KR20200055312A - Air conditioner and operation method thereof - Google Patents

Abstract

The present invention relates to an air conditioner and an operation method thereof to reduce noise. The air conditioner may include a motor, a plurality of switches, a driving unit turning on or off each of the plurality of switches based on a switching frequency, and a control unit controlling the switching frequency differently according to a time zone.

Description

Air conditioner and operation method thereof

The present invention relates to an air conditioner and an operation method thereof, and more particularly, to an air conditioner for reducing noise and an operation method thereof.

Inverters are used to obtain alternating current by interrupting direct current according to the on and off of the switch. Specifically, the inverter is used to drive an electric motor used in a compressor, fan, or the like of an air conditioner, or to drive a motor of an electric vehicle.

On the other hand, the inverter can vary the switching frequency (or carrier frequency) to drive the motor at any speed, and the switch is turned on and off according to the switching frequency. At this time, noise may be generated by switching on and off.

Therefore, a method for solving the noise problem due to the switching frequency may be required, and an example thereof is disclosed in Korean Patent Publication No. 10-2004-0038209A (May 08, 2004).

The noise prevention device according to the preceding patent intends to minimize noise due to the switching frequency by converting the switching frequency to a fan noise frequency of a relatively high energy outdoor fan.

Republic of Korea Patent Publication 10-2014-0040094 A 10-2004-0038209A (published May 8, 2004)

The present invention is to provide an air conditioner and a method of operating the same to reduce noise generated when a plurality of switches for driving a motor are turned on and off, and to minimize heat generation problems caused by a plurality of switches being turned on and off. .

An air conditioner and an operation method thereof according to an embodiment of the present invention minimizes heat generation by lowering switching frequencies controlling a plurality of switches during the daytime, and reducing noise by increasing switching frequencies controlling a plurality of switches during the nighttime. Can be.

In addition, the air conditioner and its operation method according to an embodiment of the present invention can monitor the heat generation amount by sensing the temperature of the PCB while controlling the switching frequency high for noise reduction.

According to an embodiment of the present invention, the switching frequency is lowered during the daytime to minimize heat generation, thereby increasing the efficiency, and at the night time, the switching frequency is higher than the audible frequency to minimize noise, thereby minimizing user inconvenience caused by noise.

In addition, the present invention has the advantage of minimizing damage to the device due to overheating by monitoring the amount of heat generated by a plurality of switches and adjusting the switching frequency.

In addition, by controlling the switching frequency by differentiating between daytime and nighttime, there is no need to provide a separate cooling mechanism for minimizing heat generation, thereby simplifying the structure and reducing manufacturing cost.

1 is a circuit diagram of a power converter of an air conditioner according to an embodiment of the present invention.
2 is a graph showing efficiency according to a switching frequency according to an embodiment of the present invention.
3 is a control block diagram of an air conditioner according to an embodiment of the present invention.
4 is a flowchart illustrating an operation method of an air conditioner according to an embodiment of the present invention.
5 is a flowchart illustrating a method of performing time zone judgment operation according to a first embodiment of the present invention.
6 is a flowchart illustrating a method of performing time zone judgment driving according to a second embodiment of the present invention.
7 is a flowchart illustrating a method of performing time zone judgment driving according to a third embodiment of the present invention.
8 is a spectrum of an audio signal around the air conditioner when the switching frequency is 5 kHz.
9 is a spectrum of audio signals around the air conditioner when the switching frequency is 10 kHz.

Hereinafter, a specific embodiment of the present invention will be described in detail with the accompanying drawings.

1 is a circuit diagram of a power converter of an air conditioner according to an embodiment of the present invention.

The power converter 100 shown in FIG. 1 includes a power input unit 1 that receives external power, a converter 2 that converts an AC voltage input from the outside into a DC voltage, and a DC output from the converter 2 It may include a DC link capacitor (3) for smoothing the voltage, and an inverter (10) for switching the output of the DC link capacitor (3) and supplying it to the load (4).

Meanwhile, the power converter as shown in FIG. 1 is not limited to an air conditioner, and is applicable to electronic devices such as an electric vehicle, and the embodiment of the present invention is not limited to an air conditioner, and a power source such as an electric vehicle It can be applied to all of the electronic devices including the conversion device 100.

The power input unit 1 may receive an external three-phase AC voltage.

The converter 2 may be connected to the power input unit 1 and receive an AC voltage from the power input unit 1 to rectify the DC voltage. Although not illustrated in FIG. 1, the converter 2 may include at least one of a rectifier, a boost converter, and a reactor according to an embodiment.

The DC link capacitor 3 may be connected in parallel between the output terminal of the converter 2 and the input terminal of the inverter 10.

The inverter 10 may have one end connected in parallel to the DC link capacitor 3 and the other end connected to the load 4. Here, the load 4 may include a motor of an air conditioner compressor, a motor of an air conditioner outdoor fan, and the like.

The inverter 10 may convert the DC voltage smoothed from the DC link capacitor 3 into an AC voltage and supply it to the load 4.

The inverter 10 may include a plurality of switches 11 and a driver 12 for turning on and off each of the plurality of switches 11. For example, the inverter 10 may include six switches 11, and the driver 12 may individually control each of the six switches 11 to supply an AC voltage to the load 4.

Meanwhile, the driving unit 12 may turn each of the plurality of switches 11 on or off based on the switching frequency, and the switch 11 may be turned on or off by the control of the driving unit 12.

At this time, high frequency noise may be generated when the switch 11 is turned on / off. In particular, high-frequency noise may occur at a switching frequency and a frequency that is a multiple of the switching frequency (hereinafter, N times frequency).

The human audible frequency is limited from about 16 Hz to about 20 kHz, and the lower the switching frequency, the N times the frequency belonging to the audible frequency increases, and accordingly the noise increases.

Therefore, when the switching frequency is increased, the N times frequency belonging to the audible frequency decreases, thereby reducing high-frequency noise.

However, as the switching frequency is increased, heat is generated in the PCB (not shown), and thus the PCB drive efficiency decreases. In the present invention, the PCB may be a substrate on which at least some or all of the at least one switch 11 and the driver 12 are installed.

2 is a graph showing efficiency according to a switching frequency according to an embodiment of the present invention.

The first graph 201 shown in FIG. 2 shows the efficiency when the switching frequency of the compressor is 5 kHz, and the switching frequency of the outdoor fan is 16 kHz, and the second graph 202 has the switching frequency of the compressor is 7 kHz, outdoor The efficiency when the switching frequency of the fan is 16 kHz, and the third graph 203 shows the efficiency when the switching frequency of the compressor is 7 kHz and the switching frequency of the outdoor fan is 20 kHz.

That is, the first graph 201 is the efficiency when the switching frequency is the lowest, the third graph 203 is the efficiency when the switching frequency is the highest, and the second graph 202 is the efficiency of the first graph 201. It may be intermediate between the case and the case of the third graph 203.

It can be seen through the first to third graphs 201 to 203 shown in FIG. 2 that the lower the switching frequency, the higher the efficiency, and the higher the switching frequency, the lower the efficiency.

That is, as the switching frequency is increased, noise is reduced, but efficiency is lowered, and problems such as damage to the device due to heat generation may occur.

Accordingly, the present invention is to provide a noise reduction device and a noise reduction method for controlling the switching frequency high by using a point that is quieter than the daytime time zone at a night time zone but has a low outside temperature.

3 is a control block diagram of an air conditioner according to an embodiment of the present invention.

The air conditioner includes a plurality of switches 11 connected to a motor, a driving unit 12 for turning on and off each of the plurality of switches 11, a control unit 50 for controlling the driving unit 12, and determining a time zone It may include at least a part or all of the condition determination unit 20 for the, and the PCB temperature sensor 30 for sensing the temperature of the at least one PCB.

Meanwhile, FIG. 3 is only illustratively illustrated for convenience of explanation, and the air conditioner according to an embodiment of the present invention may further include other components or omit some of them in addition to the components illustrated in FIG. 3. .

The condition determining unit 20 may include at least some or all of the optical sensor 21, the outdoor temperature sensor 22, and the time setting unit 23.

The condition determination unit 20 may determine the time zone through at least one of the optical sensor 21, the outdoor temperature sensor 22, and the time setting unit 23. The controller 50 may selectively determine whether the current time is a day time zone or the current time is a night time zone through the condition determining unit 20 to selectively perform the night mode or the day mode.

According to the first embodiment, the control unit 50 may determine the time zone based on the amount of light sensed by the light sensor 21. This will be described later in detail in FIG. 5.

The optical sensor 21 may be installed outside the air conditioner. Preferably, the optical sensor 21 may be installed on the outer surface of the outdoor unit including a motor connected to a plurality of switches (11). The optical sensor 21 may detect the light received from the outside to calculate the amount of light.

According to the second embodiment, the control unit 50 may determine the time zone based on the outside temperature detected by the outside temperature sensor 22. This will be described later in detail in FIG. 6.

The outside temperature sensor 22 may detect the temperature of the outside air. The outdoor temperature sensor 22 may be installed outside the air conditioner, and similarly to the optical sensor 21, it is preferable to be installed on the outer surface of the outdoor unit including a motor connected to a plurality of switches 11. The outside temperature sensor 22 may detect the outside temperature.

According to the third embodiment, the control unit 50 may determine the time zone through the time setting unit 23, which will be described later in detail in FIG. 7.

The time setting unit 23 may include a communication module (not shown) for receiving current time information from an external server, and compare the received current time with a set time range to determine the time zone.

Alternatively, the time setting unit 23 may include an input module (not shown) for receiving current time information from a user, and compare the set time range with the inputted current time to determine the time zone.

Meanwhile, the control unit 50 may determine the time zone by using at least two of the optical sensor 21, the outdoor temperature sensor 22, and the time setting unit 23.

The PCB temperature sensor 30 may be a temperature sensor installed in a PCB (not shown), and the controller 50 may monitor the amount of heat generated in the PCB through the PCP temperature sensor 30.

The control unit 50 may set the switching frequency based on the time zone determined by the condition determining unit 20 or the temperature detected by the PCB temperature sensor 30, and may control the driving unit 12 based on the set frequency. .

4 is a flowchart illustrating an operation method of an air conditioner according to an embodiment of the present invention.

The control unit 50 may perform a time zone judgment operation (S100).

The controller 50 may perform a time zone judgment operation to select one of the night mode and the day mode. The control unit 50 may perform a time zone judgment operation to perform a night mode or a day mode.

Here, the night mode may be an operation mode for minimizing noise generation.

The day mode may be an operation mode for cooling the heated PCB due to heat or high temperature outside air generated during the night mode.

In the example of FIG. 4, the time zone is divided into a day time zone and a night time zone, but this is merely an example for convenience of time. According to an embodiment, the control unit 50 may be divided into two or more time zones, and control the switching frequency differently according to each time zone.

Hereinafter, a method for performing time zone judgment driving will be described in detail.

5 is a flowchart illustrating a method of performing time zone judgment operation according to a first embodiment of the present invention.

The control unit 50 may detect the amount of light through the optical sensor 21 (S111).

The optical sensor 21 can detect the amount of light from the outside. The light sensor 21 may detect the light for a predetermined time to calculate the light amount.

When the light sensor 21 calculates the amount of light, a predetermined time for sensing light may be adjusted. The time zone determination accuracy when the light sensor 21 detects the light for the first time and calculates the light amount is higher than the time zone determination accuracy when the light sensor detects the light for the second time less than the first time and calculates the light amount. Can be. For example, the optical sensor 21 can detect the light for 10 seconds to calculate the amount of light, but this is only an example.

The control unit 50 may compare the sensed light amount of the optical sensor 21 with the reference light amount (S113). The control unit 50 may determine the amount of light sensed by the light sensor 21 to the reference light amount and determine the night time zone or day time zone.

Here, the reference light amount is a preset value. The reference light amount may be set to change according to seasonal changes. The reference light amount may be adjusted together when a predetermined time for the light sensor 21 to sense light is adjusted.

If the amount of light detected from the outside is less than the reference light amount, the controller 50 determines the time zone at night (S115), and if the amount of light sensed from the outside exceeds the reference light amount, the controller 50 may determine the daylight time period (S117).

As described above, since the control unit 50 automatically estimates the time zone through the optical sensor 21, there is an advantage that the user does not need to input the time zone separately.

6 is a flowchart illustrating a method of performing time zone judgment driving according to a second embodiment of the present invention.

The control unit 50 may sense the outside temperature through the outside temperature sensor 22 (S121).

The control unit 50 may compare the outside temperature detected through the outside temperature sensor 22 with the set temperature (S123).

The control unit 50 may determine the night time zone or the daytime zone by comparing the outside temperature detected by the outside temperature sensor 22 with the set temperature.

Here, the set temperature is a preset temperature value, and may be changed and set according to seasonal changes.

If the outside temperature is below the set temperature, the controller 50 may determine the night time zone (S125), and if the outside temperature exceeds the set temperature, the controller 50 may determine the daytime time zone (S127).

As described above, since the control unit 50 automatically estimates the time zone through the outside temperature sensor 22, there is an advantage that the user does not need to input the time zone separately.

In addition, when determining the time zone through the outdoor temperature sensor 22, despite the night time zone, there is an advantage of minimizing the case where the PCB is overheated by controlling the switching frequency high when the outdoor air is relatively high.

7 is a flowchart illustrating a method of performing time zone judgment driving according to a third embodiment of the present invention.

The control unit 50 may receive the current time information through the time setting unit 23 (S131).

The control unit 50 may determine whether the current time received through the time setting unit 23 falls within the set time range (S133).

The control unit 50 may determine the night time zone or day time zone according to whether the current time received through the time setting unit 23 falls within the set time range. In this case, the control unit 50 may set a time range for distinguishing the night time zone from the night time zone in advance.

If the current time received through the time setting unit 23 falls within the set time range, the controller 50 determines the night time zone (S135), and the control unit 50 receives the current time received through the time setting unit 23. If it does not fall within the set time range, it may be determined as a day time period (S137).

For example, the control unit 50 may preset 20: 00: 00-06: 59: 59 as a night time range, and the control unit 50 may set the current time to 20: 00: 00-06: 59: 59. If it belongs, it can be judged by the night time zone, and if the current time does not belong to 20: 00: 00-06: 59: 59, it can be judged by the day time zone. Meanwhile, the control unit 50 may set 20: 00: 00-06: 59: 59 as a night time range and simultaneously set 07: 00: 00-19: 59: 59 as a daytime time range.

As described above, since the control unit 50 automatically estimates the time zone through the time setting unit 23, there is an advantage that the user does not need to input the time zone separately.

In addition, when determining the night time zone and the day time zone through the time setting unit 23, there is an advantage of high accuracy of time zone determination.

Again, FIG. 4 will be described.

The controller 50 may determine whether the time zone is night based on the result of performing the time zone determination operation (S200).

If the controller 50 determines the time zone as a daytime time zone, it may perform a daytime mode (S300).

When the daylight mode is performed, the control unit 50 may set the switching frequency to the first frequency (S400).

The control unit 50 may control the driving unit 12 by setting the switching frequency to the first frequency, and perform the time zone determination operation again. At this time, the control unit 50 may set the switching frequency to the first frequency, and perform a time zone determination operation again after a preset period of time has elapsed. The preset cycle time may be 60 minutes, but this is only exemplary.

Meanwhile, in step S200, if the controller 50 determines the time zone as a night time zone, the night mode may be performed (S500).

When the night mode is performed, the controller 50 may set the switching frequency to a second frequency higher than the switching frequency in the day mode (S600).

That is, the control unit 50 may control the switching frequency to the first frequency when the day mode is executed, and the control unit 50 may set the switching frequency to the second frequency higher than the first frequency when the night mode is performed.

The controller 50 may determine each of the first frequency and the second frequency in advance.

The controller 50 may determine the first frequency and the second frequency such that the quotient of the result of dividing the specific value by the second frequency is less than the quotient of the result of dividing the specific value by the first frequency. At this time, the specific value may be the highest frequency of the audible frequency band.

For example, a specific value may be 20 kHz. For example, when the load 4 is a compressor motor, the first frequency may be 2 kHz to 5 kHz, and the second frequency may be 6 kHz to 12 kHz. In addition, when the load 4 is an indoor / outdoor fan motor, the first frequency may be 5 kHz to 16 kHz, and the second frequency may be 16 kHz to 24 kHz.

Specifically, the quotient of the result obtained by dividing 20 kHz by the first frequency means the number of N times frequencies in the audible frequency range when the switching frequency is the first frequency, and the quotient of the result obtained by dividing 20 kHz by the second frequency is the switching frequency. When it is the second frequency, it may mean the number of N times frequencies belonging to the audible frequency range.

For example, when the first frequency is 5 kHz, the quotient of the result of dividing 20 kHz by the first frequency is 4, and when the switching frequency is the first frequency, the number of N times frequencies in the audible frequency range is equal to 4.

Similarly, when the second frequency is 10 kHz, the quotient of the result of dividing 20 kHz by the second frequency is 2, and when the switching frequency is the second frequency, the number of N times frequencies belonging to the audible frequency range is equal to 2.

Therefore, if the first and second frequencies are determined such that the quotient of the result obtained by dividing 20 kHz by the second frequency is less than the quotient by dividing the 20 kHz by the first frequency, the number of N times frequencies belonging to the audible frequency decreases in the night mode. Therefore, there is an effect of reducing noise.

However, in the night mode, as the switching frequency is increased, the fish ratio may be overheated, so the temperature of the fish ratio can be monitored through the fish temperature sensor 30 to minimize damage caused by overheating.

Specifically, the controller 50 may compare the sensing temperature of the PCB temperature sensor 30 with the reference temperature (S700).

According to an embodiment of the present disclosure, if the sensing temperature of the PCB temperature sensor 30 is equal to or lower than the reference temperature, the controller 50 may return to step S100 to perform the time zone determination operation again.

According to another embodiment, if the sensing temperature of the PCB temperature sensor 30 is equal to or lower than the reference temperature, the controller 50 may return to step S400 to perform the night mode again. In this case, the control unit 50 may continuously monitor the temperature of the PCB temperature sensor 30 while maintaining the switching frequency at the second frequency. Accordingly, even if the time zone is changed from night to daytime, the switching frequency is maintained at the second frequency while the PCB is not overheated, thereby minimizing the occurrence of noise even during the daytime.

Meanwhile, in step S700, the controller 50 may perform step S300 when the detected temperature of the PCB temperature sensor 30 exceeds the reference temperature.

That is, when the sensing temperature of the temperature sensor 30 exceeds the reference temperature, the controller 50 may switch from the night mode to the day mode, and convert the switching frequency from the second frequency to the first frequency.

Accordingly, a high switching frequency prevents overheating of the PCB, and has the advantage of minimizing the possibility of burnout.

On the other hand, when switching from the night mode to the day mode, the control unit 50 may block the execution of the night mode within a set time. Specifically, when the switching frequency is converted from the second frequency to the first frequency based on the temperature of the PCB, the control unit 50 may block the case where the switching frequency is set again in the second time period within a set time. The controller 50 may set the switching frequency to the first frequency based on the temperature of the PCB, and perform the time zone determination operation within the set time to maintain the switching frequency at the first frequency even when it is determined in the second time zone. Here, the setting time may be 60 minutes, but this is only exemplary.

Accordingly, there is an advantage that it is possible to secure the time required for the overheated PCB to be cooled. That is, the control unit 50 minimizes the case in which the switching frequency is set to the second frequency before the heat of the PCB is released after converting the switching frequency from the second frequency to the first frequency to prevent overheating of the PCB. , It has the advantage of effectively minimizing the case where the PCB is overheated.

8 is a spectrum of the audio signal around the air conditioner when the switching frequency is 5 kHz, and FIG. 9 is the spectrum of the audio signal around the air conditioner when the switching frequency is 10 kHz.

Referring to FIG. 8, when the switching frequency is 5 kHz, peak signals appear at about 5 kHz, 10 kHz, and 15 kHz, respectively, within the audible frequency band. Referring to FIG. 9, when the switching frequency is 10 kHz, about 10 kHz within the audible frequency band. It can be seen that the peak signal appears.

Therefore, when the switching frequency is 5 kHz, it can be seen that the area in the spectrum of the audio signal is wider than the area in the spectrum of the audio signal when the switching frequency is 10 kHz. Accordingly, when the switching frequency is 5 kHz, the noise level is 10 kHz. It can be seen that it is larger than the noise level in the case of. As described above, the noise reduction effect can be confirmed by increasing the switching frequency.

If the switching frequency is controlled at high levels without distinction between daytime and nighttime, noise can be reduced all the time, but because the PCB may generate heat and burn out, during the daytime, it is usually switched only at nighttime in consideration of the fact that there are more living noises than at nighttime. By increasing the frequency, there is an advantage of minimizing heat generation problems and securing product reliability.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present invention.

4: Load 11: Switch
12: drive unit 21: optical sensor
22: outdoor temperature sensor 23: time setting unit
30: PCB temperature sensor 50: control unit

Claims (15)

motor;
A plurality of switches connected to the motor;
A driving unit that turns each of the plurality of switches on and off based on a switching frequency; And
An air conditioner comprising a control unit for controlling the switching frequency differently according to the time zone. According to claim 1,
The control unit
An air conditioner performing a day mode in which the switching frequency is set to a first frequency or a night mode in which the switching frequency is set to a second frequency higher than the first frequency. According to claim 2,
The plurality of switches or the drive unit further includes a PCP temperature sensor for sensing the temperature of the installed PCB,
The control unit
During the night mode, the detection temperature of the PCB temperature sensor is the reference An air conditioner that switches from the night mode to the day mode when the temperature is exceeded. According to claim 3,
The control unit
An air conditioner that blocks the execution of the night mode within a set time when the night mode is switched to the day mode based on the detected temperature of the PC temperature sensor. According to claim 1,
The control unit
An air conditioner performing a time zone determination operation to perform a daytime mode in which the switching frequency is set to a first frequency or a night mode in which the switching frequency is set to a second frequency higher than the first frequency. The method of claim 5,
Further comprising a light sensor for detecting the amount of light from the outside,
The control unit
In the case of performing the time zone determination operation, an air conditioner for determining the amount of light sensed by the optical sensor with a reference light amount and determining the night time zone or day time zone. The method of claim 5,
Further comprising an outside temperature sensor for detecting the outside temperature,
The control unit
When performing the time zone determination operation, the air conditioner to determine the night temperature zone or daytime zone by comparing the outside temperature detected by the outside temperature sensor with a set temperature. The method of claim 5,
Further comprising a time setting unit for receiving the current time information,
The control unit
When performing the time zone determination operation, the air conditioner to determine the night time zone or day time zone according to whether the current time according to the time setting unit falls within the set time range. According to claim 2,
The control unit
An air conditioner for determining the first and second frequencies such that a quotient of 20 kHz divided by the second frequency is less than a quotient of 20 kHz divided by the first frequency. In the operating method of the air conditioner, each of the plurality of switches connected to the motor is turned on and off based on the switching frequency,
Performing a time zone judgment operation;
Setting the switching frequency to a first frequency when the first time zone is determined as a result of the time zone determination operation; And
And determining that the switching frequency is a second frequency higher than the first frequency when the second time zone is determined as a result of the operation of the time zone determination operation. The method of claim 10,
Sensing a temperature of a fish ratio installed with a plurality of switches or a driving unit controlling the plurality of switches while setting the switching frequency to the second frequency; And
And when the temperature of the PCB exceeds a reference temperature, setting the switching frequency to the first frequency. The method of claim 11,
And setting the switching frequency to the first frequency based on the temperature of the PCB, and determining the second frequency within the set time, maintaining the switching frequency at the first frequency. How it works. The method of claim 10,
The step of performing the time zone judgment driving is
Comparing an externally sensed light quantity with a reference light quantity;
Determining if the externally detected light amount is less than the reference light amount at a night time period; And
And when the amount of light sensed from the outside exceeds the reference amount of light, determining a daytime period. The method of claim 10,
The step of performing the time zone judgment driving is
Comparing the outside temperature with the set temperature;
Determining the night time zone when the outside temperature is below the set temperature; And
And when the outside temperature exceeds the set temperature, determining a daytime period. The method of claim 10,
And determining the first and second frequencies such that a quotient of the result of dividing 20 kHz by the second frequency is less than a quotient of the result of dividing 20 kHz by the first frequency.

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