Control system and control method of low-noise air source heat pump

Abstract

The invention relates to the technical field of vibration and noise reduction of air source heat pumps, and discloses a low-noise air source heat pump control system and a control method thereof.The control method comprises the following steps that the target water outlet temperature T1 and the actual water outlet temperature T2 of a heat pump system are obtained; and based on the temperature difference between the target water outlet temperature T1 and the actual water outlet temperature T2, the system operation stage is judged. The running frequency of the compressor and the passing frequency of the fan blades are monitored in real time, and prospective comparison and dynamic adjustment are carried out, so that the system can actively avoid potential beat frequency noise before the potential beat frequency noise is actually generated, the traditional passive mode of first pollution and then treatment is changed, the upgrade from feedback to feedforward is realized, and the control efficiency of the system is improved. And especially for transient processes such as compressor starting and stopping and defrosting, the initial impact noise can be remarkably inhibited, and the user experience is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of air source heat pump vibration and noise reduction technology, in particular to a control system and control method of a low-noise air source heat pump. BACKGROUND

[0002] When the air energy heat pump is running, the compressor, the fan and the fluid pipeline are the main vibration and noise sources. Vibration is transmitted through the structure path, inducing shell radiation noise; airflow noise is transmitted through the air path. The two are coupled and superimposed to form a complex sound and vibration field.

[0003] There are three major bottlenecks in the prior art: the limitations of passive measures, the singleness and hysteresis of active control, and the lack of system-level coordination. Because the stiffness and damping coefficient of passive vibration isolation elements such as rubber pads and shock absorbers are fixed, they only have optimal effects near the design operating point. When the unit is running in variable operating conditions, such as wide frequency domain operation of variable frequency compressors and severe transient processes of defrosting conditions, the passive measures will decrease in effectiveness or even fail, and may even amplify vibration due to improper frequency matching. Existing active control schemes are mostly based on single type sensors such as accelerometers for feedback control, which belong to hysteresis control after the occurrence. For known and predictable strong disturbance processes such as compressor start-up and defrosting, there is a lack of feedforward predictive control capability, and the response speed and control accuracy are insufficient. Although vibration and noise are of the same origin, their transmission paths and characteristics are different. Existing schemes often deal with structural vibration or air sound in isolation, and fail to observe and control the unit's operating state as a whole system, lacking a coordinated optimization strategy for multiple actuators, which may lead to new problems such as energy consumption for noise reduction or vibration suppression leading to noise frequency shift. SUMMARY

[0004] In view of the deficiencies of the existing air source heat pump in use as described in the background, the present application provides a control system and control method of a low-noise air source heat pump, which has the advantages of noise predictability avoidance, sound and vibration adaptive collaborative control, and solves the technical problems raised in the above background.

[0005] The present application provides the following technical solution: a control method of a low-noise air source heat pump, comprising the following steps: Obtaining the target water outlet temperature T1 and the actual water outlet temperature T2 of the heat pump system; Based on the temperature difference between the target water outlet temperature T1 and the actual water outlet temperature T2, determining the system operating stage; When it is determined that the system is in the first operating stage, a first noise collaborative control process is performed; wherein the first noise collaborative control process comprises: based on the current operating frequency F1 of the compressor and the current operating frequency F2 of the fan, beat frequency prediction and adjustment are performed, and the compressor near-field sound signal and the fan near-field sound signal are respectively collected, analyzed and abnormally controlled; When the system is in the second running phase, a second noise coordination control process is executed; wherein, the second noise coordination control process comprises: beat frequency pre-judgment and adjustment based on the current compressor running frequency F3 and the current fan running frequency F4, and acquisition, analysis and abnormal regulation of the compressor near-field sound signal and the fan near-field sound signal respectively; Wherein, the abnormal regulation strategies corresponding to the first running phase and the second running phase are different.

[0006] Preferably, the step of "beat frequency pre-judgment and adjustment based on the current compressor running frequency F1 and the current fan running frequency F2" specifically comprises: obtaining the current compressor running frequency F1; obtaining the current speed of the fan, and calculating the current fan running frequency F2 based on the speed; judging whether the absolute value of the difference between the current compressor running frequency F1 and the current fan running frequency F2 is less than or equal to a preset beat frequency threshold; if yes, adjusting the speed of the fan, and returning to execute the step of "obtaining the current speed of the fan" until the absolute value of the difference is greater than the preset beat frequency threshold.

[0007] Preferably, the step of "acquisition, analysis and abnormal regulation of the compressor near-field sound signal" specifically comprises: acquiring a first acoustic signal of the compressor near-field; calculating the total sound pressure level value N1 of the first acoustic signal, and performing frequency spectrum analysis on the first acoustic signal to obtain the single-frequency peak sound pressure level value N2 within a certain frequency band; judging whether the difference between the total sound pressure level value N1 and the single-frequency peak sound pressure level value N2 is less than a preset abnormal threshold; if yes, determining that the compressor has abnormal noise, and adjusting the running frequency of the compressor in the corresponding direction according to the current system running phase.

[0008] Preferably, the "adjusting the running frequency of the compressor in the corresponding direction according to the current system running phase" specifically comprises: when the system is in the first running phase, controlling the compressor to run at a first preset value; when the system is in the second running phase, controlling the compressor to run at a first preset value.

[0009] Preferably, the step of "acquisition, analysis and abnormal regulation of the fan near-field sound signal" specifically comprises: acquiring a second acoustic signal of the fan near-field; calculating the total sound pressure level value N3 of the second acoustic signal, and performing frequency spectrum analysis on the second acoustic signal to obtain the single-frequency peak sound pressure level value N4 within a certain frequency band; judging whether the difference between the total sound pressure level value N3 and the single-frequency peak sound pressure level value N4 is less than a preset abnormal threshold; if yes, determining that the fan has abnormal noise, and adjusting the speed of the fan in the corresponding direction according to the current system running phase.

[0010] Preferably, the "adjusting the rotating speed of the fan in a corresponding direction according to the current system running phase" specifically refers to: when the system is in the first running phase, controlling the fan to run at a second preset value of speed up; when the system is in the second running phase, controlling the fan to run at the second preset value of speed down.

[0011] Preferably, the "judging the system running phase based on the temperature difference between the target outlet water temperature T1 and the actual outlet water temperature T2" specifically refers to: calculating the temperature difference T1-T2; if the temperature difference is greater than a preset temperature difference threshold, determining that the system is in the first running phase; if the temperature difference is less than or equal to the preset temperature difference threshold, determining that the system is in the second running phase.

[0012] A control system of a low-noise air source heat pump, comprising a signal acquisition module, a signal processing module, a main control module and an execution module; the signal acquisition module is used to acquire the target outlet water temperature T1, the actual outlet water temperature T2, the compressor near-field sound signal, the fan near-field sound signal, the current operating frequency of the compressor and the current rotating speed of the fan; the signal processing module is connected to the signal acquisition module and is used to pre-process the signals acquired by the signal acquisition module; the main control module is connected to the signal processing module and is used to execute the logical steps of the control method according to any one of claims 1 to 7 and generate a control instruction; the execution module is connected to the main control module and is used to adjust the operating frequency of the compressor or the rotating speed of the fan according to the control instruction.

[0013] The present application has the following advantages: 1. The present application can actively avoid potential beat frequency noise before it actually occurs by real-time monitoring of the operating frequency of the compressor and the passing frequency of the fan blades and performing prospective comparison and dynamic adjustment. This changes the traditional passive mode of "pollution after treatment" and realizes the upgrade from feedback to feedforward. Especially for the transient process of compressor start-stop and defrosting, the initial impact noise can be significantly suppressed to improve user experience.

[0014] 2. The present application can adaptively match the abnormal noise control strategy with the system main control target by combining voiceprint analysis with intelligent control of the system running phase. When full heating is needed, the frequency is increased to avoid resonance, and when constant temperature is needed, the frequency is reduced. Thus, the heating performance and energy efficiency are guaranteed, and the contradiction between noise reduction and system core function is avoided.

[0015] 3、The present application can make the compressor and the fan as a unified sound source be observed and controlled as a whole by constructing a collaborative control platform integrating acoustic sensing, running state sensing and cloud data synchronization. Not only can it handle independent abnormalities, but also can coordinate and adjust to prevent secondary problems, while all running data form a closed loop optimization, so that the control threshold and strategy have the ability of continuous self-learning and evolution, realizing real system-level intelligent noise reduction. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The first control logic diagram of the present application; Figure 2 The second control logic diagram of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0018] A control method of a low-noise air source heat pump, please refer to the flow Figure 1 : S1: After recognizing the heating mode after starting, read the target outlet water temperature T1 and the actual outlet water temperature T2. S2: Determine: T1-T2>5℃. If yes, it is determined that the system heating is not up to temperature and is in the frequency increasing heating stage, the controller reads the current compressor running frequency F1. The controller reads the current fan speed and calculates the BPF frequency F2.

[0019] S3: Determine the beat frequency sound, F1-F2>3Hz. If yes, it is determined that there is no beat frequency sound. The current unit running data is uploaded to the server. If not, it is determined that there may be beat frequency sound. The fan speed is increased by 60rpm / min. After adjusting the speed, the controller reads the current fan speed until it is determined that there is no beat frequency sound.

[0020] S4: Compressor near-field microphone acquisition, time: 20s, output noise RMS total value N1. And Fourier transform is performed on the time domain signal, output 1 / 3 octave, and output 1KHz within single frequency peak N2.

[0021] S5: Determine if there is abnormal noise in the compressor. N1-N2<6dB. If yes, determine that there is abnormal noise in the compressor, and the compressor immediately operates to increase the frequency by 1 Hz. After the frequency increasing operation, maintain for 2 minutes. Return to S4 until S5 determines that there is no abnormal noise in the compressor, and the unit operation data is uploaded to the server. The compressor maintains the predetermined frequency increasing speed unchanged.

[0022] S6: Collect 20 seconds of data from the fan near-field microphone, output the total RMS noise value N3, and perform Fourier transform to output 1 / 3 octave. Output the single frequency peak value N4 within 1 KHz.

[0023] S7: Determine if there is abnormal noise in the fan. N3-N4<6dB. If no, determine that there is no abnormal noise in the fan, and the fan maintains the predetermined speed unchanged. The current unit operation data is uploaded to the server. If yes, determine that there is abnormal noise in the fan, and the fan immediately increases the speed by 60 rpm / min. Regardless of whether the fan speed changes, return to S1 for cyclic monitoring and dynamic adjustment.

[0024] Please refer to the flowchart Figure 2 : S1: After recognizing the heating mode after starting, read the target outlet water temperature T1 and the actual outlet water temperature T2. S2: Determine if T1-T2>5℃. If no, determine that the system is close to or has reached the heating temperature, and needs to be maintained or reduced in frequency to maintain stability. The controller reads the current compressor operating frequency F3, and reads the current fan speed, and calculates the BPF frequency F4.

[0025] S8: Determine if there is beat frequency sound. F3-F4>3Hz. If yes, determine that there is no beat frequency sound. The current unit operation data is uploaded to the server. If no, determine that there may be beat frequency sound. Increase the fan speed by 60 rpm / min. After adjusting the speed, return to read the current fan speed by the controller until it is determined that there is no beat frequency sound.

[0026] S9: Collect data from the compressor near-field microphone. Time: 20s, output the noise RMS total value N5. Perform Fourier transform on the time domain signal to output 1 / 3 octave, and output the single frequency peak value N6 within 1 KHz.

[0027] S10: Determine if there is abnormal noise in the compressor. N5-N6<6dB. If yes, determine that there is abnormal noise in the compressor, and the compressor immediately operates to decrease the frequency by 1 Hz. After the frequency decreasing operation, maintain for 2 minutes. Return to S4 until S5 determines that there is no abnormal noise in the compressor, and the unit operation data is uploaded to the server. The compressor maintains the predetermined frequency decreasing speed unchanged.

[0028] S11: Fan near-field microphone data collection for 20 seconds, output RMS noise total value N7, and Fourier transform output 1 / 3 octave. Output single frequency peak value N8 within 1KHz.

[0029] S12: Determine abnormal noise of the fan, N7-N8<6dB. If not, it is determined that the fan has no abnormal noise, and the fan maintains the system speed unchanged, and the current unit operation data is uploaded to the server synchronously; if yes, it is determined that the fan has abnormal noise, and the fan immediately reduces the speed by 60rpm / min. Whether the fan speed changes or not, it returns to S1 for cyclic monitoring and dynamic adjustment.

[0030] The use method (working principle) of the application is as follows: When the user starts the air source heat pump and sets the heating mode and target water temperature such as 45℃, the whole system starts to work. First, the main control module obtains two key parameters of target outlet water temperature T1 and real-time monitored actual outlet water temperature T2 from the unit controller through the system bus, and calculates the temperature difference ΔT=T1-T2. At the same time, the microphones arranged in the compressor near-field and the fan near-field start to be on standby for collecting acoustic signals; the main control module also continuously obtains the real-time running frequency of the compressor and the real-time speed of the fan from the bus.

[0031] The main control module compares the calculated temperature difference ΔT with the preset threshold value such as 5℃, intelligently judges the current running stage of the system, and automatically selects the corresponding optimization control path.

[0032] If ΔT>5℃: it is determined that the system is in the "heating frequency increasing stage", that is, the first running stage, the water temperature is still far from the target, and the compressor and the fan need to run at a high power to quickly heat. The system immediately enters the "active frequency increasing and noise reducing" control cycle corresponding to flow Figure 1 .

[0033] If ΔT≤5℃: it is determined that the system is in the "tending to stable or frequency reducing stage", that is, the second running stage, the water temperature has approached or reached the set value, and the system needs to run stably or reduce the power to maintain the temperature. The system immediately enters the "active frequency reducing, stable maintaining and noise reducing" control cycle corresponding to flow Figure 2 .

[0034] Path A: control flow of heating frequency increasing stage: In the beat frequency tone prospective suppression stage, the primary task of the system is to prevent the low-frequency beat frequency tone generated by the coupling of the compressor electromagnetic frequency F1 and the fan blade passing frequency F2. The main control module reads the current compressor frequency F1 and fan speed, calculates F2 in real time, and judges whether |F1-F2|≤3Hz. If so, it is predicted that the beat frequency noise sensitive to human ears may be generated, and the system will immediately send instructions to the fan speed drive to increase the fan speed by 60 rpm and recalculate the judgment until the frequency difference is greater than 3 Hz, thereby eliminating the hidden danger before the noise is generated.

[0035] After beat frequency pre-control, the compressor abnormal noise adaptive suppression is carried out, and the system starts the compressor near-field microphone to collect 20-second sound signals. The signal processing module processes the signals, calculates the total sound pressure level value N1, and obtains the single-frequency peak sound pressure level N2 in the 1 kHz frequency band through Fourier transform. The main control module calculates the difference N1-N2. If the difference is less than 6dB, it indicates that the noise energy is highly concentrated in a single frequency, which may be caused by mechanical resonance, and it is determined as abnormal noise. The system will immediately instruct the compressor variable frequency drive to actively increase the frequency by 1 Hz based on the current frequency for 2 minutes to escape the resonance point. After 2 minutes, the system returns to re-collect and analyze until the abnormality disappears N1-N2≥6dB. If there is no abnormality, the compressor runs according to the original frequency increase curve.

[0036] After completing the compressor side control, the system starts the fan near-field microphone, also collects and analyzes 20 seconds, and obtains the total sound pressure level N3 and the single-frequency peak N4. The same logic is used to determine that N3-N4<6dB is abnormal. If the fan is detected to have an abnormal single tone such as whistling, the fan speed drive is instructed to immediately increase the fan speed by 60 rpm to change its aerodynamic acoustic characteristics and eliminate the abnormal sound.

[0037] After completing a complete beat frequency pre-determination-compressor noise reduction-fan noise reduction cycle, whether the fan speed is adjusted or not, the system will return to the step "obtain target and actual water temperature" and re-determine the running stage. This means that the system will periodically and dynamically execute the above-mentioned cooperative noise reduction process during the entire heating and temperature rising process, and respond to the working condition changes in real time.

[0038] Path B: Control flow in the stable or frequency reduction stage: The control logic framework of this path is the same as path A, but the core difference is that the direction of abnormal noise control strategy is opposite to adapt to the system's "stable" operation requirements.

[0039] The logic of beat frequency tone prospective suppression is exactly the same as path A, which avoids beat frequency by fine-tuning the fan speed.

[0040] When the compressor is determined to have an abnormal single tone N5-N6<6dB by analyzing the sound signal, the control instruction of the system is to control the compressor to run at a reduced frequency of 1Hz for 2 minutes. Because in this stage, the system has a tendency to reduce the frequency, this operation can not only avoid the resonance point, but also comply with the system operation logic, avoiding unnecessary power increase.

[0041] Similarly, after determining that the fan is abnormal N7-N8<6dB, the instruction is to control the fan to reduce the speed by 60rpm.

[0042] Dynamic cycle monitoring, also returns to the initial judgment point, forming a closed loop.

[0043] During the entire use process, all the running state data, acoustic analysis results and control instructions will be uploaded to the cloud server by the main control module, and through the cloud big data analysis, the preset threshold and control amount are continuously optimized, so that the system has the ability of self-learning and performance evolution.

[0044] It should be noted that in this text, relational terms such as first and second are used only to distinguish one entity or action from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or actions. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0045] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A control method of a low-noise air source heat pump, characterized by, The method comprises the following steps: obtaining a target outlet water temperature T1 and an actual outlet water temperature T2 of a heat pump system; judging a system running stage based on a temperature difference between the target outlet water temperature T1 and the actual outlet water temperature T2; when it is determined that the system is in a first running stage, performing a first noise coordination control process; wherein the first noise coordination control process comprises: performing beat frequency pre-judgment and adjustment based on a current running frequency F1 of a compressor and a current running frequency F2 of a fan, and respectively collecting, analyzing, and abnormally regulating a compressor near-field sound signal and a fan near-field sound signal; when it is determined that the system is in a second running stage, performing a second noise coordination control process; wherein the second noise coordination control process comprises: performing beat frequency pre-judgment and adjustment based on a current running frequency F3 of a compressor and a current running frequency F4 of a fan, and respectively collecting, analyzing, and abnormally regulating a compressor near-field sound signal and a fan near-field sound signal; wherein abnormal regulation strategies corresponding to the first running stage and the second running stage are different.

2. The control method of a low-noise air source heat pump according to claim 1, characterized by: The step of "performing beat frequency pre-judgment and adjustment based on a current running frequency F1 of a compressor and a current running frequency F2 of a fan" specifically comprises: obtaining the current running frequency F1 of the compressor; obtaining a current rotating speed of the fan and calculating the current running frequency F2 of the fan based on the rotating speed; judging whether an absolute value of a difference between the current running frequency F1 of the compressor and the current running frequency F2 of the fan is less than or equal to a preset beat frequency threshold value; if yes, adjusting the rotating speed of the fan and returning to perform the step of "obtaining a current rotating speed of the fan" until the absolute value of the difference is greater than the preset beat frequency threshold value.

3. The control method of a low-noise air source heat pump according to claim 1, characterized by: The step of "respectively collecting, analyzing, and abnormally regulating a compressor near-field sound signal and a fan near-field sound signal" specifically comprises: collecting a first acoustic signal of a compressor near-field; calculating a total sound pressure level value N1 of the first acoustic signal and performing frequency spectrum analysis on the first acoustic signal to obtain a single-frequency peak sound pressure level value N2 thereof within a certain frequency band; judging whether a difference between the total sound pressure level value N1 and the single-frequency peak sound pressure level value N2 is less than a preset abnormal threshold value; if yes, determining that the compressor has abnormal noise and adjusting a running frequency of the compressor in a corresponding direction according to a current system running stage.

4. The method of claim 1, wherein: The "adjusting a running frequency of the compressor in a corresponding direction according to a current system running stage" specifically comprises: when the system is in the first running stage, controlling the compressor to run at a frequency increased by a first preset value; and when the system is in the second running stage, controlling the compressor to run at a frequency decreased by the first preset value.

5. The method of claim 1, wherein: The step of collecting, analyzing and abnormally regulating the near-field sound signal of the fan specifically comprises: collecting a second acoustic signal of the near field of the fan; calculating a total sound pressure level value N3 of the second acoustic signal, and performing frequency spectrum analysis on the second acoustic signal to obtain a single-frequency peak sound pressure level value N4 of the second acoustic signal within a certain frequency band; determining whether the difference between the total sound pressure level value N3 and the single-frequency peak sound pressure level value N4 is less than a preset abnormal threshold value; if yes, it is determined that the fan has abnormal noise, and the speed of the fan is adjusted in a corresponding direction according to the current system operation stage.

6. The method of claim 1, wherein: The step of adjusting the speed of the fan in a corresponding direction according to the current system operation stage specifically comprises: when the system is in the first operation stage, controlling the fan to run at a second preset value; when the system is in the second operation stage, controlling the fan to run at the second preset value.

7. The method of claim 1, wherein: The step of determining the system operation stage based on the temperature difference between the target outlet water temperature T1 and the actual outlet water temperature T2 specifically comprises: calculating the temperature difference T1-T2; if the temperature difference is greater than a preset temperature difference threshold value, it is determined that the system is in the first operation stage; if the temperature difference is less than or equal to the preset temperature difference threshold value, it is determined that the system is in the second operation stage.

8. A control system of a low-noise air source heat pump for implementing the control method of a low-noise air source heat pump according to any one of claims 1 to 7, characterized in that: The system comprises a signal acquisition module, a signal processing module, a main control module and an execution module; the signal acquisition module is used to acquire the target outlet water temperature T1, the actual outlet water temperature T2, the near-field sound signal of the compressor, the near-field sound signal of the fan, the current operating frequency of the compressor and the current speed of the fan; the signal processing module is connected to the signal acquisition module and is used to pre-process the signals acquired by the signal acquisition module; the main control module is connected to the signal processing module and is used to execute logical steps and generate control instructions; the execution module is connected to the main control module and is used to adjust the operating frequency of the compressor or the speed of the fan according to the control instructions.

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