A multi-grade wind speed test system of a hand-held digital screen air pump and a method thereof

Abstract

The application discloses a multi-gear wind speed test system of a handheld digital display screen air pump and a method thereof, and relates to the technical field of fluid power equipment test and control. The system comprises a main control unit, a power supply module, a motor driving module, an air pump assembly and a digital display screen. The main control unit collects real-time bus voltage and operating current signals, extracts current ripple frequency, and uses the coupling relationship between voltage and frequency to calculate aerodynamic load and match wind speed. The system combines battery internal resistance compensation, temperature rise monitoring and inertial measurement unit filtering to correct errors caused by voltage drop, airflow obstruction and equipment jitter. The modulated light signal generated by the digital display screen can be used for non-contact precision calibration. The application does not require external sensors, and realizes high-precision wind speed measurement and closed-loop control.

Description

Technical Field

[0001] This invention relates to the field of fluid power equipment testing and control technology, and in particular to a multi-speed in-situ testing system for a portable, battery-powered handheld digital display air pump and its implementation method. Background Technology

[0002] Handheld air pumps, especially high-speed fans with integrated digital displays, have seen widespread adoption in recent years due to their portability and high performance in applications such as outdoor inflation, electronic device cleaning, and rapid cooling. These devices typically feature multiple fan speed settings to meet the needs of different applications. As a core performance indicator, the accuracy and consistency of fan speed are crucial for user experience and product quality control.

[0003] Traditional wind speed testing methods typically rely on external precision measuring instruments, such as hot-wire anemometers or impeller anemometers. On the production line, the air pump under test needs to be placed in a standardized test duct, and these external sensors directly measure the airflow at the outlet of the device under test. While this method offers high accuracy, it has several significant limitations. First, the testing equipment is expensive and complex to maintain, increasing production costs. Second, the testing process requires precise alignment and sealing of the air pump and the testing equipment, making operation cumbersome, inefficient, and unsuitable for large-scale automated production. Furthermore, for handheld devices, the actual usage scenario is dynamically changing; traditional fixed testing methods cannot simulate the changes in user posture and environmental airflow disturbances during handheld use, potentially leading to discrepancies between test results and actual user experience.

[0004] To simplify testing procedures, some existing technologies attempt to integrate miniaturized flow rate sensors, such as flow sensors based on microelectromechanical systems (MEMS), into the air pump. However, integrating such sensors into the compact internal space of a handheld air pump not only alters the original flow channel structure and affects the pump's aerodynamic performance, but also exposes the precision sensors to dust and impurities in the high-speed airflow, leading to contamination and damage, decreased measurement accuracy, and shortened lifespan. Furthermore, integrating additional sensors also increases hardware costs and system complexity.

[0005] In recent years, with the development of motor control technology, sensorless control technology has been gradually applied to the estimation of motor speed. By analyzing the back electromotive force or current signal of the motor, the motor speed can be inferred to a certain extent. In fan applications, there is a certain correlation between motor speed and wind speed. Therefore, some studies have attempted to indirectly estimate wind speed by estimating motor speed. However, this method faces serious challenges in applications such as handheld digital display air pumps. First, handheld air pumps typically use high-power-density brushless DC motors (BLDC) or permanent magnet synchronous motors (PMSM), which operate at extremely high speeds and have a wide range of load variations. Traditional speed estimation methods based on back electromotive force have poor accuracy under high-speed and light-load conditions. Second, handheld air pumps are usually battery-powered, and the battery voltage fluctuates with power consumption and load changes. This voltage fluctuation directly affects the motor's operating characteristics, making the relationship between speed and wind speed complex and nonlinear. Especially when adjusting multiple speeds, the voltage drop varies at different speeds, further exacerbating the difficulty of accurate estimation. Furthermore, the pneumatic load of an air pump is not only related to wind speed, but is also affected by various factors such as airflow conditions at the inlet and outlet, air density, temperature, and the user's hand posture. Existing sensorless technologies often only provide a rough estimate of the rotational speed, making it difficult to accurately reflect the actual pneumatic load and output wind speed.

[0006] Furthermore, in product quality control and after-sales service, a rapid, non-invasive method is needed to verify the air pump's wind speed calibration accuracy. Existing methods typically require disassembling the equipment or connecting dedicated debugging interfaces, which is inconvenient and can easily damage the equipment.

[0007] In summary, existing handheld digital display methods for testing air pump wind speed suffer from high cost, low efficiency, difficulty adapting to the characteristics of portable devices, and inability to achieve rapid, non-invasive calibration and verification. Therefore, there is an urgent need for an innovative wind speed testing system and method that can accurately measure and dynamically display multiple wind speed levels, and facilitate convenient calibration and verification, without relying on external precision instruments or internally integrated flow sensors, by utilizing the air pump's own electrical signal characteristics. This would improve product performance, reduce production costs, and optimize user experience. Summary of the Invention

[0008] The purpose of this invention is to provide a multi-speed testing system and method for a handheld digital display air pump, which aims to solve the problems in the background art.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application discloses a multi-speed wind speed testing system for a handheld digital display air pump, comprising: Main control unit, power supply module, motor drive module, air pump assembly, and digital display screen; The main control unit is configured to perform a wind speed test mode, which includes the following steps: The real-time bus voltage value of the power supply module and the real-time operating current signal of the motor drive module are collected. Frequency domain analysis processing is performed on the real-time operating current signal to extract the commutation ripple frequency component that is positively correlated with the motor speed; The multi-dimensional mapping data structure pre-stored in the main control unit is invoked, and the real-time bus voltage value and the commutation ripple frequency component are used as dual index coordinates to retrieve and interpolate the corresponding theoretical aerodynamic load value or direct wind speed value. The digital display screen is electrically connected to the main control unit and is used to dynamically display the current wind speed test results.

[0010] Optionally, the power supply module includes a battery management system; The main control unit is configured to obtain battery state-of-charge parameters and battery internal resistance parameters from the battery management system. When calculating the theoretical aerodynamic load value, the main control unit applies a compensation coefficient based on the battery internal resistance parameter to correct the deviation of the operating current signal caused by the voltage drop of the power supply module.

[0011] Optionally, the main control unit includes a thermal monitoring interface connected to a temperature sensor located on the discharge circuit of the power supply module; The main control unit calculates the temperature rise rate of the power supply module within a preset test cycle; When the temperature rise rate exceeds the safety threshold corresponding to the currently selected gear, the main control unit determines that the airflow is obstructed and generates a zero wind speed or error correction signal.

[0012] Optionally, the motor drive module includes a pulse width modulation controller; The main control unit dynamically adjusts the duty cycle of the pulse width modulation controller based on the difference between the theoretical aerodynamic load value and the target wind speed value at the current gear, thereby forming a closed-loop constant speed control. The digital display screen updates the current wind speed test results in real time to reflect the steady-state wind speed after closed-loop adjustment.

[0013] Optionally, the digital display screen is configured to perform optical encoding output function; Under the optical encoding output function, the digital display screen is configured to perform the optical encoding output function; Under the optical encoding output function, the digital display screen controls the brightness flashing sequence or color switching frequency of the display interface according to the current wind speed test result, and generates a modulated light signal containing wind speed numerical information. The modulated light signal is configured to be read and decoded non-contactly by external optical detection equipment.

[0014] Optionally, the main control unit uses a fast Fourier transform algorithm to process the real-time operating current signal to extract the ripple frequency component; The main control unit identifies the fundamental frequency related to the commutation frequency of the motor in the air pump assembly, and uses the fundamental frequency as a proxy variable for the physical rotational speed of the fan blades inside the air pump assembly.

[0015] Optionally, the preset multi-level wind speed mapping table contains multiple sets of calibration curves, each set of calibration curves corresponding to a specific range of the real-time bus voltage value. The main control unit selects a corresponding calibration curve based on the currently detected real-time bus voltage value to perform interpolation calculations on the wind speed test results.

[0016] Optionally, the system further includes an inertial measurement unit connected to the main control unit; The main control unit detects the vibration amplitude of the handheld digital display screen air pump through the inertial measurement unit; When the jitter amplitude exceeds the stability threshold, the main control unit applies a filtering algorithm to the real-time operating current signal to eliminate signal noise caused by the gyro effect on the rotor of the air pump assembly.

[0017] Optionally, the digital display screen includes a partitioned display interface, with the first partition displaying wind speed values ​​and the second partition displaying a dynamic bar graph representing the load percentage of the motor drive module; The main control unit adjusts the refresh rate of the second partition to match the sampling frequency of the wind speed test mode.

[0018] Secondly, an embodiment of the present invention provides a method for testing multiple wind speeds using the system described in the first aspect, comprising the following steps: Upon entering test mode, the main control unit acquires the real-time bus voltage of the power supply module; The air pump assembly is driven to operate at the preset initial duty cycle corresponding to the target gear. Collect real-time operating current and extract current ripple frequency; Retrieve the voltage-frequency-wind speed mapping relationship from the memory; Based on the extracted current ripple frequency and the real-time bus voltage, the compensated wind speed value is calculated in the mapping relationship. A visual output is generated on a digital display screen, the output including modulated display parameters to encode the compensated wind speed value for external optical verification.

[0019] The present invention has achieved the following beneficial effects: The present invention provides a multi-speed wind speed testing system and method for a handheld digital display air pump. Through innovative sensorless technology, it utilizes the coupling relationship between the ripple frequency component of the motor operating current and the real-time bus voltage to accurately calculate the aerodynamic load and wind speed. Compared with existing technologies, the present invention has significant advantages. First, it completely eliminates the dependence on external measuring equipment and internal flow rate sensors, greatly reducing hardware costs and system complexity, and improving product reliability and integration.

[0020] Secondly, by monitoring and compensating for bus voltage fluctuations in real time, this invention effectively solves the problem of low accuracy in wind speed estimation for handheld devices powered by batteries, ensuring the accuracy and consistency of test results under different power and load conditions.

[0021] Furthermore, the calibration and verification method based on modulated optical signals from a digital display screen proposed in this invention provides a rapid, non-contact, and low-cost quality inspection method, greatly improving production line testing efficiency and after-sales service convenience. In addition, by integrating technologies such as battery management, thermal monitoring, closed-loop control, advanced signal processing, and inertial measurement compensation, this invention constructs a comprehensive and robust wind speed testing and control system capable of adapting to the complex dynamic operating environment of handheld devices, significantly enhancing the product's intelligence level and user experience.

[0022] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a multi-speed wind speed testing system for a handheld digital display air pump according to an embodiment of the present invention; Figure 2 This is a flowchart of a multi-speed testing method for a handheld digital display air pump according to an embodiment of the present invention. Detailed Implementation

[0025] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0026] Example 1

[0027] This embodiment provides a multi-speed testing system for a handheld digital display air pump. This system aims to solve the problems in existing portable air pump wind speed measurements, such as reliance on external equipment and significant accuracy fluctuations due to power supply volatility. (Refer to...) Figure 1 The system mainly includes a main control unit, a power supply module, a motor drive module, an air pump assembly, and a digital display screen. These modules work together to achieve the function of accurately calculating wind speed through electrical signal analysis without the need for physical wind speed sensors.

[0028] The main control unit (MCU) is the core of the entire system, typically employing a microcontroller (MCU) or digital signal processor (DSP) with high-speed digital signal processing capabilities. The MCU coordinates the work of each module, executes the wind speed testing algorithm, and controls the output display. The power supply module provides a stable power supply to the system; for handheld devices, this module usually includes a rechargeable lithium battery pack and corresponding charge / discharge management circuitry. The motor drive module converts the electrical energy provided by the power supply module into alternating current signals required to drive the air pump assembly, according to the instructions from the MCU. The air pump assembly is the core component responsible for generating airflow, typically comprising a high-speed brushless DC motor and a centrifugal or axial impeller coaxially connected to it. The digital display screen visually shows the user the current operating status and wind speed test results.

[0029] The core innovation of this invention lies in the wind speed test mode executed by the main control unit. This mode utilizes the inherent coupling relationship between the electrical signal and the mechanical load during motor operation, especially the high-frequency ripple characteristics in the current signal, to infer the aerodynamic load and thus determine the wind speed.

[0030] When the system enters wind speed testing mode, the main control unit first initiates the acquisition of the real-time bus voltage value at the output of the power supply module. The bus voltage is the energy source for the motor drive, and its amplitude directly affects the motor's output power and speed characteristics. In battery-powered systems, the bus voltage is not constant; it decreases as the remaining battery power decreases and the load current increases (due to internal resistance). Therefore, real-time monitoring of the bus voltage is a prerequisite for accurately analyzing the motor's operating status. The main control unit performs high-frequency sampling of the bus voltage using its built-in analog-to-digital converter (ADC) and removes measurement noise using a digital filtering algorithm to obtain an accurate real-time bus voltage value.

[0031] Simultaneously, the main control unit synchronously acquires the real-time operating current signal of the motor drive module. This current signal reflects the energy consumption of the motor under the current operating conditions. Current signal acquisition is typically achieved by connecting a precision sampling resistor in series in the motor drive circuit or by using a Hall current sensor. The main control unit also utilizes a high-resolution ADC to sample the current signal at high speed.

[0032] The acquired real-time operating current signal contains a wealth of information. It includes not only DC and low-frequency components related to motor torque, but also high-frequency ripple components caused by motor commutation and pulse-width modulation (PWM) driving. A key technical feature of this invention is that the main control unit does not primarily rely on the current amplitude to determine the load, but rather focuses on extracting the ripple frequency component from the real-time operating current signal.

[0033] In a brushless DC motor, the current in the stator winding undergoes a step change during commutation, generating a current ripple with a specific frequency and amplitude. The frequency of this ripple is directly proportional to the motor's mechanical speed. Specifically, the fundamental frequency of the ripple is typically an integer multiple of the motor's electrical angular frequency, which in turn is related to the mechanical speed and the number of pole pairs. Therefore, by accurately measuring the frequency of the current ripple, the real-time speed of the motor can be calculated very precisely.

[0034] The main control unit performs advanced signal processing on the acquired current signal. First, the signal may need to be preprocessed using a bandpass filter to highlight commutation-related frequency components and suppress interference from other frequencies. Then, the main control unit uses spectral analysis techniques, such as Fast Fourier Transform (FFT) or Phase-Locked Loop (PLL), to accurately identify and extract the ripple frequency components in the current signal.

[0035] After obtaining the real-time bus voltage and current ripple frequency components, the main control unit begins to calculate the current theoretical aerodynamic load value. This step is crucial for wind speed estimation. There is a complex nonlinear relationship between the aerodynamic load (i.e., wind resistance) of the air pump assembly and the output wind speed and motor speed. At the same output wind speed, a larger aerodynamic load requires a larger torque output from the motor. However, at the same motor speed (i.e., the same ripple frequency), changes in the aerodynamic load will be reflected in the motor's input power and efficiency.

[0036] This invention reveals that the coupling relationship between the real-time bus voltage value and the current ripple frequency component can uniquely determine the current theoretical aerodynamic load value. Specifically, the current ripple frequency represents the actual operating speed of the motor. At a specific speed, the motor performs work on the aerodynamic load. The real-time bus voltage represents the current available input energy level. The main control unit uses a pre-established motor model or a relational model calibrated from experimental data to process these two parameters. This model describes the correspondence between motor speed (characterized by ripple frequency) and aerodynamic load under different bus voltages. For example, when the bus voltage is high, the motor can generate a large aerodynamic load at a lower speed; while when the bus voltage drops, to maintain the same aerodynamic load, the motor needs to increase its speed (if possible), or at the same speed, its aerodynamic load capacity will decrease. By comprehensively considering these two dimensions, the main control unit can accurately calculate the theoretical aerodynamic load value borne by the air pump assembly at the current moment.

[0037] The model building process is crucial to ensuring the sufficiency and feasibility of the solution. During the product development phase, extensive experimental data collection is required in a controlled environment, covering different voltage ranges and load conditions. Accurate model parameters are then fitted using system identification and parameter estimation techniques. This process ensures that even without direct measurement of the pneumatic load, the load condition can be accurately inferred from the electrical signal characteristics.

[0038] After calculating the theoretical aerodynamic load value, the next step is to convert it into a wind speed value that users can understand. Due to factors such as the air pump's flow channel structure and impeller design, there is a definite mapping relationship between the aerodynamic load and the final output wind speed. The main control unit stores a preset multi-level wind speed mapping table. This mapping table was calibrated through a large amount of experimental data during the product development phase. It records the actual output wind speed corresponding to different theoretical aerodynamic load values ​​under standard atmospheric conditions. The establishment of this mapping table also requires a precise calibration process. During the R&D phase, high-precision reference anemometers (such as laser Doppler anemometers) are used to measure the actual wind speed under different aerodynamic loads in standardized testing fixtures. By collecting sufficient data points and performing curve fitting, the mapping table is finally formed and stored in the main control unit.

[0039] In the fixed flow channel structure of a handheld air pump, the aerodynamic load (i.e., wind resistance torque) has a non-linear power function relationship with the physical rotational speed of the impeller. Theoretically, the wind speed can be inferred simply by knowing the impeller rotational speed. However, in battery-powered portable devices, the supply voltage is not constant but decreases significantly as the battery power is consumed. Fluctuations in the bus voltage directly alter the motor's torque-speed characteristic curve (TN curve). Specifically, at the same physical rotational speed, different bus voltages will change the required duty cycle and input current of the motor, meaning that relying solely on rotational speed cannot accurately pinpoint the current operating state. Therefore, this system constructs a lookup mechanism using real-time bus voltage and current ripple frequency (a proxy variable for rotational speed) as dual indexes.

[0040] To achieve the above mechanism, this invention requires a standardized wind tunnel calibration process during the research and development or production phase before the system leaves the factory, in order to generate a multi-level wind speed mapping table stored in the main control unit. The specific steps of this process are as follows: Baseline environment setup: The handheld air pump to be calibrated is fixed in a standard test wind tunnel. A high-precision laser Doppler anemometer or hot-wire anemometer is equipped at the wind tunnel outlet as a reference source for the actual wind speed.

[0041] Full voltage domain traversal: Replace the air pump's battery module with a programmable precision DC power supply. Subdivide the supply voltage from the lithium battery's full charge cutoff voltage (e.g., 4.2V / cell) to its discharge cutoff voltage (e.g., 3.0V / cell) and set multiple voltage test points (e.g., every 0.1V as a step).

[0042] Load characteristic scan: At each fixed voltage test point, the motor drive module is controlled to drive the air pump with different duty cycles, so that its speed covers the full range from stop to maximum speed.

[0043] Data anchoring and input: Under each stable operating state, the main control unit extracts the current current ripple frequency and real-time bus voltage as input coordinates (X, Y), and records the actual wind speed measured by the external anemometer as the output value (Z).

[0044] Surface Fitting and Solidification: After collecting a large number of test points, the system obtains a discrete 3D point cloud. Using interpolation algorithms (such as bilinear interpolation or spline interpolation), these discrete points are fitted into a continuous surface model, which is then converted into a digital look-up table and solidified into the non-volatile memory of the main control unit.

[0045] In actual user operation, the main control unit no longer performs complex fluid dynamics formula derivations, but instead executes efficient table lookup operations. The main control unit collects the current bus voltage and ripple frequency in real time, using them as indexes to retrieve values ​​from the aforementioned mapping table. If the measured value lies between two calibration points, the main control unit automatically performs linear interpolation to obtain a high-precision wind speed value calibrated by both voltage and rotational speed. This method avoids complex floating-point calculations and solves the nonlinear impact of battery voltage fluctuations on measurement accuracy, ensuring testing accuracy throughout the battery's entire lifespan.

[0046] The master control unit matches the calculated theoretical aerodynamic load value against the mapping table. This matching process may involve table lookups and interpolation calculations to obtain high-resolution wind speed test results. For example, if the calculated aerodynamic load value falls between two adjacent records in the mapping table, the master control unit uses linear interpolation or spline interpolation algorithms to calculate the accurate wind speed value. In this way, the master control unit generates the current wind speed test result.

[0047] Finally, the system needs to display the test results to the user. The digital display screen is electrically connected to the main control unit via a communication interface such as Serial Peripheral Interface (SPI) or I2C. The main control unit sends the generated current wind speed test results to the digital display screen for dynamic display.

[0048] This invention specifically proposes two display formats to meet different application needs. The first is a traditional numerical display, which directly displays the specific wind speed value on the screen, such as 20 meters per second. This method is intuitive and easy to understand, allowing users to easily grasp the current wind speed.

[0049] The second display format is a modulated optical signal synchronized with the wind speed test results. This is an innovative information output method, primarily used for automated testing and calibration verification. In this mode, the main control unit modulates the optical characteristics of the digital display screen, such as brightness, color, or refresh rate, according to a predetermined encoding protocol based on the wind speed test results. For example, the main control unit can control the screen to flash at a specific frequency, proportional to the measured wind speed value; or, different colors can be used to represent different wind speed ranges. This modulated optical signal can be captured and decoded by an external optical sensor, enabling the reading and verification of wind speed test results without establishing a physical electrical connection with a handheld air pump. This is of great significance for rapid quality inspection and automated calibration on the production line.

[0050] In summary, this embodiment achieves a high-precision, low-cost sensorless wind speed testing method by collecting and analyzing the bus voltage and current ripple frequency during the operation of a handheld air pump and utilizing their coupling relationship with the pneumatic load. This method overcomes the limitations of traditional testing methods, is particularly suitable for portable, battery-powered devices, and provides convenience for automated testing through an innovative modulated optical signal display method.

[0051] Example 2

[0052] This embodiment, based on Embodiment 1, further considers the impact of dynamic changes in the power supply characteristics of the battery-powered system on the accuracy of wind speed testing, and proposes a corresponding compensation mechanism. In handheld devices, the performance of the power supply module is crucial to the stability and accuracy of the entire system.

[0053] In this embodiment, the power supply module includes not only a battery pack but also an advanced battery management system (BMS). The BMS monitors the battery's status, including voltage, current, temperature, and state of charge (SOC), and provides protection against overcharge, over-discharge, and overcurrent. More importantly, the BMS can estimate the battery's internal resistance parameters in real time. The battery's internal resistance is not a constant value; it changes with battery aging, temperature variations, and different states of charge.

[0054] The main control unit exchanges data with the BMS via a communication interface (such as SMBus or UART) to obtain the battery's state of charge (SOC) and internal resistance parameters in real time. SOC reflects the remaining battery capacity, while internal resistance is a key factor affecting the power supply's output characteristics.

[0055] During the wind speed test described in Example 1, when the air pump assembly is running, especially at high wind speed settings, the motor draws a large current from the power supply module. According to Ohm's law, when current flows through the battery's internal resistance, a voltage drop occurs across that resistance, causing the actual bus voltage output by the power supply module to be lower than the battery's open-circuit voltage. This phenomenon is called voltage sag.

[0056] Voltage dips directly affect the operating current signal of the motor drive module. On the one hand, a decrease in bus voltage reduces the motor's output power at the same duty cycle, potentially leading to a decrease in speed. On the other hand, to maintain the desired speed or power, the motor drive module may need to increase the current. This deviation in the operating current signal caused by voltage dips, if left uncorrected, will affect the accuracy of subsequent calculations of theoretical aerodynamic load values.

[0057] To address this issue, this embodiment introduces a compensation mechanism based on battery internal resistance parameters when calculating the theoretical aerodynamic load value. The main control unit applies a corresponding compensation coefficient based on the real-time battery internal resistance parameters obtained from the BMS. This compensation coefficient, pre-calibrated experimentally or calculated based on an electrochemical model, describes the degree of influence of voltage drop on the current signal under different internal resistance values ​​and load currents.

[0058] The specific compensation process is as follows: The main control unit first estimates the actual voltage drop value based on the current operating current signal and internal resistance parameters. Then, it uses this voltage drop value and a compensation coefficient to correct the acquired operating current signal. For example, if the voltage drop causes the amplitude of the current signal to be too low, the compensation coefficient will be used to adjust the effective value of the current signal upward; if the voltage drop causes the waveform of the current signal to be distorted, the compensation coefficient may be used to adjust the phase or frequency characteristics of the current signal.

[0059] Another approach is for the main control unit to add the estimated voltage drop to the actual measured bus voltage value to obtain an equivalent open-circuit voltage value. When solving the theoretical aerodynamic load, this equivalent open-circuit voltage value is used instead of the actual bus voltage value and input into the coupling model.

[0060] To establish an accurate compensation model or coefficient table, extensive experimental testing is required during the research and development phase. Experiments need to use batteries with different aging levels, temperatures, and states of charge to measure the changes in internal resistance, voltage drop, and operating current signals under various load conditions. By analyzing and fitting the experimental data, a universally applicable compensation model can be obtained.

[0061] In this way, the main control unit can effectively eliminate current signal deviations caused by voltage drops in the power supply module, making the calculated theoretical aerodynamic load values ​​closer to reality. This is crucial for ensuring the accuracy and consistency of wind speed test results throughout the battery's entire lifespan and under different temperature and charge conditions. For example, even if battery aging leads to increased internal resistance, the system can still provide reliable wind speed readings through real-time compensation, thereby improving product robustness and user experience.

[0062] Furthermore, regarding battery internal resistance compensation, this invention does not simply correct the final wind speed result with a coefficient, but instead employs a virtual terminal voltage reconstruction technique that is more in line with physical principles. Its core lies in restoring the battery's electromotive force capability under ideal no-load conditions, thereby eliminating the impact of voltage drops on table lookup accuracy.

[0063] The specific implementation logic is as follows: The main control unit reads the current dynamic internal resistance parameter from the battery management system (BMS) in real time through the communication interface. This parameter is estimated by the BMS in real time based on the battery's current temperature, state of aging (SOH), and state of charge (SOC), and therefore reflects the battery's true physical state better than a fixed internal resistance constant.

[0064] At the moment the wind speed test is conducted, the main control unit simultaneously collects the real-time total current flowing through the battery. The main control unit performs logical operations internally, multiplying the real-time total current by the dynamic internal resistance parameter to calculate the virtual voltage drop value lost due to the battery's internal resistance at the current moment.

[0065] Subsequently, the main control unit sums the measured real-time bus voltage value with the virtual voltage drop value. This summation result is defined as the reconstructed open-circuit voltage. This reconstructed open-circuit voltage characterizes the theoretical maximum potential energy that the battery can provide at the current moment, eliminating voltage fluctuation interference caused by load current.

[0066] When subsequently calling the multidimensional mapping data structure, the main control unit uses the reconstructed open-circuit voltage instead of the measured bus voltage as the index coordinate for the voltage dimension. Since the mapping table is calibrated under ideal conditions with a regulated source (internal resistance close to zero), using the reconstructed open-circuit voltage for table lookup enables the system to still match the correct motor operating curve even under battery aging or high-current discharge conditions, thereby achieving precise physical compensation for voltage drops and ensuring absolute stability of wind speed readings.

[0067] Example 3

[0068] This embodiment, based on Embodiment 1, focuses on abnormal operating conditions that the handheld air pump may encounter during use, particularly airflow obstruction, and designs corresponding detection and protection mechanisms. In actual use, users may inadvertently block the air pump's inlet or outlet, or use it in a confined space, leading to poor airflow circulation. Such airflow obstruction can cause a drastic change in the air pump's pneumatic load, potentially posing a safety hazard.

[0069] When airflow is obstructed, the air pump assembly needs to overcome greater resistance to push the air, leading to an increased motor load and thus drawing a larger current. Continuous operation with high current generates significant heat in the power supply module and motor drive module, potentially causing battery overheating, damage to electronic components, or even a fire. Furthermore, under obstructed airflow conditions, the wind speed testing algorithm described in Example 1 may fail due to operating conditions exceeding its normal calibration range, resulting in displayed wind speed values ​​that are significantly inconsistent with the actual situation.

[0070] To monitor the system's thermal status in real time and identify abnormal operating conditions such as airflow obstruction, this embodiment integrates a temperature sensor into the system. Specifically, the main control unit includes a thermal monitoring interface connected to a temperature sensor located on the power supply module's discharge circuit. This temperature sensor is preferably placed in critical locations with high heat generation, such as the power MOSFET, battery protection board, or battery itself, to monitor the core temperature of the system in real time.

[0071] In wind speed test mode, the main control unit not only performs wind speed calculations but also continuously monitors the temperature sensor readings. Within a preset test cycle (e.g., 1 second or less), the main control unit calculates the temperature rise rate of the power supply module. The temperature rise rate refers to the amount of temperature change per unit time; it is more sensitive than absolute temperature in reflecting sudden changes in system heat load.

[0072] During normal operation, although the system generates heat, its rate of temperature rise remains within a reasonable range, and eventually reaches thermal equilibrium with the intervention of the cooling system. However, when airflow obstruction occurs, the system's rate of temperature rise will increase rapidly due to the sharp increase in load and the potential decrease in cooling efficiency (especially if the airflow itself also contributes to heat dissipation).

[0073] This invention establishes a corresponding safety threshold for each wind speed setting through experimental calibration and thermal simulation analysis. The normal heat generation varies at different speeds, therefore the safety thresholds should also differ. For example, the safety threshold for high wind speed settings will be higher than that for low wind speed settings.

[0074] The main control unit compares the calculated temperature rise rate with the safety threshold corresponding to the currently selected temperature setting in real time. When the monitored temperature rise rate exceeds the safety threshold, the main control unit determines that the system is in a state of obstructed airflow.

[0075] Once airflow obstruction is detected, the main control unit will immediately take appropriate measures to protect the system and alert the user. One measure is to generate a zero-speed signal, which forces the wind speed reading on the digital display to zero, possibly accompanied by flashing or warning icons, to clearly inform the user that the current airflow has been interrupted or severely restricted and is no longer a valid wind speed output state.

[0076] Another approach is to generate an error correction signal. Under slight obstruction, the system may still maintain a certain level of airflow output, but its wind speed will have significantly decreased. In this case, the main control unit can correct the original wind speed test results based on the rate of temperature rise and the degree of load change. Specifically, a thermal model can be established to estimate the increase in energy dissipation corresponding to abnormal temperature rise, and thereby determine the degree of decrease in aerodynamic efficiency. For example, an abnormal temperature rise indicates that some electrical energy has been converted into heat energy rather than kinetic energy, so this portion of energy needs to be subtracted when calculating wind speed, thus displaying a more realistic, reduced wind speed value.

[0077] By using this abnormal operating condition detection mechanism based on the rate of temperature rise, this embodiment not only improves the safety of the handheld air pump and prevents overheating damage, but also provides more accurate information feedback in abnormal situations, avoiding misleading users, thereby significantly improving the product's intelligence level and reliability.

[0078] Example 4

[0079] This embodiment, building upon Embodiment 1, further explores how to utilize wind speed test results to achieve precise control of the air pump's output wind speed, thereby improving product performance and user experience. Handheld air pumps typically offer multiple speed settings, and users expect that after selecting a certain speed setting, the air pump can output a stable and constant wind speed, unaffected by battery power fluctuations, ambient temperature changes, or slight load disturbances.

[0080] In this embodiment, the motor drive module includes a high-performance pulse width modulation (PWM) controller. The PWM controller adjusts the duty cycle of the voltage or current input to the motor windings by rapidly switching power switching transistors, thereby achieving precise control of the motor speed and power.

[0081] The wind speed testing system described in Example 1 can calculate the current theoretical aerodynamic load value in real time, which directly reflects the current actual output wind speed. This example utilizes this real-time feedback information to construct a closed-loop constant speed control system.

[0082] When a user selects a target wind speed setting, the main control unit stores the corresponding target wind speed value (and the corresponding target aerodynamic load value). The main control unit compares the calculated current theoretical aerodynamic load value with the target value in real time. This difference reflects the deviation between the actual wind speed and the desired wind speed.

[0083] Based on this difference, the main control unit dynamically adjusts the duty cycle of the PWM controller using a closed-loop control algorithm (such as a proportional-integral-derivative control algorithm, but the specific implementation is not limited to this, and can be fuzzy control or other nonlinear control strategies).

[0084] Specifically, if the calculated theoretical aerodynamic load value is lower than the target value (i.e., the actual wind speed is too low), the main control unit will increase the PWM duty cycle to increase the energy input to the motor, thereby increasing the motor speed and output wind speed until the actual wind speed approaches the target wind speed. Conversely, if the theoretical aerodynamic load value is higher than the target value (although this rarely occurs in constant speed control, it may be caused by a sudden external airflow boost), the main control unit will decrease the PWM duty cycle to reduce the motor speed in order to maintain stable wind speed.

[0085] Through this closed-loop control mechanism, the system can automatically compensate for performance drift caused by battery voltage fluctuations and motor temperature changes, as well as load changes caused by external airflow disturbances. For example, when the battery charge decreases, causing a drop in bus voltage, the closed-loop controller will automatically increase the duty cycle to maintain a constant fan speed output until the motor's maximum power output capacity is reached. This greatly improves the consistency and stability of the product during use.

[0086] Real-time wind speed measurement is crucial for implementing closed-loop control. This invention utilizes the current ripple frequency to calculate wind speed, offering advantages such as fast response and high sampling rate, making it ideal for use as a feedback signal in closed-loop control. Compared to traditional wind speed sensors, it exhibits virtually no delay, enabling it to reflect wind speed changes more promptly.

[0087] During the closed-loop adjustment process, the digital display screen serves more than just to show the target wind speed; it updates the current wind speed test results in real time to reflect the steady-state wind speed after the closed-loop adjustment. This means that the wind speed value seen by the user on the screen is the actual output wind speed that has been precisely controlled and stabilized by the system, rather than a fixed set value. This real-time and accurate feedback further enhances the user's confidence in the product's performance.

[0088] In summary, this embodiment combines sensorless wind speed testing technology with PWM closed-loop control technology to achieve a high-performance constant speed control scheme, ensuring that the handheld air pump can provide stable and accurate wind speed output under various operating conditions, significantly improving product quality and user experience.

[0089] Example 5

[0090] This embodiment, based on Embodiment 1, elaborates on the technical details of generating modulated optical signals using a digital display screen and expands its application in product calibration and quality verification. This technology aims to provide a non-contact, efficient, and low-cost method to verify the wind speed testing accuracy of handheld air pumps, and is particularly suitable for automated testing on production lines and after-sales service scenarios.

[0091] As mentioned in Embodiment 1, the digital display screen can display a modulated light signal synchronized with the wind speed test results. In this embodiment, the specific implementation of such a modulated light signal includes a brightness flashing sequence or color switching frequency that encodes the current wind speed test results.

[0092] Brightness flicker sequence encoding refers to the process where the main control unit, based on the measured wind speed value and according to a predetermined communication protocol, controls the backlight brightness of the digital display screen to change between light and dark in a specific time sequence. For example, encoding methods similar to Morse code or serial communication protocols (such as UART) can be used to convert the wind speed value into a series of high and low level signals, which are then represented by the on / off state of the screen. For instance, "bright" represents logic "1," and "dark" represents logic "0." In this way, a complete wind speed value can be transmitted through a short brightness flicker sequence. To improve communication reliability, the encoded sequence can also include start bits, stop bits, and parity bits.

[0093] For example, to transmit a specific wind speed value (e.g., 25.3 m / s), the main control unit can perform the following steps: First, a start signal is generated, and the display screen flashes continuously at a high frequency for a certain period of time to notify the external device to prepare to receive data. Then, data encoding is performed, which can be done using pulse counting. The main control unit controls the display screen to flash twice continuously (representing the tens digit "2"), pause for a short time, then flash five times continuously (representing the units digit "5"), pause again for a short time, and finally flash three times continuously (representing the decimal digit "3"). Finally, an end signal is generated to indicate that the transmission is complete.

[0094] Color switching frequency encoding refers to the ability of the main control unit to control the screen to switch between two or more colors at a specific frequency if the digital display supports color display (such as an RGB LED display). This switching frequency has a predetermined functional relationship with the measured wind speed value. For example, the higher the wind speed, the faster the color switching frequency. Alternatively, Frequency Shift Keying (FSK) can be used, with different frequencies representing logic "0" and "1". This method is less susceptible to ambient light interference compared to brightness flicker, and the information transmission rate may be higher.

[0095] To utilize this modulated light signal for calibration and verification, the system also includes an external light acquisition device. This device is typically placed at a test station on the production line or on an after-sales service bench. At the core of the external light acquisition device is a photoelectric sensor, such as a photodiode, photoresistor, or high-speed camera, used to capture the light signal emitted by the digital display screen.

[0096] During calibration and verification, the handheld digital display air pump is placed within the detection area of ​​the external light acquisition device, with its digital display facing the photoelectric sensor. The air pump enters a special calibration mode, begins performing wind speed testing, and simultaneously emits a modulated light signal through the digital display.

[0097] External light acquisition equipment captures these modulated light signals without physical electrical contact. The internal signal processing circuitry converts the captured light signals into electrical signals, which are then amplified, filtered, and shaped. The equipment's microprocessor then decodes these electrical signals to reconstruct the encoded wind speed test results.

[0098] After decoding, an external optical acquisition device can compare the wind speed value with a known standard wind speed value to verify the calibration accuracy of the handheld digital display air pump. For example, on a production line, the air pump can be placed in a standard air duct, and its actual wind speed can be measured using a high-precision anemometer. This standard value is then compared with the wind speed value obtained through optical signal decoding. If the error between the two is within the allowable range, the calibration is considered successful.

[0099] If a calibration deviation is detected, the external light acquisition device can also send calibration commands and parameters to the handheld air pump via optical signals or other wireless communication methods, dynamically adjusting its internal multi-level wind speed mapping table to achieve automated closed-loop calibration.

[0100] This calibration and verification method based on modulated optical signals offers significant advantages. First, it is non-contact, requiring no disassembly of equipment or connection cables, making operation simple and quick, and avoiding damage to the equipment. Second, optical signals offer high transmission speeds and strong resistance to electromagnetic interference, making them suitable for use in complex production environments. Furthermore, it utilizes the equipment's existing digital display screen as a signal transmitter, incurring virtually no additional hardware costs. This innovative testing and calibration method greatly improves production efficiency, reduces quality control costs, and facilitates after-sales service.

[0101] Furthermore, to achieve the aforementioned optical encoding output function, this invention designs a time-domain luminance modulation communication protocol (TD-LMC) that can be implemented using existing digital display backlights without additional hardware. This protocol converts wind speed values ​​into specific light pulse sequences for external photosensitive devices to read.

[0102] The protocol defines three basic signal states: high brightness (logic 1), low brightness (logic 0), and synchronization (used for frame header identification).

[0103] The communication sequence is as follows: First, the main control unit controls the display screen to enter the handshake phase, driving the backlight to alternate between full brightness and full darkness at a specific high frequency (e.g., 50Hz) for a duration of 200 milliseconds. This specific blinking pattern serves as the start frame header, triggering an interrupt in the acquisition of the external detection device, causing it to enter data receiving mode.

[0104] The data transmission phase then begins. The main control unit breaks down the current wind speed value (e.g., 25.6) into three independent numerical characters: 2, 5, and 6. For each digit, a pulse counting encoding method is used for transmission. For example, when transmitting the digit 2, the control screen generates two bright pulses with a duration of T (e.g., 50 milliseconds), with a low-brightness state T between the pulses. A long low-brightness state with a duration of 4T is inserted between the digits as a separator.

[0105] Decimal point information is identified through specific positional encoding or a single long, bright pulse. If a color display is used, frequency shift keying (FSK) color modulation can be further employed, for example, defining green as logic 1 and red as logic 0, and transmitting binary wind speed data streams by switching the color frequency.

[0106] At the end of the transmission, the screen enters a medium brightness state for one second as the end frame. External devices capture the above light intensity change sequence through photodiodes, decode it through a microprocessor to reconstruct the wind speed value, and compare it with the reading of a standard anemometer, thus completing factory calibration and accuracy verification under fully enclosed, non-contact conditions.

[0107] Example 6

[0108] This embodiment, based on Embodiment 1, further refines the processing method for real-time operating current signals, with a particular focus on how to accurately and robustly extract the ripple frequency components related to motor speed. In handheld air pumps operating at high speeds and with dynamically changing loads, current signals typically contain complex noise and interference, placing high demands on signal processing algorithms.

[0109] In this embodiment, the main control unit uses the Fast Fourier Transform (FFT) algorithm to process the real-time operating current signal. FFT is a highly efficient digital signal processing technique that can convert time-domain signals into frequency-domain signals, revealing the various frequency components and their amplitudes contained in the signal.

[0110] Compared to traditional time-domain analysis methods (such as zero-crossing detection or peak detection), the FFT algorithm has stronger noise immunity and higher frequency resolution. In the current signal of a handheld air pump, in addition to the useful ripple signal related to motor commutation, it may also contain interference signals from various sources such as PWM switching noise, electromagnetic interference, and mechanical vibration. The frequencies of these interference signals may be close to or overlap with the frequencies of the useful signal, making it difficult for time-domain analysis methods to accurately extract the target frequency.

[0111] The application process of the FFT algorithm is as follows: The main control unit first samples the real-time running current signal at a sufficiently high sampling rate to satisfy the Nyquist sampling theorem, ensuring that signal components within the target frequency range can be captured. Then, the main control unit accumulates a certain number of sampling points within a time window, forming a time series. Before performing FFT calculations, the sampled data needs to be preprocessed to improve the accuracy of spectral analysis. Preprocessing steps may include DC bias removal (eliminating the DC component in the current signal), windowing (such as Hanning or Blackman windows to reduce spectral leakage in FFT analysis), and filtering.

[0112] Next, the main control unit performs an FFT operation on the preprocessed current sample to obtain the current signal spectrum within that time window. The horizontal axis of the spectrum represents frequency, and the vertical axis represents the amplitude or power of that frequency component.

[0113] In the spectrum diagram, the main control unit needs to identify the fundamental frequency related to the commutation frequency of the motor in the air pump assembly. Ideally, due to the periodicity of the motor commutation operation, a series of harmonic components with the commutation frequency as the fundamental frequency will appear in the current signal. These harmonic components will appear as a series of spikes in the spectrum diagram.

[0114] The main control unit can accurately identify the fundamental frequency representing the motor's commutation frequency by searching for peaks in the frequency spectrum and combining this with the number of pole pairs of the motor and the current drive mode (e.g., six-step commutation method or sinusoidal wave drive). During the identification process, some intelligent algorithms may be needed to eliminate spurious peaks and interference frequencies. For example, the main control unit can track the change trajectory of the fundamental frequency over time and use its continuity to eliminate abrupt noise points.

[0115] Once the fundamental frequency is identified, the main control unit uses it as a proxy variable for the physical rotational speed of the fan blades inside the air pump assembly. Since the motor rotor and fan blades are rigidly connected, there is a definite proportional relationship between the motor's physical rotational speed and the fundamental frequency. Therefore, by accurately measuring the fundamental frequency, the real-time rotational speed of the motor can be calculated with high precision.

[0116] Using the FFT algorithm to extract ripple frequency components and employing the fundamental frequency as a proxy variable for rotational speed offers several advantages. First, it provides extremely high accuracy and resolution in rotational speed measurement, leading to more accurate subsequent aerodynamic load calculations and wind speed estimations. Second, it is insensitive to changes in the amplitude of the current signal, maintaining stable speed tracking even when battery voltage fluctuations or load variations cause changes in current amplitude. Furthermore, by analyzing harmonic components in the frequency spectrum, it is possible to extract other information about the motor's operating status, such as rotor eccentricity and bearing wear, providing support for equipment fault diagnosis and predictive maintenance.

[0117] To further improve the robustness of fundamental frequency extraction, the main control unit can also employ some auxiliary techniques. For example, phase-locked loop (PLL) technology can be used to track and filter the fundamental frequency detected by FFT to smooth the speed measurement results and reduce the impact of transient interference. Alternatively, motor models and observer techniques (such as sliding mode observers or Kalman filters) can be combined to estimate and verify the speed, thereby improving the reliability of the measurement.

[0118] In summary, this embodiment achieves high-precision and robust measurement of motor speed by introducing the FFT algorithm for frequency domain analysis of the current signal, laying a solid foundation for the entire sensorless wind speed testing system.

[0119] Furthermore, to address the technical challenge of weak ripple signals in motor operating current that are easily interfered with by PWM switching noise, this invention designs a multi-stage signal processing pipeline to ensure the purity and accuracy of ripple frequency extraction.

[0120] This processing flow does not rely on simple zero-crossing detection, but instead employs frequency domain analysis. The specific flow is as follows: Synchronous sampling mechanism: The analog-to-digital converter (ADC) of the main control unit is configured to be triggered synchronously with the PWM carrier signal of the motor drive. The sampling point is precisely set at the midpoint of the PWM conduction cycle. This can avoid the ringing noise and spike interference generated by the instantaneous switching of MOSFETs to the greatest extent and obtain a relatively pure phase current fundamental frequency.

[0121] Windowing and preprocessing: Before entering the frequency domain transformation, the acquired time-domain current sequence is processed by applying a Hanning window to suppress spectral leakage and improve frequency resolution.

[0122] Spectrum Peak Locking: After Fast Fourier Transform (FFT), the time-domain signal is converted into a spectrum. The main control unit runs a peak search algorithm to scan the fundamental component with the largest energy amplitude within a preset motor operating frequency range.

[0123] Harmonic filtering and confidence verification: To prevent the algorithm from erroneously locking onto the PWM carrier frequency or mechanical resonant frequency, the system sets a dynamic frequency confidence interval. This interval is dynamically adjusted in real time based on the current duty cycle and bus voltage. Only spectral peaks falling within this confidence interval are considered valid motor commutation ripple frequencies and participate in subsequent wind speed calculations.

[0124] Example 7

[0125] This embodiment optimizes the structure and usage of the preset multi-level wind speed mapping table based on Embodiment 1 to adapt to a wider range of bus voltage variations and further improve the accuracy of wind speed testing. In Embodiment 1, the wind speed mapping table is used to convert theoretical aerodynamic load values ​​into wind speed values. However, in practical applications, the aerodynamic characteristics and efficiency of the motor change nonlinearly with variations in bus voltage, making it difficult for a single mapping table to maintain high accuracy under all voltage conditions.

[0126] Especially in battery-powered handheld devices, the bus voltage can fluctuate within a wide range. For example, the full-charge voltage of a lithium battery pack may be more than 30% higher than its discharge cutoff voltage. At different voltage levels, even with the same theoretical aerodynamic load, the corresponding actual output wind speed may differ. This is because factors such as motor efficiency, winding copper losses, and iron losses are all voltage-dependent.

[0127] To address this issue, this embodiment proposes a wind speed mapping table structure containing multiple sets of calibration curves. Each set of calibration curves corresponds to a specific range of real-time bus voltage values. For example, if the bus voltage range is 12V to 16.8V, this range can be divided into multiple sub-ranges, such as 12V-13V, 13V-14V, 14V-15V, 15V-16V, and 16V-16.8V. For each sub-range, an independent set of calibration curves is obtained through experimental calibration during the product development phase. This set of curves describes the relationship between the theoretical aerodynamic load value and the wind speed within that voltage range.

[0128] The construction process of this multidimensional mapping table is as follows: During the product development phase, a systematic calibration test of the handheld air pump needs to be performed under the power supply of a programmable DC power supply. Within each voltage range, a representative voltage value is selected, and the bus voltage is stabilized at that value. Then, by changing the motor drive parameters, the air pump assembly is operated under different aerodynamic loads, while a high-precision anemometer is used to measure the actual wind speed. The theoretical aerodynamic load value and the actual wind speed value corresponding to each operating point are recorded. By performing curve fitting on these data points, multiple sets of calibration curves covering the entire voltage range are finally obtained.

[0129] The collection of these calibration curves together constitutes an optimized multi-level wind speed mapping table. Compared to the single mapping table in Example 1, this mapping table adds a dimension, namely the bus voltage dimension.

[0130] During wind speed testing, the main control unit first detects the current real-time bus voltage value. Then, based on this voltage value, the main control unit selects a corresponding calibration curve. For example, if the current bus voltage is 14.5V, the main control unit will select a calibration curve in the 14V-15V range.

[0131] After selecting the calibration curve, the main control unit uses the calculated theoretical aerodynamic load value to perform interpolation calculations on the curve to obtain the current wind speed test results. The interpolation calculation method can be linear interpolation, polynomial interpolation, or spline interpolation to ensure the smoothness and accuracy of the calculation results.

[0132] To further improve accuracy, two-dimensional interpolation can be performed between different calibration curves. For example, if the current bus voltage is 14.5V, which falls precisely between the 14V and 15V curves, the main control unit can calculate the corresponding wind speed values ​​on both the 14V and 15V curves. Then, a weighted average of these two wind speed values ​​is calculated (based on the weighting coefficients calculated according to the relative position of the current voltage between these two calibration voltage points) to obtain the final wind speed test result. This two-dimensional interpolation method can more accurately simulate the continuity of motor performance with voltage variations.

[0133] By employing this multi-dimensional wind speed mapping table and dynamically selecting calibration curves, this embodiment effectively eliminates the impact of bus voltage fluctuations on wind speed measurement accuracy. Regardless of whether the battery is fully charged or low, the system provides consistent and accurate wind speed readings. This is significant for improving product performance stability and user experience throughout its entire lifespan.

[0134] Example 8

[0135] This embodiment, based on Embodiment 1, considers the dynamic characteristics of handheld devices during use, particularly the impact of user-induced hand-held shaking and posture changes on wind speed testing accuracy, and proposes a corresponding compensation mechanism. Handheld air pumps are inevitably affected by the vibration, movement, and rotation of the user's hand during use. These mechanical movements interfere with the operation of the air pump components, thereby affecting the stability of the current signal.

[0136] Especially when the high-speed motor in the air pump assembly is running, its rotor has a large angular momentum, generating a significant gyroscopic effect. When the user quickly changes the posture of the handheld air pump, the gyroscopic effect generates a torque that resists the change in posture, acting on the motor's bearings and housing. This additional mechanical load causes instantaneous fluctuations in motor speed and disturbances in the current signal. If this signal noise generated by the gyroscopic effect is mixed into the current signal used for wind speed calculation, it will lead to fluctuations and errors in the wind speed test results.

[0137] To monitor the motion of the handheld air pump in real time and eliminate its impact on wind speed testing, this embodiment integrates an inertial measurement unit (IMU) into the system. An IMU typically includes an accelerometer and a gyroscope, capable of measuring the device's acceleration and angular velocity in three-dimensional space. The IMU connects to the main control unit via a high-speed communication interface (such as SPI or I2C).

[0138] During the wind speed test, the main control unit reads the output data of the IMU in real time and calculates the shaking amplitude and attitude change rate of the handheld air pump through attitude calculation algorithms (such as Kalman filtering or complementary filtering).

[0139] The main control unit uses this information to assess whether the current motion state of the device is stable. The system presets a stability threshold, which defines the maximum allowable jitter amplitude or attitude change rate. When the detected jitter amplitude exceeds this stability threshold, the main control unit determines that the device is in a dynamically unstable state and needs to activate the compensation mechanism.

[0140] The core of the compensation mechanism is to apply an adaptive filtering algorithm to the real-time operating current signal. This filtering algorithm aims to eliminate signal noise caused by the gyroscopic effect on the rotor of the air pump assembly, while retaining the useful signal components related to the pneumatic load.

[0141] The design of filtering algorithms can be dynamically adjusted based on the motion parameters measured by the IMU. For example, a notch filter can be designed whose center frequency and bandwidth are adjusted in real time according to the angular velocity measured by the IMU to accurately filter out noise of specific frequencies related to the gyroscopic effect.

[0142] Another more advanced method is model-based compensation. During product development, a mathematical model of the impact of gyroscopic effects on the operating current signal can be established through experimental testing and simulation analysis. This model takes the motor's speed, IMU-measured acceleration, and angular velocity as inputs, and outputs an estimate of the current noise caused by the gyroscopic effect. During real-time testing, the main control unit calculates the current noise estimate based on this model and subtracts it from the measured current signal to obtain a purified current signal. This purified current signal is then used for subsequent ripple frequency extraction and aerodynamic load calculation.

[0143] In addition, when the equipment is under severe vibration, the main control unit can temporarily reduce the update frequency of the wind speed test results or average multiple consecutive test results to reduce jumps in the displayed results and improve the stability of the readings.

[0144] By introducing an inertial measurement unit and an adaptive filtering algorithm, this embodiment effectively solves the problem of decreased wind speed testing accuracy in dynamic usage scenarios for handheld devices. Whether the user is stationary or moving, the system provides stable and reliable wind speed readings. This greatly expands the application scenarios of handheld air pumps and improves the user experience in complex environments.

[0145] Example 9

[0146] This embodiment optimizes the user interface design of the digital display screen based on Embodiment 1 to provide richer information display and a more intuitive user experience. In handheld air pumps, users are not only concerned with the wind speed, but also with information such as the device's load and battery life.

[0147] In this embodiment, the digital display screen is configured as a partitioned display interface to clearly and systematically display various types of information. The interface is mainly divided into two partitions: a first partition and a second partition.

[0148] The first section displays the core wind speed values. This section is usually located in a prominent position on the screen, using large fonts and high contrast to ensure users can quickly and accurately read the wind speed information. The units of the wind speed values ​​(such as meters per second or miles per hour) can also be displayed in this section.

[0149] The second section displays a dynamic bar chart representing the load percentage of the motor drive module. The load percentage refers to the proportion of the current motor output power to its maximum rated power, intuitively reflecting the current workload of the equipment. The dynamic bar chart is a very intuitive visual representation; users can quickly understand the current load level by observing the length or fill ratio of the bars. For example, when the air pump is running at a low fan speed, the bar is shorter, indicating a lower load; when running at a high fan speed, the bar is longer, indicating a higher load.

[0150] The main control unit calculates the load percentage based on the theoretical aerodynamic load value obtained in real time and the maximum load capacity of the current gear. The calculation method is to divide the current theoretical aerodynamic load value by the maximum load capacity and then convert it into a percentage form.

[0151] To enhance visual appeal, bar charts can use different colors to represent different load levels. For example, green indicates low load (safe and efficient zone), yellow indicates medium load, and red indicates high load (approaching the limit).

[0152] Displaying the load percentage is crucial for users to use the equipment appropriately. For example, users can use the load to determine whether the current fan speed setting is suitable for the application scenario, or whether the equipment is nearing its performance limits. In cases of slight airflow obstruction, the load percentage may rise abnormally, prompting the user to check the airflow path.

[0153] To provide smooth, real-time information feedback, this embodiment also optimizes the refresh rate of the display interface. When the main control unit executes the wind speed test mode, it collects and calculates data at a certain sampling frequency. To ensure that the displayed content is synchronized with the system status, the main control unit adjusts the refresh rate of the second partition (dynamic bar graph) to match the sampling frequency of the wind speed test mode.

[0154] This means that when the system responds quickly to changes in load, the dynamic bar chart updates rapidly without any delay or stuttering. This high refresh rate dynamic display not only enhances the visual experience but also allows users to more acutely perceive real-time changes in the device's status.

[0155] For example, in the closed-loop constant speed control process described in Example 4, the user can observe through a dynamic bar graph how the system automatically adjusts its output power to maintain a constant wind speed. When the battery voltage drops, the user will see the bar graph gradually lengthen, indicating that the system is increasing the load percentage to compensate for the voltage drop.

[0156] To achieve high refresh rates, the main control unit needs to employ efficient display driver technologies. For example, Direct Memory Access (DMA) technology can be used to transfer display data to the display controller at high speed, reducing the CPU load. Alternatively, partial refresh technology can be used to update only the changed display areas, improving refresh efficiency.

[0157] In summary, this embodiment provides users with rich, intuitive, and real-time information feedback through a reasonable partitioned display interface design and optimized refresh rate control, significantly improving the ease of use and intelligence level of the handheld air pump.

[0158] Example 10

[0159] This embodiment provides a method for conducting multi-level wind speed tests using a handheld digital display screen air pump multi-level wind speed testing system as described in Embodiments 1 to 9. The method summarizes the system's workflow in actual operation and demonstrates how various technical features are integrated into a coordinated whole. (Refer to...) Figure 2The method includes the following steps: Step S1: Enter test mode, the main control unit obtains the real-time bus voltage of the power supply module.

[0160] When the user turns on the handheld air pump and selects a fan speed setting, the system automatically enters the fan speed test mode. The main control unit first initiates real-time monitoring of the bus voltage at the output of the power supply module. As described in Example 1, this is achieved through ADC sampling and digital filtering. The acquisition of the real-time bus voltage is fundamental to all subsequent calculations and controls. If the system integrates a BMS (as described in Example 2), the main control unit will also acquire parameters such as the battery internal resistance in this step to prepare for subsequent voltage compensation calculations.

[0161] Step S2: Drive the air pump assembly to run at the preset initial duty cycle corresponding to the target gear.

[0162] The main control unit retrieves a preset initial duty cycle value from memory based on the user-selected target wind speed. This initial duty cycle is set based on experience or historical data, aiming to enable the air pump assembly to start quickly and approach the target wind speed. The motor drive module generates a corresponding drive signal via the PWM controller based on this initial duty cycle, driving the air pump assembly to start operating. If the system employs closed-loop constant speed control (as described in Example 4), this initial duty cycle will serve as the starting point or feedforward term of the closed-loop control algorithm.

[0163] Step S3: Collect the real-time operating current and extract the current ripple frequency.

[0164] During the operation of the air pump assembly, the main control unit acquires the operating current signal flowing through the motor in real time through a current sampling circuit. The acquisition process uses a high-speed ADC to capture the high-frequency ripple component in the current signal. After acquiring the real-time operating current signal, the main control unit executes a signal processing algorithm to extract the current ripple frequency. As described in Example 6, the main control unit uses an FFT algorithm to convert the time-domain current signal into a frequency-domain spectrum and identifies the fundamental frequency related to the motor commutation frequency using a peak detection algorithm. This fundamental frequency is used as a proxy variable for the motor's real-time speed. If the system integrates an IMU (as described in Example 8), the main control unit will also adaptively filter the current signal based on the IMU data to eliminate noise interference caused by the gyroscope effect.

[0165] Step S4: Retrieve the voltage-frequency-wind speed mapping relationship from the memory.

[0166] The main control unit retrieves a preset voltage-frequency-wind speed mapping relationship from non-volatile memory. This mapping relationship describes the characteristics of the air pump's output wind speed under different power supply voltages and motor speeds (characterized by current ripple frequency). As described in Example 7, this mapping relationship may contain multiple calibration curves to accommodate different voltage ranges. The main control unit selects a suitable mapping relationship or calibration curve based on the currently measured bus voltage value.

[0167] Step S5: Based on the extracted current ripple frequency and the real-time bus voltage, calculate the compensated wind speed value in the mapping relationship.

[0168] The main control unit uses the real-time bus voltage and the extracted current ripple frequency as input parameters, and performs calculations within the retrieved mapping relationship to obtain the current wind speed value. The calculation process first selects a suitable calibration curve or performs two-dimensional interpolation calculations based on the real-time bus voltage. Then, it searches for or interpolates the corresponding wind speed value within the mapping relationship based on the current ripple frequency. During the calculation process, the main control unit also executes various compensation algorithms, such as voltage drop compensation based on battery internal resistance parameters (as described in Example 2), or airflow obstruction determination and correction based on the temperature rise rate (as described in Example 3). The final result is an accurate wind speed value after multiple compensations and corrections.

[0169] Step S6: Generate visual output on a digital display screen, the output including modulated display parameters to encode the compensated wind speed value for external optical verification.

[0170] Finally, the main control unit sends the calculated compensated wind speed value to the digital display screen for display. The visual output can be an intuitive numerical display or a dynamic bar graph (as described in Embodiment 9). Simultaneously, to support non-contact rapid calibration and verification, the main control unit also controls the digital display screen to generate a modulated light signal. As described in Embodiment 5, the main control unit encodes the compensated wind speed value into the light signal by modulating display parameters (such as brightness flicker sequence or color switching frequency). An external light acquisition device can quickly verify the accuracy of the wind speed measurement by capturing and decoding this light signal.

[0171] The entire testing process is executed in a loop. The main control unit updates the wind speed measurement results in real time and performs closed-loop control and protection as needed to ensure the stable and efficient operation of the handheld digital display air pump.

[0172] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A multi-speed wind speed testing system for a handheld digital display air pump, characterized in that, include: Main control unit, power supply module, motor drive module, air pump assembly, and digital display screen; The digital display screen is electrically connected to the main control unit and is used to dynamically display the current wind speed test results; The main control unit is configured to perform a wind speed test mode, which includes the following steps: The real-time bus voltage value of the power supply module and the real-time operating current signal of the motor drive module are collected. Frequency domain analysis processing is performed on the real-time operating current signal to extract the commutation ripple frequency component that is positively correlated with the motor speed; The real-time bus voltage value and the commutation ripple frequency component are processed using a relational model calibrated from experimental data to calculate the theoretical aerodynamic load value borne by the air pump assembly at the current moment. The calculated theoretical aerodynamic load value is matched with the preset multi-level wind speed mapping table stored inside the main control unit, and interpolation is used to generate the current wind speed test result.

2. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The power supply module includes a battery management system; The main control unit is configured to obtain battery state-of-charge parameters and battery internal resistance parameters from the battery management system. When calculating the theoretical aerodynamic load value, the main control unit applies a compensation coefficient based on the battery internal resistance parameter to correct the deviation of the operating current signal caused by the voltage drop of the power supply module.

3. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The main control unit includes a thermal monitoring interface, which is connected to a temperature sensor located on the discharge circuit of the power supply module. The main control unit calculates the temperature rise rate of the power supply module within a preset test cycle; When the temperature rise rate exceeds the safety threshold corresponding to the currently selected gear, the main control unit determines that the airflow is obstructed and generates a wind speed zeroing or error correction signal.

4. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The motor drive module includes a pulse width modulation controller; The main control unit dynamically adjusts the duty cycle of the pulse width modulation controller based on the difference between the theoretical aerodynamic load value and the target wind speed value at the current gear, thereby forming a closed-loop constant speed control. The digital display screen updates the current wind speed test results in real time to reflect the steady-state wind speed after closed-loop adjustment.

5. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The digital display screen is configured to perform optical encoding output function; Under the optical encoding output function, the digital display screen controls the brightness flashing sequence or color switching frequency of the display interface according to the current wind speed test result, and generates a modulated light signal containing wind speed numerical information. The modulated light signal is configured for non-contact reading and decoding by external optical detection equipment.

6. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The main control unit uses a fast Fourier transform algorithm to process the real-time operating current signal to extract the commutation ripple frequency component.

7. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The preset multi-level wind speed mapping table contains multiple sets of calibration curves, each set of calibration curves corresponding to a specific range of the real-time bus voltage value. The main control unit selects a corresponding calibration curve based on the currently detected real-time bus voltage value to perform interpolation calculations on the wind speed test results.

8. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, It also includes an inertial measurement unit connected to the main control unit; The main control unit detects the vibration amplitude of the handheld digital display screen air pump through the inertial measurement unit; When the jitter amplitude exceeds the stability threshold, the main control unit applies a filtering algorithm to the real-time operating current signal to eliminate signal noise caused by the gyro effect on the rotor of the air pump assembly.

9. The multi-speed wind speed testing system for a handheld digital display air pump according to claim 1, characterized in that, The digital display screen includes a partitioned display interface. The first partition displays the wind speed value, and the second partition displays a dynamic bar chart representing the load percentage of the motor drive module. The main control unit adjusts the refresh rate of the second partition to match the sampling frequency of the wind speed test mode.

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