JPH07103555A - Operation controlling method for compressor - Google Patents

Abstract

PURPOSE:To perform an operation of an energy conservation by judging whether a load of a refrigerating cycle falls within a specific range or not, and lowering a voltage without altering a frequency of an AC current to be supplied to an induction motor for a compressor when it falls within the range. CONSTITUTION:A frequency command value (f) is input from an indoor unit 370 to a microprocessor 39 of an outdoor unit 371. The microprocessor 39 judges whether the value (f) falls within a specific range of a frequency F or not. When the value (f) falls within the range, a read current value is compared with a set value. When the value (f) is the set value or less, a read temperature is compared with a set temperature. When it is the set temperature or lower, a present current value Inow is input based on a detection signal of a CT 53, and then a voltage command value is so altered and set as to lower the power. After a specific time is elapsed, a current value Inext at the time is read from the CT, 53. The operation is repeated until (Inow-Inext) is 0 is satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor operation control method, and more particularly to an operation control method for efficiently operating an induction motor which is a drive source of a compressor used in a refrigeration cycle mounted in an air conditioner or the like. Regarding

[0002]

2. Description of the Related Art Conventionally, most compressors mounted in an air conditioner use an induction motor as a rotary drive source, and its operation control is known to be of an inverter type. In this inverter system, the rotation speed (capacity) of the compressor is controlled by changing the frequency F of the AC power supplied to the induction motor,
The operation capacity was obtained according to the load of the refrigeration cycle. At this time, the voltage V of the AC power (the pseudo voltage generated in the stator winding of the induction motor when the PWM inverter device is used) is V / F even if the frequency F is adjusted according to the load. The ratio of was always preset.

Particularly, in the PWM type inverter device,
The ON / OFF pattern of the switching element is generally set in advance according to the frequency F and stored in the ROM. Since the amount of ON / OFF patterns that can be stored in the ROM is limited, the value of the voltage V is set and stored so as to correspond to the frequency F in a one-to-one relationship to reduce the amount of ROM usage.

[0004]

In the above-described conventional compressor operation control method, the frequency F is controlled while the V / F ratio is always kept constant. Considering the fluctuation, set the value of V / F higher,
The compressor was prevented from locking when the load fluctuated in the increasing direction. Therefore, of course, there is a problem that the operating efficiency decreases when the load is light.

In order to eliminate this decrease in operating efficiency, a method has been disclosed in which the power factor of the AC power supplied to the induction motor is obtained and the voltage is controlled so that this power factor becomes the maximum (Japanese Patent Laid-Open No. Sho 60-96). No. 61-20236).

However, in the case of this control method for obtaining the power factor of AC power, if the AC waveform supplied to the electric motor has distortion (particularly due to harmonics), the accuracy of detecting the power factor will be extremely reduced, and the operation will be reduced. The efficiency cannot be improved sufficiently.

That is, when a pseudo sine wave (AC waveform obtained by switching a DC voltage based on the PWM theory) generated by an inverter circuit is supplied to the motor, the pseudo sine wave is generated by the inductance of the stator winding of the motor. Is smoothed to some extent, but distortion still remains in the current waveform, resulting in a decrease in detection accuracy as described above. This inconvenience is particularly remarkable in the case of a small output electric motor (several kW or less) because the waveform distortion rate becomes large.

Therefore, a method is also known in which slip is detected from the waveform of the current flowing through the electric motor, and the terminal voltage of the electric motor is controlled so that the slip has a predetermined value to improve the operating efficiency (Japanese Patent Laid-Open No. 4-33584). See the bulletin). The smaller the slip, the higher the operating efficiency.

However, even in this case, if the above-mentioned distortion remains in the current waveform, the slip detection accuracy varies, and the control of the terminal voltage becomes unstable. Further, although it is possible to suppress the variation in detection to some extent by increasing the circuit capability of the detection circuit, the detection circuit becomes significantly complicated and the cost of its parts also increases significantly.

The present invention has been made in view of such a conventional problem, and in particular, the voltage V applied to the compressor is finely adjusted according to the operating state of the air conditioner while keeping the frequency F constant. The main object of the present invention is to provide an operation control method capable of improving operation efficiency and saving energy.

[0011]

In order to achieve the above object, the operation control method for a compressor according to the present invention comprises a refrigeration cycle using a compressor, a condenser, a decompression device, and an evaporator. In the operation control method of the compressor that arbitrarily changes the frequency of the AC power supplied to the induction motor mounted as the rotation source in the compressor, it is determined whether the load of the refrigeration cycle is within a predetermined range, and the load is When the range is satisfied, the voltage (V) is reduced without changing the frequency (F) of the AC power.

In the range, the frequency of the AC power is within a set range, the current of the AC power is less than or equal to a set value, and the space temperature when air-conditioning a predetermined space by the refrigeration cycle is It is characterized by being less than a set value.

[0013]

According to the present invention, the frequency of the AC power is adjusted according to the size of the load, and the capacity of the compressor is controlled. On the other hand, when the load is relatively light (for example, the frequency of the AC power is within the set range, the current is below the set value, and the room temperature during air conditioning is below the set value),
The voltage is appropriately lowered while keeping the frequency F constant. As a result, the slip of the induction motor is adjusted, the current value is reduced, and the operation is highly efficient.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a refrigeration cycle using a compressor is installed in an air conditioner.

FIG. 1 is a schematic diagram of an air conditioner according to this embodiment. In the figure, reference numeral 5 indicates a hermetic compressor. The compressor 5 includes a compressor body 6 that compresses a refrigerant and a three-phase AC induction motor 1 that drives the compressor body 6 to rotate.
It consists of and. Further, reference numeral 23 is a four-way switching valve, 24 is a heat source side heat exchanger, 25 to 27 are pressure reducing devices (for example, capillary tubes), 28 is a strainer, 29 is a use side heat exchanger, and 30 is an accumulator. These elements are connected through a refrigerant pipe to form a refrigeration cycle.

When the four-way switching valve 23 is in the switching position shown in FIG. 1, the compressed refrigerant discharged from the compressor 5 flows in the direction of the solid line arrow, the heat source side heat exchanger 24 functions as a condenser, and Since the use side heat exchanger 29 functions as an evaporator, the use side heat exchanger 29 can be used to perform the cooling operation on the use side, for example, the room. In addition, the four-way switching valve 23
Is switched as indicated by the dotted line, the compressed refrigerant discharged from the compressor 5 flows in the direction of the dotted arrow, this time the utilization side heat exchanger 29 functions as a condenser, and the heat source side heat exchanger 2
Since 4 functions as an evaporator, the heating operation of the room can be performed by the use side heat exchanger 29.

Reference numerals 31 and 32 in the drawing are silencers, 33 is a propeller fan for blowing air to the heat source side heat exchanger 24, and is driven by an electric motor 34. Reference numeral 35 denotes a crossflow fan that supplies conditioned air that has been heat-exchanged (heated / cooled) by the use-side heat exchanger 29 into the room, and is driven by the electric motor 36.

Further, reference numeral 370 indicates an indoor unit, and the indoor side unit 370 includes a utilization side heat exchanger 29,
Cross flow fan 35, electric motor 36, indoor control unit 3
7 etc. are installed. Other devices are mounted on the outdoor unit 371. The outdoor unit 371 and the indoor unit 370 are mutually connected by a refrigerant pipe and a signal line.

The indoor unit 370 outputs, to the outdoor unit 371, signals for operating and controlling the equipment arranged in the outdoor unit 371, including a signal for controlling the frequency F of the AC power supplied to the electric motor 1 of the compressor 5. . In the outdoor unit 371, the signal from the indoor unit 370 is
First, it is inputted through the interface 38 and given to the microprocessor 39 as a control unit.

The microprocessor 39 controls the operation of the outdoor unit 371 based on the input signal, and P
A switching signal is generated to obtain a pseudo sine wave based on the WM theory. The generation of this switching signal will be described later. The switching signal generated by the microprocessor 39 is supplied to the inverter circuit 40 via the switching amplifier 41.

As shown in FIG. 2, the inverter circuit 40 includes six power switching elements X, X bar, Y,
It has a circuit configuration in which Y bars, Z, and Z bars are connected in a three-phase bridge shape, and DC power is applied to the P terminal in the figure. A power transistor, a power FET, an IWGT, or the like can be used as the six power switching elements. These six switching elements are turned on / off in response to the switching signal, and a three-phase pseudo sine wave is generated by the motor 1
Supply to.

The DC power supplied to the inverter circuit 40 is obtained from the AC power supply 42. That is, the single-phase AC of the AC power supply 42 is rectified by double voltage to generate DC power. Double voltage rectification is performed by the rectifying element 43 and the smoothing capacitor 44
At 45. In FIG. 1, reference numeral 46 is a smoothing capacitor after voltage doubler rectification, 47 is a choke coil, and 48, 49.
Is a noise filter, 50 and 51 are current fuses, and 5
2 is a varistor.

FIG. 3 is a principle diagram showing the generation of a switching signal by the microprocessor 39, and illustrates the case where an ON / OFF signal (switching signal) is obtained by the switching elements X and X bar shown in FIG. The ON / OFF signal of the switching element X is an inverted version of the ON / OFF signal of the switching element X.

In the upper part of FIG. 3, one waveform C0 shows a carrier wave (for example, triangular wave, stepwise triangular wave, limit wave), and the other waveform M0 shows a modulated wave (for example, sine wave, stepwise sine wave). . The ON / OFF signal S0 is determined by the amplitudes of the carrier wave C0 and the modulated wave M0, and the modulated wave M0>
When the carrier wave is C0, the ON / OFF signal S0 is ON.
The frequencies and frequency ratios of the carrier wave C0 and the modulated wave M0 are not limited to those shown in FIG. 3, and the frequencies are easy to understand in the explanation.

The ON / OFF signal of the switching element Y is generated by advancing the phase angle of the modulated wave M0 of FIG. 3 by 120 degrees and comparing the amplitudes of the modulated wave M0 and the carrier wave C0. The ON / OFF signal of the switching element Y bar is obtained by inverting that of the switching element Y. The ON / OFF signal of the switching element Z is generated by delaying the phase angle of the modulated wave M0 of FIG. 3 by 120 degrees and comparing the amplitudes of the modulated wave M0 and the carrier wave C0. Switching element Z bar ON
The / OFF signal is obtained by inverting that of the switching element Z.

When this ON / OFF signal (switching signal) is supplied to the inverter circuit 40, its ON / O
DC power is turned on / off by the switching elements X, X bar, Y, Y bar, Z, Z bar in the same pattern as the duty ratio of the FF signal, and a pseudo sine wave is generated. Since the period of the modulated wave M0 corresponds to the frequency F of the pseudo sine wave,
By changing the period of the modulated wave M0, the frequency F of the pseudo sine wave is changed.
Can be changed. If the cycle of the carrier wave C0 is reduced, the number of times the pseudo sine wave is turned on / off in one cycle is increased, so that the resolution of the pseudo sine wave is improved. In Figure 3,
For the sake of explanation, the frequency of the carrier wave is shown largely.

FIG. 4 shows ON when the amplitude of the modulated wave is changed.
The change of the / OFF signal is shown. When the amplitude of the modulation wave increases and changes from M0 to M1, the pseudo sine wave also changes from S0 to S1, and a pseudo voltage (calculated on both ends of the exciting coil when a pseudo sine current flows in the induction motor) is calculated. Terminal voltage) becomes high. The difference between the maximum ON time and the minimum ON time becomes large, and this pseudo voltage becomes high. Also, when the amplitude of the modulated wave becomes small and changes from M0 to M2, the pseudo sine wave becomes S
The state becomes 2, and the pseudo voltage becomes low.

Therefore, the three-phase AC voltage supplied to the induction motor 1 can be changed by changing the amplitude of the modulated wave, and the three-phase AC frequency can be changed by changing the frequency of the modulated wave.

FIG. 5 is a block circuit diagram of a main part of the microprocessor 39 for generating an ON / OFF signal (switching signal). In the figure, reference numeral 60 is 16 bi
t / UP / DOWN counter. This counter 60
Count value is added in synchronization with the clock, and when the count value reaches FFFFH, the count value is subtracted in synchronization with the clock. And subtraction are repeated. Therefore, the output (count value) of the counter 60 changes like a triangular wave (carrier wave).

Reference numeral 61 is a sine wave control unit, which receives a frequency command value f for commanding the frequency F and a voltage command value v for commanding the voltage V (pseudo voltage), and stores the sine wave in the storage area. Formed by data change of FFFFH. The formation of this sine wave is performed based on the flowchart shown in FIG. First, in step S11, initialization of f and v is performed (f = 0, v = 0.80). For the sake of explanation, f is f = 0 and 10 ≦ f ≦ 150 Hz,
Although 0.50 ≦ v ≦ 1.00, it is not limited to this.

When it is determined in step S12 that the frequency command value f or the voltage command value v is changed, the process proceeds to step S13, and the sine wave data in the storage area is rewritten. At this time, the sine wave data is corrected by previously multiplying the sine wave data by the value of v. Sine waves 84 to 86 in FIG. 7 represent sine wave data in the storage area. The sine wave 84 is f = 10, v =
It is a fundamental wave of 1.00, and the value changes and is stored as shown in the figure between addresses C0 to C10. Sine wave 8
5 is sine wave data when f = 10 and v = 0.66, and sine wave 86 is sine wave data when f = 20 and v = 1.00. The values of C10 and C20 are determined by the frequency of the clock used. For example, when a clock of 100 KHz is used, C10 = 10000, C20 = 5000
Becomes

Sine waves (1/2 cycle) 80, 82, 83
Is the value of the sine wave data stored in the storage unit 62 (0H to F
FFFH). 0.1 is stored in the storage unit 62.
Sine wave data is stored in units of Hz. f10,
f15 and f20 respectively indicate the start of the sine wave data. The amplitude of these sine wave data increases as the frequency increases. That is, v / f is set to be constant with respect to a preset load.

For example, the value of the sine wave 84 = FFFFH / 2
± (value of sine wave 80) / 2, value of sine wave 85 = F
FFFH / 2 ± 0.66 × (value of sine wave 80) / 2. Other sine waves can be similarly obtained. That is, if the frequency command value f and the voltage command value v are obtained, the sine wave data in the storage area can be rewritten in step S13 of FIG.

In FIG. 6, the sine waves 80, 82, and 83 are shown for 1/2 cycle for ease of explanation, but it may be set for 1/4 cycle to reduce the occupation ratio of the storage section. Needless to say.

Reference numeral 63 in FIG. 5 indicates a sine wave value distributor, which generates values having a phase shift of 120 degrees. For example, f = 10, v = 1.00 (sine wave 84 shown in FIG. 7)
In the case of, the length of one cycle is 0 to C10 (10000). Position 120 degrees out of phase is 0, C10 / 3 = 33
33, the step position of C10 × 2/3 = 6666.

Therefore, assuming that the basic counter is C (driven by a clock), CX = C (0≤C≤C10 = 100
00, C = C10 + 1, C = 0), CY = C
X + C10 / 3 (when CY> C10 = 10000, CY
= CX + C10 / 3-C10 = CX + 3333-100
00), CZ = CX + C10 × 2/3 (CZ> C10 =
When 10000, CZ = CX + C10 × 2 / 3−C10
= CX + 6666-10000).

The sine wave values corresponding to the counter values CX, CY, CZ correspond to the sine wave 84 values shown in FIG. Therefore, changes in the value of the sine wave when the value of the counter C is changed are as shown by the waveforms 64, 65, and 66 in FIG. The waveforms 64-66 are 120 degrees out of phase.

Although the sine waves 84 to 86 in FIG. 7 are shown for one cycle for the sake of easy explanation, it is also possible to reduce the occupancy rate of the storage unit to 1/4 cycle.

In this way, if the frequency command value f and the voltage command value v are given, it is possible to obtain the values of three-phase sine waves in which the phases are shifted by 120 degrees at the frequency F and the voltage V.

In FIG. 5, reference numerals 67 to 69 denote comparators for comparing the magnitude of values. This comparator 67-69 is U
The value of the triangular wave (carrier wave) supplied from the P / DOWN counter 60 and the sine wave (modulation wave) represented by the waveforms 64 to 66.
Compared with the value of, the output is ON (H level voltage) when the value of the modulated wave is larger than the value of the carrier wave. The outputs of the comparators 67 to 69 are supplied as switching signals (ON / OFF signals) of the switching elements X, Y, Z shown in FIG. 2, respectively.

Further, reference numerals 70 to 72 in FIG. 5 denote inverting circuits, which invert the ON / OFF outputs from the comparators 67 to 69 to output switching signals (ON / OFF signals) for the switching elements X bar, Y bar and Z bar. )become.

The switching elements X to Z, X bar to Z
If the delay time for turning the bar ON / OFF (especially ON → OFF) is long, the switching element is turned ON / OFF.
Delay circuit in the circuit that supplies the signal (the signal goes from OFF to ON)
A circuit for delaying this change for a predetermined time) is inserted.

The value given to the comparators 67 to 69 is D / A.
It is also possible to convert the analog voltage level to an analog voltage level and use a comparator for comparing the magnitude of the analog voltage.

In this way, when the frequency command value f and the voltage command value v (in the range of 1.00 to 0.50) are commanded to the sine wave control unit 61 of the microprocessor 39, desired values corresponding to the command values f and v are obtained. AC power of frequency F and amplitude (voltage) V of is obtained.

FIG. 8 shows a control for finely adjusting the index F0 (here, the ratio "V / F" of the voltage V and the frequency F) in accordance with the load state, which is processed by the microprocessor 39. The frequency command value f is determined by the indoor control unit 37 of the indoor unit 370 according to the load and transmitted to the microprocessor 39.

First, in step S21, the microprocessor 39 is initialized and the index F0 = V /
The voltage command value v is initialized so that F = 60.
The value of this index F0 = V / F = 60 is a value set so that the operating efficiency of the compressor is maximized when the compressor is driven at the rated load (constant load that does not fluctuate).

Next, in step S22, the frequency command value f from the indoor unit 370 and various temperatures T (outside air temperature, heat exchanger temperature, etc.) are input.

Then, in step S23, step S2
Other devices are controlled based on the signal input in step 2. For example, switching control of the four-way valve 23, operation of the electric motor 34, defrost control of the outdoor heat exchanger 24, and the like are performed.

Then, in step S24, the C.I. T. The value I of the alternating current detected by 53 is input, and further step S2
In step 5, the outside air temperature T is input again during cooling, and the indoor heat exchanger temperature T is input during heating. The temperature sensor is not shown.

After that, the determinations in steps S26 to S28 are sequentially performed. First, in step S26, the frequency command value f
Is within the predetermined range of the frequency F.
In this embodiment, as the frequency range, as shown in FIG.
= 15 to 80 Hz. Therefore, when the frequency command value f does not fall within the range, the judgment is NO, and when it falls within the range, the judgment is YES and the process proceeds to step S27. The frequency range is not limited to F = 15 to 80 Hz. The reason why the frequency is limited in this way is that the displacement volume of the compressor is large in order to obtain the designed capacity change range. The operating capacity of the compressor is determined by the product of this excluded volume and frequency. If this excluded volume is small, then the frequency will need to be increased to obtain the desired maximum capacity. However, in general, a compressor with a large excluded volume has a problem that the frequency cannot be increased due to its structure.

In step S27, it is determined whether the current value I read in step S24 is less than or equal to the set value. This current setting value is determined according to the frequency F as shown in FIG. 9, and specifically, the low frequency side of 15 Hz ≦ F <50 Hz,
It is determined by a straight line having two different slopes from the high frequency side of 50 Hz ≦ F <80 Hz. For example, when F = 15 Hz, current set value = I15, and when F = 50 Hz, current set value = I50, F = 8
At 0 Hz, the current setting value = I80. In the middle of them, it is a value determined by each straight line. The reason for setting the current setting value in this way is to judge whether the load is high or low with respect to the frequency, that is, its capacity, and this current value is calculated in the calculation when the load is appropriate at that frequency. Is the current value of. The reason why the set value is divided into the low frequency side and the high frequency side of the frequency is that the current at the time of the appropriate load cannot be linearized over the entire area. The frequency-current value data corresponding to the line graph shown in FIG. 9 is stored in the microprocessor 39 as lookup data.

If the current I that is currently supplied is less than or equal to the set value in the determination in step S27, the determination is YES and the process proceeds to step 28.

At step 28, it is judged if the temperature T read at step S25 is less than or equal to a set value. As this set temperature, for example, 36 ° C (outside air temperature) during cooling
However, 46 ° C. (indoor heat exchanger temperature) is adopted during heating, but this value is not necessarily limited. The reason for limiting the temperature in this way is that when the outside air temperature is high, the load becomes large, so it is necessary to increase the voltage, and when the indoor heat exchanger temperature becomes low, the load is large. Is.

If NO in steps S26 to S28, it is judged that the fine adjustment control of F0 (= V / F), which will be described later, is not reached, and the process returns to step S22.

On the other hand, in the microprocessor 39, as shown in FIG.
F0 (= V /
The frequency command value f and the voltage command value v corresponding to F) are supplied to the sine wave control unit 61.

Therefore, in steps S26 to S28, N
In the case of O determination, F0 (= V / F) initialized to 6
The frequency command value f and the voltage command value v corresponding to 0 are supplied to the sine wave control unit 61 in the microprocessor 39. As a result, the sine wave control unit 61 generates an ON / OFF signal for obtaining a three-phase alternating current having a desired frequency and voltage according to the command values f and v. The switching element of the inverter circuit 40 is turned on / off by this ON / OFF signal, and three-phase AC power based on the pseudo sine wave is supplied to the induction motor 1. The frequency F of this three-phase AC power becomes the value commanded by the command value f, and the terminal voltage V of the induction motor 1 also becomes the value commanded by the command value v. As a result, the air conditioner performs the cooling or heating operation instructed by the command values f and v.

On the other hand, when the determination in step S28 is YES, it means that the frequency range, the current, and the temperature all satisfy the preset conditions. In step 39, fine adjustment processing of F0 (= V / F) after step S29 is performed.

In step S29, C.I. T. The current value Inow is input based on the detection signal of 53. Next, in step S30, the voltage command value v is set to be increased so that F0 (= V / F) is increased by 2 steps (the voltage V is decreased). Here, the step width of increasing F0 (= V / F) corresponding to the direction of decreasing the voltage V is not limited to two steps.

When F0 is finely adjusted to decrease the voltage V in this way, the voltage command value v supplied to the sine wave control section 61 decreases (the frequency command value f does not change), and the inverter circuit 40 is correspondingly reduced. The duty ratio of the switching signal supplied changes slightly. As a result, the pseudo voltage supplied to the induction motor is reduced and the slip is finely adjusted, so that the induction motor is controlled so that it can be efficiently operated without changing the frequency according to the light load state.

Next, in step S31, 10 seconds is waited to confirm the current state after raising F0 by two steps.
This waiting time is not limited to 10 seconds. After this waiting, in step S32 the current value Inext at that point is again
C. T. It is read from the detection signal of 53.

Then, in step S33, Inow-Inext
It is determined whether or not ≧ 0. If YES in this determination, F0 is increased by 2 steps (voltage V is decreased) to decrease the current value I, and the process returns to step S22 because energy saving operation is started, and the above-described processing is repeated.

However, F0 is increased by two steps (voltage V
If the answer is NO, then
It can be seen that the control for slightly decreasing the voltage V due to a cause such as shifting to a heavy load is not effective. At this time, in step S34, the voltage command value v is set so as to decrease F0 (= V / F) by 3 steps (increase as the voltage V). The lowering step width is not limited to 3 steps.

By adjusting the step reduction (increasing the voltage V), F0 is 1 compared to before F0 is increased.
The step goes down (voltage V goes up),
F0 is adjusted towards a value corresponding to the increased load.
Then, in step S35, the process waits for 10 seconds to confirm the load trend again, and the process returns to step S22.

By the above processing, when the operating frequency is within the set range, the current of the compressor is below the set value, and the outside air temperature is below the set value, the following conditions are satisfied: The voltage V is finely adjusted while keeping the frequency F of the index F0 (= V / F) constant. As a result, the slippage of the induction motor of the compressor can be changed and the energy-saving operation can be performed while maintaining the same number of revolutions. Therefore, power consumption can be reduced and operation efficiency can be improved. Further, the fine adjustment control does not require a special hardware configuration and the conventional circuit can be used, so that the versatility is high.

FIG. 10 shows comparative data when the fine voltage adjustment control is performed and when it is not performed (however, during the cooling operation). As shown in the figure, when the fine adjustment control is performed (curve indicated by a white circle), compared with the case where it is not (indicated by a black circle), the operating current is remarkably reduced particularly in the frequency range of 15 to 80 Hz. It was

[0066]

As described above, according to the compressor operation control method of the present invention, the predetermined condition when the load is relatively light (the frequency of the alternating current is within the set range, Is less than or equal to a set value and the room temperature when air conditioning is performed by the refrigeration cycle is less than or equal to the set value), the voltage generated in the induction motor is appropriately reduced while keeping the frequency constant. Therefore, the slip of the induction motor is adjusted, the current value is reduced, and the operation becomes highly efficient.

[Brief description of drawings]

FIG. 1 is a block diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a schematic circuit diagram showing an inverter circuit.

FIG. 3 is a diagram illustrating a principle of generating a switching signal.

FIG. 4 is a diagram illustrating changes in the amplitude of a modulated wave and changes in a switching signal.

FIG. 5 is a block diagram showing a switching signal generation circuit unit in the microprocessor.

FIG. 6 is a flowchart showing change settings of a frequency command value f and a voltage command value v.

FIG. 7 is a diagram showing sine wave data in a storage area.

FIG. 8 is a flowchart showing a voltage fine adjustment process performed by a microprocessor.

FIG. 9 is a graph showing a relationship between a frequency setting range and a current setting value.

FIG. 10 is a graph showing a difference in operating current when the voltage fine adjustment control of the present invention is performed and when it is not performed.

[Explanation of reference numerals] 1 induction motor 5 compressor 6 compressor body 24 heat source side heat exchanger 25 to 27 capillary tube 29 use side heat exchanger 39 microprocessor 40 inverter circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Chisunori Isobe 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A compressor that constitutes a refrigeration cycle using a compressor, a condenser, a pressure reducing device, and an evaporator, and that arbitrarily changes the frequency of AC power supplied to an induction motor mounted as a rotation source in the compressor. In the operation control method of No. 1, it is determined whether the load of the refrigeration cycle is within a predetermined range, and when the load satisfies this range, the frequency (F) of the AC power is not changed and the voltage (V) is not changed. A method for controlling the operation of a compressor, which is characterized in that 2. The range is such that the frequency of the AC power is within a set range, the current of the AC power is less than or equal to a set value, and the space temperature when air conditioning a predetermined space is performed by the refrigeration cycle. The operation control method for a compressor according to claim 1, wherein the operation value is equal to or less than a set value.