Active elimination method and device for abnormal noise in all speed ranges of BLDC motor

Abstract

The present invention relates to the technical field of noise reduction of BLDC motors, and specifically relates to a method and device for actively eliminating abnormal sounds in the full speed range of a BLDC motor. The method includes the following steps: S1: Obtain the three-phase current, electrical angle θ, and angular velocity ω of the motor, and combine the noise and spectrum data to calculate the multiple N of the noise frequency required for current harmonic compensation to the fundamental frequency, the reference coefficient X, and the compensated electrical angle N θ , and the dq-axis currents N required for noise compensation by transforming the reference coefficient X θId and N θIq ; S2: Obtain the i dref and i qref of the motor vector control system, and calculate N θ according to N θValpha and N θVbeta , and calculate the voltage compensation values N θidref and N θiqref ; S3: Calculate the compensated reference voltage vectors V θiqref alpha and V beta according to the N θ 、N θId 、N θIq 、N θidref and Ncalculated in step S1 and step S2; S4: Generate PWM signals according to the V alpha beta and Vcalculated in step S3 to control the three-phase inverter to drive the motor; it has low cost and can eliminate abnormal sounds in the full speed range and full frequency band.

Description

Technical Field

[0001] The present invention relates to the technical field of abnormal sound elimination of a permanent magnet synchronous BLDC motor system, and in particular to a method and a device for actively eliminating abnormal sound of a BLDC motor in all speed ranges. Background Art

[0002] As living standards improve, people have more and more demands for quiet air conditioners. At present, the noise reduction treatment of air conditioner fan motors is mainly achieved by modifying the material of plastic spring pads to change the hardness of the spring pads or changing the body structure, or by changing the angle of control to eliminate and suppress noise.

[0003] During the operation of the permanent magnet synchronous motor, the characteristics of the PWM switch dead time, tube voltage drop and the air gap magnetic field distortion of the motor itself will cause the motor stator phase current to be distorted, so that the stator phase current contains not only fundamental components, but also 5th, 7th, 11th, 13th and other high-order harmonic components, which can easily cause the motor torque pulsation to increase, the speed to jitter and become unstable, and may cause the motor and fan system to resonate and produce abnormal sounds. The above methods each have certain defects and can only suppress and reduce noise within a certain range. Changing the hardness of the spring pad by modifying the material of the plastic spring pad not only requires proofing spring pads with various material ratios, but also requires a large number of experiments, which not only has a long cycle, but also consumes a lot of manpower and testing. The final result can only solve the noise in certain speed and frequency bands, but can do nothing about the abnormal sound mentioned above; as for changing the main body structure, it is necessary to re-open the mold, which has a long mold opening cycle and is expensive; if the control is changed to reduce noise by changing the angle, it will directly affect the motor efficiency, and even if it can suppress certain frequency and speed noises, abnormal sounds will still appear in other speed and frequency bands.

[0004] Therefore, it is urgent to develop a method and device with low cost and capable of actively eliminating abnormal noise in the full speed range of the BLDC motor. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned existing BLDC motor noise reduction being high in cost and only being able to work in a partial speed range, and to provide a low-cost method and device for actively eliminating abnormal noise in the full speed range of the BLDC motor.

[0006] To achieve the above-mentioned purpose, the present invention is implemented in the first aspect through the following technical solutions: A method for actively eliminating abnormal noise in the full speed range of a BLDC motor, which reduces the noise of the motor based on current harmonic compensation, comprises the following steps: S1: obtaining the three-phase current, electrical angle θ, and angular velocity ω of the motor, and combining the noise and spectrum data of the motor system obtained in advance, analyzing and calculating the noise frequency and the multiple N of the fundamental frequency required for current harmonic compensation, the reference coefficient X, and the compensation electrical angle N θ , and the dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq ; S2: Get the i of the motor vector control system dref and i qref And according to the compensation electrical angle N θ , calculate the target voltage compensation value N required for active noise compensation θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref ; S3: According to N calculated in step S1 and step S2 θ 、N θId 、N θIq 、N θidref and N θiqref , calculate the compensated reference voltage vector V alpha and V beta ; S4: According to the V calculated in step S3 alpha and V beta Generate PWM signals to control the three-phase inverter to drive the motor.

[0007] A further preferred scheme of the present invention is: in the step S1, the noise and spectrum data of the motor are noise spectrum analysis information collected during the speed regulation process when the motor is not compensated; the current speed is calculated by the angular velocity ω, and the noise frequency corresponding to the speed and the multiple N of the fundamental frequency and the coefficient X are found in the noise and spectrum data according to the current speed.

[0008] A further preferred solution of the present invention is: the compensation electrical angle N θ It is the value obtained by multiplying the angular velocity ω by the multiple N and performing an integration operation.

[0009] A further preferred solution of the present invention is: the dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq The calculation formula is as follows:

[0010] N θIq =I beta *cos(N θ )*XIalpha *sin(N θ )*X (1);

[0011] N θId =I beta *sin(N θ )*X+I alpha *cos(N θ )*X (2);

[0012] Where I alpha and I beta The value is obtained by converting Ia and Ib from the rotating coordinate system to the stationary coordinate system; Ia is the a-phase current of the motor, and Ib is the b-phase current of the motor; the formula for converting the rotating coordinate system to the stationary coordinate system is:

[0013] I alpha =Ia (3);

[0014]

[0015] A further preferred solution of the present invention is: the compensated reference voltage vector V alpha and V beta The calculation process is as follows:

[0016] Calculate N θidref With N θId The deviation value is low-pass filtered to obtain N θVd ; Calculate N θiqref With N θIq The deviation value is also low-pass filtered to obtain N θVq .

[0017] N θVd and N θVq Substitute the following formula

[0018] N θValpha =-(N θVd *cos(N θ )-N θVq *sin(N θ )) (5)

[0019] N θVbeta =-(N θVq *cos(N θ )+N θVd *sin(N θ )) (6)

[0020] Calculate the voltage compensation value N θValpha and N θVbeta .

[0021] Finally, the Valpha and Vbeta values ​​obtained in advance from the motor vector control system are subtracted from the calculated voltage compensation value N θValpha and N θVbeta , and obtain the compensated reference voltage vector V alpha and V beta .

[0022] In a second aspect, the present invention provides a device for actively eliminating abnormal sounds in a BLDC motor at all speeds, which is arranged on a control circuit of the BLDC motor, wherein the control circuit of the BLDC motor includes a vector controller, a space vector pulse width modulation circuit, and a three-phase inverter connected to the BLDC motor; the device for actively eliminating abnormal sounds in a BLDC motor at all speeds adopts the method for actively eliminating abnormal sounds in a BLDC motor at all speeds as described in the first aspect, and the device for actively eliminating abnormal sounds in a BLDC motor at all speeds includes a reference value calculation module, a noise analysis module, and a noise processing module;

[0023] The noise analysis module has two sets of input terminals and a first calculation unit, one set of input terminals is coupled to the output terminal of the three-phase inverter to obtain the current three-phase current of the motor, and the other set of input terminals is coupled to the vector controller to obtain the current electrical angle θ and angular velocity ω; and the first calculation unit is used to calculate the multiple N of the noise frequency and the fundamental frequency required for current harmonic compensation, the reference coefficient X, and the compensation electrical angle N θ , and the dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq ;

[0024] The reference value calculation module has three input terminals and a second calculation unit; an input terminal is coupled to the vector controller to obtain the current i dref and i qref parameter, an input terminal coupled to the noise analysis module to obtain the compensation electrical angle N θ , and the other input end is coupled to the data storage to read the noise spectrum analysis information recorded in the data storage; and the target voltage compensation value N required for active noise compensation is calculated by the second calculation unit θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref ;

[0025] The noise processing module has a third calculation unit, which calculates the compensated reference voltage vector V according to the calculation results of the first calculation unit and the second calculation unit. alpha and V beta The calculation result is transmitted to the space vector pulse width modulation circuit so that the three-phase inverter drives the motor according to the generated PWM signal.

[0026] In summary, the present invention has the following beneficial effects: using active noise suppression (noise reduction) technology of current harmonic compensation, in combination with existing plastic spring pads without changing the main structure and installation method of the fan motor, effectively suppresses the noise (abnormal sound) caused by current vibration harmonics, and ensures the lowest operating noise in the full speed range of the motor system. This method compensates the output voltage based on the current information of actual sampling feedback, which can effectively suppress the noise caused by current vibration harmonics, with the purpose of eliminating the noise resonance caused by the air-conditioning fan motor and the system during operation, and can eliminate abnormal sounds in all speed ranges and all frequency bands. In addition, this method is simple to implement, with a small amount of computational data, and is convenient to implement in a low-cost manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural block diagram of the device for actively eliminating abnormal noise in all speed ranges of a BLDC motor according to the present invention.

[0028] Figure 2 It is a structural block diagram of the noise analysis module of the present invention.

[0029] Figure 3 It is a structural block diagram of the reference value calculation module of the present invention.

[0030] Figure 4 It is a structural block diagram of the noise processing module of the present invention.

[0031] Figure 5 It is a data line graph of the difference in spectrum noise (total noise value - noise peak value) measured before and after compensation using the abnormal sound active elimination method of the present invention.

[0032] Figure 6 and 7 The following are the noise spectrum analysis results before and after using the abnormal sound active elimination method of the present invention.

[0033] Figure 8 It is a structural schematic diagram of the BLDC motor described in the present invention.

[0034] in:

[0035] 100, vector controller; 200, space vector pulse width modulation circuit; 300, three-phase inverter; 400, motor; 510, noise analysis module; 520, reference value calculation module; 530, noise processing module. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0037] This embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

[0038] like Figure 1-4 , and 8, this embodiment provides a device for actively eliminating abnormal noise in the full speed section of a BLDC motor, which is arranged on the control circuit of a BLDC motor 400, and the control circuit of the BLDC motor 400 includes a vector controller 100, a space vector pulse width modulation circuit 200, and a three-phase inverter 300 connected to the BLDC motor 400. The device adopts a method for actively eliminating abnormal noise of a BLDC motor 400, and compensates the output voltage based on the current information of actual sampling feedback, which can effectively suppress the noise caused by current vibration harmonics, so as to eliminate the noise caused by the air conditioner fan motor 400 during operation and the system. The device for actively eliminating abnormal noise in the full speed section of a BLDC motor includes a reference value calculation module 520, a noise analysis module 510, and a noise processing module 530.

[0039] The noise analysis module has two sets of input terminals and a first calculation unit. One set of input terminals is coupled to the output terminal of the three-phase inverter to obtain the current three-phase current (through), and the other set of input terminals is coupled to the vector controller to obtain the current electrical angle θ and angular velocity ω; and the noise frequency and the multiple N of the fundamental frequency required for current harmonic compensation, the reference coefficient X, and the compensation electrical angle N are calculated by the first calculation unit. θ , and the dq axis current N required for noise compensation of the reference coefficient X conversion θId and N θIq .

[0040] The reference value calculation module has three input terminals and a second calculation unit; an input terminal is coupled to the vector controller to obtain the current i dref and i qref parameter, an input terminal coupled to the noise analysis module to obtain the compensation electrical angle N θ , and the other input end is coupled to the data storage to read the noise spectrum analysis information recorded in the data storage; and the target voltage compensation value N required for active noise compensation is calculated by the second calculation unit θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref .

[0041] The noise processing module has a third calculation unit, which calculates the compensated reference voltage vector V according to the calculation results of the first calculation unit and the second calculation unit. alpha and Vbeta The calculation result is transmitted to the space vector pulse width modulation circuit so that the three-phase inverter drives the motor according to the generated PWM signal.

[0042] The method for actively eliminating abnormal noise of BLDC motor used here is to reduce the noise of the motor based on current harmonic compensation, which mainly includes the following steps:

[0043] S1: Obtain the three-phase current, electrical angle θ, and angular velocity ω of the motor, and combine the noise and spectrum data of the motor obtained in advance to analyze and calculate the noise frequency and multiples of the fundamental frequency N required for current harmonic compensation, reference coefficient X, and compensation electrical angle N θ , and the dq axis current N required for noise compensation of the reference coefficient X conversion θId and N θIq .

[0044] S2: Get the i of the motor vector control system dref and i qref And according to the compensation electrical angle N θ , calculate the target voltage compensation value N required for active noise compensation θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref .

[0045] S3: Based on the N calculated in steps S1 and S2 θ 、N θId 、N θIq 、N θidref and N θiqref , calculate the compensated reference voltage vector V alpha and V beta .

[0046] S4: Based on the V calculated in step S3 alpha and V beta Generate PWM signals to control the three-phase inverter to drive the motor.

[0047] In step S1, the noise and spectrum data of the motor are the noise spectrum analysis information collected during the speed regulation process when the motor is not compensated; the current speed is calculated by the angular velocity ω, and the noise frequency corresponding to the speed and the multiple N of the fundamental frequency and the coefficient X are found in the noise and spectrum data according to the current speed. The compensation electrical angle N θ It is the value obtained by multiplying the angular velocity ω by the multiple N and then integrating it.

[0048] The dq axis current N required for noise compensation is converted to the reference coefficient X θId and N θIq The calculation formula is as follows:

[0049] N θIq =I beta *cos(N θ )*XI alpha *sin(N θ )*X (1);

[0050] N θId =I beta *sin(N θ )*X+I alpha *cos(N θ )*X (2);

[0051] Where I alpha and I beta The value of is obtained by converting Ia and Ib from the rotating coordinate system to the stationary coordinate system; Ia is the a-phase current of the motor, and Ib is the b-phase current of the motor;

[0052] The formula for transforming the rotating coordinate system to the stationary coordinate system is:

[0053] I alpha =Ia (3);

[0054]

[0055] Compensated reference voltage vector V alpha and V beta The calculation process is as follows:

[0056] Calculate N θidref With N θId The deviation value is low-pass filtered to obtain N θVd ; Calculate N θiqref With N θIq The deviation value is also low-pass filtered to obtain N θVq .

[0057] N θVd and N θVq Substitute the following formula

[0058] N θValpha =-(N θVd *cos(N θ )-N θVq *sin(N θ )) (5)

[0059] And the formula N θVbeta =-(N θVq *cos(N θ )+N θVd *sin(N θ )) (6)

[0060] Calculate the voltage compensation value N θValpha and N θVbe ta.

[0061] Subtract the calculated voltage compensation value N from the Valpha and Vbeta values ​​obtained in advance from the motor vector control system. θValpha and N θVbeta , and obtain the compensated reference voltage vector V alpha and V beta That is, calculate according to the following formula

[0062] V alpha =Valpha-N θValpha (7)

[0063] V beta =Vbeta-N θVbeta (8)

[0064] The above-mentioned BLDC motor full-speed range abnormal noise active elimination device and abnormal noise active elimination method are used to reduce the noise of the motor. The experimental results are as follows: Figure 5-7 .

[0065] Figure 5 It is a line graph of the data of the spectrum noise difference (total noise value - noise peak value) measured before and after compensation using the abnormal sound active elimination method of the present invention. Indicates the data before compensation, It represents the data after compensation. From the data, we can see that the difference of the data after compensation is significantly better than that before compensation. Generally, the human ear considers that a difference of ≥10dB(A) is noise-free.

[0066] Figure 6 This is the noise spectrum analysis result at a certain speed before the device uses this method. Figure 7 This is the noise spectrum analysis result at the same speed after the device uses this method.

[0067] according to Figure 6 and Figure 7 The spectrum analysis before and after compensation shows that the 160Hz noise peak is significantly reduced from 26.8dB(A) to 16.2dB(A), and the 440Hz and 580Hz noise peaks are also reduced synchronously by the method of the present invention. Therefore, the method can effectively suppress the noise caused by the current vibration harmonics, aiming to eliminate the noise resonance caused by the air conditioner fan motor during operation and the system, and realize the operation without abnormal sound in the full speed range of 200Rpm-950Rpm.

Claims

1. A method and device for actively eliminating abnormal noise in the full speed range of a BLDC motor, which reduces the noise of the motor based on current harmonic compensation. It is characterized in that The following steps are included: S1: Get the three-phase current, electrical angle θ, and angular velocity ω of the motor, and combine the noise and spectrum data of the motor system obtained in advance to analyze and calculate the noise frequency and multiples of the fundamental frequency N required for current harmonic compensation, reference coefficient X, and compensation electrical angle N θ , and the dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq ; S2: Get the i of the motor vector control system dref and i qref And according to the compensation electrical angle N θ , calculate the target voltage compensation value N required for active noise compensation θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref ; S3: Based on the N calculated in steps S1 and S2 θ 、N θId 、N θIq 、N θidref and N θiqref , calculate the compensated reference voltage vector V alpha and V beta ; S4: Based on the V calculated in step S3 alpha and V beta Generate PWM signals to control the three-phase inverter to drive the motor; The compensated reference voltage vector V alpha and V beta The calculation process is as follows: Calculate N θidref With N θId The deviation value is low-pass filtered to obtain N θVd ; Calculate N θiqref With N θIq The deviation value is also low-pass filtered to obtain N θVq ; N θVd and N θVq Substitute into the formula and calculate the voltage compensation value N θValpha and N θVbeta : a)N θValpha =-(N θVd cos(N θ )-N θVq sin(N θ )); b)N θVbeta =-(N θVq cos(N θ )+N θVd sin(N θ )); Subtract the calculated voltage compensation value N from the Valpha and Vbeta values ​​obtained in advance from the motor vector control system. θValpha and N θVbeta , and obtain the compensated reference voltage vector V alpha and V beta .

2. The method for actively eliminating abnormal noise in the full speed range of a BLDC motor according to claim 1, It is characterized in that In the step S1, the noise and spectrum data of the motor are noise spectrum analysis information collected during the speed regulation process when the motor is not compensated; the current speed is calculated by the angular velocity ω, and the noise frequency and multiples N of the fundamental frequency and the coefficient X corresponding to the speed are found in the noise and spectrum data according to the current speed.

3. The method for actively eliminating abnormal noise in the full speed range of a BLDC motor according to claim 2, It is characterized in that The compensation electrical angle N θ It is the value obtained by multiplying the angular velocity ω by the multiple N and performing an integration operation.

4. The method for actively eliminating abnormal noise in the full speed range of a BLDC motor according to claim 1, It is characterized in that The dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq The calculation formula is as follows: a)N θIq =I beta cos(N θ ) X-I alpha sin(N θ ) X; b)N θId =I beta sin(N θ ) X+I alpha cos(N θ ) X; Where I alpha and I beta The value of is obtained by converting Ia and Ib from the rotating coordinate system to the stationary coordinate system; Ia is the a-phase current of the motor, and Ib is the b-phase current of the motor; The formula for transforming the rotating coordinate system to the stationary coordinate system is: a)I alpha =Ia; b)I beta = (Ia+2 Ib) / 3。 5. A device for actively eliminating abnormal sound in the full speed range of a BLDC motor, which is arranged on a control circuit of the BLDC motor, wherein the control circuit of the BLDC motor includes a vector controller, a space vector pulse width modulation circuit, and a three-phase inverter connected to the BLDC motor; the device for actively eliminating abnormal sound in the full speed range of a BLDC motor adopts a method for actively eliminating abnormal sound in the full speed range of a BLDC motor as described in any one of claims 1 to 4, It is characterized in that The BLDC motor full-speed section abnormal noise active elimination device comprises a reference value calculation module, a noise analysis module, and a noise processing module; The noise analysis module has two sets of input terminals and a first calculation unit, one set of input terminals is coupled to the output terminal of the three-phase inverter to obtain the current three-phase current of the motor, and the other set of input terminals is coupled to the vector controller to obtain the current electrical angle θ and angular velocity ω; The first calculation unit calculates the multiple N of the noise frequency and the fundamental frequency required for current harmonic compensation, the reference coefficient X, and the compensation electrical angle N. θ , and the dq axis current N required for the reference coefficient X conversion noise compensation θId and N θIq ; The reference value calculation module has three input terminals and a second calculation unit; an input terminal is coupled to the vector controller to obtain the current i dref and i qref parameter, an input terminal coupled to the noise analysis module to obtain the compensation electrical angle N θ , the other input end is coupled to the data storage device to read the noise spectrum analysis information recorded in the data storage device; The target voltage compensation value N required for active noise compensation is calculated by the second calculation unit. θValpha and N θVbeta , calculate the voltage compensation value N θidref and N θiqref ; The noise processing module has a third calculation unit, which calculates the compensated reference voltage vector V according to the calculation results of the first calculation unit and the second calculation unit. alpha and V beta The calculation result is transmitted to the space vector pulse width modulation circuit so that the three-phase inverter drives the motor according to the generated PWM signal.

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