JPH06101652A - Refrigerating device - Google Patents

Abstract

PURPOSE:To invariably operate a refrigerating device at high efficiency by invariably keeping the revolving speed of a compressor at high efficiency. CONSTITUTION:A refrigerating device is provided with an inverter device 23, a compressor 1, a frequency detecting means 6, a controller 28 determining the difference between the actual revolving speed of a motor detected by a detecting means and the target revolving speed corresponding to the frequency, and a switching section 27 for eliminating the difference between both revolving speeds. The switching section 27 adjusts the voltage of the AC power, and the actual revolving speed of the motor is adjusted to the efficient target revolving speed corresponding to the frequency. This refrigerating device is invariably operated at high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having an inverter device for supplying AC electric power whose voltage and frequency are controlled to an electric motor of a compressor.

[0002]

2. Description of the Related Art Generally, as a refrigerating device having a variable speed compressor, there is a refrigerating device disclosed in Japanese Utility Model Publication No. 2-28353, which discloses an inverter according to a load condition. It is equipped with an inverter device that changes the voltage and frequency of the power supply.

[0003]

In the above-mentioned refrigerating apparatus, the voltage / frequency value is controlled so as to become a predetermined value, but it is the same depending on the magnitude of the load (for example, the difference between the set temperature and the room temperature). Since the rotational speed of the compressor electric motor cannot be controlled to be constant even with the applied voltage, the rotational speed of this electric motor deviates from the most efficient range, and the electric motor was operated at a low effective rotational speed. Further, the voltage output from the inverter device to the compressor electric motor may fluctuate due to the fluctuation of the voltage of the commercial power supply, which may cause the electric motor to be operated at an inefficient rotation speed. For this reason, the refrigeration system, which largely depends on the efficiency of the compressor, cannot always be operated in a highly efficient state.

The present invention constantly operates the refrigeration system with high efficiency by keeping the number of revolutions of the compressor in a highly efficient state.

[0005]

The present invention relates to a refrigeration system provided with an inverter device for controlling the voltage and frequency of AC power based on a refrigeration load, and a compressor driven by the output from this device. Rotational speed detection means for detecting the actual rotational speed of the electric motor of the compressor, computing means for obtaining the difference between the actual rotational speed of the electric motor detected by the detection means and the target rotational speed corresponding to the frequency, And an adjusting means for eliminating the difference in rotation speed.

[0006]

In this refrigeration system, the calculating means calculates the difference between the actual rotation speed of the electric motor detected by the rotation speed detecting means and the target rotation speed corresponding to the frequency, and the adjusting means is provided to eliminate this difference in rotation speed. For example, the voltage of AC power is adjusted.

[0007]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a refrigerant circuit diagram of a refrigerating apparatus of the present invention, which has a variable capacity compressor 1, a four-way valve 2 for switching a refrigerant flow path, an indoor heat exchanger 3, and a pressure reducer 4. Outdoor heat exchanger 5
And are sequentially connected by a refrigerant pipe to form a heat pump type refrigeration cycle.

Reference numeral 6 is a rotation speed detecting means for detecting the rotation speed of the electric motor in the compressor 1 per unit time, and for example, a Hall element or a Hall IC, a search coil, a magnetic detection element such as a magnet wire is used.

The details of the rotation speed detecting means 6 are shown in FIG. 3, and 7 is a rotor of the induction motor 8, which rotates about a rotating shaft 9.

Reference numeral 10 denotes a rotating disk, which is connected to the center of the rotating shaft 9 by a bolt 11. A permanent magnet 12 is mounted on the disc 10. 13 is a balance weight,
The disk 10 is provided at a position symmetrical to the center of rotation of the disk 10.
Is the weight of the field lance with the permanent magnet 12 when rotating. Reference numeral 14 is a stator of the electric motor.

Reference numeral 15 is a bottomed copper pipe, which is inserted from the outside of the compressor 1. At this time, the copper pipe 15 is hermetically attached so that the high-pressure refrigerant in the compressor 1 does not leak outside. A magnetic detection element, for example, a search coil 17 wound around ferrite is attached to the tip of the copper pipe 15 (bottom of the copper pipe). This search coil 1
7 detects the magnetic flux of the permanent magnet 12 and changes the output signal. Therefore, an output signal is obtained every time the rotor 8 makes one revolution.
Reference numeral 16 is a lead wire, which is connected to the search coil 17. This copper pipe has a lead wire 16 and a search coil 17.
After housing, the epoxy resin is encapsulated.

Reference numeral 18 is a gasket, and 19 is a rubber cap for closing the opening of the copper pipe 15. 20 is a fixing bolt of the rotation signal output unit 7, 21 is a compressed refrigerant discharge pipe, and 22 is a fixing metal fitting of the accumulator.

Reference numeral 23 is an inverter device for inputting a signal from the rotation speed detector 6 and supplying AC electric power whose voltage v and frequency f are controlled to the electric motor 8 in the compressor 1.

FIG. 2 shows a block diagram of an inverter device. In this inverter device 23, first, an AC power source 24
Is converted into direct current by the rectifier circuit 25, and this direct current is smoothed by the smoothing circuit 26 including a smoothing capacitor to reduce ripples and supplied to the switching unit 27 [adjusting means] including a plurality of switching elements. ing.

In the switching section 27, a pseudo sine wave alternating current is generated by turning on / off individual switching elements and is supplied to the compressor electric motor 8. This switching element is turned on / off by a signal from the control unit 28 [arithmetic means and adjusting means]. Control unit 28
Is powered by a constant voltage circuit 29 that obtains a DC voltage from the AC power supply 24.

The control unit 28 has a ROM in which ON / OFF timings of switching elements are stored in advance,
It is composed of a CPU and the like for extracting the contents of the ROM.

O of the switching element stored in the ROM
The N / OFF timing is set so that the output frequency of the switching unit 27 and the target rotation speed have a linear relationship as shown in FIG. This is obtained by plotting the number of revolutions N [target number of revolutions] at which the efficiency of the electric motor 8 at the output frequency f to the electric motor 8 is almost maximum every 1 Hz, and the result is shown in FIG.
The linear expression shown in, that is, N = a × f−b (rpm) [a,
This is because it has been confirmed that it can be expressed by the equation b is a constant]. The output voltage is adjusted so as to satisfy the relation of this linear expression, and the actual rotation speed n of the electric motor 8 is controlled so as to approach N.

Further, the relation between the frequency and the target rotation speed is stored in the ROM of the control unit 28 by this linear expression, and the control unit 28 calculates the target rotation speed N corresponding to the frequency f each time. Therefore, it is possible to cope with the increase in the storage capacity of the ROM.

Then, the control unit 28 operates based on the flowchart shown in FIG.

That is, the control unit 28 constantly inputs the signal from the rotation speed detection means 6, and if the rotation speed n of the electric motor 8 is within the range of the target rotation speed N ± 10 rpm, the output voltage v can be adjusted. Not performed. If the rotation speed n of the electric motor 8 is not within the above range, the rotation speed n is N ± 10 rpm.
The voltage v output to the electric motor 8 is increased or decreased so as to fall within the range [efficiency does not significantly decrease at ± 10 rpm]. The interval at which this adjustment is performed is, for example, every 0.5 seconds.

FIG. 5 shows the basic relationship between the frequency f and the voltage v. When the frequency f is from 10 Hz to F0 Hz, the ratio between the frequency f and the voltage v is controlled to be constant, and when the frequency is F0 Hz or higher, the voltage v is maintained constant. When the frequency f is equal to or lower than F0, the voltage v corresponding to the frequency f is output to the electric motor. However, due to the size of the load and the voltage fluctuation of the commercial power source, the actual rotational speed n of the electric motor is n.
May deviate significantly from the efficient rotation speed. For example, when the voltage of the commercial power source becomes higher than 100v or when the load is small, the rotation speed detection means has a higher actual rotation speed n.
Since the output voltage v is detected, the output voltage v is adjusted to be low by the adjusting means [refer to the straight line A, it may be considered that F0 is set large]. Further, when the voltage of the commercial power source becomes lower than 100v or when the load is large, the rotation speed detection means detects a lower actual rotation speed n, so that the adjustment means adjusts the output voltage v to be high [ See straight line B, F
You may think that 0 is set small]. In this way, the output voltage v is adjusted to be low or high by the adjusting means, so that the actual rotation speed n corresponds to the frequency f and is set in advance to the target rotation speed N [corresponding to the frequency f. The rotation speed at which the efficiency of the electric motor is almost maximized] is adjusted.

In the refrigeration system thus constructed, the control unit 28 of the inverter device 23 operates as shown in the flow chart of FIG.

First, the control unit 28 inputs the actual rotation speed n of the electric motor 8. Next, when the load [for example, the difference between the set temperature and the actual temperature] varies, the output frequency f corresponding to this load is calculated. Then, the target rotation N corresponding to this output frequency f is calculated. When the actual rotation speed n is larger than the target rotation speed N + 10, the output voltage v is set to 0.0
The actual rotation speed n is reduced by 1 v and adjusted so that the actual rotation speed n approaches the target rotation speed N. When the actual rotation speed n is smaller than the target rotation speed N-10, the output voltage v is increased by 0.01v so that the actual rotation speed n approaches the target rotation speed N.

In this refrigeration system, the inverter device 23
When the voltage to be output to the electric motor 8 for the compressor 1 fluctuates and the actual rotation speed n of the electric motor 8 fluctuates, the control unit 28 outputs an output voltage v that achieves the target rotation speed N according to the output frequency f. Since the fine adjustment is performed, the electric motor 8 always outputs a voltage that maximizes the efficiency. Therefore, the compressor 1
The efficiency of the refrigeration system can be increased, and the efficiency of the refrigeration system can be increased. According to the experiments, it was confirmed that the refrigerating apparatus of the present invention reduced the power consumption by about 5% as compared with the conventional refrigerating apparatus.

Since the relationship between the frequency f and the target rotational speed N at which the efficiency is substantially maximum corresponding to this frequency is calculated, the actual rotational speed n detected by the rotational speed detecting means 6 is calculated as the target rotational speed n. Considering the number N, the frequency f may be controlled to a frequency corresponding to the target number of revolutions N without controlling the actual number of revolutions n, and in this case as well, power consumption can be reduced.

[0027]

The present invention provides an inverter device for controlling the voltage and frequency of AC power based on a refrigeration load,
In a refrigeration system including a compressor driven by an output from this device, a rotation speed detection unit that detects an actual rotation speed of the electric motor of the compressor, and an actual rotation speed of the electric motor that is detected by the detection unit. Since the calculation means for obtaining the difference from the target rotation speed corresponding to the frequency and the adjusting means for eliminating the difference between the both rotation speeds are provided, the actual rotation speed and the frequency of the electric motor detected by the rotation speed detection means. Is calculated by the calculating means, and the adjusting means adjusts the voltage of the AC power, for example, so as to eliminate the difference in the rotational speed. The actual speed is adjusted. Therefore, according to the present invention, the compressor can always be operated at a highly efficient rotation speed, and by extension, the refrigeration system can always be operated in a highly efficient state. Can be reduced.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system showing an embodiment of the present invention.

FIG. 2 is a block diagram of an inverter device of the refrigeration system.

FIG. 3 is a cross-sectional view of essential parts showing a compressor of the refrigeration apparatus.

FIG. 4 is a diagram showing a relationship between a frequency of the refrigeration system and a target frequency.

FIG. 5 is a diagram showing a relationship between frequency and voltage of the refrigeration system.

FIG. 6 is a flowchart showing an operation of the refrigerating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 6 Rotation speed detection means 8 Electric motor 23 Inverter device 27 Switching part [Adjusting means] 28 Control part [Calculating means and adjusting means]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akihiro Suda 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A refrigeration system comprising an inverter device for controlling the voltage and frequency of AC power based on a refrigeration load, and a compressor driven by the output from this device,
Rotational speed detection means for detecting the actual rotational speed of the electric motor of the compressor, computing means for obtaining the difference between the actual rotational speed of the electric motor detected by the detection means and the target rotational speed corresponding to the frequency, A refrigerating apparatus comprising: an adjusting unit for eliminating a difference in rotation speed.