A high-speed brushless motor electromagnetic noise reduction and vibration suppression method and system

Abstract

The application provides a high-speed brushless motor electromagnetic noise reduction and vibration suppression method and system, belonging to the computer technology field, which comprises the following steps: determining the rotating speed according to the rotor position data, and determining the load current according to the three-phase current data; when the rotating speed is greater than or equal to a preset rotating speed threshold and the load current corresponds to a negative current within a preset current interval, performing coordinate transformation on the three-phase current data, and extracting the fundamental current component; determining the target characteristic harmonic related to electromagnetic noise according to the fundamental current component, extracting the amplitude and phase of the target characteristic harmonic, and generating a reverse harmonic current; based on the superposition of the reverse harmonic current and the fundamental current, a target fundamental current instruction is generated; in a preset switching period, the carrier frequency is changed in a pseudo-random sequence, and a pulse width modulation control instruction is generated; based on the target fundamental current instruction and the pulse width modulation control instruction, a double-strategy cooperative driving instruction is generated, and the brushless motor is processed based on the double-strategy cooperative driving instruction.

Description

Technical Field

[0001] This application relates to the field of computer technology, and in particular to a method and system for electromagnetic noise reduction and vibration suppression of high-speed brushless motors. Background Technology

[0002] Brushless motors have been widely used in home appliances, automobiles, and industrial equipment, but electromagnetic noise and vibration at high speeds have become a bottleneck restricting their application expansion. This type of noise mainly originates from the periodic electromagnetic force generated by the interaction between air gap magnetic field harmonics and the stator and rotor, superimposed with switching frequency sideband harmonics caused by pulse width modulation. As the speed increases, this excites resonance in the motor structure, resulting in a significant high-frequency howling sound, mostly concentrated in the frequency range sensitive to the human ear. Traditional solutions suffer from drawbacks such as torque loss and increased cost, and are difficult to adapt to the dynamic noise characteristics under high-speed conditions. Single control strategies either fail to reduce specific characteristic harmonics or struggle to disperse broadband sideband noise, resulting in limited noise reduction and vibration suppression effects.

[0003] With the increasing demand for quiet operation due to consumption upgrades, there is an urgent need for a method and system for electromagnetic noise reduction and vibration suppression of high-speed brushless motors, in order to effectively suppress electromagnetic noise and vibration at high speeds and under specific load ranges. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method and system for electromagnetic noise reduction and vibration suppression of high-speed brushless motors.

[0005] A first aspect of this application provides a method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor, comprising: Collect three-phase current data, rotor position data, and bus voltage data of the brushless motor; Based on the rotor position data, the rotational speed is determined; based on the three-phase current data, the load current is determined. When the rotational speed is greater than or equal to a preset rotational speed threshold and the negative current corresponding to the load current is within a preset current range, the three-phase current data is transformed into a synchronous rotating coordinate system, and the fundamental current component is extracted. Based on the fundamental current component, the target characteristic harmonics related to electromagnetic noise are determined, and the amplitude and phase of the target characteristic harmonics are extracted. Based on the amplitude and phase of the target characteristic harmonic, a reverse harmonic current with the same amplitude but opposite phase to the target characteristic harmonic is generated. The reverse harmonic current is superimposed on the fundamental current to generate a target fundamental current command. Within a preset switching cycle, the carrier frequency is changed using a pseudo-random sequence to obtain a random carrier frequency, and a pulse width modulation control command is generated. Based on the target fundamental current command and the pulse width modulation control command, a dual-strategy collaborative drive command is generated, and noise reduction and vibration suppression processing are performed on the brushless motor based on the dual-strategy collaborative drive command.

[0006] A second aspect of this application provides an electromagnetic noise reduction and vibration suppression system for a high-speed brushless motor, comprising: The multi-source data acquisition module is used to collect three-phase current data, rotor position data, and bus voltage data of the brushless motor. The speed-load determination module is used to determine the speed based on the rotor position data and the load current based on the three-phase current data. The coordinate transformation extraction module is used to perform coordinate transformation on the three-phase current data, convert it to a synchronous rotating coordinate system, and extract the fundamental current component when the rotational speed is greater than or equal to a preset rotational speed threshold and the negative current corresponding to the load current is within a preset current range. The reverse harmonic generation module is used to determine the target characteristic harmonic related to electromagnetic noise based on the fundamental current component, and extract the amplitude and phase of the target characteristic harmonic; generate a reverse harmonic current with the same amplitude and opposite phase as the target characteristic harmonic based on the amplitude and phase of the target characteristic harmonic; and generate a target fundamental current command based on the superposition of the reverse harmonic current and the fundamental current. The random carrier frequency modulation module is used to change the carrier frequency with a pseudo-random sequence within a preset switching period to obtain a random carrier frequency and generate pulse width modulation control commands. The collaborative drive control module is used to generate a dual-strategy collaborative drive command based on the target fundamental current command and the pulse width modulation control command, and to perform noise reduction and vibration suppression processing on the brushless motor based on the dual-strategy collaborative drive command.

[0007] A third aspect of this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor.

[0008] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor.

[0009] The beneficial effects of the electromagnetic noise reduction and vibration suppression method and system for high-speed brushless motors provided in this application are as follows: By identifying target characteristic harmonics within a specific negative current range at high speeds, and actively canceling them by injecting reverse harmonic current into the fundamental current, this application weakens stator vibration and audible noise caused by electromagnetic force harmonics at the source, thus suppressing discrete howling in sensitive frequency bands. Simultaneously, the pseudo-random sequence dynamically adjusts the carrier frequency, dispersing concentrated switching sideband harmonic energy across a wide frequency band, effectively reducing electromagnetic interference peaks and the risk of structural resonance. Furthermore, the generation of dual-strategy collaborative drive commands effectively reduces motor operating noise and vibration amplitude. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating a method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to an embodiment of this application. Figure 2 This is a structural block diagram of a high-speed brushless motor electromagnetic noise reduction and vibration suppression system provided in an embodiment of this application; Figure 3 This is a schematic block diagram of an electronic device provided in an embodiment of this application.

[0011] Explanation of reference numerals in the attached figures: 20. High-speed brushless motor electromagnetic noise reduction and vibration suppression system; 21. Source data acquisition module; 22. Speed ​​and load determination module; 23. Coordinate transformation extraction module; 24. Reverse harmonic generation module; 25. Random carrier frequency modulation module; 26. Cooperative drive control module 300. Electronic device; 301. Processor; 302. Input device; 303. Output device; 304. Memory; 305. Communication bus. Detailed Implementation

[0012] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0013] To make the purpose, technical solution, and advantages of this application clearer, the following will be described in conjunction with the appendix. Figure 1 - Appendix Figure 3 The following is an explanation using specific examples.

[0014] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to an embodiment of this application. The method includes: S101: Collects three-phase current data, rotor position data, and bus voltage data of the brushless motor.

[0015] In this embodiment, the three-phase current data represents the core indicator of the motor's electromagnetic state. It is collected by current sensors (Hall current sensor, shunt resistor sampling module), and the collected data needs to be filtered to eliminate noise caused by power supply ripple and electromagnetic interference.

[0016] The acquisition of rotor position data affects the accuracy of speed calculation and coordinate transformation. Incremental encoders or magnetic encoders are used to capture rotor magnetic pole position signals in real time and output pulse signals to calculate rotor mechanical angles and speeds. The sampling resolution meets the dynamic response requirements at high speeds.

[0017] The acquisition of bus voltage data is based on the power supply status on the power supply side. A voltage divider sampling circuit or a dedicated voltage sensor is used to monitor the voltage fluctuation of the DC bus. This line voltage data not only provides a reference value for the subsequent generation of pseudo-random carrier frequency, but also indicates the stability of the power supply system.

[0018] The acquisition of the three types of data is synchronized in time through hardware triggering or software synchronization mechanisms, ensuring that the current, position, and voltage data at the same moment correspond and match. The acquired three-phase current data, rotor position data, and bus voltage data are transmitted to the controller's storage unit in real time.

[0019] S102: Determine the rotational speed based on the rotor position data, and determine the load current based on the three-phase current data.

[0020] In this embodiment, the rotor position data includes the temporal change information of the rotor mechanical angle. The rotational speed can be calculated using the time difference method or pulse counting method, based on the pulse signals output by the incremental encoder or magnetic encoder. Specifically, the time interval between two adjacent position pulses is recorded, and the encoder resolution (number of pulses per revolution) is integrated. The instantaneous rotational speed is calculated using the ratio of the mechanical angle change to the time difference. Furthermore, a moving average filtering algorithm is used to perform a weighted average of the instantaneous rotational speeds over multiple consecutive cycles, smoothing speed fluctuations and improving speed stability.

[0021] Three-phase current data are instantaneous values, requiring the extraction of load current characteristics through effective value calculation or vector synthesis methods. Specifically, for balanced three-phase operation, the effective value of the three-phase current is calculated using the root mean square formula as a quantitative indicator of the load current. If three-phase current imbalance exists, or if unstable anomalies such as jumps, missed points, or noise distortion occur in the sampling of a certain phase current, the three-phase current data is reconstructed using single-phase current substitution + phase compensation method before load current calculation. For example, based on the inherent electrical characteristic of a 120° phase difference between the three-phase currents of a brushless motor, phase compensation logic is triggered when any one of the three phases (A, B, and C) current data is detected to be abnormal. The phase compensation logic assumes an abnormality in the A-phase current sampling. Based on the effective current signals of phases B and C, it calculates the equivalent A-phase current using the trigonometric function phase derivation formula (i_A = -i_B - i_C, where i_A, i_B, and i_C are the instantaneous currents of the three phases, respectively), thus completing the full reconstruction of the three-phase current. If two or more phases are detected to be abnormal at the same time, the fault degradation mechanism is activated, and the smoothed value of the historical load current is temporarily used for interpolation estimation.

[0022] S103: When the rotational speed is greater than or equal to the preset rotational speed threshold and the negative current corresponding to the load current is within the preset current range, the three-phase current data is transformed into a synchronous rotating coordinate system and the fundamental current component is extracted.

[0023] In this embodiment, the preset speed threshold and negative current range are dynamically calibrated based on the motor's rated parameters, structural characteristics, and application scenarios. Specifically, the speed threshold is set to 70%-80% of the motor's rated speed. Within this range, the electromagnetic harmonic frequency of the motor increases, which superimposes with the structural resonant frequency, resulting in increased noise and vibration. The negative current range is determined based on the motor's load characteristics, corresponding to braking, deceleration, or reverse load conditions. Under these conditions, the current harmonic content surges, and additional electromagnetic torque pulsations are generated, making it a control range for noise reduction and vibration suppression. Furthermore, when the speed increases from below the speed threshold to the speed threshold, this state is maintained for three consecutive control cycles before triggering; when the negative current exceeds the preset current range, triggering stops after five consecutive control cycles without returning to the preset current range.

[0024] When the rotational speed is greater than or equal to a preset speed threshold and the negative current corresponding to the load current is within a preset current range, coordinate transformation is performed on the three-phase current data. Specifically, a two-step transformation strategy combining Clark transformation and Park transformation is adopted: first, the current data in the three-phase stationary coordinate system (abc) is converted to the two-phase stationary coordinate system (α-β) through Clark transformation to eliminate the coupling relationship of the three-phase current; then, based on the rotor electrical angle, the two-phase current components in the α-β coordinate system are transformed to the synchronous rotating coordinate system (dq) through Park transformation. During the transformation process, the rotor electrical angle is obtained by acquiring the rotor position pulse signal through an incremental encoder or magnetic encoder, and the rotor mechanical angle is calculated according to the encoder resolution; then, the rotor mechanical angle is multiplied by the number of motor pole pairs to obtain the real-time rotor electrical angle.

[0025] In a synchronous rotating coordinate system, the d-axis and q-axis currents include the fundamental DC component, low-order characteristic harmonics, and high-frequency noise components. Extracting the DC component from the d-axis and q-axis currents yields the fundamental current component.

[0026] S104: Based on the fundamental current component, determine the target characteristic harmonic related to electromagnetic noise, and extract the amplitude and phase of the target characteristic harmonic; based on the amplitude and phase of the target characteristic harmonic, generate a reverse harmonic current with the same amplitude and opposite phase as the target characteristic harmonic; based on the superposition of the reverse harmonic current and the fundamental current, generate the target fundamental current command.

[0027] In this embodiment, spectral analysis is performed on the fundamental current component to obtain current harmonics of different frequencies; the amplitude of the current harmonics is extracted, and current harmonics with amplitudes greater than a preset harmonic current threshold are used as candidate harmonics; based on the correlation database between the candidate harmonics and the preset switching frequency sideband harmonic order and audible noise, harmonics of human ear interest are obtained; harmonics associated with the resonant frequency of the motor structure are screened from the harmonics of human ear interest and identified as structural resonance harmonics; structural resonance harmonics that simultaneously satisfy the conditions of being located within the sensitive frequency band of human ear and being associated with the resonant frequency of the motor structure are identified as target characteristic harmonics.

[0028] This embodiment employs a Fast Fourier Transform with a Hanning window to decompose the steady-state amplitude and phase of the target characteristic harmonic at its corresponding frequency points. After obtaining the amplitude and phase of the target characteristic harmonic, based on the cancellation principle of equal amplitude and completely opposite phase, the target characteristic harmonic amplitude is used as the reference amplitude, and the original phase shifted by 180° is used as the reverse phase. In the current control time domain, a reverse harmonic current with the same frequency, same amplitude, and opposite phase is reconstructed. The reverse harmonic current can achieve vector cancellation with the original characteristic harmonic that generates noise and vibration from the electromagnetic excitation source, weakening the harmful harmonic components in the air gap electromagnetic force.

[0029] The target fundamental current command is obtained by vector superposition and fusion of the reverse harmonic current and the original fundamental current component. The superposition process follows the current vector synthesis rule, achieving coupling between the fundamental DC quantity and the reverse harmonic AC quantity in a synchronously rotating coordinate system. After superposition, the current closed-loop setpoint is readjusted to obtain a smooth target fundamental current command free from harmful harmonic disturbances. This target fundamental current command enables the high-speed brushless motor to output power normally and operate at a stable speed, while also suppressing electromagnetic noise and vibration associated with sensitive frequencies and structural resonances through active harmonic cancellation.

[0030] S105: Change the carrier frequency with a pseudo-random sequence within a preset switching cycle to obtain a random carrier frequency and generate a pulse width modulation control command.

[0031] In this embodiment, the bus voltage data is mapped using a voltage-frequency mapping relationship to obtain a carrier frequency reference value; the random number generated by the pseudo-random number generator in the current switching cycle is multiplied with the carrier frequency reference value to obtain the carrier frequency of the current switching cycle; the pulse width modulation timer cycle value is updated according to the initial random carrier frequency of the current switching cycle to obtain a random carrier frequency that changes periodically.

[0032] The random carrier frequency is written into the period register of the internal timer of the controller, and the timer counting period and counting amplitude are refreshed, so that the frequency of the triangular carrier waveform jumps randomly and irregularly.

[0033] In this embodiment, during the generation of pulse width modulation (PWM) control commands, the controller uses each switching cycle as the smallest unit to complete carrier amplitude matching, modulation wave interpolation fitting, and duty cycle calculation. After each random carrier switching cycle ends, the current PWM duty cycle state is immediately latched, generating six complementary and symmetrical PWM drive pulse commands. The switching cycle is the basic time period for the repeated changes of the PWM carrier, and also the smallest time unit for the controller's PWM, random frequency modulation, and current control. Modulation wave interpolation fitting involves interpolating and smoothing the instantaneous value of the sinusoidal modulation wave under the condition that the random carrier frequency changes periodically with unequal cycle lengths. The duty cycle is calculated based on the comparison between the current instantaneous value of the modulation wave and the carrier triangular wave, determining the proportion of the power switch's on-time within each switching cycle to the entire cycle.

[0034] S106: Based on the target fundamental current command and pulse width modulation control command, generate dual-strategy collaborative drive command, and perform noise reduction and vibration suppression processing on the brushless motor based on the dual-strategy collaborative drive command.

[0035] In this embodiment, after obtaining the target fundamental current command and the pulse width modulation control command, a dual-strategy collaborative fusion is performed to obtain a dual-strategy collaborative drive command. Specifically, the target fundamental current command represents an active harmonic cancellation control strategy, used to suppress electromagnetic vibration and structural resonance noise caused by inherent characteristic harmonics of the motor; the pulse width modulation control command represents a pseudo-random carrier spread spectrum modulation strategy, used to disperse high-frequency sideband harmonics and sharp howling caused by the fixed switching frequency. The two types of control commands do not operate independently, but are coupled and coordinated at the control timing layer within the controller to form a complementary and synergistic integrated drive command.

[0036] During the coordinated instruction generation process, the controller uses the switching cycle as the time reference and takes the target fundamental current instruction as the outer loop setpoint of the current closed loop, participating in the real-time adjustment of the d-axis and q-axis currents to correct the motor excitation current and torque current components. Simultaneously, it uses the duty cycle of the pulse width modulation generated under the random carrier and the drive pulse logic as the inner loop modulation execution instruction, following the changes in the modulation amplitude of the current closed loop. Furthermore, the adjustment cycle of current harmonic compensation is aligned with the switching cycle of the random pulse width modulation to achieve seamless cooperation between the active harmonic cancellation control strategy and the pseudo-random carrier spread spectrum modulation strategy.

[0037] After the dual-strategy collaborative drive command is generated, it is sent to the inverter bridge power drive unit to control the turn-on and turn-off timing of each power switching device in the three-phase inverter bridge. On the one hand, according to the target fundamental current command, the characteristic current harmonics that are sensitive to human hearing and excite structural resonance are canceled, thereby weakening low-frequency to mid-frequency vibration noise from the root of electromagnetic force; on the other hand, according to the random carrier pulse width modulation command, the energy is concentrated at the switching frequency, and the discrete peak harmonics are dispersed over a wide frequency range, weakening high-frequency howling.

[0038] From the above, it can be concluded that the beneficial effects of the electromagnetic noise reduction and vibration suppression method and system for high-speed brushless motors provided in this application are as follows: This application identifies target characteristic harmonics within a high-speed and specific negative current range, and actively cancels them by injecting reverse harmonic current into the fundamental current, thereby weakening stator vibration and audible noise caused by electromagnetic force harmonics at the source, and suppressing discrete howling in the sensitive frequency band. Simultaneously, the pseudo-random sequence dynamically adjusts the carrier frequency, dispersing the concentrated switching sideband harmonic energy across a wide frequency band, effectively reducing electromagnetic interference peaks and the risk of structural resonance. Furthermore, the generation of dual-strategy collaborative drive commands effectively reduces motor operating noise and vibration amplitude.

[0039] In one embodiment of this application, determining the target characteristic harmonics associated with electromagnetic noise based on the fundamental current component includes: Spectral analysis of the fundamental current component yields current harmonics of different frequencies. Extract the amplitude of current harmonics and select current harmonics with amplitudes greater than a preset harmonic current threshold as candidate harmonics; Based on the correlation database between candidate harmonics and preset switching frequency sideband harmonic orders and audible noise, harmonics of interest to the human ear are obtained. Harmonics associated with the resonant frequency of the motor structure are selected from the harmonics that are of interest to the human ear and identified as structural resonance harmonics. The target characteristic harmonics are determined by simultaneously satisfying the structural resonance harmonics that are located within the frequency band sensitive to human hearing and are associated with the resonant frequency of the motor structure.

[0040] In this embodiment, spectral analysis is performed on the fundamental current component to obtain current harmonics of different frequencies. Specifically, the fundamental current component is first preprocessed by windowing to suppress analysis errors caused by spectral leakage and the picket fence effect. Then, the fundamental current component is decomposed into frequencies across the entire domain using a spectral analysis algorithm to obtain current harmonics of different frequencies.

[0041] The amplitude of current harmonics is extracted, and harmonics with amplitudes greater than a preset harmonic current threshold are selected as candidate harmonics. Specifically, after completing the spectrum analysis, the amplitude of each different frequency current harmonic is quantitatively extracted. Amplitude, also called wave amplitude, represents the magnitude of the maximum deviation of the fluctuating signal from the center point. Using the harmonic current threshold as the initial screening criterion, current harmonics with amplitudes less than the harmonic current threshold are considered weak and have negligible contribution to electromagnetic noise and structural vibration, and are thus eliminated. Only harmonics with amplitudes greater than the harmonic current threshold are retained as candidate harmonics, which are current harmonics with the ability to cause vibration and noise disturbance. Specifically, under the stable and quiet operating conditions of the motor at rated speed and rated load, the steady-state fundamental current component is collected and the spectrum is analyzed. The amplitude distribution of all current harmonics across the entire frequency band is statistically analyzed, and the maximum value of all harmonic amplitudes under normal operating conditions without noise or resonance disturbance is taken as the harmonic current threshold.

[0042] The fundamental frequency is obtained by substituting the rotational speed corresponding to the candidate harmonic into the fundamental frequency formula. The order of the candidate harmonic is obtained by dividing the frequency of the current harmonic by the fundamental frequency. The orders of the candidate harmonics are analyzed, and the sideband harmonics generated by the switching frequency modulation are identified. The orders corresponding to the sideband harmonics are taken as the switching frequency sideband orders. A correlation database between the switching frequency sideband harmonic orders and audible noise is established based on the human hearing characteristic curve, the preset brushless motor structural transfer function, and the mathematical distribution of the switching frequency sideband orders. The correlation database includes the noise sensitivity level corresponding to each sideband order. The noise sensitivity level of the current candidate harmonic order is queried based on the correlation database to obtain the target noise sensitivity level. If the target noise sensitivity level is greater than the preset sensitivity threshold and the harmonic corresponding to the target noise sensitivity level belongs to the switching frequency modulation sideband, then the candidate harmonic is identified as a harmonic of human interest.

[0043] Harmonics associated with the resonant frequency of the motor structure are selected from the harmonics of interest to the human ear and identified as structural resonance harmonics. The frequency parameters of the selected harmonics of interest to the human ear are compared and matched one by one with the pre-tested and calibrated natural resonant frequencies of each order of the motor structure to determine whether the frequency of the harmonics of interest to the human ear falls within the resonant frequency band of the motor structure. If the harmonic frequency is close to or coincides with the resonant frequency of the motor structure, it is very easy to induce mechanical resonance in the stator core, housing, and rotor structure, amplifying the vibration amplitude and noise radiation level. These harmonics of interest to the human ear that meet the frequency coupling conditions are classified separately and defined as structural resonance harmonics.

[0044] The structural resonance harmonics that simultaneously satisfy the conditions of being located within the frequency range sensitive to human hearing and being associated with the resonant frequency of the motor structure are identified as target characteristic harmonics. Specifically, a final secondary screening is performed based on the structural resonance harmonics, strictly adhering to two conditions: first, the harmonic frequency is located within the frequency range sensitive to human hearing, possessing strong auditory perception; second, the harmonic frequency is associated with the resonant frequency of the motor structure, capable of exciting structural resonance and amplifying vibration noise. Structural resonance harmonics that simultaneously meet both constraints are uniformly classified as target characteristic harmonics. These target characteristic harmonics are the source of electromagnetic howling and mechanical vibration in high-speed brushless motors.

[0045] As can be seen from the above, this embodiment captures the harmonics of each frequency current by analyzing the spectrum of the fundamental current component, and only filters out candidate harmonics that meet the amplitude requirements, thus reducing invalid calculations. Furthermore, based on the correlation database, it matches the harmonics that are of interest to the human ear and selects harmonics that match the characteristics of human hearing and the resonant frequency of the motor structure, thereby weakening the vibration caused by structural resonance from the root. Finally, based on the target characteristic harmonics superimposed on the frequency bands sensitive to the human ear and the structural resonance, it achieves targeted suppression, which not only improves the accuracy of noise reduction and vibration suppression, but also reduces control redundancy, further improving the quietness and stability of the high-speed brushless motor.

[0046] In one embodiment of this application, harmonics of interest to the human ear are obtained based on rotor position data and a preset correlation database between switching frequency sideband harmonic orders and audible noise, including: The fundamental frequency is obtained by substituting the rotational speed corresponding to the candidate harmonic into the fundamental frequency formula. The order of the candidate harmonic is obtained by dividing the frequency of the current harmonic by the fundamental frequency. The order of the candidate harmonic is analyzed, and the sideband harmonic generated by the switching frequency modulation is determined. The order corresponding to the sideband harmonic is taken as the sideband order of the switching frequency. Based on the human hearing characteristic curve, the preset brushless motor structure transfer function, and the mathematical distribution of the switching frequency sideband order, a correlation database is established between the switching frequency sideband harmonic order and audible noise. The correlation database includes the noise sensitivity level corresponding to each sideband order. Based on the query of the noise sensitivity level of the current candidate harmonic order in the associated database, the target noise sensitivity level is obtained. If the target noise sensitivity level is greater than the preset sensitivity threshold and the harmonic corresponding to the target noise sensitivity level belongs to the switching frequency modulation sideband, then the candidate harmonic is identified as a harmonic of human ear interest.

[0047] In this embodiment, firstly, the fundamental frequency is obtained by substituting the rotational speed corresponding to the candidate harmonic into the fundamental frequency formula. Then, the order of the candidate harmonic is obtained by dividing the frequency of the current harmonic by the fundamental frequency. According to the formula: f1 = P·n / 60, f1 is the fundamental frequency in Hz; P is the number of pole pairs of the motor; n is the mechanical rotational speed of the motor in r / min (revolutions per minute). This formula indicates that the rotor rotates n revolutions per minute, and each electrical cycle has P pairs of magnetic poles. Dividing by 60 to convert to per second gives the fundamental frequency of the stator current and magnetic field. The formula for calculating the order of the candidate harmonic is: k = f2 / f1, where k is the order of the candidate harmonic; f1 is the fundamental frequency, representing the basic frequency of the main magnetic field and main current during normal motor operation; and f2 is the harmonic frequency, representing the additional interference frequencies in the current spectrum.

[0048] Secondly, by comparing the mathematical correlation between candidate harmonic orders and switching frequency and fundamental frequency, the distribution characteristics of sideband harmonic orders centered on the switching frequency and spaced at the fundamental frequency are identified. The distribution characteristics of sideband harmonic orders are used to distinguish mechanical harmonics, electromagnetic harmonics and switch-modulated sideband harmonics, and to eliminate interference harmonic orders generated by non-switching frequency modulation.

[0049] During database construction, based on the A-weighted characteristic curve of the human ear in the human hearing characteristic curve, the frequencies of sideband harmonics are mapped to human hearing sensitivity coefficients. The structural modal parameters of the brushless motor are obtained, and the acoustic radiation efficiency is calculated according to the preset brushless motor structural transfer function. Based on the mathematical distribution of the sideband orders at the switching frequency, the human hearing sensitivity coefficients at the harmonic frequencies corresponding to each sideband order are weighted and calculated with the acoustic radiation efficiency output by the structural transfer function to obtain the comprehensive noise sensitivity level corresponding to each sideband order. The comprehensive noise sensitivity level is then associated and stored with the corresponding switching frequency sideband order to obtain an associated database. The associated database includes the noise sensitivity levels corresponding to each sideband order.

[0050] The noise sensitivity level of the current candidate harmonic order is obtained by querying the associated database. If the target noise sensitivity level is greater than the preset sensitivity threshold and the harmonic corresponding to the target noise sensitivity level belongs to the switching frequency modulation sideband, the candidate harmonic is identified as a harmonic of human interest. During the query process, a complementary method of order matching and interval interpolation is adopted so that even if there is a deviation in the order of the candidate harmonic, the corresponding target noise sensitivity level can be accurately obtained. The preset sensitivity threshold is determined by a combination of basic noise benchmark calibration, application scenario classification, and engineering experience correction. Specifically, under the rated operating condition of the motor without noise reduction strategy, the A-weighted sound pressure level of audible noise is collected as the basic benchmark. According to the human hearing comfort threshold (usually 35-45 dB (A)) and industry noise standard requirements, the quietness priority level is divided (e.g., high priority in home appliances, medium priority in industrial equipment). Then, based on the comprehensive noise sensitivity level distribution of each sideband order in the associated database, 70% to 80% of the sensitivity level corresponding to the basic benchmark is taken as the preset sensitivity threshold. For example, a household brushless fan motor has a rated audible noise level of 42 dB(A) without noise reduction. The corresponding comprehensive noise sensitivity level in the associated database is 8 (out of 10). Based on the requirement for extremely quiet operation in a household setting, a sensitivity threshold of 6.4 (8 × 80%) is chosen. When the target noise sensitivity level of a candidate harmonic is greater than 6.4 and belongs to the switching frequency modulation sideband, it is determined to be a harmonic of concern to the human ear. 70% to 80% of this is an empirical coefficient representing engineering compromise.

[0051] As can be seen from the above, this embodiment derives the fundamental frequency by rotating speed and calculates the harmonic order, thereby locating the sideband harmonics generated by the switching frequency modulation and providing a basis for subsequent targeted suppression. By constructing a correlation database based on the human ear hearing characteristic curve, the motor structure transfer function, and the mathematical distribution of the sideband order, a quantitative assessment of noise sensitivity level is achieved, improving the targeting of harmonic screening. Based on database queries and combined with the dual judgment of sensitivity threshold and sideband attributes, the accuracy of anti-screening harmonics of human ear concern is improved, and ineffective suppression is reduced.

[0052] In one embodiment of this application, a correlation database between the switching frequency sideband harmonic order and audible noise is established based on the human ear hearing characteristic curve, the structural transfer function of a brushless motor, and the mathematical distribution of the switching frequency sideband order, including: Based on the human ear A-weighted characteristic curve in the human ear hearing characteristic curve, the frequency of the sideband harmonics is mapped to the human ear hearing sensitivity coefficient. Obtain the structural modal parameters of the brushless motor, and obtain the acoustic radiation efficiency based on the preset structural transfer function of the brushless motor; Based on the mathematical distribution of the sideband orders of the switching frequency, the human hearing sensitivity coefficient at the harmonic frequency corresponding to each sideband order is weighted and calculated with the acoustic radiation efficiency output by the structure transfer function to obtain the comprehensive noise sensitivity level corresponding to each sideband order. The overall noise sensitivity level is associated with the corresponding switching frequency sideband order and stored to obtain an associated database.

[0053] In this embodiment, based on the human ear A-weighted characteristic curve in the human ear hearing characteristic curve, the frequency of sideband harmonics is mapped to the human ear hearing sensitivity coefficient. Specifically, according to the frequency-sensitivity correspondence of the human ear A-weighted characteristic curve, a mapping model between frequency and sensitivity coefficient is established. Sideband harmonics of different frequencies are matched one by one, and the sideband harmonic frequencies of different frequency bands are converted into corresponding quantized sensitivity coefficients. Among them, the sideband harmonics in the human ear sensitive frequency band (1kHz-8kHz) will be mapped to obtain sensitivity coefficients.

[0054] In the structural modal parameter acquisition stage, parameters such as natural frequencies, damping ratios, and mode shapes of core components like the motor stator, housing, and end caps are collected through modal testing experiments (e.g., hammer impact method, vibration method). The pre-defined brushless motor structural transfer function is optimized based on finite element simulation and experimental data fitting to determine the transfer relationship between harmonic excitation frequencies and the motor's structural vibration response and acoustic radiation energy. By substituting sideband harmonic frequencies into the brushless motor structural transfer function, the efficiency of the motor structure in converting vibration energy into sound energy at the corresponding frequencies is obtained, i.e., the acoustic radiation efficiency. Acoustic radiation efficiency refers to the proportion of structural vibration energy converted into audible sound energy into the ambient air at a specific harmonic excitation frequency, characterizing the ease with which the motor structure converts electromagnetic harmonic vibrations into radiated noise. The preset transfer function of the brushless motor structure is: H(w)=G(w) / R(w)·n(w)=F{H(w)}, where w is the frequency of the sideband harmonics, which is the excitation frequency corresponding to each order of sideband harmonics under switching frequency modulation; G(w) is the amplitude of the vibration response generated by the motor stator, housing, and end cover structure after electromagnetic excitation in the frequency domain; H(w) is the preset transfer function of the brushless motor structure, which represents the amplitude transfer ratio from the electromagnetic excitation force of the motor structure to the vibration response of the structure under different harmonic excitation frequencies; R(w) is the amplitude of the electromagnetic excitation force generated by the electromagnetic harmonics in the air gap of the motor in the frequency domain; n(w) is the acoustic radiation efficiency; and F{H(w)} is the acoustic mapping operation.

[0055] Based on the mathematical distribution of the sideband orders at the switching frequency, the human auditory sensitivity coefficient at the harmonic frequencies corresponding to each sideband order is weighted and calculated with respect to the acoustic radiation efficiency output by the structure transfer function to obtain the comprehensive noise sensitivity level for each sideband order. Specifically, in the weighted calculation process, the weighting coefficients are determined according to the actual application scenario and motor characteristics: if the application scenario has extremely high requirements for auditory experience (such as home appliances and precision equipment), the weight of the human auditory sensitivity coefficient is increased; if the motor structure is prone to resonance amplification of noise (thin and light casing design), the weight of the acoustic radiation efficiency is appropriately increased. Through a weighted summation formula, the two quantitative indicators corresponding to the same sideband order are merged into a comprehensive noise sensitivity level, which represents the strength of audible noise caused by sideband harmonics.

[0056] The overall noise sensitivity level is associated with the corresponding switching frequency sideband order, resulting in an associated database. For example, a structured storage method is used, creating a dedicated data entry for each switching frequency sideband order. Each entry includes information such as the sideband order number, corresponding harmonic frequency range, human hearing sensitivity coefficient, sound radiation efficiency, and overall noise sensitivity level. All switching frequency sideband orders are then aggregated to form the associated database. Furthermore, the associated database supports an update mechanism: when the motor application scenario changes, structural parameters are adjusted, or the switching frequency range is modified, the parameters and overall level of the corresponding sideband order can be recalculated, iteratively updating the database content.

[0057] As can be seen from the above, this embodiment maps the hearing sensitivity coefficient according to the human ear A-weighted characteristic curve, which closely matches the actual hearing perception of the human ear, making the harmonic noise assessment consistent with subjective listening. It obtains the motor structure modal parameters and solves the sound radiation efficiency through the structural transfer function, which improves the accuracy of the correlation between harmonics and the acoustic response of the motor structure. Furthermore, it achieves a comprehensive quantification of noise impact by weighting the hearing sensitivity coefficient and sound radiation efficiency according to the mathematical distribution of sideband order. It constructs a database by associating the comprehensive sensitivity level with the sideband order, providing data support for subsequent rapid query and matching.

[0058] In one embodiment of this application, after obtaining the structural modal parameters of the brushless motor and obtaining the acoustic radiation efficiency based on the preset brushless motor structural transfer function, the method further includes: Match the frequency of the sideband harmonics with the frequency sampling points of the structure transfer function; If the frequency of the sideband harmonics aligns with the sampling frequency of the structure transfer function, the corresponding acoustic radiation efficiency can be read directly. If the frequency of the sideband harmonics deviates from the sampling frequency of the structure transfer function, the auditory sensitivity coefficient and sound radiation efficiency at the sampling frequency are interpolated to obtain the final sound radiation efficiency.

[0059] In this embodiment, before matching the frequency of the sideband harmonics with the frequency sampling points of the structure transfer function (STF), the frequency sampling points of the STF need to be normalized to determine the frequency interval and coverage of each sampling point. The sampling points of the STF are distributed according to logarithmic or linear intervals to obtain the frequency range of sideband harmonics that will appear in the brushless motor. By traversing all frequency sampling points of the STF, the frequency of the sideband harmonics is compared with the sampling point frequency one by one to determine whether they are within a preset frequency error allowable range. For example, if the frequency of the sideband harmonics aligns with the sampling frequency point of the STF, i.e., the frequency difference is within the error allowable range, the corresponding acoustic radiation efficiency is directly read. If the frequency of the sideband harmonics deviates from the sampling frequency point of the STF, i.e., the frequency difference exceeds the error allowable range, the auditory sensitivity coefficient and acoustic radiation efficiency of the sampling frequency point are interpolated to obtain the final acoustic radiation efficiency. Before the interpolation process, the two adjacent sampling frequency points closest to the sideband harmonic frequency need to be selected. The interpolation method employs either linear interpolation or cubic spline interpolation. Specifically, linear interpolation is suitable for scenarios with high sampling point density and small frequency intervals, offering high computational efficiency and meeting basic accuracy requirements. Cubic spline interpolation, on the other hand, is suitable for cases with larger sampling point intervals. By constructing a smooth interpolation curve, it effectively avoids the abrupt accuracy changes that may occur with linear interpolation, more accurately restoring the nonlinear relationship between frequency changes and sound radiation efficiency and auditory sensitivity coefficient. The preset allowable frequency error range is determined by comprehensively calibrating the brushless motor's sideband harmonic frequency fluctuation characteristics, the frequency sampling point interval of the structural transfer function, and the interpolation accuracy. Specifically, firstly, based on the linear or logarithmic interval of the frequency sampling points after normalization of the structural transfer function, half the distance between two adjacent frequency sampling points is used as the basic error limit. Then, corrections are made based on the sideband harmonic frequency drift caused by speed fluctuations and bus voltage disturbances during actual motor operation. Finally, the allowable frequency error range is obtained by weighting the three factors based on the accuracy of linear interpolation and cubic spline interpolation.

[0060] During the interpolation calculation, the auditory sensitivity coefficient and the sound radiation efficiency are simultaneously coupled and interpolated. Finally, the final sound radiation efficiency is obtained through the interpolation method. The final sound radiation efficiency is the true quantified efficiency value of the noise radiated from the motor structure to the outside at the actual excitation frequency of the corresponding sideband harmonic.

[0061] As can be seen from the above, this embodiment, by matching the sideband harmonic frequency with the sampling points of the structural transfer function, not only takes into account the computational efficiency, but also ensures the completeness and accuracy of the acoustic radiation efficiency acquisition across the entire frequency range, further improving the accuracy of target characteristic harmonic screening and ensuring the pertinence and effectiveness of the noise reduction and vibration suppression strategy.

[0062] In one embodiment of this application, a random carrier frequency is obtained by changing the carrier frequency with a pseudo-random sequence within a preset switching period, including: The bus voltage data is mapped using a voltage-frequency mapping relationship to obtain the carrier frequency reference value; The carrier frequency of the current switching cycle is obtained by multiplying the random number generated by the pseudo-random number generator within the current switching cycle with the carrier frequency reference value. The pulse width modulation timer period value is updated based on the initial random carrier frequency of the current switching cycle to obtain the random carrier frequency that changes cycle by cycle.

[0063] In this embodiment, the bus voltage often experiences dynamic changes during actual motor operation, such as grid fluctuations, sudden load changes, and battery voltage drops. If the carrier frequency remains fixed, it will cause modulation over-modulation, voltage waveform distortion, and increased harmonic noise. The bus voltage data is used as an input variable in the voltage-frequency mapping relationship, which is obtained by piecewise linear fitting or table lookup fitting. The carrier frequency reference value is calculated based on the real-time bus voltage through the voltage-frequency mapping relationship and serves as the frequency for random carrier frequency modulation.

[0064] The pseudo-random number generator outputs normalized random numbers within a defined range in real time during each switching cycle according to preset generation rules. The carrier frequency for the current switching cycle is obtained by multiplying the pseudo-random numbers with a carrier frequency reference value. The preset generation rules refer to a complete set of rules that pre-define the initial seed value, numerical generation range constraints, sequence iterative algorithm, and periodic update logic of the pseudo-random number generator. Specifically, these rules include limiting the normalized random numbers output in each switching cycle to a fixed numerical range, using a linear congruent or shift register-type pseudo-random recursive algorithm for sequence iteration, and using historical carrier frequency sequences and bus voltage fluctuations as disturbance correction conditions to constrain the range, uniformity, and iteration step size of the random numbers.

[0065] In this embodiment, the controller uses the switching cycle as the smallest time scheduling unit. At the beginning of each cycle, it reads the random carrier frequency of the current switching cycle and updates the internal timer cycle value of the pulse width modulation according to the conversion relationship between frequency and timer counting cycle. As the timer cycle value is dynamically rewritten cycle by cycle, the oscillation period of the carrier triangular wave changes synchronously, so that the carrier frequency no longer remains in a fixed constant state, but forms a random carrier frequency that jumps irregularly cycle by cycle.

[0066] As can be seen from the above, this embodiment determines the carrier frequency reference value based on the voltage-frequency mapping relationship of the bus voltage, which can adapt to the bus voltage fluctuation condition and allow the carrier reference to adjust adaptively with the voltage, which is more in line with the actual operating condition of the motor. The carrier frequency of a single switch cycle is solved by multiplying the pseudo-random number with the carrier frequency reference value to realize randomized modulation of the carrier frequency. The timer period is updated in real time according to the random carrier frequency to form a random carrier that changes dynamically cycle by cycle, which weakens the sharp howling and adapts to voltage disturbance changes, further improving the stability of the pulse width modulation of the high-speed brushless motor, and effectively suppressing electromagnetic noise and vibration at the sound source level.

[0067] In one embodiment of this application, after updating the timer period value of the pulse width modulation according to the initial random carrier frequency of the current switching period to obtain the periodically changing random carrier frequency, the method further includes: The generation status of the pseudo-random sequence is updated in real time, and the seed value of the pseudo-random number generator in the current switching cycle is adjusted according to the carrier frequency of the previous switching cycle. The frequency difference between the random carrier frequency generated in the current switching cycle and the carrier frequency in the adjacent switching cycle is constrained to obtain the constrained carrier frequency. The historical sequence of carrier frequencies during the switching cycle is used as the perturbation input for the next round of pseudo-random sequence generation to update the seed value of the pseudo-random number generator and obtain the target seed value. When fluctuations in the bus voltage data are detected, the update step size of the pseudo-random sequence is adjusted to obtain the rate of change of the random carrier frequency. The random carrier frequency change rate is superimposed with the constrained carrier frequency to obtain the final random carrier frequency.

[0068] In this embodiment, during each switching cycle, the generation status of the pseudo-random sequence is tracked and recorded, and the sequence iteration progress and output distribution characteristics are updated. Simultaneously, based on the historical frequency correlation mechanism, the carrier frequency of the previous switching cycle is used as a feedback correction amount to adjust the seed value of the pseudo-random number generator in the current switching cycle, ensuring correlation and staggered distribution of random number outputs between cycles. Specifically, within each switching cycle, the actual carrier frequency output of the previous switching cycle is used as the frequency feedback correction amount. This frequency feedback correction amount is weighted and fused with the preset frequency range and distribution constraints of the current cycle to obtain the corrected value, which is then assigned as the seed value of the pseudo-random number generator for the current cycle.

[0069] The constrained carrier frequency is obtained by constraining the frequency difference between the random carrier frequency generated in the current switching cycle and the carrier frequency of the adjacent switching cycle. The difference between the random carrier frequency generated in the current switching cycle and the carrier frequency of the adjacent switching cycle is compared. If the frequency difference is greater than a preset limit, a smoothing and limiting correction is performed according to a defined slope. If the frequency difference is less than or equal to the preset limit, it is within the allowable range, and the original frequency value is directly retained. The frequency difference constraint mechanism suppresses drastic frequency jumps, ultimately yielding the constrained carrier frequency. The preset limit is a pre-set maximum allowable frequency difference threshold between the carrier frequencies of adjacent switching cycles, used to limit the amplitude of the random carrier frequency jumps cycle by cycle. This limit is set based on the brushless motor operating conditions, the modulation characteristics of the power switching devices, and the requirements for motor operation smoothness and electromagnetic noise reduction.

[0070] In this embodiment, the historical carrier frequency sequence of the switching cycle is used as the perturbation input for the next round of pseudo-random sequence generation, updating the seed value of the pseudo-random number generator to obtain the target seed value. The historical carrier frequency sequences of multiple switching cycles are cached and integrated into a single historical sequence, which is then used as an external perturbation variable in the pseudo-random number generation logic. The seed value of the pseudo-random number generator is iteratively updated using the temporal variation characteristics of the historical carrier frequency sequence, further disrupting the sequence output pattern and weakening the correlation of fixed periods. After iterative correction, a target seed value adapted to the current brushless motor operating conditions is formed.

[0071] When fluctuations in the bus voltage data are detected, the update step size of the pseudo-random sequence is adjusted to obtain the random carrier frequency change rate. The controller monitors the fluctuation amplitude and rate of change of the bus voltage data and identifies abnormal fluctuations such as voltage spikes, drops, and slow drifts. Once an abnormal fluctuation in the bus voltage data is determined, the update step size of the pseudo-random sequence is adjusted. The update step size includes the iteration of pseudo-random numbers and the value span, which is then linearly converted to obtain the corresponding random carrier frequency change rate. For example, the adjustment is based on the fluctuation amplitude and rate of change of the bus voltage, and abnormal fluctuation types such as voltage spikes, drops, and slow drifts are identified; the iteration speed and value span of the pseudo-random sequence are dynamically adjusted according to the strength of the voltage fluctuation. The random carrier frequency change rate is superimposed with the constrained carrier frequency to obtain the final random carrier frequency.

[0072] As can be seen from the above, this embodiment reduces the periodic repetition of the random sequence by updating the pseudo-random sequence state in real time and adjusting the random number seed based on the preceding carrier frequency; it suppresses the additional vibration and electromagnetic shock caused by excessive frequency jumps by constraining the frequency difference of the carrier frequencies of adjacent switching cycles; it improves the disorder and noise dispersion effect of the random carrier by optimizing the seed value based on the historical sequence of carrier frequencies as a disturbance input; it detects bus voltage fluctuations and adaptively adjusts the update step size of the pseudo-random sequence to match the voltage disturbance and generate a reasonable carrier frequency change rate; and it then superimposes the frequency difference constraint to obtain the final carrier frequency. This ensures that the randomization of the pulse width modulation carrier disperses the switching howling noise while limiting frequency abrupt changes and adapting to bus voltage fluctuations, thus effectively suppressing electromagnetic noise while ensuring the stable and reliable operation of the motor.

[0073] In one embodiment of this application, after generating the dual-strategy cooperative driving command based on the target fundamental current command and the pulse width modulation control command, the method further includes: Acquire real-time noise signals during motor operation; Spectral analysis of real-time noise signals is performed. The suppression effect of reverse harmonic current injection on discrete characteristic harmonics is taken as the first suppression effect, and the suppression effect of pulse width modulation on sideband harmonics is taken as the second suppression effect. Based on the first and second suppression effects, adjust the participation weights of the target fundamental current command and pulse width modulation control command in the joint control: When the first suppression effect is less than the preset ideal suppression index, increase the amplitude coefficient of the reverse harmonic injection; when the second suppression effect is less than the preset ideal suppression index, increase the carrier frequency variation range of random pulse width modulation. When both the first and second suppression effects are less than the preset ideal suppression index and interfere with each other, a time-division multiplexing method is adopted to divide the control cycle into alternating time segments. In the first time segment, reverse harmonic current injection is executed separately, and in the second time segment, random pulse width modulation strategy is executed separately. The length ratio of the two time segments is adjusted according to the historical suppression effect.

[0074] In this embodiment, firstly, acoustic sensors and vibration acceleration sensors are arranged on the motor housing, stator surface, or the whole machine to collect real-time noise signals during the operation of the motor at high speed.

[0075] Secondly, a windowed Fourier transform is used to perform spectral analysis on the real-time noise signal, decomposing the noise energy distribution across the entire frequency band, locating the noise amplitude at the frequency corresponding to the discrete characteristic harmonics, and the noise peak value corresponding to the sideband harmonics at the switching frequency. By comparing the noise attenuation and vibration amplitude attenuation at the same frequency before and after the implementation of the noise reduction strategy, the degree of weakening of the target discrete characteristic harmonics by the reverse harmonic current injection is quantitatively evaluated, which serves as the first suppression effect. At the same time, the overall energy diffusion and amplitude reduction level of the sideband harmonics at the switching frequency are statistically analyzed, and the smoothing and scattering suppression capability of pulse width modulation on the sideband harmonics is quantitatively evaluated, which serves as the second suppression effect.

[0076] Subsequently, the first and second suppression effects are compared with preset ideal suppression indicators to obtain their respective performance levels. Based on these performance levels, the participation weights of the target fundamental current command and pulse width modulation control command in the dual-strategy joint control are dynamically allocated. The weight allocation method is as follows: the better the performance (the higher the performance level), the more appropriately the corresponding strategy weight is maintained; the weaker the performance, the more appropriately the control proportion of the corresponding strategy is increased. For example, if the first suppression effect is less than the preset ideal suppression indicator, it indicates that the current reverse harmonic compensation is insufficient. The cancellation depth of discrete characteristic harmonics is improved by correspondingly increasing the amplitude coefficient of the reverse harmonic injection. If the second suppression effect is less than the preset ideal suppression indicator, it indicates that the existing random frequency modulation range is insufficient to fully disperse sideband harmonic energy. The frequency random disturbance range is widened by correspondingly increasing the carrier frequency variation range of random pulse width modulation. Among them, the preset ideal suppression index is the standard suppression and attenuation threshold that discrete characteristic harmonics and switching sideband harmonics are expected to achieve in terms of amplitude, noise energy, and vibration amplitude, which is calibrated and solidified in advance through simulation and prototype testing. The preset ideal suppression index is determined by a comprehensive compromise based on the theoretical calculation of motor harmonic acoustic simulation, the actual measurement of whole machine noise and vibration prototype, and the integration of motor operating loss, temperature rise, and operating condition stability constraints.

[0077] When both the first and second suppression effects are less than the preset ideal suppression index and interfere with each other, it indicates a situation where control coupling conflicts and mutual cancellation occur when both control strategies are applied simultaneously, leading to overall noise reduction failure. In this situation, time-division multiplexing is adopted. Specifically, the control cycle is divided into alternating independent time segments in the time dimension, and control strategies are isolated. In the first time segment, only reverse harmonic current injection is applied to focus on canceling discrete characteristic harmonics and structural resonance noise. In the second time segment, only random pulse width modulation strategy is used to specifically disperse the switching sideband harmonic energy, thus avoiding mutual interference in timing. At the same time, based on the stored historical suppression effect data, the length ratio of the two time segments is continuously iteratively optimized, allowing the time segment with better noise reduction effect to be allocated a longer running time.

[0078] As can be seen from the above, this embodiment, by acquiring real-time noise signals from the motor and performing spectrum analysis, can quantitatively evaluate the noise reduction effects of two types: reverse harmonic injection to suppress discrete characteristic harmonics and random pulse width modulation to suppress switching sideband harmonics. The participation weights of the dual control strategies are adjusted based on the two suppression effects. When the two control strategies interfere with each other and the noise reduction effect is not as expected, time-division multiplexing is used to split the control cycle and execute the two noise reduction strategies independently in a time-division manner. This technology achieves online monitoring and closed-loop self-tuning of the noise reduction effect, reduces multi-strategy coupling interference, and further improves the quietness and control stability of the high-speed brushless motor under all operating conditions.

[0079] In one embodiment of this application, the length ratio of the two time segments is adjusted according to the historical suppression effect, including: At the end of each time segment, the A-weighted sound pressure level of the noise signal within each time segment is calculated. The A-weighted sound pressure level in the first time segment is recorded as the first noise index, and the A-weighted sound pressure level in the second time segment is recorded as the second noise index. The ratio of the first noise index to the second noise index is taken as the noise suppression ratio. When the noise suppression ratio is greater than 1, the length of the first time segment is increased by a preset first step length, and the length of the second time segment is decreased by increasing the first step length. When the noise suppression ratio is less than 1, the length of the first time segment is reduced by the first step length, and the length of the second time segment is increased by the first step length; the total length of the two time segments remains unchanged, and the minimum length of a single time segment is not less than a complete current control cycle.

[0080] In this embodiment, at the end of each time segment, a complete data segment of the continuously collected noise signal is extracted, and weighted filtering is performed according to the human hearing A-weighting standard to remove interference components of low-sound frequency band, infrasound frequency band, and irrelevant environmental noise; the steady-state effective sound pressure level in the time segment is calculated by the sound pressure level conversion algorithm.

[0081] The sound pressure level value corresponding to the first time segment is labeled as the first noise index, and the sound pressure level value corresponding to the second time segment is labeled as the second noise index. Both indices use a unified calculation standard, sampling duration, and frequency weighting rule, ensuring they have comparable benchmarks. Numerical calculations are performed using the first noise index as the numerator and the second noise index as the denominator to obtain a dimensionless ratio, which is defined as the noise suppression ratio. The noise suppression ratio characterizes the noise reduction performance of the two time-division multiplexing control strategies, and the ratio represents the relative strength of the noise reduction effect between the first and second time segments.

[0082] For example, a noise suppression ratio greater than 1 indicates a higher first noise index value, corresponding to a better noise reduction effect and lower noise level in the first time segment. In this case, based on the preset first step length, the time segment ratio is adjusted, simultaneously increasing the length of the first time segment and decreasing the length of the second time segment, allowing the control strategy with better noise reduction to have a longer execution time share. A noise suppression ratio less than 1 indicates a better performance in the second noise index, with the control strategy corresponding to the second time segment showing a more prominent noise reduction effect. In this case, based on the preset first step length, the length of the first time segment is simultaneously decreased and the length of the second time segment is increased, achieving a time resource allocation tilted towards the better strategy. Throughout the entire adjustment process, the total length of the two time segments remains constant. The preset first step length is calculated by dividing the total duration of the time-division multiplexing switching cycle by the preset number of adjustment levels. The formula is: the first step length for a single adjustment equals the total time-division multiplexing duration divided by the preset number of adjustment levels. This first step length is a fixed time increment. Each adjustment is made by increasing or decreasing the first step length based on the noise suppression ratio of the two time segments. During the adjustment process, the total length of the two time segments remains constant, and the minimum length of a single time segment is limited to be greater than or equal to one switching cycle. The preset number of adjustment levels is set comprehensively based on the motor control response speed, the smoothness of the time ratio adjustment, and the control accuracy requirements.

[0083] As can be seen from the above, this embodiment calculates the A-weighted sound pressure level of noise after each time segment to obtain the noise reduction level characterizing the two time-division control strategies; it constructs the noise suppression ratio based on the ratio of the two sound pressure levels, adjusts the duration of the two time segments, and keeps the total control cycle unchanged. This achieves adaptive self-tuning of the time-division multiplexing time ratio, reduces subjective debugging errors, ensures the integrity of the current control timing and operational stability, and can optimally allocate the working duration of the two noise reduction strategies, thus improving the overall noise reduction and vibration suppression effect.

[0084] Corresponding to the electromagnetic noise reduction and vibration suppression method for high-speed brushless motors in the above embodiments, Figure 2 This is a structural block diagram of a high-speed brushless motor electromagnetic noise reduction and vibration suppression system according to an embodiment of this application. For ease of explanation, only the parts relevant to the embodiment of this application are shown. References Figure 2 The high-speed brushless motor electromagnetic noise reduction and vibration suppression system 20 includes: a multi-source data acquisition module 21, a speed load determination module 22, a coordinate transformation extraction module 23, a reverse harmonic generation module 24, a random carrier frequency modulation module 25, and a cooperative drive control module 26.

[0085] Among them, the multi-source data acquisition module 21 is used to collect the three-phase current data, rotor position data and bus voltage data of the brushless motor; The speed and load determination module 22 is used to determine the speed based on the rotor position data and the load current based on the three-phase current data. The coordinate transformation extraction module 23 is used to perform coordinate transformation on the three-phase current data, convert it to a synchronous rotating coordinate system, and extract the fundamental current component when the rotational speed is greater than or equal to a preset rotational speed threshold and the negative current corresponding to the load current is within a preset current range. The reverse harmonic generation module 24 is used to determine the target characteristic harmonic related to electromagnetic noise based on the fundamental current component, and extract the amplitude and phase of the target characteristic harmonic; based on the amplitude and phase of the target characteristic harmonic, generate a reverse harmonic current with the same amplitude and opposite phase as the target characteristic harmonic; and generate a target fundamental current command based on the superposition of the reverse harmonic current and the fundamental current. The random carrier frequency modulation module 25 is used to change the carrier frequency with a pseudo-random sequence within a preset switching period to obtain a random carrier frequency and generate a pulse width modulation control command. The collaborative drive control module 26 is used to generate dual-strategy collaborative drive instructions based on the target fundamental current command and the pulse width modulation control command, and to perform noise reduction and vibration suppression processing on the brushless motor based on the dual-strategy collaborative drive instructions.

[0086] See Figure 3 , Figure 3 This is a schematic block diagram of an electronic device provided according to an embodiment of this application. Figure 3 The electronic device 300 in this embodiment may include one or more processors 301, one or more input devices 302, one or more output devices 303, and one or more memories 304. The processors 301, input devices 302, output devices 303, and memories 304 communicate with each other via a communication bus 305. The memories 304 store computer programs, including program instructions. The processors 301 execute the program instructions stored in the memories 304. Specifically, the processors 301 are configured to invoke the program instructions to perform the functions of the modules in the aforementioned device embodiments, for example... Figure 2 The functions of the multi-source data acquisition module 21, speed and load determination module 22, coordinate transformation extraction module 23, reverse harmonic generation module 24, random carrier frequency modulation module 25, and cooperative drive control module 26 are shown.

[0087] It should be understood that, in the embodiments of this application, the processor 301 may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0088] Input device 302 may include a touchpad, a fingerprint sensor (for collecting the user's fingerprint information and fingerprint orientation information), a microphone, etc., and output device 303 may include a display (LCD, etc.), a speaker, etc.

[0089] The memory 304 may include read-only memory and random access memory, and provides instructions and data to the processor 301. A portion of the memory 304 may also include non-volatile random access memory. For example, the memory 304 may also store device type information.

[0090] In specific implementations, the processor 301, input device 302, and output device 303 described in the embodiments of this application can execute the implementation methods described in any embodiment of the electromagnetic noise reduction and vibration suppression method for high-speed brushless motors provided in the embodiments of this application, or they can execute the implementation methods of the electronic devices described in the embodiments of this application, which will not be repeated here.

[0091] In another embodiment of this application, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program, which includes program instructions. When executed by a processor, the program instructions implement all or part of the processes in the methods described above. Alternatively, the computer program can instruct related hardware to complete the process. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0092] The computer-readable storage medium can be an internal storage unit of the electronic device in any of the foregoing embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium can also be an external storage device of the electronic device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on the electronic device. Furthermore, the computer-readable storage medium can include both internal and external storage units of the electronic device. The computer-readable storage medium is used to store computer programs and other programs and data required by the electronic device. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0093] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0094] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the electronic devices and units described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0095] In the several embodiments provided in this application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces or units, or it may be an electrical, mechanical, or other form of connection.

[0096] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of this application, depending on actual needs.

[0097] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0098] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor, characterized in that, include: Collect three-phase current data, rotor position data, and bus voltage data of the brushless motor; Based on the rotor position data, the rotational speed is determined; based on the three-phase current data, the load current is determined. When the rotational speed is greater than or equal to a preset rotational speed threshold and the negative current corresponding to the load current is within a preset current range, the three-phase current data is transformed into a synchronous rotating coordinate system, and the fundamental current component is extracted. Based on the fundamental current component, the target characteristic harmonics related to electromagnetic noise are determined, and the amplitude and phase of the target characteristic harmonics are extracted. Based on the amplitude and phase of the target characteristic harmonic, a reverse harmonic current with the same amplitude but opposite phase to the target characteristic harmonic is generated. The reverse harmonic current is superimposed on the fundamental current to generate a target fundamental current command. Within a preset switching cycle, the carrier frequency is changed using a pseudo-random sequence to obtain a random carrier frequency, and a pulse width modulation control command is generated. Based on the target fundamental current command and the pulse width modulation control command, a dual-strategy collaborative drive command is generated, and noise reduction and vibration suppression processing are performed on the brushless motor based on the dual-strategy collaborative drive command.

2. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 1, characterized in that, The step of determining the target characteristic harmonics related to electromagnetic noise based on the fundamental current component includes: Spectral analysis was performed on the fundamental current component to obtain current harmonics of different frequencies; Extract the amplitude of the current harmonics, and select the current harmonics with amplitudes greater than a preset harmonic current threshold as candidate harmonics; Based on the correlation database between the candidate harmonics and the preset switching frequency sideband harmonic order and audible noise, the harmonics of interest to the human ear are obtained. Harmonics associated with the resonant frequency of the motor structure are selected from the harmonics that are of interest to the human ear and identified as structural resonant harmonics. The target characteristic harmonic is determined by the structural resonance harmonic that simultaneously satisfies the requirements of the frequency band sensitive to human hearing and is associated with the resonant frequency of the motor structure.

3. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 2, characterized in that, The association database based on the rotor position data and the preset switching frequency sideband harmonic order and audible noise yields harmonics of interest to the human ear, including: The fundamental frequency is obtained by substituting the rotational speed corresponding to the candidate harmonic into the fundamental frequency formula. The order of the candidate harmonic is obtained by dividing the frequency of the current harmonic by the fundamental frequency. The order of the candidate harmonic is analyzed, and the sideband harmonic generated by the switching frequency modulation is determined. The order corresponding to the sideband harmonic is taken as the sideband order of the switching frequency. Based on the human hearing characteristic curve, the preset brushless motor structure transfer function, and the mathematical distribution of the switching frequency sideband order, a correlation database is established between the switching frequency sideband harmonic order and audible noise. The correlation database includes the noise sensitivity level corresponding to each sideband order. Based on the association database, the noise sensitivity level of the current candidate harmonic order is queried to obtain the target noise sensitivity level. If the target noise sensitivity level is greater than the preset sensitivity threshold and the harmonic corresponding to the target noise sensitivity level belongs to the switching frequency modulation sideband, then the candidate harmonic is determined to be a harmonic of human ear interest.

4. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 3, characterized in that, The database establishing the correlation between the switching frequency sideband harmonic order and audible noise based on the human ear hearing characteristic curve, the structural transfer function of the brushless motor, and the mathematical distribution of the switching frequency sideband order includes: Based on the human ear A-weighted characteristic curve in the human ear hearing characteristic curve, the frequency of the sideband harmonics is mapped to the human ear hearing sensitivity coefficient; Obtain the structural modal parameters of the brushless motor, and obtain the acoustic radiation efficiency based on the preset structural transfer function of the brushless motor; Based on the mathematical distribution of the switching frequency sideband order, the human hearing sensitivity coefficient at the harmonic frequency corresponding to each sideband order is weighted and calculated with the acoustic radiation efficiency output by the structure transfer function to obtain the comprehensive noise sensitivity level corresponding to each sideband order. The overall noise sensitivity level is associated with the corresponding switching frequency sideband order and stored to obtain the associated database.

5. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 4, characterized in that, After obtaining the structural modal parameters of the brushless motor and calculating the acoustic radiation efficiency based on the preset brushless motor structural transfer function, the method further includes: The frequency of the sideband harmonics is matched with the frequency sampling points of the structure transfer function; If the frequency of the sideband harmonics is aligned with the sampling frequency of the structural transfer function, the corresponding acoustic radiation efficiency is directly read. If the frequency of the sideband harmonics deviates from the sampling frequency of the structure transfer function, the auditory sensitivity coefficient and sound radiation efficiency at the sampling frequency are interpolated to obtain the final sound radiation efficiency.

6. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 1, characterized in that, The step of changing the carrier frequency with a pseudo-random sequence within a preset switching period to obtain a random carrier frequency includes: The bus voltage data is mapped using a voltage-frequency mapping relationship to obtain a carrier frequency reference value; The carrier frequency of the current switching cycle is obtained by multiplying the random number generated by the pseudo-random number generator within the current switching cycle with the carrier frequency reference value. The pulse width modulation timer period value is updated based on the initial random carrier frequency of the current switching cycle to obtain the random carrier frequency that changes cycle by cycle.

7. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 6, characterized in that, After updating the timer period value of the pulse width modulation according to the initial random carrier frequency of the current switching period to obtain the periodically changing random carrier frequency, the method further includes: The generation status of the pseudo-random sequence is updated in real time, and the seed value of the pseudo-random number generator in the current switching cycle is adjusted according to the carrier frequency of the previous switching cycle. The frequency difference between the random carrier frequency generated in the current switching cycle and the carrier frequency in the adjacent switching cycle is constrained to obtain the constrained carrier frequency. The historical sequence of carrier frequency during the switching period is used as the perturbation input for the next round of pseudo-random sequence generation to update the seed value of the pseudo-random number generator and obtain the target seed value. When fluctuations in the bus voltage data are detected, the update step size of the pseudo-random sequence is adjusted to obtain the rate of change of the random carrier frequency. The random carrier frequency change rate is superimposed with the constrained carrier frequency to obtain the final random carrier frequency.

8. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 2, characterized in that, After generating the dual-strategy cooperative driving command based on the target fundamental current command and the pulse width modulation control command, the method further includes: Acquire real-time noise signals during motor operation; Spectral analysis is performed on the real-time noise signal. The suppression effect of reverse harmonic current injection on discrete characteristic harmonics is taken as the first suppression effect, and the suppression effect of pulse width modulation on sideband harmonics is taken as the second suppression effect. Based on the first suppression effect and the second suppression effect, adjust the participation weights of the target fundamental current command and the pulse width modulation control command in the joint control: When the first suppression effect is less than the preset ideal suppression index, the amplitude coefficient of the reverse harmonic injection is increased; when the second suppression effect is less than the preset ideal suppression index, the carrier frequency variation range of random pulse width modulation is increased. When both the first suppression effect and the second suppression effect are less than the preset ideal suppression index and interfere with each other, a time-division multiplexing method is adopted to divide the control cycle into alternating time segments. In the first time segment, reverse harmonic current injection is executed separately, and in the second time segment, random pulse width modulation strategy is executed separately. The length ratio of the two time segments is adjusted according to the historical suppression effect.

9. The method for electromagnetic noise reduction and vibration suppression of a high-speed brushless motor according to claim 8, characterized in that, The length ratio of the two time segments is adjusted according to the historical suppression effect, including: At the end of each time segment, the A-weighted sound pressure level of the noise signal within each time segment is calculated. The A-weighted sound pressure level in the first time segment is recorded as the first noise index, and the A-weighted sound pressure level in the second time segment is recorded as the second noise index. The ratio of the first noise index to the second noise index is taken as the noise suppression ratio; When the noise suppression ratio is greater than 1, the length of the first time segment is increased by a preset first step length, and the length of the second time segment is decreased by the first step length. When the noise suppression ratio is less than 1, the length of the first time segment is reduced by the first step length, and the length of the second time segment is increased by the first step length; wherein the total length of the two time segments remains unchanged, and the minimum length of a single time segment is not less than a complete current control cycle.

10. A high-speed brushless motor electromagnetic noise reduction and vibration suppression system, characterized in that, include: The multi-source data acquisition module is used to collect three-phase current data, rotor position data, and bus voltage data of the brushless motor. The speed-load determination module is used to determine the speed based on the rotor position data and the load current based on the three-phase current data. The coordinate transformation extraction module is used to perform coordinate transformation on the three-phase current data, convert it to a synchronous rotating coordinate system, and extract the fundamental current component when the rotational speed is greater than or equal to a preset rotational speed threshold and the negative current corresponding to the load current is within a preset current range. The reverse harmonic generation module is used to determine the target characteristic harmonics related to electromagnetic noise based on the fundamental current component, and to extract the amplitude and phase of the target characteristic harmonics. Based on the amplitude and phase of the target characteristic harmonic, a reverse harmonic current with the same amplitude but opposite phase to the target characteristic harmonic is generated. The reverse harmonic current is superimposed on the fundamental current to generate a target fundamental current command. The random carrier frequency modulation module is used to change the carrier frequency with a pseudo-random sequence within a preset switching period to obtain a random carrier frequency and generate pulse width modulation control commands. The collaborative drive control module is used to generate a dual-strategy collaborative drive command based on the target fundamental current command and the pulse width modulation control command, and to perform noise reduction and vibration suppression processing on the brushless motor based on the dual-strategy collaborative drive command.

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