A starting control method of an air source heat pump variable frequency compressor

Abstract

A kind of starting control method of air source heat pump variable frequency compressor, comprising the following steps: step one, heat pump is powered on, enter step two;Step two, the central controller of heat pump count n=0, n is the number of current sampling period, enter step three;Step three, the variable frequency compressor of heat pump starts to work operation, enter step four;Step four, central controller assigns the calculation result of n+1 to n, enter step five;Step five, central controller calculates the current temperature difference value e (n) between preset temperature value Ts and the measured temperature value Tc of current sampling time according to user input preset temperature value Ts.This application first uses incremental PID to calculate the frequency adjustment amount ΔF (n) in single sampling period Δt, then carries out double-layer limiting, i.e., limiting the frequency adjustment amount ΔF (n) to the frequency limiting of frequency increasing or frequency decreasing, finally obtains reasonable actual target frequency value.This application has the characteristics of stable and reliable operation.

Description

Technical Field

[0001] This invention relates to an air source heat pump, and more particularly to a start-up control method for an air source heat pump inverter compressor. Background Technology

[0002] When the frequency of a variable frequency compressor starts too high or the frequency increases too quickly, the following problems may occur: 1) The internal scroll or rotor, bearings, and crankshaft of the variable frequency compressor may experience significant instantaneous stress before the lubricating oil has fully established an oil film. This can easily lead to wear, increased bearing clearance, motor rubbing, abnormal compressor noise, and bearing seizure. 2) When the motor of the variable frequency compressor accelerates from a standstill to its rated speed, it generates a huge instantaneous starting torque. Typically, the starting torque is 2-5 times the normal operating torque. This starting torque is transmitted through the compressor's motor... The mechanical structure transmits vibrations throughout the heat pump, which can easily lead to loosening of the fixing bolts of the heat pump base, fatigue of the heat pump pipeline, and even resonance in the pipeline, thus exacerbating the vibration problem; 3) The inrush current at the moment of startup will cause the motor to generate obvious electromagnetic vibration and electromagnetic noise; severe mechanical vibration directly generates mechanical noise; sudden start / stop of the compressor will cause a sharp change in refrigerant flow and pressure, thereby generating fluid noise such as liquid slugging and surge in the pipeline and valves of the heat pump system; 4) During the high-frequency start-up process of the heat pump, it is easy to trigger a series of problems such as overload of the variable frequency compressor, excessively high exhaust temperature, excessive current, and module overheating. Summary of the Invention

[0003] The purpose of this invention is to provide a stable and reliable start-up control method for an air source heat pump variable frequency compressor, in order to overcome the shortcomings of the prior art.

[0004] A start-up control method for an air source heat pump variable frequency compressor designed for this purpose is characterized by including the following steps:

[0005] Step 1: Power on the heat pump, then proceed to Step 2;

[0006] Step 2: The heat pump's central controller count n=0, where n is the number of the current sampling period. Proceed to Step 3.

[0007] Step 3: The heat pump's inverter compressor starts working and running, proceeding to Step 4;

[0008] Step four: The central controller assigns the calculation result of n+1 to n, and proceeds to step five;

[0009] Step 5: The central controller calculates the current temperature difference e(n) between the preset temperature value Ts input by the user and the measured temperature value Tc at the current sampling time.

[0010] In heating mode, e(n) = Ts - Tc; in cooling mode, e(n) = Tc - Ts; proceed to step six.

[0011] Where e(n) is in °C, e(0) = 0, and e(-1) = 0;

[0012] Where e(n) is in °C, e(0) = 0, and e(-1) = 0;

[0013] Step 6: The central controller calculates the frequency adjustment ΔF(n) within a single sampling period Δt, which is ΔF(n) = Kp*[e(n)-e(n-1)] + Ki*e(n)*Δt + Kd*[e(n)-2*e(n-1)+e(n-2)] / Δt, and then proceeds to step 7;

[0014] The unit of ΔF(n) is Hz;

[0015] Kp is a proportional coefficient used to determine the speed of adjustment. The unit of Kp is Hz / ℃, and the value range of Kp is 1.5 to 15.

[0016] Ki is the integral coefficient used to eliminate steady-state temperature deviation. The unit of Ki is Hz / (°C·s), and the value of Ki ranges from 0.01 to 0.5.

[0017] Kd is a differential coefficient used to suppress temperature overshoot and predict temperature change trends. The unit of Kd is Hz.s / ℃, and the value of Kd ranges from 0.5 to 8.

[0018] Step 7: The central controller determines whether ΔF(n) > Rup is true. If it is true, proceed to step 10; otherwise, proceed to step 8.

[0019] Where Rup is the upper limit of frequency increase within a single sampling period Δt;

[0020] Step 8: The central controller determines whether ΔF(n) < -Rdown is true. If it is true, proceed to step 11; otherwise, proceed to step 9.

[0021] Where Rdown is the upper limit of frequency reduction within a single sampling period Δt;

[0022] Step nine, m(n) = ΔF(n), proceed to step twelve, where m(n) is the amplitude limit value;

[0023] Step 10, m(n) = Rup, proceed to step 12;

[0024] Step 11, m(n) = -Rdown, proceed to step 12;

[0025] Step 12: The central controller determines whether n≥2 is true. If it is true, proceed to step 21; otherwise, proceed to step 13.

[0026] Step thirteen: The central controller calculates the actual target frequency value Ft(n) for the first run;

[0027] Given Ft(n) = Ft(n-1) + m(n) and n < 2, proceed to step fourteen; where Ft(0) = 30Hz;

[0028] Step 14: The central controller determines whether Ft(n) > Fmax is true. If it is true, proceed to step 18; otherwise, proceed to step 15.

[0029] Wherein, Fmax is the maximum frequency, and the value of Fmax ranges from 88 to 102 Hz;

[0030] Step 15: The central controller determines whether Ft(n) < Fmin is true. If it is true, proceed to step 19; otherwise, proceed to step 16.

[0031] Wherein, Fmin is the minimum frequency, and the value of Fmin ranges from 28 to 32 Hz;

[0032] Step 16: The central controller determines whether Feco≤Ft(n)≤Fmax is true. If it is true, proceed to step 20; otherwise, proceed to step 17.

[0033] Among them, Feco is the low frequency with the best energy efficiency, and the value of Feco ranges from 38 to 42 Hz;

[0034] Step 17, Ft(n) = Feco, proceed to step 29;

[0035] Step 18, Ft(n) = Fmax, proceed to step 29;

[0036] Step 19, Ft(n) = Fmin, proceed to step 29;

[0037] Step 20: Ft(n) = Ft(n), proceed to step 29;

[0038] Step 21: The central controller calculates the actual target frequency value Fr(n) during the process, which is Fr(n) = Ft(n-1) + ΔF(n) and n ≥ 2. Proceed to step 22.

[0039] Step 22: The central controller determines whether Fr(n) > Fmax is true. If it is true, proceed to step 26; otherwise, proceed to step 23.

[0040] Step 23: The central controller determines whether Fr(n) < Fmin is true. If it is true, proceed to step 27; otherwise, proceed to step 24.

[0041] Step 24: The central controller determines whether Feco≤Fr(n)≤Fmax is true. If it is true, proceed to step 28; otherwise, proceed to step 25.

[0042] Step 25, Fr(n) = Feco, proceed to step 29;

[0043] Step 26, Fr(n) = Fmax, proceed to step 29;

[0044] Step 27, Fr(n) = Fmin, proceed to step 29;

[0045] Step 28, Ft(n) = Fr(n), proceed to step 29;

[0046] Step 29: Continue running to step 4.

[0047] After adopting the above-mentioned technical solution, the variable frequency compressor starts running from a low speed, allowing sufficient time for the internal oil film of the variable frequency compressor to build up, thus avoiding dry friction. The scroll plate, bearings, and crankshaft of the variable frequency compressor will not be subjected to severe impact, greatly reducing the failure rate of the variable frequency compressor and extending its service life. Furthermore, the air source heat pump unit has low vibration and low noise, and piping valves and other components will not become loose or cracked, thereby greatly improving the reliability of the air source heat pump variable frequency compressor during operation. Fault reports will no longer occur frequently during startup, and the probability of overload, overcurrent, high pressure, low pressure, or module overheating problems will be greatly reduced. Moreover, the vicious cycle of "start-up failure → repeated restarts → more prone to failure" will not occur, greatly reducing the maintenance rate.

[0048] This invention first uses incremental PID to calculate the frequency adjustment ΔF(n) within a single sampling period Δt. Then, it performs dual-layer limiting: limiting ΔF(n) to an upper limit for frequency increase or decrease, and limiting Ft(n) or Fr(n) to boundary constraints. Finally, it obtains a reasonable actual target frequency value, including the actual target frequency value Ft(n) for the first run and the actual target frequency value Fr(n) for the process run. It balances stability and adjustment accuracy, enabling the product to avoid triggering fault protections such as high pressure protection, low pressure protection, and high exhaust temperature during startup. The exhaust pressure and intake pressure rise slowly during operation without drastic fluctuations. The refrigerant flow gradually matches, the risk of liquid slugging is low, and the entire air source heat pump system operates smoothly with stable temperature changes.

[0049] In summary, this invention features stable and reliable operation. Attached Figure Description

[0050] Figure 1 This is a control flow diagram of an embodiment of the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] See Figure 1 A start-up control method for an air source heat pump inverter compressor includes the following steps:

[0053] Step 1: Power on the heat pump, then proceed to Step 2;

[0054] Step 2: The heat pump's central controller count n=0, where n is the number of the current sampling period. Proceed to Step 3.

[0055] Step 3: The inverter compressor of the heat pump starts working and running, proceeding to step 4;

[0056] Step four: The central controller assigns the calculation result of n+1 to n, and proceeds to step five;

[0057] Step 5: The central controller calculates the current temperature difference e(n) between the preset temperature value Ts input by the user and the measured temperature value Tc at the current sampling time.

[0058] In heating mode, e(n) = Ts - Tc; in cooling mode, e(n) = Tc - Ts; proceed to step six.

[0059] Where e(n) is in °C, e(0) = 0, and e(-1) = 0;

[0060] In this embodiment, the preset temperature value Ts can be a preset inlet water temperature value, a preset outlet water temperature value, a preset water temperature value in the water tank, or a preset room temperature value, etc.

[0061] Step 6: The central controller calculates the frequency adjustment ΔF(n) within a single sampling period Δt, which is ΔF(n) = Kp*[e(n)-e(n-1)] + Ki*e(n)*Δt + Kd*[e(n)-2*e(n-1)+e(n-2)] / Δt, and then proceeds to step 7;

[0062] The unit of ΔF(n) is Hz.

[0063] In this embodiment, an incremental PID is used to calculate the frequency adjustment ΔF(n) within a single sampling period Δt.

[0064] Kp is a proportional coefficient used to determine the speed of adjustment. The unit of Kp is Hz / ℃, and the value range of Kp is 1.5 to 15.

[0065] Ki is the integral coefficient used to eliminate steady-state temperature deviation. The unit of Ki is Hz / (°C·s), and the value of Ki ranges from 0.01 to 0.5.

[0066] Kd is a differential coefficient used to suppress temperature overshoot and predict temperature change trends. The unit of Kd is Hz.s / ℃, and the value of Kd ranges from 0.5 to 8.

[0067] Step 7: The central controller determines whether ΔF(n) > Rup is true. If it is true, proceed to step 10; otherwise, proceed to step 8.

[0068] Where Rup is the upper limit of frequency increase within a single sampling period Δt;

[0069] Step 8: The central controller determines whether ΔF(n) < -Rdown is true. If it is true, proceed to step 11; otherwise, proceed to step 9.

[0070] Where Rdown is the upper limit of frequency reduction within a single sampling period Δt;

[0071] Step nine, m(n) = ΔF(n), proceed to step twelve, where m(n) is the amplitude limit value.

[0072] In this embodiment, by setting the limiting value m(n), the sudden load changes of the variable frequency compressor can be effectively avoided, and smooth and continuous adjustment can be achieved.

[0073] Step 10, m(n) = Rup, proceed to step 12;

[0074] Step 11, m(n) = -Rdown, proceed to step 12;

[0075] Step 12: The central controller determines whether n≥2 is true. If it is true, proceed to step 21; otherwise, proceed to step 13.

[0076] Step thirteen: The central controller calculates the actual target frequency value Ft(n) for the first run;

[0077] Given Ft(n) = Ft(n-1) + m(n) and n < 2, proceed to step fourteen; where Ft(0) = 30Hz;

[0078] Step 14: The central controller determines whether Ft(n) > Fmax is true. If it is true, proceed to step 18; otherwise, proceed to step 15.

[0079] Wherein, Fmax is the maximum frequency, and the value of Fmax ranges from 88 to 102 Hz;

[0080] Step 15: The central controller determines whether Ft(n) < Fmin is true. If it is true, proceed to step 19; otherwise, proceed to step 16.

[0081] Wherein, Fmin is the minimum frequency, and the value of Fmin ranges from 28 to 32 Hz;

[0082] Step 16: The central controller determines whether Feco≤Ft(n)≤Fmax is true. If it is true, proceed to step 20; otherwise, proceed to step 17.

[0083] Among them, Feco is the low frequency with the best energy efficiency, and the value of Feco ranges from 38 to 42 Hz;

[0084] Step 17, Ft(n) = Feco, proceed to step 29;

[0085] In this embodiment, by step fourteen to step seventeen, the calculated actual target frequency value Ft(n) for the first run is subject to boundary constraints, which effectively avoids sudden load changes in the variable frequency compressor and achieves smooth and continuous adjustment.

[0086] Step 18, Ft(n) = Fmax, proceed to step 29;

[0087] Step 19, Ft(n) = Fmin, proceed to step 29;

[0088] Step 20: Ft(n) = Ft(n), proceed to step 29;

[0089] Step 21: The central controller calculates the actual target frequency value Fr(n) during the process, which is Fr(n) = Ft(n-1) + ΔF(n) and n ≥ 2. Proceed to step 22.

[0090] Step 22: The central controller determines whether Fr(n) > Fmax is true. If it is true, proceed to step 26; otherwise, proceed to step 23.

[0091] Step 23: The central controller determines whether Fr(n) < Fmin is true. If it is true, proceed to step 27; otherwise, proceed to step 24.

[0092] Step 24: The central controller determines whether Feco≤Fr(n)≤Fmax is true. If it is true, proceed to step 28; otherwise, proceed to step 25.

[0093] Step 25, Fr(n) = Feco, proceed to step 29;

[0094] Step 26, Fr(n) = Fmax, proceed to step 29;

[0095] Step 27, Fr(n) = Fmin, proceed to step 29;

[0096] Step 28, Ft(n) = Fr(n), proceed to step 29;

[0097] Step 29: Continue running to step 4.

[0098] First Application Example

[0099] Heating mode

[0100] The user presets the room temperature to Ts = 22℃. The heat pump's central controller has the following presets: proportional coefficient Kp = 6Hz / ℃, integral coefficient Ki = 0.15Hz / (℃.s), derivative coefficient Kd = 3Hz.s / ℃; sampling period Δt = 10s; the frequency boundaries of the heat pump's variable frequency compressor are: maximum frequency Fmax = 100Hz, minimum frequency Fmin = 30Hz, optimal energy efficiency low frequency Feco = 40Hz, upper limit of frequency increase within a single sampling period Δt Rup = 15Hz; upper limit of frequency decrease within a single sampling period Δt Rdown = 20Hz. Ft(0) = 30Hz; e(0) = 0℃, e(-1) = 0℃.

[0101] The heat pump was started and operated in heating mode. The first sample was taken after the first sampling cycle Δt=10s. The measured temperature of the room was Tc=19℃.

[0102] Step four: The central controller assigns the calculation result of n+1 to n, so n=1, and proceeds to step five;

[0103] Step 5: The central controller calculates the current temperature difference e(1) between the preset temperature value Ts input by the user and the measured temperature value Tc at the current sampling time.

[0104] In heating mode, e(n) = Ts - Tc, therefore, e(1) = Ts - Tc = 22 - 19 = 3℃.

[0105] In step six, the central controller calculates the frequency adjustment ΔF(1) within a single sampling period Δt, which is ΔF(1) = Kp*[e(1) - e(1-1)] + Ki*e(1)*Δt + Kd*[e(1) - 2*e(1-1) + e(1-2)] / Δt

[0106] =6*[3-0]+0.15*3*10+3*[3-2*0+0] / 10

[0107] =18+4.5+0.9

[0108] =23.4Hz;

[0109] Step 7: The central controller determines that ΔF(1) = 23.4Hz > Rup = 15Hz is true, and proceeds to step 10.

[0110] Limiting value m(1) = Rup = 15Hz, proceed to step 12;

[0111] The limiting value m(1) constrains ΔF(1), forcibly limiting ΔF(1) to the range of ± Rup / to ± Rdown, thereby ensuring that the variable frequency compressor accelerates slowly from low speed, allowing sufficient time for the oil film to build up, avoiding dry friction and mechanical shock, and extending the compressor's life.

[0112] Step 12: The central controller determines that n=1≥2 is not true, and proceeds to step 13;

[0113] Step 13: The central controller calculates the actual target frequency value Ft(1) for the first run;

[0114] We have Ft(1) = Ft(1-1) + m(1) = Ft(0) + m(1) = 30 + 15 = 45 Hz. Proceed to step fourteen.

[0115] Step fourteen: The central controller determines that Ft(1) = 45Hz > Fmax = 100Hz is not true, and proceeds to step fifteen.

[0116] Step 15: The central controller determines that Ft(1) = 45Hz < Fmin = 30Hz is not true, and proceeds to step 16;

[0117] Step 16: The central controller determines that Feco=40Hz≤Ft(1)=45Hz≤Fmax=100Hz is true, and proceeds to step 20.

[0118] Step 20: Ft(1) = Ft(1) = 45Hz. Therefore, the actual target frequency value for the first operation of the variable frequency compressor is Ft(1) = 45Hz. Proceed to step 29.

[0119] Step 29; Continue running to step 4.

[0120] When the air source heat pump inverter compressor starts in heating mode, it starts working at a frequency of Ft(0)=30Hz. After the first sampling period Δt=10s, it works at a frequency of Ft(1)=45Hz, the oil film is established, and the inverter compressor runs smoothly.

[0121] Second Application Example

[0122] Based on the first application example, continue with the current heating mode.

[0123] Step four: After Δt=10s, a second sampling is performed. At this time, n=1+1=2, and the measured temperature value in the room is Tc=20.5℃.

[0124] Step 5, in heating mode, e(n) = Ts - Tc.

[0125] The heat pump's central controller calculates e(2) = Ts - Tc = 22 - 20.5 = 1.5℃.

[0126] Step six, the central controller calculates ΔF(2),

[0127] ΔF(2)=Kp*[e(2)-e(1)]+Ki*e(2)*10+Kd*[e(2)-2*e(1)+e(0)] / 10

[0128] =6*[1.5-3]+0.15*1.5*10+3*[1.5-2*3+0] / 10=-9+2.25-1.35=-8.1Hz,

[0129] Step 7: The central controller determines that ΔF(2) = -8.1Hz > Rup = 15Hz is not true, and proceeds to step 8;

[0130] Step 8: The central controller determines that ΔF(2) = -8.1Hz < -Rdown = -20Hz is not true, and proceeds to step 9;

[0131] Step nine, m(2) = ΔF(2) = -8.1Hz, proceed to step twelve, where m(n) is the limiting value;

[0132] Step 12: The central controller determines that n=2≥2 is true, and proceeds to step 21;

[0133] Step 21: The central controller calculates the actual target frequency value Fr(2) during the process.

[0134] Fr(2)=Ft(2-1)+ΔF(2)=Ft(1)+ΔF(2)=45-8.1=36.9Hz, proceed to step twenty-two;

[0135] Step 22: The central controller determines that Fr(2) = 36.9Hz > Fmax = 100Hz is not true, and proceeds to step 23;

[0136] Step 23: The central controller determines that Fr(2) = 36.9Hz < Fmin = 30Hz is not true, and proceeds to step 14;

[0137] Step 24: The central controller determines that Feco=40Hz≤Fr(2)=36.9Hz≤Fmax=100Hz is not true, and proceeds to step 25;

[0138] Step 25, Fr(2)=Feco=40Hz, proceed to step 29;

[0139] Step 29; Continue running to step 4.

[0140] Therefore, after the second sampling period Δt=10s, the air source heat pump variable frequency compressor operates at a frequency of Fr(2)=40Hz, and the variable frequency compressor runs smoothly.

[0141] The remaining undescribed parts are described in the first application example and will not be repeated here.

[0142] Third Application Example

[0143] Based on the second application example, continue with the current heating mode.

[0144] Step four: After Δt=10s, a third sampling is performed. At this time, n=2+1=3, and the measured temperature value in the room is Tc=22.5℃. Proceed to step five.

[0145] Step 5: The central controller calculates e(3) = Ts - Tc = 22 - 22.5 = -0.5℃, and proceeds to step 6.

[0146] Step six, the central controller calculates ΔF(3), then proceeds to step seven;

[0147] ΔF(3)=Kp*[e(3)-e(2)]+Ki*e(3)*10+Kd*[e(3)-2*e(2)+e(1)] / 10

[0148] =6*[-0.5-1.5]+0.15*(-0.5)*10+3*[-0.5-2*1.5+3] / 10

[0149] =-12-0.75-0.15=-12.9Hz;

[0150] Step 7: The central controller determines that ΔF(3) = -12.9Hz > Rup = 15Hz is not true, and proceeds to step 8;

[0151] Step 8: The central controller determines that ΔF(3) = -8.1Hz < -Rdown = -20Hz is not true, and proceeds to step 9;

[0152] Step nine, m(3) = ΔF(3) = -12.9Hz, proceed to step twelve;

[0153] Step 12: The central controller determines that n=3≥2 is true, and proceeds to step 21;

[0154] Step 21: The central controller calculates the actual target frequency value Fr(3) during the process.

[0155] Fr(3) = Ft(3-1) + ΔF(3) = Ft(2) + ΔF(3) = 40 - 12.9 = 27.1 Hz, proceed to step twenty-two;

[0156] Step 22: The central controller determines that Fr(3) = 27.1Hz > Fmax = 100Hz is not true, and proceeds to step 23;

[0157] Step 23: The central controller determines that Fr(3) = 27.1Hz < Fmin = 30Hz is true, and proceeds to step 17;

[0158] Step 27, Fr(3)=Fmin=30Hz, proceed to step 29;

[0159] Step 29: Continue running to step 4.

[0160] Therefore, after the third sampling period Δt=10s, the air source heat pump variable frequency compressor operates at a frequency of Fr(3)=30Hz, and the variable frequency compressor runs smoothly.

[0161] If a sustained overheating occurs, meaning the measured room temperature Tc > Ts and reaches the shutdown hysteresis threshold, the inverter compressor will be triggered to shut down.

[0162] The shutdown hysteresis threshold can be understood as the minimum frequency Fmin. During operation, when Fr(n) = Fmin occurs for the second time, the variable frequency compressor will stop.

[0163] The remaining undescribed parts are explained in the second application example and will not be repeated here.

[0164] Fourth application example

[0165] Cooling mode

[0166] The user presets the outlet water temperature value to 7℃.

[0167] The heat pump's central controller is preset with the following parameters: proportional coefficient Kp = 5 Hz / ℃, integral coefficient Ki = 0.1 Hz / (℃.s), derivative coefficient Kd = 2 Hz.s / ℃; sampling period Δt = 10 s. The frequency boundaries of the heat pump's variable frequency compressor are: maximum frequency Fmax = 90 Hz, minimum frequency Fmin = 30 Hz, and optimal energy efficiency low frequency Feco = 35 Hz. The upper limit of frequency increase within a single sampling period Δt is Rup = 12 Hz; the upper limit of frequency decrease within a single sampling period Δt is Rdown = 18 Hz. Ft(0) = 30 Hz; e(0) = 0 ℃, e(-1) = 0 ℃.

[0168] Start the heat pump and run it in cooling mode. Step four: when the running time has passed the first sampling period Δt=10s, the first sampling is performed. At this time, n=1+0=1, and the measured temperature value of the outlet water is Tc=12℃. Proceed to step five.

[0169] Step 5, in cooling mode, e(n) = Tc - Ts;

[0170] The central controller calculates e(1) = Tc - Ts = 12 - 7 = 5℃, and proceeds to step six.

[0171] Step six, the central controller calculates ΔF(1), then proceeds to step seven;

[0172] ΔF(1)=Kp*[e(1)-e(0)]+Ki*e(1)*10+Kd*[e(1)-2*e(0)+e(-1)] / 10

[0173] =5*[5-0]+0.1*5*10+2*[5-2*0+0] / 10

[0174] =-25+5+1

[0175] =31Hz;

[0176] Step 7: The central controller determines that ΔF(1) = 31Hz > Rup = 12Hz is true, and proceeds to step 10;

[0177] Step 10, m(1)=Rup=12Hz, proceed to step 12;

[0178] Step 12: The central controller determines that n=1≥2 is not true, and proceeds to step 13;

[0179] Step thirteen: The central controller calculates the actual target frequency value Ft(1) for the first run and proceeds to step fourteen;

[0180] There is Ft(1)=Ft(1-1)+m(1)=Ft(0)+m(1)=30+12=42Hz;

[0181] Step fourteen: The central controller determines that Ft(1)=42>Fmax=90 is not true, and proceeds to step fifteen;

[0182] Step 15: The central controller determines that Ft(1) = 42 < Fmin = 30 is not true, and proceeds to step 16;

[0183] Step 16: When the central controller determines that Feco=35≤Ft(1)=42≤Fmax=100 is true, proceed to step 20.

[0184] Step 20: Ft(1) = Ft(1) = 42Hz, remain unchanged, proceed to step 29;

[0185] Step 29: Continue running to step 4.

[0186] When the air source heat pump inverter compressor starts in cooling mode, it starts working at a frequency of Ft(0)=30Hz. After the first sampling period Δt=10s, it works at a frequency of Ft(1)=42Hz, the oil film is established, and the inverter compressor runs smoothly.

[0187] Fifth Application Example

[0188] Based on the fourth application example, continue with the current cooling mode.

[0189] Step 4: When the running time has passed the second sampling period Δt=10s, the second sampling is performed. At this time, n=1+1=2, and the measured temperature value of the outlet water is Tc=9.5℃. Proceed to Step 5.

[0190] Step 5, in cooling mode, e(n) = Tc - Ts;

[0191] The central controller calculates e(2) = Tc - Ts = 9.5 - 7 = 2.5℃, and proceeds to step six.

[0192] Step six, the central controller calculates ΔF(2), then proceeds to step seven;

[0193] ΔF(2)=Kp*[e(2)-e(1)]+Ki*e(2)*10+Kd*[e(2)-2*e(1)+e(0)] / 10

[0194] =5*[2.5-5]+0.1*2.5*10+2*[2.5-2*5+0] / 10

[0195] =-12.5+2.5-1.5

[0196] =-11.5Hz;

[0197] Step 7: The central controller determines that ΔF(2) = -11.5Hz > Rup = 12Hz is not true, and proceeds to step 8;

[0198] Step 8: The central controller determines that ΔF(2) = -11.5Hz < -Rdown = -18Hz is not true, and proceeds to step 9;

[0199] Step nine, m(2) = ΔF(2) = -11.5Hz, proceed to step twelve;

[0200] Step 12: The central controller determines that n=2≥2 is true, and proceeds to step 21;

[0201] Step 21: The central controller calculates the actual target frequency value Fr(2) during the process.

[0202] Fr(2)=Ft(2-1)+ΔF(2)=Ft(1)+ΔF(2)=42-11.5=30.5Hz, proceed to step twenty-two;

[0203] Step 22: The central controller determines that Fr(2) = 30.5Hz > Fmax = 90Hz is not true, and proceeds to step 23;

[0204] Step 23: The central controller determines that Fr(2) = 30.5Hz < Fmin = 30Hz is not true, and proceeds to step 24;

[0205] Step 24: The central controller determines that Feco=35Hz≤Fr(2)=30.5Hz≤Fmax=90Hz is not true, and proceeds to step 25;

[0206] Step 25, Fr(2)=Feco=35Hz, proceed to step 29;

[0207] Step 29: Continue running to step 4.

[0208] The remaining undescribed parts are described in the fourth application example and will not be repeated here.

[0209] Sixth Application Example

[0210] Based on the fifth application example, continue with the current cooling mode.

[0211] Step 4: When the running time has passed the third sampling cycle Δt=10s, the third sampling is performed. At this time, n=2+1=3, and the measured temperature value of the outlet water is Tc=7.2℃. Proceed to Step 5.

[0212] Step 5, in cooling mode, e(n) = Tc - Ts;

[0213] The central controller calculates e(3) = Tc - Ts = 7.2 - 7 = 0.2℃, and proceeds to step six.

[0214] Step six, the central controller calculates ΔF(3), then proceeds to step seven;

[0215] ΔF(3)=Kp*[e(3)-e(2)]+Ki*e(3)*10+Kd*[e(3)-2*e(2)+e(1)] / 10

[0216] =5*[0.2-2.5]+0.1*0.2*10+2*[0.2-2*2.5+5] / 10

[0217] =-11.5+0.2+0.04

[0218] =-11.26Hz;

[0219] Step 7: The central controller determines that ΔF(3) = -11.26Hz > Rup = 12Hz is not true, and proceeds to step 8;

[0220] Step 8: The central controller determines that ΔF(3) = -11.26Hz < -Rdown = -18Hz is not true, and proceeds to step 9;

[0221] Step nine, m(3) = ΔF(3) = -11.26Hz, proceed to step twelve;

[0222] Step 12: The central controller determines that n=2≥2 is true, and proceeds to step 21;

[0223] Step 21: The central controller calculates the actual target frequency value Fr(3) during the process.

[0224] Fr(3) = Ft(3-1) + ΔF(3) = Ft(2) + ΔF(3) = 35 - 11.26 = 23.74 Hz, proceed to step twenty-two;

[0225] Step 22: The central controller determines that Fr(3) = 23.74Hz > Fmax = 90Hz is not true, and proceeds to step 23;

[0226] Step 23: The central controller determines that Fr(3) = 23.74Hz < Fmin = 30Hz is true, and proceeds to step 27;

[0227] Step 27, Fr(3)=Fmin=30Hz, proceed to step 29;

[0228] Step 29: Continue running to step 4.

[0229] After the third sampling cycle Δt=10s, the air source heat pump variable frequency compressor operates at a frequency of Fr(3)=30Hz, and the variable frequency compressor runs smoothly.

[0230] During operation, the actual target frequency value Fr(3) is already the minimum frequency Fmin=30Hz. If the outlet water temperature continues to decrease and the measured outlet water temperature Tc is lower than the user's preset outlet water temperature value Ts=7℃, the variable frequency compressor will stop when Fr(n)=Fmin occurs again during subsequent operation.

[0231] If the outlet water temperature subsequently rises, the central controller will fine-tune Fr(n) according to the above method to maintain the water temperature fluctuating slightly around the set value.

[0232] The remaining undescribed parts are described in the fifth application example and will not be repeated here.

[0233] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0234] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A start-up control method for an air source heat pump variable frequency compressor, characterized in that: Includes the following steps: Step 1: Power on the heat pump, then proceed to Step 2; Step 2: The heat pump's central controller count n=0, where n is the number of the current sampling period. Proceed to Step 3. Step 3: The heat pump's inverter compressor starts working and running, proceeding to Step 4; Step four: The central controller assigns the calculation result of n+1 to n, and proceeds to step five; Step 5: The central controller calculates the current temperature difference e(n) between the preset temperature value Ts input by the user and the measured temperature value Tc at the current sampling time. In heating mode, e(n) = Ts - Tc; in cooling mode, e(n) = Tc - Ts; proceed to step six. Where e(n) is in °C, e(0) = 0, and e(-1) = 0; Step 6: The central controller calculates the frequency adjustment ΔF(n) within a single sampling period Δt, which is ΔF(n) = Kp*[e(n)-e(n-1)] + Ki*e(n)*Δt + Kd*[e(n)-2*e(n-1)+e(n-2)] / Δt, and then proceeds to step 7; The unit of ΔF(n) is Hz; Kp is a proportional coefficient used to determine the speed of adjustment. The unit of Kp is Hz / ℃, and the value range of Kp is 1.5 to 15. Ki is the integral coefficient used to eliminate steady-state temperature deviation. The unit of Ki is Hz / (°C·s), and the value of Ki ranges from 0.01 to 0.

5. Kd is a differential coefficient used to suppress temperature overshoot and predict temperature change trends. The unit of Kd is Hz.s / ℃, and the value of Kd ranges from 0.5 to 8. Step 7: The central controller determines whether ΔF(n) > Rup is true. If it is true, proceed to step 10; otherwise, proceed to step 8. Where Rup is the upper limit of frequency increase within a single sampling period Δt; Step 8: The central controller determines whether ΔF(n) < -Rdown is true. If it is true, proceed to step 11; otherwise, proceed to step 9. Where Rdown is the upper limit of frequency reduction within a single sampling period Δt; Step nine, m(n) = ΔF(n), proceed to step twelve, where m(n) is the amplitude limit value; Step 10, m(n) = Rup, proceed to step 12; Step 11, m(n) = -Rdown, proceed to step 12; Step 12: The central controller determines whether n≥2 is true. If it is true, proceed to step 21; otherwise, proceed to step 13. Step thirteen: The central controller calculates the actual target frequency value Ft(n) for the first run; Given Ft(n) = Ft(n-1) + m(n) and n < 2, proceed to step fourteen; where Ft(0) = 30Hz; Step 14: The central controller determines whether Ft(n) > Fmax is true. If it is true, proceed to step 18; otherwise, proceed to step 15. Wherein, Fmax is the maximum frequency, and the value of Fmax ranges from 88 to 102 Hz; Step 15: The central controller determines whether Ft(n) < Fmin is true. If it is true, proceed to step 19; otherwise, proceed to step 16. Wherein, Fmin is the minimum frequency, and the value of Fmin ranges from 28 to 32 Hz; Step 16: The central controller determines whether Feco≤Ft(n)≤Fmax is true. If it is true, proceed to step 20; otherwise, proceed to step 17. Among them, Feco is the low frequency with the best energy efficiency, and the value of Feco ranges from 38 to 42 Hz; Step 17, Ft(n) = Feco, proceed to step 29; Step 18, Ft(n) = Fmax, proceed to step 29; Step 19, Ft(n) = Fmin, proceed to step 29; Step 20: Ft(n) = Ft(n), proceed to step 29; Step 21: The central controller calculates the actual target frequency value Fr(n) during the process, which is Fr(n) = Ft(n-1) + ΔF(n) and n ≥ 2. Proceed to step 22. Step 22: The central controller determines whether Fr(n) > Fmax is true. If it is true, proceed to step 26; otherwise, proceed to step 23. Step 23: The central controller determines whether Fr(n) < Fmin is true. If it is true, proceed to step 27; otherwise, proceed to step 24. Step 24: The central controller determines whether Feco≤Fr(n)≤Fmax is true. If it is true, proceed to step 28; otherwise, proceed to step 25. Step 25, Fr(n) = Feco, proceed to step 29; Step 26, Fr(n) = Fmax, proceed to step 29; Step 27, Fr(n) = Fmin, proceed to step 29; Step 28, Ft(n) = Fr(n), proceed to step 29; Step 29: Continue running to step 4.

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