JP2983809B2 - Compressor operation control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control method for a compressor, 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 on an air conditioner or the like. About.

[0002]

2. Description of the Related Art Conventionally, most compressors mounted on air conditioners 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 number of rotations (capacity) of the compressor is controlled by changing the frequency F of the AC power supplied to the induction motor,
The operation ability according to the load of the refrigeration cycle was obtained. At this time, the voltage V of the AC power (the pseudo voltage generated in the stator winding of the induction motor in the case of using a PWM inverter) is V / F even if the frequency F is adjusted according to the load. Was previously set to be always constant.

In particular, in a PWM type inverter device,
Generally, the ON / OFF pattern of the switching element is 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 on a one-to-one basis, thereby reducing the amount of ROM used.

[0004]

In the above-described conventional operation control method for a compressor, the frequency F is controlled while the V / F ratio is always kept constant. Considering the fluctuation, set the value of V / F higher.
This prevents the compressor from locking when the load increases. Therefore, when the load is light, the operation efficiency is naturally reduced.

[0005] In order to eliminate such a decrease in operating efficiency, a method has been disclosed in which a power factor of AC power supplied to an induction motor is obtained, and a voltage is controlled so that the power factor is maximized (Japanese Patent Application Laid-Open No. Sho. No. 61-20236).

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

That is, when a pseudo sine wave (an AC waveform obtained by switching a DC voltage based on PWM theory) generated by an inverter circuit is supplied to a motor, the pseudo sine wave is generated by the inductance of a stator winding of the motor. Is somewhat smoothed, but distortion still remains in the current waveform, so that the detection accuracy is reduced as described above. This disadvantage is particularly noticeable in the case of a small output motor (several kW or less), in which the waveform distortion rate becomes large, and the above-mentioned disadvantage is remarkable.

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

However, also 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. It is also supposed that the variation in detection is suppressed to some extent by increasing the circuit capability of the detection circuit. However, the detection circuit becomes extremely complicated, and the component cost increases significantly.

The present invention has been made in view of such a conventional problem, and in particular, finely adjusts a voltage V applied to a compressor in accordance with an operation state of an air conditioner while keeping a frequency F thereof constant. It is a main object of the present invention to provide an operation control method capable of increasing the operation efficiency and enabling energy-saving operation.

[0011]

In order to achieve the above object, a method for controlling operation of a compressor according to the present invention comprises a refrigeration cycle using a refrigerant compressor, a condenser, a decompression device, and an evaporator. the frequency and voltage according to the load of the refrigeration cycle to the induction motor incorporated as a rotation drive source of the compressor
Supplies controlled AC power to the operation control of the compressor
In things, the load of the refrigeration cycle is predetermined
Determining whether within a range of load conditions, the load is given
If not, change the frequency and voltage of AC power.
When the load is within the predetermined range,
The voltage of the supplied AC power without changing the frequency of the AC power
It is characterized in that it is controlled to be gradually lowered.

Moreover, the range of the load condition, the refrigerant compressor
The frequency of the AC power supplied to the drive induction motor is within a set range, the current of the AC power is equal to or less than a set value,
In addition, a space temperature when the temperature of the predetermined space is adjusted by the refrigeration cycle is within a range of a set value or less.

[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 equal to or less than the set value, and the room temperature during air conditioning is equal to or less than the set value).
The voltage is appropriately reduced while the frequency F is kept constant. As a result, the slip of the induction motor is adjusted, the current value decreases, and high-efficiency operation is achieved.

[0014]

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 mounted on 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 rotationally drives the compressor body 6.
Consisting of 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 constitute a refrigeration cycle.

When the four-way switching valve 23 is at 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 a cooling operation on the use side, for example, a room. Also, the four-way switching valve 23
Is switched as shown by the dotted line, the compressed refrigerant discharged from the compressor 5 flows in the direction of the dotted arrow, and the use side heat exchanger 29 functions as a condenser this time, and the heat source side heat exchanger 2
Since 4 functions as an evaporator, the indoor heating operation can be performed by the use-side heat exchanger 29.

Reference numerals 31 and 32 in the drawings denote silencers, and 33 denotes a propeller fan for blowing air to the heat source side heat exchanger 24, which is driven by an electric motor 34. Reference numeral 35 denotes a cross flow fan for supplying the conditioned air heat-exchanged (heated / cooled) by the use-side heat exchanger 29 into the room, and is driven by an electric motor 36.

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

The indoor unit 370 outputs to the outdoor unit 371 signals for operating and controlling the devices arranged in the outdoor unit 371, including signals for controlling the frequency F of the AC power supplied to the electric motor 1 of the compressor 5. . The signal from the indoor unit 370 is output to the outdoor unit 371 by
First, it is input via the interface 38 and is 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.
A switching signal for obtaining a pseudo sine wave based on the WM theory is generated. 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-bars, and Z-bars are connected in a three-phase bridge shape, and DC power is supplied to a P terminal in the figure. As the six power switching elements, a power transistor, a power FET, an IWGT, or the like can be used. These six switching elements are turned on / off in response to the switching signal, and generate a three-phase pseudo sine wave in the electric motor 1.
To supply.

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

FIG. 3 is a principle diagram showing generation of a switching signal by the microprocessor 39, and exemplifies a 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 bar is obtained by inverting the ON / OFF signal of the switching element X.

In the upper part of FIG. 3, one waveform C0 indicates a carrier wave (for example, a triangular wave, a stepped triangular wave, a sine wave), and the other waveform M0 indicates a modulated wave (for example, a sine wave, a stepped sine wave). . The ON / OFF signal S0 is determined by the magnitude of the amplitude of the carrier wave C0 and the modulation wave M0, and the modulation wave M0>
In the case of the carrier wave C0, the ON / OFF signal S0 = ON.
Note that the frequencies and frequency ratios of the carrier wave C0 and the modulated wave M0 are not limited to those illustrated, and FIG. 3 shows frequencies that are easy to understand for 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 amplitude of the modulated wave M0 with 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 amplitude of the modulated wave M0 with the carrier wave C0. ON of switching element Z bar
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, the ON / O signal
DC power is turned on / off by 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 modulation wave M0 corresponds to the frequency F of the pseudo sine wave,
By changing the period of the modulation wave M0, the frequency F of the pseudo sine wave is changed.
Can be changed. If the period of the carrier wave C0 is reduced, the number of times of ON / OFF in one period of the pseudo sine wave increases, so that the resolution of the pseudo sine wave is improved. In FIG.
For the sake of explanation, the frequency of the carrier is shown in a large scale.

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

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

FIG. 5 is a block 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
Is to add the count value in synchronization with the clock, and when the count value reaches FFFFH, subtract the count value in synchronization with the clock. And repeat the subtraction. Therefore, the output (count value) of the counter 60 changes in a triangular wave (carrier) shape.

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

When it is determined in step S12 that the frequency command value f or the voltage command value v has been 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 multiplying the sine wave data by the value of v in advance. Sine waves 84 to 86 in FIG. 7 indicate sine wave data in the storage area. The sine wave 84 has f = 10, v =
This is a fundamental wave of 1.00, and its value is changed and stored between addresses C0 to C10 as shown in the figure. 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 and C20 = 5000
Becomes

Sine waves (1/2 cycle) 80, 82, 83
Are the values of the sine wave data stored in the storage unit 62 (0H to F
FFFH). 0.1 is stored in the storage unit 62.
The sine wave data is stored in units of Hz. f10,
f15 and f20 each indicate the start of sine wave data. The amplitude of the 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. Similarly, other sine waves can be 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 in FIG.

In FIG. 7 , the sine waves 80, 82, and 83 are shown for 1/2 cycle for ease of explanation, but may be made for 1/4 cycle to reduce the occupancy of the storage unit. Needless to say.

Reference numeral 63 in FIG. 5 denotes a distributor for sine wave values, which generates values that are shifted in phase by 120 degrees. For example, f = 10, v = 1.00 (sine wave 84 shown in FIG. 7)
In this case, the length of one cycle is 0 to C10 (10000). The position shifted by 120 degrees phase is 0, C10 / 3 = 33
33, C10 × 2/3 = 6666 step position.

Therefore, if 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 it is 10,000, CZ = CX + C10 × 2 / 3-C10
= CX + 6666-10000).

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

Although the sine waves 84 to 86 in FIG. 7 are shown for one cycle for ease of explanation, the sine waves 84 to 86 can be reduced to １ ／ cycle to reduce the occupancy of the storage unit.

In this way, if the frequency command value f and the voltage command value v are given, a three-phase sine wave value whose phase is shifted by 120 degrees between the frequency F and the voltage V can be obtained.

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

Further, reference numerals 70 to 72 in FIG. 5 denote inverting circuits, which invert the ON / OFF outputs from the comparators 67 to 69, and switch signals (ON / OFF signals) of 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 of bar ON / OFF (especially ON → OFF) is long, the switching element is ON / OFF
A delay circuit (signal goes from OFF to ON) in the circuit that supplies the signal
, A circuit which delays this change for a predetermined time) is inserted.

The value given to the comparators 67 to 69 is D / A
The analog voltage level may be converted to an analog voltage level, and a comparator that compares the magnitude of the analog voltage may be used.

As described above, when the frequency command value f and the voltage command value v (ranging from 1.00 to 0.50) are commanded to the sine wave control unit 61 of the microprocessor 39, the desired values corresponding to the command values f and v are obtained. AC power having the frequency F and the amplitude (voltage) V is obtained.

FIG. 8 shows a control for finely adjusting the index F0 (in this case, representing the ratio “V / F” between the voltage V and the frequency F) according to the load condition, and is processed by the microprocessor 39. The frequency command value f is obtained according to the load by the indoor control unit 37 of the indoor unit 370 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 the index F0 = V / F = 60 is a value set so that the operating efficiency of the compressor is best when the compressor is driven at a rated load (a constant load that does not fluctuate).

Next, the process proceeds to step S22, where a frequency command value f from the indoor unit 370, various temperatures T (outside air temperature, heat exchanger temperature, etc.) are input.

Next, in step S23, step S2
The other devices are controlled based on the signal input in step 2 and the like. 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.

Next, at step S24, C.I. T. 53 inputs the detected value I of the alternating current,
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 illustration of the temperature sensor is omitted.

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

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

If it is determined in step S27 that the current I being supplied is equal to or less than the set value, the determination is YES, and the process proceeds to step S28.

In step 28, it is determined whether or not the temperature T read in step S25 is lower than a set value. As the set temperature, for example, 36 ° C (outside air temperature) during cooling
However, during heating, 46 ° C. (indoor heat exchanger temperature) is employed, but this is not necessarily limited. The reason for limiting the temperature in this way is that when the outside air temperature is high, the load is large, so the voltage must be increased, and when the indoor heat exchanger temperature is low, the load is large. It is.

If the determination in steps S26 to S28 is NO, it is determined that the control does not reach the fine adjustment control of F0 (= V / F) described later, and the process returns to step S22.

On the other hand, in the microprocessor 39, 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 the determination of O, the initially set F0 (= V / F) = 6
The frequency command value f and the voltage command value v corresponding to 0 are supplied to a sine wave control unit 61 in the microprocessor 39. Thus, the sine wave control unit 61 generates an ON / OFF signal for obtaining a three-phase alternating current of a desired frequency and voltage according to the command values f and v. The switching element of the inverter circuit 40 is turned on and off by the 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 the three-phase AC power is a value specified by the command value f, and the terminal voltage V of the induction motor 1 is also a value specified by the command value v. Thereby, the air conditioner performs the cooling or heating operation instructed by the instruction values f and v.

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

In step S29, C.I. T. The current value Inow is input based on the 53 detection signal. Next, in step S30, a setting is made to change the voltage command value v so as to increase F0 (= V / F) by two steps (decrease as voltage V). 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 in the direction of decreasing the voltage V in this manner, the voltage command value v supplied to the sine wave control unit 61 decreases (the frequency command value f is not changed). The duty ratio of the supplied switching signal slightly changes. As a result, the pseudo voltage supplied to the induction motor is reduced, and the slip is small and finely adjusted. Therefore, the operation is controlled so that the operation can be performed efficiently without changing the frequency corresponding to a light load state.

Next, at step S31, the control waits for 10 seconds to confirm the current state after raising F0 by two steps.
This waiting time is not limited to 10 seconds. After this standby, at step S32, the current value Inext
To C. T. Read from the 53 detection signals.

Then, in step S33, Inow-Next
It is determined whether or not ≧ 0. When the determination is YES, the current value I is decreased by increasing F0 by two steps (the voltage V is decreased), and the process returns to step S22 assuming that the operation is toward the energy-saving operation, and the above-described processing is repeated.

However, F0 was increased by two steps (voltage V
Despite this, if the judgment is NO,
It can be understood that the control for slightly reducing the voltage V is not effective due to a cause such as a shift to a heavy load. In this case, in step S34, setting is made to change the voltage command value v so that F0 (= V / F) is reduced by three steps (increased as voltage V). This lowering step width is not limited to three steps.

By adjusting this step reduction (increase as voltage V), F0 becomes 1 compared to before increasing F0.
The step will drop (increase as voltage V),
F0 is adjusted toward a value corresponding to the increase in load.
Thereafter, in step S35, the process waits for 10 seconds again to confirm the trend of the load, and returns to step S22.

By performing the above processing, the operating frequency is within the set range, the current of the compressor is equal to or lower than the set value, and the outside air temperature during cooling and the temperature of the indoor heat exchanger during heating are controlled.
The temperature of the specified space is controlled by the refrigeration cycle
When the space in which the temperature meets the predetermined condition that the temperature is equal to or lower than the set value, the frequency f within the index F0 (= V / F) is satisfied.
The voltage v is finely adjusted while keeping constant. Thus, the energy-saving operation can be performed while changing the slip of the induction motor of the compressor and maintaining the same rotation speed, so that the power consumption can be reduced and the operation efficiency can be increased. Further, in performing the fine adjustment control, no special hardware configuration is required, and the conventional circuit can be used, so that the versatility is high.

FIG. 10 shows comparison data when the above-mentioned voltage fine 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), the operating current is significantly reduced especially in the frequency range of 15 to 80 Hz, as compared with the case where the fine adjustment control is not performed (shown by a black circle). Was.

[0066]

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

[Brief description of the drawings]

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

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

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

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

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

FIG. 6 is a flowchart showing a change setting 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 illustrating 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 between when the voltage fine adjustment control of the present invention is performed and when it is not performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Induction motor 5 Compressor 6 Compressor main body 24 Heat source side heat exchanger 25-27 Capillary tube 29 User side heat exchanger 39 Microprocessor 40 Inverter circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Tomonori Isobe 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-64-38547 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F24F 11/02 102 F25B 1/00 361

Claims (2)

(57) [Claims] 1. A refrigerant compressor, a condenser, a pressure reducing device, and constitute a refrigeration cycle using an evaporator, driving the rotation of the compressor
The load of the refrigeration cycle to the induction motor which is mounted as a dynamic source
In those corresponding frequency and the operation control voltage is supplied the AC power controlled in pressure <br/> compressor, whether it is in the range of load conditions the load is predetermined in the refrigeration cycle
If the load is not within the specified range, the AC power
Performs control of changing the frequency and voltage, sometimes the load is in a predetermined range <br/> the circumference, without changing the frequency of the AC power
An operation control method for a compressor, characterized in that control is performed such that the voltage of supplied AC power is gradually reduced. 2. The range of the load condition is determined based on the operation of the refrigerant compressor.
The frequency of the AC power supplied to the induction motor is within a set range, the current of the AC power is equal to or less than a set value, and
An operation control method for a compressor, wherein a space temperature when a temperature of a predetermined space is adjusted by the refrigeration cycle is within a set value or less.