Indoor unit system with PTC heater and air speed control method of indoor unit system

Abstract

The invention discloses an indoor unit system with a PTC heater and an air speed control method thereof.The indoor unit system comprises an indoor unit, an air supply pipeline and an air return pipeline, and the indoor unit comprises a heat exchanger, an air supply fan, the PTC heater and a control mechanism; the control mechanism comprises a calibration information storage module, an operation state acquisition module, an operation state judgment module, an operation state adjustment module and an operation state recording module. The wind speed control method comprises the steps of parameter presetting, automatic calibration and dynamic rotation speed adjustment. Through automatic calibration, dynamic resistance coefficient calculation, power feedback control and parameter storage mechanisms, full-automatic optimized operation of the air pipe air supply type air conditioner indoor unit is achieved, and the technical effects cover the multiple aspects of reliability improvement, environmental adaptability enhancement, energy efficiency optimization, fault pre-judgment, maintenance convenience and the like; the method is obviously superior to a traditional technical scheme depending on fixed rotating speed presetting, and has outstanding practical value and market competitiveness.

Description

Technical Field

[0001] The present invention relates to an indoor unit system with a PTC heater and a method for controlling the air speed thereof. Background Art

[0002] For existing ducted air conditioner indoor units, multiple combinations of the operating speeds of the internal fan are set according to the external static pressure conditions during the operation of the indoor unit (such as a static pressure of 0 Pa or a static pressure of 30 Pa). This method often requires manual selection of an appropriate static pressure setting (which can be selected by setting a dip switch on the controller or by using a controller device such as a remote control or a wired controller) to cope with the differences caused by different air supply and return conditions in the actual engineering application environment. By selecting different static pressure conditions, the ducted air conditioner indoor unit can operate under better operating conditions.

[0003] The ultimate goal of static pressure regulation is to make the circulating air volume (air speed) during the operation of the unit reach the design requirements, so that the unit can achieve the target refrigeration or heating effect.

[0004] The method of adjusting the external static pressure by selecting the fan speed can solve the requirements for different external static pressures in different installation environments. However, this method requires manual setting, and there are the following deficiencies in manual setting: 1. It is easy to cause too low air speed (affecting the refrigeration / heating effect) or too high air speed (increasing noise and energy consumption) due to operation errors or omissions; 2. The preset speed at the factory cannot adapt to the dynamic air resistance changes caused by complex duct layouts (such as adding new ducts or flow guiding mechanisms); 3. It lacks the ability to quantitatively evaluate the comprehensive resistance coefficient and is difficult to ensure that the unit operates under the best working conditions. Summary of the Invention

[0005] In view of the above problems, the present invention provides an indoor unit system with a PTC heater and a method for controlling the air speed thereof, effectively solving the problems pointed out in the background art.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An indoor unit system with a PTC heater, comprising an indoor unit, a supply air duct and a return air duct. The supply air duct is connected to the air supply outlet of the indoor unit, and the return air duct is connected to the air return inlet of the indoor unit. The indoor unit includes a heat exchanger, a supply air fan, a PTC heater and a control mechanism. The control mechanism includes a calibration information storage module, an operating state acquisition module, an operating state judgment module, an operating state adjustment module and an operating state recording module. The calibration information storage module is used to store the supply air fan input power information of the indoor unit system preset before leaving the factory under various preset static pressures and preset air speeds. The operating state acquisition module is used to acquire the operating state of the indoor unit system during the calibration operation. The operating state judgment module is used to judge whether the current operating state is reasonable according to the operating state of the indoor unit system acquired during the calibration operation. The operating state adjustment module is used to adjust the operating state of the supply air fan during the calibration operation of the indoor unit system. The operating state recording module is used to record the appropriate operating parameter information of the supply air fan under the current operating conditions after the calibration operation is completed.

[0008] Preferably, the combined resistance coefficient of the supply air duct and the return air duct is S. As S increases, the input power of the PTC heater gradually decreases, and the decreasing rate gradually accelerates as S increases.

[0009] Preferably, during the calibration operation of the PTC heater, the minimum limit power of the PTC heater is N PTC_min , if during the calibration operation at the reference speed R of the supply air fan under the static pressure condition of 30 Pa H30 , and the input power of the PTC heater still does not reach NPTC_min, it can be judged that the indoor unit system cannot operate normally in the current installation environment.

[0010] Preferably, the supply air speed of the supply air fan is v. As v increases, the input power of the PTC heater gradually increases.

[0011] Meanwhile, the present invention also provides a method for controlling the air speed of an indoor unit system with a PTC heater, comprising the following steps:

[0012] 1). Preset parameters:

[0013] Preset the reference speeds of the supply air fan under the static pressure conditions of 0 Pa and 30 Pa, and the three target air speeds under the static pressure conditions of 0 Pa and 30 Pa at the time of leaving the factory, v1: the target air speed of the low air speed gear, v2: the target air speed of the medium air speed gear of the supply air fan, v3: the target air speed of the high air speed gear of the supply air fan;

[0014] 2). Automatic calibration:

[0015] 21) When starting up for the first time or receiving a calibration signal, start the calibration program;

[0016] 22) The air supply fan runs at the reference speed R under the static pressure condition of 0 Pa, and obtain the actual power N H0 ' of the PTC heater; PTC ';

[0017] 23) If N PTC ' is lower than the minimum limit power N PTC_min , the air supply fan switches to the reference speed R of 30 Pa static pressure for recalibration, and N H30 is preset for the system; PTC_min ;

[0018] 24) According to the preset corresponding values of the comprehensive resistance coefficient S and the input power N PTC of the PTC heater, obtain the current comprehensive resistance coefficient S' corresponding to the actual power N PTC ' of the PTC heater. For example, according to Figure 4 the curve relationship diagram of the power N H0 consumed by the PTC heater under the high wind speed R operating condition of the air supply fan at 0 Pa static pressure and the comprehensive resistance coefficient S, the current comprehensive resistance coefficient S' can be obtained according to the actual power N PTC of the PTC heater; PTC ;

[0019] 3) Dynamic speed adjustment:

[0020] 31) Based on the current comprehensive resistance coefficient S' and the target air speed of the air supply fan, use the formula to calculate the target power N of the air supply fan, and drive the air supply fan to operate according to the target power N, where S = S', v is the target air speed of the air supply fan, A is the air outlet area of the indoor unit, A is preset at the factory, ρ is the air density, and η is the efficiency of the air supply fan, and η is preset at the factory;

[0021] 32) Obtain and record the current operating speed R n when the air supply fan operates according to the target power N for subsequent operation. When v = v1, R n is the low wind speed operating speed of the air supply fan. When v = v2, R n is the medium wind speed operating speed of the air supply fan. When v = v3, R n is the high wind speed operating speed of the air supply fan.

[0022] Preferably, the ρ is calculated according to the current indoor ambient temperature T i using the following formula: ρ = 353 / (273 + T i ) m 3 / kg.

[0023] The present invention correlates the power of the PTC heater with the duct resistance coefficient, realizes dynamic calibration through power feedback, and proposes an iterative calculation model based on the resistance coefficient and the target wind speed, breaking through the limitation of traditional fixed-speed presetting, improving the adaptability of the unit to different installation environments, and extending the service life of the equipment.

[0024] Advantages of the present invention:

[0025] 1. Eliminate manual setting errors and improve operation reliability:

[0026] Traditional technologies rely on manual selection of static pressure conditions and fan speeds, which are prone to low wind speeds (affecting cooling / heating effects) or high wind speeds (increasing noise and energy consumption) due to operation errors or omissions. The present invention automatically matches the air resistance parameters of the current installation environment through an automatic calibration program when first starting up or receiving a calibration signal, completely avoiding the potential risks of manual intervention and ensuring that the unit always operates under the best conditions;

[0027] 2. Dynamically adapt to complex duct layouts and enhance environmental adaptability:

[0028] Based on the preset air supply fan speeds and PTC heater power curves under static pressure conditions of 0 Pa and 30 Pa, combined with the actual power N PTC ' of the PTC heater obtained in real time during the calibration process, the system can dynamically calculate the comprehensive resistance coefficient S' of the supply and return air ducts. Based on S', the target wind speeds v1, v2, and v3, the input power N of the air supply fan is dynamically adjusted using a formula to drive the fan to operate according to the input power N and obtain the fan speed. This mechanism can automatically compensate for changes in air resistance caused by newly added ducts, flow guiding mechanisms, or filter blockages, ensuring a stable air supply volume and avoiding the limitations of traditional preset speeds;

[0029] 3. Save energy, reduce noise, and improve the energy efficiency ratio:

[0030] By accurately matching the fan speed with the real-time air resistance conditions, the system always operates with the minimum necessary power. For example, when the resistance coefficient S increases, the power of the PTC heater significantly decreases. At this time, the system automatically reduces the fan speed to avoid ineffective energy consumption and noise caused by too high a speed. Experimental data show that this method can reduce the fan energy consumption by about 15%-20% and reduce the noise by 3-5 decibels;

[0031] 4. Fault prediction and environmental compatibility detection:

[0032] Set the minimum limit power N PTC_min of the PTC heater during the calibration process. If at the reference speed R H30If the power still cannot be reached under such circumstances, the system determines that the current environment is not suitable and issues a warning. This function can avoid damage to the unit caused by incorrect selection or extreme wind resistance in advance and extend the equipment life;

[0033] 5. Intelligent parameter storage and reuse:

[0034] After calibration is completed, the system will adapt the fan speed R of each gear to the current environment n and store it in the control mechanism. The stored parameters are directly called during subsequent operation to ensure consistency. After the user replaces the air duct or filter screen, the manual calibration function can be used to re-adapt to the new working conditions, significantly reducing the maintenance cost;

[0035] 6. Precise air density compensation:

[0036] By obtaining the indoor environment temperature Ti in real time and using the formula to dynamically correct the air density ρ, the accuracy of wind speed control is further improved, especially in an environment with a large temperature difference;

[0037] 7. Through the automatic calibration, dynamic resistance coefficient calculation, power feedback control and parameter storage mechanism, the present invention realizes the full-automatic optimized operation of the indoor unit of the air duct air conditioner. Its technical effects cover multiple aspects such as improved reliability, enhanced environmental adaptability, energy efficiency optimization, fault prediction and maintenance convenience, etc., which are significantly superior to the traditional technical solution relying on fixed speed preset, and have outstanding practical value and market competitiveness. Brief Description of the Drawings

[0038] Figure 1 It is a schematic structural diagram of the indoor unit system of the present invention;

[0039] Figure 2 It is a schematic structural diagram of the control mechanism;

[0040] Figure 3 It is a schematic logic diagram of the control method of the present invention;

[0041] Figure 4 It is a curve relationship diagram of the power NPTC consumed by the PTC heater of the indoor unit system involved in the present invention under the high wind speed RH0 operation condition of the air supply fan at 0 Pa static pressure and the comprehensive resistance coefficient S of the air supply and return air pipe networks;

[0042] Figure 5 It is a curve relationship diagram of the PTC heater and the air supply fan wind speed v of the indoor unit system involved in the present invention. Detailed Embodiment

[0043] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0044] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0045] In addition, in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0046] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0047] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified or limited, the first feature being "above" or "below" the second feature may include direct contact between the first and second features, or may include indirect contact between the first and second features through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0049] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0050] Embodiment 1

[0051] As Figure 1-2 shown, an indoor unit system with a PTC heater includes an indoor unit 10, a supply air duct 30 and a return air duct 20. The supply air duct 30 is connected to the supply air outlet of the indoor unit 10, and the return air duct 20 is connected to the return air inlet of the indoor unit 10. The indoor unit 10 includes a heat exchanger 11, a supply air fan 12, a PTC heater 13 and a control mechanism 14. The control mechanism 14 includes a calibration information storage module 141, an operating state acquisition module 142, an operating state judgment module 143, an operating state adjustment module 144 and an operating state recording module 145. The calibration information storage module 141 is used to store the supply air fan input power information of the indoor unit system preset before leaving the factory under various preset static pressures and preset air speeds. The operating state acquisition module 142 is used to acquire the operating state of the indoor unit system during the calibration operation. The operating state judgment module 143 is used to judge whether the current operating state is reasonable according to the acquired operating state of the indoor unit system during the calibration operation. The operating state adjustment module 144 is used to adjust the operating state of the supply air fan during the calibration operation of the indoor unit system. The operating state recording module 145 is used to record the appropriate operating parameter information of the supply air fan under the current operating conditions after the calibration operation is completed.

[0052] The combined resistance coefficient of the supply air duct 30 and the return air duct 20 is S. As S increases, the input power of the PTC heater 13 gradually decreases, and the decreasing rate gradually accelerates as S increases.

[0053] During the calibration operation of the PTC heater 13, the minimum limit power of the PTC heater 13 is N PTC_min , if the reference speed R of the supply air fan 12 under the static pressure condition of 30 Pa H30When the input power of the PTC heater 13 still fails to reach NPTC_min during the calibration operation, it can be determined that the indoor unit system cannot operate normally in the current installation environment.

[0054] The air supply speed of the air supply fan 12 is v. As v increases, the input power of the PTC heater 13 gradually increases.

[0055] Meanwhile, the present invention also provides a method for controlling the air speed of an indoor unit system with a PTC heater, including the following steps:

[0056] 1). Preset parameters:

[0057] When leaving the factory, the reference rotation speed of the air supply fan under two static pressure conditions of 0 Pa and 30 Pa, and the three - gear target air speeds under two static pressure conditions of 0 Pa and 30 Pa are preset. v1: the target air speed of the low - wind gear, v2: the target air speed of the medium - wind gear of the air supply fan, v3: the target air speed of the high - wind gear of the air supply fan;

[0058] 2). Automatic calibration:

[0059] 21). When starting up for the first time or receiving a calibration signal, start the calibration program;

[0060] 22). The air supply fan runs at the reference rotation speed R under the static pressure condition of 0 Pa, H0 and obtain the actual power N PTC ' of the PTC heater;

[0061] 23). If N PTC ' is lower than the minimum limit power N PTC_min , the air supply fan switches to the reference rotation speed R of 30 Pa static pressure for re - calibration, and N H30 is preset for the system; PTC_min

[0062] 24). According to the corresponding values of the preset comprehensive resistance coefficient S and the input power N PTC of the PTC heater, obtain the current comprehensive resistance coefficient S' corresponding to the actual power N PTC ' of the PTC heater. For example, according to Figure 4 the curve relationship diagram of the power N H0 consumed by the PTC heater under the high - wind rotation speed R of the air supply fan under the 0 Pa static pressure condition and the comprehensive resistance coefficient S, the current comprehensive resistance coefficient S' can be obtained according to the actual power N PTC of the PTC heater; PTC

[0063]

[0064] 3). Dynamic rotation speed adjustment:

[0064] 31). Based on the current comprehensive resistance coefficient S' and the target air speed of the air supply fan, use the formula Calculate the target power N of the air supply fan and drive the air supply fan to operate at the target power N, where S = S', v is the target air velocity of the air supply fan, A is the air outlet area of the indoor unit, A is preset at the factory, ρ is the air density, and ρ is based on the current indoor environmental temperature T i , and use the following formula for calculation:

[0065] ρ = 353 / (273 + T i ) m 3 / kg, η is the efficiency of the air supply fan, and η is preset at the factory;

[0066] 32), Obtain and record the current operating speed R of the air supply fan when it operates at the target power N n , for subsequent operation. When v = v1, R n is the operating speed of the low wind gear of the air supply fan. When v = v2, R n is the operating speed of the medium wind gear of the air supply fan. When v = v3, R n is the operating speed of the high wind gear of the air supply fan.

[0067] Figure 3 Schematically shows the logic diagram of the control method of the present invention. The specific control logic is as follows:

[0068] Step S1: Start the program, and then enter step S2;

[0069] Step S2: Obtain historical operating information, and then enter step S3;

[0070] Step S3: Judge whether the indoor unit is operating for the first time. If the indoor unit is operating for the first time, enter step S4; otherwise, enter step S20;

[0071] Step S4: Enter the calibration operation stage, the PTC heater is put into operation, and then enter step S5;

[0072] Step S5: Let the rotation speed R of the air supply fan be the reference speed R of the air supply fan under the condition of 0 Pa static pressure H0 , and then enter step S6;

[0073] Step S6: Obtain the actual input power N PTC ’ of the PTC heater, and then enter step S7;

[0074] Step S7: Judge whether the actual input power N PTC ’ of the PTC heater reaches a stable value. If the actual input power N PTC ’ of the PTC heater reaches a stable value, enter step S8; otherwise, enter step S6;

[0075] Step S8: Compare the actual input power N of the PTC heater PTC ’ with the minimum limit power N of the PTC heater PTC _min. If N PTC ’ < N PTC_min then proceed to Step S9; otherwise, proceed to Step S12.

[0076] Step S9: Determine whether the current rotational speed R of the air supply fan is the reference rotational speed R of the air supply fan under a static pressure of 30 Pa H30 . If R = R H30 then proceed to Step S10; otherwise, proceed to Step S11.

[0077] Step S10: Determine that the unit is not suitable for the current environment, provide a warning message to the user, and then proceed to Step S21.

[0078] Step S11: Set the rotational speed R of the air supply fan to the reference rotational speed R of the air supply fan under a static pressure of 30 Pa H30 , and then proceed to Step S6.

[0079] Step S12: Stop the operation of the PTC heater. Based on the actual input power N PTC ’ of the obtained PTC heater, combined with Figure 4 obtain the current comprehensive pipeline resistance coefficient S’. Set the comprehensive pipeline resistance coefficient S = S’, and then proceed to Step S13.

[0080] Step S13: Obtain the current indoor environmental temperature T i , and calculate the air density ρ under the current temperature condition (for a standard atmospheric pressure, ρ = 353 / (273 + T i ) m i / kg). Obtain the air supply outlet area A and the efficiency η of the air supply fan, and then proceed to Step S14. 3 Step S14: Set n = 1, and then proceed to Step S15.

[0081] Step S15: Obtain the preset target air supply wind speed v

[0082] . Set v = v n , and then proceed to Step S16. n Step S16: Calculate the target power N of the air supply fan according to the formula

[0083] . The air supply fan operates according to the target power N, and then proceed to Step S17. Step S17: Obtain and record the current rotational speed R of the fan

[0084] . Then proceed to Step S18. n Step S18:

[0085] Step S18: Determine whether the statistical parameter n is equal to 3. If so, proceed to Step S21; otherwise, proceed to Step S19;

[0086] Step S19: Let n = n + 1, and then proceed to Step S15;

[0087] Step S20: Determine whether the air conditioner has received a manual calibration signal. If a manual calibration signal is received, proceed to Step S4; otherwise, proceed to Step S21;

[0088] Step S21: End the program.

[0089] Figure 4 is the curve relationship diagram of the power N consumed by the PTC heater of the indoor unit system involved in the present invention under the high wind speed R at the static pressure of 0 Pa of the air supply fan H0 under the operating condition, as the comprehensive resistance coefficient S of the air supply and return air pipe networks gradually increases, the input power of the PTC heater gradually decreases, and the decreasing rate gradually accelerates with the increase of the comprehensive resistance coefficient S. During the calibration operation, there is a minimum limit power N of the PTC heater PTC , if during the calibration operation at the reference speed R PTC_min of the air supply fan under the static pressure condition of 30 Pa, the input power of the PTC heater still fails to reach N H30 , it can be determined that the unit cannot operate normally in the current installation environment; PTC_min

[0090] Figure 5 is the curve relationship diagram of the PTC heater of the indoor unit system involved in the present invention and the air supply fan speed v. As the air supply speed v increases, the input power of the PTC heater gradually increases.

[0091] Formula The derivation process is as follows:

[0092]

[0093] In Equation 1, the definitions of each parameter are as follows:

[0094] N: Power consumed by the fan, W;

[0095] Q: Air supply volume of the fan, m 3 / h;

[0096] p: Fan air pressure, pa;

[0097] η: Fan efficiency, this parameter is data associated with the fan speed and is a factory preset value.

[0098] p​st = SQ 2 (Equation 2)

[0099] In Equation 2, the definitions of the parameters are as follows:

[0100] p st : Static pressure of air supply (resistance of air supply duct), Pa;

[0101] S: Comprehensive resistance coefficient of the pipe network (this number is only related to the air duct and has nothing to do with the wind speed);

[0102] Q: Total air volume, m 3 / h.

[0103]

[0104] In Equation 3, the definitions of the parameters are as follows:

[0105] p d : Dynamic pressure of air supply, Pa;

[0106] ρ: Air density. For example, the air density under normal temperature and pressure is 1.2 kg / m 3 ;

[0107] v: Outlet air velocity (there are preset values for each air damper), m / s.

[0108] p = p st + p d (Equation 4)

[0109] In Equation 4, the definitions of the parameters are as follows:

[0110] p: Fan air pressure (the same as Equation 1), Pa;

[0111] Combining Equation 2, Equation 3, and Equation 4, we get Equation 5.

[0112]

[0113] Combining Equation 1 and Equation 5, we get Equation 6:

[0114]

[0115] Since the air supply volume Q has the relationship with the air supply velocity v and the air supply outlet area A as shown in Equation 7:

[0116] Q = 3600·v·A (Equation 7)

[0117] Combining Equation 6 and Equation 7, we get Equation 8:

[0118]

[0119] For a given indoor unit of an air duct type air conditioner, the area A of the air supply outlet is often fixed, the operating efficiency η of the air supply fan is often known, and the air density ρ under each atmospheric pressure condition is only related to the air temperature. Therefore, when the value of the comprehensive resistance coefficient S of the pipe network and the target air supply speed v are obtained, the target input power N of the fan can be directly calculated according to Equation 8, and the air supply fan can be operated under the target conditions by controlling the target input power N of the fan.

[0120] Symbol Explanation:

[0121] T i : Indoor environmental temperature, °C;

[0122] N’: Actual operating power of the air supply fan, W;

[0123] N: Target power of the air supply fan, W;

[0124] N PTC ’: Actual input power of the PTC auxiliary heater, W;

[0125] N PTC_min : Minimum limit power of the PTC auxiliary heater, preset value, such as N PTC_min Preset to 500 W;

[0126] R H0 : Reference speed of the air supply fan under 0 Pa static pressure condition, preset value, such as R H0 Preset to 800 rpm;

[0127] R H30 : Reference speed of the air supply fan under 30 Pa static pressure condition, preset value, such as R H30 Preset to 1100 rpm;

[0128] v: Calculated wind speed value, m / s;

[0129] v n : Target air supply speed of the air supply fan, preset value, n takes the value of 1 or 2 or 3; n = 1 is marked as the low gear target air supply speed, such as v1 = 2 m / s; n = 2 is marked as the medium gear target air supply speed, such as v2 = 3 m / s; n = 3 is marked as the high gear target air supply speed, such as v3 = 4 m / s;

[0130] R n : Actual speed of the air supply fan under the current installation conditions, n takes the value of 1 or 2 or 3; n = 1 is marked as the low gear speed, n = 2 is marked as the medium gear speed, n = 3 is marked as the high gear speed;

[0131] R’: Actual speed of the air supply fan, rpm.

[0132] Finally, it should be noted that the above-listed are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and there can be many variations. All variations that can be directly derived or associated by those of ordinary skill in the art from the disclosed content of the present invention should be considered as within the protection scope of the present invention.

Claims

1. An indoor unit system with a PTC heater, characterized in that, It includes an indoor unit (10), a supply air duct (30) and a return air duct (20). The supply air duct (30) is connected to the air supply outlet of the indoor unit (10), and the return air duct (20) is connected to the air return inlet of the indoor unit (10). The indoor unit (10) includes a heat exchanger (11), a supply air fan (12), a PTC heater (13) and a control mechanism (14). The control mechanism (14) includes a calibration information storage module (141), an operating state acquisition module (142), an operating state judgment module (143), an operating state adjustment module (144) and an operating state recording module (145). The calibration information storage module (141) is used to store the supply air fan input power information of the indoor unit system preset before leaving the factory under various preset static pressures and preset air speeds. The operating state acquisition module (142) is used to acquire the operating state of the indoor unit system during the calibration operation. The operating state judgment module (143) is used to judge whether the current operating state is reasonable according to the acquired operating state of the indoor unit system during the calibration operation. The operating state adjustment module (144) is used to adjust the operating state of the supply air fan during the calibration operation of the indoor unit system. The operating state recording module (145) is used to record the appropriate operating parameter information of the supply air fan under the current operating conditions after the calibration operation is completed.

2. The indoor unit system with a PTC heater according to claim 1, characterized in that The combined resistance coefficient of the supply air duct (30) and the return air duct (20) is S. As S increases, the input power of the PTC heater (13) gradually decreases, and the decreasing rate gradually accelerates as S increases.

3. The indoor unit system with a PTC heater according to claim 1, characterized in that, During the calibration operation of the described PTC heater (13), the minimum limiting power of the PTC heater (13) is N PTC_min , if during the calibration operation at the reference speed R of the air supply fan (12) under a static pressure condition of 30 Pa H30 , and the input power of the PTC heater (13) still fails to reach NPTC_min, it can be determined that the indoor unit system cannot operate normally in the current installation environment.

4. The indoor unit system with a PTC heater according to claim 1, characterized in that, The air supply speed of the supply air fan (12) is v. As v increases, the input power of the PTC heater (13) gradually increases.

5. The air volume control method of the indoor unit system according to any one of claims 1-4, characterized in that, It includes the following steps: 1). Preset parameters: When leaving the factory, preset the reference speed of the supply air fan under two static pressure conditions of 0 Pa and 30 Pa, and the three-stage target air speeds under two static pressure conditions of 0 Pa and 30 Pa, v1: the target air speed of the low air volume gear, v2: the target air speed of the medium air volume gear of the supply air fan, v3: the target air speed of the high air volume gear of the supply air fan; 2). Automatic calibration: 21). When starting up for the first time or receiving a calibration signal, start the calibration program; 22) The reference speed R of the air supply fan under the static pressure condition of 0 Pa H0 operates to obtain the actual power N PTC ' of the PTC heater; 23) If N PTC is lower than the minimum limit power N PTC_min , the air supply fan switches to the 30 Pa static pressure reference speed R H30 for recalibration, and N PTC_min is preset for the system; 24). According to the corresponding values of the preset combined resistance coefficient S and the input power NPTC of the PTC heater, obtain the current combined resistance coefficient S' corresponding to the actual power NPTC' of the PTC heater; 3). Dynamic speed adjustment: 31) Based on the current comprehensive resistance coefficient S' and the target wind speed of the air supply fan, use the formula to calculate the target power N of the air supply fan, and drive the air supply fan to operate at the target power N, where S = S', v is the target wind speed of the air supply fan, A is the air supply port area of the indoor unit, A is preset at the factory, ρ is the air density, η is the efficiency of the air supply fan, and η is preset at the factory; 32), obtain and record the current operating speed R of the air supply fan when it operates at the target power N n , for subsequent operation. When v = v1, R n is the low-speed operation speed of the air supply fan. When v = v2, R n is the medium-speed operation speed of the air supply fan. When v = v3, R n is the high-speed operation speed of the air supply fan.

6. The method for controlling the wind speed of an indoor unit system according to claim 5, characterized in that, The described ρ is based on the current indoor environmental temperature T i , and is calculated using the following formula: ρ = 353 / (273 + T i ) m 3 / kg.

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