阅读说明：本技术 一种九相半匝线圈发电机矢量控制装置及控制方法 (Nine-phase half-turn coil generator vector control device and control method ) 是由 刘金凤 刘蓝田 何佳伟 曲鑫 于 2020-05-22 设计创作，主要内容包括：本发明公开了一种九相半匝线圈发电机矢量控制装置及控制方法,涉及九相半匝线圈发电机矢量控制领域。本发明针解决现有技术中的电机控制基本采用谐波抑制的方式进行控制,不能对谐波加以利用的问题。本发明的子空间分离单元,用以接收九相半匝线圈发电机的相电压,对所述相电压进过坐标变换和曲线拟合后分离出谐波子空间和谐波子空间；扇区判断单元,用以判断参考电压矢量所处的扇区；工作状态时间单元,用以计算个各子空间各工作状态作用时间；开关顺序单元,用以根据所述换向时间得到调制波。本发明将谐波加以利用,输出带有稳定特定次数谐波的电压电流,实现含有齿谐波的模块化整流组件的矢量控制。(The invention discloses a nine-phase half-turn coil generator vector control device and a nine-phase half-turn coil generator vector control method, and relates to the field of nine-phase half-turn coil generator vector control. The invention aims to solve the problem that the motor control in the prior art is basically controlled in a harmonic suppression mode and cannot utilize harmonics. The subspace separation unit is used for receiving phase voltage of a nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage; a sector judgment unit for judging a sector in which the reference voltage vector is located; the working state time unit is used for calculating the action time of each working state of each subspace; and the switching sequence unit is used for obtaining a modulation wave according to the commutation time. The invention utilizes the harmonic wave, outputs the voltage current with stable specific harmonic wave, and realizes the vector control of the modularized rectifying component containing the tooth harmonic wave.)

1. The utility model provides a nine-phase half-turn coil generator vector control device, includes controller, nine-phase rectifier and nine-phase half-turn coil generator, its characterized in that includes:

the subspace separation unit is used for receiving phase voltage of the nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage;

a sector judgment unit for judging the sector where the reference voltage vector of each subspace is located;

the working state time unit is used for calculating the action time of each working state of each subspace;

and the switching sequence unit is used for obtaining a modulation wave according to the commutation time.

2. The nine-phase half-turn coil generator vector control device of claim 1, wherein the subspace separation unit comprises:

the coordinate transformation module is used for transforming the three-phase voltage coordinate into a dq coordinate system;

and the curve fitting module is used for separating harmonic components of the voltage waveform after the voltage waveform is fitted, and projecting the subspaces of the harmonic components to α - β subspaces through clarke transformation respectively so as to obtain a harmonic subspace and a fundamental wave subspace.

3. The nine-phase half-turn coil generator vector control device according to claim 1, wherein the sector judgment unit comprises:

the sector variable reduction module establishes an ABCDEFGHI nine-phase coordinate system, so that an axis A is superposed with an axis β of the two-phase static orthogonal coordinate system, and a fundamental wave subspace generates nine variables Bj, wherein j is 0, 1, … and 8;

the sector judgment module is used for determining the sector where the space vector is located according to the variable Bj;

and the sequence output module is used for reordering the sector output sequence.

4. The nine-phase half-turn coil generator vector control device of claim 1, wherein the operating state time unit comprises:

the intermediate variable module is used for calculating intermediate variables of the action time of each working state;

and the centralized processing module is used for receiving the intermediate variable and obtaining the duration time of each working state after phase shifting.

5. The nine-phase half-turn coil generator vector control device according to claim 1, wherein the switch control unit comprises a time conversion module and a sequential switching module.

6. A nine-phase half-turn coil generator vector control method is characterized by comprising the following steps:

receiving phase voltage of a nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage;

judging the sector where the reference voltage vector of each subspace is located;

calculating the action time of each working state of each subspace;

and obtaining a modulation wave according to the commutation time.

7. The nine-phase half-turn coil generator vector control method of claim 6, wherein separating harmonic subspaces and harmonic subspaces after coordinate transformation and curve fitting the phase voltages comprises:

transforming the three-phase voltage coordinate into a dq coordinate system;

and fitting the voltage waveforms, separating harmonic components, and projecting subspaces of the harmonic components to α - β subspaces through clarke transformation respectively to obtain harmonic subspaces and fundamental wave subspaces.

8. The nine-phase half-turn coil generator vector control method of claim 6, wherein determining the sector in which the reference voltage vector is located comprises:

establishing an ABCDEFGHI nine-phase coordinate system, enabling an axis A to coincide with an axis β of the two-phase static orthogonal coordinate system, and generating nine variables Bj, wherein j is 0, 1, … and 8 in a fundamental wave subspace;

determining a sector where the space vector is located according to the variable Bj;

the sector output order is reordered.

9. The nine-phase half-turn coil generator vector control method of claim 6, wherein calculating the action time of each working state of each subspace comprises:

calculating the intermediate variable of the action time of each working state;

and receiving the intermediate variable, and obtaining the duration of each working state after phase shifting.

Technical Field

The invention relates to the field of vector control of nine-phase half-turn coil generators, in particular to a vector control device and a vector control method of a nine-phase half-turn coil generator.

Background

With the development of power electronic devices, microprocessor technology and control theory, the advantages of low voltage, high power and good fault-tolerant performance of the multi-phase motor make the multi-phase motor especially suitable for the application occasions with limited voltage. Since the more the number of turns of the stator winding, the higher the induced electromotive force, it is difficult to realize high-speed operation of the nine-phase half-turn coil generator at a lower voltage. The nine-phase permanent magnet synchronous nine-phase half-turn coil generator with each phase only having half-turn coils is adopted, so that the phase voltage can be effectively reduced, and low-voltage high-power output is realized. The control mode and harmonic analysis utilization of the nine-phase rectification system are the key points of research in the text.

At present, control technologies generally adopted by a multiphase nine-phase half-turn coil generator rectification mode comprise a carrier-based multiphase PWM technology, a maximum vector SVPWM technology and a space vector multi-dimensional SVPWM technology. The drawbacks of carrier-based PWM are slow dynamic response process and inability to accurately calculate the on-time of the power switch of the rectifier module in each sampling period. SVPWM enables better performance of the power switching devices than carrier-based PWM. Many researchers are currently working on harmonics in multi-phase motor systems. The interference of harmonic waves to the system can be eliminated by selecting different space vectors. The injection of third and fifth harmonics into the motor proves that certain harmonics can provide the motor power density. In addition, a reactor is added into the stator winding to eliminate specific times of harmonic waves of the nine-phase half-turn coil generator so as to achieve the purpose of retaining useful harmonic waves. There have also been attempts by researchers to utilize harmonics in hybrid excitation machines. In summary, current research reports mainly focus on harmonic suppression, and in a power generation system with a rectifier module, rectification is rarely studied for the utilization of ac-side harmonics.

Two vector control methods of permanent magnet synchronous motors are disclosed in Chinese invention patents CN110034713A and CN 110011582A. The method starts from the angle of a motor body, a mathematical model of stator current time derivative is solved by utilizing a mathematical model of the stator voltage of the permanent magnet synchronous motor, and then the rotor contained in a high-frequency stator current difference model is obtainedAnd sub-position, so that the permanent magnet synchronous motor is controlled according to the position of the rotor to realize vector control. And the latter collects three-phase current signals under a static coordinate system through a closed-loop feedback link from the perspective of the system, and obtains a current component i under a d-q coordinate system after conversion processing_q、i_dWill give the motor speed ω^*Obtaining speed deviation after making difference with the motor rotation speed omega, and obtaining a current given value i by taking the speed deviation as the input of a repeated active disturbance rejection controller_q ^*(ii) a Will i_q ^*-i_q、i_d ^*And 0 is used as the input quantity of the q-axis and d-axis current loop PI controllers respectively, so that the motor is smoothly controlled.

The above two ways can realize the control of the motor, but both have obvious defects. When a nine-phase half-turn coil generator containing a large amount of harmonic waves is controlled from the perspective of a motor body, a mathematical model of the generator becomes extremely complex, and the calculation is quite complex. From the system perspective, the conventional voltage loop and current loop cannot accurately sample and analyze a large amount of harmonics. The nine-phase half-turn coil generator based on half-turn coil technology employed herein is distinguished from conventional generators.

Disclosure of Invention

In order to solve the problems, the invention provides a nine-phase half-turn coil generator vector control device and a control method, which utilize harmonic waves, output voltage current with stable specific-order harmonic waves and realize vector control of a modular rectification component containing tooth harmonic waves.

The invention provides a nine-phase half-turn coil generator vector control device on one hand, which comprises a controller, a nine-phase rectifier and a nine-phase half-turn coil generator, and comprises:

the subspace separation unit is used for receiving phase voltage of the nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage;

a sector judgment unit for judging the sector where the reference voltage vector of each subspace is located;

the working state time unit is used for calculating the action time of each working state of each subspace;

and the switching sequence unit is used for obtaining a modulation wave according to the commutation time.

Further, the subspace separation unit includes:

the coordinate transformation module is used for transforming the three-phase voltage coordinate into a dq coordinate system;

and the curve fitting module is used for separating harmonic components of the voltage waveform after the voltage waveform is fitted, and projecting the subspaces of the harmonic components to α - β subspaces through clarke transformation respectively so as to obtain a harmonic subspace and a fundamental wave subspace.

Further, the sector determination unit includes:

the sector variable reduction module establishes an ABCDEFGHI nine-phase coordinate system, so that an axis A is superposed with an axis β of the two-phase static orthogonal coordinate system, and a fundamental wave subspace generates nine variables Bj, wherein j is 0, 1, … and 8;

the sector judgment module is used for determining the sector where the space vector is located according to the variable Bj;

and the sequence output module is used for reordering the sector output sequence.

Further, the operating state time unit includes:

the intermediate variable module is used for calculating intermediate variables of the action time of each working state;

and the centralized processing module is used for receiving the intermediate variable and obtaining the duration time of each working state after phase shifting.

Further, the switch control unit comprises a time conversion module and a sequence switching module.

The invention provides a nine-phase half-turn coil generator vector control method in a second aspect, which comprises the following steps:

receiving phase voltage of a nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage;

judging the sector where the reference voltage vector of each subspace is located;

calculating the action time of each working state of each subspace;

and obtaining a modulation wave according to the commutation time.

Further, the separating the harmonic subspace and the harmonic subspace after the phase voltage is subjected to coordinate transformation and curve fitting comprises:

transforming the three-phase voltage coordinate into a dq coordinate system;

and fitting the voltage waveforms, separating harmonic components, and projecting subspaces of the harmonic components to α - β subspaces through clarke transformation respectively to obtain harmonic subspaces and fundamental wave subspaces.

Further, determining the sector where the reference voltage vector is located includes:

establishing an ABCDEFGHI nine-phase coordinate system, enabling an axis A to coincide with an axis β of the two-phase static orthogonal coordinate system, and generating nine variables Bj, wherein j is 0, 1, … and 8 in a fundamental wave subspace;

determining a sector where the space vector is located according to the variable Bj;

the sector output order is reordered.

Further, calculating the action time of each working state of each subspace, including:

calculating the intermediate variable of the action time of each working state;

and receiving the intermediate variable, and obtaining the duration of each working state after phase shifting.

As described above, the vector control device and the vector control method for nine-phase half-turn coil generator according to the present invention have the following effects:

according to the invention, the high-quality harmonic voltage vector generated by the nine-phase half-turn coil generator and the nine-phase SVPWM method are utilized to independently synthesize and finally combine the fundamental wave and the control signal of the harmonic subspace, so that the defect that the signal containing the harmonic wave cannot be accurately sampled by the traditional closed-loop control is solved.

Drawings

FIG. 1 is a block diagram of the overall structure of a nine-phase half-turn coil generator vector control apparatus according to an embodiment of the present invention;

FIG. 2 is a block diagram of a subspace partitioning unit according to an embodiment of the present invention;

FIG. 3 is a block diagram of a sector determination unit according to an embodiment of the present invention;

FIG. 4 is a block diagram of an operating state time cell according to an embodiment of the present invention;

FIG. 5 is a block diagram of a switch sequence unit according to an embodiment of the present invention;

FIG. 6 is a schematic circuit diagram of a nine-phase rectifier topology according to an embodiment of the present invention;

FIG. 7 is a flow chart of a nine-phase half-turn coil generator vector control method in accordance with an embodiment of the present invention; .

FIG. 8 is a vector distribution diagram of fundamental and harmonics, FIG. 8a is α₁-β₁The voltage vector distribution corresponding to the subspace, α in FIG. 8b₃-β₃Subspace corresponding voltage vector distribution, α in FIG. 8c₅-β₅The voltage vector distribution corresponding to the subspace, α in FIG. 8d₇-β₇Voltage vector distribution corresponding to the subspace;

FIG. 9 is a schematic diagram of sector division according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of a model constructed according to an embodiment of the present invention;

FIG. 11 is a diagram of 18 sector sequential output according to an embodiment of the present invention;

FIG. 12 is a waveform diagram of an intermediate variable in accordance with an embodiment of the present invention;

FIG. 13 is a waveform diagram of a modulated wave signal according to an embodiment of the present invention;

FIG. 14 is a waveform diagram of a load jump simulation output according to an embodiment of the present invention;

FIG. 15 shows simulated results of i according to an embodiment of the present invention₁、i₃、i₅、i₇A track map under a corresponding d-q coordinate system;

FIG. 16 is a graph of output current and voltage waveforms of a simulation system according to an embodiment of the present invention, FIG. 16a is a system output current waveform, and FIG. 16b is a system output voltage waveform;

FIG. 17 is a diagram of a model of a conventional rectifier system in accordance with one embodiment of the present invention;

fig. 18 is a diagram illustrating the FFT and THD analysis results of the nine-phase rectification system according to the embodiment of the present invention;

fig. 19 is a diagram illustrating the results of the FFT transformation and the THD analysis of the three-phase rectification system according to the embodiment of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

As shown in fig. 1, the nine-phase half-turn coil generator vector control apparatus of the present embodiment includes a controller, a nine-phase rectifier, and a nine-phase half-turn coil generator, and includes a subspace separation unit 100, a sector determination unit 200, a working state time unit 300, a switching sequence unit 400, and a natural sampling unit 500, where the subspace separation unit 100 is configured to receive phase voltages of the nine-phase half-turn coil generator, and separate a harmonic subspace and a harmonic subspace after performing coordinate transformation and curve fitting on the phase voltages; the sector judgment unit 200 is used for judging a sector where the reference voltage vector is located; the working state time unit 300 is used for calculating the action time of each working state of each subspace; the switching sequence unit 400 is used for obtaining a modulation wave according to the commutation time.

As shown in fig. 2, the subspace separation unit 100 of this embodiment is configured to separate a subspace for subsequent calculation, and includes a coordinate transformation module 101 and a curve fitting module 102, where the coordinate transformation module 101 is configured to transform the three-phase voltage coordinate into a dq coordinate system, and the curve fitting module 102 is configured to separate a harmonic component of the voltage waveform after fitting the voltage waveform, and project the subspace of the harmonic component to α - β subspaces through clarke transformation, respectively, so as to obtain a harmonic subspace and a fundamental subspace.

First of space vector regulationStep (B) is to determine the sector where the space voltage vector determined by α - β is located, and the sector determination unit 200 of the present embodiment includes a sector variable reduction module 201, a sector determination module 202, and a sequence output module 203, as shown in fig. 3, where the sector variable reduction module is used to establish an ABCDEFGHI nine-phase coordinate system, so that the axis a coincides with the axis of the two-phase stationary orthogonal coordinate system β, and the fundamental wave subspace generates nine variables B_jJ is 0, 1, …, 8; the sector judgment module is used for determining the sector where the space vector is located according to the variable Bj; and the sequence output module is used for reordering and outputting the sector output sequence.

As shown in fig. 4, the working state time unit 300 of this embodiment includes an intermediate variable module 301 and a centralized processing module 302, where the intermediate variable module synthesizes, in each sector, an expected voltage vector in each sector according to two adjacent voltage vectors and a zero vector, and obtains two adjacent voltage vector action times corresponding to the expected voltage vector, where the action times are intermediate variables; and the centralized processing module receives the intermediate variable, obtains the duration of each working state after phase shifting, and has the function of preventing overmodulation.

As shown in fig. 5, the switch control unit 400 of this embodiment includes a time conversion module 401 and a sequential switching module 402, where the time conversion module obtains the switching tube operating time from the duration of the operating state of the time conversion module 401, and the sequential switching module 402 is configured to convert a signal into a modulated wave signal.

As shown in fig. 7, the vector control method for a nine-phase half-turn coil generator in this embodiment includes the following steps:

s1, receiving phase voltage of the nine-phase half-turn coil generator, and separating a harmonic subspace and a harmonic subspace after coordinate transformation and curve fitting are carried out on the phase voltage;

the method specifically comprises the following steps:

s11, converting the three-phase voltage coordinate into a dq coordinate system;

and S12, fitting the voltage waveforms, separating harmonic components, and projecting the subspaces of the harmonic components to α - β subspaces through Clarke transformation respectively to obtain harmonic subspaces and fundamental wave subspaces.

The aging current of the nine-phase permanent magnet synchronous motor in the embodiment mainly comprises fundamental waves, third harmonics, fifth harmonics and seventh harmonics, the higher harmonic content is very low and can be ignored, and the nine-phase rectifier in the embodiment has a power factor of 2⁹The remaining 510 operating states correspond to different nonzero voltage vectors, and the fundamental wave vector and the harmonic vector are projected to α - β subspace to obtain a fundamental wave voltage vector, a third harmonic voltage vector, a fifth harmonic voltage vector and a seventh harmonic voltage vector as follows:

in the formula of U_dcIs the DC bus voltage, gamma-e^j2π/9,e^jx＝cosx+jsinx；

Defining a switching function

Four subspace voltage vector profiles from the fundamental voltage vector, the third harmonic voltage vector, the fifth harmonic voltage vector, and the seventh harmonic voltage vector are shown in FIG. 8, at α₁-β₁，α₅-β₅And α₇-β₇The working states (000000000) and (111111111) in the subspace correspond to the zero vector at α₃-β₃It is impractical to use all of the 512 operating states corresponding to the α - β subspaces for synthesizing the desired output voltage vector, and this embodiment divides the remaining operating states into four groups, 1 and 111111111 respectively, except for (000000000) and (111111111)_on-8_off}，{2_on-7_off}，{3_on-6_offAnd {4 }_on-5_offAnd the numbers in brackets indicate the number of the bridge arms of the upper bridge arm which are switched on or off. According to the principle that adjacent conducting bridge arms synthesize the maximum vector of the amplitude, the maximum vector is respectively from {1_on-8_off}，{2_on-7_off}，{3_on-6_offAnd {4 }_on-5_offSelecting 18 working states with the maximum amplitude values from the four groups of working states {1 }_on-8_off}_max、{2_on-7_off}_max、{3_on-6_off}_maxAnd {4_on-5_off}_maxEach subspace has 72 working states, the 72 working states synthesize a desired output voltage vector by the voltage vectors corresponding to the subspaces, and the 72 vectors are distributed in 18 directions in the space. Each subspace is therefore divided into 18 sectors by the voltage vectors corresponding to the 72 operating states.

S2, judging the reference voltage vector u of each subspace_1ref、u_3ref、u_5ref、u_7refThe sector in which the cell is located;

s21, dividing the voltage vector into 18 sectors in the α - β subspace of the fundamental wave, taking 0-20 degrees as the first sector, numbering according to the anticlockwise sequence, establishing an ABCDEFGHI nine-phase coordinate system, enabling the A axis to coincide with the β axis of the two-phase static orthogonal coordinate system, and generating nine variables B in the fundamental wave subspace_j，j＝0，1，…，8，B_jIs u_α1And u_β1Projection in a nine-phase coordinate system;

s22, determining the sector where the space vector is located according to the variable Bj;

introduce a function sgn (x), and

defining a sector judgment value P:

and obtaining the sector where the reference voltage vector is located according to the P value.

And S23, reordering the sector output sequence.

In the embodiment, one switch element in the simulink is adopted to change the original output sequence to output the output sequence from 1 to 18, so that the subsequent calculation is simplified and the model building difficulty is reduced.

S3, calculating the action time of each working state of each subspace;

s31, the working states include a non-zero working state and a zero working state, in this embodiment, the action time of each of the 8 non-zero working states is t_i(i is 1, 2, …, 8), and the zero-operation-state action time is t₀And t₉Obtaining the intermediate variable t of the action time of each working state according to the volt-second balance principle_xAnd t_ySaid intermediate variable t_xAnd t_yFor the decomposition of the voltage vector into u in each sector_xAnd u_yThe action time of (a) is shown in the following formula;

in the formula, T_sThe switching period of the nine-phase rectifier; u. of_x1、u_x2、u_x3、u_x4、u_y1、u_y2、u_y3、u_y4Respectively for the desired voltage vector u in each subspace_vref(v ═ 1, 3, 5, 7) the projected values at the two boundaries of the sector in which they are located are:

in the formula, theta_ν(v ═ 1, 3, 5, 7) is α_v-β_vExpected voltage vector u in subspace_νrefThe included angle between the first sector and the initial edge of the first sector;

set four constants K_j(j is 1, 2, 3, 4), let K₁＝sin(π/9)，K₂＝sin(2π/9)，K₃＝sin(3π/9)，K₄＝sin(4π/9)。{1_on-8_off}_max、{2_on-7_off}_max、{3_on-6_off}_maxAnd {4_on-5_off}_maxThe magnitude of the voltage vector corresponding to each of the α - β subspaces is shown in Table 1.

TABLE 1 amplitude of voltage vector corresponding to each of α - β subspaces in four groups of working states

Subspace	{1on-8off}max	{2on-7off}max	{3on-6off}max	{4on-5off}max
					α1-β1	UE	UH	UI	UL
α3-β3	UE	UE	UM	UE
					α5-β5	UE	UA	UD	UC
α7-β7	UE	UG	UF	UB

U in watch_A,U_B,…,U_MPhase voltage corresponding to an operating state, wherein:

U_A＝K₁/K₄*U_E；U_B＝K₁/K₂*U_E；U_C＝K₂/K₄*U_E；U_D＝K₃/K₄*U_E；U_F＝K₃/K₂*U_E；U_G＝K₄/K₂*U_E；U_H＝K₂/K₁*U_E；U_I＝K₃/K₁*U_E；U_L＝K₄/K₁*U_E；U_M＝0,U_E＝2/9*U_d。

in this embodiment, the nine-phase half-turn coil generator includes more complex harmonics, which affect the calculation of the switching time, so the conditions of each subspace are calculated separately, as shown in table 2.

TABLE 2 Effect times of the operating states of the subspaces

The sum of the action time of the zero working state is as follows:

the action times of the two zero-work states have no unique solution, so that there is one degree of freedom. It can be seen from table 1 that the zero vector dispersion implementation method is adopted, i.e., the zero vector is divided into 4 parts on average, one part is placed at the beginning and the end of the switching period, and two parts are placed in the middle.

And S32, receiving the intermediate variable, and obtaining the duration of each working state after phase shifting. In this embodiment, the inverse transformation process of sector judgment coordinate transformation is adopted to implement, and the phase shift refers to a phase shift manner of a trigonometric function in mathematics, which is commonly used in the prior art.

S4, obtaining a modulation wave according to the commutation time; when the voltage space vector is in a certain sector, the control of the rectifier switch tube to the voltage is realized by changing the working state duration t corresponding to two edges of the sector_x、t_yTo complete.

The method specifically comprises the following steps:

s41, intermediate variable t_x、t_yThe vector switching point t is obtained by_jon(j＝1,2,......,9)；

The switching sequence of the switching tube is obtained by combining the above formula with the table 2. In order to determine the maximum value of the modulation factor to prevent overmodulation, a modulation constraint is introduced, in particular the operating state and the configuration of the zero vector involved in the switching pattern must not be necessarily negative, so this embodiment, in combination with the above conditions, yields a modulation constraint: t is t₁+t₂+t₃+t₄+t₅+t₆+t₇+t₈≤1；

Obtaining a constraint in combination with the modulation constraint:

the condition is that the voltage space vector falls at α 1-β 1, this process is extended to all 18 sectors on the α 1- β 1 subspace, resulting in an 18-sided regular polygon as shown in fig. 8, the desired space voltage vector u_1refIs confined within the 18-sided polygon, in which case the maximum voltage magnitude corresponds to the radius of the circle inscribed in the limiting polygon.

And S42, obtaining a modulation wave through sequential switching, inputting the modulation wave to a natural sampling unit, and comparing the carrier wave with the modulation wave through natural sampling to generate a final switch tube control signal. The process of obtaining the modulated wave and the process of generating the switching tube control signal by sequential switching can be realized by a program or a method in the prior art, and the process is not repeated in the application because the part is not the key point of the application.

In the embodiment, when fundamental waves and harmonic waves exist simultaneously, the expected space voltage vector u of each subspace_1ref、u_3ref、u_5ref、u_7refThe rotating speeds are different, the rotating speeds are in different sectors at the same time, each wave crest of the actual voltage waveform is formed by superposing three voltages of different phases, therefore, for the special voltage waveform generated by a half-turn coil motor, the switching sequence corresponding to each space is calculated respectively, and the final thyristor switching signal is obtained through a logic circuit.

In order to further verify the present embodiment, the present embodiment is subjected to modeling verification, and the model is as shown in fig. 10, in the present embodiment, a three-phase permanent magnet synchronous nine-phase half-turn coil generator model established in Ansoft Maxwell is first used to obtain an alternating voltage output result, then, an operation result of the alternating voltage output result is led into Simulink to be used as an input end of a rectification system, and nine phases of a motor are respectively represented by nine controlled current sources to be used as a power supply input of the system. Because 3-order harmonic components in the voltage of the half-turn coil generator are less, the sector judgment module outputs three values which respectively represent sector information of fundamental waves, 5-order harmonics and 7-order harmonics;

the simulation result of the model sector judging unit is shown in fig. 11, and 18 sectors can be sequentially and circularly output in corresponding time. Output node of working state action time unitAs shown in FIG. 12, the result is u_vrefActing time t of two adjacent voltage vectors corresponding to each sector_x、t_yThe modulated wave signal output by the switching sequence control unit is as shown in fig. 13.

When the system load suddenly changes, fig. 14 shows the output voltage and current waveforms of the simulation system, fig. 14a shows the output current waveform when the load suddenly increases, and fig. 14b shows the output current waveform when the load suddenly decreases, and the system has rapid response and strong dynamic response when the load suddenly increases or decreases.

FIG. 15 shows a space current vector i obtained by simulation calculation₁、i₃、i₅、i₇The trajectory in the corresponding d-q coordinate system. FIG. 15a shows a space current vector i₁Trace in dq coordinate system, space current vector i in fig. 15b₃Trace in dq coordinate system, space current vector i in fig. 15c₅Trace in dq coordinate system, space current vector i in fig. 15d₇On the track under the dq coordinate system, the amplitudes of the four groups of space current vectors are changed from large to small, and the four groups of space current vectors move at a constant speed along a circular track.

FIG. 16 shows the final rectified current and voltage waveforms of the simulation system, and the analysis of the diagram shows that the system can be stabilized after 0.001 second, and the stabilized value is 1000A/5V. The direct current pulse frequency is as high as 4000Hz, the system stability is greatly improved compared with the traditional direct current, and the requirement on a filter capacitor is reduced.

To further illustrate the effect of the present embodiment, a conventional rectification system is constructed as shown in fig. 17. The neutral points of the generator are separated to form an asymmetric structure, nine-phase electricity output by the generator can be divided into three groups of conventional three-phase electricity, the three groups of conventional three-phase electricity are respectively rectified, and finally three direct currents are connected in parallel to achieve the final target.

The three-three phase rectification controls the original nine phases separately, vector selection is not flexible enough, and the separation of the voltage space is too complex, and the calculation amount is far larger than that of the nine-phase vector control algorithm. Meanwhile, each period of the three-phase rectification control strategy is subjected to 6 times of commutation, each period of the nine-phase rectification control strategy is subjected to 18 times of commutation, the switching frequency of the special generator system is as high as 54 times, and the switching frequency of the three-phase rectification control strategy is lower, so that the direct-current side is low in pulse frequency, large in pulse amplitude and high in output distortion rate. Fig. 18 and 19 are graphs of the results of the FFT transformation and the THD analysis of the three-phase rectification system and the nine-phase rectification system.

In conclusion, the SVPWM rectification control method for the nine-phase half-turn coil generator coordinates and optimizes the comprehensive application of 72 vectors and 18 sectors by the flexible application of fundamental waves and harmonic subspaces, realizes the control of the power supply voltage containing harmonic waves, greatly improves the system response speed and the direct-current side pulse frequency, and reduces the requirement on a filter capacitor.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.