KR20010028947A - Defrost method in inverter air conditioner - Google Patents

Abstract

PURPOSE: A method is provided to achieve an improved efficiency of defrost operation by variably controlling the defrost operation condition in accordance with the defrost operation frequency, the defrost time and the like. CONSTITUTION: A method comprises a first step of determining the defrost operation start time based on the heating operation time and the outdoor pipeline temperature; a second step of converting the cycle by lowering the operation frequency of the compressor upon starting of defrost operation, and performing defrost operation by raising the operation frequency of the compressor; a third step of determining the defrost operation end time based on the defrost time or the outdoor pipeline temperature during the defrost operation; and a fourth step of completely turning off the compressor by gradually lowering the operation frequency of the compressor at the defrost operation end time, and performing cycle conversion operation.

Description

Defrost method in inverter air conditioner {Defrost method in inverter air conditioner}

The present invention relates to a defrosting operation control method of an inverter air conditioner, and more particularly, to a defrosting operation control method of an inverter air conditioner that can perform a more efficient defrosting operation by variably controlling the defrosting operation conditions.

The inverter air conditioner rectifies a constant AC voltage, converts it into direct current, and then converts it into alternating current to control the operation of the compressor. In particular, the capacity of the compressor is changed by changing the frequency or voltage according to the cooling / heating load conditions. That is, the compressor changes the cooling / heating capacity while the rotational speed changes according to the frequency change.

When the inverter air conditioner performs the heating operation, if the outdoor environment is below the freezing point temperature and there is a certain amount of moisture, dew is generated in the outdoor heat exchanger exposed to the outdoor environment while dew is formed. In this state, when the air conditioner continues heating operation, the heat exchange surface of the outdoor heat exchanger freezes, thereby lowering the temperature of the blown air through the indoor heat exchanger, thereby lowering the function of heating. Therefore, the defrosting operation must be performed at regular intervals to remove the icing during the heating operation and to continue the heating operation even in the outdoor environment below the freezing point.

Next, the defrost operation control method of the conventional inverter air conditioner will be described.

1 is a flowchart illustrating a defrosting operation of a conventional inverter air conditioner.

The temperature of the outdoor unit heat exchanger and the outdoor temperature are sensed (S11), and it is determined whether the detected outdoor heat exchanger temperature is less than 3 ° C (S12). When the outdoor heat exchanger temperature is less than 3 ° C., a defrost timer is operated (S13). When the outdoor heat exchanger temperature is 3 ° C. or more, the operation of the defrost timer is cleared (S14).

Then, it is checked whether the outdoor heat exchanger temperature and the outdoor temperature are within the defrosting operation range (S15), and when the state is maintained for 3 minutes (S16), the defrosting operation is performed (S17).

The defrosting operation of the step S17 is performed for 12 minutes, the compressor operation is stopped for about 10 seconds after the defrosting operation is completed (S20, S21).

When the defrosting operation of step S17 is performed, when the set temperature is set to 30 ° C. and the air volume is set to strong wind (S18), the defrosting return temperature is lowered from 14 ° C. to 10 ° C. (S19).

That is, the defrosting operation control method of the conventional inverter air conditioner starts the defrosting operation when the outdoor heat exchanger temperature is less than 3 ° C, the outdoor temperature is within the defrosting operation range, and the condition is maintained for 3 minutes. do. The defrosting operation thus started is completed when the defrosting operation time has elapsed 12 minutes.

Therefore, in the conventional defrosting operation control method, when the outdoor temperature is lowered below a predetermined temperature and continuously meets the defrosting operation start condition, there is a problem that the normal heating operation cannot be performed. In addition, the process of determining the start point of the defrosting operation, performing the defrosting operation, and determining the end point of the defrosting operation by the conventional defrosting operation control method is not appropriate, and thus it is impossible to perform a perfect defrosting operation. This resulted in a problem of lowering the efficiency of the heating operation after completion of the defrosting operation, and also causing frequent defrosting operation, thereby degrading the performance of the system.

Moreover, in the defrosting operation of the conventional inverter air conditioner, there is no method of obtaining more efficient defrosting operation by the variable control of an operation condition.

Accordingly, an object of the present invention is to provide a defrosting operation control method of an inverter air conditioner which can perform a more efficient defrosting operation by judging a current system state and variably controlling defrosting operation conditions according to defrosting operation frequency, defrosting time, and the like. Is in.

1 is an operation flowchart showing a defrosting operation control method of a conventional inverter air conditioner;

2 is a configuration diagram of an inverter air conditioner according to the present invention;

3 is a block diagram of an outdoor unit of an inverter air conditioner according to the present invention;

4 is a timing diagram of a defrosting operation of the inverter air conditioner according to the present invention;

5a to 5g is an operation flowchart for the defrost operation control of the inverter air conditioner according to the present invention.

Explanation of symbols on the main parts of the drawings

10,15: heat exchanger 12: display unit

13,50: microprocessor 20: indoor unit

30: outdoor unit 54, 58: sensor

52: outdoor piping temperature detection unit 56: outdoor temperature detection unit

62: IPM 64: Compressor

66: fan and four sides 68: relay drive unit

70: communication circuit 72: AC power

74: noise filter 76: current transformer

77,78: rectifier circuit 80: output voltage detector

82 DC booster 83 PFC control circuit

84: power factor improvement circuit 60: IPM drive control unit

Defrosting operation control method of the inverter air conditioner according to the present invention for achieving the above object comprises the steps of determining the start time of the defrosting operation based on the re-heating operation time and the outdoor piping temperature; When the defrosting operation is started, the operation frequency of the compressor is lowered to change the cycle, and then the operating frequency of the compressor is increased again to perform the defrosting operation; Determining the end point of the defrosting operation based on the defrosting time or the outdoor pipe temperature during the defrosting operation; At the end of the defrosting operation it is characterized in that it comprises the step of gradually lowering the operating frequency of the compressor to stop completely, and then perform cycle switching.

The defrosting operation start time point of the present invention is characterized in that the re-heating operation time has passed a predetermined time, the outdoor piping temperature is a predetermined temperature or less.

The defrosting operation end point of the present invention is characterized in that the outdoor pipe temperature is raised when the predetermined temperature or more.

The present invention is characterized in that it further comprises the step of controlling the operation is performed within the rated frequency range for a predetermined time after the start of the heating operation.

Hereinafter, an inverter air conditioner according to the present invention will be described in detail with reference to the accompanying drawings.

First, referring to Figure 2 looks at the overall configuration of the inverter air conditioner.

2 is a block diagram of an inverter air conditioner according to the present invention.

The inverter air conditioner is separated into an indoor unit 20 composed of a heat exchanger 10, and an outdoor unit 30 composed of a compressor 64, a heat exchanger 15, and the like. The indoor unit 20 and the outdoor unit 30 have microprocessors 13 and 50 for controlling respective components, and a microprocessor 13 embedded in the indoor unit 20 and a microprocessor embedded in the outdoor unit 30. 50 performs data transmission and reception for control of each other. In addition, the microprocessor 13 of the indoor unit 20 determines the operation state of the current system, and displays the operation of the compressor or the defrost operation by using the LED element. In addition, the outdoor unit 30 includes four sides (not shown) for switching between heating and cooling.

The inverter air conditioner of the above configuration is controlled in the following manner.

First, a user sets a desired operation mode according to cooling / heating operation by using key input means (not shown) provided in the indoor unit 20. Thereafter, when the set temperature for driving the compressor is set in the set operation mode, the set temperature is recognized by the microprocessor 13 inside the indoor unit 20. The microprocessor 13 of the indoor unit 20 transmits the set temperature to the outdoor unit 30 through communication means (not shown).

In addition, the microprocessor 13 of the indoor unit 20 detects a commercial AC voltage input into the air conditioner. The microprocessor 13 sets an operating frequency for driving the compressor 64 according to the sensed AC voltage. The set driving frequency is also transmitted to the outdoor unit 30.

As described above, the indoor unit 20 of the inverter air conditioner enables the user to set a desired operation mode and operation conditions, and simultaneously displays the operation state of the current system on the display unit 12. For example, when the compressor is currently running or defrosting, the LED device emits light to inform the user of this condition.

On the other hand, the microprocessor 50 of the outdoor unit 30 inputs the operation mode and the set temperature, thereby controlling the cooling operation or heating operation accordingly. When the microprocessor 50 performs operation control of the compressor 64 until reaching the set temperature, the microprocessor 50 outputs an on / off signal according to a predetermined operating frequency, and based on the signal, the drive voltage of the compressor 64. Is generated.

Therefore, a high-pressure, high-temperature refrigerant flows through the indoor heat exchanger 10 during the heating operation of the inverter air conditioner, and the refrigerant discharges heat to the air circulating through the heat exchanger 10, thereby discharging warm wind to the indoor side. Is done. And the outdoor side heat exchanger 15 performs the operation opposite to the above operation.

In the cooling operation, a low-temperature, high-pressure refrigerant flows through the indoor heat exchanger 10, and the cool air is discharged to the indoor side by absorbing heat contained in the air circulating through the heat exchanger 10. And the outdoor side heat exchanger 15 performs the operation opposite to the above operation.

The switching of the cooling and heating operation mode of the inverter air conditioner operated as described above is performed by a four-way valve (not shown) that controls the flow of the refrigerant. For example, the outdoor unit microprocessor 50 controls to perform the cooling operation by turning off the operation of the four-way valve, and controls the operation by turning on the operation of the four-way valve during the heating operation.

On the other hand, when the inverter air conditioner performs the heating operation, if the outdoor environment is below the freezing point temperature and there is a certain amount of moisture, dew is formed in the outdoor heat exchanger 15 exposed to the outdoor environment and progresses to freezing. . Therefore, when the air conditioner continues the heating operation, there is a problem that the heat exchange surface of the outdoor heat exchanger 15 is frozen. This freezing lowers the temperature of the blown air through the heat exchanger 10 in the room side, thereby lowering the function of heating. Therefore, it is necessary to perform the defrosting operation at regular intervals in order to remove the freezing and to continue the heating operation even in the outdoor environment below the freezing point.

That is, the defrosting operation means that the cooling operation is performed for a predetermined time in order to thaw the ice covering the heat exchange surface of the outdoor unit 30 in the middle of the heating operation. While the cooling operation is performed, the heat exchanger 15 of the outdoor unit 30 discharges warm wind, and the ice formed to cover the heat exchange surface is thawed by the heat generated at this time.

Next, the control process of the defrosting operation will be described in detail with reference to the outdoor unit of the inverter air conditioner of the present invention.

3 is a detailed configuration diagram of the outdoor unit of the inverter air conditioner according to the present invention.

The outdoor unit of the inverter air conditioner includes a communication circuit 70 for communicating with the indoor unit. The communication circuit 70 is connected to the microprocessor 50 to perform data transmission and reception with an indoor unit. In addition, the outdoor unit of the inverter air conditioner includes a four-direction and outdoor fan 66 for switching between cooling and heating, and a relay driver 68 for controlling the operation of the four-direction and outdoor fan 66. . In addition, the outdoor pipe temperature is detected through the sensor 54, the outdoor pipe temperature sensing unit 52 for converting the detected temperature into an electrical signal and applying it to the microprocessor 50, and the outdoor through the sensor 56 An outdoor temperature detecting unit 56 detects a temperature, converts the detected outdoor temperature into an electrical signal, and applies the detected outdoor temperature to the microprocessor 50.

In addition, the outdoor unit of the inverter air conditioner inputs an AC power source 72 and flows to a noise filter 74 for filtering noise included in the input AC power source and an AC power source applied through the filter 74. A current transformer 76 that detects the total current, senses the current used by the system, and a rectifier circuit 77 that rectifies the output of the current transformer 76 and applies a DC voltage to the microprocessor 50. .

The outdoor unit of the inverter air conditioner includes a rectifying circuit 78 for rectifying the AC power source 72, a power factor improving circuit 84 for improving the power factor from the output of the rectifying circuit 78, and the power factor improving circuit 84. The DC voltage is constant from the output of the PFC control circuit 83 and the power factor improving circuit 84 for controlling the operation of the IGBT element inside the power factor improving circuit 84 so that the phase of the voltage and the current inputted to the same coincide. And a DC boosting unit 82 for boosting the output by a size or more. And an output voltage detector 80 which detects the DC voltage boosted by the DC booster 82 and applies the detected DC voltage to the microprocessor 50.

In addition, the outdoor unit of the inverter air conditioner includes an IPM driver 60 and an IPM 62 for driving the compressor 64 by the output signal of the microprocessor 50. The microprocessor 50 determines the driving voltage of the compressor based on the operating frequency determined by the system input voltage.

That is, the microprocessor 50 generates signals U, V, W, U #, and V # for controlling the operation of the compressor 64 so that a driving voltage of the compressor 64 of a required size can be generated according to the determined operating frequency. , W #) The IPM driving controller 60 outputs a high / low signal for controlling the IGBT element inside the IPM 62 by the output signal of the microprocessor 50. When the IBGT element in the IPM 62 performs the on / off operation by the signal, the DC voltage boosted by the DC boosting unit 82 is converted into a three-phase AC power source to drive the compressor 64. .

Next, the defrosting operation control method in the outdoor unit of the inverter air conditioner having the above configuration will be described.

5 is a flowchart illustrating a method for controlling defrosting of an inverter air conditioner according to the present invention. 4 is an operation timing diagram illustrating the defrosting operation step divided into 0 to 6 steps.

In winter, the inverter air conditioner performs a heating operation to warm the room. At this time, the microprocessor 50 of the outdoor unit receives an operation instruction from the indoor unit 20 side through the communication circuit 72. That is, in addition to the operation frequency of the compressor determined according to the heating operation mode, the AC power input into the system, various information required for performing the heating operation is received from the indoor unit 20 side.

Thereafter, the microprocessor 50 determines voltage / frequency data for driving the compressor according to a predetermined compressor operating frequency, and performs control of the compressor according to the determined data.

Meanwhile, the commercial AC power source 72 input to the outdoor unit is supplied to the rectifier circuit 78, and the rectifier circuit 78 first rectifies the AC power input to the DC voltage. When the DC voltage rectified by the rectifier circuit 78 is applied to the power factor improving circuit 84, the power factor improving circuit 84 is controlled by the PFC control circuit 83 so that the phase of the voltage and current can be matched. Output the input voltage. In this way, the power factor-enhanced voltage is applied to the DC boosting unit 82, and the DC boosting unit 82 continuously charges the input voltage and discharges at a certain point, thereby generating a high power DC voltage.

The generated high-power DC voltage is applied to each IGBT element in the IPM 62, and the IGBT element in the IPM 62 is controlled on / off by a frequency control signal.

That is, the microprocessor 50 outputs the frequency control signals U, V, W, U #, V #, and W # so that a compressor driving voltage having a required magnitude can be generated. The frequency control signals U, V, W, U #, V #, and W # are applied to the IPM driver 60, and the IPM driver 60 is an IGBT element inside the IPM 62 based on the frequency control signal. Outputs a high / low signal for on / off control. In this way, when the on / off operation of the IGBT elements inside the IPM 62 is performed, a high power DC voltage applied to the IGBT element is converted into a three-phase AC power source to drive the compressor 64.

When the compressor 64 starts to be driven in this manner, the refrigerant is circulated through the pipe connecting the indoor unit 20 and the outdoor unit 30. At this time, the high temperature and high pressure refrigerant flows through the heat exchanger 10 on the indoor unit 20 side, and warm wind is discharged to the indoor side by the heat exchange operation of the heat exchanger 10.

In the state in which the heating operation is performed by the operation, the microprocessor 50 performs an operation for determining a time point for starting the defrosting operation.

First, the microprocessor 50 determines whether a key for a current PCB assembly test has been input (step 100). The microprocessor 50 determines whether the indoor unit 20 is in operation (step 103).

When the conditions of steps 100 and 103 are satisfied, it is determined whether the current operation mode is the heating operation mode (step 106).

That is, the processes of steps 100, 103, and 106 are operations for checking whether the current system is performing normal heating operation.

When the heating operation is not performed in step 106, the heating operation timer for counting the heating operation time is turned off, and the flag indicating that the defrosting operation is in progress is also cleared. Then, the value of the step counter for counting the defrosting operation step is also cleared (step 109).

However, if it is determined in step 106 that the heating operation is being performed, the operation of the step counter for counting the defrosting operation step is started (step 112).

When the step 112 is performed, the defrosting operation step is a step ⓞ (step 115).

The defrosting operation? Step is an operation state of the? Step shown in FIG. 4, and is a step for determining a starting point for entering the defrosting operation. That is, the defrosting operation step ⓞ is a state in which the heating operation is being performed. Therefore, the compressor 64 is operated at the heating operation frequency, the four sides and the outdoor fan 66 are on, and the indoor fan (not shown) is operating at the set air volume. At this time, the defrost LED element on the display unit 12 operating under the control of the microprocessor 13 of the indoor unit 20 is in an off state.

During the heating operation by the operation control, the microprocessor 50 compares whether the outdoor piping temperature is greater than T2 ° C (step 118). The outdoor pipe temperature is input to the microprocessor 50 after the temperature detected through the sensor 54 is converted into an electrical signal by the outdoor pipe temperature sensing unit 52. Therefore, the microprocessor 50 detects the outdoor piping temperature based on the input signal.

When the outdoor piping temperature is greater than T2 ° C in step 118, the microprocessor 50 needs to perform the defrosting operation while clearing the defrosting operation flag and also clearing the operation of the step counter that counts the defrosting operation step. It is determined that there is no (step 121).

However, when the outdoor piping temperature is less than T2 ℃ in step 118, the microprocessor 50 compares whether the time to perform the heating operation again after the completion of the defrost has passed t1 (step 124).

When the reheating operation time has not passed t1 in step 124, the microprocessor 50 continues to control the heating operation.

However, when it is determined in step 118 that the outdoor piping temperature is less than T2 ° C. and the reheating operation time elapses in step 124, the microprocessor 50 determines the value of the step count that counts the defrosting operation step. 1 increases. In each defrosting operation stage, the defrosting operation timer that counts the operation time is cleared, and the defrosting operation time is counted. Then, in each defrosting operation step, the defrost second timer that counts the operation time in seconds is cleared (step 127).

By performing step 127, the defrosting operation step becomes step ① (step 130).

Step 1 of the defrosting operation is an operation state of step 1 shown in FIG.

The microprocessor 50 sets the defrosting operation flag. Then, the operating frequency of the compressor 64 is lowered step by step at the set frequency during heating and finally adjusted to a low value by one step at the cooling rated operating frequency Fc. The microprocessor 50 turns off the operation of the indoor fan at about t11 after the start of step 1, and transmits data indicating that the defrosting operation is being performed to the indoor unit 20 through the communication circuit 70. By the data, the microprocessor 13 of the indoor unit 20 confirms that the defrosting operation is currently performed, and turns on the defrost LED element on the display unit 12. At this time, the four sides and the outdoor fan 66 is kept on (step 133).

Operation of step 1 by step 133 is performed from the start of step 1 to reaching t2 (step 136).

When the condition of step 136 is satisfied, the value of the step counter for counting the defrosting operation step is increased by one, and the operation of the defrosting initial timer for counting the defrosting initial operation in each step is cleared (step 139).

That is, in the step (1) of the defrosting operation, by lowering the operating frequency of the compressor step by step, while avoiding side effects due to sudden changes in the operating frequency of the compressor, in all directions 66 when suddenly changed from the heating mode to the cooling mode It is intended to prevent side effects due to pressure differences that may occur.

By performing the step 139, the defrosting operation step becomes step ② (step 142).

Step ② of the defrosting operation is shown in step 2 in FIG.

In step ② of the defrosting operation, the defrosting operation frequency of the compressor 64 is controlled in the same manner as in step ①. At this time, the microprocessor 50 turns off the operation of the four sides and the fan 66, and clears the four sides on flag. Then, the outdoor fan off flag is set (step 145).

When the control in the step 145 is performed, the compressor 64 is continuously controlled at the defrosting operation frequency Fc-1 determined in step (1), and the operation of the four sides and the outdoor fan 66 is stopped. The system is switched to a cooling cycle as the operation of the four sides is turned off. At this time, since the operating frequency of the compressor 64 is controlled by the frequency lowered by one step from the cooling rated operating frequency, it is intended to adjust the pressure difference that may be generated according to the switching of the four sides to a minimum.

When the system is controlled by the cooling cycle as described above, the high temperature and high pressure refrigerant flows through the pipe connected to the heat exchanger 15 side of the outdoor unit 30 side. Therefore, the above-mentioned ice freezing of the heat exchanger 15 starts to thaw by the refrigerant of high temperature and high pressure.

On the other hand, the microprocessor 50 compares whether the outdoor piping temperature is greater than T3 ℃ after the control in the step 145 (step 148). The outdoor pipe temperature is made through the sensor 54 and the outdoor pipe temperature sensing unit 52.

When the outdoor piping temperature is detected to be higher than T3 ° C. and the time is maintained for t9 or more (step 151), the value of the step counter for counting the defrosting operation step is set to?. Then, the timer for counting the defrosting initial operation is cleared (step 154). That is, in step 154, it is determined that no further defrosting operation is necessary and the defrosting operation operation proceeds from step ② to step ④.

However, when the outdoor pipe temperature is lower than T3 ° C. or when the outdoor pipe temperature is higher than T3 ° C., the time for performing the defrosting operation ② step has elapsed (t3). step).

When the condition of step 160 is satisfied, the microprocessor 50 increments the step counter by one to count the defrosting operation step. The timer for counting the defrosting initial operation is also cleared (step 163).

By the step 163, the defrosting operation step becomes step ③ (step 166), and by the step 154, the defrosting operation step becomes step ④ (step 200).

The defrosting operation ③ step is shown by 3 in FIG. 4.

In the step (3) of the defrosting operation, the outdoor fan flag for indicating that the outdoor fan is in operation during the defrosting operation is cleared (step 169), and it is determined whether the defrosting operation according to step 3 has elapsed (t4) (step 172). ). Or, it is determined whether the outdoor pipe temperature is higher than T4 ° C. (step 178).

When the conditions of steps 172 and 178 are satisfied, the microprocessor 50 terminates the defrosting operation according to step ③ and increments the step counter for counting the defrosting operation step by one. The operation of the timer for counting the defrosting initial operation time is also cleared (step 175). That is, the microprocessor 50 terminates the defrosting operation by the step (3) to prevent the defrosting operation for a long time when the outdoor piping temperature is T4 ℃ or more, or when the defrosting operation time by the step (3) exceeds t4. .

However, when the conditions of steps 172 and 178 are not satisfied, the microprocessor 50 determines whether the outdoor pipe temperature detected by the outdoor pipe temperature detecting unit 52 is higher than T1 ° C. (step 181). ).

When the outdoor pipe temperature detected by the sensor 54 and converted into an electrical signal through the outdoor pipe temperature sensing unit 52 and input to the microprocessor 50 is greater than T1 ° C., and the time passes t8 ( Step 193), the microprocessor 50 terminates the defrosting operation by the defrosting operation ③ step and increments the step counter for counting the defrosting operation step by one. Then, in each defrosting operation step, the defrost second timer that counts the operation time in seconds is cleared (step 175).

That is, the microprocessor 50 terminates the defrosting operation by the step (3) when the outdoor piping temperature is T1 ° C or more and the time t8 has elapsed.

However, in step 181, when the outdoor pipe temperature is lower than T1 ° C. or the time when the outdoor pipe temperature is higher than T1 ° C. does not pass t8, it is determined whether the outdoor pipe temperature is higher than T5 ° C (step 187).

In step 187, when the detected outdoor piping temperature is greater than T5 ° C, when the holding time of T5 ° C or more has passed t10 (step 196), the defrosting operation frequency is one step from the maximum rated frequency during heating operation. The lowering, and determines the compressor defrosting operation frequency (step 199).

However, when the outdoor pipe temperature currently detected in step 187 is less than T5 ° C, the defrosting operation frequency is determined as the maximum rated frequency during the heating operation, and the operation of the compressor is controlled (step 190). At this time, the operation of the timer for counting the holding time over T5 ° C is also cleared.

Therefore, the defrosting operation frequency of the compressor in the ③ phase of defrosting operation is determined by lowering one step at the maximum heating frequency when the outdoor piping temperature is higher than T5 ℃ and lower than T1 ℃, and the maximum heating when the outdoor piping temperature is lower than T5 ℃. Determined by the rated frequency, the compressor 64 is operated. In other words, the compressor is operated at the maximum rated frequency of heating at the time of defrosting operation, thereby improving the efficiency of the defrosting operation.

Further, in the step (3) of the defrosting operation, step 3 is performed even when the operation by step 3 has passed t4, the outdoor piping temperature is higher than T4 ° C, or the outdoor piping temperature is higher than T1 ° C, and the time has elapsed t8. The defrosting operation step is terminated to prevent defrosting for a long time.

Next, step ④ of the defrosting operation is shown as ④ in FIG. 4.

The step ④ of the defrosting operation starts after step 154 in step ②, after step 175 and step 193 in step ③ (step 200).

Step ④ of the defrosting operation is to lower the operating frequency of the compressor again. That is, the defrosting operation frequency of the compressor is controlled by one step lowering from the cooling rated operation frequency (step 203).

The operation time of the compressor 64 by the defrosting operation frequency adjusted by the step 203 is performed for t5 after the step ③ of the defrosting operation is completed (step 206).

Thereafter, the value of the step counter for counting the defrosting operation stage is increased by 1, and in each defrosting operation stage, the defrost second timer for counting the operation time in seconds is cleared (step 209).

By performing step 209, the defrosting operation step is 5 (step 212).

Five steps of the defrosting operation are shown in ⑤ in FIG. 4.

In step 5, the compressor is turned off. Therefore, the defrost frequency of the compressor is controlled to 0 to stop the operation of the compressor. Then, the outdoor fan 66 is driven while the outdoor fan on flag is set (step 215).

The driving of the outdoor fan 66 starts the operation of the outdoor fan 66 while controlling the operation of the relay driver 68 in the microprocessor 50.

The off operation time of the compressor by the control of the step 215 is performed for t6 after the completion of the fourth step of the defrosting operation (step 218).

When the condition of step 218 is satisfied, the value of the step counter for counting the defrosting operation step is increased by one, and the operation of the defrost second timer that counts the defrosting operation in seconds in each step is cleared ( Step 221).

By performing the step 221, the defrosting operation step is step ⑥ (step 224).

Step ⑥ of the defrosting operation is a step of starting the heating operation again while completing the defrosting.

That is, the operation frequency of the compressor is adjusted from the heating rated frequency to one step higher frequency, and the operation of the four sides is turned on while setting the four sides flag. Therefore, the system is returned to the heating cycle again (step 227).

The operation of controlling the compressor according to the step 227 from the heating rated frequency to the first high frequency is performed for t7 after the defrosting operation according to the fifth step is completed (step 230).

Accordingly, in the sixth step of the defrosting operation, the step counter for counting the defrosting operation operation step is cleared, the defrosting operation timer is cleared, and a flag indicating that the defrosting operation is being performed is cleared (step 233). The microprocessor 50 transmits the completion of the defrosting operation to the indoor unit 20 when all the defrosting operations are completed. Therefore, the LED device indicating that the defrosting operation is performed on the display unit 53 is turned off.

Thereafter, the compressor is controlled at the heating operation set frequency, and normal heating operation is performed while all operations of the four sides, the outdoor fan, and the indoor fan are resumed.

As described above, the defrosting operation control of the present invention controls the defrosting operation while controlling the defrosting operation execution conditions in accordance with the defrosting operation time and the outdoor piping temperature from the start of the defrosting to the end of the defrosting.

Therefore, the present invention obtains the following effects.

First, since the start point of the defrosting is determined by the reheating operation time and the outdoor piping temperature, there is an effect of preventing the defrosting condition from being continuously made in a state where the outdoor temperature is very low.

Secondly, after gradually lowering the operating frequency of the compressor, by switching from the heating cycle to the cooling cycle there is an effect to minimize the pressure difference generated during the mode switching.

Third, when entering the defrosting operation in earnest, there is an effect that the defrosting is performed in a short time by controlling the operating frequency of the compressor at the heating maximum operating frequency.

Fourth, the defrosting operation is terminated when the outdoor temperature is maintained at 25 ° C or higher for 250 seconds or when the time controlled by the heating maximum operating frequency exceeds 8 minutes, thereby preventing the defrosting operation for a long time. .

Fifth, by controlling the operation of the four sides, outdoor fan, indoor fan step by step, when performing the defrosting operation, it is possible to prevent the system performance mistake by preventing the discharge of cold wind to the indoor side. .

Sixth, when the mode is switched from heating operation to defrosting operation and heating operation again, the operation frequency of the compressor is lowered step by step, or stepped up, thereby preventing the performance degradation of the compressor by the sudden operation frequency control. There is.

Finally, there is an advantage that a more complete defrosting can be performed by controlling the operation step during the defrosting operation step by step according to the state of the current system, and by varying the defrosting condition according to the state of the current system.

Claims (5)

Determining the start point of the defrosting operation based on the reheating operation time and the outdoor piping temperature; When the defrosting operation is started, the operation frequency of the compressor is lowered to change the cycle, and then the operating frequency of the compressor is increased again to perform the defrosting operation; Determining the end point of the defrosting operation based on the defrosting time or the outdoor pipe temperature during the defrosting operation; And deactivating the operating frequency of the compressor by completely stopping the motor at the end of the defrosting operation and completely stopping the defrosting operation. The method of claim 1, The defrosting operation start time is the defrosting operation control method of the inverter air conditioner, characterized in that when the reheating operation time has passed a predetermined time, the outdoor piping temperature is below a predetermined temperature. The method of claim 1, The defrosting operation end point is a defrosting operation control method of the inverter air conditioner, characterized in that when the defrosting operation time has passed a predetermined time. The method of claim 1, The defrosting operation end point is a defrosting operation control method of the inverter air conditioner, characterized in that is made when the outdoor piping temperature rises above a predetermined temperature. The method according to any one of claims 1 to 4, And controlling the operation to be performed within a rated frequency range for a predetermined time after the start of the heating operation.