Self-excitation motor and motor control strategy based on high-frequency harmonic current phase optimization

Abstract

A self-excitation motor disclosed by the present invention comprises a rotor, a first end of the rotor is equipped with a rectification circuit, the rotor comprises a rotor iron core and a plurality of harmonic windings and excitation windings, the rotor iron core is provided with rotor teeth, and each harmonic winding and each excitation winding are respectively wound on the corresponding rotor teeth. Each harmonic winding comprises a first harmonic winding and a second harmonic winding, the winding directions of the first harmonic winding and the second harmonic winding are the same, star connection is adopted, one ends of the first harmonic winding and the second harmonic winding are connected in series in a one-to-one mode, and the other ends of the first harmonic winding and the second harmonic winding are jointly connected to form a star neutral point; the other end of each second harmonic winding is connected with the midpoint of each bridge arm in the rectifying circuit in a one-to-one manner; the winding directions of the excitation windings on every two adjacent rotor teeth are opposite, and the two ends of each excitation winding are electrically connected with the direct current output end of the rectification circuit. This induces and rectifies the current for excitation more efficiently. The invention further provides a motor control strategy based on high-frequency harmonic current phase optimization.

Description

Technical Field

[0001] This invention relates to the field of motor control, and more specifically to a self-excited synchronous motor and a control strategy based on high-frequency harmonic current phase optimization. Background Technology

[0002] A self-excited synchronous motor is a type of synchronous motor that does not require an independent DC power supply (such as an external exciter or static exciter) to provide initial excitation current to its rotor. Its working principle is as follows: by injecting a specific form of electrical signal into the stator winding of the motor itself, a current is induced in the rotor closed winding (such as damping winding, starting winding or specially designed excitation winding), thereby establishing a rotor magnetic field.

[0003] Traditional self-excitation strategies inject a high-frequency stator current independent of the fundamental wave into the stator side to generate a rotating magnetomotive force and achieve brushless excitation through rotor harmonic windings. The control strategy essentially still uses the phase logic of a three-phase system (phase difference control at 2π / 11) to generate a high-frequency magnetic field that rotates (or pulsates) at the same frequency. Because the synchronous motor rotor is not completely "synchronized" with this high-frequency magnetic field when stationary or at low speeds, the high-frequency magnetic field cuts the rotor conductors, inducing an electromotive force and generating an induced current in the rotor closed loop. This induced current generates a rotor magnetic field that interacts with the stator fundamental magnetic field, producing electromagnetic torque for starting or initial positioning, and gradually establishing an effective rotor main magnetic field, creating conditions for the motor to enter a stable operating state.

[0004] However, the drawback of the existing excitation strategy is its low excitation efficiency. Specifically, when injecting high-frequency harmonic current of the same amplitude and frequency into the stator side of the motor, the rotor excitation current generated by the existing method is significantly smaller. This essentially reflects the insufficient utilization efficiency of its high-frequency harmonic magnetic field, which fails to achieve optimal electromechanical energy conversion. As a result, it is difficult to establish a rotor magnetic field of sufficient strength under the same control cost, thereby limiting the overall performance and starting capability of the motor.

[0005] In view of this, this application has conducted in-depth research on this basis, resulting in this case. Summary of the Invention

[0006] The purpose of this invention is to provide a self-excited motor with significantly improved excitation current.

[0007] The purpose of this invention is to provide a motor control strategy based on high-frequency harmonic current phase optimization that significantly improves the excitation current.

[0008] To achieve the above objectives, the solution of the present invention is: A self-excited motor includes a motor body and a motor control system. The motor control system includes an inverter composed of eleven-phase IGBT bridge arms. The motor body includes a rotor and a stator mounted on the outside of the rotor. The stator includes a stator core and several stator windings. The first ends of each stator winding are connected together, and the second ends are respectively connected to the signal output terminals of the inverter. A circuit board with an integrated rectifier circuit is mounted on the first end of the rotor. The rotor includes a rotor core and several harmonic windings and excitation windings. The rotor core has eight rotor teeth arranged along the circumferential direction. Each harmonic winding and each excitation winding is wound around a corresponding stator core. On the rotor teeth, each of the harmonic windings is divided into two groups, corresponding to the first harmonic winding and the second harmonic winding, respectively. The winding directions of each first harmonic winding and each second harmonic winding are the same and they are connected in a star configuration. The first ends of each first harmonic winding are connected together to form a star neutral point. The first end of each second harmonic winding is connected one-to-one with the midpoint of each bridge arm in the rectifier circuit. The second ends of each first harmonic winding and each second harmonic winding are connected in series one-to-one. The winding directions of the excitation windings on adjacent rotor teeth are opposite, and the two ends of the excitation windings are electrically connected to the DC output terminals of the rectifier circuit.

[0009] The motor body is an 11-slot, 8-pole synchronous motor.

[0010] The rectifier circuit is an 8-phase diode rectifier circuit.

[0011] The stator winding is an 11-phase concentrated stator winding.

[0012] A filter capacitor is connected between the excitation winding and the rectifier circuit to suppress excitation current pulsation.

[0013] A motor control strategy based on high-frequency harmonic current phase optimization, employing the aforementioned self-excited motor, includes the following steps: Step 1: Generate a preset high-frequency harmonic current. The phase of the high-frequency harmonic current is determined according to the following steps. Step 1-1: Construct a high-frequency harmonic current control model for a multiphase self-excited motor. The high-frequency harmonic current control model is as follows: In the formula, This represents the high-frequency harmonic current of an 11-phase self-excited synchronous motor. Indicates time; This indicates the phase sequence number of the self-excited synchronous motor. =0, 1, ..., 10, respectively corresponding to the th Phase, First Phase, ..., First Mutually; Indicates the amplitude of the fundamental current. Indicates the phase of the fundamental current. Indicates the amplitude of harmonic current. Indicates the phase of the harmonic current; The phase coefficient representing the harmonic current. =1, 2, ..., 10; Step 1-2: Use the first spatial harmonic constraint condition to determine whether spatial harmonics exist in the total magnetomotive force. This first spatial harmonic constraint condition is... In the formula, Indicates the spatial harmonic order. m It can be any integer; Steps 1-3: Use the second spatial harmonic constraint condition to determine whether the spatial harmonic order in the air gap magnetic flux density is satisfied. This second spatial harmonic constraint condition is... , Represents a non-negative integer; Steps 1-4: The phase coefficients of the harmonic currents... Substituting these values ​​into the first and second spatial harmonic constraint conditions, each phase coefficient is calculated. corresponding value, Take a non-negative integer, then select The phase coefficient corresponding to the minimum value And control the phase difference between the high-frequency harmonic currents of two adjacent phases to be 2. π / 11 is used to inject the high-frequency harmonic current; Step 2: Input the high-frequency harmonic current into the motor control system. The motor control system processes the high-frequency harmonic current to generate a stator voltage setpoint, which is then superimposed on the fundamental voltage setpoint and acts together in the inverter to output a PWM signal to the stator winding of the self-excited motor.

[0014] In steps 1-2, Fourier decomposition is used to obtain the first... The magnetomotive force of the phase winding is, In the formula, Indicates the number of turns in series per phase. ; For the first The winding factor of the subharmonics, in which the lumped winding ; Indicates the first k The axial position of the phase winding, where ; Indicates the stator inscribed angle; The total magnetomotive force of the 11-phase harmonic winding is The formula for the total magnetomotive force is obtained by calculation. ; Based on the sum-to-product formula for trigonometric functions, the total magnetomotive force formula is transformed into... ; The summation term in the total magnetomotive force formula is denoted as follows: S 1. S 2. The expressions are as follows: , , In order to make S 1. S 2 is not zero. P and Must meet: and In the formula, r and s All are integers, thus obtaining the first spatial harmonic constraint condition.

[0015] In steps 1-3, the formula for calculating the air gap magnetic flux density is as follows: In the formula, Indicates the air gap magnetic flux density. Indicates air gap permeability. This indicates the rotor's mechanical position; wherein, the air gap magnetic permeability, expanded into a Fourier series, is... In the formula, This represents the DC component of the air gap permeability. For air gap permeability n The amplitude of the second harmonic component; among which... , The rotor's mechanical speed. This is the initial position of the rotor's mechanical angle; Using the product-sum formula, the specific formula for calculating the air gap magnetic flux density is as follows:

[0016] = , Due to the orthogonality of the cosine function, the integral requires that the spatial order of the air gap magnetic flux density satisfy the second spatial harmonic constraint condition.

[0017] With the above structure, the present invention has the following beneficial effects: by adopting a motor body structure with 11 slots and 8 poles, and with the 11-phase centralized stator winding design, combined with the circuit connection between the harmonic winding itself and the rectifier circuit, the current for excitation can be sensed and rectified more efficiently.

[0018] After adopting the above control strategy, the present invention has the following beneficial effects: by constructing a stator current control model and introducing spatial harmonic constraint conditions one and two, the phase coefficient of the high-frequency harmonic current is controlled. Optimization was performed to ensure that the injected high-frequency current was matched to the rotor structure and winding parameters of the motor to the greatest extent possible. This significantly improved the utilization efficiency of the high-frequency harmonic magnetic field and solved the problems of insufficient excitation current and inefficiency in traditional excitation strategies. In other words, by selecting [the appropriate excitation current]... n The phase coefficient with the smallest value And control the phase difference between the high-frequency harmonic currents of two adjacent phases to be 2. The injection of π / 11 high-frequency harmonic current can induce a larger excitation current on the rotor side when the same amplitude and frequency of high-frequency harmonic current is injected on the stator side, thus achieving optimal electromechanical energy conversion and establishing a rotor magnetic field of sufficient strength, effectively improving the overall performance and starting capability of the motor. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the motor body in this invention.

[0020] Figure 2 This is a schematic diagram of the circuit connection of the harmonic winding, excitation winding and rectifier circuit in this invention.

[0021] Figure 3 This is a cross-sectional view of the motor body in this invention.

[0022] Figure 4 This is a block diagram of the control strategy for the self-excited magneto of the present invention.

[0023] In the picture: 100-Motor body; 1-Stator core; 12-Stator winding; 2-Rotor core; 21-Harmonic winding; 22-Excitation winding; 3-Circuit board. Detailed Implementation

[0024] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0025] A self-excited motor, such as Figures 1-3 As shown, this method is applicable to multiphase self-excited synchronous motors. In this embodiment, an 11-phase, 11-slot, 8-pole synchronous motor is used as an example for illustration.

[0026] The self-excited motor includes a motor body 100 and a motor control system. The motor body 100 includes a rotor and a stator. The stator is conventionally mounted on the outside of the rotor. The stator includes a stator core 1 and 11 sets of stator windings 12. Each stator winding 12 is conventionally wound on the stator core 1. In this embodiment, each stator winding 12 together constitutes a conventional 11-phase centralized stator winding. The first ends of each stator winding 12 are connected together to form a star neutral point. The second ends of each stator winding 12 are respectively connected to the input terminals of the motor control system. The connection of each stator winding 12 follows the connection method used in existing self-excited synchronous motors, so it will not be described in detail.

[0027] The rotor described above has salient poles, and a circuit board 3 is mounted on the end of the rotor. The circuit board 3 integrates a rectifier circuit, including a rotor core 2, eight harmonic windings 21, and eight excitation windings. The rotor core 2 has eight rotor teeth arranged circumferentially. Each harmonic winding 21 and each excitation winding 22 is wound on its corresponding rotor tooth. The winding directions of the excitation windings on adjacent rotor teeth are opposite, and the two ends of each excitation winding are connected to the DC output terminal of the motor control system in a conventional manner. Each harmonic winding is divided into two groups, with four first harmonic windings and four second harmonic windings. The winding directions of each first harmonic winding and each second harmonic winding are the same, and they are connected in a star configuration. The first ends of each first harmonic winding are connected together to form a star neutral point. The first end of each second harmonic winding is connected one-to-one with the midpoint of each bridge arm in the rectifier circuit, and the second ends of each first harmonic winding and each second harmonic winding are connected one-to-one.

[0028] Furthermore, the aforementioned motor control system adopts a conventional control system found in existing self-excited synchronous motors. For example, in this embodiment, the motor control system includes a PIR regulator and an inverter. The inverter is a conventional power converter composed of eleven-phase IGBT bridge arms. The second terminals of each stator winding 12 are respectively connected to the signal output terminals of the inverter. Additionally, as... Figure 3 As shown, the motor control system here also includes a PI control system and various sensors. These sensors correspond to voltage sensors for acquiring stator phase current, voltage sensors for acquiring DC bus voltage, and speed sensors for acquiring rotor position and speed information. Since the motor control system uses conventional systems in this field, its system processing and calculations also follow conventional operations in this field (e.g., ...). Figure 3 (As shown), so it will not be described further.

[0029] Furthermore, the aforementioned rectifier circuit uses existing conventional rectifier circuits, such as the 8-phase diode rectifier circuit used in this embodiment, which includes four bridge arms.

[0030] Furthermore, in this embodiment, each of the first harmonic windings corresponds to... , , , Each second harmonic winding corresponds to the following: , , , The circuit connection between the second terminals of each first harmonic winding and each second harmonic winding is as follows: Figure 3 As shown, specifically, the first harmonic winding The second end is connected in series with the second harmonic winding. The second end, the first harmonic winding The second end is connected in series with the second harmonic winding. The second end, the first harmonic winding The second end is connected in series with the second harmonic winding. The second end, the first harmonic winding The second end is connected in series with the second harmonic winding. The second end, and the second harmonic winding , , , The first end is connected to the midpoint of the corresponding bridge arm of the rectifier circuit. In this way, the original 8 channels of the rectifier circuit are reduced to 4 channels, thereby reducing the overall conduction and switching losses of the rectifier circuit and reducing the size of the rectifier circuit.

[0031] Preferably, a filter capacitor is connected between the excitation winding and the rectifier circuit. That is, the filter capacitor It is connected in parallel between the excitation winding and the rectifier circuit to suppress the pulsation of the excitation current, thereby reducing the torque pulsation of the motor.

[0032] It should be noted that the high-frequency harmonic current can generate a high-frequency harmonic magnetomotive force even when the motor is stationary. This high-frequency harmonic magnetomotive force interacts with the air gap magnetic permeability, inducing a high-frequency magnetic flux in the air gap, which in turn induces a back electromotive force in the rotor's harmonic windings. After rectification by the 8-phase bridge rectifier circuit integrated on the rotor, the back electromotive force provides a stable DC excitation current to the excitation windings. Since the injected high-frequency harmonic current is independent of the fundamental current, this excitation method can still operate effectively under zero-speed and low-speed conditions.

[0033] This invention also provides a motor control strategy based on high-frequency harmonic current phase optimization, applicable to the aforementioned self-excited synchronous motors, such as... Figure 4 As shown, the specific steps include the following.

[0034] Step 1: Preset high-frequency harmonic current. The phase optimization of this high-frequency harmonic current is determined according to the following steps.

[0035] Step 1-1: To achieve harmonic excitation during zero-speed and low-speed operation, the high-frequency harmonic current control model for the 11-phase self-excited synchronous motor is constructed as follows: (1), In the formula, This represents the high-frequency harmonic current of an 11-phase self-excited synchronous motor. Indicates time; This indicates the phase sequence number of the self-excited synchronous motor. =0, 1, ..., 10, respectively corresponding to the th Phase, First Phase, ..., First Mutually; Indicates the amplitude of the fundamental current. Indicates the phase of the fundamental current. Indicates the amplitude of harmonic current. Indicates the phase of the harmonic current; The phase coefficient representing the harmonic current. =1, 2, ..., 10, used to adjust the phase difference of harmonic currents.

[0036] Furthermore, in formula (1), the high-frequency harmonic current is used for excitation, while the amplitude and phase of the fundamental current interact with the synchronously rotating magnetic field of the rotor generated by the high-frequency harmonic current to produce electromagnetic torque. Under the same harmonic current amplitude and phase conditions, P Different values ​​will result in different excitation current magnitudes. Therefore, in this embodiment, the phase relationship is determined in the following manner.

[0037] Step 1-2: Use the first spatial harmonic constraint condition to determine whether spatial harmonics exist in the total magnetomotive force. This first spatial harmonic constraint condition is... In the formula, Indicates the spatial harmonic order. m It can be any integer.

[0038] To elaborate, under zero-speed conditions, in formula (1) Since the fundamental current has a negligible effect on excitation, for ease of analysis, only the influence of high-frequency harmonic currents will be considered when calculating the excitation current below.

[0039] The magnetomotive force generated by a single-phase harmonic winding can be decomposed into spatial harmonics. For the stator winding, a concentrated winding is used, and the winding function is approximated as a rectangular wave. Through Fourier decomposition, the first... The magnetomotive force of the phase harmonic winding is: (2); In the formula, Indicates the first Magnetomotive force of phase harmonic winding Indicates the number of turns in series per phase. ; For the first The winding factor of the subharmonics, in which the concentrated winding ; Indicates the first k The axial position of the phase winding, where ; This represents the stator inscribed angle.

[0040] The total magnetomotive force of the 11-phase harmonic winding is: (3), where, It represents the total magnetomotive force.

[0041] Substituting the high-frequency harmonic current and formula (2) into formula (3), the total magnetomotive force formula is calculated as follows: (4).

[0042] Then, according to the sum-to-product formula for trigonometric functions, i.e., formula (5), (5), Equation (4) can be transformed into the following form based on equation (5): (6).

[0043] According to formula (6), the total magnetomotive force consists of two parts, one of which is a positive traveling wave with a spatial harmonic order of _____. The other is a reverse traveling wave, whose spatial harmonic order is... .

[0044] Let the summation term in formula (6) be . S 1. S 2. The specific expressions are as follows: (7); (8).

[0045] If you want to S 1. S 2 is not zero. P and Must meet: (9) and (10); where, r and s All are non-negative integers.

[0046] Thus, combining formulas (9) and (10), in the total magnetomotive force, as long as the following condition is met (i.e., the spatial harmonic constraint condition one is met), the spatial harmonics... Only then will it exist, that is (11).

[0047] It should be noted that the total magnetomotive force in formula (6) can be simplified to: (12), where, The sign depends on, if =11 m + P， but Take the negative sign, if =11 m P ,but Take the positive sign.

[0048] 11-slot concentrated winding, winding factor The calculation formula is: (13), where, Indicates the winding factor. Indicates pitch, Indicates the pole pitch, where the pitch ratio is... , =11 / 8, therefore the formula for calculating the winding factor is transformed into: (14).

[0049] Furthermore, in this embodiment, for example, using... P Taking 3 as an example, the existing spatial harmonic order is: Calculate the first few harmonic orders: m When = 0, = 3, -3; m When = 1, = 14,8; m When = -1, = -8, -14 (the absolute values ​​are 8 and 14), therefore, for P =3, and the main spatial harmonic orders contained in its total magnetomotive force are: =3, 8, 14, ... Other harmonics, due to not satisfying the orthogonality condition, are completely canceled out in the combined magnetomotive force of the 11-phase winding.

[0050] It is worth mentioning that the above refers to different phase coefficients. P Lower stator phase current and total magnetomotive force of harmonic winding The relationship between them.

[0051] Steps 1-3: Use the second spatial harmonic constraint condition to determine whether the spatial harmonic order in the air gap magnetic flux density is satisfied. This second spatial harmonic constraint condition is... , Represents a non-negative integer.

[0052] To elaborate, in order to solve for the induced electromotive force of the harmonic winding, we further analyze the air gap magnetic flux density. It is the total magnetomotive force With air gap permeability The product of , i.e., formula (15).

[0053] (15); In the formula, Indicates the air gap magnetic flux density. Indicates air gap permeability. Indicates the mechanical position of the rotor.

[0054] Furthermore, in this embodiment, the rotor of the self-excited synchronous motor has salient poles, and the air gap permeability is a spatially periodic function with the rotor pole pitch as its period. Therefore, the air gap permeability can be expanded into a Fourier series as follows: (16); In the formula, This represents the DC component of the air gap permeability. For air gap permeability n The amplitude of the second harmonic component. Among them, , Indicates the rotor's mechanical speed. This indicates the initial position of the rotor's mechanical angle.

[0055] Then, by substituting formulas (12) and (16) into formula (15) and using the product-to-sum formula, formula (17) is obtained, where the air gap magnetic flux density contains a variety of spatial and temporal harmonics.

[0056]

[0057] = (17); In formula (17), due to the orthogonality of the cosine function, only the fourth spatial harmonic component contributes to the magnetic flux after integration, which means that the air gap magnetic flux density is required to be... The spatial order satisfies the second spatial harmonic constraint condition. (18), and the integrals of other harmonics in formula (17) are 0. Therefore, the magnetic flux Proportional to the amplitude of the 8th spatial harmonic in the air gap magnetic flux density, i.e. (19), where, This represents a constant related to the parameters of the harmonic winding. ,in,L The length of the iron core. R The radius is ; It represents the amplitude of the 4th spatial harmonic magnetic flux density.

[0058] Next, extract the expression that satisfies the following from the air gap magnetic flux density expression. Substituting the terms of equation (17) into equation (18), we can obtain the magnetic flux expression as follows: (20), In the formula, the summation term is limited to .

[0059] According to Faraday's law of electromagnetic induction, the induced electromotive force of the harmonic winding... for: (twenty one).

[0060] Therefore, the induced electromotive force can be determined. Proportional to the amplitude of the injected high-frequency current angular frequency difference , No. Reciprocal of the subspace harmonic order , No. Winding factor of the subharmonic winding air gap permeability n Amplitude of the second harmonic component Among them, different P In the case of value, and Consistent, however, due to , and The differences in these factors result in inconsistent induced electromotive forces, ultimately leading to different magnitudes of excitation current.

[0061] Steps 1-4: Phase coefficients of harmonic currents Substituting into spatial harmonic constraint condition one and spatial harmonic constraint condition two, the phase coefficients are calculated. corresponding value, Take a non-negative integer, then select The phase coefficient corresponding to the minimum value And control the phase difference between the high-frequency harmonic currents of two adjacent phases to be 2. π / 11 is used to inject high-frequency harmonic current into the stator side of the self-excited synchronous motor.

[0062] To elaborate, under the constraints of spatial harmonic constraint condition one in step 1-2 and spatial harmonic constraint condition two in step 1-3, for P The analysis was performed on different cases ranging from 1 to 10, and the results are shown in Table 1.

[0063]

[0064] Table 1. Coefficients for different phase sequences P Harmonic analysis under certain conditions Table 1 shows that when the amplitude and frequency of high-frequency harmonic currents are the same, different phase coefficients... P Magnetomotive forces generating different spatial harmonic orders, for example, when the phase coefficient... P When =2, it will produce Spatial harmonic magnetomotive forces of orders 2, 9, 13, 20, 24, etc. Then, only those satisfying... and n Only when the phase coefficient is a non-negative integer can the magnetomotive force on the stator side be coupled to the rotor side. Not all spatial harmonic magnetomotive forces generated on the stator side can be effectively coupled to the rotor side. For example, when the phase coefficient is a non-negative integer... P When =2, only The 2nd, 9th, 13th, 20th, 24th, 31st, and 35th spatial harmonic magnetomotive forces can be obtained through... n =The second harmonic magnetic permeability is coupled to the rotor side.

[0065] As can be seen from Table 1 above, when the phase coefficient P = 3, 8 o'clock n The minimum value is achieved by controlling the phase difference between two adjacent high-frequency harmonic currents to be 6π / 11 or 16π / 11, thereby injecting high-frequency harmonic current to increase the excitation current.

[0066] Furthermore, the phase coefficient P and 11- P The situation presents a symmetrical pattern; therefore, the following... P Taking values ​​1 to 5 as examples, we will explain the details for each... P The most important coupling path under the given value, its key parameters and coupling efficiency are summarized in Table 2.

[0067]

[0068] Table 2 Different phase coefficients P Coupling efficiency analysis under the following conditions As shown in Table 2, when the phase coefficient P = 1, 10, lowest harmonic u It is 32, therefore Smaller, it is through magnetic permeability harmonics with smaller amplitude. The coupling to the rotor side results in low excitation efficiency.

[0069] When the phase coefficient P When the spatial harmonic order is 2, 9 or 5, 6, the spatial harmonic order is relatively high, 1 / uThe winding factor is small, the magnetic permeability harmonic amplitude is moderate, and the overall excitation efficiency is relatively high.

[0070] When the phase coefficient P = At times 4 and 7, the spatial harmonic order is relatively high ( u =40, 48), the winding factor is very high, but through harmonic permeability , The coupling amplitude is typically lower than that of low-order harmonic permeability, and the efficiency is rated as moderate.

[0071] When the phase coefficient P = 3, 8, the spatial harmonic order is relatively low ( u =8, 1 / u (Large), winding factor is medium, but it passes through the magnetic permeability harmonics with the largest amplitude ( The coupling results in high overall excitation efficiency.

[0072] This verifies the phase coefficient. P = 3. The overall excitation efficiency is higher when the value is 8.

[0073] Step 2: Input the high-frequency harmonic current mentioned above into the motor control system. After the high-frequency harmonic current is given coordinate rotation transformation in the motor control system, it is used as the current given on each decoupled shaft sequence. It is compared with the actual value of each shaft sequence current obtained after coordinate transformation of the actual collected stator phase current. Then it is input into the PIR regulator to generate the stator voltage given value, which is superimposed with the fundamental voltage given value and acts together in the inverter to output PWM signal to the stator side (i.e. each stator winding) of the self-excited synchronous motor.

[0074] The above description is only a preferred embodiment of this invention. Any equivalent changes and modifications made that fall within the scope of the claims of this invention shall be deemed to fall within the scope of the claims of this invention.

Claims

1. A self-excited magneto, characterized in that: The system includes a motor body and a motor control system. The motor control system includes an inverter composed of eleven-phase IGBT bridge arms. The motor body includes a rotor and a stator mounted on the outside of the rotor. The stator includes a stator core and several stator windings. The first ends of each stator winding are connected together, and the second ends are respectively connected to the signal output terminals of the inverter. A circuit board with an integrated rectifier circuit is mounted on the first end of the rotor. The rotor includes a rotor core and several harmonic windings and excitation windings. The rotor core has eight rotor teeth arranged circumferentially. Each harmonic winding and each excitation winding is wound on the corresponding rotor tooth. The harmonic windings are divided into two groups, namely the first harmonic winding and the second harmonic winding. The winding directions of the first harmonic windings and the second harmonic windings are the same and they are connected in a star configuration. The first ends of the first harmonic windings are connected together to form a star neutral point. The first end of the second harmonic winding is connected one-to-one with the midpoint of each bridge arm in the rectifier circuit. The second ends of the first harmonic windings and the second harmonic windings are connected in series one-to-one. The winding directions of the excitation windings on adjacent rotor teeth are opposite, and the two ends of the excitation windings are electrically connected to the DC output terminals of the rectifier circuit.

2. The self-excited magneto according to claim 1, characterized in that: The motor body is an 11-slot, 8-pole synchronous motor.

3. A self-excited magneto according to claim 2, characterized in that: The rectifier circuit is an 8-phase diode rectifier circuit.

4. A self-excited motor according to claim 2, characterized in that: The stator winding is an 11-phase concentrated stator winding.

5. A self-excited magneto according to claim 2, characterized in that: A filter capacitor is connected between the excitation winding and the rectifier circuit to suppress excitation current pulsation.

6. A motor control strategy based on high-frequency harmonic current phase optimization, characterized in that, The self-excited motor as described in any one of claims 1-5 includes the following steps: Step 1: Generate a preset high-frequency harmonic current. The phase of the high-frequency harmonic current is determined according to the following steps. Step 1-1: Construct a high-frequency harmonic current control model for a multiphase self-excited motor. The high-frequency harmonic current control model is as follows: In the formula, This represents the high-frequency harmonic current of an 11-phase self-excited synchronous motor. Indicates time; This indicates the phase sequence number of the self-excited synchronous motor. =0, 1, ..., 10, respectively corresponding to the th Phase, First Phase, ..., First Mutually; Indicates the amplitude of the fundamental current. Indicates the phase of the fundamental current. Indicates the amplitude of harmonic current. Indicates the phase of the harmonic current; The phase coefficient representing the harmonic current. =1, 2, ..., 10; Step 1-2: Use the first spatial harmonic constraint condition to determine whether spatial harmonics exist in the total magnetomotive force. This first spatial harmonic constraint condition is... In the formula, Indicates the spatial harmonic order. m It can be any integer; Steps 1-3: Use the second spatial harmonic constraint condition to determine whether the spatial harmonic order in the air gap magnetic flux density is satisfied. This second spatial harmonic constraint condition is... , Represents a non-negative integer; Steps 1-4: The phase coefficients of the harmonic currents... Substituting these values ​​into the first and second spatial harmonic constraint conditions, each phase coefficient is calculated. corresponding value, Take a non-negative integer, then select The phase coefficient corresponding to the minimum value And control the phase difference between the high-frequency harmonic currents of two adjacent phases to be 2. π / 11 is used to inject the high-frequency harmonic current; Step 2: Input the high-frequency harmonic current into the motor control system. The motor control system processes the high-frequency harmonic current to generate a stator voltage setpoint, which is then superimposed on the fundamental voltage setpoint and acts together in the inverter to output a PWM signal to the stator winding of the self-excited motor.

7. The motor control strategy based on high-frequency harmonic current phase optimization according to claim 6, characterized in that: In steps 1-2, Fourier decomposition is used to obtain the first... The magnetomotive force of the phase winding is, In the formula, Indicates the number of turns in series per phase. ; For the first The winding factor of the subharmonics, in which the lumped winding ; Indicates the first k The axial position of the phase winding, where ; Indicates the stator inscribed angle; The total magnetomotive force of the 11-phase harmonic winding is The formula for the total magnetomotive force is obtained by calculation. ; Based on the sum-to-product formula for trigonometric functions, the total magnetomotive force formula is transformed into... ； The summation term in the total magnetomotive force formula is denoted as follows: S 1. S 2. The expressions are as follows: ， ， In order to make S 1. S 2 is not zero. P and Must meet: and In the formula, r and s All are integers, thus obtaining the first spatial harmonic constraint condition.

8. The motor control strategy based on high-frequency harmonic current phase optimization according to claim 7, characterized in that: In steps 1-3, the formula for calculating the air gap magnetic flux density is as follows: In the formula, Indicates the air gap magnetic flux density. Indicates air gap permeability. This indicates the rotor's mechanical position; wherein, the air gap magnetic permeability, expanded into a Fourier series, is... In the formula, This represents the DC component of the air gap permeability. For air gap permeability n The amplitude of the second harmonic component; among which... , The rotor's mechanical speed. This is the initial position of the rotor's mechanical angle; Using the product-sum formula, the specific formula for calculating the air gap magnetic flux density is as follows: = ， Due to the orthogonality of the cosine function, the integral requires that the spatial order of the air gap magnetic flux density satisfy the second spatial harmonic constraint condition.

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