Motor current low-frequency oscillation suppression method and device, driving system without electrolytic capacitor and motor

Abstract

The invention discloses a motor current low-frequency oscillation suppression method and device, an electrolytic-capacitor-free driving system and a motor, and relates to the field of permanent magnet synchronous motor control, and the method comprises the steps: determining a low-frequency oscillation frequency component in motor current according to a motor voltage fundamental wave frequency and a bus voltage fluctuation frequency, a low-frequency oscillation frequency component in motor current is separated through a band-pass filter to obtain d-q-axis low-frequency oscillation frequency current, a current difference value is determined through the current and preset current, PI adjustment is carried out, a compensation voltage vector is determined, and the driving voltage of the motor is adjusted through the compensation voltage vector. Compared with the prior art, the method is applied to the non-electrolytic-capacitor driving system, the acquired d-q-axis low-frequency oscillation frequency current is compared with the preset current, PI adjustment is performed, the compensation voltage vector is determined, voltage deviation caused by bus voltage fluctuation in the non-electrolytic-capacitor driving system is offset, and motor current low-frequency oscillation is eliminated.

Description

Technical Field

[0001] The present application relates to the field of permanent magnet synchronous motor control, and in particular to a method and device for suppressing low-frequency oscillation of motor current, an electrolytic capacitor-free drive system, and a motor. Background Art

[0002] Traditional motor drive systems mostly use AC-DC-AC structures, mainly including uncontrolled rectifiers, PFC power factor correction parts, DC bus voltage maintenance parts and inverter parts. Bus capacitors usually choose large-capacity aluminum electrolytic capacitors to maintain the stability of the bus voltage. However, large-capacity electrolytic capacitors not only have the disadvantages of large size and weight, but also their service life is easily affected by environmental factors such as temperature, humidity, vibration and other adverse environmental factors, which can cause failures in the drive system and affect the overall performance of the system.

[0003] In order to meet the challenges in traditional motor drive systems, smaller film capacitors are used to replace the original large electrolytic capacitors, and the power factor correction (PFC) link is omitted. However, the motor drive system without electrolytic capacitors also has some shortcomings and limitations. Since the capacitance of the DC side capacitor is greatly reduced, the energy storage capacity of the capacitor is significantly reduced, so that the DC bus voltage fluctuates greatly periodically. When the motor speed is close to the DC voltage fluctuation frequency, a large number of low-frequency harmonic components will appear in the motor current, causing low-frequency oscillation of the system. Therefore, the instability of the bus voltage not only increases the difficulty of system control, but also makes the system unstable. Summary of the invention

[0004] The main purpose of the present application is to provide a method and device for suppressing low-frequency oscillation of motor current, an electrolytic capacitor-free drive system and a motor, aiming to solve the technical problem that a large number of low-frequency harmonic components will appear in the motor current in the electrolytic capacitor-free drive system, causing low-frequency oscillation of the system.

[0005] To achieve the above object, the present application provides a method for suppressing low-frequency oscillation of motor current, the method comprising:

[0006] Determine the low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency;

[0007] The low-frequency oscillation frequency component in the motor current is separated by a band-pass filter to obtain the dq-axis low-frequency oscillation frequency current;

[0008] Determining a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current;

[0009] Performing PI regulation according to the current difference and determining a compensation voltage vector;

[0010] The drive voltage of the motor is adjusted using the compensation voltage vector.

[0011] Optionally, before the step of separating the low-frequency oscillation frequency component in the motor current by a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current, the step further includes:

[0012] Determine the cutoff frequency of the bandpass filter according to the low-frequency vibration frequency component;

[0013] According to the cut-off frequency, determine the center frequency of the bandpass filter;

[0014] Create a bandpass filter based on the center frequency.

[0015] Optionally, the step of performing PI regulation according to the current difference and determining a compensation voltage vector specifically includes:

[0016] According to the current difference, PI regulation is performed and the PI regulation coefficient is determined;

[0017] The compensation voltage vector is determined according to the PI adjustment coefficient and the current difference.

[0018] Optionally, the step of performing PI regulation according to the current difference and determining the PI regulation coefficient specifically includes:

[0019] Perform PI adjustment based on current error;

[0020] By establishing a mathematical model, the PI adjustment parameters are determined.

[0021] In addition, to achieve the above purpose, the present application also proposes a device for suppressing low-frequency oscillation of motor current, the device comprising:

[0022] A determination module, used to determine the low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency;

[0023] A separation module, used for separating the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current;

[0024] A difference module, used to determine a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current;

[0025] A regulating module, used for performing PI regulation according to the current difference and determining a compensation voltage vector;

[0026] The compensation module is used to adjust the driving voltage of the motor using the compensation voltage vector.

[0027] In addition, to achieve the above-mentioned purpose, the present application also proposes an electrolytic capacitor-free driving system, and the electrolytic capacitor-free driving system includes the motor current low-frequency oscillation suppression method as described above.

[0028] In addition, to achieve the above-mentioned purpose, the present application also proposes a motor, which includes the motor current low-frequency oscillation suppression method as described above.

[0029] One or more technical solutions proposed in this application have at least the following effects:

[0030] The present application determines the low-frequency oscillation frequency component in the motor current according to the fundamental frequency of the motor voltage and the bus voltage fluctuation frequency, separates the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current, determines the current difference according to the dq-axis low-frequency oscillation frequency current and the preset dq-axis low-frequency oscillation frequency current, performs PI adjustment according to the current difference, and determines the compensation voltage vector, and uses the compensation voltage vector to adjust the drive voltage of the motor. Compared with the traditional motor drive system using large-capacity electrolytic capacitors, the present application is applied to the electrolytic capacitor-free drive system, and the PI adjustment is performed by comparing the collected dq-axis low-frequency oscillation frequency current with the preset current, and the compensation voltage vector is determined to offset the voltage deviation caused by the bus voltage fluctuation in the electrolytic capacitor-free drive system, so as to eliminate the low-frequency oscillation of the motor current and improve the robustness and dynamic performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 A schematic diagram of the flow chart of the first embodiment of the method for suppressing low-frequency oscillation of motor current proposed in the embodiment of the present application;

[0033] Figure 2 A schematic diagram of a flow chart of a second embodiment of a method for suppressing low-frequency oscillation of a motor current proposed in an embodiment of the present application;

[0034] Figure 3 A schematic flow chart of a third embodiment of a method for suppressing low-frequency oscillation of a motor current proposed in an embodiment of the present application;

[0035] Figure 4 A schematic flow chart of a fourth embodiment of a method for suppressing low-frequency oscillation of a motor current proposed in an embodiment of the present application;

[0036] Figure 5This is a schematic diagram of the module structure of the motor current low-frequency oscillation suppression device according to an embodiment of the present application;

[0037] Figure 6 This is an overall block diagram of the application of the control strategy proposed in the embodiment of the present application;

[0038] Figure 7 is the Bode plot of the bandpass filter;

[0039] Figure 8 The motor current waveform diagram is when the given motor speed is 5400r / min and the low-frequency oscillation suppression strategy of the present invention is not adopted;

[0040] Fig. 9 The motor current harmonic diagram is when the given motor speed is 5400r / min and the low-frequency oscillation suppression strategy of the present invention is not adopted;

[0041] Fig.10 The motor current waveform diagram when the motor is given a speed of 5400 r / min and the low-frequency oscillation suppression strategy of the present invention is adopted;

[0042] Fig.11 The motor current harmonic diagram is when the motor has a given speed of 5400 r / min and the low-frequency oscillation suppression strategy of the present invention is adopted;

[0043] Fig.12 The motor current waveform diagram is when the given motor speed is 5700r / min and the low-frequency oscillation suppression strategy of the present invention is not adopted;

[0044] Fig.13 The motor current harmonic diagram is when the given motor speed is 5700r / min and the low-frequency oscillation suppression strategy of the present invention is not adopted;

[0045] Fig.14 The motor current waveform diagram when the motor is given a speed of 5700r / min and the low-frequency oscillation suppression strategy of the present invention is adopted;

[0046] Fig.15 This is a diagram of motor current harmonics when the motor has a given speed of 5700 r / min and the low-frequency oscillation suppression strategy of the present invention is adopted.

[0047] Description of Figure Numbers:

[0048]

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0050] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0053] The main solution of the embodiment of the present application is: by comparing the collected dq-axis low-frequency oscillation frequency current with the preset dq-axis low-frequency oscillation frequency current and then performing PI adjustment, the compensation voltage vector is determined to offset the voltage deviation caused by the bus voltage fluctuation in the electrolytic capacitor-free drive system, so as to eliminate the low-frequency oscillation of the motor current.

[0054] In this embodiment, for the convenience of description, the following description is made by taking the microcontroller of the electrolytic capacitor-free driving system as the execution subject.

[0055] In order to meet the challenges in traditional motor drive systems, smaller film capacitors are used to replace the original large electrolytic capacitors, and the power factor correction (PFC) link is omitted. However, the motor drive system without electrolytic capacitors also has some shortcomings and limitations. Since the capacitance of the DC side capacitor is greatly reduced, the energy storage capacity of the capacitor is significantly reduced, so that the DC bus voltage fluctuates greatly periodically. When the motor speed is close to the DC voltage fluctuation frequency, a large number of low-frequency harmonic components will appear in the motor current, causing low-frequency oscillation of the system. Therefore, the instability of the bus voltage not only increases the difficulty of system control, but also makes the system unstable.

[0056] The present application provides a solution, which determines the low-frequency oscillation frequency component in the motor current according to the fundamental frequency of the motor voltage and the bus voltage fluctuation frequency, separates the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current, determines the current difference according to the dq-axis low-frequency oscillation frequency current and the preset dq-axis low-frequency oscillation frequency current, performs PI adjustment according to the current difference, and determines the compensation voltage vector, and uses the compensation voltage vector to adjust the drive voltage of the motor. Compared with the traditional motor drive system using large-capacity electrolytic capacitors, the present application is applied to the electrolytic capacitor-free drive system, and the PI adjustment is performed by comparing the collected dq-axis low-frequency oscillation frequency current with the preset current, and the compensation voltage vector is determined to offset the voltage deviation caused by the bus voltage fluctuation in the electrolytic capacitor-free drive system, so as to eliminate the low-frequency oscillation of the motor current and improve the robustness and dynamic performance of the system.

[0057] It should be noted that the main advantage of the electrolytic capacitor-free structure is that the electrolytic capacitor is completely removed and the electrolytic capacitors in the traditional motor drive solution are no longer used. The electrolytic capacitor-free design reduces the maintenance cost of the system. In addition to the increase in life and cost reduction, the electrolytic capacitor-free motor drive system also has the characteristics of high efficiency. Traditional electrolytic capacitors will produce certain energy losses during the charging and discharging process, while the electrolytic capacitor-free design reduces this part of the loss and improves the energy conversion efficiency of the system.

[0058] Based on this, an embodiment of the present application provides a method for suppressing low-frequency oscillation of motor current.

[0059] Reference Figure 1 , Figure 1 This is a flow chart of the first embodiment of the method for suppressing low-frequency oscillation of motor current proposed in the embodiment of the present application.

[0060] Considering that the capacitance of the DC side capacitor in the non-electrolytic capacitor system is greatly reduced, the energy storage capacity of the capacitor is significantly reduced, so that the DC bus voltage fluctuates greatly periodically. When the motor speed is close to the DC voltage fluctuation frequency, a large number of low-frequency harmonic components will appear in the motor current, causing low-frequency oscillation of the system, such as Figure 1 and Figure 6 As shown, the method for suppressing low-frequency oscillation of motor current in this embodiment includes steps S10 to S50:

[0061] Step S10: Determine the low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency.

[0062] It should be noted that the formula for the motor low-frequency oscillation frequency Δf is:

[0063] Δf=6f g -f b

[0064] Where Δf represents the low-frequency oscillation frequency, f g Indicates the input power frequency, f b Indicates the fundamental frequency of the motor's three-phase voltage.

[0065] Step S20: Separate the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current.

[0066] It should be noted that the bandpass filter is expressed as follows:

[0067]

[0068] Where ω0 represents the center angular frequency of the bandpass filter, Q represents the quality factor, and A(ω0) represents the center frequency gain.

[0069] Step S30: determining a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current.

[0070] It should be noted that the preset dq axis low frequency oscillation frequency current is the preset d axis current and preset q-axis current It can be set according to the actual situation, and this embodiment does not limit it. For example:

[0071] Step S40: performing PI regulation according to the current difference and determining a compensation voltage vector.

[0072] It should be noted that PI regulation is a combination of proportional control (P) and integral control (I) to achieve precise control of system output.

[0073] Step S50: using the compensation voltage vector to adjust the driving voltage of the motor.

[0074] It should be noted that the compensation voltage vector is used to adjust the driving voltage of the motor to eliminate the low-frequency oscillation of the motor current.

[0075] In this embodiment, the low-frequency oscillation frequency component in the motor current is determined according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency, and the low-frequency oscillation frequency component in the motor current is separated by a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current. The current difference is determined according to the dq-axis low-frequency oscillation frequency current and the preset dq-axis low-frequency oscillation frequency current, and PI adjustment is performed according to the current difference, and a compensation voltage vector is determined. The drive voltage of the motor is adjusted using the compensation voltage vector to offset the voltage deviation caused by the bus voltage fluctuation in the electrolytic capacitor-free drive system, so as to eliminate the low-frequency oscillation of the motor current and improve the robustness and dynamic performance of the system.

[0076] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the first embodiment can refer to the above introduction, and will not be repeated in the following. Figure 2 , Figure 2 This is a flow chart of a second embodiment of the method for suppressing low-frequency oscillation of motor current proposed in an embodiment of the present application.

[0077] Considering that the low-frequency oscillation frequency component in the motor current is separated by a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current, in order to design a bandpass filter, such as Figure 2 and Figure 7 As shown, Figure 7 To select a desired frequency for the bandpass filter, in this embodiment, before step S20, the following steps are further included:

[0078] Step S201: Determine the cutoff frequency of the bandpass filter according to the low-frequency vibration frequency component.

[0079] Step S202: Determine the center frequency of the bandpass filter according to the cutoff frequency.

[0080] It should be noted that the center frequency can be approximately calculated by the geometric mean of the lower cutoff frequency and the upper cutoff frequency, or can be set according to actual conditions. This embodiment is not limited thereto. For example, the center frequency ω0 calculation formula can be expressed as:

[0081] ω0=2π(6f g -f b )

[0082] Step S203: Establish a bandpass filter according to the center frequency.

[0083] It should be noted that, in an ideal situation, when constructing a mathematical model for mathematical reasoning, the bandpass filter can be simplified to a series connection of a high-pass filter and a low-pass filter, which can be expressed as:

[0084]

[0085] Where ω is the filter frequency and s is a constant.

[0086] Among them, the formula of the open-loop transfer function G(s) can be expressed as:

[0087]

[0088] Where, T s is the dead time, T d To calculate the delay time, L q is the q-axis inductance, K p is the proportional adjustment parameter, K i is the integral adjustment parameter.

[0089] Among them, the phase margin It refers to the difference between the phase angle and -180° when the amplitude of the system's open-loop frequency characteristic is equal to 1 (or the gain is 0dB). It is used to evaluate the system's resistance to frequency disturbances and instability. The phase margin It can be set according to the actual situation, and this embodiment does not limit it. For example: The formula can be expressed as:

[0090]

[0091] Among them, the amplitude of G(s) can be expressed as:

[0092]

[0093] In the formula, is the open-loop cut-off frequency.

[0094] In this embodiment, the cutoff frequency of the bandpass filter is determined according to the low-frequency vibration frequency component, the center frequency of the bandpass filter is determined according to the cutoff frequency, and the bandpass filter is established according to the center frequency, thereby separating the low-frequency oscillation frequency component in the motor current to obtain the dq-axis low-frequency oscillation frequency current.

[0095] Based on the second embodiment of the present application, in the third embodiment of the present application, the same or similar contents as those of the second embodiment can be referred to the above introduction, and will not be repeated in the following. Figure 3 , Figure 3 This is a flow chart of a third embodiment of the method for suppressing low-frequency oscillation of motor current proposed in an embodiment of the present application.

[0096] Considering the PI regulation based on the current difference, in order to determine the compensation voltage vector, such as Figure 3 As shown, in this embodiment, step S40 specifically includes:

[0097] Step S41: Perform PI regulation according to the current difference and determine the PI regulation coefficient.

[0098] It should be noted that the PI adjustment coefficient includes the proportional adjustment parameter K p and integral adjustment parameter K i When performing PI adjustment, the trial and error method can be used, or it can be set according to the actual situation. This embodiment does not limit it. For example: K p =3.024 and K i =210, K p =4.08 and K i =210.

[0099] Step S42: Determine the compensation voltage vector according to the PI adjustment coefficient and the current difference.

[0100] It should be noted that the compensation voltage vector is used to compensate the voltage vector u d 、u q Optimize and offset the voltage deviation caused by bus voltage fluctuation.

[0101] In this embodiment, PI regulation is performed according to the current difference, and the PI regulation coefficient is determined. The compensation voltage vector is determined according to the PI regulation coefficient and the current difference. The compensation voltage vector is used to adjust the voltage vector u d 、u q Optimization is performed to offset the voltage deviation caused by bus voltage fluctuations, eliminate low-frequency oscillations of motor current, and improve the robustness and dynamic performance of the system.

[0102] Based on the third embodiment of the present application, in the fourth embodiment of the present application, the same or similar contents as those in the third embodiment can refer to the above description, and will not be repeated in the following. Figure 4 , Figure 4 This is a flow chart of a fourth embodiment of the method for suppressing low-frequency oscillation of motor current proposed in an embodiment of the present application.

[0103] Considering how to determine the PI adjustment parameters, such as Figure 4 As shown, in this embodiment, the step S41 specifically includes:

[0104] Step S411: Perform PI adjustment according to the current error.

[0105] Step S412: Determine PI adjustment parameters by establishing a mathematical model.

[0106] It should be noted that the proportional adjustment parameter K p and integral adjustment parameter K i The formula can be expressed as:

[0107]

[0108] Where R is the coefficient, open loop cutoff frequency The scope of determination is:

[0109]

[0110] Where P is the number of pole pairs, n is max is the maximum speed, T s is the control period, phase margin The formula can be expressed as:

[0111]

[0112] In the formula, the following conditions need to be met:

[0113]

[0114] In this embodiment, PI regulation is performed according to the current error, and a mathematical model is established to determine the PI regulation parameters, thereby determining the compensation voltage vector to eliminate the low-frequency oscillation of the motor current and improve the robustness and dynamic performance of the system.

[0115] It should be noted that if Figure 8 to Figure 11 As shown, Figure 8 Because the low-frequency oscillation suppression strategy of the present invention is not adopted, the motor current waveform is given at a speed of 5400r / min. At this time, the overall profile of the motor current fluctuates periodically, that is, there is an obvious low-frequency oscillation phenomenon. The positive peak value of the motor current fluctuates in the range of 19.9A to 21.4A, and the negative peak value fluctuates in the range of -21.4A to -19.8A. The fluctuation range is large and the current is not stable. Fig. 9 Because the low-frequency oscillation suppression strategy of the present invention is not adopted, the motor current harmonics have obvious low-frequency oscillation phenomenon at a given speed of 5400r / min, with a frequency of about 30Hz. At this speed, the motor current has a large content of low-frequency harmonics near 30Hz. Fig.10 In order to adopt the low-frequency oscillation suppression strategy of the present invention, the motor current waveform is given at a speed of 5400r / min. The overall profile of the motor current is relatively smooth, the positive peak current fluctuation range is between 20.8A and 21.3A, and the negative peak current fluctuation range is between -20.8 and -21.4A, with no obvious fluctuation. Fig.11In order to adopt the low-frequency oscillation suppression strategy of the present invention, when the given speed is 5400r / min, the low-frequency harmonic content near 30Hz in the motor current is greatly reduced, and the low-frequency harmonics are effectively suppressed. Comparing before and after the low-frequency oscillation suppression strategy of the present invention is adopted, the positive peak fluctuation amplitude of the motor current decreases from 1.5A to 0.5A, the negative peak fluctuation amplitude decreases from 1.6A to 0.6A, and the harmonic content near 30Hz decreases from 2.49% to 0.62%, proving that the proposed low-frequency oscillation suppression strategy is effective under 5400r / min working conditions.

[0116] It should be noted that if Figure 12 to Figure 15 As shown, Fig.12 Because the low-frequency oscillation suppression strategy of the present invention is not adopted, the motor current waveform is given at a speed of 5700r / min. At this time, the overall profile of the motor current fluctuates periodically, that is, there is an obvious low-frequency oscillation phenomenon. The positive peak value of the motor current fluctuates in the range of 20.9A to 22.7A, and the negative peak value fluctuates in the range of -21A to -22.7A. The fluctuation range is large and the current is not stable. Fig.13 Because the low-frequency oscillation suppression strategy of the present invention is not adopted, when the given speed is 5700r / min, the motor current harmonics have obvious low-frequency oscillation phenomenon, with a frequency of about 15Hz. At this speed, the motor current has a large content of low-frequency harmonics near 15Hz. Fig.14 After adopting the low-frequency oscillation suppression strategy of the present invention, the motor current waveform is given at a speed of 5700r / min. The overall profile of the motor current is relatively smooth, the positive peak current fluctuation range is between 21.7A and 22.7A, and the negative peak current fluctuation range is between -21.8 and -22.6A, and the fluctuation amplitude is significantly reduced. Fig.15 After adopting the low-frequency oscillation suppression strategy of the present invention, the low-frequency harmonic content near 15Hz in the motor current is greatly reduced when the given speed is 5700r / min, and the low-frequency harmonics are effectively suppressed. Comparing before and after adopting the low-frequency oscillation suppression strategy of the present invention, the positive peak fluctuation amplitude of the motor current drops from 1.8A to 1A, the negative peak fluctuation amplitude drops from 1.7A to 0.9A, and the harmonic content near 15Hz drops from 2.5% to 0.7%, proving that the proposed low-frequency oscillation suppression strategy still has significant effects under 5700r / min working conditions.

[0117] This application also provides a motor current low-frequency oscillation suppression device, please refer to Figure 5 , Figure 5 This is a schematic diagram of the module structure of the motor current low-frequency oscillation suppression device according to an embodiment of the present application, and the device includes:

[0118] A determination module 10, for determining a low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency;

[0119] A separation module 20 is used to separate the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain a dq-axis low-frequency oscillation frequency current;

[0120] A difference module 30, configured to determine a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current;

[0121] A regulating module 40, configured to perform PI regulation according to the current difference and determine a compensation voltage vector;

[0122] The compensation module 50 is used to adjust the driving voltage of the motor using the compensation voltage vector.

[0123] The present application also proposes an electrolytic capacitor-free driving system, which includes the motor current low-frequency oscillation suppression method as described above.

[0124] The present application also proposes a motor, which includes the motor current low-frequency oscillation suppression method as described above.

[0125] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A method for suppressing low-frequency oscillation of motor current, It is characterized in that The method is applied to a non-electrolytic capacitor drive system, and the motor current low-frequency oscillation suppression method comprises: Determine the low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency; The low-frequency oscillation frequency component in the motor current is separated by a band-pass filter to obtain the dq-axis low-frequency oscillation frequency current; Determining a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current; Performing PI regulation according to the current difference and determining a compensation voltage vector; The drive voltage of the motor is adjusted using the compensation voltage vector.

2. The method for suppressing low-frequency oscillation of motor current according to claim 1, It is characterized in that Before the step of separating the low-frequency oscillation frequency component in the motor current by a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current, the method further includes: Determine the cutoff frequency of the bandpass filter according to the low-frequency vibration frequency component; According to the cut-off frequency, determine the center frequency of the bandpass filter; Create a bandpass filter based on the center frequency.

3. The method for suppressing low-frequency oscillation of motor current according to claim 1, It is characterized in that The step of performing PI regulation according to the current difference and determining the compensation voltage vector specifically includes: According to the current difference, PI regulation is performed and the PI regulation coefficient is determined; The compensation voltage vector is determined according to the PI adjustment coefficient and the current difference.

4. The method for suppressing low-frequency oscillation of motor current as claimed in claim 3, It is characterized in that The step of performing PI regulation according to the current difference and determining the PI regulation coefficient specifically includes: Perform PI adjustment based on current error; By establishing a mathematical model, the PI adjustment parameters are determined.

5. A device for suppressing low-frequency oscillation of motor current, It is characterized in that The device comprises: A determination module, used to determine the low-frequency oscillation frequency component in the motor current according to the motor voltage fundamental frequency and the bus voltage fluctuation frequency; A separation module, used for separating the low-frequency oscillation frequency component in the motor current through a bandpass filter to obtain the dq-axis low-frequency oscillation frequency current; A difference module, used to determine a current difference according to the dq-axis low-frequency oscillation frequency current and a preset dq-axis low-frequency oscillation frequency current; A regulating module, used for performing PI regulation according to the current difference and determining a compensation voltage vector; The compensation module is used to adjust the driving voltage of the motor using the compensation voltage vector.

6. A drive system without electrolytic capacitor, It is characterized in that The electrolytic capacitor-free drive system includes the motor current low-frequency oscillation suppression method according to any one of claims 1 to 4.

7. A motor, It is characterized in that The motor includes the motor current low-frequency oscillation suppression method according to any one of claims 1 to 4.

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