Magnetic levitation fan variable frequency drive device and harmonic suppression method

Abstract

The application belongs to the technical field of electric machines, and discloses a magnetic suspension fan variable frequency driving device and a harmonic suppression method; the method comprises the following steps: judging a transient operation process and activating a phase compensation mechanism by monitoring the state of the electric machine in real time, extracting harmonic components in real time and updating a weight vector to obtain harmonic currents of different orders; meanwhile, a phase compensation amount is dynamically obtained based on a pre-built control loop phase lag atlas, an anti-phase harmonic voltage is calculated in combination with the harmonic currents and the compensation phase, and the variable frequency device is injected through a space vector pulse width modulation method to realize accurate harmonic cancellation; torque safety monitoring is also independently operated in parallel in the whole process, the electromagnetic torque and its change rate are detected in real time to perform safety logic determination, and a protection action is triggered when the limit is exceeded; the application can realize accurate cancellation of anti-phase harmonics and actual interference harmonics in the transient process, significantly reduce the instantaneous impact of the electromagnetic torque, and effectively improve the operation stability and reliability of the magnetic suspension fan variable frequency driving system under transient working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, and more particularly, to a magnetic suspension fan variable frequency drive device and a harmonic suppression method. BACKGROUND

[0002] Permanent magnet synchronous motors have been widely used in many fields such as magnetic suspension fans, industrial drones, electric vehicles, etc. due to their high power density and high efficiency. The magnetic suspension fan is a core power component of a high-speed permanent magnet synchronous motor, and relies on the non-contact support of the magnetic suspension bearing to achieve low consumption and low noise operation. However, the stability of the electromagnetic torque is extremely high, and even a small torque fluctuation can affect the rotor suspension stability and even cause vibration failure.

[0003] Chinese patent application No. CN118677308A discloses a permanent magnet synchronous motor model predictive control method for applying an opposite torque harmonic: seamlessly embedding the harmonic suppression task into the model predictive control framework. The process starts with real-time detection and Fourier analysis of the output torque of the permanent magnet synchronous motor to accurately extract the specific harmonic components that cause torque pulsation. Then, the scheme uses an adaptive linear neuron network to identify the amplitude and phase of these harmonics online, and generates an opposite harmonic torque signal accordingly. In each sampling period of the model predictive control, the opposite harmonic torque is included in the value function as a key performance indicator, and is integrated with the traditional torque, flux linkage tracking error and switching frequency constraint for integrated optimization and solution. Through rolling prediction and optimization of the system behavior in the future several switching periods, the optimal voltage vector that minimizes the value function is finally selected and applied, thereby actively canceling the torque harmonic while driving the motor and achieving the purpose of suppressing torque pulsation.

[0004] Although the above method can meet most scenarios, research and practical application of the above method and prior art have found that the above method and prior art at least have the following defects:

[0005] The above method can effectively suppress harmonics in steady state conditions, but in transient processes such as load mutation and grid voltage drop, the phase response characteristics of the control system will change dramatically, which can easily lead to mismatch of the opposite harmonic injection timing, making it impossible to achieve accurate cancellation and exacerbating the instantaneous impact of the electromagnetic torque.

[0006] In view of this, the present application proposes a magnetic suspension fan variable frequency drive device and a harmonic suppression method to solve the above problems. SUMMARY

[0007] In order to overcome the above-mentioned defects of the prior art and achieve the above-mentioned purpose, the present application provides the following technical solutions: a harmonic suppression method for a magnetic suspension fan variable frequency drive device, comprising:

[0008] The system collects stator three-phase current, stator terminal voltage, and rotor mechanical speed to monitor the motor status and determine whether it has entered a transient operation process. If it has entered a transient operation process, the phase compensation mechanism is activated; otherwise, the system continues to monitor the motor status.

[0009] The three-phase current of the magnetic levitation motor is collected and coordinate transformed to obtain the direct-axis current and quadrature-axis current. Harmonics in the direct-axis and quadrature-axis currents are modeled to obtain harmonic components. These harmonic components are extracted to obtain the input vector and network weight vector. Based on the input vector, the weights in the weight vector are updated using the normalized least mean square algorithm to obtain the updated weight vector. The nth... Subharmonic current;

[0010] Construct a phase lag diagram of the control loop; monitor and determine the system status in real time, obtain the phase compensation amount based on the phase lag diagram of the control loop, and obtain the compensation phase;

[0011] According to the The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics.

[0012] Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions.

[0013] Furthermore, methods for constructing the phase lag spectrum of the control loop include:

[0014] The phase lag under static and dynamic operating conditions was simulated and analyzed respectively.

[0015] The operating data and corresponding phase lag values ​​are stored in tabular form to obtain the phase lag spectrum of the control loop.

[0016] Furthermore, methods for simulating and analyzing phase lag under static operating conditions include:

[0017] Step 1: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage and maintain the rated voltage change rate. Below the rate of change threshold;

[0018] Step 2: The controller sends a direct-axis voltage command to the inverter, which is then superimposed with the first... The harmonic voltage is obtained by generating a harmonic voltage command; the harmonic voltage command is continuously output for a duration of not less than L harmonic cycles.

[0019] Step 3: Simultaneously acquire the direct-axis harmonic current and the harmonic voltage command output by the controller, and perform FFT analysis to extract the first harmonic current. The phase of the subharmonic is calculated to obtain the static phase lag; the measurement is repeated K times, and the average value of the K static phase lags is taken as the corresponding phase lag amount;

[0020] Step 4, Keep If the load rate is 0, the load rate is switched sequentially from the target load value according to the first load gradient, and the motor speed is switched sequentially from the target speed according to the first speed gradient. At each load rate and at each speed, a preset sequence of harmonic signals is injected sequentially. Steps 2-3 are repeated to obtain all static operating condition data and the corresponding phase lag.

[0021] Furthermore, methods for simulating and analyzing phase lag under dynamic operating conditions include:

[0022] Step A: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage, and measure the rate of change of the output rated voltage. Once the current falls below the rate of change threshold, it is recorded as the fundamental current.

[0023] Step B: Send a voltage drop command to the programmable AC power supply to control the output of the programmable AC power supply to drop from the rated voltage to the target voltage within a preset time period; at the same time, the controller injects a harmonic voltage command of preset duration into the direct axis.

[0024] Step C: Acquire fundamental voltage, harmonic voltage commands, and voltage sag waveform data; extract transient data within the second preset time period after the voltage sag occurs, divide the transient data into preset time windows, and calculate the voltage sag waveform within each time window. Phase difference of subharmonics; take the maximum value of phase difference within each time window as the corresponding transient phase lag;

[0025] Step D: Keep the load torque and speed constant, and switch the voltage drop amplitude from the rated voltage according to the voltage drop load gradient; under each voltage drop amplitude, inject the preset sequence of harmonic signals in sequence, and repeat steps BC.

[0026] Step E: Switch the load rate sequentially from the target load value according to the second load gradient, and then switch the motor speed sequentially from the target speed according to the second speed gradient. Repeat steps A and D at each load rate and at each speed to obtain all dynamic operating condition data and the corresponding phase lag.

[0027] Furthermore, methods for obtaining the compensated phase include:

[0028] Collect the current speed and load torque, and obtain the corresponding current phase lag from the control loop phase lag diagram.

[0029] Furthermore, methods for obtaining PWM signals include:

[0030] The first was obtained from the fundamental frequency electric angular velocity. The electric angular velocity of the second harmonic is based on the first harmonic. The electric angular velocity of the second harmonic was calculated to obtain the... Subharmonic impedance;

[0031] According to the The original voltage amplitude is obtained by calculating the second harmonic impedance and harmonic current amplitude; based on the first harmonic impedance and harmonic current amplitude... The phase angle of the harmonic impedance is obtained by calculating the phase angle of the harmonic impedance. The initial phase of the subharmonic is calculated to obtain the original voltage phase;

[0032] The compensated voltage phase is calculated based on the total phase compensation and the original voltage phase; the original anti-phase voltage vector is calculated based on the original voltage amplitude and the compensated voltage phase; the original anti-phase voltage vector is decomposed into dq-axis components to obtain anti-phase harmonic voltage components; the anti-phase harmonic voltage components are superimposed with the fundamental dq-axis voltage command to obtain the total voltage command; the total voltage command is converted into a voltage command in a two-phase stationary coordinate system; the voltage command in the two-phase stationary coordinate system is normalized to the DC bus voltage to obtain the normalized voltage vector; The plane is divided into 6 sectors. Based on the sign and amplitude of the voltage command in the two-phase stationary coordinate system, the sector where the normalized voltage vector is located is determined. The action time of the two adjacent effective vectors and the action time of the zero vector in the sector where the normalized voltage vector is located are calculated. Based on the effective vector and zero vector corresponding to the sector where the normalized voltage vector is located, the time is allocated according to the principle of symmetrical modulation. The three-phase duty cycle is used as the input of the controller PWM module to obtain the PWM signal for controlling the IGBT.

[0033] Furthermore, methods for determining the sector containing the normalized voltage vector include:

[0034] Auxiliary variables are obtained by calculating the normalized voltage vector;

[0035] Define a symbolic function and calculate the value of M using auxiliary variables;

[0036] Based on the preset correspondence between M value and sector number, the sector corresponding to the normalized voltage vector is obtained.

[0037] Furthermore, methods for obtaining the input vector and network weight vector include:

[0038] The harmonics in the direct-axis and quadrature-axis currents are uniformly modeled as a harmonic magnetomotive force model; the harmonic magnetomotive force model is expanded using Euler's formula; simplified direct-axis and quadrature-axis harmonic current components are obtained; the sine and cosine terms of each harmonic in the simplified direct-axis and quadrature-axis harmonic current components are extracted to form the input vector; the projections of each harmonic current component on the cosine basis and the projections on the sine basis are extracted to form the network weight vector.

[0039] Furthermore, methods for obtaining the updated weight vector include:

[0040] Based on the direct-axis current reference value or the quadrature-axis current reference value, and the first The actual value of the direct-axis current or the actual value of the quadrature-axis current at the sampling time is used to calculate the first... Error at sampling time; combined with the first Error at sampling time and the first The input vector at the sampling time is used to update the weights in the weight vector based on the normalized least mean square algorithm to obtain the updated weight vector.

[0041] Furthermore, methods for determining whether a transient process has been entered include:

[0042] The electric angular velocity of the motor is calculated based on the rotor's mechanical speed.

[0043] The Clarke transform is used to convert three-phase current into two-phase quiescent current.

[0044] Based on the Park transformation, two-phase stationary currents are converted into two-phase rotating currents to obtain direct-axis currents and quadrature-axis currents.

[0045] The output electromagnetic torque of the motor is calculated based on the direct-axis current, quadrature-axis current, number of motor pole pairs, and permanent magnet flux linkage.

[0046] The rate of change of torque is obtained by statistically analyzing the electromagnetic torque output of the motor.

[0047] The grid voltage drop is calculated based on the stator terminal voltage and the rated line voltage. When the torque change rate is greater than the first torque change rate threshold, or the grid voltage drop is greater than the drop threshold, it is determined that the transient operation process has been entered and the phase compensation mechanism is activated. Otherwise, it is determined that the transient operation process has not been entered.

[0048] Furthermore, the method for determining safety logic based on the motor's output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions, includes:

[0049] After injecting harmonics, the real-time output electromagnetic torque and real-time torque change rate of the motor are analyzed and obtained.

[0050] If the real-time torque change rate is greater than the second torque change rate threshold and the duration exceeds the time threshold, it is determined to be a suppression failure. The weight vector update is immediately stopped, the harmonic voltage command amplitude is exponentially decayed to 0, and the control is switched to pure fundamental PI controller. At the same time, a torque impact alarm signal is output and the fault status is recorded.

[0051] If the suppression is successful, the real-time output electromagnetic torque and real-time torque change rate of the motor will be continuously monitored.

[0052] A magnetic levitation fan frequency converter drive device, comprising a harmonic suppression method for the magnetic levitation fan frequency converter drive device, including:

[0053] Transient detection module: Collects stator three-phase current, stator terminal voltage and rotor mechanical speed, monitors motor status, determines whether it has entered a transient operation process, and activates the phase compensation mechanism when it enters a transient operation process; otherwise, it continues to monitor the motor status.

[0054] The data acquisition and analysis module acquires the three-phase current of the magnetic levitation motor and performs coordinate transformation to obtain the direct-axis current and quadrature-axis current. It models the harmonics in the direct-axis and quadrature-axis currents to obtain harmonic components, extracts these components to obtain the input vector and network weight vector, and updates the weights in the weight vector based on the normalized least mean square algorithm using the input vector to obtain the updated weight vector. Finally, it calculates the first... Subharmonic current;

[0055] Phase compensation module: Constructs a phase lag diagram of the control loop; monitors and judges the system status in real time, obtains the phase compensation amount based on the phase lag diagram of the control loop, and obtains the compensated phase;

[0056] Signal synthesis module: based on the first The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics.

[0057] Monitoring and protection module: Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and trigger corresponding protection actions.

[0058] The technical effects and advantages of the magnetic levitation fan frequency conversion drive device and harmonic suppression method of the present invention are as follows:

[0059] This invention acquires stator three-phase current, stator terminal voltage, and rotor mechanical speed in real time, calculates electromagnetic torque and torque change rate using Clarke / Park transformation, and accurately determines transient operation processes and activates phase compensation mechanisms by combining grid voltage drop. It models direct-axis and quadrature-axis current harmonics as harmonic magnetomotive force models, dynamically updates weight vectors using a normalized least mean square algorithm, and achieves real-time accurate identification of harmonic current amplitude and phase. Based on a pre-constructed phase lag spectrum covering static and dynamic operating conditions, it predicts the total phase compensation amount by combining current speed, load torque, and their change rates, adapting to severe fluctuations in phase response under transient conditions. It also incorporates harmonic impedance... The identified harmonic current and total phase compensation amount are combined to form an anti-phase harmonic voltage, which is superimposed with the fundamental voltage command on the dq axis and converted into a two-phase static voltage command through inverse Park transformation. Then, a precise IGBT drive PWM signal is generated and injected into the frequency converter through the SVPWM algorithm. At the same time, the electromagnetic torque and torque change rate are monitored in real time. If the suppression is determined to be ineffective, the weight update is immediately frozen, the harmonic voltage command is exponentially decayed to zero, and the control is switched to pure fundamental PI control. In the end, the anti-phase harmonic and the actual interference harmonic are accurately canceled during the transient process, which significantly reduces the instantaneous impact of electromagnetic torque and effectively improves the operating stability and reliability of the magnetic levitation fan frequency conversion drive system under transient conditions. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the magnetic levitation fan frequency conversion drive device and harmonic suppression method of the present invention;

[0061] Figure 2 This is a schematic diagram of the data flow in this invention;

[0062] Figure 3 This is a schematic flowchart of the method for obtaining PWM signals according to the present invention;

[0063] Figure 4 This is a schematic diagram of the magnetic levitation fan frequency conversion drive device of the present invention. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] Example 1:

[0066] Please see Figure 1 and Figure 2 As shown, this embodiment provides a harmonic suppression method for a magnetic levitation fan frequency converter drive device, including:

[0067] The system collects stator three-phase current, stator terminal voltage, and rotor mechanical speed to monitor the motor status and determine whether it has entered a transient operation process. When a transient operation process is entered, the phase compensation mechanism is activated; otherwise, the motor status is monitored. The magnetic levitation fan is a complete device that includes a magnetic levitation motor, a magnetic levitation bearing system, a fan impeller, and a frequency converter. The motor is the magnetic levitation motor in the magnetic levitation fan.

[0068] Methods for determining whether a transient process has been entered include:

[0069] The electric angular velocity of the motor is calculated based on the rotor's mechanical speed; for example, the electric angular velocity of the motor. ,in, The rotor's mechanical speed; This refers to the number of pole pairs of the motor; or based on the motor's electrical frequency. Calculate the electric angular velocity of the motor, such as the electric angular velocity of the motor. ;

[0070] The Clarke transform converts three-phase current into two-phase quiescent current; for example... ,in, , and It is a three-phase current; and In two stationary coordinate systems respectively Channel current components and Channel current components;

[0071] Based on the Park transform, two-phase stationary currents are converted into two-phase rotating currents, yielding the d-axis and q-axis currents; for example... ,in, For the electric angle of the motor; This refers to the direct-axis current, i.e., the d-axis current. This is the quadrature-axis current, i.e., the q-axis current;

[0072] The motor output electromagnetic torque is calculated based on the d-axis current, q-axis current, number of motor pole pairs, and permanent magnet flux linkage; for example, the motor output electromagnetic torque... ,in, This represents the number of pole pairs of the motor. For permanent magnet flux linkage; It is the d-axis inductance; It is the q-axis inductance;

[0073] The rate of change of torque is obtained by statistically analyzing the output electromagnetic torque of the motor; for example... ,in, Sampling time; for The motor outputs electromagnetic torque at all times; for The motor outputs electromagnetic torque at all times; The sampling period;

[0074] The grid voltage drop is calculated based on the stator terminal voltage and the rated line voltage. When the torque change rate is greater than the first torque change rate threshold, or the grid voltage drop is greater than the drop threshold, it is determined that the transient operation process has been entered, and the phase compensation mechanism is activated. Otherwise, it is determined that the transient operation process has not been entered, and the steady-state compensation parameters are used to perform phase compensation calculation.

[0075] Methods for calculating phase compensation using steady-state compensation parameters include:

[0076] Collect key steady-state operating parameters of the motor through sensors or controllers, including rotor mechanical speed and load rate;

[0077] From the pre-constructed control loop phase lag diagram, the corresponding steady-state phase lag is matched according to the current key steady-state operating parameters. This lag is the average value obtained through previous static operating condition simulations. For example, under fixed speed and fixed load, harmonics are injected to simulate the operating conditions to eliminate random errors under steady state, thus obtaining the basic parameters that can be directly used as steady-state compensation.

[0078] The steady-state phase lag value obtained from the query is used as the total steady-state phase compensation value. Since the phase response characteristics of the motor control system are stable and there are no drastic fluctuations under steady state, the total steady-state phase compensation value is equal to the steady-state phase lag value obtained from the query, and there is no need to add the phase lag prediction value.

[0079] The calculated steady-state total phase compensation is substituted into the phase calculation of the anti-phase harmonic voltage: after calculating the original voltage phase based on the nth harmonic current and harmonic impedance, the steady-state total phase compensation is superimposed to obtain the compensated target voltage phase. Subsequently, the anti-phase harmonic voltage can be synthesized based on this corrected phase, and then a PWM signal is generated by SVPWM and injected into the frequency converter to achieve harmonic cancellation under steady state.

[0080] The above steps can capture transient scenarios such as load changes and grid voltage drops in real time. By activating the phase compensation mechanism in a timely manner, the phase of the anti-phase harmonic injection is adjusted, avoiding the timing mismatch problem of anti-phase harmonic injection caused by drastic changes in the phase response characteristics of the control system during transient processes in existing technologies. This achieves accurate cancellation of harmonics under transient conditions and reduces the instantaneous impact of electromagnetic torque.

[0081] The three-phase current of the magnetic levitation motor is collected and coordinate transformed to obtain the d-axis and q-axis currents. Harmonics in the d-axis and q-axis currents are modeled to obtain harmonic components. These harmonic components are extracted to obtain the input vector and network weight vector. The weights in the weight vector are updated using the normalized least mean square algorithm to obtain the updated weight vector. The nth phase is then calculated based on the updated weight vector. Subharmonic current;

[0082] Methods for obtaining input vectors and network weight vectors include:

[0083] The harmonics in the d-axis and q-axis currents are modeled as a unified harmonic magnetomotive force model; for example... ,in, for The harmonic current component along the d-axis at time 1; For the first q-axis harmonic current components at the sampling time; The imaginary unit; For harmonic order; This is an integer used to define the range of harmonic orders of the motor's characteristic harmonics; For the first Subharmonic current vector The amplitude of the harmonic current can be directly calculated from the weight vector in subsequent steps, such as... , As the initial phase, it can be directly calculated from the weight vector in subsequent steps, such as... , It is a mathematical constant; For Complex exponent of rotation; The electric angular velocity of the motor;

[0084] The harmonic magnetomotive force model is expanded using Euler's formula; such as ;

[0085] Obtain simplified d-axis harmonic current components and q-axis harmonic current components. ,in, For the first The projection of the second harmonic current component onto the cosine basis; For the first The projection of the subharmonic current component onto the sinusoidal base;

[0086] Extract the sine and cosine terms of each harmonic in the simplified d-axis and q-axis harmonic current components to form the input vector; extract the projections of each harmonic current component onto the cosine basis and onto the sine basis to form the network weight vector.

[0087] Methods for obtaining updated weight vectors include:

[0088] Based on the d-axis current reference value or the q-axis current reference value, and the first... The actual value of the d-axis current or the actual value of the q-axis current at the sampling time is used to calculate the first... Error at sampling time; such as the first Error at sampling time ,in, For the first Reference value of d-axis current or q-axis current at the sampling time; For the first The actual value of the d-axis current or the actual value of the q-axis current at the sampling time;

[0089] Combined with the Error at sampling time and the first The input vector at each sampling time is used to update the weights in the weight vector based on the normalized least mean square algorithm to obtain the updated weight vector; as shown in the example. Weight vector at sampling time ,in, For the first The weight vector at each sampling time; The learning rate; The input vector; For norm, , It is the transpose of the vector; To avoid tiny positive numbers with a denominator of 0.

[0090] The above steps can accurately and dynamically identify the harmonic components in the d-axis and q-axis currents during transient processes such as load changes and grid voltage drops. The adaptively updated weight vector ensures the real-time accuracy of the harmonic parameters, providing a precise target basis for subsequent anti-phase harmonic injection. This avoids harmonic identification deviations caused by drastic changes in the phase response characteristics of the control system under transient conditions, ensures accurate cancellation of anti-phase harmonics and actual interference harmonics, and reduces the instantaneous impact of electromagnetic torque.

[0091] Construct a phase lag diagram of the control loop; monitor and determine the system status in real time, obtain the phase compensation amount based on the phase lag diagram of the control loop, and obtain the compensation phase;

[0092] Methods for constructing the phase lag spectrum of the control loop include:

[0093] The phase lag under static and dynamic operating conditions was simulated and analyzed respectively.

[0094] The operating data and corresponding phase lag values ​​are stored in tabular form to obtain the phase lag spectrum of the control loop.

[0095] Methods for simulating and analyzing phase lag under static operating conditions include:

[0096] Step 1: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage and maintain the rated voltage change rate. Below the rate of change threshold;

[0097] Step 2: The controller sends a voltage command to the d-axis of the inverter, superimposed with the first... The harmonic voltage is obtained by generating a harmonic voltage command; the harmonic voltage command is continuously output for a duration of not less than L harmonic cycles.

[0098] Step 3: Simultaneously acquire the d-axis harmonic current and the harmonic voltage command output by the controller, and perform FFT analysis to extract the d-axis harmonic voltage. The phase of the subharmonic is calculated to obtain the static phase lag; the measurement is repeated K times, and the average value of the K static phase lags is taken as the corresponding phase lag amount;

[0099] Step 4, Keep If the load rate is 0, the load rate is switched sequentially from the target load value according to the first load gradient, and the motor speed is switched sequentially from the target speed according to the first speed gradient. At each load rate and at each speed, a preset sequence of harmonic signals is injected sequentially. Steps 2-3 are repeated to obtain all static operating condition data and the corresponding phase lag.

[0100] Methods for simulating and analyzing phase lag under dynamic operating conditions include:

[0101] Step A: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage, and measure the rate of change of the output rated voltage. Once the current falls below the rate of change threshold, record the current at this point as the fundamental current.

[0102] Step B: Send a voltage drop command to the programmable AC power supply to control the output of the programmable AC power supply to drop from the rated voltage to the target voltage within a preset time period; at the same time, the controller injects a harmonic voltage command of preset duration into the d-axis; wherein, the preset duration covers the voltage drop transient and the initial recovery period;

[0103] Step C: Acquire fundamental voltage, harmonic voltage commands, and voltage sag waveform data; extract transient data within the second preset time period after the voltage sag occurs, divide the transient data into preset time windows, and calculate the voltage sag waveform within each time window. Phase difference of subharmonics; take the maximum value of phase difference within each time window as the corresponding transient phase lag;

[0104] Step D: Keep the load torque and speed constant, and switch the voltage drop amplitude from the rated voltage according to the voltage drop load gradient; under each voltage drop amplitude, inject the preset sequence of harmonic signals in sequence, and repeat steps BC.

[0105] Step E: Switch the load rate sequentially from the target load value according to the second load gradient, and then switch the motor speed sequentially from the target speed according to the second speed gradient. Repeat steps A and D at each load rate and at each speed to obtain all dynamic operating condition data and the corresponding phase lag.

[0106] The above steps simulate static and dynamic operating conditions respectively. The system measures and stores the phase lag of the control loop under each condition to form a control loop phase lag spectrum. In actual operation, the corresponding phase lag can be quickly obtained by querying the spectrum based on the real-time operating conditions of transient processes such as load changes and grid voltage drops. This allows for precise adjustment of the injection phase of the anti-phase harmonics, avoiding mismatch in the timing of anti-phase harmonic injection caused by drastic changes in the phase response characteristics of the control system under transient conditions. This achieves precise harmonic cancellation and effectively reduces the instantaneous impact of electromagnetic torque.

[0107] Methods for obtaining the compensated phase include:

[0108] Collect the current speed and load torque, and obtain the corresponding current phase lag from the control loop phase lag diagram.

[0109] The above steps collect the current speed and load torque of the motor, and accurately query the current phase lag amount under the corresponding operating condition from the pre-constructed control loop phase lag spectrum to achieve accurate harmonic cancellation, thereby reducing the instantaneous impact of electromagnetic torque.

[0110] According to the The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics.

[0111] Reference Figure 3 Methods for obtaining PWM signals include:

[0112] The first was obtained from the fundamental frequency electric angular velocity. The electric angular velocity of the second harmonic is based on the first harmonic. The electric angular velocity of the second harmonic was calculated to obtain the... Second harmonic impedance; such as the first Subharmonic electric angular velocity , No. Subharmonic impedance ,in, The fundamental electrical angular velocity; For resistance; It is an inductor;

[0113] According to the The original voltage amplitude is obtained by calculating the second harmonic impedance and harmonic current amplitude; based on the first harmonic impedance and harmonic current amplitude... The phase angle of the harmonic impedance is obtained by calculating the phase angle of the harmonic impedance. The initial phase of the subharmonic is calculated to obtain the original voltage phase; such as the original voltage amplitude. Original voltage phase , For the first The initial phase of the subharmonic; For the first The phase angle of the subharmonic impedance; where... For the first Subharmonic impedance magnitude ;

[0114] The compensated voltage phase is calculated based on the total phase compensation and the original voltage phase; for example, the compensated voltage phase. ,in, This represents the total phase compensation amount;

[0115] The original anti-phase voltage vector is obtained by calculating the original voltage amplitude and the compensated voltage phase; for example, the original anti-phase voltage vector... ;

[0116] The original inverting voltage vector is decomposed into dq-axis components to obtain the inverting harmonic voltage components. These inverting harmonic voltage components are then superimposed with the fundamental dq-axis voltage command to obtain the total voltage command. (Example: Inverting harmonic voltage components...) Total voltage command ,in, The d-axis inverse harmonic voltage component; This represents the q-axis inverted harmonic voltage component. The voltage component along the d-axis; This refers to the q-axis voltage component. This represents the total voltage component along the d-axis. This represents the total voltage component along the q-axis.

[0117] Convert the total voltage command to a voltage command in a two-phase stationary coordinate system; for example... ,in, In a two-phase stationary coordinate system Channel voltage command; In a two-phase stationary coordinate system Channel voltage command; For the electric angle of the motor;

[0118] The voltage command in the two-phase stationary coordinate system is normalized to the DC bus voltage to obtain the normalized voltage vector.

[0119] Will The plane is divided into 6 sectors. The sector where the normalized voltage vector is located is determined based on the sign and magnitude of the voltage command in the two-phase stationary coordinate system.

[0120] Methods for determining the sector containing the normalized voltage vector include:

[0121] Auxiliary variables are obtained by calculating the normalized voltage vector;

[0122] Define a sign function and calculate the M value using auxiliary variables; where the M value is an intermediate discriminant variable used to determine the sector where the voltage space vector is located.

[0123] Based on the preset correspondence between M value and sector number, the sector corresponding to the normalized voltage vector is obtained.

[0124] Calculate the duration of action of the two adjacent effective vectors and the duration of action of the zero vector in the sector containing the normalized voltage vector;

[0125] Based on the effective vector and zero vector corresponding to the sector where the normalized voltage vector is located, the time is allocated according to the principle of symmetrical modulation; such as the basic switching timing. The second switching moment The third switching moment The fourth crucial moment ,in, The SVPWM modulation period; The duration of the first adjacent effective voltage vector in the sector containing the normalized voltage vector; The duration of the second adjacent effective voltage vector in the sector containing the normalized voltage vector; Three-phase PWM comparison value: Phase A: High-level time Duty cycle Phase B: High-level time Duty cycle C phase: High level time Duty cycle ;

[0126] The three-phase duty cycle is used as the input to the controller's PWM module to obtain the PWM signal for controlling the IGBTs. If the three-phase IGBT inverter bridge topology is a standard two-level structure, the switching state is defined as 1 when conducting and 0 when turning off. The upper bridge arm Q1 corresponds to phase A, Q3 corresponds to phase B, and Q5 corresponds to phase C; the lower bridge arm Q2 corresponds to phase A, Q4 corresponds to phase B, and Q6 corresponds to phase C. Among them, Q1 and Q2 conduct complementaryly, Q3 and Q4 conduct complementaryly, and Q5 and Q6 conduct complementaryly. The dead time is forcibly inserted by a hardware timer.

[0127] The three-phase duty cycle is converted into A, B, and C three-phase comparison values, and the timer period register of the controller's PWM module is set to... The dead-time register is set to the dead time, the comparison register is loaded with the comparison values ​​of phases A, B, and C, and 6 PWM signals are output. When the timer count is not greater than the comparison value, the upper bridge arm is turned on and the lower bridge arm is turned off; otherwise, the upper bridge arm is turned off and the lower bridge arm is turned on. This can be achieved by configuring the PWM polarity register.

[0128] The above steps deeply integrate the total phase compensation amount to adapt to transient phase response changes into the calculation of anti-phase harmonic voltage. Combined with the precise sector determination, precise vector action time allocation, and precise dead zone control at the hardware level in the space vector pulse width modulation method, it ensures that the anti-phase harmonic can be injected at the timing and amplitude that perfectly matches the actual transient harmonic phase. This effectively solves the problem of timing mismatch of anti-phase harmonic injection caused by drastic changes in phase response characteristics under transient conditions such as load change and grid voltage drop, and achieves precise harmonic cancellation, thereby significantly reducing the instantaneous impact of electromagnetic torque.

[0129] Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions.

[0130] The methods for determining safety logic based on the motor's output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions, include:

[0131] After injecting harmonics, the real-time output electromagnetic torque and real-time torque change rate of the motor are analyzed and obtained.

[0132] If the real-time torque change rate exceeds the second torque change rate threshold and the duration exceeds the time threshold, it is determined to be a suppression failure. The weight vector update is immediately stopped, the harmonic voltage command amplitude is exponentially decayed to 0, and control is switched to a pure fundamental PI controller. Simultaneously, a torque impact alarm signal is output, and the fault status is recorded. ,in, The decay period can be adjusted according to the actual situation; This is the attenuated harmonic voltage command amplitude; The harmonic voltage command amplitude before attenuation;

[0133] If the suppression is successful, the real-time output electromagnetic torque and real-time torque change rate of the motor will be continuously monitored.

[0134] The above steps involve real-time detection of the motor output electromagnetic torque and real-time torque change rate after injecting anti-phase harmonics. The failure criterion is that the real-time torque change rate is greater than the second torque change rate threshold and the duration exceeds the time threshold. Once a failure is determined, the weight vector update is immediately stopped, the harmonic voltage command amplitude is decayed to zero exponentially, and pure fundamental PI control is switched. At the same time, an alarm signal is output to record the fault status. If the suppression is successful, torque-related parameters are continuously monitored. This approach can accurately capture the mismatch problem caused by the injection of anti-phase harmonics due to drastic changes in phase response characteristics under transient conditions. Through rapid and smooth failure handling actions, it avoids further aggravation of torque impact caused by mismatch. At the same time, continuous monitoring ensures the torque stability of the system when the suppression is successful, providing a safety redundancy for transient harmonic suppression. This effectively makes up for the shortcomings of existing technologies that lack post-failure protection mechanisms under transient conditions and are prone to aggravated torque impact due to mismatch.

[0135] Example 2:

[0136] Please see Figure 4 As shown, this embodiment provides a magnetic levitation fan frequency converter drive device, including:

[0137] Transient detection module: Collects stator three-phase current, stator terminal voltage and rotor mechanical speed, monitors motor status, determines whether it has entered a transient operation process, and activates the phase compensation mechanism when it enters a transient operation process; otherwise, it continues to monitor the motor status.

[0138] The data acquisition and analysis module acquires the three-phase current of the magnetic levitation motor and performs coordinate transformation to obtain the d-axis and q-axis currents. It models the harmonics in the d-axis and q-axis currents, obtains the harmonic components, extracts the harmonic components to obtain the input vector and network weight vector, and updates the weights in the weight vector based on the normalized least mean square algorithm using the input vector to obtain the updated weight vector. The module then calculates the first... Subharmonic current;

[0139] Phase compensation module: Constructs a phase lag diagram of the control loop; monitors and judges the system status in real time, obtains the phase compensation amount based on the phase lag diagram of the control loop, and obtains the compensated phase;

[0140] Signal synthesis module: based on the first The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics.

[0141] Monitoring and protection module: Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and trigger corresponding protection actions.

[0142] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0143] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A harmonic suppression method for a magnetic levitation fan variable frequency drive device, characterized in that, include: The system collects stator three-phase current, stator terminal voltage, and rotor mechanical speed to monitor the motor status and determine whether it has entered a transient operation process. If it has entered a transient operation process, the phase compensation mechanism is activated; otherwise, the system continues to monitor the motor status. The three-phase current of the magnetic levitation motor is collected and the coordinates are transformed to obtain the direct-axis current and quadrature-axis current; Harmonics in direct-axis and quadrature-axis currents are modeled to obtain harmonic components. These components are then extracted to obtain input vectors and network weight vectors. Combining the input vectors, the weights in the weight vectors are updated using the normalized least mean square algorithm to obtain updated weight vectors. The nth harmonic is then calculated based on these updated weight vectors. Subharmonic current; Construct the phase lag diagram of the control loop; The system status is monitored and judged in real time, and the phase compensation amount is obtained based on the phase lag diagram of the control loop to obtain the compensated phase. The method for constructing the phase lag diagram of the control loop includes: simulating and analyzing the phase lag amount under dynamic operating conditions. Step A: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage, and measure the rate of change of the output rated voltage. Once the current falls below the rate of change threshold, it is recorded as the fundamental current. Step B: Send a voltage drop command to the programmable AC power supply to control the output of the programmable AC power supply to drop from the rated voltage to the target voltage within a preset time period; at the same time, the controller injects a harmonic voltage command of preset duration into the direct axis. Step C: Acquire fundamental voltage, harmonic voltage commands, and voltage sag waveform data; extract transient data within the second preset time period after the voltage sag occurs, divide the transient data into preset time windows, and calculate the voltage sag waveform within each time window. Phase difference of subharmonics; take the maximum value of phase difference within each time window as the corresponding transient phase lag; Step D: Keep the load torque and speed constant, and switch the voltage drop amplitude from the rated voltage according to the voltage drop load gradient; under each voltage drop amplitude, inject the preset sequence of harmonic signals in sequence, and repeat steps BC. Step E: Switch the load rate sequentially from the target load value according to the second load gradient, and then switch the motor speed sequentially from the target speed according to the second speed gradient. Repeat steps A and D at each load rate and at each speed to obtain all dynamic operating condition data and the corresponding phase lag. According to the The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics. Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions.

2. The harmonic suppression method for the frequency conversion drive equipment of the magnetic levitation fan according to claim 1, characterized in that, Methods for constructing the phase lag spectrum of the control loop include: The phase lag under static and dynamic operating conditions was simulated and analyzed respectively. The operating data and corresponding phase lag values ​​are stored in tabular form to obtain the phase lag spectrum of the control loop.

3. The harmonic suppression method for the frequency conversion drive equipment of a magnetic levitation fan according to claim 2, characterized in that, Methods for simulating and analyzing phase lag under static operating conditions include: Step 1: Set the fan load to the target load value and the speed to the target speed; control the programmable AC power supply to output the rated voltage and maintain the rated voltage change rate. Below the rate of change threshold; Step 2: The controller sends a direct-axis voltage command to the inverter, which is then superimposed with the first... The harmonic voltage is obtained by generating a harmonic voltage command; the harmonic voltage command is continuously output for a duration of not less than L harmonic cycles. Step 3: Simultaneously acquire the direct-axis harmonic current and the harmonic voltage command output by the controller, and perform FFT analysis to extract the first harmonic current. The phase of the subharmonic is calculated to obtain the static phase lag; the measurement is repeated K times, and the average value of the K static phase lags is taken as the corresponding phase lag amount; Step 4, Keep If the load rate is 0, the load rate is switched sequentially from the target load value according to the first load gradient, and the motor speed is switched sequentially from the target speed according to the first speed gradient. At each load rate and at each speed, a preset sequence of harmonic signals is injected sequentially. Steps 2-3 are repeated to obtain all static operating condition data and the corresponding phase lag.

4. The harmonic suppression method for the frequency conversion drive equipment of the magnetic levitation fan according to claim 1, characterized in that, Methods for obtaining the compensated phase include: Collect the current speed and load torque, and obtain the corresponding current phase lag from the control loop phase lag diagram.

5. The harmonic suppression method for the frequency conversion drive equipment of a magnetic levitation fan according to claim 1, characterized in that, Methods for obtaining PWM signals include: The first was obtained from the fundamental frequency electric angular velocity. The electric angular velocity of the second harmonic is based on the first harmonic. The electric angular velocity of the second harmonic was calculated to obtain the... Subharmonic impedance; According to the The original voltage amplitude is obtained by calculating the second harmonic impedance and harmonic current amplitude; based on the first harmonic impedance and harmonic current amplitude... The phase angle of the harmonic impedance is obtained by calculating the phase angle of the harmonic impedance. The initial phase of the subharmonic is calculated to obtain the original voltage phase; The compensated voltage phase is calculated based on the total phase compensation and the original voltage phase; the original anti-phase voltage vector is calculated based on the original voltage amplitude and the compensated voltage phase; the original anti-phase voltage vector is decomposed into dq-axis components to obtain anti-phase harmonic voltage components; the anti-phase harmonic voltage components are superimposed with the fundamental dq-axis voltage command to obtain the total voltage command; the total voltage command is converted into a voltage command in a two-phase stationary coordinate system; the voltage command in the two-phase stationary coordinate system is normalized to the DC bus voltage to obtain the normalized voltage vector; The plane is divided into 6 sectors. Based on the sign and amplitude of the voltage command in the two-phase stationary coordinate system, the sector where the normalized voltage vector is located is determined. The action time of the two adjacent effective vectors and the action time of the zero vector in the sector where the normalized voltage vector is located are calculated. Based on the effective vector and zero vector corresponding to the sector where the normalized voltage vector is located, the time is allocated according to the principle of symmetrical modulation. The three-phase duty cycle is used as the input of the controller PWM module to obtain the PWM signal for controlling the IGBT.

6. The harmonic suppression method for the frequency conversion drive equipment of the magnetic levitation fan according to claim 5, characterized in that, Methods for determining the sector containing the normalized voltage vector include: Auxiliary variables are obtained by calculating the normalized voltage vector; Define a symbolic function and calculate the value of M using auxiliary variables; Based on the preset correspondence between M value and sector number, the sector corresponding to the normalized voltage vector is obtained.

7. The harmonic suppression method for the frequency conversion drive equipment of a magnetic levitation fan according to claim 1, characterized in that, Methods for obtaining input vectors and network weight vectors include: The harmonics in the direct-axis and quadrature-axis currents are uniformly modeled as a harmonic magnetomotive force model; the harmonic magnetomotive force model is expanded using Euler's formula; simplified direct-axis and quadrature-axis harmonic current components are obtained; the sine and cosine terms of each harmonic in the simplified direct-axis and quadrature-axis harmonic current components are extracted to form the input vector; the projections of each harmonic current component on the cosine basis and the projections on the sine basis are extracted to form the network weight vector.

8. The harmonic suppression method for the frequency conversion drive equipment of the magnetic levitation fan according to claim 1, characterized in that, Methods for obtaining updated weight vectors include: Based on the direct-axis current reference value or the quadrature-axis current reference value, and the first The actual value of the direct-axis current or the actual value of the quadrature-axis current at the sampling time is used to calculate the first... Error at sampling time; combined with the first Error at sampling time and the first The input vector at the sampling time is used to update the weights in the weight vector based on the normalized least mean square algorithm to obtain the updated weight vector.

9. The harmonic suppression method for the frequency conversion drive equipment of a magnetic levitation fan according to claim 1, characterized in that, Methods for determining whether a transient process has been entered include: The electric angular velocity of the motor is calculated based on the rotor's mechanical speed. The Clarke transform is used to convert three-phase current into two-phase quiescent current. Based on the Park transformation, two-phase stationary currents are converted into two-phase rotating currents to obtain direct-axis currents and quadrature-axis currents. The output electromagnetic torque of the motor is calculated based on the direct-axis current, quadrature-axis current, number of motor pole pairs, and permanent magnet flux linkage. The rate of change of torque is obtained by statistically analyzing the electromagnetic torque output of the motor. The grid voltage drop is calculated based on the stator terminal voltage and the rated line voltage. When the torque change rate is greater than the first torque change rate threshold, or the grid voltage drop is greater than the drop threshold, it is determined that the transient operation process has been entered and the phase compensation mechanism is activated. Otherwise, it is determined that the transient operation process has not been entered.

10. The harmonic suppression method for the frequency conversion drive equipment of a magnetic levitation fan according to claim 1, characterized in that, The methods for determining safety logic based on the motor's output electromagnetic torque and real-time torque change rate, and triggering corresponding protection actions, include: After injecting harmonics, the real-time output electromagnetic torque and real-time torque change rate of the motor are analyzed and obtained. If the real-time torque change rate is greater than the second torque change rate threshold and the duration exceeds the time threshold, it is determined to be a suppression failure. The weight vector update is immediately stopped, the harmonic voltage command amplitude is exponentially decayed to 0, and the control is switched to pure fundamental PI controller. At the same time, a torque impact alarm signal is output and the fault status is recorded. If the suppression is successful, the real-time output electromagnetic torque and real-time torque change rate of the motor will be continuously monitored.

11. A magnetic levitation fan frequency converter drive device, comprising the harmonic suppression method of the magnetic levitation fan frequency converter drive device according to any one of claims 1-10, characterized in that, include: Transient detection module: Collects stator three-phase current, stator terminal voltage and rotor mechanical speed, monitors motor status, determines whether it has entered a transient operation process, and activates the phase compensation mechanism when it enters a transient operation process; otherwise, it continues to monitor the motor status. The data acquisition and analysis module acquires the three-phase current of the magnetic levitation motor and performs coordinate transformation to obtain the direct-axis current and quadrature-axis current. It models the harmonics in the direct-axis and quadrature-axis currents to obtain harmonic components, extracts these components to obtain the input vector and network weight vector, and updates the weights in the weight vector based on the normalized least mean square algorithm using the input vector to obtain the updated weight vector. Finally, it calculates the first... Subharmonic current; Phase compensation module: Constructs a phase lag diagram of the control loop; monitors and judges the system status in real time, obtains the phase compensation amount based on the phase lag diagram of the control loop, and obtains the compensated phase; Signal synthesis module: based on the first The reverse harmonic voltage is obtained by calculating the sub-harmonic current, the original voltage phase, and the compensation phase. The PWM signal is then obtained by combining the space vector pulse width modulation method and injecting the PWM signal into the frequency converter to cancel harmonics. Monitoring and protection module: Real-time detection of motor output electromagnetic torque and real-time torque change rate; safety logic judgment based on motor output electromagnetic torque and real-time torque change rate, and trigger corresponding protection actions.

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