Harmonic current suppression method of single inverter parallel drive asymmetric impedance 2*3 phase motor

Abstract

The invention belongs to the technical field of motors, and particularly relates to a harmonic current suppression method of a single inverter parallel drive asymmetric impedance 2 * 3 phase motor, in a motor drive system, a control current is the total phase current of two modules; the harmonic current suppression method comprises the following steps: firstly, carrying out Clarke conversion on a total phase current collected by three current sensors of a 2 * 3-phase motor to obtain a current i alpha beta under a two-phase static coordinate system; the current is composed of a positive sequence component and a negative sequence component; analyzing a negative sequence current coefficient from the i alpha beta current through Park conversion, and further obtaining positive and negative sequence d-q axis current components; through analysis, effective suppression of a d-q axis negative sequence component can be realized by constraining a negative sequence d axis current component to be 0; and finally, effective tracking and closed-loop control of the current are realized by adopting a PR controller, and the harmonic current is suppressed. According to the invention, control is carried out in a driving mode under the condition of asymmetric impedance so as to suppress generation of harmonic current, torque ripple and loss are effectively reduced, and the operation performance of a motor driving system is improved.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance. Background Technology

[0002] Compared to traditional three-phase permanent magnet synchronous motors, multi-phase three-phase permanent magnet synchronous motors not only utilize mature three-phase permanent magnet synchronous motor drive technology but also improve the drive system's fault-tolerant operation capability. Therefore, they have received widespread attention in aerospace, rail transportation, and marine propulsion fields. However, the traditional drive method for multi-phase three-phase motors involves multiple sets of three-phase inverters driving independently, resulting in problems such as large driver size, high cost, and high control complexity. To solve this problem and improve the space utilization of the drive system, a drive method using a single set of three-phase inverters (referred to as "single inverter") connected in parallel to drive multi-phase three-phase motors is adopted.

[0003] Due to factors such as varying motor lead lengths, uneven stator temperature rise, manufacturing tolerances, and winding faults, the resistance and inductance of each phase of the motor are not entirely consistent. Therefore, asymmetrical impedance is a common problem in motor drive systems, mainly including unbalanced resistance, self-inductance, and mutual inductance. Asymmetrical impedance leads to phase current imbalance (in... dq (This manifests as harmonic current components in the coordinate system), leading to increased motor torque ripple and losses. Furthermore, the parallel drive method of single inverters exacerbates the imbalance. The parameter imbalance in multi-phase three-phase motors primarily stems from winding asymmetry between modules, three-phase winding asymmetry within modules, and inverter asymmetry. Additionally, when a stator winding fault occurs, current imbalance will occur in each module to ensure motor output capacity, resulting in asymmetry in self-inductance and mutual inductance. To improve motor performance under unbalanced conditions, it is necessary to study harmonic current suppression methods under asymmetrical impedance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance, in order to solve the technical problem in the prior art where the asymmetry of the motor's self-inductance and mutual inductance causes asymmetrical impedance and further leads to phase current imbalance, resulting in harmonic currents.

[0005] The method for suppressing harmonic currents in a 2×3 phase motor with asymmetrical impedance driven by a single inverter in parallel comprises two modules, Module I and Module II, which are driven by a single inverter in parallel. In the motor drive system, the control current is the total phase current of both modules. The harmonic current suppression method first transforms the total phase current collected by three current sensors of the 2×3 phase motor into the current in a two-phase stationary coordinate system using Clarke transformation.i αβ The current consists of two parts: a positive-sequence component and a negative-sequence component; then, it is transformed by Park from... i αβ The negative sequence current coefficient is analyzed from the current to obtain the positive and negative sequence currents. dq Axis current components; analysis yields results that can pass through negative sequence current components. d The shaft current component is constrained to 0 to achieve dq Effective suppression of the negative sequence component of the axis; finally, a PR controller is used to achieve effective current tracking and closed-loop control, suppressing harmonic current.

[0006] Preferably, the harmonic current suppression method includes the following steps.

[0007] Step 1: Phase current signal acquired by the current sensor i abc The Clacke transformation converts the phase currents into currents in a two-phase stationary coordinate system. i αβ Due to the influence of asymmetrical impedance, the current i αβ It contains positive sequence current components i αβ + and negative sequence current components i αβ - .

[0008] Step 2: Convert the current containing positive and negative sequence current components. i αβ After Park transformation, the current is converted into a two-phase rotating coordinate system. i dq Current i dq Including DC component i dq + and pulsation component i dq - The pulsating component is a harmonic component.

[0009] Step 3: Analyze and separate the current i αβ The coefficients of the positive and negative sequence current components are obtained. i d - Harmonic component coefficients of electric current.

[0010] Step 4: d The reference values ​​for both the DC component and pulsation of the shaft current are set to 0. qThe reference value for shaft current is the output of the speed loop. The difference between the given value and the actual value is calculated, and the PR controller is used to perform closed-loop control of the current.

[0011] Step 5: Calculate the corresponding output value from the PR controller. d shaft voltage and q The shaft voltage is obtained, and the two-phase rotating coordinate system is used to obtain the shaft voltage. dq shaft voltage u dq .

[0012] Step 6: dq axis voltage u dq The αβ axis voltage is obtained through inverse Park transformation. This voltage is used as the input for SVPWM modulation to generate 6 PWM signals, thereby achieving effective driving of the motor.

[0013] Preferably, step 1 includes the following steps.

[0014] Step 1.1: Process the phase current signal acquired by the current sensor. i abc Perform Clacke transformation; considering phase current imbalance, construct an asymmetric impedance 2×3 phase motor. α , β The expression for the shaft current value.

[0015] Step 1.2, Build α-β The expression for the total current in the coordinate system is used for precise tracking control.

[0016] Step 1.3: Analyze the impact of winding structure asymmetry on current in a 2×3 phase surface-mounted permanent magnet synchronous motor.

[0017] Preferably, in step 1.1, the two modules α , β The shaft current value is expressed as:

[0018] in i αi , i βi These are Module I and Module II, respectively. α , β shaft current value, i =1,2, k 1~ k 4 represents the corresponding coefficients for the positive and negative sequence currents of the module, reflecting the asymmetry of the motor impedance. θ It is an electrical angle. I m Electricity is the current amplitude.

[0019] In step 1.2, α-βThe overall current expression in the coordinate system is: .

[0020] In step 1.3, through coefficients k 1~ k Different values ​​of 4 reflect various situations of asymmetrical impedance 2×3 phase motors, and determine the generation of harmonic currents.

[0021] Preferably, in step 1.3, the four types of cases are included.

[0022] 1) k 1≠ k 3, k 2=0, k 4≠0 indicates that the three-phase windings in module I are balanced, while those in module II are unbalanced.

[0023] 2) k 1≠ k 3, k 2≠0, k 4=0 indicates that the three-phase windings in module II are balanced, while there is an imbalance in module I.

[0024] 3) k 1≠ k 3, k 2= k 4=0 indicates that the windings within each module are balanced, but there is an imbalance between modules.

[0025] 4) k 1= k 3, k 2= k 4≠0 indicates that the two modules have the same imbalance.

[0026] Only in case 3) is there no negative sequence current component; all other cases will generate harmonic currents.

[0027] Preferably, step 2 specifically includes: α-β The total current in the coordinate system is transformed by the Park transformation to... dq In the coordinate system, the resulting expression is:

[0028] The positive sequence current and negative sequence current in the formula are dq In the coordinate system, it is converted into DC component and pulsating component.

[0029] Preferably, step 3 involves the following steps.

[0030] Step 3.1, according to α-βThe expression for the total current in the coordinate system is given, and the current coefficient is calculated.

[0031] Step 3.2: Substitute the formula for the current coefficient into the expression obtained from the Park transformation in Step 2 to obtain the positive and negative order. dq The expression for shaft current.

[0032] The analysis showed that... d If the negative sequence component of the shaft current is controlled to be 0, then q The negative sequence component of the shaft current is also 0, thus achieving the purpose of suppressing harmonic currents.

[0033] Preferably, in step 3.1, α-β The expression for the total current in the coordinate system is as follows: .

[0034] In step 3.2, the positive and negative order dq The expression for shaft current is as follows: .

[0035] Preferably, in step 5, the positive and negative sequences are... d The error values ​​of the shaft current are tracked by the PR controller, and the output values ​​are summed to obtain the total error. d shaft voltage; and q shaft voltage is q The error value of the shaft current is the output value after processing by the PR controller; the two are combined to obtain... dq shaft voltage u dq .

[0036] Preferably, the two modules are in-phase, using fractional slot concentrated windings and star connection, with each module having an independent neutral point.

[0037] The technical advantages of this invention are as follows: This invention controls the driving mode of a 2×3 phase motor driven by a single inverter in parallel under asymmetrical impedance conditions to suppress the generation of harmonic currents, achieving good suppression effects, effectively reducing torque ripple and losses, and improving the operating performance of the motor drive system. Furthermore, this invention enables the effective driving of a 2×3 phase surface-mount permanent magnet synchronous motor through a single three-phase inverter module, reducing the size, cost, and control complexity of the 2×3 phase motor controller, thus improving the cost-effectiveness of the driver while improving motor operating performance. In addition, this invention is effective in addressing both resistance mismatch and inductance mismatch problems under asymmetrical impedance. After adopting this invention, the torque ripple of the corresponding motor is significantly suppressed, thereby improving the operating performance of the drive system. Attached Figure Description

[0038] Figure 1Wiring diagram for parallel driving of a 2×3 phase surface-mounted permanent magnet synchronous motor using a single inverter of the present invention. Figure 2 This is a control block diagram for applying the present invention to suppress harmonic currents.

[0039] Figure 3 The waveforms of the phase current of module I under normal motor conditions and resistance mismatch are shown in this embodiment of the invention.

[0040] Figure 4 The waveforms of the phase current of module II under normal motor conditions and resistance mismatch are shown in this embodiment of the invention.

[0041] Figure 5 The waveforms of speed and torque under normal motor conditions and resistance mismatch are shown in the embodiments of the present invention.

[0042] Figure 6 The waveforms of the phase current of module I under normal motor conditions and inductor mismatch are shown in this embodiment of the invention.

[0043] Figure 7 The waveforms of the phase current of module II under normal motor conditions and inductor mismatch are shown in this embodiment of the invention.

[0044] Figure 8 The waveforms of speed and torque under normal motor conditions and inductor mismatch are shown in the embodiments of the present invention.

[0045] Figure 9 This is the torque waveform of the motor before and after employing a harmonic current suppression strategy under resistance mismatch in an embodiment of the present invention.

[0046] Figure 10 This is the torque waveform of the motor before and after adopting a harmonic current suppression strategy under inductor mismatch in an embodiment of the present invention. Detailed Implementation

[0047] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0048] like Figures 1-10 As shown, in the 2×3 phase motor of this invention, the stator windings are of the same phase structure, with two sets of three-phase windings defined as a1b1c1 and a2b2c2, where there is no phase difference between corresponding phases. Therefore, the stator windings are divided into two modules, Module I and Module II. To reduce the influence of mutual inductance between modules, fractional-slot concentrated windings are used. The motor windings are connected in a star configuration, with each module having an independent neutral point. Furthermore, this motor is a surface-mount motor, therefore it only has permanent magnet torque. To ensure maximum operating efficiency, [the following is used]. i d=0 control strategy. In terms of control, for this 2×3 phase surface-mounted permanent magnet synchronous motor, a single inverter in parallel drive is used, thereby reducing control complexity, controller cost, and size. Therefore, the control current in the motor drive system is the total current of the two modules, rather than the current of a single module.

[0049] This invention provides a method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance, comprising the following steps.

[0050] Step 1: Phase current signal acquired by the current sensor i abc The Clacke transformation converts the phase currents into currents in a two-phase stationary coordinate system. i αβ Due to the influence of asymmetrical impedance, the current i αβ It contains positive sequence current components i αβ + and negative sequence current components i αβ - .

[0051] The specific process of step 1 includes the following steps.

[0052] Step 1.1: Process the phase current signal acquired by the current sensor. i abc Perform a Clacke transformation. Considering the phase current imbalance, construct an asymmetrical impedance 2×3 phase motor. α , β The expression for the shaft current value.

[0053] Ideally, the current possesses only a positive-sequence rotating current vector. However, when parameter imbalance occurs, the phase current is represented as a combination of positive-sequence and negative-sequence currents. The two modules (the motor stator winding module, controlled in parallel by a single inverter) α , β The shaft current value is expressed as:

[0054] in i αi , i βi These are Module I and Module II, respectively. α , β shaft current value, i =1,2, k 1~ k 4 represents the corresponding coefficients for the positive and negative sequence currents of the module, reflecting the asymmetry of the motor impedance. θIt is an electrical angle. I m Electricity is the current amplitude. Ideally... k 1= k 3=1 and k 2= k 4=0.

[0055] Step 1.2, Build α-β The expression for the total current in the coordinate system is used for precise tracking control.

[0056] Because of the drive method of a single inverter, the current loop cannot directly control the current of each module; it can only guarantee the overall current. dq Precise tracking of shaft current. α-β The overall current expression in the coordinate system is: .

[0057] Step 1.3: Analyze the impact of winding structure asymmetry on current in a 2×3 phase surface-mounted permanent magnet synchronous motor.

[0058] pass k 1. k 2. k 3 and k Different values ​​of 4 can reflect the impact of winding structure asymmetry on the current of a 2×3 phase surface-mounted permanent magnet synchronous motor. These values ​​are divided into the following four categories: 1) k 1≠ k 3, k 2=0, k 4≠0 indicates that the three-phase windings in module I are balanced, while those in module II are unbalanced.

[0059] 2) k 1≠ k 3, k 2≠0, k 4=0 indicates that the three-phase windings in module II are balanced, while there is an imbalance in module I.

[0060] 3) k 1≠ k 3, k 2= k 4=0 indicates that the windings inside each module are balanced, but there is an imbalance between modules, that is, the current amplitudes of the two modules are not equal.

[0061] 4) k 1= k 3, k 2= k 4≠0 indicates that the two modules have the same imbalance.

[0062] Of these, only case 3) lacks a negative sequence current component; all other cases generate harmonic currents. In practical control systems, the asymmetry of the winding structure can be considered a combination of the above cases.

[0063] Step 2: Convert the current containing positive and negative sequence current components. i αβ After Park transformation, the current is converted into a two-phase rotating coordinate system. i dq In addition to the DC component, this current also contains a pulsating component, the DC component being... i dq + The pulsating component is i dq - .

[0064] The specific process of step 2 includes: […]. α-β The total current in the coordinate system is transformed by the Park transformation to... dq In the coordinate system, the resulting expression is:

[0065] The positive sequence current and negative sequence current in the formula are dq In the coordinate system, it is converted into DC component and pulsating component, the pulsating component being the harmonic component.

[0066] Step 3: Analyze and separate the current i αβ The coefficients of the positive and negative sequence current components are obtained. i d - Harmonic component coefficients of electric current.

[0067] The specific process of step 3 includes the following steps.

[0068] Step 3.1, according to α-β The overall current expression in the coordinate system, and the calculation formula for the current coefficient, are as follows: .

[0069] Step 3.2: Substitute the formula for the current coefficient into the expression obtained from the Park transformation in Step 2 to obtain the positive and negative order. dq The expression for shaft current: .

[0070] As can be seen from the above expression, it is only necessary to... d If the negative sequence component of the shaft current is controlled to be 0, then q The negative sequence component of the shaft current is also 0, thereby achieving the purpose of suppressing harmonic currents.

[0071] Step 4: d The reference values ​​for both the DC component and the pulsating component of the shaft current are set to 0. q The reference value for shaft current is the output of the speed loop. The difference between the given value and the actual value is calculated, and the PR controller is used to perform closed-loop control of the current.

[0072] Step 5: Calculate the corresponding output value from the PR controller. d shaft voltage and q The shaft voltage is obtained, and the two-phase rotating coordinate system is used to obtain the shaft voltage. dq shaft voltage u dq .

[0073] This step will sort the positive and negative numbers. d The error values ​​of the shaft current are tracked by the PR controller, and the output values ​​are summed to obtain the total error. d shaft voltage; and q shaft voltage is q The error value of the shaft current is the output value after processing by the PR controller. The two are combined to obtain... dq shaft voltage u dq .

[0074] Step 6: dq shaft voltage u dq Obtained through inverse Park transform αβ The shaft voltage, which serves as the input for SVPWM modulation, generates six PWM signals to effectively drive the motor.

[0075] In a specific embodiment, the parameters of the corresponding 2×3 phase surface-mounted permanent magnet synchronous motor are shown in Table 1.

[0076] Table 1: Parameter Table of 2×3 Phase Surface-Mounted Permanent Magnet Synchronous Motor

[0077] In this embodiment, the given speed is 600 r / min and the load is 16 N•m. When the motor operates under normal and asymmetrical impedance conditions (mismatched operation) without compensation measures, the phase current waveforms of the two modules (e.g.) Figure 3 , Figure 4 , Figure 6 , Figure 7 ) and speed and torque waveforms (such as Figure 5 , Figure 8 )like Figures 3-8 As shown. During normal operation, the parameters of the two modules are the same; Figure 3 , Figure 4 , Figure 5 During mismatch operation, the resistance of phase b2 in module II increases by 0.2Ω, and the resistance of phase c2 increases by 0.5Ω. Figure 6 , Figure 7 , Figure 8 During mismatch operation, the inductance of phase b2 in module II increases by 1 mH, and the inductance of phase c2 increases by 2 mH. It can be seen that under normal operation, the phase current amplitudes of the two modules are equal, and the torque and speed ripple are small. However, under mismatch operation, both resistance and inductance mismatch will cause an increase in torque ripple. Furthermore, due to the single-inverter drive method, even if module I does not experience mismatch, the three-phase currents still become unbalanced, and the torque and speed ripple increase.

[0078] To address the issue of mismatched operation, the harmonic current suppression method provided in this invention is applied. First, the total phase current collected by the three current sensors of the 2×3 phase surface-mounted permanent magnet synchronous motor is transformed by Clarke to obtain the current in the two-phase stationary coordinate system. i αβ The current consists of two parts: a positive-sequence component and a negative-sequence component; then, it is transformed by Park from... i αβ The negative sequence current coefficient is analyzed from the current to obtain the positive and negative sequence currents. dq Axis current components; analysis yields results that can pass through negative sequence current components. d The shaft current component is constrained to 0 to achieve dq Effective suppression of the negative sequence component of the axis; finally, a PR controller is used to achieve effective current tracking and closed-loop control, suppressing harmonic current.

[0079] Figures 9-10 This is a diagram showing the effect of applying a harmonic current suppression method to the motor before and after. In this embodiment, the given speed is 600 r / min and the load is 16 N•m. When harmonic current suppression occurs... Figure 3 , Figure 4 , Figure 5 The torque waveforms before and after applying harmonic current suppression methods to address resistor mismatch are as follows: Figure 9 As shown; when it occurs Figure 6 , Figure 7 , Figure 8 The torque waveforms before and after applying harmonic current suppression methods to address inductor mismatch are as follows: Figure 10 As shown in the figure, it can be seen that after adopting the harmonic current suppression method provided by the present invention, torque ripple is significantly suppressed, thereby improving the operating performance of the drive system.

[0080] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance in parallel, characterized in that: The stator winding module of the 2×3 phase motor is divided into two modules, namely Module I and Module II, which are driven by a single inverter in parallel. In the motor drive system, the control current is the total phase current of the two modules. The harmonic current suppression method first obtains the current in the two-phase stationary coordinate system by Clarke transformation of the total phase current collected by the three current sensors of the 2×3 phase motor. i αβ ; The current consists of two parts: a positive-sequence component and a negative-sequence component; then, it is transformed from... i αβ The negative sequence current coefficient is analyzed from the current to obtain the positive and negative sequence currents. dq Axis current components; Analysis yields results that can be obtained by passing negative orders d The shaft current component is constrained to 0 to achieve dq Effective suppression of the negative sequence component of the axis; finally, a PR controller is used to achieve effective current tracking and closed-loop control, suppressing harmonic current.

2. The method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 1, characterized in that: Includes the following steps: Step 1: Phase current signal acquired by the current sensor i abc The Clacke transformation converts the phase currents into currents in a two-phase stationary coordinate system. i αβ Due to the influence of asymmetrical impedance, the current i αβ It contains positive sequence current components i αβ + and negative sequence current components i αβ - ; Step 2: Convert the current containing positive and negative sequence current components. i αβ After Park transformation, the current is converted into a two-phase rotating coordinate system. i dq Current i dq Including DC component i dq + and pulsation component i dq - The pulsating component is a harmonic component; Step 3: Analyze and separate the current i αβ The coefficients of the positive and negative sequence current components are obtained. i d - Harmonic component coefficients of current; Step 4: d The reference values ​​for both the DC component and pulsation of the shaft current are set to 0. q The reference value for shaft current is the output of the speed loop. The difference between the given value and the actual value is calculated, and the PR controller is used to perform closed-loop control of the current. Step 5: Calculate the corresponding output value from the PR controller. d shaft voltage and q The shaft voltage is obtained, and the two-phase rotating coordinate system is used to obtain the shaft voltage. dq shaft voltage u dq ; Step 6: dq axis voltage u dq The αβ axis voltage is obtained through inverse Park transformation. This voltage is used as the input for SVPWM modulation to generate 6 PWM signals, thereby achieving effective driving of the motor.

3. The method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 2, characterized in that: Step 1 includes the following steps: Step 1.1: Process the phase current signal acquired by the current sensor. i abc Perform Clacke transformation; considering phase current imbalance, construct an asymmetric impedance 2×3 phase motor. α , β The expression for the shaft current value; Step 1.2, Build α-β The expression for the total current in the coordinate system is used for precise tracking control; Step 1.3: Analyze the impact of winding structure asymmetry on current in a 2×3 phase surface-mounted permanent magnet synchronous motor.

4. The method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 3, characterized in that: In step 1.1, the two modules α , β The shaft current value is expressed as: in i αi , i βi These are Module I and Module II, respectively. α , β shaft current value, i =1,2, k 1~ k 4 represents the corresponding coefficients for the positive and negative sequence currents of the module, reflecting the asymmetry of the motor impedance. θ It is an electrical angle. I m Electricity is the amplitude of current; In step 1.2, α-β The overall current expression in the coordinate system is: ； In step 1.3, through coefficients k 1~ k Different values ​​of 4 reflect various situations of asymmetrical impedance 2×3 phase motors, and determine the generation of harmonic currents.

5. The method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 4, characterized in that: In step 1.3, the four categories include: 1) k 1≠ k 3, k 2=0, k 4≠0 indicates that the three-phase windings in module I are balanced, while those in module II are unbalanced; 2) k 1≠ k 3, k 2≠0, k 4=0 indicates that the three-phase windings in module II are balanced, while there is an imbalance in module I; 3) k 1≠ k 3, k 2= k 4=0 indicates that the windings within each module are balanced, but there is an imbalance between modules; 4) k 1= k 3, k 2= k 4≠0 indicates that the two modules have the same imbalance. Only in case 3) is there no negative sequence current component; all other cases will generate harmonic currents.

6. The method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 5, characterized in that: Step 2 includes the following specific steps: α-β The total current in the coordinate system is transformed by the Park transformation to... dq In the coordinate system, the resulting expression is: The positive sequence current and negative sequence current in the formula are dq In the coordinate system, it is converted into DC component and pulsating component.

7. A method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance in parallel, as described in claim 6, characterized in that: Step 3: The following steps: Step 3.1, according to α-β The expression for the total current in the coordinate system is given, and the current coefficient is calculated. Step 3.2: Substitute the formula for the current coefficient into the expression obtained from the Park transformation in Step 2 to obtain the positive and negative order. dq The expression for shaft current; The analysis showed that... d If the negative sequence component of the shaft current is controlled to be 0, then q The negative sequence component of the shaft current is also 0, thus achieving the purpose of suppressing harmonic currents.

8. A method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 7, characterized in that: In step 3.1, α-β The expression for the total current in the coordinate system is as follows: ； In step 3.2, the positive and negative order dq The expression for shaft current is as follows: 。 9. A method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 2, characterized in that: In step 5, the positive and negative sequences are... d The error values ​​of the shaft current are tracked by the PR controller, and the output values ​​are summed to obtain the total error. d shaft voltage; and q shaft voltage is q The output value of the shaft current error after processing by the PR controller; The combination of the two results in dq shaft voltage u dq .

10. A method for suppressing harmonic currents in a single inverter driving a 2×3 phase motor with asymmetrical impedance according to claim 1, characterized in that: The two modules are in-phase, using fractional slot concentrated windings and star connection, with each module having an independent neutral point.

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