Grid-side current harmonic suppression method and device, driving system without electrolytic capacitor and motor

Abstract

The invention discloses a grid-side current harmonic suppression method and device, a driving system without an electrolytic capacitor and a motor, and relates to the field of permanent magnet synchronous motor control, and the method comprises the steps: detecting the input admittance of a bus voltage inputted to a driving system, determining the harmonic frequency in the bus voltage needing to be suppressed according to the input admittance, and carrying out the suppression of the harmonic frequency; according to the harmonic frequency, required virtual impedance is applied to the two sides of the bus capacitor, and compensation voltage vectors corresponding to the virtual impedance are applied to the two ends of the capacitor so as to suppress the current of the harmonic frequency. Compared with a traditional motor driving scheme using an electrolytic capacitor, the method is applied to a non-electrolytic capacitor driving system, and the impedance of the driving system to specific frequency harmonics is increased by applying virtual impedance to the two ends of the capacitor, so that the grid-side current harmonics are reduced, and the robustness and dynamic performance of the system are improved.

Description

Technical Field

[0001] The present application relates to the field of permanent magnet synchronous motor control, and in particular to a grid-side current harmonic suppression method, device, electrolytic capacitor-free drive system, and 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] 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. This results in the presence of abundant harmonics of six times the power supply frequency in the DC bus current, which makes the total harmonic distortion rate of the input (grid side) current higher, affecting the power quality on the input side (grid side). Summary of the invention

[0004] The main purpose of the present application is to provide a grid-side current harmonic suppression method, device, electrolytic capacitor-free drive system and motor, aiming to solve the technical problem that the capacitance value of the DC bus in the electrolytic capacitor-free drive system is significantly reduced, resulting in the presence of abundant harmonics of six times the power supply frequency in the DC bus current, thereby making the total harmonic distortion rate of the input (grid side) current high, affecting the input side (grid side) power quality.

[0005] To achieve the above object, the present application provides a method for suppressing grid-side current harmonics, the method comprising:

[0006] Detect the input admittance of the bus voltage input to the drive system;

[0007] Determining the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance;

[0008] Applying required virtual impedance on both sides of the bus capacitor according to the harmonic frequency;

[0009] A compensation voltage vector corresponding to the virtual impedance is applied across the capacitor to suppress the current at the harmonic frequency.

[0010] Optionally, after the step of detecting the input admittance of the bus voltage input to the drive system, the method further includes:

[0011] Conduct harmonic characteristic analysis on bus current;

[0012] Determine the harmonic distortion rate constant according to the preset multiple frequency component amplitude in the bus current;

[0013] The total harmonic distortion rate of the grid-side current is determined based on the bus current and the harmonic distortion rate constant.

[0014] Optionally, the step of applying required virtual impedance on both sides of the bus capacitor according to the harmonic frequency specifically includes:

[0015] Separate the harmonic frequencies in the bus voltage by using a bandpass filter, and connect virtual impedances in parallel on both sides of the bus capacitor;

[0016] According to the virtual impedance, the characteristics of the driving system are determined in various styles;

[0017] Under the preset stability condition, the virtual impedance required by the drive system is determined according to the various characteristics of the drive system.

[0018] Optionally, after the step of separating the harmonic frequency in the bus voltage by a bandpass filter and connecting a virtual impedance in parallel on both sides of the bus capacitor, the step further includes:

[0019] Determine the transfer function of the bandpass filter;

[0020] Determining a state equation of a bandpass filter according to the transfer function;

[0021] The bus voltage harmonic amplitude is obtained by discretizing the state equation.

[0022] Optionally, before the step of applying a compensation voltage vector corresponding to the virtual impedance across the capacitor to suppress the current at the harmonic frequency, the step further includes:

[0023] Determining virtual impedance power according to the bus voltage harmonic amplitude and virtual impedance;

[0024] According to the virtual impedance power, the virtual impedance current is determined;

[0025] According to the virtual impedance current, a compensation voltage vector is determined.

[0026] In addition, to achieve the above-mentioned purpose, the present application also proposes a grid-side current harmonic suppression device, the device comprising:

[0027] A detection module, used for detecting the input admittance of the bus voltage input to the drive system;

[0028] A suppression module, used for determining the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance;

[0029] An impedance module, used for applying a required virtual impedance on both sides of the bus capacitor according to the harmonic frequency;

[0030] The compensation module is used to apply a compensation voltage vector corresponding to the virtual impedance across the capacitor to suppress the current of the harmonic frequency.

[0031] In addition, to achieve the above-mentioned purpose, the present application also proposes an electrolytic capacitor-free drive system, and the electrolytic capacitor-free drive system includes the grid-side current harmonic suppression method as described above.

[0032] In addition, to achieve the above-mentioned purpose, the present application also proposes a motor, which includes the grid-side current harmonic suppression method as described above.

[0033] One or more technical solutions proposed in this application have at least the following effects:

[0034] In the present application, the controller of the electrolytic capacitor-free drive system detects the input admittance of the bus voltage input to the drive system, and determines the need to suppress the harmonic frequency in the bus voltage based on the input admittance, applies the required virtual impedance on both sides of the bus capacitor according to the harmonic frequency, and applies the compensation voltage vector corresponding to the virtual impedance at both ends of the capacitor to suppress the current of the harmonic frequency. Compared with the traditional motor drive solution using electrolytic capacitors, the present application is applied to the electrolytic capacitor-free drive system, and increases the impedance of the drive system to the harmonics of a specific frequency by applying virtual impedance at both ends of the capacitor, thereby reducing the grid-side current harmonics and improving the robustness and dynamic performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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.

[0036] Figure 1 A schematic diagram of the flow chart of the first embodiment of the grid-side current harmonic suppression method proposed in the embodiment of the present application;

[0037] Figure 2 A schematic diagram of a flow chart of a second embodiment of a grid-side current harmonic suppression method proposed in an embodiment of the present application;

[0038] Figure 3 A schematic flow chart of a third embodiment of a grid-side current harmonic suppression method proposed in an embodiment of the present application;

[0039] Figure 4 A schematic flow chart of a fourth embodiment of a grid-side current harmonic suppression method proposed in an embodiment of the present application;

[0040] Figure 5 A schematic flow chart of a fifth embodiment of a grid-side current harmonic suppression method proposed in an embodiment of the present application;

[0041] Figure 6 This is a schematic diagram of the module structure of the grid-side current harmonic suppression device according to an embodiment of the present application;

[0042] Figure 7 The overall block diagram of the application of the suppression method of this application;

[0043] Figure 8 For this application, K THD Relationship diagram with THDi;

[0044] Fig. 9 This is a complex frequency domain model diagram of the parallel virtual impedance of the electrolytic capacitor-free drive system of this application;

[0045] Fig.10 A bandpass filter is used to separate harmonics for this application;

[0046] Fig.11 This is a waveform diagram when the method of the present application is not used under 7KW working conditions;

[0047] Fig.12 This is a waveform diagram when the method of this application is used under 7KW working conditions;

[0048] Fig.13 The following is a comparison diagram of input current harmonics before and after using the method of the present application at different powers.

[0049] Description of Figure Numbers:

[0050] Label name Label name 10 Detection module 20 Inhibition Module 30 Impedance Module 40 Compensation module <![CDATA[R f ]]> Input Impedance <![CDATA[Z v ]]> Virtual Impedance

[0051] 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

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The main solution of the embodiment of the present application is: by applying virtual impedance at both ends of the capacitor, the impedance of the drive system to harmonics of a specific frequency is increased, thereby reducing the grid-side current harmonics and improving the robustness and dynamic performance of the system.

[0056] In this embodiment, for the convenience of description, the following description is made by taking the controller of the electrolytic capacitor-free driving system as the execution subject, and the controller may be an STM32 single-chip microcomputer.

[0057] The main advantage of the electrolytic capacitor-free structure is that the electrolytic capacitor is completely removed. The electrolytic capacitor in the traditional motor drive solution is no longer used. The electrolytic capacitor-free design reduces the maintenance cost of the system. In addition to the life extension and cost reduction, the electrolytic capacitor-free motor drive system also has the characteristics of high efficiency. The traditional electrolytic capacitor will produce a certain amount of energy loss 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. In addition, due to the removal of the limitations of the electrolytic capacitor, the electrolytic capacitor-free drive system has a faster response speed and can better adapt to load changes. The electrolytic capacitor-free motor drive system also has some shortcomings and limitations. Compared with the traditional motor drive system, the capacitance value of the DC bus in the electrolytic capacitor-free motor drive system is significantly reduced, eliminating the step of power factor correction, which leads to the presence of abundant harmonics of six times the power supply frequency in the DC bus current, which makes the total harmonic distortion rate of the input (grid side) current high, affecting the power quality of the input side (grid side).

[0058] The present application provides a solution, in which the controller of the electrolytic capacitor-free drive system detects the input admittance of the bus voltage input to the drive system, and determines the need to suppress the harmonic frequency in the bus voltage based on the input admittance, applies the required virtual impedance on both sides of the bus capacitor according to the harmonic frequency, and applies the compensation voltage vector corresponding to the virtual impedance at both ends of the capacitor to suppress the current of the harmonic frequency. Compared with the traditional motor drive solution using electrolytic capacitors, the present application is applied to the electrolytic capacitor-free drive system, and by applying virtual impedance at both ends of the capacitor, the impedance of the drive system to the harmonics of a specific frequency is increased, thereby reducing the grid-side current harmonics and improving the robustness and dynamic performance of the system.

[0059] Based on this, an embodiment of the present application provides a method for suppressing grid-side current harmonics.

[0060] Reference Figure 1 , Figure 1 This is a flow chart of the first embodiment of the grid-side current harmonic suppression method proposed in the embodiments of the present application.

[0061] Considering that the capacitance value of the DC bus in the electrolytic capacitor-free drive system is significantly reduced, resulting in the presence of abundant harmonics of six times the power supply frequency in the DC bus current, which makes the total harmonic distortion rate of the input (grid side) current high, affecting the power quality of the input side (grid side), and in order to suppress the grid side current harmonics, such as Figure 1 , Figure 7 and Fig. 9 As shown, the grid-side current harmonic suppression method includes steps S10 to S40:

[0062] Step S10: Detect the input admittance of the bus voltage input to the drive system.

[0063] It should be noted that the input admittance Y of the drive system g The formula is:

[0064]

[0065] Among them, C dc is the bus capacitance, L g is the grid-side inductance, R g is the grid side resistance, Y m (s) is the input admittance of the inverter (drive system), and s is a complex frequency domain variable. The parameters can be substituted into the above formula. The drive system will have a larger admittance value near a certain multiple of the power supply frequency, indicating that when there are voltage harmonics near this frequency in the DC bus voltage, significant harmonic currents will be formed in the bus current.

[0066] Step S20: determining the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance.

[0067] Step S30: applying the required virtual impedance on both sides of the bus capacitor according to the harmonic frequency.

[0068] It should be noted that a virtual impedance is connected in parallel at both ends of the bus capacitor to increase the impedance of the drive system to harmonics of a specific frequency.

[0069] Step S40: applying a compensation voltage vector corresponding to the virtual impedance across the capacitor to suppress the current of the harmonic frequency.

[0070] It should be noted that reducing the current harmonic distortion rate on the input side (grid side) is achieved by suppressing the harmonics of the bus voltage (current).

[0071] In a specific implementation, the controller of the electrolytic capacitor-free drive system detects the input admittance of the bus voltage input to the drive system, determines the need to suppress the harmonic frequency in the bus voltage based on the input admittance, applies the required virtual impedance on both sides of the bus capacitor based on the harmonic frequency, and applies a compensation voltage vector corresponding to the virtual impedance at both ends of the capacitor to suppress the current of the harmonic frequency, thereby increasing the impedance of the drive system to harmonics of a specific frequency, thereby reducing the grid-side current harmonics and improving the robustness and dynamic performance of the system.

[0072] 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 grid-side current harmonic suppression method proposed in an embodiment of the present application.

[0073] Considering the influence of the harmonics in the bus current on the total harmonic distortion rate of the grid-side current, in order to determine the total harmonic distortion rate of the grid-side current, such as Figure 2 and Figure 8 As shown, after step S10 in this embodiment, the following steps are further included:

[0074] Step S101: performing harmonic characteristic analysis on bus current.

[0075] It should be noted that the fundamental amplitude of the u-phase current is expressed as follows:

[0076]

[0077] In the formula, i dc_6 Indicates the amplitude of the 6-fold frequency component in the bus current, i dc_0 Indicates the DC component in the bus current.

[0078] Step S102: Determine the harmonic distortion rate constant according to the preset amplitude of the frequency-multiplied component in the bus current.

[0079] It should be noted that, let the harmonic distortion rate constant be K THD , which can be expressed as:

[0080]

[0081] K THD The larger the value, the greater the proportion of harmonics at 6 times the power supply frequency in the DC bus current. Conversely, K THD The smaller the value, the smaller the proportion of harmonics at 6 times the power supply frequency.

[0082] Step S103: determining the total harmonic distortion rate of the grid-side current according to the bus current and the harmonic distortion rate constant.

[0083] It should be noted that the total harmonic distortion rate of the grid-side current is THDi, which can be expressed as:

[0084]

[0085] Among them, I u is the u-phase current, I rms Effective value of input current.

[0086] In the specific implementation, the harmonic characteristics of the bus current are analyzed, and the harmonic distortion rate constant is determined according to the preset amplitude of the double frequency component in the bus current. The total harmonic distortion rate of the grid-side current is determined according to the bus current and the harmonic distortion rate constant. Therefore, the bus current harmonics are suppressed through virtual resistance, the total harmonic distortion rate of the grid-side current is reduced, and the suppression of the grid-side current harmonics is achieved.

[0087] 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 grid-side current harmonic suppression method proposed in an embodiment of the present application.

[0088] Consider applying virtual impedance across the capacitor to increase the impedance of the drive system to specific frequency harmonics, thereby reducing grid-side current harmonics and improving the robustness and dynamic performance of the system. In order to determine the virtual impedance required for the electrolytic capacitor-free drive system, such as Figure 3 and Fig.10 As shown, step S30 in this embodiment specifically includes:

[0089] Step S31: Separate the harmonic frequency in the bus voltage through a bandpass filter, and connect virtual impedance in parallel on both sides of the bus capacitor.

[0090] Step S32: Determine the driving system characteristic diversity according to the virtual impedance.

[0091] It should be noted that if Fig. 9 As shown, the system characteristic polynomial can be expressed as:

[0092]

[0093] Among them, R f is the input equivalent resistance, Z v Represents the virtual impedance connected in parallel across the capacitor, u dc_avg is the average voltage of the DC bus, P L is the load power.

[0094] Step S33: Under the preset stability condition, the virtual impedance required by the driving system is determined according to the characteristics of the driving system.

[0095] It should be noted that the preset stability condition can be the Routh–Hurwitz criterion, which can be expressed as:

[0096]

[0097] In a specific implementation, the harmonic frequencies in the bus voltage are separated by a bandpass filter, and a virtual impedance is connected in parallel on both sides of the bus capacitor. The characteristic diversity of the drive system is determined based on the virtual impedance. Under the preset stability conditions, the minimum virtual impedance that meets the stability requirements of the drive system is determined based on the characteristic diversity of the drive system, thereby increasing the impedance of the drive system to harmonics of a specific frequency, thereby reducing the grid-side current harmonics and improving the robustness and dynamic performance of the system.

[0098] 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 grid-side current harmonic suppression method proposed in an embodiment of the present application.

[0099] Considering the separation of the harmonic frequency in the bus voltage by a bandpass filter, in order to determine the bus voltage harmonic amplitude, such as Figure 4 As shown, after step S31 in this embodiment, the following steps are further included:

[0100] Step S301: Determine the transfer function of the bandpass filter.

[0101] It should be noted that the transfer function of the bandpass filter can be expressed as:

[0102]

[0103] Wherein, Q is the quality factor, w0 is the angular frequency of the voltage harmonic to be extracted by the bandpass filter, A(w0) is the gain, and w0 can be 300.

[0104] Step S302: Determine a state equation of a bandpass filter according to the transfer function.

[0105] It should be noted that the state equation of the bandpass filter can be expressed as:

[0106]

[0107] Among them, x1 and x2 are state variables of the state equation, and y is the output.

[0108] Step S303: discretize the state equation to obtain the bus voltage harmonic amplitude.

[0109] It should be noted that after the state equation is discretized, it can be expressed as:

[0110] x1=x1+T s x2

[0111]

[0112] Among them, T s is a discrete cycle, u is the input, and the STM32 tick timer can be used for time marking. The time difference between the two markings is used to get T, where the output y is u dc_6 ,u dc_6 is the amplitude of the 6-fold frequency component in the bus voltage. In this embodiment, the bus voltage harmonic amplitude can be the amplitude of the 6-fold frequency component in the bus voltage.

[0113] In a specific implementation, the transfer function of the bandpass filter is determined, and based on the transfer function, the state equation of the bandpass filter is determined. The state equation is discretized to obtain the amplitude of the 6-fold frequency component in the bus voltage, thereby suppressing the bus voltage harmonics through virtual resistance, reducing the total harmonic distortion rate of the grid-side current, and achieving suppression of the grid-side current harmonics.

[0114] Based on the fourth embodiment of the present application, in the fifth embodiment of the present application, the same or similar contents as those in the fourth embodiment can refer to the above description, and will not be repeated in the following. Figure 5 , Figure 5 This is a flow chart of the fifth embodiment of the grid-side current harmonic suppression method proposed in the embodiments of the present application.

[0115] Considering that the grid-side current harmonics are suppressed by the compensation voltage vector, in order to determine the compensation voltage vector, such as Figure 5 As shown, before step S40 shown in this embodiment, the following steps are also included:

[0116] Step S401: Determine the virtual impedance power according to the bus voltage harmonic amplitude and the virtual impedance.

[0117] It should be noted that the virtual impedance power P V , which can be expressed as:

[0118]

[0119] Among them, u dc is the bus voltage, i v is the virtual impedance current, u dc_6 It is the harmonic component of the sixth power frequency of the bus voltage.

[0120] Step S402: Determine the virtual impedance current according to the virtual impedance power.

[0121] It should be noted that the virtual impedance current i v , which can be expressed as:

[0122]

[0123] Among them, Δu dq is the compensation voltage vector (superimposed virtual impedance voltage), i dq is the original inverter (drive system) dq current, u dq is the original inverter (drive system) dq voltage.

[0124] Step S403: Determine a compensation voltage vector according to the virtual impedance current.

[0125] It should be noted that the compensation voltage vector Δu dq , which can be expressed as:

[0126]

[0127] In a specific implementation, the virtual impedance power is determined according to the bus voltage harmonic amplitude and the virtual impedance, the virtual impedance current is determined according to the virtual impedance power, and the compensation voltage vector is determined according to the virtual impedance current. The virtual impedance is connected in parallel at both ends of the capacitor by the compensation voltage to increase the impedance of the system to harmonics of a specific frequency, reduce the current harmonic distortion rate on the input side, and improve the robustness and dynamic performance of the system.

[0128] It should be noted that if Fig.11 and Fig.12 As shown, Fig.11 This is the waveform diagram when the method of this application is not used under 7KW working conditions. Fig.12 This is a waveform diagram when the method of the present application is used under 7KW working conditions. Before the method of the present application is used, the amplitude of the 5th harmonic current at the input end reaches 2.93A, while the amplitude of the 7th harmonic current is 2.93A. After the strategy is adopted, the amplitude of the 5th harmonic point current at the input end is 2.81A, while the amplitude of the 7th harmonic current is 2.43A. This shows that the harmonics of the input side current are successfully reduced to a certain extent, thereby reducing the harmonic distortion rate of the current.

[0129] It should be noted that if Fig.13 As shown, Fig.13The comparison chart of the 5th harmonic, 7th harmonic and total harmonic distortion rate of the input current under 3KW, 5KW and 7KW working conditions using the method of this application shows that the amplitudes of the 5th and 7th harmonics have decreased under three different working conditions. At the same time, the total harmonic distortion rate of the current has also been reduced from the original 63.68%, 50.79% and 44.52% to 51.48%, 41.11% and 36.37% respectively. This confirms that the scheme of this application can significantly reduce the harmonic distortion rate of the input current, thereby improving the power quality at the input end (grid side).

[0130] This application also provides a grid-side current harmonic suppression device, please refer to Figure 6 , Figure 6 This is a schematic diagram of the module structure of the grid-side current harmonic suppression device according to an embodiment of the present application, and the device includes:

[0131] A detection module 10, used to detect the input admittance of the bus voltage input to the drive system;

[0132] A suppression module 20, configured to determine the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance;

[0133] An impedance module 30, used to apply a required virtual impedance on both sides of the bus capacitor according to the harmonic frequency;

[0134] The compensation module 40 is used to apply a compensation voltage vector corresponding to the virtual impedance across the capacitor to suppress the current of the harmonic frequency.

[0135] The present application also proposes a motor, which includes the grid-side current harmonic suppression method as described above.

[0136] 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 grid-side current harmonics, characterized in that: The method is applied to a non-electrolytic capacitor drive system, and the grid-side current harmonic suppression method includes: Detect the input admittance of the bus voltage input to the drive system; Determining the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance; Applying required virtual impedance on both sides of the bus capacitor according to the harmonic frequency; A compensation voltage vector corresponding to the virtual impedance is applied across the capacitor to suppress the current at the harmonic frequency.

2. The grid-side current harmonic suppression method according to claim 1, characterized in that: After the step of detecting the input admittance of the bus voltage input to the drive system, the method further includes: Conduct harmonic characteristic analysis on bus current; Determine the harmonic distortion rate constant according to the preset multiple frequency component amplitude in the bus current; The total harmonic distortion rate of the grid-side current is determined based on the bus current and the harmonic distortion rate constant.

3. The grid-side current harmonic suppression method according to claim 1, characterized in that: The step of applying the required virtual impedance on both sides of the bus capacitor according to the harmonic frequency specifically includes: Separate the harmonic frequencies in the bus voltage by using a bandpass filter, and connect virtual impedances in parallel on both sides of the bus capacitor; According to the virtual impedance, the characteristics of the driving system are determined in various styles; Under the preset stability condition, the virtual impedance required by the drive system is determined according to the various characteristics of the drive system.

4. The grid-side current harmonic suppression method according to claim 3, characterized in that: After the step of separating the harmonic frequency in the bus voltage by a bandpass filter and connecting virtual impedance in parallel on both sides of the bus capacitor, the method further includes: Determine the transfer function of the bandpass filter; Determining a state equation of a bandpass filter according to the transfer function; The bus voltage harmonic amplitude is obtained by discretizing the state equation.

5. The grid-side current harmonic suppression method according to claim 4, characterized in that: Before the step of applying the compensation voltage vector corresponding to the virtual impedance at both ends of the capacitor to suppress the current of the harmonic frequency, the method further includes: Determining virtual impedance power according to the bus voltage harmonic amplitude and virtual impedance; According to the virtual impedance power, the virtual impedance current is determined; According to the virtual impedance current, a compensation voltage vector is determined.

6. A grid-side current harmonic suppression device, characterized in that: The device comprises: A detection module, used for detecting the input admittance of the bus voltage input to the drive system; A suppression module, used for determining the harmonic frequency in the bus voltage that needs to be suppressed according to the input admittance; An impedance module, used for applying a required virtual impedance on both sides of the bus capacitor according to the harmonic frequency; The compensation module is used to apply a compensation voltage vector corresponding to the virtual impedance across the capacitor to suppress the current of the harmonic frequency.

7. A non-electrolytic capacitor drive system, characterized in that: The electrolytic capacitor-free drive system includes the grid-side current harmonic suppression method according to any one of claims 1 to 5.

8. A motor, characterized in that: The motor includes the grid-side current harmonic suppression method according to any one of claims 1 to 5.

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