Charging pile active noise reduction equipment and channel identification method thereof

Abstract

The invention discloses a charging pile active noise reduction device and a channel identification method thereof, and particularly relates to the technical field of charging pile noise reduction, and the method comprises the steps: a loudspeaker plays white noise, and an error microphone collects sound and transmits the sound to a controller; the controller uses an LMS algorithm to model a secondary channel; if the sound pressure or the power exceeds the standard, noise reduction is started; the sensor and the reference microphone provide sub-reference signals, and the error microphone inputs sound signals; the controller calculates output by using an FXLMS algorithm; and the loudspeaker emits reverse noise to counteract the noise of the charging pile. According to the method, the controller calculates the secondary channel model, the FXLMS algorithm is used for further optimizing noise control, when the noise sound pressure level or the charging power exceeds the preset value, the system automatically starts the noise reduction process, reverse noise output is adjusted in real time, the method can dynamically adapt to changes of the noise of the charging pile in different environments, and the noise control accuracy is improved. Influences caused by amplitude and phase changes in the propagation process are effectively reduced, and the stability and the efficient noise reduction effect of the active noise reduction system are ensured.

Description

Technical Field

[0001] This invention relates to the field of noise reduction technology for charging piles, and in particular to an active noise reduction device for charging piles and its channel identification method. Background Technology

[0002] With the widespread adoption of electric vehicles, charging stations, as the primary energy supply facilities for electric vehicles, have been widely used in major cities and public places. However, the noise generated by charging stations during operation, especially when charging power is high or the equipment is frequently started and stopped, often causes significant noise pollution to the surrounding environment. This noise not only affects the quality of life of nearby residents but may also cause discomfort to users. Therefore, how to effectively control and reduce the noise of charging stations during operation has become an urgent problem to be solved. Traditional noise suppression methods mostly rely on sound insulation or structural improvements, but these methods usually have certain limitations in terms of noise reduction effect and adaptability, and cannot provide continuous and effective noise suppression in different working environments and charging station operating states. With the continuous advancement of technology, active noise cancellation technology, due to its advantages in dynamic noise environments, has gradually become an important direction in the field of noise control.

[0003] Existing noise control technologies for charging piles mainly rely on physical sound insulation measures or simple noise shielding devices. While these methods can reduce noise to some extent, they usually have limited effectiveness. In particular, when the operating status of the charging pile changes, the sound insulation effect cannot be dynamically adjusted. Traditional noise suppression methods also fail to adjust in real time to the dynamic characteristics of the noise source and cannot cope with the fluctuations in noise frequency, amplitude, and phase during the operation of the charging pile. Existing technologies face significant challenges in efficiently and stably reducing the noise of charging piles, especially under varying environmental noise conditions. Traditional methods often cannot continuously optimize the noise reduction effect. At the same time, existing noise suppression technologies usually lack accurate noise source identification capabilities, resulting in the inability to accurately model the noise propagation path, which affects the accuracy and adaptability of the noise reduction effect. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an active noise reduction device for charging piles and its channel identification method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An active noise reduction device for charging piles and its channel identification method include a speed sensor, a reference microphone, an error microphone, a speaker, and a controller; The speed sensor is installed inside the charging pile and integrated into the controller to collect the speed signal of the cooling fan as a sub-reference signal. The reference microphone is installed at the air outlet of the charging pile to collect the noise emitted by the charging pile as a sub-reference signal. The error microphone is installed in the noise reduction area to collect residual noise as an error signal; The loudspeaker is installed around the charging pile to emit reverse noise to cancel out the noise from the charging pile. The controller, installed inside the charging pile, uses the input signal to generate a secondary channel model, generating reverse noise with the same amplitude but opposite phase as the noise sound wave.

[0006] The present invention is further configured such that: the frequency of the reverse noise in the controller is the same as the frequency of the charging pile noise, the amplitude of the reverse noise is equal to the amplitude of the charging pile noise, and the phase of the reverse noise is opposite to the phase of the charging pile noise.

[0007] The present invention is further configured such that: the speed sensor and the reference microphone input the collected sub-reference signals to the controller, the sub-reference signals include the fan speed signal collected by the speed sensor and the noise emitted by the charging pile collected by the reference microphone, and the controller uses a fusion method to fuse the sub-reference signals into a reference signal.

[0008] The present invention is further configured such that: the controller uses a fusion method to fuse the sub-reference signals into a reference signal. The fusion method takes into account the narrow-band characteristics of the speed sensor and the broadband characteristics of the acoustic signal, so as to better use the reference signal to reflect the noise characteristics of the charging pile.

[0009] The present invention is further configured to include the following steps: S1. Before noise reduction begins, the speaker plays white noise, which propagates through the secondary channel to the error microphone. S2. The error microphone collects the white noise after passing through the secondary channel and inputs it to the controller; S3. The controller uses the LMS algorithm to calculate the secondary channel model; S4. Noise reduction begins when the sound pressure level or charging power exceeds the preset value. S5, the speed sensor, and the reference microphone input the collected sub-reference signals to the controller; S6. The error microphone inputs the collected sound signal to the controller; S7. The controller uses the FXLMS algorithm to calculate the output; S8: The speaker emits reverse noise to cancel out the charging pile noise.

[0010] The present invention is further configured such that: in step S1, before the noise reduction begins, the speaker plays white noise, which propagates through the secondary channel to the error microphone. The secondary channel includes peripheral circuits, electroacoustic equipment and physical acoustic paths. The signal propagating in the secondary channel will produce changes in amplitude and phase.

[0011] The present invention is further configured such that: the secondary channel model is a finite impulse response filter, used to estimate the secondary channel and compensate for errors caused by signal propagation in the secondary channel.

[0012] The present invention is further configured such that: in step S4, when the sound pressure level or charging power exceeds a preset value, noise reduction begins. S4.1 The controller collects residual noise sound pressure level and charging power in real time; S4.2 Determine whether the residual noise sound pressure level is greater than the preset sound pressure level value; S4.3 If so, proceed to step S4.8; S4.4 If not, proceed to step S4.5; S4.5 Determine whether the charging power is greater than the preset power value; S4.6 If not, proceed to step S4.1; S4.7 If so, proceed to step S4.8; S4.8, Enable Active Noise Cancellation.

[0013] The present invention is further configured such that: the preset sound pressure level value takes into account that the ambient noise during the day is greater than that at night, the preset sound pressure level value is set to 60dB from 6:00 to 22:00 and to 50dB from 22:00 to 6:00.

[0014] The present invention is further configured such that: the power preset value is set in consideration of the complete process of DC fast charging pile charging, and a high-power charging stage with constant current and gradually increasing voltage is selected, and the power preset value is usually set to 50kW-100kW.

[0015] The beneficial effects of this invention are as follows: This invention achieves active noise reduction of charging pile noise by integrating a speed sensor, a reference microphone, an error microphone, a speaker, and a controller. The signals collected by the speed sensor and the reference microphone are input to the controller, and after fusion processing, a precise reference signal is formed. The controller calculates the reverse noise with the opposite phase and equal amplitude to the charging pile noise based on this signal, and emits it through the speaker, thereby effectively canceling the noise generated by the charging pile. The device can respond to the working status of the charging pile in real time. Especially when the charging pile noise changes, it continuously adjusts the reverse noise to ensure the stability and optimization of the noise reduction effect, greatly reducing environmental noise pollution.

[0016] This invention identifies secondary channels in the noise propagation process of charging piles using the LMS algorithm, thereby accurately modeling the noise propagation path. By playing white noise before noise reduction is initiated, the signal collected by the error microphone is input to the controller, which calculates the secondary channel model and further optimizes noise control using the FXLMS algorithm. When the noise sound pressure level or charging power exceeds a preset value, the system automatically initiates the noise reduction process and adjusts the reverse noise output in real time. This method can dynamically adapt to changes in charging pile noise under different environments, effectively reducing the impact of amplitude and phase changes during propagation, and ensuring the stability and efficient noise reduction effect of the active noise reduction system. Attached Figure Description

[0017] Figure 1 This is a schematic block diagram of an active noise reduction device for charging piles provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the active noise reduction method provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the switching principle of an active noise cancellation device provided in an embodiment of the present invention; Figure 4 A schematic diagram of the LMS algorithm provided in this embodiment of the invention; Figure 5 This is a schematic diagram of the FxLMS algorithm provided in an embodiment of the present invention; Figure 6 The diagram illustrates the noise reduction effect provided in an embodiment of the present invention.

[0018] Legend 101. Controller; 102. Reference microphone; 103. Error microphone; 104. Speaker; 105. Speed ​​sensor. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of this application, not all of them. The specific embodiments described herein are only used to explain the invention and are not intended to limit the invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be further noted that the accompanying drawings and embodiments of the present invention mainly describe the concept of the present invention. Based on this concept, some specific forms and arrangements of connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be fully described. However, under the premise that those skilled in the art understand the concept of the present invention, they can implement the above-mentioned specific forms and arrangements in a well-known manner.

[0021] When a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0022] The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself. The terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0023] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, and the spatial relative descriptions used herein will be interpreted accordingly.

[0024] 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, and "several" means one or more, unless otherwise explicitly specified.

[0025] The present invention will now describe an active noise reduction device for charging piles and its channel identification method.

[0026] Example 1 like Figure 1 As shown, an active noise reduction device for charging piles includes a speed sensor 105, a reference microphone 102, an error microphone 103, a speaker 104, and a controller 101. The speed sensor 105 is installed inside the charging pile and integrated into the controller 101 to collect the speed signal of the cooling fan as a sub-reference signal; Reference microphone 102 is installed at the air outlet of the charging pile to collect the noise emitted by the charging pile as a sub-reference signal; An error microphone 103 is installed in the noise reduction area to collect residual noise as an error signal; Speaker 104 is installed around the charging station to emit reverse noise to cancel out the noise from the charging station. The controller 101 is installed inside the charging pile and uses the input signal to generate a secondary channel model, generating reverse noise with the same amplitude but opposite phase as the noise sound wave. The frequency of the reverse noise in controller 101 is the same as the frequency of the charging pile noise, the amplitude of the reverse noise is equal to the amplitude of the charging pile noise, and the phase of the reverse noise is opposite to the phase of the charging pile noise. The speed sensor 105 and the reference microphone 102 input the collected sub-reference signals to the controller 101. The sub-reference signals include the fan speed signal collected by the speed sensor 105 and the noise emitted by the charging pile collected by the reference microphone 102. The controller 101 uses a fusion method to fuse the sub-reference signals into a reference signal. The controller 101 uses a fusion method to fuse the sub-reference signals into a reference signal. The fusion method takes into account the narrow-band characteristics of the speed sensor 105 and the wide-band characteristics of the acoustic signal, and better uses the reference signal to reflect the noise characteristics of the charging pile.

[0027] In the above embodiment, the controller 101 is installed inside the charging pile and uses the input signal to generate a secondary channel model, generating reverse noise with the same amplitude and opposite phase as the noise sound wave; the reference microphone 102 is installed at the air outlet of the charging pile to collect the noise emitted by the charging pile as a sub-reference signal; the error microphone 103 is installed in the noise reduction area to collect the residual noise as an error signal; and the speaker 104 is installed around the charging pile to emit reverse noise to cancel the noise of the charging pile.

[0028] Example 2 like Figure 2 , Figure 5 and Figure 6 As shown, a method for identifying active noise reduction channels in charging piles includes the following steps: S1. Before noise reduction begins, speaker 104 plays white noise, which propagates through the secondary channel to reach error microphone 103. S2. Error microphone 103 collects white noise after passing through the secondary channel and inputs it to controller 101; S3, Controller 101 uses the LMS algorithm to calculate the secondary channel model; S4. Noise reduction begins when the sound pressure level or charging power exceeds the preset value. S5, the speed sensor 105, and the reference microphone 102 input the collected sub-reference signals to the controller 101; S6. Error microphone 103 inputs the collected sound signal to controller 101; S7, Controller 101 uses the FXLMS algorithm to calculate the output; S8 and speaker 104 emit reverse noise to cancel out the charging pile noise.

[0029] In the above embodiment, before noise reduction begins, the speaker 104 plays white noise, which propagates through the secondary channel to the error microphone 103; the error microphone 103 collects the white noise after passing through the secondary channel and inputs it to the controller 101; the controller 101 uses the LMS algorithm to calculate the secondary channel model; when the sound pressure level or charging power exceeds a preset value, noise reduction begins; the speed sensor 105 and the reference microphone 102 input the collected sub-reference signals to the controller 101; the error microphone 103 inputs the collected sound signals to the controller 101; the controller 101 uses the FXLMS algorithm to calculate the output; the speaker 104 emits reverse noise to cancel the charging pile noise.

[0030] In active noise control, since the signal is in the secondary channel... The amplitude and phase change during propagation, directly affecting the stability and noise reduction performance of the algorithm. Therefore, a secondary channel estimation needs to be added between the reference signal and the filter coefficient update algorithm. That is, using secondary channel estimation For reference signal Filtering is performed, and the LMS algorithm is improved to the FxLMS algorithm. The real channel is simplified to a length of... The FIR filter has a coefficient vector of... ; Control Filter Output as well as The noise reduction signal reaches the error microphone 103 via the secondary channel. It can be expressed by the following formula: ; ; Primary noise and noise immunity are canceled out at error microphone 103, leaving the residual noise as follows: ; Calculate the gradient vector of the cost function at time n. : ; The selected iteration step size is very small, therefore the filter coefficients can be considered... If updates are slow within a sufficiently short timeframe, then: ; Substitution get ; In the formula The reference signal is after secondary channel filtering; substituting it into the steepest descent method... The iterative update formula is obtained as follows: ; Comparing the iterative update formula of the LMS algorithm, it is found that the FxLMS algorithm considering secondary channel modeling uses... Replace the original expression Therefore, the secondary channel is estimated. Placed in reference signal The LMS algorithm can effectively cancel out the changes in amplitude and phase caused by the secondary channel.

[0031] in: Figure 6 This diagram illustrates the noise reduction effect of the charging pile noise reduction system according to an embodiment of the present invention. A control system was built using a ZYNQ 7000 series development board, a PCB 130E20 microphone, and a HiVi S5N speaker to reduce charging pile noise. After the active noise cancellation system was activated, the noise reduction at 638Hz reached 26.2dB(A), the noise reduction at 1018Hz reached 17.4dB(A), and the overall frequency band control effect reached 4.3dB(A). Therefore, the charging pile noise reduction system of this embodiment can effectively suppress charging pile noise.

[0032] Example 3 like Figure 3 and 4 As shown, a method for identifying active noise reduction channels in charging piles includes step S4, where noise reduction begins when the sound pressure level or charging power exceeds a preset value. S4.1, Controller 101 collects residual noise sound pressure level and charging power in real time; S4.2 Determine whether the residual noise sound pressure level is greater than the preset sound pressure level value; S4.3 If so, proceed to step S4.8; S4.4 If not, proceed to step S4.5; S4.5 Determine whether the charging power is greater than the preset power value; S4.6 If not, proceed to step S4.1; S4.7 If so, proceed to step S4.8; S4.8, Enable Active Noise Cancellation.

[0033] In the above embodiments, the secondary channel refers to the acoustic path through which the electrical signal output from the filter propagates through the air to the noise reduction location. This path consists of three parts: peripheral circuits including a digital filter and a power amplifier; the physical acoustic path from the speaker 104 to the error microphone 103; and electroacoustic equipment including the speaker 104 and the error microphone 103. Due to the continuous attenuation of sound waves during propagation and the non-flat amplitude-frequency response characteristics of the power amplifier and speaker 104, the amplitude and phase of the signal will change when propagating in the secondary channel, directly affecting the stability of the algorithm and the noise reduction performance. Therefore, secondary channel identification using the LMS algorithm is a necessary step before active noise reduction control.

[0034] The LMS algorithm is an adaptive filtering method based on gradient descent, used to minimize the instantaneous squared value of the error signal. In an active noise control system, let the reference signal vector be: ; The filter coefficient vector of length L is: ; The filter output at time n can be expressed as: ; The noise collected at the error signal is: ; Where d(n) is the desired signal, the mean square error criterion is used for filter optimization, and the cost function is: ; in, ; ; The cost function can be seen It is the filter coefficient vector The quadratic function, for The gradient vector can be obtained by taking the partial derivative: ; make = 0, thus obtaining the optimal weight vector: ; However, due to the positions of the cross-correlation matrix P and the autocorrelation matrix Q, the optimal weight vector cannot be obtained directly through calculation. Therefore, the steepest descent method is used to iteratively obtain the filter coefficient vector at time n+1 using the filter coefficient vector and gradient vector at time n: ; Among them, to ensure the convergence step size of the algorithm The range of values ​​for is as follows: ; Working principle: When in use, the device integrates a speed sensor 105, a reference microphone 102, an error microphone 103, a speaker 104, and a controller 101. The speed sensor 105 is used to detect the speed of the cooling fan inside the charging pile, serving as a sub-reference signal. At the same time, the reference microphone 102 is used to collect the noise emitted by the charging pile, which is also one of the sub-reference signals. After these signals are transmitted to the controller 101, an accurate reference signal is generated through a fusion algorithm. Taking into account the broadband characteristics of the fan speed signal and the noise, the noise characteristics of the charging pile are better characterized. Based on these signals, the controller 101 calculates the reverse noise with the opposite phase and equal amplitude to the noise, which is emitted through the speaker 104 to achieve the noise reduction effect.

[0035] In the specific implementation of noise reduction, the system first plays white noise through speaker 104. After propagating through the secondary channel of the charging pile, the error microphone 103 collects the white noise after passing through the secondary channel. This signal is input to controller 101, which uses the LMS algorithm to calculate the secondary channel model. When the charging power or noise sound pressure level reaches a preset threshold, the noise reduction process starts. Controller 101 uses the FXLMS algorithm, based on the real-time collected sub-reference signal and the feedback signal from error microphone 103, to adjust the reverse noise emitted by speaker 104, thereby effectively canceling the noise generated by the charging pile. In this way, the system can adapt to changes in charging pile noise in real time under various environments, achieving continuous optimization of the noise reduction effect.

[0036] The noise reduction system also adaptively adjusts according to changes in charging pile noise. When the residual noise sound pressure level or charging power exceeds the set threshold, the system will reactivate the active noise reduction function. The controller 101 will monitor the residual noise sound pressure level and charging power in real time and determine whether the conditions for starting noise reduction are met. By continuously acquiring new signals and optimizing through algorithms, the controller 101 can accurately adjust the amplitude and phase of the output reverse noise to ensure the best noise reduction effect. During the noise reduction process, the system accurately estimates the characteristics of the secondary channel through the secondary channel identification method, thereby reducing the impact of phase and amplitude changes during signal propagation and ensuring the stability of the algorithm and the noise reduction effect.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

Claims

1. An active noise reduction device for charging piles, characterized in that, It includes a speed sensor (105), a reference microphone (102), an error microphone (103), a speaker (104), and a controller (101). The speed sensor (105) is installed inside the charging pile and integrated into the controller (101) to collect the speed signal of the cooling fan as a sub-reference signal; The reference microphone (102) is installed at the air outlet of the charging pile to collect the noise emitted by the charging pile as a sub-reference signal; The error microphone (103) is installed in the noise reduction area to collect residual noise as an error signal; The loudspeaker (104) is installed around the charging pile to emit reverse noise to cancel out the noise of the charging pile. The controller (101) is installed inside the charging pile and uses the input signal to generate a secondary channel model. At the same time, during the noise control stage, it generates reverse noise with the same amplitude and opposite phase as the noise sound wave.

2. The active noise reduction device for charging piles according to claim 1, characterized in that: The frequency of the reverse noise in the controller (101) is the same as the frequency of the charging pile noise, the amplitude of the reverse noise is equal to the amplitude of the charging pile noise, and the phase of the reverse noise is opposite to the phase of the charging pile noise.

3. The active noise reduction device for charging piles according to claim 1, characterized in that: The speed sensor (105) and reference microphone (102) input the collected sub-reference signals to the controller (101). The sub-reference signals include the fan speed signal collected by the speed sensor (105) and the noise emitted by the charging pile collected by the reference microphone (102). The controller (101) uses a fusion method to fuse the sub-reference signals into a reference signal.

4. The active noise reduction device for charging piles according to claim 1, characterized in that: The controller (101) uses a fusion method to fuse the sub-reference signals into a reference signal. The fusion method takes into account the narrow-band characteristics of the speed sensor (105) and the broadband characteristics of the acoustic signal, and better uses the reference signal to reflect the noise characteristics of the charging pile.

5. A method for identifying active noise reduction channels in charging piles, characterized in that, Includes the following steps: S1. Before noise reduction begins, the speaker (104) plays white noise, which is propagated through the secondary channel to the error microphone (103); S2. Error microphone (103) collects white noise after passing through the secondary channel and inputs it to controller (101). S3, the controller (101) uses the LMS algorithm to calculate the secondary channel model; S4. Noise reduction begins when the sound pressure level or charging power exceeds the preset value. S5. The speed sensor (105) and the reference microphone (102) input the collected sub-reference signals to the controller (101). S6. The error microphone (103) inputs the collected sound signal to the controller (101). S7, The controller (101) uses the FXLMS algorithm to calculate the output; S8, the speaker (104) emits reverse noise to cancel out the charging pile noise.

6. The method for identifying active noise reduction channels in charging piles according to claim 5, characterized in that: In step S1, before noise reduction begins, the speaker (104) plays white noise, which propagates through the secondary channel to the error microphone (103). The secondary channel includes peripheral circuits, electroacoustic equipment, and physical acoustic paths. The signal propagating in the secondary channel will produce changes in amplitude and phase.

7. The method for identifying active noise reduction channels in charging piles according to claim 6, characterized in that: The secondary channel model is a finite impulse response filter used to estimate the secondary channel and compensate for errors caused by signal propagation in the secondary channel.

8. The method for identifying active noise reduction channels in charging piles according to claim 5, characterized in that: In step S4, if the sound pressure level or charging power exceeds a preset value, noise reduction begins. S4.1 The controller (101) collects the residual noise sound pressure level and charging power in real time; S4.2 Determine whether the residual noise sound pressure level is greater than the preset sound pressure level value; S4.3 If so, proceed to step S4.8; S4.4 If not, proceed to step S4.5; S4.5 Determine whether the charging power is greater than the preset power value; S4.6 If not, proceed to step S4.1; S4.7 If so, proceed to step S4.8; S4.8, Enable Active Noise Cancellation.

9. The method for identifying active noise reduction channels in charging piles according to claim 8, characterized in that: The preset sound pressure level value takes into account that the ambient noise during the day is greater than that at night. The preset sound pressure level value is set to 60dB from 6:00 to 22:00 and 50dB from 22:00 to 6:

00.

10. The method for identifying active noise reduction channels in charging piles according to claim 8, characterized in that, The power preset value is set with consideration of the complete charging process of DC fast charging piles. The high-power charging stage with constant current and gradually increasing voltage is selected. The power preset value is usually set to 50kW-100kW.

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