the switching means based on a signal from the zero-crossing detection circuit and generating a drive signal for the inverter device, and a control device for switching from the commercial power source to the inverter device. At the same time, the output frequency of the inverter device is made higher than the frequency of the commercial power source.

Effect of the Invention With the above-described configuration, when switching from a commercial power source to an inverter device, the present invention makes the output frequency of the inverter higher than the frequency of the commercial power source, thereby suppressing the increase in current and vibration caused by variations in the output frequency of the inverter device. It can be suppressed.

Embodiment Hereinafter, an operation control device for a refrigerator or the like according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit block diagram of an operation control device for a refrigerator or the like in one embodiment of the present invention. The refrigeration cycle part has been omitted to simplify the explanation. In FIG. 1, 1 is a commercial power source. 2
is a compressor, which is connected to a commercial power source 1 via a switching means 3 when the compressor 2 is started up and during normal operation. 4 is an inverter device connected to the other terminal of the switching means 3, and includes bridge-connected diodes D1 to D4, a smoothing capacitor C1, and a bridge-connected transistor 01.
~Consists of Q4. Reference numeral 6 denotes a switch means arranged between the inverter device 4 and the commercial power supply 1. Reference numeral 6 denotes a temperature detector for detecting the internal temperature of a refrigerator or the like, which compares the temperature with a set temperature using a comparator 7 and sends out a signal. 8 is a switch which is operated when it is desired to rapidly cool down the inside of a refrigerator or the like.

9 is a zero cross detection circuit that detects the point where the voltage of the commercial power supply 1 becomes zero volts and sends out a signal. Reference numeral 1o denotes a control circuit, which receives the outputs of the internal temperature comparator 6, rapid cooling switch 7, and zero-cross detection circuit 9 as inputs, and is connected to the inverter device 4 and the delay means 11 so as to output control signals. ing. The output of the delay means 11 is connected to the switching means 3.

The operation of the operation control device for a refrigerator or the like configured as described above will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows a timing diagram when switching from the commercial power supply 1 to the inverter device 4 output in the configuration of FIG. 1. FIG. 3 shows a timing chart showing changes over time in the frequency input to the compressor 2 in the configuration of FIG. In FIG. 1, when the compressor 2 of a refrigerator or the like is started up and during normal operation, a signal is sent from the control circuit 9 to the switching means 3 and the commercial power source 1
The compressor 2 is connected to the side and operated with the commercial power supply 1. When the inside of the refrigerator is cooled to below the set temperature, a signal is sent from the comparator 7 to the control circuit 1o, and the control circuit 1o switches the switching means 3 to the inverter device 4 side, thereby stopping the compressor 2. Next, when the temperature inside the refrigerator rises, the above-mentioned normal operation is resumed, and the compressor 2 is normally turned OFF by the switching means 3 using the commercial power source 1 to maintain the temperature inside the refrigerator at a constant temperature. Further, during normal operation, the switch means 6 is turned off and the inverter device 4 is not energized.

Next, when the temperature inside the refrigerator rises abnormally, when the comparator 7 exceeds a predetermined upper limit temperature setting value, an abnormal temperature rise signal is sent to the control circuit 1o. The control circuit 1o receives this temperature rise signal, first detects the zero cross point shown in FIG. 2(a) of the output of the zero cross detection circuit 9, and sends a signal to the switch means 6 to turn it on. Next, the control circuit 1o outputs a signal to the delay means 11 at the first zero-crossing point (shown in FIG. 2(b)) of the zero-crossing detection circuit 9. At this time, as shown in FIG. 2, the output signal of the delay means 11, that is, the drive signal of the switching means 3, is delayed by a time TA. Furthermore, there is a delay operation of the switching means 3 itself, and the contacts of the switching means 3 operate after a time TB (as shown in FIG. 2(C)). Here, the delay time TA of the delay means 11 is set in advance, and TA+TB becomes a half cycle, and the operation of the contact of the switching means 3 is switched at a point half a cycle after the first zero cross point. Next, at a second zero-crossing point (shown in FIG. 2) one cycle after the first zero-crossing point, the control circuit 10 transmits the signal to the inverter device 4 at a frequency higher than the frequency of the commercial power supply (for example, in the case of a commercial power supply of 60 yen). 61Hz). As a result, the voltage applied to the compressor 2 is
The switching means 3 switches at zero volts, and after a half cycle, the switch jig waveform of the inverter device 4 is supplied.

In other words, switching can be performed with minimal instantaneous interruption.

After switching to inverter device 4, inverter device 4
By operating at a high frequency, the compressor 2 is operated at high speed and the inside of the refrigerator is rapidly cooled.

If we look at the above operation over time, it becomes as shown in Fig. 3.

It is driven by commercial power (frequency f1) until time t1. At time t1, the commercial power source is switched to the inverter device (output frequency f2). After time t1, the output frequency of the inverter device is gradually increased, and operation continues at the highest frequency f3 at time t2. Next, when the inside of the refrigerator is cooled and reaches the set temperature, the control circuit 9 receives the change in the output of the comparator 6, stops the inverter device 4, and then turns off the switch means 6, thereby stopping the compressor 2. let

Next, when the rapid cooling switch 8 is turned on during normal operation, the procedure for switching from the commercial power supply 1 to the drive by the inverter device 4 is the same as when the temperature inside the refrigerator increases. If this switch 8 is turned on while the compressor 2 is stopped, the control circuit 10 switches the switching means 3 to the commercial power supply 1 side and starts the compressor, and then turns on the switch means 6 in the same manner as the above procedure, The power source 1 is switched to drive by the inverter device 4, and then the compressor 2 is operated at high speed to rapidly cool the inside of the refrigerator. When a predetermined period of time has elapsed, the inverter device 4 is stopped by a signal from the control circuit 9, the compressor 2 is stopped,
The rapid cooling operation in the refrigerator is completed.0 As described above, according to this embodiment, the compressor 2 is connected to the commercial power source 1.
and an inverter device 4, and a zero-cross detection circuit 9 that detects the point at which the voltage or current of the commercial power source 1 becomes zero.
and a delay means-1 for delaying the operation of the switching means 3, and a delay means-1 for controlling the switching means 3 by the first signal of the zero-cross detection circuit 9 via the delay means 11 and a second signal of the zero-cross detection circuit 9. By providing a control circuit that generates a drive signal so that the output frequency of the inverter device 4 is higher than the frequency of the commercial power supply 1, the compressor motor can be adjusted even if the output frequency of the inverter device 4 varies. does not go into regeneration mode, the current flowing through the transistors Q1 to Q4 of the inverter device 4 can be suppressed to a low level, and the reliability of the transistors can be significantly improved, and even lower current transistors can be used. Miniaturization/
Cost can be reduced. There is also no vibration when entering regeneration mode, reducing stress on the cooling system and preventing pipe leaks and bends. In addition, since an inexpensive relay can be used as a switching means, it not only contributes to cost reduction, but also prevents the radiation of necessary radio waves by operating near the zero cross of voltage or current, and further reduces the size of the relay. can improve reliability and reliability.

Note that the zero-cross detection circuit 8 is not limited to the above-mentioned embodiment, and is assumed to detect the current in one line of the commercial power supply 1, detect the point where the value becomes zero, send out a signal, and control in the same procedure as in the above-mentioned embodiment. It's okay.

Furthermore, in the above embodiment, the case where the compressor 2 is operated at high rotation speed has been described, but when the cooling capacity is not so necessary, such as when the outside temperature is low, it is also possible to operate the compressor 2 at low rotation speed to reduce power consumption. good.

Effects of the Invention As described above, the present invention has a switching means for switching between an inverter device and a commercial power source, a zero-cross detection circuit for detecting a point where the voltage or current of the commercial power source becomes zero, and a signal from the zero-cross detection circuit. By providing a control means that controls the switching means and generates a drive signal having a higher frequency than the frequency of the commercial power supply, the output frequency of the inverter device can be compressed even if the output frequency of the inverter device varies. The machine's motor does not go into regeneration mode, and the current flowing through the power elements of the inverter device can be kept low, making it possible to achieve high reliability and low cost. In addition, the vibration applied to the compressor is reduced, leading to improved reliability of the cooling system.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of an operation control device for a refrigerator or the like according to an embodiment of the present invention, Fig. 2 is a timing diagram for the configuration shown in Fig. 1, and Fig. 3 shows changes over time in the input frequency of the compressor. The timing diagram, FIG. 4, is a characteristic diagram of switching frequency and current. 1...Commercial power supply, 2...Compressor, 3...
...Switching means, 4...Inverter device, 6
. . . Switch means, 9 . . . Zero cross detection circuit, 10 . . . Control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
Figure 3 Mu i, l t2 Haruma Figure 4 Dual-use power supply

Claims (1)

[Claims] an inverter device that converts the frequency of a commercial power source; a switching device that switches the compressor to be driven by either the inverter device or the commercial power source; and a point where the voltage or current of the commercial power source becomes zero. a zero-crossing detection circuit; and a control means for controlling the switching means and generating a drive signal for the inverter device based on a signal from the zero-crossing detection circuit, and when switching from the commercial power source to the inverter device, the inverter device An operation control device for a refrigerator or the like whose output frequency is set to be higher than the frequency of the commercial power source.