Variable frequency air conditioner room load calculation method, storage medium and air conditioner system

Abstract

The invention relates to an air conditioner control technology, discloses a variable-frequency air conditioner room load calculation method, a storage medium and an air conditioner system, and solves the problems that in the prior art, a variable-frequency air conditioner cannot be matched with a room load during capacity output due to the fact that the variable-frequency air conditioner cannot recognize the room load, and room temperature fluctuation is large; and the overshoot shutdown phenomenon cannot be avoided. The method comprises the following steps: calculating the output capacity of the air conditioner in real time during the operation of the air conditioner; and a preset time period serves as an iteration period, the room load range under the current indoor and outdoor temperature difference is iterated according to the output capacity, calculated in real time, of the air conditioner and the room temperature change direction, and when the room temperature change converges, the corresponding real-time output capacity of the air conditioner is the current room load. The invention is suitable for variable-frequency air conditioners.

Description

Technical Field

[0001] The present invention relates to air conditioning control technology, and in particular to a variable frequency air conditioning room load calculation method, a storage medium and an air conditioning system. Background Art

[0002] During operation, the frequency of the inverter air conditioner is generally controlled according to the difference between the set temperature and the ambient temperature. Taking the cooling mode as an example, when the ambient temperature is much higher than the set temperature, it means that the inverter air conditioner needs to run at a high frequency to output a large cooling capacity to keep the room temperature down; conversely, when the room temperature is close to the set temperature, it needs to run at a low frequency to reduce the output of the inverter air conditioner to prevent the room temperature from being too low or even below the set temperature and causing an overshoot and shutdown.

[0003] Although this control logic reflects the capacity adjustment advantage of variable frequency air conditioners, the specific load size of the room is unknown. Different usage scenarios, sunlight, heat leakage and room usage area will cause the actual room load to vary greatly. If the air conditioner cannot identify the room load, it will not be able to match the room load when outputting capacity, resulting in large fluctuations in room temperature. It is also unavoidable that over-adjustment shutdowns of cooling and heating will occur, resulting in increased energy consumption and an uncomfortable experience for consumers. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to propose a variable frequency air conditioner room load calculation method, storage medium and air conditioning system, so as to solve the problem that the variable frequency air conditioner in traditional technology cannot identify the room load and cannot match the room load when outputting power, resulting in large fluctuations in room temperature and unavoidable overshoot and shutdown.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] On the one hand, the present invention provides a method for calculating room load of a variable frequency air conditioner, which is applied to a variable frequency air conditioner, wherein the air inlet and the air outlet of the indoor unit heat exchanger of the variable frequency air conditioner are respectively provided with temperature and humidity sensors, and the method comprises the following steps:

[0007] During the operation of the air conditioner, the output capacity of the air conditioner is calculated in real time. With the preset time period as the iteration period, the room load range under the current indoor and outdoor temperature difference is iterated according to the real-time calculated output capacity of the air conditioner and the direction of room temperature change. When the room temperature change converges, the corresponding real-time output capacity of the air conditioner is the current room load.

[0008] Furthermore, the method for calculating the output capacity of the air conditioner in real time includes:

[0009] According to the dry-bulb temperature and relative humidity collected by the temperature and humidity sensors installed at the air inlet and air outlet of the indoor unit heat exchanger, the air enthalpy value of the air at the air inlet and the air outlet are calculated respectively;

[0010] Calculating the real-time air enthalpy difference per unit mass under the current working mode of the air conditioner according to the air inlet air enthalpy value and the air outlet air enthalpy value;

[0011] The real-time output capacity of the air conditioner in the current working mode is calculated based on the real-time air enthalpy difference per unit mass and the air quality per unit time at the air outlet in the current working mode of the air conditioner.

[0012] Further, according to the dry-bulb temperature and relative humidity collected by the temperature and humidity sensors provided at the air inlet and the air outlet of the indoor unit heat exchanger, the method of respectively calculating the air enthalpy value at the air inlet and the air outlet includes:

[0013] Firstly, according to the collected dry bulb temperatures of the air inlet and outlet, the air saturated vapor pressure at the air inlet and outlet is calculated using the air saturated vapor pressure calculation formula;

[0014] Then, according to the saturated steam pressure of the air at the air inlet and the air outlet and the relative humidity at the air inlet and the air outlet, the moisture content at the air inlet and the air outlet is calculated using the moisture content formula;

[0015] Next, according to the moisture content at the air inlet and the air outlet, the enthalpy value of the air at the air inlet and the air outlet are calculated using the enthalpy value calculation formula.

[0016] Furthermore, according to the air inlet air enthalpy value and the air outlet air enthalpy value, a method for calculating the real-time unit mass air enthalpy difference in the current working mode of the air conditioner includes:

[0017] If the current working mode is cooling mode, then:

[0018] Δh.c=h.jf-h.cf

[0019] Among them, Δh.c is the real-time unit mass air enthalpy difference in cooling mode; h.jf is the air enthalpy value at the air inlet; h.cf is the air enthalpy value at the air outlet;

[0020] If the current working mode is heating mode, then:

[0021] Δh.h=h.cf-h.jf

[0022] Among them, Δh.h is the real-time unit mass air enthalpy difference in heating mode; h.cf is the air enthalpy value at the air outlet; h.jf is the air enthalpy value at the air inlet.

[0023] Furthermore, the method for calculating the air quality per unit time at the air outlet includes:

[0024] Determine the corresponding air density based on the dry-bulb temperature collected by the temperature and humidity sensor installed at the air outlet;

[0025] Determine the air volume corresponding to the current gear speed of the air conditioner in the current mode;

[0026] The air quality per unit time at the air outlet is calculated according to the determined corresponding air density and the corresponding air volume at the current gear speed of the air conditioner in the current mode.

[0027] Furthermore, the method of determining the air volume corresponding to the current gear speed of the air conditioner in the current mode includes:

[0028] The corresponding air volume at each speed of cooling and heating is calibrated in advance by the enthalpy difference laboratory;

[0029] When the air conditioner is running, the pre-calibrated corresponding air volume is called according to the current working mode and gear speed.

[0030] Furthermore, the method of iterating the room load range under the current indoor and outdoor temperature difference based on the output capacity of the air conditioner and the room temperature change direction calculated in real time with a preset time period as the iteration period includes:

[0031] If the air conditioner is currently working in cooling mode:

[0032] If the average room temperature in this cycle is lower than the average room temperature in the previous cycle, it means that the room load is less than the average output capacity of the air conditioner in this cycle;

[0033] If the average room temperature in this cycle is higher than the average room temperature in the previous cycle, it means that the room load is greater than the average output capacity of the air conditioner in this cycle;

[0034] If the air conditioner is currently working in heating mode:

[0035] If the average room temperature in this cycle is lower than the average room temperature in the previous cycle, it means that the room load is greater than the average output capacity of the air conditioner in this cycle;

[0036] If the average room temperature in this cycle is higher than the average room temperature in the previous cycle, it means that the room load is less than the average output capacity of the air conditioner in this cycle.

[0037] Furthermore, the room temperature change convergence means that the average room temperature in the current cycle remains unchanged compared with the average room temperature in the previous cycle.

[0038] In a second aspect, the present invention further provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned variable frequency air conditioner room load calculation method.

[0039] In a third aspect, the present invention further provides an air conditioning system, which includes a processor and a memory, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned variable frequency air conditioning room load calculation method by executing the computer program.

[0040] The beneficial effects of the present invention are:

[0041] The present invention calculates the output capacity of the air conditioner in real time and performs iterative calculations in combination with the changing trend of the indoor temperature, thereby obtaining the current dynamic load of the room so that the air conditioner can grasp the size and changing direction of the room load in real time, thereby controlling the variable frequency air conditioner capacity output to adapt to the room load. This not only allows the variable frequency air conditioner to maintain stable operation, avoid room temperature fluctuations, solve the overshoot problem, and improve user experience, but also can reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of real-time calculation of air conditioner output capacity in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention aims to provide a method for calculating the room load of a variable frequency air conditioner, a storage medium and an air conditioning system, so as to solve the problem that the variable frequency air conditioner in the traditional technology cannot identify the room load and cannot match the room load when outputting the capacity, resulting in large fluctuations in the room temperature and the unavoidable overshooting and shutdown phenomenon. The core idea is that when the capacity output of the air conditioner acts on the room, it will bring about temperature changes in the room, and the temperature change trend in the room is determined by the current room load and the current air conditioner output capacity. Therefore, by calculating the real-time output capacity of the air conditioner and combining the temperature change direction in the room, the current room load range can be determined. On this basis, through iteration, when the temperature change in the room converges, the corresponding real-time output capacity of the air conditioner is the current room load. In this way, the air conditioner can grasp the size and change direction of the room load in real time, so as to control the capacity output of the variable frequency air conditioner to adapt to the room load, which can not only keep the variable frequency air conditioner in stable operation, avoid room temperature fluctuations, but also solve the overshooting and shutdown problem.

[0044] The scheme of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0045] Example

[0046] The variable frequency air conditioner room load calculation method provided in this embodiment includes: calculating the output capacity of the air conditioner in real time during the operation of the air conditioner; taking a preset time period as an iteration period, iterating the room load range under the current indoor and outdoor temperature difference according to the real-time calculated output capacity of the air conditioner and the direction of room temperature change; when the room temperature change converges, the corresponding real-time output capacity of the air conditioner is the current room load.

[0047] Wherein, the air conditioner is provided with temperature and humidity sensors at the air inlet and the air outlet of the indoor unit heat exchanger, respectively, for detecting the dry-bulb temperature and relative humidity as part of the input parameters for subsequent calculations.

[0048] The following is an explanation of the real-time calculation of air conditioning output capacity and the calculation of room load.

[0049] 1. Real-time calculation of air conditioning output capacity:

[0050] First, according to the dry-bulb temperature and relative humidity collected by the temperature and humidity sensors installed at the air inlet and outlet of the indoor unit heat exchanger, the air enthalpy value of the air inlet and the air enthalpy value of the air outlet are calculated respectively; then, according to the air enthalpy value of the air inlet and the air enthalpy value of the air outlet, the real-time unit mass air enthalpy difference under the current working mode of the air conditioner is calculated; finally, according to the real-time unit mass air enthalpy difference under the current working mode of the air conditioner and the air quality per unit time at the air outlet, the real-time output capacity of the air conditioner under the current working mode is calculated. The input parameters required to calculate the output capacity are as follows: Figure 1 As shown, ta.jf is the dry bulb temperature of the air inlet of the air conditioner; is the relative humidity at the air inlet of the air conditioner; ta.cf is the dry bulb temperature at the air outlet of the air conditioner; It is the relative humidity of the indoor air outlet of the air conditioner. In addition, it also includes the internal fan speed rpm. Based on these parameters and the built-in software algorithm, the air conditioner MCU can calculate the real-time output capacity of the air conditioner in the current working mode.

[0051] The specific process is as follows:

[0052] 1. Calculate the saturated vapor pressure Ps of air by dry bulb temperature:

[0053]

[0054] Among them, t a is the dry bulb temperature. When the dry bulb temperature of the air inlet is ta.jf, the saturated steam pressure Ps.jf at the air inlet is calculated by this formula. When the dry bulb temperature of the air inlet and outlet is ta.cf, the saturated steam pressure Ps.cf at the air outlet is calculated by this formula.

[0055] 2. Calculate the moisture content d based on the saturated vapor pressure Ps:

[0056]

[0057] Among them, P a is the air pressure, which is taken according to the standard atmospheric pressure: 101.35 kPa; is the relative humidity, Ps is the saturated vapor pressure; the relative humidity at the air inlet When the saturated steam pressure Ps.jf at the air inlet is calculated by this formula, the air humidity content d.jf at the air inlet is calculated; when the relative humidity at the air inlet and outlet is calculated, When the saturated vapor pressure Ps.cf at the air outlet is taken into account, the air humidity content d.cf at the air outlet is calculated by this formula.

[0058] 3. Calculate the air enthalpy value h according to the moisture content:

[0059] h=1.006t a +d(2501.4+1.86t a )

[0060] When the dry-bulb temperature at the air inlet is ta.jf and the air humidity at the air inlet is d.jf, the air enthalpy value at the air inlet is h.jf; when the dry-bulb temperature at the air inlet and outlet is ta.cf and the air humidity at the air inlet is d.cf, the air enthalpy value at the air outlet is h.cf.

[0061] 4. Calculate the enthalpy difference based on the enthalpy values ​​of the inlet and outlet air:

[0062] During cooling, the air temperature decreases, the enthalpy value at the air inlet is higher than the enthalpy value at the air outlet, and the cooling enthalpy difference Δh.c = h.jf-h.cf.

[0063] During heating, the air temperature rises, the enthalpy value at the air outlet is higher than the enthalpy value at the air inlet, and the heating enthalpy difference Δh.h = h.cf-h.jf.

[0064] The above is the calculation process of enthalpy difference. For example, during the cooling operation, the air inlet temperature and humidity input into the MCU through the temperature and humidity sensor are: dry bulb temperature 28℃, relative humidity 70%, and the air outlet temperature and humidity are: dry bulb temperature 20℃, relative humidity 90%. The enthalpy difference is calculated as follows:

[0065] Substitute the inlet air dry bulb temperature ta=28℃ into the formula:

[0066]

[0067] It can be calculated that the inlet saturated steam pressure Ps = 3782.63Pa.

[0068] Then the inlet air saturated steam pressure Ps = 3782.63Pa, air pressure Pa = 101.35kPa and inlet air relative humidity Substituting into the formula:

[0069]

[0070] The humidity content of the incoming air can be calculated as d = 0.0167 kg / kg.

[0071] Finally, substitute the inlet air dry bulb temperature ta = 28°C and moisture content d = 16.7 g / kg into the formula:

[0072] h=1.006t a +d(2501.4+1.86t a )

[0073] The enthalpy value of the incoming air at this time can be calculated as h.jf = 70.81Kj / Kg.

[0074] Similarly, by repeating the above steps, the outlet air enthalpy value h.cf=54.06Kj / Kg can be calculated.

[0075] At this time, the enthalpy difference of the refrigeration inlet and outlet air Δh.c = h.jf-h.cf = 70.81-54.06 = 16.75Kj / Kg.

[0076] 5. Calculate the air quality per unit time at the air outlet:

[0077] When calculating the air quality per unit time at the air outlet, it is first necessary to determine the specific air volume at the corresponding wind speed level in the air conditioning working mode.

[0078] In an exemplary solution, the specific air volume at each speed of cooling and heating can be accurately calibrated in advance by the enthalpy difference laboratory, for example:

[0079] model Strong Gao Feng Stroke Low wind breeze Refrigeration C C C Cd C Heating HkD Hg Hz Hd H

[0080] The above calibration results are stored in the air conditioner memory, and the MCU calls them according to the actual working mode and current speed gear during the operation of the air conditioner.

[0081] After determining the specific air volume at the corresponding wind speed level in the air-conditioning working mode, the MCU calculates the air quality per unit time at the air outlet based on the product of the determined air volume and the air density corresponding to the dry-bulb temperature at the air outlet.

[0082] For example: The air conditioner is currently working in cooling mode, and the wind speed gear is high wind. According to its pre-calibrated high wind volume in cooling mode, Cg = 1000m 3 / h, the current dry bulb temperature at the air outlet is 20°C, and the corresponding air density ρ = 1.205kg / m 3 ; The air mass per unit time (per second) at the outlet can be calculated as m=1.205*1000 / 3600=0.335kg.

[0083] It should be noted that the air density ρ at different dry-bulb temperatures also needs to be stored in the air conditioner memory, and the MCU is called according to the dry-bulb temperature of the air outlet when calculating the air quality.

[0084] 6. Calculate the real-time output capacity based on the air quality per unit time and enthalpy difference at the air outlet:

[0085] The real-time output capacity of the air conditioner = the air quality per unit time at the outlet * the enthalpy difference between the inlet and outlet air.

[0086] Based on the above-calculated air mass per unit time at the air-conditioning outlet of 0.335 kg and the inlet and outlet air enthalpy difference of 16.75 Kj / Kg, it can be calculated that the air-conditioning output capacity at this time is Q cold = Δh.c*m = 16.75*0.335 = 5.61 KW.

[0087] Similarly, the calculation of heating capacity can also be completed according to the above process.

[0088] 2. Calculation of room load:

[0089] In this section, for the cooling and heating operation process, the room load range under the current indoor and outdoor temperature difference can be iterated based on the real-time output capacity and the direction of room temperature change. Eventually, the temperature change converges, and the real-time output capacity of the air conditioner corresponding to the temperature change convergence is the current room load.

[0090] For example: During cooling, the average output capacity and room temperature changes of a variable frequency air conditioner in different time periods are as follows:

[0091]

[0092] According to the above table, during cooling, t0 is the reference time point, and the room temperature at this time corresponds to T0; within the time period t1, the room temperature continues to change, as shown in the above table. Within the time period t1, the average room temperature decreases by 2°C, which means that the room load is less than the average capacity output Q1 of this period; within the second period t2, the average room temperature increases by 2°C, which means that the room load is greater than the average capacity output Q2 of this period; within the third period t3, the average room temperature remains unchanged, which means that the room load is equal to the average capacity output Q3 of this period; if Q2<Q3<Q1 is satisfied, the iteratively calculated room load is valid.

[0093] For example, when heating, the average output capacity and room temperature changes of a variable frequency air conditioner in different time periods are shown in the following table:

[0094]

[0095] According to the above table, when heating, t0 is the reference time point, and the room temperature at this time corresponds to T0; within the time period t1, the room temperature continues to change, as shown in the above table. Within the time period t1, the average room temperature rises by 2°C, which means that the room load is less than the average capacity output Q1 of this period; within the second period t2, the average room temperature drops by 2°C, which means that the room load is greater than the average capacity output Q2 of this period; within the third period t3, the average room temperature remains unchanged, which means that the room load is equal to the average capacity output Q3 of this period; if Q2<Q3<Q1 is satisfied, the iteratively calculated room load is valid.

[0096] The above-mentioned t0 reference time point is the time when the system reaches stable operation. Implementing the room load calculation from this time point as the starting point can reduce the impact of inaccurate calculations caused by the unstable operation state of the system. In an exemplary scheme, the t0 reference time point can be selected from 15 to 60 minutes after startup, preferably 30 minutes.

[0097] The iteration process time period t should not be set too large or too small, and can generally be selected to be 5 to 30 minutes, preferably 10 minutes.

[0098] Based on the above process, the room load can be calculated dynamically, so that the air conditioner can grasp the room load size and change direction in real time, thereby controlling the variable frequency air conditioner capacity output to adapt to the room load. This can not only keep the variable frequency air conditioner in stable operation, avoid room temperature fluctuations, but also solve the problem of over-adjustment shutdown.

[0099] Finally, it should be noted that the above embodiments are only preferred implementations and are not intended to limit the present invention. It should be pointed out that for those skilled in the art, several modifications, equivalent replacements, improvements, etc. can be made without departing from the scope of the present invention and the scope of protection of the claims, and all of these should be included in the protection scope of the present invention.

Claims

1. A method for calculating room load of a variable frequency air conditioner, applied to a variable frequency air conditioner, wherein the air inlet and air outlet of the indoor unit heat exchanger of the variable frequency air conditioner are respectively provided with temperature and humidity sensors, characterized in that: The method comprises the following steps: During the operation of the air conditioner, the output capacity of the air conditioner is calculated in real time. With the preset time period as the iteration period, the room load range under the current indoor and outdoor temperature difference is iterated according to the real-time calculated output capacity of the air conditioner and the direction of room temperature change. When the room temperature change converges, the corresponding real-time output capacity of the air conditioner is the current room load.

2. A method for calculating room load of a variable frequency air conditioner according to claim 1, characterized in that: The method for calculating the output capacity of the air conditioner in real time comprises: According to the dry-bulb temperature and relative humidity collected by the temperature and humidity sensors installed at the air inlet and air outlet of the indoor unit heat exchanger, the air enthalpy value of the air at the air inlet and the air outlet are calculated respectively; Calculating the real-time air enthalpy difference per unit mass under the current working mode of the air conditioner according to the air inlet air enthalpy value and the air outlet air enthalpy value; The real-time output capacity of the air conditioner in the current working mode is calculated based on the real-time air enthalpy difference per unit mass and the air quality per unit time at the air outlet in the current working mode of the air conditioner.

3. A method for calculating room load of a variable frequency air conditioner as claimed in claim 2, characterized in that: Methods for calculating the air enthalpy value at the air inlet and the air enthalpy value at the air outlet according to the dry-bulb temperature and relative humidity collected by the temperature and humidity sensors arranged at the air inlet and the air outlet of the indoor unit heat exchanger include: Firstly, according to the collected dry bulb temperatures of the air inlet and outlet, the air saturated vapor pressure at the air inlet and outlet is calculated using the air saturated vapor pressure calculation formula; Then, according to the saturated steam pressure of the air at the air inlet and the air outlet and the relative humidity at the air inlet and the air outlet, the moisture content at the air inlet and the air outlet is calculated using the moisture content formula; Next, according to the moisture content at the air inlet and the air outlet, the enthalpy value of the air at the air inlet and the air outlet are calculated using the enthalpy value calculation formula.

4. A method for calculating room load of a variable frequency air conditioner as claimed in claim 2, characterized in that: The method for calculating the real-time unit mass air enthalpy difference in the current working mode of the air conditioner according to the air inlet air enthalpy value and the air outlet air enthalpy value includes: If the current working mode is cooling mode, then: Δh.c=h.jf-h.cf Among them, Δh.c is the real-time unit mass air enthalpy difference in cooling mode; h.jf is the air enthalpy value at the air inlet; h.cf is the air enthalpy value at the air outlet; If the current working mode is heating mode, then: Δh.h=h.cf-h.jf Among them, Δh.h is the real-time unit mass air enthalpy difference in heating mode; h.cf is the air enthalpy value at the air outlet; h.jf is the air enthalpy value at the air inlet.

5. A method for calculating room load of a variable frequency air conditioner as claimed in claim 2, characterized in that: The calculation method of the air quality per unit time at the air outlet includes: Determine the corresponding air density based on the dry-bulb temperature collected by the temperature and humidity sensor installed at the air outlet; Determine the air volume corresponding to the current gear speed of the air conditioner in the current mode; The air quality per unit time at the air outlet is calculated according to the determined corresponding air density and the corresponding air volume at the current gear speed of the air conditioner in the current mode.

6. A method for calculating room load of a variable frequency air conditioner as claimed in claim 5, characterized in that: The method of determining the air volume corresponding to the current gear speed of the air conditioner in the current mode includes: The corresponding air volume at each speed of cooling and heating is calibrated in advance by the enthalpy difference laboratory; When the air conditioner is running, the pre-calibrated corresponding air volume is called according to the current working mode and gear speed.

7. A method for calculating room load of a variable frequency air conditioner according to claim 1, characterized in that: The method of iterating the room load range under the current indoor and outdoor temperature difference with a preset time period as an iteration period and according to the output capacity of the air conditioner and the room temperature change direction calculated in real time includes: If the air conditioner is currently working in cooling mode: If the average room temperature in this cycle is lower than the average room temperature in the previous cycle, it means that the room load is less than the average output capacity of the air conditioner in this cycle; If the average room temperature in this cycle is higher than the average room temperature in the previous cycle, it means that the room load is greater than the average output capacity of the air conditioner in this cycle; If the air conditioner is currently working in heating mode: If the average room temperature in this cycle is lower than the average room temperature in the previous cycle, it means that the room load is greater than the average output capacity of the air conditioner in this cycle; If the average room temperature in this cycle is higher than the average room temperature in the previous cycle, it means that the room load is less than the average output capacity of the air conditioner in this cycle.

8. A method for calculating room load of a variable frequency air conditioner according to claim 1, characterized in that: The room temperature change convergence means that the average room temperature in the current cycle remains unchanged compared with the average room temperature in the previous cycle.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the variable frequency air conditioner room load calculation method according to any one of claims 1 to 8 are implemented.

10. An air conditioning system, comprising a processor and a memory, wherein a computer program is stored in the memory, characterized in that: The processor implements the steps of the variable frequency air conditioner room load calculation method as described in any one of claims 1 to 8 by executing the computer program.

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