JP2013185778A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein desynchronization often occurs in a low speed region in a motor driving device on which, for example, an one-piston rotary compressor having wide fluctuation of load torque in one rotation is put as a load, and the problem of degradation of indoor comfort due to increase of thermo-off when a minimum rotational frequency is increased to prevent desynchronization.SOLUTION: An air conditioner includes a compressor motor driving a compressor on the basis of a command rotational frequency, a command rotational frequency creating means for creating the command rotational frequency, a command rotational frequency correcting means for applying the command rotational frequency as a first rotational frequency when the command rotational frequency is the first rotational frequency or less, a load detecting means for detecting load of a compressor motor, and a correcting means for making the first rotational frequency variable due to the load of the compressor motor detected by the load detecting means.

Description

  The present invention relates to an air conditioner.

  When a rotation command is input to the brushless motor drive device, the brushless motor rotates in accordance with the rotation command. However, when an overload occurs or when the rotational speed is changed rapidly, the motor does not rotate in response to the rotation command, and a step-out occurs.

  Patent Document 1 discloses a technique for adding a corrected rotational speed to a target rotational speed when a torque command amount for realizing the target acceleration and a discharge pressure value exceed a certain value. According to Patent Document 1, since the minimum number of revolutions can be increased before the load increases, motor step-out can be prevented.

  It is a block diagram which shows the control apparatus of the air conditioner which concerns on the technique of patent document 2. FIG. Patent Document 2 discloses a technique for increasing the minimum number of rotations of the compressor motor when the humidity detected by the humidity detecting means is high and decreasing the humidity when the humidity is low. According to Patent Document 2, even when the room temperature detected by the room temperature detection unit approaches the temperature set by the room temperature setting unit, it is possible to suppress a decrease in dehumidification capability.

JP 2010-98871 A JP 2003-65587 A

  However, although the motor drive device of Patent Document 1 can prevent the step-out, the target rotation speed is increased even when the rotation speed does not need to be increased. "Thermo-off") increases the number of times, and comfort is impaired.

  Moreover, the air conditioner of patent document 2 steps out at the time of the low-speed rotation of an overload state, or peak current increases as a result of performing torque control, and an overcurrent stops. Further, when the minimum number of rotations is increased so as not to step out, the thermo-off increases and the comfort is impaired.

  An object of the present invention is to provide an air conditioner that prevents motor step-out in a low speed region and reduces thermo-off.

  In order to solve the above problems, an air conditioner of the present invention has a compressor motor that drives a compressor based on a command rotational speed, command rotational speed generation means that generates the command rotational speed, and the command rotational speed is the first. Command rotation speed correction means for setting the command rotation speed to the first rotation speed when the rotation speed is equal to or lower than the load speed, load detection means for detecting the load of the compressor motor, and load of the compressor motor detected by the load detection means And a correcting means for varying the first rotational speed.

  ADVANTAGE OF THE INVENTION According to this invention, the air conditioner which prevents the step-out of a motor in a low speed area | region, and reduces thermo-off can be provided.

The air conditioner in Example 1 of this invention. The control block diagram of the air conditioner in Example 1 of this invention. The time chart of the rotation speed control in conventional control. The time chart of the rotation speed control in Example 1 of this invention. The control block diagram of the air conditioner in Example 2 of this invention.

  In the embodiment, a permanent magnet type synchronous motor (hereinafter referred to as “PM motor”) is described as a DC brushless motor. However, the present invention is similarly applied to other synchronous motors such as a wound type synchronous motor and a reluctance motor. be able to.

  Further, the description will be made using a one-piston rotary compressor having a large load torque fluctuation generated during one rotation, but the present invention can be similarly applied to other compressors in which a torque fluctuation occurs during one rotation.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram illustrating the control device of the air conditioner 100 according to the first embodiment of the present invention. The rotation speed command generation means 3 generates the command rotation speed of the compressor motor 9 from the difference between the room temperature detected by the room temperature detection means 1 and the set temperature set by the room temperature setting means 2. The inverter control means 7 outputs a signal to the inverter 8, and the inverter 8 drives the compressor motor 9.

  As shown in FIG. 1, the air conditioner 100 includes an outdoor unit 101 and an indoor unit 102. The refrigeration cycle of the air conditioner 100 includes a compressor 104, a four-way valve, an outdoor heat exchanger 105, an electric expansion valve, and indoor heat. An exchange 106 is provided, and these components are connected by a pipe 103 in this order. The operation of the refrigeration cycle during the cooling operation will be described. The high-temperature and high-pressure gas refrigerant compressed by the compressor 104 flows into the outdoor heat exchanger 105 through the four-way valve switched to the cooling operation side, and releases heat to the outside air by the outdoor heat exchanger 105. It condenses into a high-pressure liquid refrigerant. This refrigerant is reduced in pressure by passing through the electric expansion valve, becomes a low-temperature and low-pressure refrigerant, and flows into the indoor heat exchanger 106. In the indoor heat exchanger 106, air in the room to be cooled or dehumidified is sent to the indoor heat exchanger 106 by the blower 107, and heat is exchanged with the refrigerant, whereby cold air can be sent indoors.

  Also, if the refrigerant temperature is higher than the dew point of the inflowing air, the inflowing air is cooled, and if the refrigerant temperature is lower than the dew point of the inflowing air, the water in the inflowing air is liquefied and drained to the outside as drain water. Air can be sent indoors.

  Further, when the command rotational speed is equal to or lower than the first rotational speed, the command rotational speed is replaced with the first rotational speed.

  Here, the relationship between the room temperature and the set temperature, the command rotation speed, and the load of the compressor motor 9 during the cooling operation in the conventional control will be described with reference to FIG. When the difference between the room temperature and the set temperature is large, the command rotational speed is large, and when the difference is small, the command rotational speed is small. When the rotation speed calculated by the rotation speed command generation means is smaller than the first rotation speed, the compressor 104 is operated by replacing it with the first rotation speed. By setting the first rotation speed to a value that the compressor motor 9 does not step out, step-out can be prevented.

  Furthermore, the load of the compressor motor 9 is detected by the load detection means 5. Then, the correction means 6 changes the first rotational speed 4 based on the load of the compressor motor 9 and transmits it to the inverter control means 7.

  However, in the conventional control shown in FIG. 3, the first rotational speed 4 does not change according to the load. On the other hand, as the load on the compressor motor 9 is smaller, the lower limit value of the rotational speed at which the motor does not step out is lower. Therefore, in the conventional control shown in FIG. 3, even when the load on the compressor motor 9 is small and the rotation speed calculated by the rotation speed command generation means does not need to be replaced with the first rotation speed 4, Therefore, the number of thermo-offs is increased.

  Next, the relationship between the room temperature and the set temperature, the command rotational speed, and the load on the compressor motor 9 during the cooling operation in the control of the present invention will be described using FIG. As the load on the compressor motor 9 detected by the load detecting means is lighter, the first rotational speed 4 is lowered. While the load of the compressor motor 9 is heavy, the first rotational speed 4 is increased so as not to step out. The operation of the air conditioner 100 while the room temperature is away from the set temperature is the same as the conventional control shown in FIG. 3, but does not step out when the rotation speed is lowered when the room temperature and the set temperature are close. Maintain operation at speed. When the load becomes lighter, the first rotational speed 4 is lowered to widen the operating range of the compressor 104 so that a lower ability can be produced. Accordingly, the room temperature detecting means 1 for detecting the room temperature and the room temperature setting means 2 for setting the set temperature are provided, and by detecting the load of the compressor motor 9 based on the difference between the set temperature and the room temperature, It is possible to reduce the thermo-off and realize a more comfortable air conditioner 100.

  In general, when the rotation speed of a brushless motor for driving a compressor or an induction motor is controlled by an inverter, there is a minimum rotation speed at which lubricating oil of the compression mechanism can be supplied to the sliding portion.

  Therefore, there is always a minimum number of revolutions even if the number of revolutions can be controlled steplessly from 0 by an inverter. When the compressor 104 is a scroll compressor, the back pressure is controlled by supplying lubricating oil containing a refrigerant to the back pressure chamber. Therefore, a predetermined amount of lubricating oil must be supplied to the scroll compressor in order to control the back pressure, and there is a minimum number of revolutions. The present invention has a minimum rotation speed as a value equal to or higher than the rotation speed at which the lubricating oil of the compression mechanism section can be supplied to the sliding portion, and the first rotation speed when the first rotation speed 4 is less than the minimum rotation speed By setting the minimum rotational speed, it is possible to maintain the supply of the lubricating oil of the compression mechanism portion to the sliding portion.

  Further, when the room temperature reaches near the set temperature and the room temperature is maintained near the set temperature, the operation at the first rotational speed 4 and the thermo-off are repeated. When performing an operation that repeats thermo-off, the load on the compressor motor 9 is low. Therefore, after the thermo-off is performed once, the first rotation speed 4 may be set as the minimum rotation speed. The thermo-off can be reduced by lowering the first rotational speed 4 to the minimum rotational speed. By reducing the thermo-off, it becomes easier to maintain the room temperature near the set temperature, and it is possible to contribute to the reduction of power consumption.

  Note that when the load detected by the load detection unit 5 is light, the correction unit 6 may decrease the first rotational speed 4. By reducing the minimum speed only when the load is light, the thermo-off is reduced and the comfort in the room can be maintained without sacrificing stability.

  Further, when the load detected by the load detection means 5 is heavy, the correction means 6 may increase the first rotational speed 4. The comfort in the room can be kept as much as possible by making the operation with an emphasis on stability only when the load is heavy.

  The first rotational speed 4 is changed in any one of the operation modes such as the cooling mode, the heating mode, and the dehumidifying mode. Since the relationship between the load weight of the compressor motor 9 and the rotational speed varies depending on each operation mode, the comfort in the room can be further increased by changing the first rotational speed 4 according to the operation mode.

  In addition, an outdoor microcomputer located outside the room is provided, and the outdoor microcomputer includes a first rotation speed, a minimum rotation speed, and correction means 6. The first rotational speed 4 is provided in the indoor microcomputer, and the minimum rotational speed correction limit and the minimum rotational speed correction unit are provided in the outdoor microcomputer. Since the compressor motor 9 in the outdoor unit 101 is controlled by the outdoor microcomputer in the outdoor unit 101, the final minimum rotational speed is determined by the outdoor microcomputer, so that it is not necessary to go through the indoor microcomputer. There is no need to change the software.

  Further, the indoor microcomputer includes the first rotation speed 4 and the minimum rotation speed selection unit. By determining the final minimum number of rotations by the indoor microcomputer, the present invention can be implemented without changing the microcomputer software of the outdoor unit 101.

  As described above, when the compressor motor 9 that drives the compressor 104 based on the command rotational speed, the command rotational speed generation means that generates the command rotational speed, and the command rotational speed is equal to or less than the first rotational speed. The correction means 6 for setting the command rotational speed to the first rotational speed, the load detecting means for detecting the load of the compressor motor 9, and the first rotational speed can be varied by the load of the compressor motor 9 detected by the load detecting means. By providing the correcting means 6 that performs this, it is possible to achieve both prevention of step-out at low speed and reduction of thermo-off.

  The air conditioner 100 includes a torque calculation unit that calculates the torque of the compressor motor 9 and a rotation number detection unit that detects the rotation number as means for detecting the load of the compressor motor 9. The load weight is determined from the rotation speed. The current flowing through the compressor motor 9 increases in proportion to the increase in the load on the compressor motor 9. The torque calculation unit calculates the load of the compressor motor 9 based on the current flowing through the compressor motor 9. Knowing the load weight of the compressor motor 9 accurately makes it possible to determine the load weight more accurately.

  Further, an outside air temperature detecting means for detecting the temperature of the outdoor unit 101 is provided as means for detecting the load of the compressor motor 9, and the weight of the load is determined from the temperature of the indoor unit and the temperature of the outdoor unit 101. In general, the air conditioner 100 includes a room temperature detection unit that detects the room temperature and an outside air temperature detection unit that detects the temperature of the outdoor unit 101. Therefore, the weight of the load can be determined without adding new detection units. .

  Further, when the outdoor temperature is high during cooling and when the outdoor temperature is low during heating, the load on the compressor motor 9 becomes heavy, so the minimum number of revolutions is increased so as not to step out. When the outdoor temperature is low during cooling and when the outdoor temperature is high during heating, the thermo-off can also be reduced by lowering the minimum number of revolutions within a range that does not step out. Accordingly, the outside air temperature detecting means for detecting the outdoor temperature is provided, and the load of the compressor motor 9 is detected based on the outdoor temperature, so that the weight of the load can be determined without increasing new detecting means.

  Further, the load of the compressor motor 9 may be detected based on the difference between the set temperature and the indoor temperature and the outdoor temperature.

  In addition, a discharge temperature detecting means for detecting the discharge temperature of the compressor 104 and a rotation speed detecting section for detecting the rotation speed of the compressor motor 9 are provided, and detected by the discharge temperature and the rotation speed detecting section detected by the discharge temperature detecting means. The weight of the load on the compressor motor 9 is determined from the determined rotation speed. In general, the air conditioner 100 includes discharge temperature detection means for detecting the discharge temperature of the compressor 104 and a rotation speed detection unit for detecting the rotation speed of the compressor motor 9, so that the load can be reduced without increasing new detection means. The weight can be determined.

  Although the case of the cooling operation has been described, the control of the present invention can be similarly applied to the heating operation and the dehumidifying operation.

  Example 2 will be described with reference to FIG. The air conditioner 100 according to the second embodiment includes a first rotation speed 4 and a second rotation speed 10 higher than the first rotation speed 4, and the correction unit 6 is configured such that the load of the compressor motor 9 is equal to or higher than a set value. Uses the first rotational speed as the second rotational speed. When the load of the compressor motor 9 detected by the load detection means 5 is equal to or less than the set value, the first rotation speed 4 is selected, and when the load of the compressor motor 9 is heavy, the second rotation speed 10 is selected. It has a selection means 11 and transmits the minimum number of revolutions to the inverter control means 7. By having the two minimum rotation speeds in advance, the air conditioner 100 that achieves both control stability and indoor comfort can be realized more easily.

  Further, the first rotation speed 4 and the second rotation speed 10 are changed in any one of the operation modes such as the cooling mode, the heating mode, and the dehumidifying mode. Since the relationship between the load weight of the compressor motor 9 and the number of rotations varies depending on each operation mode, indoor comfort can be further increased by changing the first number of rotations 4 according to the operation mode.

  In addition, an outdoor microcomputer located outside the room is provided, and the outdoor microcomputer includes a first rotation speed, a minimum rotation speed, and correction means 6. Further, the first rotation speed 4 is provided in the indoor microcomputer, and the second rotation speed 10 and the minimum rotation speed selection unit are provided in the outdoor microcomputer. Since the compressor motor 9 in the outdoor unit 101 is controlled by the outdoor microcomputer in the outdoor unit 101, the final minimum rotational speed is determined by the outdoor microcomputer, so that it is not necessary to go through the indoor microcomputer. There is no need to change the software.

  The indoor microcomputer includes the first rotation speed 4 or the second rotation speed 10 or both the first and second rotation speeds 10 and the minimum rotation speed selection unit. By determining the final minimum number of rotations by the indoor microcomputer, the present invention can be implemented without changing the microcomputer software of the outdoor unit 101.

  Further, when the room temperature reaches near the set temperature and the room temperature is maintained near the set temperature, the operation at the first rotational speed 4 and the thermo-off are repeated. Once the thermo-off is performed, the thermo-off can be reduced by setting the first rotation speed 4 as the command rotation speed.

  In addition, an outdoor microcomputer located outside the room is provided, and the outdoor microcomputer includes a first rotation speed 4, a second rotation speed 10, and selection means 11. The first rotational speed 4 is provided in the indoor microcomputer, and the minimum rotational speed correction limit and the minimum rotational speed correction unit are provided in the outdoor microcomputer. Since the compressor motor 9 in the outdoor unit 101 is controlled by the outdoor microcomputer in the outdoor unit 101, the final minimum rotational speed is determined by the outdoor microcomputer, so that it is not necessary to go through the indoor microcomputer. There is no need to change the software.

DESCRIPTION OF SYMBOLS 1 Room temperature detection means 2 Room temperature setting means 3 Rotation speed command production | generation means 4 1st rotation speed 5 Load detection means 6 Correction means 7 Inverter control means 8 Inverter 9 Compressor motor 10 2nd rotation speed 11 Selection means 100 Air conditioner DESCRIPTION OF SYMBOLS 101 Outdoor unit 102 Indoor unit 103 Piping 104 Compressor 105 Outdoor heat exchanger 106 Indoor heat exchanger 107 Blower

Claims (11)

A compressor motor that drives the compressor based on the command rotational speed;
Command rotational speed generating means for generating the command rotational speed;
Command rotational speed correction means for setting the command rotational speed to the first rotational speed when the command rotational speed is equal to or lower than the first rotational speed;
Load detecting means for detecting a load of the compressor motor;
An air conditioner comprising: correction means for varying the first rotation speed according to the load of the compressor motor detected by the load detection means.   2. The air conditioner according to claim 1, wherein the correction unit reduces the first rotation speed as the load of the compressor motor detected by the load detection unit is lighter. A second rotational speed higher than the first rotational speed,
The said correction | amendment means makes the said 1st rotation speed the 2nd rotation speed when the load of the said compressor motor detected by the said load detection means is more than a setting value, The said rotation speed is 2nd. Air conditioner. Room temperature setting means for setting the set temperature;
Room temperature detecting means for detecting the room temperature;
An outside air temperature detecting means for detecting the outdoor temperature,
The compressor motor load is detected based on a difference between the set temperature and the indoor temperature, the outdoor temperature, or a difference between the set temperature and the indoor temperature and the outdoor temperature. The air conditioner according to any one of claims 1 to 3.   The air conditioner according to any one of claims 1 to 3, wherein the load detection means detects a load of the compressor motor based on a current flowing through the compressor motor. A discharge temperature detecting means for detecting a discharge temperature of the compressor;
A rotational speed detection means for detecting the rotational speed of the compressor motor,
The air conditioner according to any one of claims 1 to 3, wherein a load of the compressor motor is detected based on the discharge temperature and the rotation speed detected by the rotation speed detection means.   The air conditioner according to any one of claims 1 to 6, wherein when the first rotational speed is equal to or lower than the minimum rotational speed, the first rotational speed is set to the minimum rotational speed.   The air conditioner according to claim 7, wherein the command rotational speed after the thermo-off is performed is the minimum rotational speed.   The air conditioner according to any one of claims 1 to 8, wherein the first rotational speed is different depending on any operation mode such as a cooling mode, a heating mode, and a dehumidifying mode. It has an outdoor microcomputer located outside,
The air conditioner according to any one of claims 1 to 9, wherein the outdoor microcomputer includes the first rotational speed and the correction unit. An outdoor microcomputer located outside the room,
An indoor microcomputer located in the room,
The indoor microcomputer has the first rotational speed;
The air conditioner according to any one of claims 3 to 9, wherein the outdoor microcomputer includes the second rotational speed and the correction unit.