CN102997368A - Intelligent defrosting control method for parallel multiple on-line unit with multiple compressors - Google Patents

Abstract

The invention discloses an intelligent defrosting control method for a parallel multiple on-line unit with multiple compressors. The intelligent defrosting control method comprises the following steps: (1) when the multiple on-line unit operates in a heating mode, continuously operates for 30-60 minutes, lasts for 2-5 minutes and satisfies one of the following conditions, an outdoor electrical control system emits a defrosting command; (2) a first direct-current inverter compressor starts a defrosting process after receiving the defrosting command; (3) a second direct-current inverter compressor starts a defrosting process after receiving a starting command; and (4) the first direct-current inverter compressor and the second direct-current inverter compressor exit the defrosting process if one of the following conditions is satisfied in the defrosting process. The intelligent defrosting control method is used for coordinating and controlling the action sequences of the components in the intelligent defrosting process, so that the air conditioner can normally enter the defrosting process, process the defrosting process and exit the defrosting process.

Description

Multi-compressor parallel multi-connection intelligent defrosting control method

technical field

The invention relates to the field of air-conditioning control, in particular to an intelligent defrosting control method for multi-compressor parallel connection and multi-connection.

Background technique

For heat pump air conditioners, the intelligent defrosting technology in the heating mode operation process is very important. This is because when the air conditioner is in heating operation, the outdoor temperature is low and the air humidity is high, It is easy to frost. After the outdoor heat exchanger is frosted, the frost layer blocks the passage between the aluminum fins of the outdoor heat exchanger, reducing the ventilation rate, and the reduction of the ventilation rate affects the heat exchange effect of the outdoor heat exchanger, making the frost layer thicker. The thicker it is, the worse the heat transfer effect is, thus forming a vicious circle. Therefore, a defrosting process must be carried out at regular intervals to melt the frost layer on the surface of the fins and restore the heat exchange effect of the outdoor heat exchanger. At present, the existing control methods involve intelligent defrosting methods for air-conditioning devices, and these methods are mainly limited to studying the entry conditions of air-conditioning device defrosting, the action control of the compressor and the action control of the four-way valve during the defrosting process, and the introduction of the defrosting process conditions of.

For the existing DC frequency conversion multi-connection technology, the basic modules have 5 specifications of 8 HP, 10 HP, 12 HP, 14 HP and 16 HP. However, the capacity of a single scroll DC inverter compressor is only 4 HP, 8 HP and 10 hp, etc. Therefore, when designing a 12 hp basic module, it is necessary to use a 4 hp and an 8 hp DC inverter compressor in parallel. Similarly, a 14 hp basic module must use a 4 hp and a 10 hp DC Inverter compressors are connected in parallel, and the 16-hp basic module must be composed of two 8-hp DC inverter compressors in parallel. In the DC frequency conversion multi-connection system with parallel compressors, in addition to the DC frequency conversion compressor, there are other control components, such as electronic expansion valves, four-way valves, indoor fan motors, outdoor fan motors, and various solenoid valves. It can be seen that the multi-compressor parallel multi-connection device is very complicated. In the process of intelligent defrosting, the sequence of actions of each control component in the control process, that is, the control sequence is very important, which can ensure the normal and reliable operation of the air conditioner. Entering the defrosting process, carrying out the defrosting process and releasing the defrosting process, and the prior art does not involve the method in this regard.

Contents of the invention

The technical problem to be solved by the present invention is to provide a system that can coordinate the action sequence between the various control parts in the intelligent defrosting process, so that the air conditioner can enter the defrosting process normally and reliably, perform the defrosting process, and exit the defrosting process. A multi-compressor parallel multi-connection intelligent defrosting control method for frost.

The technical solution of the present invention is to provide the following multi-compressor parallel multi-connection intelligent defrosting control method, including the following steps:

(1) When the multi-connected unit is running in heating mode, when it runs continuously for 30 to 60 minutes and meets one of the following conditions for 2 to 5 minutes, the outdoor electric control system will issue a defrosting command: ① If the outdoor environment detected by the outdoor temperature sensor When the temperature is ≤0°C and the defrosting temperature detected by the defrosting temperature sensor is ≤0.8×outdoor ambient temperature -10°C; ②If the outdoor ambient temperature detected by the outdoor temperature sensor is >0°C and the defrosting temperature sensor detects When the defrosting temperature is ≤0.2×outdoor ambient temperature -10°C;

(2) After the first DC inverter compressor receives the defrosting command, the operating frequency drops to 20-40Hz and runs for 10-20 seconds, then the operating frequency rises to 80-100Hz to start the defrosting process;

(3) After the second DC inverter compressor receives the start command, the operating frequency drops to 20-40Hz and runs for 10-20 seconds, then the operating frequency rises to 80-100Hz to start the defrosting process;

(4) During the defrosting process of the first DC inverter compressor and the second DC inverter compressor, if one of the following conditions is met, the defrosting process will be exited: ①The defrosting time exceeds 10 minutes; ②The defrosting temperature sensor detects The defrosting temperature is ≥12°C; ③The high-pressure pressure sensor detects the system high pressure ≥35Bar, at this time, the first DC inverter compressor and the second DC inverter compressor execute the exit defrosting control process, and the operating frequency drops to 20-40Hz After running for 10-20 seconds, increase to 50-60Hz and run for 10-20 seconds. After that, the operating frequency of the first DC variable frequency compressor and the second DC variable frequency compressor are transferred to the operating frequency before defrosting, and continue to automatically adjust and control;

(5) After receiving the defrosting command, both the first oil return solenoid valve and the second oil return solenoid valve are in the closed state;

(6) After the outdoor fan motor receives the defrosting instruction, it will stop after a delay of 10-15 seconds; until it exits defrosting, and the operating frequency of the first DC inverter compressor and the second DC inverter compressor drops to 20-40Hz After running for 10 to 20 seconds, the outdoor fan motor will be turned on to continue the automatic control process;

(7) After the four-way valve receives the defrosting instruction, it will be shut down after a delay of 10-15 seconds, and the operating frequency will drop to 20-20 after the first DC inverter compressor and the second DC inverter compressor exit defrosting. 5 to 10 seconds before the end of 40Hz operation, power on and start;

(8) After receiving the defrosting command, the opening of the heating electronic expansion valve increases to 350-480pls after a delay of 10-15 seconds. When the four-way valve is powered on and opened after the defrosting process, the heating electronic expansion valve opens. The opening of the valve starts to close until the system low pressure detected by the low pressure sensor is maintained at a level ≥ 0.5 Bar. The first DC variable frequency compressor and the second DC variable frequency compressor execute the exit defrosting control process, and the operating frequency is at the After a running frequency of 50-60Hz runs for 10-20 seconds, the opening of the heating electronic expansion valve rises to the opening before defrosting and runs for 50-70 seconds, after which it turns into an automatic control state;

(9) During the defrosting process, the air bypass solenoid valve and the liquid injection solenoid valve are both in the power-off and closed state;

(10) After receiving the defrosting command, the indoor unit that receives the start-up command will be delayed for 10 to 15 seconds, and the opening of the indoor electronic expansion valve will drop to 150pls. After that, the opening of the indoor electronic expansion valve will be 10pls./30s The rate of ~20pls./30s rises to 200~250pls. After the defrosting is completed, the four-way valve is powered on and opened, and it runs for 10min~15min at the opening before defrosting, and then enters the automatic adjustment control;

(11) After receiving the defrosting command, the indoor unit that has not received the start-up command will increase the opening of the indoor electronic expansion valve from 40-60pls. to 150pls. after a delay of 10-15 seconds, and then the indoor electronic expansion valve will open The temperature rises to 200-250pls. at a rate of 10pls./30s-20pls./30s. Exit the defrosting control process at the first DC inverter compressor and the second DC inverter compressor, and the operating frequency is at the second operating frequency After running at 50-60Hz for 10-20 seconds, the opening of the indoor electronic expansion valve drops to 40-60pls before defrosting;

(12) After receiving the defrosting command, the fan motor of the indoor unit that received the power-on command will stop after a delay of 10 to 15 seconds, and will be under anti-cold wind control after defrosting, that is, it is still in the shutdown state, preventing the indoor heat exchanger from When the temperature in the middle of the coil is lower than 25°C, cool air is blown until the temperature in the middle of the coil of the indoor heat exchanger is higher than 25°C, then the fan motor of the indoor unit is turned on, and the speed is adjusted according to the temperature in the middle of the coil;

(13) After receiving the defrosting command and during the entire defrosting process, the fan motor of the indoor unit that has not received the starting command is in a shutdown state.

After adopting the method of the above steps, the present invention has the following advantages compared with the prior art: the method of the present invention is to coordinate the action sequence between the various control components in the intelligent defrosting process, and to facilitate the normal and reliable operation of the air conditioner. Enter the defrost process, carry out the defrost process and exit the defrost.

Description of drawings

Fig. 1 is a structural schematic diagram of a DC inverter air conditioner refrigeration system controlled by the multi-compressor parallel multi-connection intelligent defrosting control method of the present invention.

Fig. 2 is a timing diagram of the actions of various components in the multi-compressor parallel multi-connection intelligent defrosting control method of the present invention.

Among them, 1. The first DC inverter compressor, 2. The first oil-gas separator, 3. The first check valve, 4. The first oil return solenoid valve, 5. The second DC inverter compressor, 6. The second Oil-gas separator, 7. Second one-way valve, 8. Second oil return solenoid valve, 9. Third one-way valve, 10. Gas bypass solenoid valve, 11. Four-way valve, 12. Outdoor heat exchanger, 13. Outdoor fan motor, 14. Fourth one-way valve, 15. Heating electronic expansion valve, 16. High-pressure liquid receiver, 17. Liquid injection solenoid valve, 18. Liquid supply stop valve, 19. Indoor electronic expansion valve, 20. Indoor fan motor, 21. Indoor heat exchanger, 22. Return air stop valve, 23. Gas-liquid separator, 24. Low-pressure pressure sensor, 25. First DC inverter compressor volleyball temperature sensor, 26. Second DC frequency conversion compressor ball temperature sensor, 27, high pressure pressure sensor, 28, indoor heat exchanger inlet temperature sensor, 29, indoor heat exchanger coil middle temperature sensor, 30, indoor heat exchanger outlet temperature sensor, 31, outdoor heat exchanger Heater coil middle temperature sensor, 32, defrosting temperature sensor, 33, outdoor ambient temperature sensor, 34, total return air temperature sensor.

Detailed ways

In order to better illustrate the technical solution of the present invention, the specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , in order to better illustrate the idea of the present invention, an example of a DC frequency conversion multi-line unit in which two DC frequency conversion compressors are connected in parallel is used as an example.

As shown in Figure 2, it is a schematic diagram of a DC frequency conversion multi-line system composed of two DC frequency conversion compressors connected in parallel, including: the first DC frequency conversion compressor 1, the first oil-gas separator 2, and the first one-way valve 3. The first oil return solenoid valve 4, the second DC inverter compressor 5, the second oil-gas separator 6, the second check valve 7, the second oil return solenoid valve 8, the third check valve 9, air bypass Solenoid valve 10, four-way valve 11, outdoor heat exchanger 12, outdoor fan motor 13, fourth one-way valve 14, heating electronic expansion valve 15, high pressure liquid receiver 16, liquid injection solenoid valve 17, liquid supply cut-off valve 18. Indoor electronic expansion valve 19, indoor electronic expansion valve 20, indoor fan motor 21, return air stop valve 22, gas-liquid separator 23, low-pressure pressure sensor 24, first DC inverter compressor volleyball temperature sensor 25, second DC inverter compressor ball temperature sensor 26, high pressure pressure sensor 27, indoor heat exchanger inlet temperature sensor 28, indoor heat exchanger coil middle temperature sensor 29, indoor heat exchanger outlet temperature sensor 30, outdoor heat exchanger coil middle A temperature sensor 31 , a defrosting temperature sensor 32 , an outdoor environment temperature sensor 33 , and a total return air temperature sensor 34 .

The implementation of a multi-compressor parallel multi-connection intelligent defrosting control method of the present invention will be described in detail below in combination with the above-mentioned DC inverter air conditioner:

Example 1:

(1) When the multi-split machine is running in heating mode, when it runs continuously for 30 minutes and meets the following conditions for 3 minutes, the outdoor electric control system will issue a defrosting command: if the outdoor ambient temperature detected by the outdoor temperature sensor is ≤0°C, And when the defrosting temperature detected by the defrosting temperature sensor 32 is ≤0.8×outdoor ambient temperature -10°C;

(2) After the first DC inverter compressor 1 receives the defrosting command, the operating frequency drops to 30Hz and runs for 20 seconds, then the operating frequency rises to 80Hz to start the defrosting process;

(3) After the second DC variable frequency compressor 2 receives the start instruction, the operating frequency drops to 30Hz and runs for 20 seconds, then the operating frequency rises to 80Hz to start the defrosting process;

(4) During the defrosting process of the first DC inverter compressor 1 and the second DC inverter compressor 2, if one of the following conditions is met, the defrosting process will be exited: ① The defrosting time exceeds 10 minutes; ② The defrosting temperature sensor 32 The detected defrosting temperature is ≥12°C; ③The high-pressure pressure sensor 27 detects that the system high pressure is ≥35 Bar. After the frequency drops to 40Hz and runs for 20 seconds, then rises to 60Hz and runs for 20 seconds. After that, the operating frequencies of the first DC inverter compressor 1 and the second DC inverter compressor 2 are transferred to the operating frequency before defrosting, and continue to automatically adjust and control;

(5) After receiving the defrosting command, both the first oil return solenoid valve 4 and the second oil return solenoid valve 8 are in the closed state;

(6) After the outdoor fan motor 13 receives the defrosting command, it will stop after 15 seconds; until it exits the defrosting, and the operating frequency of the first DC variable frequency compressor 1 and the second DC variable frequency compressor 2 drops to 40Hz. After 10 to 20 seconds, the outdoor fan motor is turned on to continue the automatic control process;

(7) After the four-way valve 11 receives the command to enter the defrost, it will be shut down after a 15-second delay, and the operating frequency will drop to 40Hz after the first DC inverter compressor 1 and the second DC inverter compressor 2 exit defrosting Power on 10 seconds before the end of the operation;

(8) After receiving the defrosting command, the opening of the heating electronic expansion valve 15 is delayed for 15 seconds and then rises to 350pls. The opening starts to close down until the low pressure of the system detected by the low pressure sensor 24 is maintained at a level ≥ 0.5 Bar. After the first DC inverter compressor 1 and the second DC inverter compressor 2 execute the exit defrosting control process, the operating frequency After running for 20 seconds at the second operating frequency of 560Hz, the opening of the heating electronic expansion valve 15 rises to the opening before defrosting and runs for 70 seconds, after which it turns into an automatic control state;

(9) During the defrosting process, the gas bypass solenoid valve 10 and the liquid injection solenoid valve 17 are both in the power-off and closed state;

(10) After receiving the defrosting command, the indoor unit that receives the start-up command will be delayed for 15 seconds, and the opening of the indoor electronic expansion valve 19 will drop to 150pls. After that, the indoor electronic expansion valve 19 will open at a rate of 10pls. Raise to 250pls. After the defrosting is over, the four-way valve 11 is powered on and opened for reversing, and runs at the opening degree before defrosting for 10 minutes, and then enters the automatic adjustment control;

(11) After receiving the defrosting command, the indoor electronic expansion valve 19 rises from 50pls. to 150pls. after a delay of 15 seconds for the indoor unit that has not received the start-up command, and then the indoor electronic expansion valve 19 opens at 10pls. The rate of /30s rises to 250pls. After the first DC inverter compressor 1 and the second DC inverter compressor 2 execute the exit defrosting control process, and the operating frequency runs at the second operating frequency of 60Hz for 20 seconds, the indoor electronic expansion The opening of valve 19 is reduced to 50pls. before defrosting;

(12) After receiving the defrosting command, the fan motor 20 of the indoor unit that received the start-up command will stop after a delay of 15 seconds. When the temperature in the middle of the tube is lower than 25°C, cool air is blown until the temperature in the middle of the indoor heat exchanger coil is higher than 25°C, then the fan motor of the indoor unit is turned on, and the speed is adjusted according to the temperature in the middle of the coil;

(13) After receiving the defrosting command and during the entire defrosting process, the fan motor of the indoor unit that has not received the starting command is in a shutdown state.

Example 2:

(1) When the multi-connected unit is running in heating mode, when the continuous operation is 30 minutes and the following conditions are met for 2 minutes, the outdoor electric control system will issue a defrosting command: if the outdoor ambient temperature detected by the outdoor temperature sensor 33 is >0°C , and when the defrosting temperature detected by the defrosting temperature sensor 32 is ≤0.2×outdoor ambient temperature -10°C;

(2) After the first DC inverter compressor 1 receives the defrosting command, the operating frequency drops to 30Hz and runs for 15 seconds, then the operating frequency rises to 90Hz to start the defrosting process;

(3) After the second DC variable frequency compressor 2 receives the start command, the operating frequency drops to 30Hz and runs for 15 seconds, then the operating frequency rises to 90Hz to start the defrosting process;

(4) During the defrosting process of the first DC inverter compressor 1 and the second DC inverter compressor 2, if one of the following conditions is met, the defrosting process will be exited: ① The defrosting time exceeds 10 minutes; ② The defrosting temperature sensor 32 The detected defrosting temperature is ≥12°C; ③The high-pressure pressure sensor 27 detects that the system high pressure is ≥35 Bar. After the frequency drops to 30Hz and runs for 10 seconds, then rises to 50Hz and runs for 10 seconds. After that, the operating frequencies of the first DC inverter compressor 1 and the second DC inverter compressor 2 are transferred to the operating frequency before defrosting, and continue to automatically adjust and control;

(5) After receiving the defrosting command, both the first oil return solenoid valve 4 and the second oil return solenoid valve 8 are in the closed state;

(6) After the outdoor fan motor receives the defrosting command, it will stop after 10 seconds; until it exits the defrosting, and the operating frequency of the first DC inverter compressor 1 and the second DC inverter compressor 2 drops to 30Hz for 10 seconds. After ~20 seconds, the outdoor fan motor is turned on to continue the automatic control process;

(7) After the four-way valve 11 receives the defrosting instruction, it will be shut down after a 10-second delay, and the operating frequency will drop to 30Hz after the first DC inverter compressor 1 and the second DC inverter compressor 2 exit defrosting Power on 5 seconds before the end of the operation;

(8) After receiving the defrosting command, the opening of the heating electronic expansion valve 15 is delayed for 10 seconds and then rises to 400pls. When the four-way valve is powered on and opened after the defrosting process, the heating electronic expansion valve 15 opens The temperature starts to be turned down until the system low pressure detected by the low pressure sensor 24 is maintained at a level ≥ 0.5 Bar, and the first DC inverter compressor 1 and the second DC inverter compressor 2 execute the exit defrosting control process, and the operating frequency is at After the second operating frequency is 60Hz for 10 seconds, the opening of the heating electronic expansion valve 15 rises to the opening before defrosting and runs for 50 seconds, after which it turns into an automatic control state;

(9) During the defrosting process, the gas bypass solenoid valve 10 and the liquid injection solenoid valve 17 are both in the power-off and closed state;

(10) After receiving the defrosting command, the indoor unit that receives the start-up command will be delayed for 10 seconds, and the opening of the indoor electronic expansion valve 19 will drop to 150pls. After that, the opening of the indoor electronic expansion valve 19 will be 20pls./30s After the defrosting is completed, the four-way valve 11 is powered on and turned on, and it runs for 10 minutes at the opening before defrosting, and then enters the automatic adjustment control;

(11) After receiving the defrosting instruction, the opening of the indoor electronic expansion valve 19 increases from 40pls. to 150pls. The rate of 20pls./30s rises to 200pls., after the first DC variable frequency compressor 1 and the second DC variable frequency compressor 2 execute the process of exiting the defrosting control, and the operating frequency runs at the second operating frequency of 60Hz for 10 seconds, the indoor The opening of electronic expansion valve 19 drops to 40pls before defrosting;

(12) After receiving the defrosting command, the indoor unit fan motor 20 that received the power-on command will stop after a delay of 10 seconds. When the temperature in the middle of the tube is lower than 25°C, cool air is blown until the temperature in the middle of the indoor heat exchanger coil is higher than 25°C, then the fan motor of the indoor unit is turned on, and the speed is adjusted according to the temperature in the middle of the coil;

(13) After receiving the defrosting command and during the entire defrosting process, the fan motor of the indoor unit that has not received the starting command is in a shutdown state.

Claims (1)

1. A multi-compressor parallel multi-connection intelligent defrosting control method, comprising the following steps: (1) When the multi-connected unit is running in heating mode, when it runs continuously for 30 to 60 minutes and meets one of the following conditions for 2 to 5 minutes, the outdoor electric control system will issue a defrosting command: ① If the outdoor environment detected by the outdoor temperature sensor When the temperature is ≤0°C and the defrosting temperature detected by the defrosting temperature sensor is ≤0.8×outdoor ambient temperature -10°C; ②If the outdoor ambient temperature detected by the outdoor temperature sensor is >0°C and the defrosting temperature sensor detects When the defrosting temperature is ≤0.2×outdoor ambient temperature -10°C; (2) After the first DC inverter compressor receives the defrosting command, the operating frequency drops to 20-40Hz and runs for 10-20 seconds, then the operating frequency rises to 80-100Hz to start the defrosting process; (3) After the second DC inverter compressor receives the start command, the operating frequency drops to 20-40Hz and runs for 10-20 seconds, then the operating frequency rises to 80-100Hz to start the defrosting process; (4) During the defrosting process of the first DC inverter compressor and the second DC inverter compressor, if one of the following conditions is met, the defrosting process will be exited: ①The defrosting time exceeds 10 minutes; ②The defrosting temperature sensor detects The defrosting temperature is ≥12°C; ③The high-pressure pressure sensor detects the system high pressure ≥35Bar, at this time, the first DC inverter compressor and the second DC inverter compressor execute the exit defrosting control process, and the operating frequency drops to 20-40Hz After running for 10-20 seconds, increase to 50-60Hz and run for 10-20 seconds. After that, the operating frequency of the first DC variable frequency compressor and the second DC variable frequency compressor are transferred to the operating frequency before defrosting, and continue to automatically adjust and control; (5) After receiving the defrosting command, both the first oil return solenoid valve and the second oil return solenoid valve are in the closed state; (6) After the outdoor fan motor receives the defrosting instruction, it will stop after a delay of 10-15 seconds; until it exits defrosting, and the operating frequency of the first DC inverter compressor and the second DC inverter compressor drops to 20-40Hz After running for 10 to 20 seconds, the outdoor fan motor will be turned on to continue the automatic control process; (7) After the four-way valve receives the defrosting instruction, it will be shut down after a delay of 10-15 seconds, and the operating frequency will drop to 20-20 after the first DC inverter compressor and the second DC inverter compressor exit defrosting. 5 to 10 seconds before the end of 40Hz operation, power on and start; (8) After receiving the defrosting command, the opening of the heating electronic expansion valve increases to 350-480pls after a delay of 10-15 seconds. When the four-way valve is powered on and opened after the defrosting process, the heating electronic expansion valve opens. The opening of the valve starts to close until the low pressure of the system detected by the low pressure sensor is maintained at a level ≥ 0.5 Bar. The first DC inverter compressor and the second DC inverter compressor execute the exit defrosting control process, and the operating frequency is at After the two operating frequencies of 50-60Hz run for 10-20 seconds, the opening of the heating electronic expansion valve rises to the opening before defrosting and runs for 50-70 seconds, after which it turns into the automatic control state; (9) During the defrosting process, the air bypass solenoid valve and the liquid injection solenoid valve are both in the power-off and closed state; (10) After receiving the defrosting command, the indoor unit that receives the start-up command will be delayed for 10 to 15 seconds, and the opening of the indoor electronic expansion valve will drop to 150pls. After that, the opening of the indoor electronic expansion valve will be 10pls./30s The rate of ~20pls./30s rises to 200~250pls. After the defrosting is completed, the four-way valve is powered on and opened, and it runs for 10min~15min at the opening before defrosting, and then enters the automatic adjustment control; (11) After receiving the defrosting command, the indoor unit that has not received the start-up command will increase the opening of the indoor electronic expansion valve from 40-60pls. to 150pls. after a delay of 10-15 seconds, and then the indoor electronic expansion valve will open The temperature rises to 200-250pls. at a rate of 10pls./30s-20pls./30s. Exit the defrosting control process at the first DC inverter compressor and the second DC inverter compressor, and the operating frequency is at the second operating frequency After running at 50-60Hz for 10-20 seconds, the opening of the indoor electronic expansion valve drops to 40-60pls before defrosting; (12) After receiving the defrosting command, the fan motor of the indoor unit that received the power-on command will stop after a delay of 10 to 15 seconds, and will be under anti-cold wind control after defrosting, that is, it is still in the shutdown state, preventing the indoor heat exchanger from When the temperature in the middle of the coil is lower than 25°C, cool air is blown until the temperature in the middle of the coil of the indoor heat exchanger is higher than 25°C, then the fan motor of the indoor unit is turned on, and the speed is adjusted according to the temperature in the middle of the coil; (13) After receiving the defrosting command and during the entire defrosting process, the fan motor of the indoor unit that has not received the starting command is in a shutdown state.

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