KR102186423B1 - Air conditioner and operation method thereof - Google Patents

Abstract

The present invention relates to an air conditioner for reducing noise and an operation method thereof, wherein a motor, a plurality of switches connected to the motor, a driving unit for turning on and off each of a plurality of switches based on a switching frequency, and a switching frequency are different according to a time period. It may include a control unit to control it.

Description

Air conditioner and operation method thereof TECHNICAL FIELD

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

Inverters are used to obtain alternating current by intermittent direct current according to the on/off of a switch, and their application fields are expanding in recent years. Specifically, the inverter is used to drive an electric motor used for a compressor or a fan of an air conditioner, or to drive a motor of an electric vehicle.

Meanwhile, the inverter may vary a switching frequency (or carrier frequency) to operate the motor at an arbitrary speed, and the switch is turned on and off according to the switching frequency. At this time, noise may be generated by turning the switch on or off.

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

The noise prevention device according to the above prior patent attempts to minimize the noise caused by the switching frequency by converting the switching frequency to the fan noise frequency of the outdoor fan with relatively high energy.

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

An object of the present invention is to provide an air conditioner and an operating method thereof that reduces noise generated when a plurality of switches driving a motor are turned on and off, and minimizes a heat generation problem that occurs when a plurality of switches are turned on and off. .

The air conditioner and its operation method according to an embodiment of the present invention minimize heat generation by lowering the switching frequency for controlling a plurality of switches during the daytime period, and increase the switching frequency for controlling the plurality of switches during the night time period to reduce noise. I can.

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

According to an exemplary embodiment of the present invention, there is an advantage of minimizing noise due to noise by minimizing heat generation by lowering the switching frequency during the daytime and minimizing noise by raising the switching frequency above the audible frequency during the night time.

In addition, the present invention has an advantage of minimizing damage to an element 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 discriminating between the daytime and nighttime periods, there is an advantage of simplification of the structure and reduction of manufacturing cost because a separate cooling mechanism to minimize heat generation is not required.

1 is a circuit diagram of a power conversion device for 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 flow chart illustrating a method of operating an air conditioner according to an embodiment of the present invention.
5 is a flowchart illustrating a method of performing a time zone determination operation according to the first embodiment of the present invention.
6 is a flowchart illustrating a method of performing a time zone determination operation according to a second embodiment of the present invention.
7 is a flowchart illustrating a method of performing a time zone determination operation according to a third embodiment of the present invention.
8 is a spectrum of a voice signal around an air conditioner when the switching frequency is 5 kHz.
9 is a spectrum of a voice signal around an air conditioner when the switching frequency is 10 kHz.

Hereinafter, specific embodiments of the present invention will be described in detail together with the drawings.

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

The power conversion device 100 shown in FIG. 1 includes a power input unit 1 receiving 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 conversion device as shown in FIG. 1 is not limited to an air conditioner, and can be applied to an electronic device 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 electronic devices including the conversion device 100.

The power input unit 1 may receive a three-phase AC voltage externally.

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

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, or the like.

The inverter 10 may convert the DC voltage smoothed by 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 driving unit 12 that turns 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 on or off each of the plurality of switches 11 based on the switching frequency, and the switch 11 may be turned on or off by the control of the driving unit 12.

In this case, high-frequency noise may occur 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, referred to as N-times frequency).

The human audible frequency is limited from about 16Hz to about 20kHz, and as the switching frequency is lower, the frequency N times that belongs to the audible frequency increases, thereby increasing the noise.

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

However, as the switching frequency increases, heat is generated in the PCB (not shown), resulting in a problem of lowering the PCB drive efficiency. 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 is the switching frequency of the compressor is 7 kHz, and The efficiency when the fan switching frequency is 16 kHz is shown, 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 between the case and the case of the third graph 203.

From the first to third graphs 201 to 203 illustrated in FIG. 2, it can be seen 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 increases, noise decreases, but efficiency decreases, and problems such as damage to the element due to heat generation may occur.

Accordingly, an object of the present invention is to provide a noise canceling device and a noise canceling method for controlling a switching frequency to a high level by using a point that is quieter than the daytime period but the outside temperature is lower during the night time period.

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

The air conditioner has a plurality of switches 11 connected to the motor, a driving unit 12 that turns on and off each of the plurality of switches 11, a control unit 50 that controls the driving unit 12, and determines a time zone. It may include at least some or all of the condition determination unit 20 for and the PCB temperature sensor 30 for sensing the temperature of at least one PCB.

Meanwhile, FIG. 3 is merely illustrative for convenience of description, and the air conditioner according to an embodiment of the present invention may further include or omit some other components other than the components shown in FIG. 3. .

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

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

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

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

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

The outdoor temperature sensor 22 may detect the temperature of the outside air. The outside 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 outside of the outdoor unit including motors connected to the 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 a time zone through the time setting unit 23, which will be described in detail later in FIG. 7.

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

Alternatively, the time setting unit 23 may include an input module (not shown) that receives current time information from a user, and may determine a time zone by comparing the input current time with a set time range.

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

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

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

4 is a flow chart illustrating a method of operating an air conditioner according to an embodiment of the present invention.

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

The control unit 50 may perform a time zone determination operation in order to select one of a night mode and a day mode. The control unit 50 may perform a time zone determination operation in 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 a PCB heated by heat generated during the night mode or by a high temperature outside air.

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. Depending on the embodiment, the control unit 50 may divide into two or more time zones, and control the switching frequency differently according to the divided time zones.

Hereinafter, a method of performing time zone determination driving will be described in detail.

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

The controller 50 may sense the amount of light through the optical sensor 21 (S111).

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

A predetermined time for sensing light when the optical sensor 21 calculates the amount of light may be adjusted. When the optical sensor 21 detects light for a first time and then calculates the amount of light, the accuracy of determining the time zone when calculating the amount of light after detecting the light for a second time less than the first time is higher than the accuracy of determining the time zone. I can. For example, the optical sensor 21 may detect light for 10 seconds to calculate the amount of light, but this is only exemplary.

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

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

If the amount of light detected from the outside is less than the reference amount of light, the control unit 50 may determine the night time zone (S115), and when the amount of light detected from the outside exceeds the reference amount of light, the control unit 50 may determine the day time zone (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 have to separately input the time zone.

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

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

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

The controller 50 may compare the outside temperature detected by the outside temperature sensor 22 with a set temperature to determine a night time zone or a day time zone.

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

If the outside temperature is less than or equal to the set temperature, the control unit 50 determines the night time zone (S125), and when the outside temperature exceeds the set temperature, the control unit 50 determines 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 separately input the time zone.

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

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

The controller 50 may receive 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 a set time range (S133).

The controller 50 may determine a night time zone or a day time zone according to whether the current time received through the time setting part 23 falls within the set time range. In this case, the controller 50 may preset a time range for distinguishing the night time zone and the day time zone.

If the current time received through the time setting unit 23 falls within the set time range, the control unit 50 determines the night time zone (S135), and the control unit 50 determines the current time received through the time setting unit 23 If it does not fall within this set time range, it may be determined in a weekly time zone (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 determined in the night time zone, and if the current time does not belong to 20:00:00-06:59:59, it can be determined in the daytime time zone. Meanwhile, the controller 50 may set 20:00:00-06:59:59 as the night time range and set 07:00:00-19:59:59 as the 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 separately input the time zone.

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

Again, Fig. 4 will be described.

The control unit 50 may determine whether the time zone is at night based on the result of the time zone determination driving (S200).

If the control unit 50 determines the time zone as the day time zone, the controller 50 may perform the day mode (S300).

When performing the day mode, the controller 50 may set the switching frequency to the first frequency (S400).

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

On the other hand, in step S200, if the control unit 50 determines the time zone as the night time zone, it may perform the night mode (S500).

When performing the night mode, 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 controller 50 may control the switching frequency as the first frequency when the day mode is implemented, and the controller 50 may set the switching frequency to the second frequency higher than the first frequency when the night mode is implemented.

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 a 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. In this case, the specific value may be the highest frequency among the audible frequency bands.

For example, the 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 unit/outdoor unit 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 of dividing 20 kHz by the first frequency means the number of N-fold frequencies belonging to the audible frequency range when the switching frequency is the first frequency, and the quotient of the result of dividing 20 kHz by the second frequency is the switching frequency. In the case of the second frequency, it may mean the number of N-fold frequencies within 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-fold 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-fold frequencies belonging to the audible frequency range is equal to 2, respectively.

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

However, since the PCB may overheat as the switching frequency is increased in the night mode, the temperature of the PCB may be monitored through the PCB temperature sensor 30 to minimize the problem of damage due to overheating.

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

According to an embodiment, when the temperature detected by the PCB temperature sensor 30 is less than or equal to the reference temperature, the controller 50 may return to step S100 and perform the time zone determination operation again.

According to another embodiment, if the temperature detected by the PCB temperature sensor 30 is less than or equal to the reference temperature, the controller 50 may return to step S400 and perform the night mode again. In this case, the controller 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, there is an advantage of minimizing the generation of noise even in the daytime by maintaining the switching frequency at the second frequency while the PCB is not overheated.

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

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

Accordingly, there is an advantage in that the switching frequency is high, so that overheating of the PCB can be prevented and the possibility of burnout of the PCB can be minimized.

Meanwhile, 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 controller 50 may block a case in which the switching frequency is again set to the second time zone within a set time. The control unit 50 may set the switching frequency to the first frequency based on the temperature of the PCB, and then perform a time zone determination operation within a set time, and maintain the switching frequency as the first frequency even when it is determined as the second time zone. Here, the setting time may be 60 minutes, but this is only exemplary.

Accordingly, there is an advantage of securing a time required for cooling the overheated PCB. That is, the control unit 50 converts the switching frequency from the second frequency to the first frequency to prevent overheating of the PCB, and then minimizes the case where the switching frequency is set to the second frequency before the heat of the PCB is released. , There is an advantage of effectively minimizing the case of overheating the PCB.

8 is a spectrum of a voice signal around the air conditioner when the switching frequency is 5 kHz, and FIG. 9 is a spectrum of a voice 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 each of about 5 kHz, 10 kHz, and 15 kHz within the audible frequency band, and referring to FIG. 9, when the switching frequency is 10 kHz, about 10 kHz within the audible frequency band. It can be seen that a peak signal appears at.

Therefore, when the switching frequency is 5 kHz, the area within the spectrum of the audio signal is larger than the area within the spectrum of the audio signal when the switching frequency is 10 kHz. Accordingly, the noise level when the switching frequency is 5 kHz is 10 kHz. It can be seen that it is larger than the noise level of the case. In this way, the noise reduction effect can be confirmed by increasing the switching frequency.

If the switching frequency is controlled high without distinction between daytime and nighttime, noise can always be reduced, but because PCB can be burned out due to heat generation, switching only during nighttime, taking into account that there is generally more noise in life than nighttime during daytime. 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 will be able to make various modifications and variations without departing from the essential characteristics of the present invention.

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

The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

4: load 11: switch
12: driving unit 21: optical sensor
22: outside 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 on and off each of the plurality of switches based on a switching frequency;
A PCB temperature sensor for sensing the temperature of the PCB in which the plurality of switches or the driving unit are installed; And
It includes a control unit for differently controlling the switching frequency according to the time zone,
The control unit
Performing a day mode in which the switching frequency is set as a first frequency or a night mode in which the switching frequency is set as a second frequency higher than the first frequency,
When switching from the night mode to the day mode based on the detected temperature of the PCB temperature sensor, the execution of the night mode is blocked within a set time,
An air conditioner configured to determine the first and second frequencies such that a quotient of a result of dividing 20 kHz by the second frequency is less than a quotient of a result of dividing 20 kHz by the first frequency. delete The method of claim 1,
The control unit
During the night mode, the temperature detected by the PCB temperature sensor is When the temperature is exceeded, the air conditioner switches from the night mode to the day mode. delete The method of claim 1,
The control unit
An air conditioner for performing a time zone determination operation to perform 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. The method of claim 5,
Further comprising an optical sensor for detecting the amount of light from the outside,
The control unit
When the time zone determination operation is performed, an air conditioner that compares the amount of light detected by the optical sensor with a reference amount of light to determine a night time zone or a day time zone. The method of claim 5,
Further comprising an outside temperature sensor for sensing the outside temperature,
The control unit
When performing the time zone determination operation, an air conditioner that compares the outside temperature detected by the outside temperature sensor with a set temperature to determine the night time or daytime time zone. The method of claim 5,
Further comprising a time setting unit for receiving the current time information,
The control unit
When the time zone determination operation is performed, the air conditioner determines a night time zone or a day time zone according to whether a current time according to the time setting unit falls within a set time range. delete In the operating method of an air conditioner in which each of a plurality of switches connected to a motor is turned on and off based on a switching frequency,
Performing a time zone determination operation;
Setting the switching frequency to a first frequency when it is determined as a first time zone as a result of performing the time zone determination operation;
Setting the switching frequency to a second frequency higher than the first frequency if it is determined as a second time zone as a result of performing the time zone determination operation;
Sensing a temperature of a PCB in which the plurality of switches or a driving unit controlling the plurality of switches is installed while setting the switching frequency to the second frequency;
Setting the switching frequency to the first frequency when the temperature of the PCB exceeds a reference temperature;
Maintaining the switching frequency as the first frequency when it is determined as the second time zone within a set time after setting the switching frequency as the first frequency based on the temperature of the PCB; And
And determining the first and second frequencies such that a quotient of a result of dividing 20 kHz by the second frequency is less than a quotient of a result of dividing 20 kHz by the first frequency. delete delete The method of claim 10,
The step of performing the time zone determination operation
Comparing the amount of light detected from the outside with a reference amount of light;
Determining a night time zone if the amount of light detected from the outside is less than the reference amount of light; And
When the amount of light detected from the outside exceeds the reference amount of light, determining a day time period. The method of claim 10,
The step of performing the time zone determination operation
Comparing the outside temperature and the set temperature;
Determining a night time zone when the outside temperature is below the set temperature; And
The method of operating an air conditioner further comprising determining a weekly time zone when the outside temperature exceeds the set temperature. delete

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