JPS63251776A - 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 Application in the Nitrogen Industry 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 Application Laid-open No. 5
Publication No. 9-178989 and JP-A-69-181926
As shown in the publication, it has been proposed to start and operate the 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 above-mentioned conventional system, when switching the operation of the compressor from the inverter device to the original commercial power source, the output frequency of the inverter device is the same frequency as the commercial power source or the operating frequency. (for example, 901), and switching was performed without considering the power supply phase.

Therefore, in the former case, which switches at the same frequency, even if the phases happen to be synchronized, power is not applied to the compressor motor for a short time at the time of switching, so when the compressor rotation decreases and commercial power is next applied, as shown in Figure 5. As shown at the 60 ratio point, a slightly larger inrush current flows in the commercial power supply than the two points in Figure 5, which may cause an unnecessary width failure, and the capacity of the switching means should be selected to accommodate this inrush and E current. Therefore, the capacity of the switching means becomes large. Furthermore, since the phase at the time of switching is not near the zero-crossing point, excessive impact voltage and current are generated in the inverter device and the switching means due to arc discharge in the switching means. Furthermore, when the phases are not synchronized, as shown in Figure 4, the phases are out of 18, causing excessive current to flow to the compressor motor, damaging the motor, or causing excessive current to flow to the power supply wiring or switching means. It had a negative impact. In addition, the vibrations applied to the compressor were large at that time, and there was a possibility that not only the compressor would be damaged, but also the cooling system piping would break or leak.

In addition, when switching from the operating frequency (such as 901-lx) to commercial power, the compressor is braked suddenly from high speed to low speed and the motor enters regeneration mode, as shown in Figure 6-9.
01 (as shown at point z, a large inrush current flows through the commercial power supply, causing problems similar to those described above in mechanical systems such as the switching means, wiring system, and compressor).

Furthermore, when switching the compressor from inverter operation to commercial operation, for example, it is conceivable to stop the compressor and then start it with commercial power, but in this case, if you start it without waiting for the cooling system to stabilize, an overcurrent will flow and the protector will operate. The problem was that it took a long time to reboot.

In view of the above-mentioned problems, the present invention suppresses both the current and vibration when switching the operation of the compressor from an inverter device to a commercial power supply, downsizes the switching means, and controls the operation of refrigerators, etc. without having to stop the operation once. It provides equipment.

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 switching device for switching the voltage or current of the commercial power source to zero. a zero-cross detection circuit that detects a point at which When switching to the commercial power source, the output frequency of the inverter device is held higher than the frequency of the commercial power source, and the switching means is switched to the commercial power source near a waveform zero-crossing point of the inverter device.

Effect of the Invention With the above configuration, the present invention can minimize arc discharge in the switching means and prevent excessive shock current and voltage from occurring in the inverter device and the switching means when switching from an inverter device to a commercial power source. It suppresses the increase in vibration of the compressor and cooling system, and can be switched without stopping.

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, which is connected to the other terminal of the switching means 3, and includes diodes D1 to D4 connected in a bridge, a capacitor C2, and a transistor Q1 connected in a bridge.
~ 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 10 denotes a control circuit which takes in the outputs of the internal temperature comparator 6, rapid cooling switch 7, and cello cross detection circuit 8 as inputs, and outputs control signals to the inverter device 4 and the switching means 3. It's flowing.

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

FIG. 2 shows a timing diagram when switching from the commercial power source 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 or in normal operation, a signal is sent from the control circuit 9 to the switching means 3 and connected to the commercial power source 1 to operate the compressor 2 with the commercial power source 1. . When the inside of the refrigerator is cooled down to below the set temperature, a signal is sent from the comparator 7 to the control circuit 1o, and the control circuit 10 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 operation returns to the normal operation described above, and the compressor 2 is normally operated at 0N10FF using the commercial power supply 1 and the switching means 3 to maintain the temperature inside the refrigerator at a constant temperature.

Further, during normal operation, the switch means 6 is 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 10. The control circuit 1o receives this temperature rise signal, first sends a signal to the switch means 6 by the output of the zero cross detection circuit 9 to turn it on, and then sends a signal to the switching means 3 at the subsequent zero cross point, and turns on the switching means 3.
After switching to the inverter device 4 side, the compressor 2 is operated by the inverter device 4 by sending a transistor (01 to Q4) drive signal of a predetermined frequency to the inverter device 4. After switching to the inverter device 4, the inverter device 4 is operated at a high frequency to operate the compressor 2 at high speed, thereby rapidly cooling the inside of the refrigerator.

Next, when the inside of the refrigerator is cooled and reaches the set temperature, the control circuit 10 receives the change in the output of the comparator 7, stops the inverter device 4, and further turns off the switch means 5.
Compressor 2 is stopped.

Next, when the rapid cooling switch 8 is turned on during normal operation, the timing and timing of switching from the commercial power source 1 to the drive by the inverter device 4 are 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 the switch means 6 is turned on in the same manner as the above-mentioned hand neck. The commercial 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. After 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, and the rapid cooling operation in the refrigerator is completed.

Next, an explanation will be given of the operation when the rapid cooling switch 8 is turned on during normal operation and the rapid cooling is immediately canceled (the switch 8 is turned on again).

As shown in FIG. 3, the compressor 2 is driven at a frequency of 13 by the inverter device 4 until time t1. time t1
When the rapid cooling switch 8 is pressed, the transistors (Q, ~
Q4) When the drive frequency signal is gradually lowered and reaches a frequency 12 (for example, 601) higher than the frequency f1 of the commercial power supply 1 (for example, 601), it becomes point A, and at point A shown in FIG. 2, the control circuit 10 reaches a predetermined frequency f2.The control circuit 1o detects the rise of the output of the zero cross detection circuit 9 after point A, and the transistors (Q1 to Q
4) If the rising signal falls within the predetermined range (the phase range where the rising edge and zero cross occurs), a signal is output to the switching means 3 as shown at the end point in FIG. Stop signal. Furthermore, the switching means 3
There is a delay operation of the switching means 3 at 8 points with a delay of time TA.
The switching is completed and it is connected to the commercial power supply 1 side. Therefore,
The switching means 3 starts switching at the voltage zero cross point (sunshine) of the inverter device 4, and after the TA waiting time, switching to the phase-synchronized commercial power supply 1 is completed (convex point).
In particular, when the L load of the compressor 2 and motor is turned off, that is, when switching begins, the voltage is at zero cross, and the sparks generated at the contacts in the switching means 3 are extremely small. Therefore, from t2 (point C) onward in FIG. 3, it is operated with the commercial power supply 1.

As described above, according to this embodiment, the compressor 2 is connected to the commercial power supply
and an inverter device 4, a zero-cross detection circuit 9 that detects the point at which the bottom pressure or current of the commercial line tA1 becomes zero, and a signal from the zero-cross detection circuit S. A control means 10 is provided for switching the switching means 3 when the waveform zero cross phase of the inverter device 4 enters a predetermined range, and the compressor 2
When switching the operation from the inverter device 4 to the commercial power source 1, the output frequency of the inverter device 4 is held higher than the frequency of the commercial power source 1, and the switching means 3 is switched to the commercial power source near the zero-floss point of the waveform between the inverter device 4 and the commercial power source 1. Since the switch is made to the power supply 1 side, even if power is not applied to the compressor motor for a short time and the rotation of the compressor a2 decreases when switching, the rotation speed of the original inverter device 4 operation is still high, so the commercial power supply When switching to 2, the rotation is the same, the inrush current can be reduced, the capacity of the switching means 3 can be minimized, and unnecessary radiation of one wave can be prevented.

In addition, since the inverter device 4 does not suddenly switch from an illegal frequency (such as 90 kHz) to the commercial power supply 1, the compression speed 2 does not suddenly become low speed, and the power supply wiring, switching means 3, and voltage W3 No inrush current or impact is applied to the two mechanical systems, and reliability can be improved with minimum capacity.

Furthermore, since the phases are synchronized and switching is performed at the zero cross point, no contact sparks or impact currents flow in the switching means 3, so the switching means 3 can be made with a small capacity and its reliability can be improved. Also in the inverter device 4, the impact voltage and current caused by this snork can be minimized, and the capacity of the transistors (01 to Q4) of the inverter device 4 can be minimized.

Furthermore, the reliability of the compressor 2, motor, and power supply wiring can be improved.

In addition, even if the quick freezing switch 8 is turned on or off at the last minute, it is possible to switch from the inverter device 4 to the commercial power supply 1 without stopping the compression stage 2, so there is no need to wait for a restart at the last minute. Fortunately, the temperature inside the refrigerator does not rise even with the above mischievous operation, and the quality of the refrigerator can be maintained.

Furthermore, since the frequency of the inverter device 4 is made higher than the frequency of the commercial power source 1, the zero-crossing point and the timing of phase synchronization arrive earlier than in a frequency-same switching system, so that switching can be achieved quickly in response to requests.

Note that the zero-cross detection circuit 9 is not limited to the above-mentioned embodiment, but 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 includes a switching means for switching a compressor to be driven by either a commercial power source or an inverter device, and a zero-cross detection device for detecting a point where the voltage or current of the commercial power source becomes zero. and a control means for switching the switching means when the signal from the zero-crossing detection circuit falls within a predetermined range of the waveform zero-crossing phase of the inverter device, and when switching from the inverter device to the commercial power source, the output frequency of the inverter device is changed to that of the commercial power source. The frequency is maintained higher than the frequency, and the switching means is switched to the commercial power supply side near the zero cross point of the waveform between the inverter device and the local power supply, so when switching, power is not applied to the compressor motor for a short period of time, and the compressor rotates. Even if the power decreases, the original rotational speed of the inverter device remains high, so when switching to commercial power, the rotational speed remains the same, reducing inrush current and minimizing the capacity of the switching means. In addition, unnecessary radio wave radiation can be prevented.

In addition, since the inverter does not suddenly switch from the operating frequency (901, etc.) to the commercial power supply, the compressor does not suddenly slow down, and the power supply wiring, switching means, and compressor mechanical system are No inrush current or impact is applied,
Reliability can be improved with minimum capacity.

Furthermore, since the phases are synchronized and switching is performed at the zero cross point, contact sparks and inrush currents do not flow in the switching means, so the switching means can be made with a small capacity and reliability can be improved. However, the impact voltage and current generated by this spark can be minimized, and the capacity of the inverter device can be minimized. Furthermore, the reliability of the compressor motor and power supply wiring can be improved.

Furthermore, since the zero-cross point and phase synchronization timing arrive early, switching can be achieved quickly in response to requests.

[Brief explanation of the drawing]

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. Timing diagram No. 4 (2) is a characteristic diagram of voltage and current at the time of switching, and FIG. 5 is a characteristic diagram of switching frequency and current.・ 1...Commercial power supply, 2...Compressor,
3...Switching means, 4...Inverter device, 9...Zero cross detection circuit, 1o...
...control means. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure I Rono ＼ Figure 3 Stopper 1 hour review

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 switching the switching means when the signal of the zero-crossing detection circuit falls within a predetermined range of the waveform zero-crossing phase of the inverter device, and when switching from the inverter device to the commercial power source. An operation control device for a refrigerator or the like, characterized in that the output frequency of the inverter device is maintained higher than the frequency of the commercial power source, and the switching means is switched to the commercial power source side near a waveform zero cross point between the inverter device and the commercial power source.