Inverter compressor resonance avoidance control method based on acoustic sensing

Abstract

The invention provides a frequency conversion compressor resonance avoidance control method based on acoustic sensing. The method comprises the steps that an acoustic sensor of a compressor cavity is used for collecting operation acoustic signals; applying + / -1Hz small disturbance above and below the current compressor operation frequency to calculate a disturbance frequency spectrum, and generating a frequency modulation direction suggestion in combination with the current compressor operation frequency, a generated energy variation and a resonance sensitivity index; determining an initial frequency modulation amplitude based on the resonance sensitivity index, and generating a frequency modulation suggested amplitude, a frequency modulation target frequency and a linkage control mark; and executing the frequency modulation target frequency, monitoring a resonance sensitivity index in real time, and if new resonance is detected, triggering reverse fine tuning to generate a new frequency modulation amplitude. According to the method, disturbance-driven frequency spectrum identification is used for replacing a traditional amplitude sudden increase method, strategy compression and real-time feedback are used for replacing a fixed frequency modulation rule, and a control system has higher identification precision, a better anti-vibration strategy and higher robustness under complex working conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of acoustic sensing, and particularly relates to a variable frequency compressor resonance avoidance control method based on acoustic sensing. BACKGROUND

[0002] Variable frequency compressors are widely used in heat pump, air conditioning and refrigeration scenes, which realize efficient operation and load matching by adjusting the motor operating frequency. However, at certain frequencies and their multiple frequency points, the internal structure of the compressor is prone to excite resonance phenomenon, causing problems such as increased noise, severe vibration and even mechanical fatigue. The traditional control strategy generally adopts a static method of preset resonance frequency avoidance, that is, the controller skips a specific frequency band to avoid resonance risk. However, due to the dynamic drift of actual resonance points affected by factors such as equipment aging, load changes and refrigerant state, the static rule is easy to fail in long-term operation. At the same time, some existing technologies use acoustic sensors combined with FFT to extract frequency spectrum energy for resonance identification, but mainly rely on threshold judgment of amplitude mutation, which is easily disturbed by background noise fluctuations and other disturbance sources, leading to misjudgment, missed judgment or false triggering of frequency modulation, and cannot judge whether it is in a resonance critical state, nor can it deduce the frequency modulation direction based on disturbance response. Even if the resonance state is identified, the controller often uses a fixed proportion or one-way frequency modulation strategy, which lacks frequency modulation rate adjustment and working condition feedback mechanism, and is difficult to cope with changes in multiple device models, complex installation structures and dynamic use scenarios. The frequency modulation action may deviate from the optimal working zone or repeatedly jump frequency, affecting the stability, comfort and energy efficiency of the system. SUMMARY

[0003] The purpose of the present application is to propose a variable frequency compressor resonance avoidance control method based on acoustic sensing, which adopts a phased execution and dynamic feedback mechanism to build a complete closed-loop control logic.

[0004] In order to achieve the above purpose, the present application provides a variable frequency compressor resonance avoidance control method based on acoustic sensing, which comprises: S1: Acquire running acoustic signals through acoustic sensors in the compressor cavity, generate frequency spectrum vectors through framing and Fourier transform, extract 2 times frequency and 3 times frequency characteristic frequency bands of the current frequency spectrum vector, and synchronously acquire the current compressor operating frequency; S2: Apply ±1Hz small amplitude disturbance to the 2 times frequency and 3 times frequency characteristic frequency bands of the current frequency spectrum vector above and below the current compressor operating frequency to calculate the disturbance frequency spectrum, generate energy change amount in combination with the current compressor operating frequency, then the controller statistically analyzes the high frequency band sound spectrum fluctuation degree of the current frame of the system to generate an anti-interference term, obtains a resonance sensitivity index in combination with the energy change amount, and generates a frequency modulation direction suggestion; wherein the frequency modulation direction includes frequency increase and frequency decrease; S3: Determine an initial frequency modulation amplitude based on the resonance sensitivity index, suppress the amplitude based on the deviation between the current compressor operating frequency and the rated frequency, and generate a frequency modulation recommended amplitude, a frequency modulation target frequency, and a linkage control flag; S4: executing the frequency modulation target frequency in stages according to the minimum step size, and monitoring the resonance sensitivity index in real time. If a new resonance is detected, reverse fine-tuning is triggered to generate a new frequency modulation amplitude; Among them, when the linkage control flag = 1, the frequency modulation action is performed according to the frequency modulation recommended amplitude, and the fan PWM signal and the expansion valve step opening are adjusted according to the direction and size of the frequency modulation recommended amplitude. After the frequency modulation execution is completed, the updated operating frequency is generated and the execution result is marked as a status: If the updated operating frequency reaches the frequency modulation target frequency and the resonance sensitivity index is lower than the preset threshold value in two consecutive cycles, it is considered that the frequency modulation vibration avoidance is successful and the frequency modulation status flag is set to 1.

[0005] Furthermore, the acoustic sensor is a capacitive electret microphone module, which is a standard model with a frequency response range of 20Hz to 10kHz and a sensitivity of approximately -42dB; the capacitive electret microphone module is connected to the ADC channel of the main controller via an analog front end, and the ADC sampling rate is fixedly set to 8000Hz.

[0006] Furthermore, the S1 specifically includes: Collect the original acoustic data, recorded as ; During each frame processing, the controller first multiplies the current frame data by a standard Hamming window function to reduce the impact of discontinuities at the edge of the window function on spectrum analysis; After windowing is completed, the controller performs a fast Fourier transform operation on the frame data to convert the time domain signal into a frequency domain representation; The spectrum vector obtained after conversion is , indicating that in the current frame At time , the acoustic energy amplitude of each frequency component inside the compressor cavity; For the spectrum vector Perform maximum value normalization to ensure that the system can still compare the energy distribution between different frequency bands under different hardware configurations; Synchronously obtain the current compressor operating frequency , based on the current compressor operating frequency In the spectrum vector Two key frequency bands are located in the middle: the first frequency band is centered at 2 times the current compressor operating frequency, and extends 5Hz upward and downward; the second frequency band is centered at 3 times the frequency, and also extends within the range of ±5Hz; the first and second frequency bands are combined to form the variable , used to represent the characteristic frequency region in the sound spectrum most relevant to the frequency multiplication resonance.

[0007] Further, the S2 specifically includes: On the basis of the current compressor operating frequency , two perturbation frequency points are generated: the upper perturbation and the lower perturbation ; during the perturbation process, new sound spectrum data is collected in real time to generate perturbation spectrum vectors, including the upper perturbation spectrum vector and the lower perturbation spectrum vector ; Within the ±5Hz range centered on and , two key frequency multiplication feature segments are extracted, denoted as and , which are combined into the total frequency band , and within the total frequency band , the energy difference between the perturbation spectrum vectors and the average energy of the current compressor operating frequency is compared to construct the energy change amount after positive and negative perturbations; The mean square fluctuation amount in the 0-500Hz frequency spectrum high frequency band is counted to construct an anti-interference term; According to the anti-interference term and the energy change amount, a resonance sensitivity index is calculated, which is used to measure the asymmetric amplitude of the perturbation response, and the larger the value, the more sensitive the current frequency is to the perturbation, and the closer it is to the resonance critical region.

[0008] Further, the frequency modulation direction suggestion is generated as follows: An empirical threshold is set; When the resonance sensitivity index is greater than the empirical threshold , it is determined that the current frequency has a resonance risk, and the frequency modulation avoidance process is entered, including: The frequency modulation direction is determined by the comparison of the upper and lower perturbation response amplitudes of the energy change amount: if the upper perturbation response amplitude is less than the lower perturbation response amplitude , it indicates that the response amplitude in the frequency increasing direction is smaller, i.e., it is more likely to move away from the resonance region after frequency increasing, and the system sets the frequency modulation direction to +1; otherwise, it is set to -1.

[0009] Further, the S3 specifically includes: The resonance sensitivity index is multiplied by a preset proportionality coefficient to obtain an initial frequency modulation amplitude; The current compressor operating frequency is calculated a relative deviation between the initial frequency modulation amplitude and the current compressor operating frequency; if the relative deviation exceeds a preset tolerance threshold, the initial frequency modulation amplitude is suppressed to slow down the frequency modulation speed; a frequency modulation suggestion amplitude is generated according to the initial frequency modulation amplitude and the relative deviation, combined with the current compressor operating frequency to obtain a frequency modulation target frequency.

[0010] Further, the S3 further comprises: a linkage control flag is triggered according to the resonance sensitivity index, for indicating whether linkage control of the fan speed or the electronic expansion valve is needed, specifically: when the resonance sensitivity index is greater than a preset threshold, the system outputs the linkage control flag = 1, indicating that the expansion valve / fan needs to be adjusted simultaneously.

[0011] Further, the S4 specifically comprises: a frequency modulation suggestion amplitude is obtained, and equal-step frequency modulation is performed at a preset minimum frequency step , the direction of which is determined by the current frequency modulation direction , and the step is set by the PWM controller. After each frequency update, return to S2 to reconstruct the latest frequency spectrum and calculate a new resonance sensitivity index ; if the new resonance sensitivity index exceeds a set resonance re-determination threshold after two consecutive updates, enter reverse fine tuning.

[0012] Further, the reverse fine tuning specifically comprises: based on the new resonance sensitivity index , a reverse fine tuning amount is obtained by reversely applying a proportionally scaled fine tuning amount in the current frequency modulation direction , for exiting the new resonance boundary; wherein the reverse fine tuning is triggered immediately when an abnormal resonance response is detected, and the new frequency is written into the controller register and returns to S1.

[0013] Further, the controller continuously collects and processes the original acoustic signal at a sampling rate of 8000 Hz, and the original acoustic signal is processed by sliding window framing with 128 milliseconds as one frame, each frame containing 1024 sampling points, the frame overlap being 768 points, i.e. the frame shift being 256 points, corresponding to a time interval of 32 milliseconds, ensuring continuous coverage of the spectral information on the time axis.

[0014] The present application has at least the following beneficial technical effects: The application provides a variable frequency compressor resonance avoidance control method based on acoustic sensing and disturbance response identification, which adopts a phased execution and dynamic feedback mechanism to construct a complete closed-loop control logic. First, an acoustic sensor installed in the compressor cavity collects running acoustic wave data and extracts frequency spectrum features, while synchronously reading the current compressor frequency, to construct a feature frequency band related to 2 times frequency and 3 times frequency in real time. Subsequently, the system applies a small disturbance above and below the current frequency, collects acoustic spectrum change data before and after the disturbance, constructs a disturbance response asymmetry index, which is used to determine whether the current is in the resonance critical zone, and outputs a clear frequency modulation direction. The disturbance intensity and direction linkage mechanism is introduced when generating the frequency modulation strategy, and the relative deviation between the current frequency and the rated frequency is combined to compress the frequency modulation amplitude, preventing frequency jump into the non-design working area. In the frequency modulation execution stage, a step frequency modulation method based on the main loop cycle is adopted, and the real-time resonance sensitivity index is continuously calculated during the frequency modulation process. If resonance is identified again, a fine tuning action is triggered to quickly exit the risk frequency band, realizing a "identification-adjustment-verification-correction" closed-loop process. The method replaces the traditional amplitude surge method with disturbance-driven spectrum identification, and replaces the fixed frequency modulation rule with strategy compression and real-time feedback, so that the control system has higher identification accuracy, better resonance avoidance strategy and stronger robustness under complex working conditions, and is suitable for variable frequency compressors of multiple types and structures. BRIEF DESCRIPTION OF DRAWINGS

[0015] The application is further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled in the art, other drawings can be obtained without creative labor according to the following drawings.

[0016] Figure 1 The application provides a variable frequency compressor resonance avoidance control method based on acoustic sensing. DETAILED DESCRIPTION

[0017] The embodiments of the application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the application, and cannot be understood as a limitation on the application.

[0018] As shown in Figure 1 The application provides a variable frequency compressor resonance avoidance control method based on acoustic sensing, which comprises the following steps S1-S4: S1: Collecting running acoustic signals by an acoustic sensor of the compressor cavity, generating a frequency spectrum vector through framing and Fourier transform, extracting 2 times frequency and 3 times frequency feature bands of the current frequency spectrum vector, and synchronously acquiring the current compressor operating frequency.

[0019] Specifically, the goal of this step is to extract high-quality acoustic spectrum data from a running variable-frequency compressor, which can be used to determine resonance. This spectrum data must not only accurately reflect the current acoustic state of the compressor cavity but also be able to extract frequency amplitude changes related to the second and third harmonics of the compressor's current operating frequency.

[0020] Furthermore, acoustic signals are collected using a standard condenser electret microphone module mounted outside the compressor cavity (e.g., the Knowles EK-23132-P07). It has a frequency response range of 20Hz to 10kHz and a sensitivity of approximately -42dB. This microphone is connected to the main controller's ADC channel via an analog front end (including a preamplifier and anti-aliasing filter). The ADC sampling rate is fixed at 8000Hz to ensure accurate sampling in the low-frequency range of 0–500Hz. To eliminate the additional effects of housing resonance and mechanical noise, the microphone is mounted on the side of the compressor housing using a magnetic mount, away from the air outlet and mechanical connections.

[0021] The collected time series signal is recorded as This signal is raw acoustic data collected by a condenser microphone mounted on the surface of the compressor cavity during operation. The controller continuously collects and processes this data at an 8000Hz sampling rate. To facilitate subsequent spectral analysis, the controller divides this one-dimensional time series signal into 128-millisecond frames using a sliding window. Each frame contains 1024 sampling points, with an inter-frame overlap of 768 points, resulting in a frame shift of 256 points and a corresponding time interval of 32 milliseconds, ensuring continuous coverage of the spectral information along the time axis.

[0022] During each frame processing, the controller first multiplies the current frame data by a standard Hamming window function to reduce the impact of discontinuities at the edge of the window function on spectrum analysis. After the windowing is completed, the controller performs a fast Fourier transform (FFT) operation on the frame data to convert the time domain signal into a frequency domain representation. The spectrum vector obtained after the conversion is , indicating that in the current frame At this moment, the acoustic energy amplitude of each frequency component inside the compressor cavity. Since the resonance characteristics of this patent are concentrated in the low frequency band, especially the 2nd and 3rd frequency ranges of the operating frequency, only the spectrum data in the range of 0 to 500 Hz is retained, and the remaining high-frequency parts are not processed.

[0023] To avoid the influence of different installation environments, gain settings or microphone sensitivity on the spectrum amplitude, The vector is uniformly maximum normalized. The normalization ensures that the system can compare the energy distribution among different frequency bands under different hardware configurations. According to the system configuration parameters, the combination of 1024-point FFT and 8000Hz sampling rate is adopted, at this time the frequency resolution is about 7.8Hz, so in the range of 0 to 500Hz, a vector composed of 64 discrete frequency points can be obtained. For example, the point with frequency index 6 corresponds to about 47Hz, index 12 corresponds to 93Hz, and index 18 corresponds to 140Hz, which constitutes the most critical feature frequency point in the resonance judgment process.

[0024] In order to support the subsequent identification of the compressor frequency resonance characteristics, this step needs to synchronously obtain the current compressor operating frequency while extracting the sound spectrum . This parameter is obtained by communicating with the compressor variable frequency drive module through the interface in the controller mainboard, and the specific method is to read the frequency setting register value corresponding to the PWM control signal. The data reading period is set to 100 milliseconds, which ensures sufficient time resolution and response synchronization during system operation. Among them, the collected is a floating-point scalar with Hz as the unit, representing the actual operating frequency of the compressor at the current time. This value usually dynamically changes between 20Hz and 100Hz, and changes with load demand and temperature control algorithm adjustment.

[0025] According to the physical principle of resonance identification, the structural resonance of the compressor tends to occur at integer multiples of its operating frequency, especially at 2 times and 3 times. Therefore, in order to provide more accurate and targeted frequency spectrum input for the subsequent steps, this step immediately locates two key frequency bands in the frequency spectrum vector based on the value . The first frequency band is centered on 2 times the current frequency, and is extended by 5Hz up and down; the second frequency band is centered on 3 times the frequency, and is also extended by ±5Hz. These two frequency bands together form the variable , which represents the feature frequency region in the sound spectrum most relevant to the frequency resonance.

[0026] In terms of implementation, the controller extracts all amplitude data points in corresponding to the above two frequency intervals, forms the variable , and provides it for the next step for resonance judgment or disturbance response analysis. For example, if the value of is 48Hz at a certain time, then 2 times is 96Hz and 3 times is 144Hz, the system will extract all frequency point amplitudes between 91Hz and 101Hz and 139Hz and 149Hz from to form the corresponding This method avoids the inefficiency of blind search for resonance signs throughout the entire spectrum, and can accurately focus on the area where resonance may occur, thus improving the real-time performance of the algorithm and being closer to the mechanism of compressor physical structure resonance.

[0027] The two variables output by this step will be directly used as inputs for the next step of disturbance analysis: : Complete 0-500Hz amplitude normalized frequency spectrum vector, dimension 64; : Current compressor operating frequency, provided by the frequency converter control logic, scalar value.

[0028] S2: 2 times and 3 times frequency band features of the current frequency spectrum vector, ±1Hz small perturbation is applied above and below the current compressor operating frequency to calculate the perturbed frequency spectrum, combined with the current compressor operating frequency, the energy change is generated, then the controller calculates the fluctuation degree of the high frequency band sound spectrum of the current frame of the system, generates the anti-interference term, combines the energy change to obtain the resonance sensitivity index, and generates the frequency adjustment direction suggestion; wherein the frequency adjustment direction includes frequency increase and frequency decrease.

[0029] Specifically, this step uses the frequency spectrum vector output in step one and the current compressor operating frequency together, the system performs a "structure resonance sensitivity test" based on small perturbation excitation to dynamically capture whether the current operating frequency is approaching the multiple frequency resonance region, and accordingly determine whether to start frequency avoidance control and in which direction to adjust the frequency. This method is especially suitable for cases where the compressor multiple frequency resonance frequency drifts with load, installation state, and refrigerant fluctuations, and has higher real-time performance and adaptability than traditional threshold detection.

[0030] Further, the system generates two perturbation frequency points based on the current compressor operating frequency : upper perturbation and lower perturbation . Each perturbation lasts for 200ms, which is achieved by the controller modifying the drive frequency through the frequency converter. New sound spectrum data is collected in real time during the perturbation process, denoted as and . Then, the system extracts two key multiple frequency feature segments: ±5Hz range centered on and , denoted as and , which is a key step in modeling the resonance characteristic structure in this invention, specifically matching the compressor multiple frequency resonance mechanism. The above two frequency bands are combined into the total frequency band , and in this interval, compare the average energy difference between the disturbance spectrum and the current spectrum, construct the energy change after positive and negative disturbance: ; In this formula, represents the spectrum vector after the frequency disturbance or the downward disturbance, is the original frequency spectrum, is the number of frequency points in the frequency band (usually 14 to 16, depending on the spectral resolution). This energy change measures the difference in acoustic response in the octave-related region before and after the disturbance, reflecting the system's sensitivity to frequency disturbance, which is the first layer of criteria for identifying whether it is at the resonance boundary.

[0031] However, due to the presence of a large amount of non-structural noise in the compressor system, such as sudden changes in refrigerant flow and expansion valve switching actions, these will cause non-typical spectral amplitude changes in the high frequency band, which may mislead the system. Therefore, an anti-interference term is introduced as a regular modification of the resonance recognition criterion, which is constructed by statistical mean square fluctuation in the high frequency band (200-500Hz) of 0-500Hz spectrum, specifically: ; Among them, is the average spectral amplitude in the 200-500Hz frequency band, is the number of frequency points in the frequency band, is the adjustment term weight (usually set to 0.5 to 0.8), which can be statically configured in the controller. The physical meaning of the anti-interference term is a penalty for non-structural spectral fluctuations in the disturbance background, to prevent mistaking mechanical noise or fluid disturbance as structural resonance.

[0032] After extracting the acoustic spectrum changes before and after the frequency disturbance, the system further constructs the resonance sensitivity index for judging whether it is in the critical region of structural resonance. This index is based on the difference in response amplitude of the disturbance in two directions, and an anti-interference term is introduced to exclude the interference of non-structural noise. Specifically, the system first obtains the spectral change through positive disturbance (i.e. increasing the frequency by 1Hz) and the change through negative disturbance (i.e. reducing the frequency by 1Hz), which respectively reflect the difference in response strength of the system in the 2 times frequency and 3 times frequency characteristic frequency band. Subsequently, the controller statistically analyzes the acoustic spectrum fluctuation degree of the current frame in the high frequency band (e.g. 200Hz to 500Hz), and generates an anti-interference term , which can be regarded as a quantitative estimation of non-resonant high-frequency activities within the system. Based on the three, the system calculates , which measures the asymmetric amplitude of the disturbance response. The larger the value, the more sensitive the current frequency is to the disturbance, and the closer it is to the resonance critical region. Its calculation formula is: ; Where, and represent the response amplitude changes of the forward and reverse disturbances to the frequency spectrum, respectively, and γ(t) is the anti-interference term. The larger the value, the more sensitive the current frequency is to the disturbance, and the closer it is to the resonance critical region. Through this index, the system can accurately determine whether the compressor is close to the resonance frequency band, and provide a basis for subsequent frequency modulation control.

[0033] To ensure that the judgment standard has universality and controllability, the system sets an empirical threshold , for example, the value is 0.12. When is greater than the threshold, it means that the current frequency has obvious resonance risk, and it is recommended to enter the frequency modulation avoidance process. The frequency modulation direction is determined by the comparison of the two disturbance response amplitudes: if is less than , it means that the response amplitude in the frequency increasing direction is smaller, that is, it is more likely to move away from the resonance region after frequency increasing, and the system sets the frequency modulation direction to +1; otherwise, it is set to -1. Taking an actual running case as an example, when the current frequency is 47Hz, the system detects that is 0.09, is 0.27, and the anti-interference term is 0.04. The calculation result is 0.14, which is higher than the threshold 0.12. The system confirms that it is in the resonance boundary region, and since the influence of frequency increasing is smaller, it recommends the frequency modulation direction to be frequency increasing, that is, . The resonance judgment and frequency modulation direction identification process are all completed locally by the controller, and the typical execution period does not exceed 500 milliseconds, which can be embedded in an embedded MCU or DSP system with a main frequency of 100MHz or above.

[0034] This step outputs two core variables: : resonance sensitivity index, representing the response strength of the current frequency to small disturbances; : frequency modulation direction, represents frequency increasing, represents frequency decreasing.

[0035] S3: Determine the initial frequency modulation amplitude based on the resonance sensitivity index, combine the deviation of the current compressor operating frequency and the rated frequency to suppress the amplitude, generate the frequency modulation suggestion amplitude, the frequency modulation target frequency and the linkage control flag.

[0036] Specifically, combined with the typical response characteristics of the air conditioner compressor in the running process, this step builds a dynamic amplitude calculation mechanism based on the disturbance identification result when calculating the frequency modulation amplitude. Specifically, the system first multiplies the value of the resonance sensitivity index identified in the last stage by a preset proportional coefficient to obtain an initial frequency modulation suggestion amplitude. This coefficient is usually between 4 and 6, and the system can be configured according to the device model. The initial suggestion amplitude generated jointly determines whether the current frequency should be increased or decreased . This calculation structure can quickly adjust the frequency modulation strength according to the change trend of , realize the response enhancement of high sensitive frequency points, and the micro amplitude avoidance of boundary frequency points. In order to ensure that the frequency modulation behavior does not cause the compressor to deviate from the design operating condition area, the system further reads the current compressor operating frequency and compares it with the rated frequency of the device to calculate the relative deviation. If the deviation exceeds the set threshold (such as 10%), the above frequency modulation suggestion amplitude is scaled and suppressed, only a part of the original suggestion amplitude is executed, to slow down the frequency dispersion trend. This setting is to prevent abnormal refrigerant distribution, current fluctuation or energy efficiency decline caused by frequency modulation in the high or low frequency band. The final output frequency modulation amplitude is the result after S1 and S2 calculation and suppression, for the next controller execution module to call.

[0037] Further, in order to ensure that the frequency modulation behavior is always within the physically allowed range, the system introduces a dynamic suppression mechanism when calculating the suggested frequency modulation amplitude, which is used to limit the change rate of the frequency adjustment amplitude under certain conditions. The core idea of this mechanism is: if the current compressor operating frequency is already very close to or significantly deviates from the rated frequency of the device, the frequency modulation amplitude should be reduced to avoid entering the non-design working interval, and prevent control stability problems caused by compressor efficiency decline, current load mutation or abnormal refrigerant flow rate.

[0038] In specific execution, the system first calculates the relative deviation between the current compressor operating frequency and the rated frequency , that is, the percentage of the difference between the two relative to the rated frequency. If the relative deviation exceeds the preset tolerance threshold , for example, in the range of 10% to 15%, the system will calculate the initial FM amplitude Suppress and retain only a part of it (such as 60%) to slow down the frequency modulation speed. This proportional suppression is achieved by setting an adjustment factor The factor decreases as the deviation increases, thereby automatically reducing the intensity of the frequency modulation action when the frequency approaches the boundary; if the frequency is near the rated range, the system does not scale the frequency modulation amplitude and maintains the original value.

[0039] The calculation formula of the adjustment factor is as follows: ; like Exceeding the threshold , then the adjustment factor is set to 0.6, indicating strong suppression; if Less than or equal to the threshold ,but Set to 1, indicating no suppression. The final FM amplitude of the system It can be obtained by the following formula:

[0040] in, Controls the compression of FM amplitude, The relative deviation between the current frequency and the rated frequency is calculated. is the initial FM amplitude calculated based on resonance sensitivity and other factors, is the final FM amplitude.

[0041] Finally, the system will make the initial frequency suggestion and repressive factors Multiply them together to get the final FM amplitude that will actually be executed. The frequency modulation amplitude will be different from the current compressor operating frequency. Add together to get the recommended new target frequency , which the controller uses to set the compressor's new operating frequency in subsequent steps. This mechanism ensures that the frequency adjustment recommendation reflects the avoidance intent determined in the previous step based on disturbance intensity and direction, while also automatically considering whether the current frequency is approaching physical boundaries, thereby maintaining the effectiveness of the avoidance action and the stability of equipment operation.

[0042] In order to further improve the stability of strategy execution and the overall comfort of the system, this step also introduces an optional control flag ,Depend on Trigger is used to indicate whether linkage control of fan speed or electronic expansion valve is required. ( For preset linkage control threshold, such as 0.2, the system will output , indicating that it is recommended to appropriately increase the fan speed and the opening of the expansion valve while performing the frequency modulation action to ensure that the refrigerant flow and heat exchange capacity can compensate for the change in compression work caused by frequency modulation in a timely manner.

[0043] The final output result includes two core variables: : final frequency modulation amplitude, unit Hz; : frequency modulation target frequency for subsequent controller adjustment.

[0044] Optional output variables are: : linkage control flag, indicating that the expansion valve / fan needs to be adjusted simultaneously.

[0045] S4: Perform the frequency modulation target frequency in stages with the minimum step size, and monitor the resonance sensitivity index in real time. If a new resonance is detected, trigger the reverse fine tuning and generate a new frequency modulation amplitude; Specifically, this step converts the final frequency modulation amplitude and the frequency modulation target frequency calculated in the previous stage into actual control instructions to drive the variable frequency compressor to change the operating frequency, thereby achieving resonance frequency band avoidance. In order to improve the controllability and system stability of the execution process, this step divides the frequency modulation process into two stages: initial adjustment stage and dynamic monitoring stage. In the initial stage, the controller first judges the difference between the current compressor operating frequency and the frequency modulation target frequency , and performs equal-step frequency modulation with a preset minimum frequency step size . The direction is determined by , and the step size is set by the PWM controller, which is usually 0.5Hz or 1Hz. The controller main loop period is usually 100ms, and the frequency is updated once per cycle. The execution logic is as follows: ; Among them: represents the updated operating frequency; is the preset minimum frequency step size of the controller; is a sign function that ensures that the frequency modulation direction is consistent with the recommended direction.

[0046] After each frequency update, the system immediately triggers a sound spectrum acquisition and disturbance response analysis to reconstruct the latest frequency spectrum And reuse the perturbation sensitivity mechanism of step two to get a new resonance sensitivity index If the updated value is detected to be higher than the set resonance threshold value for two consecutive times , the system considers that the current frequency modulation path may have entered a new resonance frequency band.

[0047] To deal with such situations, the controller introduces a reverse fine-tuning mechanism, which applies a scaled fine-tuning amount in the opposite direction of the current frequency modulation to exit the new resonance boundary. The reverse fine-tuning amount is defined as follows: ; Where: is the fine-tuning coefficient, usually set to 0.3 to 0.5, to control the amplitude of the fine-tuning action; is the latest perturbation response index; is the resonance determination threshold value; is still used to maintain directionality.

[0048] The reverse fine-tuning action is triggered immediately when an abnormal resonance response is detected, and the new frequency is written to the controller register to re-enter the next frequency modulation cycle. Through this mechanism, the system has the dynamic correction ability of "first modulation-then judgment-then modulation", which can greatly improve the control accuracy in the presence of identification errors, perturbation lags, and sudden changes in working conditions. The entire frequency modulation process is realized through the PWM control interface between the controller and the variable frequency drive module. Usually, the frequency control word is transmitted through CAN or UART bus, and the frequency modulation response period is controlled between 0.5 seconds and 2 seconds, depending on the device model and system inertia dynamic adjustment.

[0049] In addition to the main frequency control channel, this step also responds to the linkage control flag output in step three . When , the system adjusts the fan speed and electronic expansion valve opening simultaneously during frequency modulation to match the changes in compressor refrigerant flow and heat exchange capacity. The specific execution logic is: according to the direction and size of adjust the fan PWM signal (increase 10%~20% duty cycle) and the expansion valve step opening (increase 5~10 steps) to improve refrigerant stability and comfort control accuracy. After the frequency modulation is executed, the system needs to mark the execution result. If reaches , and is lower than for two consecutive periods, it is considered that the frequency modulation anti-vibration is successful, and the frequency modulation state flag is set; otherwise, it is determined that the frequency modulation failsIf the frequency of the current is not within the range, the controller will re-trigger the strategy module to generate a new frequency adjustment suggestion.

[0050] It should be noted that the above-described workflow is merely illustrative and does not limit the scope of protection of the present application. In actual applications, a person skilled in the art can select part or all of the above-described workflow to achieve the purpose of the embodiment according to actual needs, which is not limited herein.

[0051] In addition, technical details not described in detail in the embodiment can be referred to the parameter operation method provided by any embodiment of the present application, which will not be described here.

[0052] It should be noted that in this document, the terms "comprise", "comprise", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or other elements inherent to such a process, method, article or system. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article or system that includes the element.

[0053] The above-mentioned embodiment numbers of the present application are only for description, not representing the advantages or disadvantages of the embodiments.

[0054] From the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be realized by means of software and necessary general hardware platforms, of course, they can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a magnetic disk, an optical disk) and includes a plurality of instructions for making a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) execute the methods described in various embodiments of the present application.

[0055] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields based on the content of the present application specification and drawings, are also included in the patent protection scope of the present application.

Claims

1. A method of resonance avoidance control for a variable frequency compressor based on acoustic sensing, characterized by, The method comprises: S1: Collecting an operating acoustic signal through an acoustic sensor of a compressor cavity, generating a frequency spectrum vector through frame division and Fourier transform, extracting a 2nd and 3rd harmonic feature frequency band of a current frequency spectrum vector, and synchronously acquiring a current compressor operating frequency; S2: Applying a small perturbation of ±1 Hz above and below the current compressor operating frequency to the 2nd and 3rd harmonic feature frequency band of the current frequency spectrum vector to calculate a perturbation frequency spectrum, combining the current compressor operating frequency to generate an energy change amount, then a controller statistically analyzes a high-frequency band acoustic spectrum fluctuation degree of a current frame of the system to generate an anti-interference term, combines the energy change amount to obtain a resonance sensitivity index, and generates a frequency modulation direction suggestion; wherein the frequency modulation direction comprises frequency increase and frequency decrease; S3: Determining an initial frequency modulation amplitude based on the resonance sensitivity index, combining a deviation between the current compressor operating frequency and a rated frequency to suppress the amplitude, and generating a frequency modulation suggestion amplitude, a frequency modulation target frequency, and a linkage control flag; S4: Executing the frequency modulation target frequency in stages with a minimum step size and monitoring the resonance sensitivity index in real time, and triggering a reverse fine tuning if a new resonance is detected to generate a new frequency modulation amplitude; Wherein, when the linkage control flag = 1, a frequency modulation action is performed according to the frequency modulation suggestion amplitude, the fan PWM signal and the expansion valve step opening are adjusted according to the direction and size of the frequency modulation suggestion amplitude, and after the frequency modulation execution is completed, an updated operating frequency is generated, and the execution result is marked with a state: If the updated operating frequency reaches the frequency modulation target frequency, and the resonance sensitivity index is lower than a preset threshold value in two consecutive periods, it is considered that the frequency modulation anti-resonance is successful, and the frequency modulation state flag = 1 is set; otherwise, it is determined that the frequency modulation fails, the frequency modulation state flag = 0 is set, and the process returns to S3 to generate a new frequency modulation suggestion.

2. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The acoustic sensor is a capacitive electret microphone module, which is selected as a standard model, has a frequency response range of 20 Hz to 10 kHz, and has a sensitivity of about -42 dB; the capacitive electret microphone module is connected to an ADC channel of a main controller through an analog front end, and the ADC sampling rate is fixedly set as 8000 Hz.

3. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The S1 specifically comprises: The raw acoustic data is collected and denoted as ; In each frame processing process, the controller first multiplies the current frame data by a standard Hamming window function to reduce the influence of discontinuity at the edge of the window function on the frequency spectrum analysis; After the windowing is completed, the controller performs a fast Fourier transform operation on the frame data to convert the time domain signal into a frequency domain representation; The spectrum vector obtained after conversion is , representing the acoustic energy amplitude of each frequency component inside the compressor cavity at the current frame time. maximally normalizing the spectrum vector to ensure that the system can compare the energy distribution among different frequency bands under different hardware configurations. Synchronously acquire the current compressor operating frequency , based on the current compressor operating frequency Locate two key frequency bands in the frequency spectrum vector : the first band is centered on 2 times the current compressor operating frequency, and is extended by 5 Hz up and down; the second band is centered on 3 times the frequency, and is also extended by ±5 Hz; the first band and the second band together form a variable , which is used to represent the characteristic frequency area in the sound spectrum that is most relevant to the frequency resonance.

4. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The S2 specifically comprises: On the basis of the current compressor operating frequency , two perturbation frequency points are generated: upper perturbation and lower perturbation ; Real-time acquisition of new acoustic spectrum data during perturbation generates perturbation spectrum vectors, including upper perturbation spectrum vector and lower perturbation spectrum vector ; With and as the center, ±5Hz range, extract two key frequency multiplication feature segments, recorded as and , combined into the total frequency band , and in the total frequency band , compare the average energy difference between the disturbance frequency spectrum vector and the current compressor operating frequency, and construct the energy change amount after positive and negative disturbance; The mean square fluctuation amount in the high frequency band of the 0-500 Hz spectrum is statistically analyzed to construct an anti-interference term; The resonance sensitivity index is calculated according to the anti-interference term and the energy change amount , for measuring the asymmetric amplitude of the disturbance response, the greater the value represents the current frequency is more sensitive to the disturbance, and is closer to the resonance critical region.

5. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 4, wherein, The frequency modulation direction suggestion is generated as follows: Setting experience thresholds ; When the resonance susceptibility index is greater than an empirical threshold then it is determined that the current frequency has resonance risk and a frequency-avoidance process is entered, including: Frequency modulation direction The comparison between the upper and lower disturbance response amplitudes of the energy variation determines the frequency modulation direction: if the upper disturbance response amplitude is smaller than the lower disturbance response amplitude , it means that the response amplitude in the frequency increasing direction is smaller, i.e. the system is more likely to leave the resonance region after frequency increasing, so the system sets the frequency modulation direction to +1; otherwise, it is set to -1.

6. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The S3 specifically comprises: receiving the resonance sensitivity index multiplying the preset proportionality coefficient to obtain an initial frequency modulation amplitude calculating a current compressor operating frequency relative deviation from a rated frequency ; if the relative deviation exceeds a preset tolerance threshold, suppressing the initial frequency modulation amplitude to slow down the frequency modulation speed; generating a frequency modulation suggestion amplitude based on the initial frequency modulation amplitude and the relative deviation, in combination with a current compressor operating frequency to obtain a frequency modulation target frequency.

7. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 6, wherein, The S3 further comprises: The linkage control flag is triggered according to the resonance sensitivity index, which is used to indicate whether linkage control of the fan speed or the electronic expansion valve is needed, and specifically comprises: When the resonance sensitivity index is greater than a preset threshold, the system will output , linkage control flag = 1, indicating that the expansion valve / fan needs to be adjusted simultaneously.

8. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The S4 specifically comprises: Obtain the frequency modulation suggestion amplitude, with preset minimum frequency step Carry out the equal step frequency modulation, and the direction is from the current frequency modulation direction Determine, and the step is set by the PWM controller After each frequency update, return to S2 to reconstruct the latest spectrum and calculate the new resonance sensitivity index If the new resonance sensitivity index is detected after two consecutive updates exceeds the set re-resonance determination threshold, enter reverse fine tuning.

9. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 8, wherein, The reverse fine tuning specifically comprises: based on the new resonance sensitivity index , by inversely applying a scaled fine-tuning amount in the current frequency modulation direction , to obtain an inverse fine-tuning amount for exiting the new resonance boundary; wherein the inverse fine-tuning is triggered immediately when an abnormal resonance response is detected, and the new frequency is written into the controller register, and returning to S1.

10. The acoustic-sensing based variable frequency compressor resonance avoidance control method of claim 1, wherein, The controller continuously collects and processes the original acoustic signal at a sampling rate of 8000 Hz. The original acoustic signal is processed by sliding window framing with a frame length of 128 milliseconds. Each frame contains 1024 sampling points, and the frame overlap is 768 points, i.e., the frame shift is 256 points. The corresponding time interval is 32 milliseconds, which ensures continuous coverage of spectral information on the time axis.

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