Charging pile mute air duct heat dissipation device and method

Abstract

The application is suitable for the technical field of charging pile heat dissipation, and provides a charging pile mute air duct heat dissipation device and method, wherein a charging pile mute air duct heat dissipation method comprises the following steps: S1, calculating the cooling mass flow required for eliminating redundant heat to maintain the target temperature rise; S2, based on the cooling mass flow and the geometric fluid mechanics characteristics of the air duct, dynamically adjusting the optimal deflection angle of the guide vane in the air duct, and calculating the target air pressure required for overcoming the resistance along the air duct and the local resistance; S3, combining the aerodynamic characteristics of the impeller machine, converting the target air pressure and the cooling mass flow into the optimal control instruction of the fan rotating speed, and calculating the optimal rotating angular velocity of the fan which balances the work and the noise. The application can accurately control the rotating speed of the fan, realizes the collaborative optimization of the heat dissipation demand, the energy consumption and the noise, and avoids the problems of low-efficiency heat dissipation or excessive noise caused by the traditional fixed rotating speed or rough speed regulation mode.

Description

Technical Field

[0001] This invention belongs to the field of charging pile heat dissipation technology, and particularly relates to a silent air duct heat dissipation device and method for charging piles. Background Technology

[0002] With the rapid popularization of new energy vehicles, the installed capacity of DC fast charging piles continues to rise. High-power charging modules generate a large amount of heat during operation, requiring forced air cooling systems to maintain their normal operating temperature. Current mainstream charging pile cooling solutions typically employ a fixed air duct structure combined with axial fans to continuously blow air away the heat from the charging modules. However, this approach has revealed a series of inherent flaws in practical engineering applications.

[0003] First, most of the fans in the existing charging pile cooling systems operate at a constant speed or in a simple step-by-step speed regulation mode. The cooling air volume is only roughly switched according to the temperature threshold. It is impossible to continuously adjust the cooling medium flow rate according to the real-time heat generation of the charging module and the ambient thermodynamic conditions. This results in the fans running at full speed continuously under low load conditions, generating unnecessary noise, while the insufficient air volume under high load conditions restricts the charging power output.

[0004] Secondly, the angle of the guide vanes in existing duct designs is usually fixed during production and assembly, lacking the ability to dynamically adjust the vane deflection angle according to actual operating conditions to optimize airflow distribution. When changes in fan speed cause significant fluctuations in Reynolds number, the fixed-angle guide vanes cannot maintain the optimal airflow adhesion state, resulting in a sharp increase in local duct resistance, further exacerbating the fan's workload and aerodynamic noise radiation.

[0005] In addition, existing charging piles only deal with the aerodynamic noise of wind turbines by passively using sound-absorbing cotton or sound insulation boards. They lack active noise reduction methods that extract the acoustic fundamental frequency based on the rotational characteristics of the wind turbine blades and implement active noise cancellation. The noise control effect is limited and it is difficult to adapt to the noise spectrum shift caused by changes in wind turbine speed.

[0006] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0007] The purpose of this invention is to provide a case name that addresses the aforementioned problems.

[0008] This invention is implemented as follows: a method for silent air duct heat dissipation in charging piles, comprising the following steps:

[0009] S1. Obtain the current real-time operating status of the charging module and the environmental thermodynamic conditions, and calculate the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise.

[0010] S2. Based on the cooling mass flow rate and the geometric fluid dynamics characteristics of the air duct, dynamically adjust the optimal deflection angle of the guide vanes in the air duct, and calculate the target air pressure required to overcome the resistance along the air duct and local resistance.

[0011] S3. Combining the aerodynamic characteristics of the impeller, the target wind pressure and cooling mass flow rate are converted into the optimal control command for the fan speed, and the optimal rotational angular velocity of the fan that balances work and noise is calculated.

[0012] S4. Extract acoustic features based on the optimal rotational angular velocity of the fan, and generate the phase and amplitude of the active noise cancellation compensation signal in reverse based on the aeroacoustic radiation model to drive the acoustic device to cancel the low-frequency noise in the heat dissipation duct.

[0013] In a further technical solution, in step S1, the specific method for calculating the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise is as follows: First, calculate the difference obtained by multiplying by one and subtracting the power conversion efficiency by the real-time active power of the charging module to obtain the total heat generation power of the charging module; then calculate the difference obtained by subtracting the ambient temperature from the current temperature of the charging module and divide it by the thermal resistance of the module to obtain the natural heat dissipation power; subtract the natural heat dissipation power from the total heat generation power to obtain the forced heat dissipation power required.

[0014] The target temperature rise limit is then calculated by subtracting the temperature protection constant to obtain the effective allowable temperature rise. The specific heat capacity of the air at constant pressure is multiplied by this effective allowable temperature rise to obtain the heat capacity of the cooling medium. The required forced heat dissipation power is divided by the heat capacity of the cooling medium, and the quotient is used as the cooling mass flow rate.

[0015] A further technical solution is to calculate the flow velocity of the duct cross section by dividing the cooling mass flow rate by the product of the air density and the duct cross section area, and using the quotient as the flow velocity of the duct cross section.

[0016] A further technical solution involves calculating the optimal deflection angle of the guide vane as follows: First, calculate the air density multiplied by the flow velocity of the duct section, then multiply by the hydraulic diameter of the duct, and then divide by the aerodynamic viscosity to obtain the Reynolds number; then, take the negative value of the Reynolds number and multiply it by the dimensionless empirical fitting coefficient, use this product as the exponent and the natural constant e as the base to calculate the exponential function value, subtract the exponential function value from 1, and then multiply it by the maximum allowable deflection angle of the duct vane. The resulting product is taken as the optimal deflection angle of the guide vane.

[0017] A further technical solution involves calculating the target air pressure of the heat dissipation duct as follows: First, calculate the friction coefficient of the duct, multiply it by the duct length, and then divide it by the hydraulic diameter of the duct to obtain the friction coefficient term. Next, calculate the sum of the local resistance coefficient of the duct foundation divided by the sine of the optimal deflection angle of the guide vanes and the deflection protection constant, and the quotient is the local resistance term. Add the friction coefficient term and the local resistance term together, and then multiply it by the product of half the air density and the square of the flow velocity at the duct cross-section. The result is taken as the target air pressure required for the heat dissipation duct.

[0018] A further technical solution is that the optimal rotational angular velocity of the wind turbine is calculated as follows:

[0019] First, calculate the quotient of the target wind pressure divided by the air density, the square of the fan impeller radius, and the dimensionless total pressure coefficient to obtain the first square term; then calculate the quotient of the cooling mass flow rate divided by the air density, the cube of the fan impeller radius, and the dimensionless flow coefficient, and square this quotient to obtain the second square term; add the first square term and the second square term and take the square root, and the result is taken as the optimal rotational angular velocity of the fan.

[0020] A further technical solution is that the phase offset of the active noise cancellation compensation signal is calculated as follows:

[0021] First, calculate the optimal rotational angular velocity of the wind turbine, multiply it by the number of wind turbine blades, then multiply it by the distance from the secondary sound source to the noise-canceling microphone, and then divide it by the ambient sound speed to obtain the first phase delay term. Next, calculate the optimal rotational angular velocity of the wind turbine, multiply it by the number of wind turbine blades, then multiply it by the distance from the primary sound source to the noise-canceling microphone, and then divide it by the ambient sound speed to obtain the second phase delay term. Add the first phase delay term to pi and subtract the second phase delay term to obtain the original phase value. Then, add or subtract an integer multiple of pi to this original phase value to make it fall within the range of zero to twice pi, which is used as the phase offset of the noise-canceling signal.

[0022] A further technical solution is that the sound pressure amplitude of the active noise cancellation compensation signal is calculated as follows:

[0023] First, take the cube of the optimal rotational angular velocity of the fan, then multiply it by the cube of the fan impeller radius, and then multiply it by the air density to obtain the numerator. Divide the numerator by the ambient sound speed to obtain the basic sound pressure amplitude. Then multiply this basic sound pressure amplitude by the acoustic proportional gain coefficient to obtain the compensated sound pressure amplitude of the noise-cancelling signal.

[0024] A silent air duct heat dissipation device for charging piles, applied to the method described in any of the above-mentioned embodiments, comprising:

[0025] The control unit is used to acquire the real-time operating status of the charging module and the environmental thermodynamic conditions, and output cooling mass flow rate demand signal, guide vane deflection control signal, fan speed control signal and active noise cancellation compensation signal.

[0026] The air duct body is located on the heat dissipation path of the charging module, and the air duct body is provided with rotatable guide vanes.

[0027] The drive mechanism is connected to the guide vane and receives the deflection control signal of the guide vane to adjust the deflection angle of the guide vane;

[0028] A fan is installed at the air inlet or air outlet of the air duct body and receives the fan speed control signal to adjust the rotational angular velocity.

[0029] An acoustic noise reduction unit is located near the air duct body and receives the active noise cancellation compensation signal to generate an anti-phase sound wave to cancel low-frequency noise.

[0030] The control unit is communicatively connected to the drive mechanism, the fan, and the acoustic noise reduction unit, respectively.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention achieves coordinated optimization of heat dissipation requirements, energy consumption, and noise by acquiring the real-time operating status of the charging module and environmental thermodynamic conditions, dynamically calculating the required cooling mass flow rate, and combining the geometric characteristics of the air duct and the mechanical aerodynamic characteristics of the impeller to precisely control the fan speed. This avoids the problems of inefficient heat dissipation or excessive noise caused by traditional fixed speed or coarse speed adjustment methods.

[0033] This invention dynamically adjusts the optimal deflection angle of the guide vanes based on the Reynolds number, so that the airflow in the duct always maintains the optimal wall attachment state, effectively reducing local resistance and airflow separation loss, reducing the power load of the fan and aerodynamic noise radiation, and significantly improving the duct flow efficiency and the overall energy efficiency of the heat dissipation system.

[0034] This invention extracts the acoustic features corresponding to the optimal rotational angular velocity of the wind turbine and combines them with an aeroacoustic radiation model to generate the phase and amplitude of an active noise cancellation compensation signal. This allows the wind turbine to dynamically adapt to the noise spectrum shift caused by changes in wind turbine speed, achieving precise active cancellation of low-frequency noise, significantly reducing the operating noise of charging piles, and improving the user experience.

[0035] This invention organically integrates cooling mass flow rate calculation, dynamic deflection control of guide vanes, fan speed optimization, and active noise cancellation technology to form a closed-loop collaborative control system. It can adaptively adjust the operating parameters of the heat dissipation system across the entire operating range, ensuring thermal management safety during high-power charging while also meeting the need for quiet operation under low-load conditions, significantly improving the environmental adaptability and overall performance of the charging pile. Attached Figure Description

[0036] Figure 1 This is a content framework diagram of the overall solution;

[0037] Figure 2 Graph showing the calculation of cooling mass flow rate and duct cross-sectional velocity;

[0038] Figure 3 Diagram showing the calculation of wind turbine control parameters and the solution of target wind pressure;

[0039] Figure 4 The control logic diagram for generating active noise reduction signals. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages 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 specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0042] like Figures 1-4 As shown, a silent air duct heat dissipation method for charging piles, provided in one embodiment of the present invention, includes the following steps:

[0043] S1. Obtain the current real-time operating status and environmental thermodynamic conditions of the charging module, and calculate the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise.

[0044] Specifically, obtaining the real-time operating status and environmental thermodynamic conditions of the charging module can be achieved by deploying temperature sensors and power sensors inside and outside the charging module to collect data in real time. For example, temperature sensors can be thermistors or thermocouples, and power sensors can be Hall effect sensors. These sensors convert the collected analog signals into digital signals and transmit them to the control unit via a data bus. Alternatively, communication with the charging pile's central control system via a data interface can be used, allowing the central control system to provide the charging module's operating parameters and environmental monitoring data. Calculating the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise can be done using preset empirical formulas or lookup tables. For example, an experimental relationship between the charging module's heat generation and cooling mass flow rate can be established and stored in a lookup table. Once the real-time operating status and environmental conditions are obtained, the corresponding cooling mass flow rate can be retrieved directly from the lookup table. Another approach is to estimate the cooling mass flow rate using simplified heat balance equations. For example, the charging module can be considered a heat source, and the required cooling mass flow rate can be roughly calculated using parameters such as its heat output, allowable temperature rise, and the specific heat capacity of the cooling medium.

[0045] S2. Based on the cooling mass flow rate and the geometric fluid dynamics characteristics of the air duct, dynamically adjust the optimal deflection angle of the guide vanes in the air duct, and calculate the target wind pressure required to overcome the resistance along the air duct and local resistance.

[0046] Specifically, dynamically adjusting the optimal deflection angle of the guide vanes within the duct can be achieved through a preset control strategy. For example, based on the cooling mass flow rate, the duct vane deflection angle can be divided into several levels. When the cooling mass flow rate is at a certain level, the guide vanes are adjusted to the corresponding preset angle. Alternatively, adjustment can be achieved through a mapping relationship established based on fluid simulation or experimental data. For instance, under different cooling mass flow rates, CFD simulations or wind tunnel experiments can be used to determine the vane deflection angle that minimizes duct resistance or optimizes airflow distribution, and this data can be stored as control parameters. Calculating the target air pressure required to overcome duct friction and local resistance can be done using empirical formulas or simplified models. For example, the duct can be considered as a series of series-connected resistance elements; friction resistance and local resistance can be calculated separately, then superimposed to obtain the total resistance, which can then be converted into the required air pressure. Another approach is to estimate using a lookup table. For example, based on the duct structure, cooling mass flow rate, and guide vane deflection angle, a pre-established correspondence between air pressure requirements and these parameters can be stored in a lookup table.

[0047] S3. Combining the aerodynamic characteristics of the impeller, the target wind pressure and cooling mass flow rate are converted into the optimal control command for the fan speed, and the optimal rotational angular velocity of the fan that balances work and noise is calculated.

[0048] Specifically, converting the target air pressure and cooling mass flow rate into optimal control commands for the fan speed can be achieved using the fan's performance curves. For example, based on the fan performance curves (such as the PQ curve) provided by the fan manufacturer, the corresponding fan speed can be determined given the target air pressure and cooling mass flow rate. Alternatively, estimation can be performed using a simplified fan model. For instance, based on the similarity law of fans, the required speeds to achieve the target air pressure and cooling mass flow rate at different speeds can be calculated using known fan performance data at a given speed. The optimal fan rotational angular velocity, balancing work and noise, can be calculated using a pre-defined optimization algorithm. For example, while meeting heat dissipation requirements, an iterative search or gradient descent algorithm can be used to find a balance between the fan performance curve and the noise characteristic curve, ensuring that the fan provides the required airflow and pressure while maintaining acceptable energy consumption and noise levels. Another approach is to use multi-objective optimization methods. For example, by taking wind turbine energy consumption and noise as two optimization objectives, an optimal wind turbine rotational angular velocity can be determined through methods such as weighted summation or Pareto optimization to achieve a comprehensive balance between energy consumption and noise.

[0049] S4. Extract acoustic features based on the optimal rotational angular velocity of the fan, and generate the phase and amplitude of the active noise cancellation compensation signal in reverse based on the aeroacoustic radiation model to drive the acoustic device to cancel the low-frequency noise in the heat dissipation duct.

[0050] Specifically, acoustic features can be extracted based on the optimal rotational angular velocity of the wind turbine, which can be done using a pre-established acoustic database. For example, the noise spectrum generated by the wind turbine can be experimentally measured and stored at different turbine speeds. Once the optimal rotational angular velocity of the wind turbine is determined, the corresponding noise acoustic features can be retrieved from the database. Alternatively, a simplified acoustic model can be used for prediction. For example, the main frequency components and approximate sound pressure level of the wind turbine noise can be estimated based on parameters such as the number of turbine blades and its rotational speed. The phase and amplitude of the active noise cancellation compensation signal can be generated based on the aeroacoustic radiation model, which can be achieved using digital signal processing techniques. For example, based on the extracted noise acoustic features, a compensation signal with the same frequency and amplitude as the original noise but with an opposite phase can be generated using algorithms such as digital filters or Fourier transforms. Another approach is to use adaptive algorithms. For example, the LMS (Least Mean Square) algorithm or other adaptive filtering algorithms can be used to monitor the noise in the duct in real time and dynamically adjust the phase and amplitude of the compensation signal to achieve noise reduction. To counteract low-frequency noise within the cooling duct, acoustic devices can be driven to produce inverted sound waves. This can be achieved by amplifying the generated compensation signal using a power amplifier, and then driving the device, such as a loudspeaker, to emit these inverted sound waves. For example, the compensation signal can be input to a D / A converter, converted to an analog signal, and then used to drive a loudspeaker mounted near the duct via an audio amplifier. Alternatively, inverted sound waves can be generated using piezoelectric ceramics or other miniature acoustic actuators integrated into the duct structure. For instance, the compensation signal can be directly applied to a piezoelectric ceramic sheet, causing it to vibrate and produce sound waves.

[0051] Through the synergistic effect of the above steps, this method can dynamically optimize the operating parameters of the heat dissipation system according to the real-time heat load of the charging module and environmental conditions. This not only ensures the heat dissipation of the charging module, but also reduces operating noise through active noise reduction technology, achieving the goal of silent heat dissipation.

[0052] In a preferred embodiment of the present invention, in step S1, the calculation of the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise is specifically calculated using the following formula:

[0053]

[0054] in, Indicates the cooling mass flow rate. This represents the real-time active power of the charging module, and η represents the energy conversion efficiency. This indicates the current temperature of the charging module. Indicates ambient temperature. Indicates the module's thermal resistance. This indicates the specific heat capacity of air at constant pressure. Indicates the upper limit of the target temperature rise; This represents a small constant for temperature protection. The dimension of is K, and its value is less than . Typically, the value is 0.5 K to 2 K.

[0055] In this embodiment, the cooling mass flow rate It represents the mass of cooling medium (usually air) that needs to flow through the heat dissipation duct per unit time. It is a key parameter for measuring the cooling capacity requirements of a heat dissipation system.

[0056] Real-time active power of charging module This refers to the actual electrical power consumed by the charging module in its current operating state, most of which is converted into heat and dissipated. This parameter can be obtained in real time by the power sensor inside the charging module, or calculated by the charging pile's control unit based on the charging current and voltage.

[0057] The energy conversion efficiency η represents the efficiency with which a charging module converts input electrical energy into output electrical energy; unconverted energy is dissipated as heat. This efficiency value can be obtained from the design specifications of the charging module or through experimental testing, or it can be dynamically estimated under different load conditions.

[0058] Current temperature of charging module This refers to the real-time temperature of the core components of the charging module, typically monitored by temperature sensors integrated inside or on the surface of the module. Ambient temperature. This refers to the temperature of the external environment where the charging station is located, which is usually obtained through an external ambient temperature sensor.

[0059] Module thermal resistance This represents the resistance of the charging module to passive heat dissipation from the surrounding environment; the higher the value, the worse the passive heat dissipation capability. This parameter is usually determined through thermal design analysis or experimental measurement.

[0060] specific heat capacity of air at constant pressure This refers to the amount of heat required to raise the temperature of a unit mass of air by a unit temperature under constant pressure. This value can be found in tables or taken as an empirical constant based on the composition and temperature of the air; for example, it can be taken as approximately 1005 J / (kg·K) at normal temperature and pressure.

[0061] Target temperature rise ceiling This refers to the maximum allowable temperature rise of the charging module after cooling air flows through it, designed to ensure the charging module operates within a safe and efficient temperature range. This value is typically set by the charging module manufacturer based on its thermal design specifications and reliability requirements. Temperature protection microconstant. It is a tiny temperature value used to provide a safety margin, and its value is less than... It is typically between 0.5K and 2K. This constant is introduced to prevent the system from approaching the theoretical limit too closely during calculation, thus providing additional protection against uncertainties or transient fluctuations in actual operation.

[0062] In a preferred embodiment of the present invention, the formula for calculating the flow velocity at the cross-section of the air duct is as follows:

[0063]

[0064] in, The velocity at the cross-section of the air duct is represented by ρ, and the air density is represented by ρ. This indicates the cross-sectional area of ​​the air duct.

[0065] In this embodiment, the flow velocity at the cross-section of the air duct This refers to the average velocity of air across the cross-section of the duct. This parameter is a key indicator for evaluating the airflow state within the duct, and its magnitude directly affects the dynamic and static pressure distribution, heat transfer efficiency, and the accuracy of calculations for subsequent guide vane deflection angles and fan pressure. The duct cross-sectional velocity can be obtained in various ways. For example, it can be calculated based on known cooling mass flow rate, air density, and duct cross-sectional area; alternatively, it can be obtained by directly measuring the local velocity at different locations within the duct using measuring devices such as Pitot tubes, hot-wire anemometers, or ultrasonic anemometers, and then integrating or averaging the results.

[0066] Air density ρ refers to the mass of air per unit volume. As a fundamental physical quantity in fluid dynamics calculations, air density plays a crucial role in converting mass flow rate to volumetric flow rate, calculating the kinetic energy of airflow, and determining duct resistance. Methods for obtaining air density include, but are not limited to: calculating it using the ideal gas law or a more precise real gas law based on ambient temperature, humidity, and atmospheric pressure; or, real-time measurement and estimation by installing density sensors or a combination of temperature, humidity, and pressure sensors at the duct inlet or outlet.

[0067] cross-sectional area of ​​air duct This refers to the cross-sectional area of ​​the duct perpendicular to the airflow direction. This geometric parameter is one of the key factors determining the airflow velocity within the duct and is crucial for duct design, airflow organization, and fluid dynamics calculations. The duct cross-sectional area can be obtained based on duct design drawings or through actual measurements. For some ducts with variable cross-section designs, their cross-sectional area can be dynamically changed through adjustment mechanisms (such as adjustable baffles or telescopic structures), and the current area value can be obtained in real time.

[0068] The solution in this application introduces the flow velocity of the duct cross-section. The calculation involves using the cooling mass flow rate obtained in the preceding steps. A direct link was established with the actual airflow state inside the duct. Specifically, given the known cooling mass flow rate... air density ρ and cross-sectional area of ​​the air duct In the case of using the formula The average airflow velocity within the duct can be accurately calculated. This calculation step is crucial because it transforms the abstract mass flow rate requirement into specific velocity parameters usable for fluid dynamics analysis. Obtaining the accurate duct cross-sectional velocity provides a more solid and accurate physical basis for subsequent steps, such as the dynamic adjustment of the optimal deflection angle of the guide vanes and the calculation of the target air pressure in the cooling duct. For example, the duct cross-sectional velocity directly affects the force exerted by the airflow on the guide vanes, thus influencing the determination of the optimal deflection angle; simultaneously, the velocity is also a core parameter for calculating the friction loss and local resistance of the duct, thereby determining the required target air pressure. Therefore, by introducing the calculation of the duct cross-sectional velocity, this approach effectively compensates for the shortcomings of relying solely on mass flow rate for fluid dynamics analysis, making the control and optimization of the entire cooling system more refined and accurate.

[0069] In a preferred embodiment of the present invention, the formula for calculating the optimal deflection angle of the guide vane is as follows:

[0070]

[0071] in, This indicates the optimal deflection angle of the guide vanes. This represents the maximum permissible deflection angle of the duct blades, and k represents the dimensionless empirical fitting coefficient. μ represents the hydraulic diameter of the air duct, and μ represents the aerodynamic viscosity.

[0072] In this embodiment, the optimal deflection angle of the guide vane This refers to the optimal tilt angle of the guide vanes within the air duct relative to the airflow direction. Its function is to optimize airflow organization within the duct by altering the airflow direction and flow field distribution, reducing flow resistance, improving heat exchange efficiency, and influencing the fan's operating efficiency. This angle can be precisely controlled by a servo motor driving a linkage mechanism or a stepper motor in conjunction with gear transmission to achieve precise vane rotation control.

[0073] The calculation formula provides a quantitative and precise method for determining the optimal deflection angle of guide vanes, describing complex fluid dynamics phenomena through a mathematical model, thereby achieving automated and intelligent control. This formula can be programmed into the microprocessor of the control unit, performing calculations by acquiring input parameters in real time, or by rapidly calculating using a pre-established lookup table or fitted curve based on the formula.

[0074] The maximum allowable deflection angle of the air duct blades This refers to the maximum deflection angle that the airflow blades can achieve under the constraints of structural design and fluid dynamics. As an upper limit parameter in the calculation formula, it ensures that the calculation results are within the physically achievable range, avoiding airflow separation, a sharp increase in drag, or mechanical interference due to excessive deflection. This maximum deflection angle can be determined by the mechanical structural design of the duct and blades, for example, through setting a limiting mechanism, or through experimental testing or computational fluid dynamics (CFD) simulation.

[0075] The dimensionless empirical fitting coefficients This is a dimensionless constant obtained through fitting experimental data or numerical simulations. It is used to adjust the formula's output to better match actual operating conditions. It reflects the influence of specific duct and blade geometry on airflow deflection characteristics, making the formula more universal and accurate. This coefficient can be obtained by conducting wind tunnel experiments at different wind speeds and blade deflection angles, measuring airflow characteristics, and fitting the data, or by using computational fluid dynamics (CFD) software to simulate and analyze the duct and extract data for fitting.

[0076] The hydraulic diameter of the air duct An equivalent diameter used to describe the fluid flow characteristics of non-circular pipes is defined as four times the flow area divided by the wetted perimeter. In fluid mechanics calculations, it simplifies the calculation by treating non-circular ducts as equivalent to circular pipes and is a key input for calculating dimensionless parameters such as the Reynolds number. This diameter can be calculated directly from the geometry of the duct, or for ducts with complex shapes, geometric parameters can be extracted from a CAD model for calculation.

[0077] Aerodynamic viscosity μ is a physical quantity that measures the air's resistance to shear deformation, reflecting the internal friction of airflow. In fluid dynamics calculations, especially Reynolds number calculations, it is a crucial parameter characterizing fluid properties, influencing the laminar or turbulent flow state and drag characteristics. This viscosity can be obtained by consulting standard aerodynamic handbooks based on ambient temperature and pressure, or by measuring ambient temperature and pressure in real time using sensors and then calculating it using a preset functional relationship.

[0078] The solution in this application introduces a calculation formula for the optimal deflection angle of the guide vanes, thus closely linking the cooling mass flow rate and duct cross-sectional velocity calculated in the preceding steps with the dynamic adjustment of the guide vanes. The optimal deflection angle of the guide vanes is accurately determined through this calculation formula. The exponential term in this formula essentially reflects the Reynolds number effect of the airflow, allowing the calculated optimal deflection angle to be dynamically adjusted according to the actual airflow velocity. For example, when the flow velocity in the duct section is high, the guide vanes may require a larger deflection angle to effectively guide the airflow and reduce resistance; while at lower flow velocities, a smaller deflection angle may be needed to maintain a stable flow field. In this way, the guide vanes can always be positioned to optimize airflow distribution, minimize flow resistance, and maximize heat exchange efficiency. This precise calculation and dynamic adjustment based on real-time flow velocity makes the airflow organization within the duct more rational, avoiding airflow separation and unnecessary turbulence. This significantly reduces the power consumption required for the fan to overcome resistance and decreases aerodynamic noise while meeting heat dissipation requirements. This complements the aforementioned technical concept of dynamically adjusting the guide vane deflection angle, together achieving a balance between heat dissipation efficiency, energy consumption, and noise.

[0079] In a preferred embodiment of the present invention, the formula for calculating the target air pressure of the heat dissipation duct is as follows:

[0080]

[0081] in, The target air pressure required for the heat dissipation duct is represented by λ, and the friction factor of the duct is represented by λ. Indicates the length of the air duct. This represents the local resistance coefficient of the duct foundation. This represents the deflection protection constant.

[0082] In this embodiment, the target air pressure required for the heat dissipation air duct This refers to the total pressure difference that a fan needs to provide to allow cooling air to pass through the entire heat dissipation duct system at the required mass flow rate. It represents the energy required to overcome all flow resistances within the duct (including friction loss and local resistance). This air pressure is a key parameter for fan selection and operation control, directly affecting the fan's power consumption and the performance of the heat dissipation system. Its determination is typically based on fluid mechanics principles, obtained through quantifying various resistance losses within the duct.

[0083] The friction factor λ in a duct is a dimensionless parameter used to quantify the energy loss caused by friction between the fluid and the pipe wall, as well as the viscosity of the fluid itself, when a fluid flows within a straight section of the duct. This factor is typically related to factors such as the Reynolds number and the roughness of the duct wall. Its value can be obtained by consulting standard fluid mechanics handbooks, conducting experimental measurements, or using computational fluid dynamics (CFD) simulations. For example, for a smooth circular pipe, λ can be determined using Prandtl's formula or the Nikuradse diagram; for non-circular ducts, the equivalent diameter method is often used for calculation.

[0084] duct length This refers to the total effective length of the cooling airflow duct. It directly affects the frictional resistance; the longer the duct, the larger the contact area between the fluid and the wall, and the greater the frictional loss. This length is a geometric parameter used in duct design and can be obtained through actual measurement or design drawings. (Dualisting hydraulic diameter) This is an equivalent diameter used to describe the fluid flow characteristics of non-circular ducts, transforming the calculation of flow resistance in non-circular ducts into that of circular ducts. It is defined as four times the duct's cross-sectional area divided by its wetted perimeter. For example, for a rectangular duct, the hydraulic diameter is 2ab / (a+b), where a and b are the side lengths of the duct. For a circular duct, the hydraulic diameter is its physical diameter.

[0085] Local resistance coefficient of duct foundation This is a dimensionless parameter used to quantify the energy loss caused by changes in flow direction, cross-sectional changes, or eddy currents when fluid flows through local components such as elbows, reducers, valves, and guide vanes in a duct. This coefficient reflects the degree to which a specific local component impedes fluid flow. Its value is usually obtained through experimental determination or by consulting engineering manuals; for example, the local resistance coefficient is predetermined for a specific elbow or grille.

[0086] Deflection protection constant It is a small positive value, and its function is to prevent the deflection angle of the guide vanes from being too large. When the constant is close to or equal to zero, the denominator in the calculation formula will be zero or approach zero, thus preventing the calculation result from tending to infinity or becoming unstable. This constant ensures the numerical stability of the calculation and provides a certain degree of fault tolerance to the system. Its value is usually set according to the actual application scenario and the accuracy requirements of the numerical calculation. For example, it can be a very small positive number, such as 0.001 or 0.01 radians.

[0087] This application's solution achieves refined control of fan operation by accurately calculating the target air pressure required for the cooling duct. Specifically, based on determining the cooling mass flow rate, duct cross-sectional velocity, and optimal deflection angle of the guide vanes, this solution further considers the complex resistance characteristics of fluid flow within the duct. The calculation of the target air pressure integrates both friction resistance and local resistance. Friction resistance is mainly caused by the duct length, hydraulic diameter, and fluid viscosity, and is quantified using the duct friction resistance coefficient λ. Local resistance is mainly caused by components within the duct (such as guide vanes) and is quantified using the duct foundation local resistance coefficient. Characterization was performed. It is worth noting the deflection angle of the guide vanes. The deflection effect has a significant impact on local drag. This scheme dynamically reflects the regulating effect of blade deflection on duct drag by incorporating it into the denominator of the local drag term. Deflection protection constant. The introduction of this method ensures the numerical stability of the calculation process even when the deflection angle of the guide vanes is extremely small. In this way, the system can accurately predict the wind pressure required to overcome the duct resistance based on the real-time operating status and the actual deflection of the guide vanes, thereby providing precise input for subsequent fan speed control. This ensures that the fan operates in the most economical and efficient manner, meeting heat dissipation requirements while avoiding unnecessary energy consumption and noise.

[0088] In a preferred embodiment of the present invention, the formula for calculating the optimal rotational angular velocity of the fan is as follows:

[0089]

[0090] in, This indicates the optimal rotational angular velocity of the fan. Indicates the radius of the wind turbine impeller. This represents the dimensionless total pressure coefficient of the fan. This represents the dimensionless flow coefficient of the fan.

[0091] In this embodiment, the optimal rotational angular velocity of the fan in the formula is... This refers to the ideal rotational speed at which a fan achieves the best balance between energy consumption and noise while meeting specific heat dissipation requirements (i.e., providing the required cooling mass flow rate and overcoming the target wind pressure). It is a dynamically calculated value used to guide the actual operation of the fan. (Fan impeller radius) This refers to the physical dimensional parameters of the fan impeller, usually fixed values, representing the effective radius of the fan's work radius. Its size directly affects the fan's aerodynamic performance and power consumption. (The text also mentions the dimensionless total pressure coefficient of the fan.) This is an important parameter characterizing the aerodynamic performance of a fan, reflecting its ability to generate total pressure under specific operating conditions. This coefficient is typically obtained from performance curves or experimental data provided by the fan manufacturer, and it is closely related to factors such as the fan's design and blade shape.

[0092] dimensionless flow coefficient of the fan This is another important parameter characterizing the aerodynamic performance of a fan, reflecting its ability to transport fluid flow under specific operating conditions. Similar to the dimensionless total pressure coefficient, this coefficient is also obtained from performance curves or experimental data provided by the fan manufacturer, and it is closely related to the fan's structure and operating characteristics.

[0093] The solution in this application introduces the dimensionless total pressure coefficient of the fan. and dimensionless flow coefficient Combined with the radius of the wind turbine impeller The target air pressure required for the heat dissipation duct calculated above. and cooling mass flow rate It is converted into the optimal rotational angular velocity of the wind turbine through specific mathematical relationships. This calculation formula comprehensively considers the dual requirements of the fan generating the necessary head to overcome duct resistance and the required flow rate to remove heat. Specifically, the first term in the formula... The first item primarily reflects the contribution of the fan's rotational speed required to overcome the target wind pressure, while the second item... This primarily reflects the rotational speed contribution required by the fan to provide the cooling mass flow rate. By performing a square root operation on the sum of the squares of these two contributions, a comprehensive optimal rotational angular velocity can be obtained. This velocity not only meets the heat dissipation performance requirements but also achieves an optimized balance between work efficiency and operating noise within the limits allowed by the fan's aerodynamic characteristics. This conversion mechanism allows the control system to precisely instruct the fan to operate at the most suitable speed, avoiding additional noise and energy consumption caused by excessively high speeds, and also avoiding insufficient heat dissipation caused by excessively low speeds.

[0094] In a preferred embodiment of the present invention, the formula for calculating the phase offset of the active noise cancellation compensation signal is as follows:

[0095]

[0096] in, This represents the phase offset of the noise-canceling signal. The value of is determined by adding or subtracting integer multiples of 2π from the original calculated value to make it fall within the interval [0, 2π); Z represents the number of wind turbine blades. This indicates the distance from the secondary sound source to the noise-canceling microphone. This indicates the distance from the primary sound source to the noise-canceling microphone. Indicates the speed of ambient sound.

[0097] In this embodiment, the phase offset of the noise reduction signal In an active noise control system, phase offset refers to the phase difference between the sound waves emitted by the secondary sound source (i.e., the acoustic device used to generate noise cancellation) and the sound waves emitted by the primary sound source (i.e., the noise generated by the fan) at a specific monitoring point in order to achieve destructive interference of sound waves. This phase offset is a key parameter to ensure effective noise cancellation, and its value is usually limited to the interval [0, 2π) to simplify the control logic and ensure the uniqueness of the phase relationship.

[0098] Number of wind turbine blades This refers to the total number of fixed blades on the wind turbine impeller. This parameter directly determines the fundamental frequency of the main discrete frequency noise generated by the wind turbine during rotation, because each blade periodically cuts the airflow during rotation, thereby generating sound waves.

[0099] Distance from secondary sound source to noise-canceling microphone This refers to the physical distance between the acoustic device used to generate noise cancellation (secondary sound source) and the noise-canceling microphone used to monitor noise levels and for feedback control. This distance affects the time required for sound waves emitted from the secondary sound source to reach the noise-canceling microphone, and thus affects phase calculations.

[0100] Distance from primary sound source to noise-canceling microphone This refers to the physical distance between the fan (primary sound source) and the noise-canceling microphone. This distance affects the time required for the noise generated by the fan to reach the noise-canceling microphone and is a key parameter for calculating the phase of the sound wave from the primary sound source.

[0101] Ambient sound speed The speed of sound refers to the speed at which sound waves propagate in the current environmental medium (usually air). Sound speed is affected by factors such as ambient temperature and humidity, and is a fundamental physical quantity for calculating sound wave propagation time and thus determining phase shift.

[0102] The solution in this application precisely calculates the phase shift of the active noise cancellation compensation signal. This effectively counteracts low-frequency noise within the cooling duct. Specifically, the calculation utilizes the optimal rotational angular velocity of the fan. (This parameter has been optimized in previous steps based on heat dissipation requirements and airflow characteristics.) Combined with the number of fan blades Z, the main noise frequency generated by the fan can be determined. Subsequently, by considering the distance from the primary sound source (fan) to the noise-canceling microphone... and the distance from the secondary sound source (acoustic device) to the noise-canceling microphone and ambient sound speed The propagation time difference between the primary noise and the secondary compensation sound wave at the noise-canceling microphone is precisely calculated, and the phase offset required to achieve destructive interference is derived. The π in the formula ensures the phase inversion effect, while the modulus operation normalizes the phase value to the [0, 2π) range. This precise phase calculation based on the wind turbine operating parameters and acoustic propagation path enables the active noise cancellation system to specifically generate sound waves with the same frequency, similar amplitude, and opposite phase to the wind turbine noise, thereby achieving effective low-frequency noise cancellation within the duct and significantly reducing the operating noise of the charging pile.

[0103] In a preferred embodiment of the present invention, the formula for calculating the sound pressure amplitude of the active noise cancellation compensation signal is as follows:

[0104]

[0105] in, This indicates the sound pressure level compensated by the noise reduction signal. This represents the acoustic proportional gain coefficient.

[0106] In this embodiment, the calculation formula is a mathematical model used to quantify the energy intensity required to generate antiphase sound waves. Based on the fan's operating parameters and ambient acoustic conditions, it aims to precisely match the sound pressure amplitude of the noise to be eliminated, thereby ensuring that the intensity of the active noise cancellation compensation signal matches the noise intensity generated by the fan, achieving maximum noise cancellation. The target value for the output sound wave intensity of the acoustic device is ensured to be equal to the amplitude of the noise to be eliminated, thus achieving effective cancellation. This can be achieved by driving acoustic devices such as loudspeakers with a power amplifier, based on the calculated... This can be achieved by adjusting the output power; or by using a feedback control mechanism, which monitors residual noise in the duct in real time via a microphone and fine-tunes the output power based on the monitoring results. To adapt to dynamically changing noise environments. It is a dimensionless empirical coefficient used to adjust the calculated sound pressure amplitude to compensate for energy loss, sensor or actuator nonlinearity, and the complexity of the acoustic environment in the actual system. This can be determined through experimental testing and system calibration. For example, under different fan speeds and environmental conditions, the noise amplitude generated by the fan and the amplitude of the compensation signal output by the acoustic equipment are measured, and the optimal value is determined through regression analysis or iterative optimization. . It can be a fixed value, or it can be a lookup table or function that is dynamically adjusted based on parameters such as fan speed and ambient temperature.

[0107] This application's solution uses the optimal rotational angular velocity of the fan as the core parameter, combined with physical quantities such as air density, fan impeller radius, and ambient sound velocity, to calculate the required sound pressure amplitude for the active noise cancellation compensation signal using a specific mathematical model. This calculation formula directly reflects the strong correlation between fan speed and its generated sound power, with the cube term of the optimal fan rotational angular velocity particularly highlighting the sensitive dependence of sound power on speed. By introducing an acoustic proportional gain coefficient, the theoretical calculation results are calibrated to adapt to the complexity of the actual acoustic environment and system nonlinearity. When this precisely calculated sound pressure amplitude is combined with the aforementioned determined phase information, the acoustic device can generate a compensation sound wave that is out of phase and equal in amplitude to the low-frequency noise within the cooling duct. These two signals are spatially superimposed, and through the principle of sound wave interference, effectively cancel the original noise, thereby significantly reducing the overall noise level within the duct. This collaborative mechanism, based on the precise prediction and control of the compensation signal amplitude and phase according to the fan's operating state, ensures that the active noise cancellation system can dynamically and efficiently adapt to changes in fan operating conditions, achieving a continuous silent heat dissipation effect.

[0108] A silent air duct heat dissipation device for charging piles includes:

[0109] The control unit is used to acquire the real-time operating status of the charging module and the environmental thermodynamic conditions, and output cooling mass flow rate demand signal, guide vane deflection control signal, fan speed control signal and active noise cancellation compensation signal.

[0110] The air duct body is located on the heat dissipation path of the charging module, and the air duct body is provided with rotatable guide vanes.

[0111] The drive mechanism is connected to the guide vane and receives the deflection control signal of the guide vane to adjust the deflection angle of the guide vane;

[0112] A fan is installed at the air inlet or air outlet of the air duct body and receives the fan speed control signal to adjust the rotational angular velocity.

[0113] An acoustic noise reduction unit is located near the air duct body and receives the active noise cancellation compensation signal to generate an anti-phase sound wave to cancel low-frequency noise.

[0114] The control unit is communicatively connected to the drive mechanism, the fan, and the acoustic noise reduction unit, respectively.

[0115] The core innovation of this embodiment lies in combining dynamically adjusted guide vane deflection angle with active noise cancellation technology, thereby solving the problems of uneven airflow distribution and noise spectrum shift caused by fixed duct structures, achieving a significant reduction in low-frequency noise while maintaining efficient heat dissipation. Specifically, in the prior art, the guide vane angle is fixed once during production and assembly, which cannot adapt to Reynolds number fluctuations caused by changes in fan speed, resulting in a sharp increase in local duct resistance. In contrast, the duct body of this application dynamically adjusts the deflection angle of the guide vanes in real time through a drive mechanism in response to the guide vane deflection control signal output by the control unit, maintaining the airflow in an optimal wall-attached state and effectively reducing duct resistance along the path and in local areas. At the same time, addressing the shortcomings of existing passive sound absorption measures in adapting to noise spectrum shifts, the acoustic noise reduction unit of this application actively generates sound waves that are inversely phase to the fan noise based on the active noise cancellation compensation signal generated by the control unit, accurately canceling low-frequency noise components in the heat dissipation duct.

[0116] Specifically, when the charging module is under low load, the control unit reduces the fan speed and increases the deflection angle of the guide vanes to reduce airflow separation losses. Simultaneously, the acoustic noise reduction unit generates a precise compensation signal for the low-frequency noise spectrum. Under high load, as the fan speed increases, the control unit adjusts the deflection angle of the guide vanes in real time to maintain airflow adherence to the wall and simultaneously updates the active noise cancellation compensation signal to adapt to the noise spectrum shift. For example, in a scenario where the charging module output power is 100kW and the ambient temperature is 30℃, the control unit calculates the required cooling mass flow rate as 0.5kg / s. The drive mechanism adjusts the guide vanes to a 30-degree deflection angle to optimize airflow distribution. The fan operates at a rotational speed of 1500RPM, and the acoustic noise reduction unit generates a compensation signal with a phase shift of π based on the number of fan blades and the fan speed, effectively canceling low-frequency noise in the 200Hz band.

[0117] The above description is only a preferred embodiment of the present invention and is 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 protection scope of the present invention.

Claims

1. A method for heat dissipation through a silent air duct in a charging pile, characterized in that, Includes the following steps: S1. Obtain the current real-time operating status of the charging module and the environmental thermodynamic conditions, and calculate the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise. S2. Based on the cooling mass flow rate and the geometric fluid dynamics characteristics of the air duct, dynamically adjust the optimal deflection angle of the guide vanes in the air duct, and calculate the target air pressure required to overcome the resistance along the air duct and local resistance. S3. Combining the aerodynamic characteristics of the impeller, the target wind pressure and cooling mass flow rate are converted into the optimal control command for the fan speed, and the optimal rotational angular velocity of the fan that balances work and noise is calculated. S4. Extract acoustic features based on the optimal rotational angular velocity of the fan, and generate the phase and amplitude of the active noise cancellation compensation signal in reverse based on the aeroacoustic radiation model to drive the acoustic device to cancel the low-frequency noise in the heat dissipation duct.

2. The method according to claim 1, characterized in that, In step S1, the specific method for calculating the cooling mass flow rate required to eliminate excess heat and maintain the target temperature rise is as follows: First, calculate the difference obtained by multiplying by one and subtracting the power conversion efficiency by the real-time active power of the charging module to obtain the total heat generation power of the charging module; then calculate the difference obtained by subtracting the ambient temperature from the current temperature of the charging module and divide it by the thermal resistance of the module to obtain the natural heat dissipation power; subtract the natural heat dissipation power from the total heat generation power to obtain the forced heat dissipation power required. The target temperature rise limit is then calculated by subtracting the temperature protection constant to obtain the effective allowable temperature rise. The specific heat capacity of the air at constant pressure is multiplied by this effective allowable temperature rise to obtain the heat capacity of the cooling medium. The required forced heat dissipation power is divided by the heat capacity of the cooling medium, and the quotient is used as the cooling mass flow rate.

3. The method according to claim 2, characterized in that, The flow velocity of the duct section is calculated by dividing the cooling mass flow rate by the product of the air density and the duct cross-sectional area, and the quotient is taken as the flow velocity of the duct section.

4. The method according to claim 3, characterized in that, The optimal deflection angle of the guide vane is calculated as follows: First, calculate the air density multiplied by the flow velocity of the duct section, then multiply by the hydraulic diameter of the duct, and then divide by the aerodynamic viscosity to obtain the Reynolds number; then, take the negative value of the Reynolds number and multiply it by the dimensionless empirical fitting coefficient, use this product as the exponent and the natural constant e as the base to calculate the exponential function value, subtract the exponential function value from 1, and then multiply it by the maximum allowable deflection angle of the duct vane. The resulting product is the optimal deflection angle of the guide vane.

5. The method according to claim 3, characterized in that, The target air pressure of the heat dissipation duct is calculated as follows: First, calculate the friction coefficient of the duct, multiply it by the duct length, and then divide it by the hydraulic diameter of the duct to obtain the friction coefficient. Then, calculate the local resistance coefficient of the duct foundation, divide it by the sine of the optimal deflection angle of the guide vanes, and add the deflection protection constant to obtain the sum. The quotient is the local resistance. Add the friction coefficient and the local resistance, and then multiply it by the product of half the air density and the square of the flow velocity in the duct section. The result is the target air pressure required for the heat dissipation duct.

6. The method according to claim 5, characterized in that, The optimal rotational angular velocity of the wind turbine is calculated as follows: First, calculate the quotient of the target wind pressure divided by the air density, the square of the fan impeller radius, and the dimensionless total pressure coefficient to obtain the first square term; then calculate the quotient of the cooling mass flow rate divided by the air density, the cube of the fan impeller radius, and the dimensionless flow coefficient, and square this quotient to obtain the second square term; add the first square term and the second square term and take the square root, and the result is taken as the optimal rotational angular velocity of the fan.

7. The method according to claim 5, characterized in that, The phase offset of the active noise cancellation compensation signal is calculated as follows: First, calculate the optimal rotational angular velocity of the wind turbine, multiply it by the number of wind turbine blades, then multiply it by the distance from the secondary sound source to the noise-canceling microphone, and then divide it by the ambient sound speed to obtain the first phase delay term. Next, calculate the optimal rotational angular velocity of the wind turbine, multiply it by the number of wind turbine blades, then multiply it by the distance from the primary sound source to the noise-canceling microphone, and then divide it by the ambient sound speed to obtain the second phase delay term. Add the first phase delay term to pi and subtract the second phase delay term to obtain the original phase value. Then, add or subtract an integer multiple of pi to this original phase value to make it fall within the range of zero to twice pi, which is used as the phase offset of the noise-canceling signal.

8. The method according to claim 6, characterized in that, The sound pressure amplitude of the active noise cancellation compensation signal is calculated as follows: First, take the cube of the optimal rotational angular velocity of the fan, then multiply it by the cube of the fan impeller radius, and then multiply it by the air density to obtain the numerator. Divide the numerator by the ambient sound speed to obtain the basic sound pressure amplitude. Then multiply this basic sound pressure amplitude by the acoustic proportional gain coefficient to obtain the compensated sound pressure amplitude of the noise-cancelling signal.

9. A silent air duct heat dissipation device for a charging pile, applied to the method described in any one of claims 1 to 8, characterized in that, include: The control unit is used to acquire the real-time operating status of the charging module and the environmental thermodynamic conditions, and output cooling mass flow rate demand signal, guide vane deflection control signal, fan speed control signal and active noise cancellation compensation signal. The air duct body is located on the heat dissipation path of the charging module, and the air duct body is provided with rotatable guide vanes. A drive mechanism is connected to the guide vane for transmission and receives the guide vane deflection control signal to adjust the deflection angle of the guide vane; A fan is installed at the air inlet or air outlet of the air duct body and receives the fan speed control signal to adjust the rotational angular velocity. An acoustic noise reduction unit is located near the air duct body and receives the active noise cancellation compensation signal to generate an anti-phase sound wave to cancel low-frequency noise. The control unit is communicatively connected to the drive mechanism, the fan, and the acoustic noise reduction unit.

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