Frequency adjusting method for variable-frequency air source heat pump unit

Abstract

The invention discloses a frequency adjusting method for a variable-frequency air source heat pump unit, and belongs to the technical field of air source heat pump control. The method specifically comprises the following steps of: 1, dividing a control temperature region; 2, performing frequency regulation calculation; the temperature area comprises a sudden stop area, an unloading area, a maintaining area and a loading area, the sudden stop area is a temperature interval when the heat pump unit stops running, the unloading area is a temperature interval when the heat pump unit needs forced frequency reduction, the maintaining area is a temperature interval when the heat pump unit needs working frequency maintaining, and the loading area is a temperature interval when the heat pump unit needs frequency increasing; after the heat pump unit reaches the set temperature, all the variable-frequency compressors in the heat pump unit firstly reduce the set load rate rotating speed and operate for 10 min at the reduced frequency, according to the frequency adjusting method of the variable-frequency air source heat pump unit, single-direction frequency adjustment and compensation for the electronic expansion valve are adopted, the refrigerant flow of a refrigerating system is greatly stabilized, and the refrigerating efficiency is improved. And the refrigerating system is in an efficient and stable state.

Description

Technical Field

[0001] The present invention specifically relates to a frequency regulation method for a variable frequency air source heat pump unit, and belongs to the technical field of air source heat pump control. Background Art

[0002] At present, the frequency regulation method adopted by variable frequency air source heat pump water heaters is to use the difference between the target temperature of the water tank and the instantaneous temperature of the water tank as the feedback object, that is, when the temperature difference between the two is greater than a certain value, the compressor is operated at a high frequency as much as possible to increase the heat production (heating operation) and shorten the heating time. When the temperature difference between the two is less than a certain value, the compressor frequency is dynamically adjusted to stabilize the water tank temperature within the target temperature range (stable operation); for example, the Chinese patent authorization announcement number: CN104613651B discloses a frequency regulation method for variable frequency air source heat pump water heaters, which can make the variable frequency The heat pump water heater works at a frequency as close to the optimal energy efficiency ratio frequency point as possible to save energy; the variable frequency air source heat pump units currently on the market will perform load addition and reduction actions after reaching the set temperature. During the load addition and reduction actions, the compressor will frequently increase and decrease the frequency. Because the response of the refrigeration system itself is very slow, the steady-state time is about 10 minutes. Therefore, frequent frequency increases and decreases lead to refrigerant flow disturbances, and refrigerant flow disturbances lead to reduced refrigeration capacity. In severe cases, it can cause false defrosting under low-temperature heating conditions, resulting in changes in the delivery water temperature, resulting in a poor room temperature experience for customers. Summary of the invention

[0003] To solve the above problems, the present invention proposes a frequency regulation method for a variable frequency air source heat pump unit, which adopts single-direction frequency modulation and compensation for the electronic expansion valve, greatly stabilizes the refrigerant flow of the refrigeration system, and puts the refrigeration system in an efficient and stable state.

[0004] The frequency adjustment method of the variable frequency air source heat pump unit of the present invention is as follows: The first step is to divide the control temperature into areas, which include an emergency stop area, an unloading area, a holding area and a loading area. The emergency stop area is the temperature interval where the heat pump unit stops running, the unloading area is the temperature interval where the heat pump unit needs to be forced to reduce the frequency, the holding area is the temperature interval where the heat pump unit needs to maintain the operating frequency, and the loading area is the temperature interval where the heat pump unit needs to increase the frequency; The second step is frequency adjustment calculation; the calculation process is as follows: 2.1. After the heat pump unit reaches the set temperature, all variable frequency compressors in the heat pump unit first reduce the set load rate speed. The load rate speed refers to: when different systems and different loads meet the frequency modulation requirements of the set water temperature, for example: when the system has a small load or the heating environment temperature is high / the cooling environment temperature is low, the load rate speed value is relatively large, and when the system has a large load or the heating environment temperature is low / the cooling environment temperature is high, the load rate speed value is relatively small; keep the reduced frequency running for 10 minutes, and then judge the load rate speed again. If the current load rate speed is greater than the set minimum load rate speed, perform periodic forced frequency reduction processing. The processing process is as follows: 2.2. Cycle forced frequency reduction: If the control temperature is in the unloading zone or emergency stop zone, all variable frequency compressors of the heat pump unit will be forced to reduce the frequency every set forced frequency reduction cycle. The frequency of forced frequency reduction is processed according to the control temperature change trend within the cycle; 2.2.1. The current load rate speed in step 2.1 is less than or equal to the set minimum load rate speed; or during the periodic forced frequency reduction process, after the frequency of the variable frequency compressor is reduced to the set minimum load rate speed, the frequency is not further reduced, and it continues to run at the minimum load rate speed for 10 minutes, and then the following judgment is made again to determine whether the control temperature is in a certain area, as follows: a1. If the controlled temperature is still in the emergency stop zone, stop the corresponding variable frequency compressor; b1. If the temperature control temperature is in the holding zone or unloading zone, continue to run at the lowest load rate and speed. During operation, if the temperature control changes into the loading zone, jump to step c1; if the temperature control changes to the unloading zone, return to step 2.2.1; c1. If the temperature is in the loading zone and lasts for more than 10 minutes, the frequency will be increased again; if the temperature changes to the holding zone, the timer will be reset and the process will return to step b1; if the temperature changes to the unloading zone or emergency stop zone, the timer will be reset and the process will return to step 2.2.1; 2.2.2. The compressor frequency has not dropped to the set minimum load rate speed, and the control temperature is determined to be in a certain area, as follows: a2. Control the temperature to the loading zone: if it is in the loading zone for more than 10 minutes, re-upgrade the frequency; if it changes to the holding zone in the middle, the timer is reset and jump to b2; if it changes to the unloading zone or emergency stop zone in the middle, the timer is reset and jump to step c2; b2. If the control temperature is still in the holding zone, the current frequency is maintained. If it changes to the loading zone midway, jump to step a2; if it changes to the unloading zone or the emergency stop zone midway, jump to step c2; c2. When the controlled temperature returns to the unloading area or the emergency stop area, return to step 2.2 and continue the cycle forced frequency reduction.

[0005] Furthermore, the frequency of the forced frequency reduction is processed according to the control temperature change trend within the cycle as follows: When the collected control temperature is in a downward trend, it is determined that the current state is cooling or heating. When in the heating state, all the variable frequency compressors in the heat pump unit will reduce the first forced frequency reduction frequency again at the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit will reduce the third forced frequency reduction frequency again at the current working frequency; When the collected control temperature is in a temperature holding state, the temperature holding state means that the temperature fluctuation value is within ±0.5°C. At this time, all variable frequency compressors in the heat pump unit reduce the second forced frequency reduction frequency again at the current operating frequency; When the collected control temperature is on an upward trend, it is determined that the current state is cooling or heating. When in the heating state, all variable frequency compressors in the heat pump unit reduce the third forced frequency reduction frequency again at the current working frequency; when in the cooling state, all variable frequency compressors in the heat pump unit reduce the first forced frequency reduction frequency again at the current working frequency; the temperature is controlled by selecting the first forced frequency reduction frequency and the third forced frequency reduction frequency, so that the temperature re-enters the temperature holding state; the frequency calculation process of the frequency increase is the inverse process of the frequency calculation process of the forced frequency reduction, which is as follows: When the collected control temperature is in a downward trend, it is determined that the current state is cooling or heating. When in the heating state, all the variable frequency compressors in the heat pump unit increase the third forced frequency reduction frequency again on the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit increase the first forced frequency reduction frequency again on the current working frequency; When the collected control temperature is in a temperature holding state, the temperature holding state means that the temperature fluctuation value is within ±0.5°C. At this time, all variable frequency compressors in the heat pump unit increase the second forced frequency reduction frequency again at the current operating frequency; When the collected control temperature is on an upward trend, it is determined that the current state is in cooling state or heating state. When in heating state, all variable frequency compressors in the heat pump unit increase the first forced frequency reduction frequency again on the current working frequency; when in cooling state, all variable frequency compressors in the heat pump unit increase the third forced frequency reduction frequency again on the current working frequency; the temperature is controlled by selecting the first forced frequency reduction frequency and the third forced frequency reduction frequency, so that the temperature re-enters the temperature keeping state.

[0006] Furthermore, the minimum load rate rotation speed is a cooling minimum load rate rotation speed or a heating minimum load rate rotation speed.

[0007] Furthermore, when the load rate and speed are adjusted, the number of steps of the throttling element electronic expansion valve is adjusted synchronously, and the adjustment process is as follows: The number of adjustment steps of the throttling element electronic expansion valve = the current number of steps of the throttling element electronic expansion valve - the number of reduction steps, and the reduction step number is calculated as follows: (the current number of steps of the throttling element electronic expansion valve * the frequency reduction / frequency increase coefficient * the basic frequency reduction / frequency increase step number * the load rate speed) / 100 = 103 steps, and the number of adjustment steps of the throttling element electronic expansion valve is calculated after rounding the above reduction steps; and the number of adjustment steps of the throttling element electronic expansion valve is executed; the load rate speed is the set load rate speed in step 2.1.

[0008] Furthermore, the frequency reduction / up-conversion coefficient is set to 0.2, and the basic frequency reduction / up-conversion step number is set to 4.

[0009] Compared with the prior art, the frequency regulation method of the variable frequency air source heat pump unit of the present invention solves the instability of the refrigeration system caused by frequent frequency modulation of the variable frequency air source heat pump. The frequency modulation in one direction and the compensation for the electronic expansion valve greatly stabilize the refrigerant flow of the refrigeration system, so that the refrigeration system is in an efficient and stable state; the control temperature is always maintained in a suitable temperature range, the start and stop of the compressor is reduced and the control temperature change is reduced, thereby obtaining a low-noise, high-energy-efficiency and highly stable variable frequency air source heat pump system; by dividing the control temperature into areas, the control optimization of user systems with large and small loads is carried out, the refrigerant flow is processed in a steady state, the control temperature is optimized more stably, and the indoor temperature changes are smaller; in actual applications, through this method, the compressor frequency runs at a low frequency most of the time, which not only saves more energy and electricity by more than 20% compared with the fixed frequency air source heat pump unit, but also has lower noise control and less CO2 emission control. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of temperature division areas in the cooling mode of the present invention.

[0011] Figure 2 It is a schematic diagram of temperature division areas in the heating mode of the present invention.

[0012] Figure 3 It is a schematic diagram of the frequency regulation method of the variable frequency air source heat pump unit of the present invention.

[0013] Figure 4 It is a schematic diagram of a compressor operating speed curve monitored in one day according to the present invention.

[0014] Figure 5 It is a schematic diagram of the temperature change curve of one-day monitoring and control of the present invention.

[0015] Reference numeral: T HSRT , heating set temperature, T CSRT , Refrigeration set temperature, T add , loading deviation value, T sub , unloading deviation value; DETAILED DESCRIPTION

[0016] like Figures 1 to 5 The frequency adjustment method of the variable frequency air source heat pump unit shown in the figure is as follows: The first step is to divide the control temperature into areas, which include an emergency stop area, an unloading area, a holding area, and a loading area. The emergency stop area is the temperature interval where the heat pump unit stops running, the unloading area is the temperature interval where the heat pump unit needs to be forced to reduce the frequency, the holding area is the temperature interval where the heat pump unit needs to maintain the operating frequency, and the loading area is the temperature interval where the heat pump unit needs to increase the frequency; specifically, Figure 1 and Figure 2 As shown, it is a schematic diagram of the division of temperature intervals, wherein the heating set temperature and the cooling set temperature are variable values, which can be set according to the external temperature requirements; the loading deviation value and the unloading deviation value are preset fixed values; when the interval is determined to be at the endpoint value of two intervals, if the endpoint value falls into the currently operating interval, the load rate speed remains unchanged; when the endpoint value falls into other intervals, it defaults to falling into an interval close to the current interval.

[0017] The second step is frequency adjustment calculation; the calculation process is as follows: 2.1. After the heat pump unit reaches the set temperature, all variable frequency compressors in the heat pump unit first reduce the set load rate speed. The load rate speed refers to the frequency modulation requirement for reaching the set water temperature when different systems and different loads are used. For example, when the system has a small load or the heating environment temperature is high / the cooling environment temperature is low, the load rate speed value is relatively large, and when the system has a large load or the heating environment temperature is low / the cooling environment temperature is high, the load rate speed value is relatively small; keep the reduced frequency running for 10 minutes, and then judge the load rate speed again. If the current load rate speed is greater than the set minimum load rate speed, perform periodic forced frequency reduction processing. The processing process is as follows: 2.2. Cycle forced frequency reduction: If the control temperature is in the unloading zone or emergency stop zone, all variable frequency compressors of the heat pump unit will be forced to reduce the frequency every set forced frequency reduction cycle. The frequency of forced frequency reduction is processed according to the control temperature change trend within the cycle; 2.2.1. The current load rate speed in step 2.1 is less than or equal to the set minimum load rate speed; or during the periodic forced frequency reduction process, after the frequency of the variable frequency compressor is reduced to the set minimum load rate speed, the frequency is not further reduced, and it continues to run at the minimum load rate speed for 10 minutes, and then the following judgment is made again to determine whether the control temperature is in a certain area, as follows: a1. If the controlled temperature is still in the emergency stop zone, stop the corresponding variable frequency compressor; b1. If the temperature control temperature is in the holding zone or unloading zone, continue to run at the lowest load rate and speed. During operation, if the temperature control changes into the loading zone, jump to step c1; if the temperature control changes to the unloading zone, return to step 2.2.1; c1. If the temperature is in the loading zone and lasts for more than 10 minutes, the frequency will be increased again; if the temperature changes to the holding zone, the timer will be reset and the process will return to step b1; if the temperature changes to the unloading zone or emergency stop zone, the timer will be reset and the process will return to step 2.2.1; 2.2.2. The compressor frequency has not dropped to the set minimum load rate speed, and the control temperature is determined to be in a certain area, as follows: a2. Control the temperature to the loading zone: if it is in the loading zone for more than 10 minutes, re-upgrade the frequency; if it changes to the holding zone in the middle, the timer is reset and jump to b2; if it changes to the unloading zone or emergency stop zone in the middle, the timer is reset and jump to step c2; b2. If the control temperature is still in the holding zone, the current frequency is maintained. If it changes to the loading zone midway, jump to step a2; if it changes to the unloading zone or the emergency stop zone midway, jump to step c2; c2. When the controlled temperature returns to the unloading area or the emergency stop area, return to step 2.2 and continue the cycle forced frequency reduction.

[0018] The frequency of the forced frequency reduction is processed according to the control temperature change trend within the cycle as follows: When the collected control temperature is in a downward trend, it is determined that the current state is cooling or heating. When in the heating state, all the variable frequency compressors in the heat pump unit will reduce the first forced frequency reduction frequency again at the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit will reduce the third forced frequency reduction frequency again at the current working frequency; When the collected control temperature is in a temperature holding state, the temperature holding state means that the temperature fluctuation value is within ±0.5°C. At this time, all variable frequency compressors in the heat pump unit reduce the second forced frequency reduction frequency again at the current operating frequency; When the collected control temperature is on an upward trend, it is determined that the current state is cooling or heating. When in the heating state, all variable frequency compressors in the heat pump unit reduce the third forced frequency reduction frequency again at the current working frequency; when in the cooling state, all variable frequency compressors in the heat pump unit reduce the first forced frequency reduction frequency again at the current working frequency; the temperature is controlled by selecting the first forced frequency reduction frequency and the third forced frequency reduction frequency, so that the temperature re-enters the temperature holding state; the frequency calculation process of the frequency increase is the inverse process of the frequency calculation process of the forced frequency reduction, which is as follows: When the collected control temperature is in a downward trend, it is determined that the current state is cooling or heating. When in the heating state, all the variable frequency compressors in the heat pump unit increase the third forced frequency reduction frequency again on the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit increase the first forced frequency reduction frequency again on the current working frequency; When the collected control temperature is in a temperature holding state, the temperature holding state means that the temperature fluctuation value is within ±0.5°C. At this time, all variable frequency compressors in the heat pump unit increase the second forced frequency reduction frequency again at the current operating frequency; When the collected control temperature is on an upward trend, it is determined that the current state is in cooling state or heating state. When in heating state, all variable frequency compressors in the heat pump unit increase the first forced frequency reduction frequency again on the current working frequency; when in cooling state, all variable frequency compressors in the heat pump unit increase the third forced frequency reduction frequency again on the current working frequency; the temperature is controlled by selecting the first forced frequency reduction frequency and the third forced frequency reduction frequency, so that the temperature re-enters the temperature keeping state.

[0019] The minimum load rate rotation speed is a cooling minimum load rate rotation speed or a heating minimum load rate rotation speed.

[0020] When the load rate and speed are adjusted, the number of steps of the throttling element electronic expansion valve is adjusted synchronously, and the adjustment process is as follows: The number of adjustment steps of the throttling element electronic expansion valve = the current number of steps of the throttling element electronic expansion valve - the number of reduction steps, and the reduction step number is calculated as follows: (the current number of steps of the throttling element electronic expansion valve * the frequency reduction / frequency increase coefficient * the basic frequency reduction / frequency increase step number * the load rate speed) / 100 = 103 steps, and the number of adjustment steps of the throttling element electronic expansion valve is calculated after rounding the above reduction steps; and the number of adjustment steps of the throttling element electronic expansion valve is executed; the load rate speed is the set load rate speed in step 2.1.

[0021] The down-frequency / up-frequency coefficient is set to 0.2, and the basic down-frequency / up-frequency step number is set to 4.

[0022] Example: The frequency regulation method of the variable frequency air source heat pump unit of the present invention is applied as follows: Small load heat pump unit operation heating (water temperature change rate δ is greater than 8℃ / 10min): (1) The set temperature is 50°C. When the control temperature reaches 50°C, all variable frequency compressors in the heat pump unit first reduce the set load rate speed. The set load rate speed is set to 40Hz, and the current speed is 95Hz. At this time, the current speed begins to be reduced to 55Hz; (2) The current number of steps of the throttling element electronic expansion valve is 322. In order to meet the change of refrigerant flow, the throttling element electronic expansion valve is adjusted synchronously, specifically: First, calculate the number of reduction steps of the throttling element electronic expansion valve: reduction step number = current throttling element electronic expansion valve 322 (current step number) * 0.2 (frequency reduction / frequency increase coefficient) * 4 (basic frequency reduction / frequency increase step number) * 40 (load rate speed) / 100 = 103 steps; then calculate and update the adjustment step number of the throttling element electronic expansion valve, adjustment step number = 322-103 = 219 steps; (3) At this time, the control temperature begins to slowly decrease. After 10 minutes, it is in the holding area. The compressor frequency of the unit maintains the current operating frequency; the control temperature is maintained between 47-50°C; (4) When the control temperature drops below 46°C due to external adjustment or load change, the frequency will be slowly increased to 65Hz according to the normal frequency increase cycle. At the same time, the control temperature will be detected. If it is between 47-50°C, it will continue to be maintained; (5) The throttling element electronic expansion valve calculates the increase step number according to step 2) based on the current value, and updates the adjustment step number; the adjustment step number is the current step number + the increase step number; (6) Continuously detect the control temperature zone, and continuously correct the compressor frequency and the number of steps of the electronic expansion valve.

[0023] like Figure 4 and Figure 5 As shown, the variable frequency air source heat pump unit adopts the variable frequency air source heat pump unit frequency adjustment method of the present invention, and runs the monitoring data (cooling) for one day, and obtains the following Figure 4 and Figure 5 The compressor speed monitoring curve and control temperature change curve shown in the figure are Figure 4 and Figure 5 It can be concluded that the monitored speed and temperature control are more stable and energy-efficient.

[0024] The above embodiments are only preferred implementations of the present invention, so any equivalent changes or modifications made according to the structures, features and principles described in the scope of application of the present invention are included in the scope of application of the present invention.

Claims

1. A frequency adjustment method for a variable frequency air source heat pump unit, characterized in that: The method is specifically as follows: The first step is to divide the control temperature into areas, which include an emergency stop area, an unloading area, a holding area and a loading area. The emergency stop area is the temperature interval where the heat pump unit stops running, the unloading area is the temperature interval where the heat pump unit needs to be forced to reduce the frequency, the holding area is the temperature interval where the heat pump unit needs to maintain the operating frequency, and the loading area is the temperature interval where the heat pump unit needs to increase the frequency; The second step is frequency adjustment calculation; the calculation process is as follows: 2.

1. After the heat pump unit reaches the set temperature, all variable frequency compressors in the heat pump unit first reduce the set load rate speed, maintain the reduced frequency for 10 minutes, and then perform load rate speed determination again. If the current load rate speed is greater than the set minimum load rate speed, a periodic forced frequency reduction process is performed. The processing process is as follows: 2.

2. Cycle forced frequency reduction: If the control temperature is in the unloading zone or emergency stop zone, all variable frequency compressors of the heat pump unit will be forced to reduce the frequency every set forced frequency reduction cycle. The frequency of forced frequency reduction is processed according to the control temperature change trend within the cycle; 2.2.

1. The current load rate speed in step 2.1 is less than or equal to the set minimum load rate speed; or during the periodic forced frequency reduction process, after the frequency of the variable frequency compressor is reduced to the set minimum load rate speed, the frequency is not further reduced, and it continues to run at the minimum load rate speed for 10 minutes, and then the following judgment is made again to determine whether the control temperature is in a certain area, as follows: a1. If the controlled temperature is still in the emergency stop zone, stop the corresponding variable frequency compressor; b1. If the temperature control temperature is in the holding zone or unloading zone, continue to run at the lowest load rate and speed. During operation, if the temperature control changes into the loading zone, jump to step c1; if the temperature control changes to the unloading zone, return to step 2.2.1; c1. If the temperature is in the loading zone and lasts for more than 10 minutes, the frequency will be increased again; if the temperature changes to the holding zone, the timer will be reset and the process will return to step b1; if the temperature changes to the unloading zone or emergency stop zone, the timer will be reset and the process will return to step 2.2.1; 2.2.

2. The compressor frequency has not dropped to the set minimum load rate speed, and the control temperature is determined to be in a certain area, as follows: a2. Control the temperature to the loading zone: if it is in the loading zone for more than 10 minutes, re-upgrade the frequency; if it changes to the holding zone in the middle, the timer is reset and jump to b2; if it changes to the unloading zone or emergency stop zone in the middle, the timer is reset and jump to step c2; b2. If the control temperature is still in the holding zone, the current frequency is maintained. If it changes to the loading zone midway, jump to step a2; if it changes to the unloading zone or the emergency stop zone midway, jump to step c2; c2. When the controlled temperature returns to the unloading area or the emergency stop area, return to step 2.2 and continue the cycle forced frequency reduction.

2. The frequency adjustment method of the variable frequency air source heat pump unit according to claim 1, characterized in that: The frequency of the forced frequency reduction is processed according to the control temperature change trend within the cycle as follows: When the collected control temperature is in a downward trend, it is determined that the current state is cooling or heating. When in the heating state, all the variable frequency compressors in the heat pump unit will reduce the first forced frequency reduction frequency again at the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit will reduce the third forced frequency reduction frequency again at the current working frequency; When the collected control temperature is in a temperature holding state, the temperature holding state means that the temperature fluctuation value is within ±0.5°C. At this time, all variable frequency compressors in the heat pump unit reduce the second forced frequency reduction frequency again at the current operating frequency; When the collected control temperature is on an upward trend, it is determined that the current state is in a cooling state or a heating state. When in the heating state, all the variable frequency compressors in the heat pump unit reduce the third forced frequency reduction frequency again on the current working frequency; when in the cooling state, all the variable frequency compressors in the heat pump unit reduce the first forced frequency reduction frequency again on the current working frequency; the temperature is controlled by selecting the first forced frequency reduction frequency and the third forced frequency reduction frequency, so that the temperature re-enters the temperature holding state; the frequency calculation process of the frequency increase is the inverse process of the frequency calculation process of the forced frequency reduction.

3. The frequency adjustment method of the variable frequency air source heat pump unit according to claim 1, characterized in that: The minimum load rate rotation speed is a cooling minimum load rate rotation speed or a heating minimum load rate rotation speed.

4. The frequency adjustment method of the variable frequency air source heat pump unit according to claim 1, characterized in that: When the load rate and speed are adjusted, the number of steps of the throttling element electronic expansion valve is adjusted synchronously, and the adjustment process is as follows: The number of adjustment steps of the throttling element electronic expansion valve = the current number of steps of the throttling element electronic expansion valve - the number of reduction steps, and the reduction step number is calculated as follows: (the current number of steps of the throttling element electronic expansion valve * the frequency reduction / frequency increase coefficient * the basic frequency reduction / frequency increase step number * the load rate speed) / 100 = 103 steps, and the number of adjustment steps of the throttling element electronic expansion valve is calculated after rounding the above reduction steps; and the number of adjustment steps of the throttling element electronic expansion valve is executed; the load rate speed is the set load rate speed in step 2.

1.

5. The frequency adjustment method of the variable frequency air source heat pump unit according to claim 4, characterized in that: The down-frequency / up-frequency coefficient is set to 0.2, and the basic down-frequency / up-frequency step number is set to 4.

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