CN113517845A - Control method for suppressing fifth harmonic current of six-phase motor and system using same - Google Patents

Abstract

The invention provides a control method for suppressing the fifth harmonic current of a six-phase motor and a system using the same. The method includes: calculating and obtaining a reference voltage vector amplitude and a space angle; dividing the space into twelve sectors, and judging the reference voltage The sector where the voltage vector is located; select two voltage vectors on the same axis of the edge of the sector in the fundamental wave space, and calculate the two voltage vectors in the fifth harmonic space based on the principle that the composite volt-second value is zero. The action time in the same cycle, the two voltage vectors are synthesized into an intermediate vector; the action time of the first, second, third and fourth voltage vectors is calculated; based on the principle of minimum switching loss, the action sequence of the voltage vectors is carried out. Distribution; generate the PWM control signal of the six-phase inverter system, and realize the current control of the six-phase inverter system according to the PWM control signal. The technical solution of the present invention is applied to solve the technical problem of the existence of high-order harmonics in the six-phase inverter system in the prior art.

Description

Control method for suppressing fifth harmonic current of six-phase motor and system using the same

technical field

The invention relates to the technical field of harmonic suppression control, in particular to a control method for suppressing fifth harmonic current of a six-phase motor and a system using the same.

Background technique

With the rapid development of power electronics technology, the three-phase AC speed regulation system is becoming more and more mature, but in the field of high-power AC speed regulation, the three-phase AC motor is inevitably affected by dynamic and static voltage equalization due to the need to use power device group technology. Due to the increase in the number of phases, the power of the whole machine can be greatly improved when the voltage and current of each phase are kept within a certain range. Moreover, the multi-phase system has a high fault tolerance rate. When one or several phases fail, the load can still be reduced. As a multi-phase motor, six-phase motors are widely used in high-power and high-reliability applications due to their structural characteristics and high fault tolerance. Therefore, it has become a research hotspot to suppress the high-order harmonics of the six-phase system through a certain control algorithm.

SUMMARY OF THE INVENTION

The invention provides a control method for suppressing the fifth harmonic current of a six-phase motor and a system using the same, which can solve the technical problem of the existence of higher harmonics in the six-phase inverter system in the prior art.

According to an aspect of the present invention, a control method for suppressing the fifth harmonic current of a six-phase motor is provided, and the control method for suppressing the fifth harmonic current for a six-phase motor includes: calculating and obtaining a reference voltage vector according to a stator reference two-phase voltage Amplitude and space angle; according to the maximum amplitude voltage vector output by the six-phase inverter system, the fundamental wave space and the fifth harmonic space are divided into twelve sectors, and the reference voltage vector is determined according to the space angle of the reference voltage vector. Sector; two voltage vectors on the same axis of the edge of the sector are selected in the fundamental wave space, and the effect of the two voltage vectors in the same period is calculated according to the principle that the composite volt-second value in the fifth harmonic space is zero. Time, according to the action time of the two voltage vectors, the two voltage vectors are synthesized into an intermediate vector in the fundamental wave space; according to the first intermediate vector of the first edge of the sector where the reference voltage vector is located, and the second edge of the second edge The intermediate vector synthesizes the reference voltage vector based on the equivalent principle of volt-second value, and calculates and obtains the action time of the first intermediate vector and the action time of the second intermediate vector according to the reference voltage vector, the reference voltage vector amplitude and the space angle. Calculate the action time of the first intermediate vector and the action time of the second intermediate vector to obtain the action time of the first voltage vector, the action time of the second voltage vector, and the action time of the third voltage vector and the The action time of the four voltage vectors; based on the principle of minimum switching loss, the action sequence of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector is allocated to ensure that any switching device of the six-phase inverter system is There is only one on-off in one cycle; according to the action time and action sequence of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector, the modulating wave is generated, and the sawtooth wave is used as the carrier wave. The carriers are compared to generate a PWM control signal of the six-phase inverter system, and the current control of the six-phase inverter system is realized according to the PWM control signal.

的幅值

及空间角度θ可根据

来获取，其中，U_α为参考电压矢量在α方向的分量，U_β为参考电压矢量在β方向的分量。Further, the reference voltage vector

The magnitude of

and the spatial angle θ can be determined according to

to obtain, where U _α is the component of the reference voltage vector in the α direction, and U _β is the component of the reference voltage vector in the β direction.

Further, the method for obtaining the maximum amplitude voltage vector output by the six-phase inverter system specifically includes: calculating and obtaining the fundamental wave space voltage vector and the fifth harmonic space voltage vector of the six-phase inverter system, according to the fundamental wave space voltage vector and The fifth harmonic space voltage vector is calculated to obtain the maximum amplitude voltage vector.

计算获取，其中，

为基波空间电压矢量；

为5次谐波空间电压矢量；U_dc为直流母线电压，

U_dc为直流母线电压。Further, the fundamental wave space voltage vector and the fifth harmonic space voltage vector can be determined according to

Calculated to obtain, where,

is the fundamental space voltage vector;

is the 5th harmonic space voltage vector; U _dc is the DC bus voltage,

U _dc is the DC bus voltage.

获取，其中，V_max为大矢量幅值；V_midl为次大矢量幅值；V_mids为次小矢量幅值；V_min为小矢量幅值。进一步地，根据参考电压矢量所处扇区的第一边缘的第一中间矢量和第二边缘的第二中间矢量以伏秒值等效原理所合成的参考电压矢量为

其中，T₁'为第一中间矢量的作用时间，T₂'为第二中间矢量的作用时间，

为第二中间矢量，T_s为采样周期时间，

为零矢量，T₀'为零矢量作用时间。Further, the amplitude maximum voltage vector V _max can be determined according to

obtain, where V _max is the large vector magnitude; V _midl is the next largest vector magnitude; V _mids is the next small vector magnitude; and V _min is the small vector magnitude. Further, according to the first middle vector of the first edge of the sector where the reference voltage vector is located and the second middle vector of the second edge, the reference voltage vector synthesized by the volt-second equivalent principle is:

Among them, T ₁ ' is the action time of the first intermediate vector, T ₂ ' is the action time of the second intermediate vector,

is the second intermediate vector, T _s is the sampling cycle time,

Zero vector, T ₀ ' is zero vector action time.

其中，

为中间矢量。Further, the action time of the first intermediate vector and the action time of the second intermediate vector are

in,

is the intermediate vector.

其中，T₁为第一电压矢量的作用时间，T₂为第二电压矢量的作用时间，T₃为第三电压矢量的作用时间，T₄为第四电压矢量的作用时间。Further, the action time of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector is

Among them, T1 is the action time of the _first voltage vector, T2 is the action time of the _second voltage vector, T3 is the action time of the _third voltage vector, and T4 is the action time of the _fourth voltage vector.

According to yet another aspect of the present invention, a six-phase inverter system is provided, and the six-phase inverter system performs current control using the above-mentioned control method for suppressing the fifth harmonic current of a six-phase motor.

Further, the six-phase inverter system includes six inverter units connected in parallel, and any inverter unit includes two power switching devices IGBT.

By applying the technical scheme of the present invention, a control method for suppressing the fifth harmonic current of a six-phase motor is provided. The control method selects the fundamental wave plane maximum vector and the second largest vector to synthesize an intermediate vector. The plane is the smallest vector and the second largest vector and is located on the same axis, and the directions are opposite. When synthesizing, it is not necessary to match the vector angle and amplitude. As long as the action time is inversely proportional to the amplitude, the two sets of vectors can be eliminated five times. The influence of the harmonic plane, this method makes the fifth harmonic suppression effect more significant, and the calculation is simpler and easier to implement.

Description of drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention, constitute a part of the specification, are used to illustrate the embodiments of the invention, and together with the description, serve to explain the principles of the invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 shows a schematic structural diagram of a stator of a six-phase motor provided according to a specific embodiment of the present invention.

FIG. 2 shows a schematic structural diagram of a six-phase inverter system provided according to a specific embodiment of the present invention.

FIG. 3 shows a fundamental wave space voltage vector distribution diagram provided according to a specific embodiment of the present invention.

FIG. 4 shows a fifth harmonic space voltage vector distribution diagram provided according to a specific embodiment of the present invention.

FIG. 5 shows a sector distribution diagram provided according to a specific embodiment of the present invention.

FIG. 6 shows a distribution diagram of the coaxial line voltage vector at the start edge of the first sector in the fundamental wave space provided according to a specific embodiment of the present invention.

FIG. 7 shows a distribution diagram of the coaxial line voltage vector at the start edge of the first sector in the fifth harmonic space provided according to a specific embodiment of the present invention.

FIG. 8 shows a schematic diagram of spatial distribution of a composite intermediate vector of two coaxial line vectors according to a specific embodiment of the present invention.

FIG. 9 shows a schematic diagram of an intermediate vector synthesis reference voltage vector provided according to a specific embodiment of the present invention.

FIG. 10 shows a schematic diagram of a first sector voltage vector action sequence and a PWM signal generation principle according to a specific embodiment of the present invention.

FIG. 11 shows a flow chart of the implementation of the SVPWM algorithm provided according to a specific embodiment of the present invention.

FIG. 12 shows a schematic diagram of the output of a sector determination module provided according to a specific embodiment of the present invention.

FIG. 13 shows a schematic diagram of the included angle between the reference voltage vector and the start edge of the sector provided according to a specific embodiment of the present invention.

FIG. 14 shows a schematic diagram of a modulated wave waveform provided according to a specific embodiment of the present invention.

FIG. 15 shows a phase current waveform diagram provided according to a specific embodiment of the present invention.

FIG. 16 shows a phase voltage waveform diagram provided according to a specific embodiment of the present invention.

FIG. 17 shows a speed simulation result diagram provided according to a specific embodiment of the present invention.

FIG. 18 shows a torque simulation result graph provided according to a specific embodiment of the present invention.

FIG. 19 shows a bar graph of the FFT analysis result of the A1 phase current when THD=1.57% provided according to a specific embodiment of the present invention.

Fig. 20(a) shows a motor torque waveform diagram provided according to a specific embodiment of the present invention.

Fig. 20(b) shows a motor torque parameter setting diagram provided according to a specific embodiment of the present invention.

FIG. 20( c ) shows a bar graph of the FFT analysis result of the A1 phase current when THD=1.43% provided according to a specific embodiment of the present invention.

FIG. 20( d ) shows the setting diagram of A1 phase current FFT analysis parameters provided according to a specific embodiment of the present invention when THD=1.43%.

Detailed ways

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise. Meanwhile, it should be understood that, for the convenience of description, the dimensions of various parts shown in the accompanying drawings are not drawn in an actual proportional relationship. Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized description. In all examples shown and discussed herein, any specific value should be construed as illustrative only and not as limiting. Accordingly, other examples of exemplary embodiments may have different values. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

As shown in FIG. 1 to FIG. 20(d), according to a specific embodiment of the present invention, a control method for suppressing the fifth harmonic current of a six-phase motor is provided, and the control method for suppressing the fifth harmonic current of the six-phase motor includes: : Calculate and obtain the reference voltage vector amplitude and space angle according to the stator reference two-phase voltage; divide the fundamental wave space and the fifth harmonic space into twelve sectors according to the maximum amplitude voltage vector output by the six-phase inverter system. The space angle of the voltage vector determines the sector where the reference voltage vector is located; two voltage vectors on the same axis of the edge of the sector are selected in the fundamental wave space, according to the principle that the composite volt-second value in the fifth harmonic space is zero Calculate the action time of the two voltage vectors in the same period, and synthesize the two voltage vectors into an intermediate vector in the fundamental wave space according to the action time of the two voltage vectors; according to the first edge of the sector where the reference voltage vector is located The first intermediate vector of the second edge and the second intermediate vector of the second edge synthesize the reference voltage vector according to the equivalent principle of volt-second value. The action time of the second intermediate vector is calculated according to the action time of the first intermediate vector and the action time of the second intermediate vector to obtain the action time of the first voltage vector, the action time of the second voltage vector and the combined second The action time of the third voltage vector and the action time of the fourth voltage vector of the middle vector; based on the principle of minimum switching loss, the action order of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector is allocated. In order to ensure that any switching device of the six-phase inverter system has only one on-off in one cycle; the modulation is generated according to the action time and action order of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector Using the sawtooth wave as the carrier wave, the modulated wave is compared with the carrier wave to generate the PWM control signal of the six-phase inverter system, and the current control of the six-phase inverter system is realized according to the PWM control signal.

Applying this configuration method, a control method for suppressing the fifth harmonic current of a six-phase motor is provided. The control method selects the maximum vector of the fundamental wave plane and the second largest vector to synthesize the intermediate vector, and these two sets of vectors are in the fifth harmonic plane. The smallest vector and the second largest vector are located on the same axis and in opposite directions. When synthesizing, it is not necessary to match the vector angle and amplitude. Only the action time is inversely proportional to the amplitude to eliminate the fifth harmonic of these two sets of vectors. The influence of the wave plane, this method makes the fifth harmonic suppression effect more significant, and the calculation is simpler and easier to implement.

Specifically, in the present invention, as shown in FIG. 1 , the six-phase motor includes two sets of three-phase windings, wherein A _1s , B _1s , and C _1s are the first set of three-phase windings, and A _2s , B _2s , and C _2s are the first set of three-phase windings. The first set of three-phase windings; the neutral points of the two sets of windings are not connected. Figure 2 is a schematic structural diagram of a six-phase inverter system, wherein VD ₁ , VD ₂ , VD ₃ , VD ₄ , VD ₅ , VD ₆ , VD ₇ , VD ₈ , VD ₉ , VD ₁₀ , VD ₁₁ , VD ₁₂ are power Switching device IGBT, VD ₁ and VD ₂ , VD ₃ and VD ₄ , VD ₅ and VD ₆ , VD ₇ and VD ₈ , VD ₉ and VD ₁₀ , VD ₁₁ and VD ₁₂ form six bridge arms, and the lead points A _1s , B _1s , C _1s , A _2s , B _2s , and C _2s are respectively connected to two sets of three-phase windings correspondingly. 12 IGBTs are connected in parallel to form six inverter units, each inverter unit is independent of each other, and the upper and lower bridge arms of each unit cannot be turned on and off at the same time. The control signals of the six inverter units are S _A ~ S _F , each bridge The turn-on and turn-off of the arm is determined by the following equation:

的幅值

及空间角度θ可根据

来获取，其中，U_α为参考电压矢量在α方向的分量，U_β为参考电压矢量在β方向的分量。具体地，空间矢量脉宽调制(SVPWM)技术由于开关损耗小，直流母线电压利用率高且可以根据逆变器输出电压矢量精确合成参考矢量等优点，被广泛用于电机控制系统中。作为本发明的一个具体实施例，可根据SVPWM模块输入的定子参考两相电压经过计算得出参考电压矢量幅值及空间角度。In order to realize the control of the six-phase motor to suppress the fifth harmonic current, firstly, the reference voltage vector amplitude and space angle are obtained according to the stator reference two-phase voltage calculation. In the present invention, the reference voltage vector

The magnitude of

and the spatial angle θ can be determined according to

to obtain, where U _α is the component of the reference voltage vector in the α direction, and U _β is the component of the reference voltage vector in the β direction. Specifically, space vector pulse width modulation (SVPWM) technology is widely used in motor control systems due to its advantages of low switching loss, high utilization of DC bus voltage, and the ability to accurately synthesize reference vector according to the inverter output voltage vector. As a specific embodiment of the present invention, the reference voltage vector amplitude and the spatial angle can be obtained by calculation according to the stator reference two-phase voltage input by the SVPWM module.

After obtaining the reference voltage vector amplitude and space angle, the fundamental wave space and the fifth harmonic space can be divided into twelve sectors according to the maximum amplitude voltage vector output by the six-phase inverter system. The space angle determines the sector where the reference voltage vector is located. In the present invention, the method for obtaining the maximum amplitude voltage vector output by the six-phase inverter system specifically includes: calculating and obtaining the fundamental wave space voltage vector and the fifth harmonic space voltage vector of the six-phase inverter system, and according to the fundamental wave space voltage The vector and the fifth harmonic space voltage vector are calculated to obtain the maximum amplitude voltage vector.

Specifically, the inverter outputs ²⁶ voltage vectors, and the calculation of the fundamental wave (α-β) space and the 5th harmonic (z1-z2) space space voltage vector is expressed as the following formula:

为基波空间电压矢量；

为5次谐波空间电压矢量；U_dc为直流母线电压，

U_dc为直流母线电压。in,

is the fundamental space voltage vector;

is the 5th harmonic space voltage vector; U _dc is the DC bus voltage,

U _dc is the DC bus voltage.

It can be concluded that the distribution of 64 space voltage vectors in the fundamental wave space output by the six-phase inverter is shown in Figure 3, and the distribution of 64 space voltage vectors in the fifth harmonic space is shown in Figure 4.

According to formula (2), the magnitude of each voltage vector can be obtained:

Among them, V _max is the magnitude of the large vector; V _midl is the magnitude of the next largest vector; V _mids is the magnitude of the next small vector; and V _min is the magnitude of the small vector. Taking the large vector distribution as the standard, the fundamental wave space and the fifth harmonic space are divided into 12 sectors, as shown in Figure 5.

所在边缘围成的扇区。As a specific embodiment of the present invention, the sector where the reference voltage vector is located is determined according to the spatial angle of the reference vector. In this embodiment, the sector where the reference voltage vector is located is the first sector, that is,

The sector bounded by the edge.

After obtaining the sector where the reference voltage vector is located, the intermediate vector can be synthesized. In the fundamental wave space, two voltage vectors on the same axis of the edge of the sector are selected, and the action time of the two voltage vectors in the same period is calculated according to the principle that the composite volt-second value in the fifth harmonic space is zero. The action time of the two voltage vectors synthesizes the two voltage vectors into an intermediate vector in the fundamental wave space.

为例，如图6所示。在五次谐波空间中，

和

为五次谐波空间的小矢量和次大矢量，且方向相反，如图7所示。使该两矢量按五次谐波空间伏秒值之和为零，只需作用时间为其幅值的反比即可，则理论上可以将五次谐波空间空间中小矢量和次大矢量产生的谐波消除。具体计算过程如下：The intermediate vector synthesis part of the SVPWM control algorithm is shown in Figure 6 and Figure 7. In the 12 sectors, the largest vector and the next largest vector at the edge of the sector are selected in the fundamental wave space to synthesize the intermediate voltage vector to

For example, as shown in Figure 6. In the fifth harmonic space,

and

are the small vector and the second largest vector in the fifth harmonic space, and the directions are opposite, as shown in Figure 7. The sum of the two vectors is zero according to the volt-second value of the fifth harmonic space, as long as the action time is inversely proportional to its amplitude, then theoretically, the small vector and the second largest vector in the fifth harmonic space can be generated. Harmonic cancellation. The specific calculation process is as follows:

和

伏秒值之和为0，则：make the fifth harmonic in space

and

The sum of the volt-second values is 0, then:

的作用时间，T₅₇为电压矢量

的作用时间，T₁'为第一中间矢量的作用时间。T ₄₈ is the voltage vector

The action time, _T57 is the voltage vector

The action time of , T ₁ ' is the action time of the first intermediate vector.

The magnitudes of the two vectors in the fundamental wave space are

The magnitudes of the two vectors in the fifth harmonic space are

和

为矢量，具有幅值和方向，幅值为公式6中描述，方向相反。根据公式4和公式6可得

and

is a vector with magnitude and direction, the magnitude is described in Equation 6, and the direction is opposite. According to Equation 4 and Equation 6, we can get

为

Then according to formula 7, the intermediate vector synthesized in the fundamental wave space can be obtained

for

为五次谐波空间中的小矢量，

为五次谐波空间中的次大矢量。in,

is a small vector in the fifth harmonic space,

is the second largest vector in the fifth harmonic space.

如图8所示。The calculation method is the same as that of the above-mentioned embodiment, and 12 intermediate vectors can be synthesized according to the above principles

As shown in Figure 8.

Further, after the intermediate vector of each sector is obtained, the first intermediate vector of the first edge of the sector where the reference voltage vector is located and the second intermediate vector of the second edge can be synthesized by the equivalent principle of volt-second value. Reference voltage vector, according to the reference voltage vector, the reference voltage vector amplitude and the space angle to calculate and obtain the action time of the first intermediate vector and the action time of the second intermediate vector, according to the action time of the first intermediate vector and the action time of the second intermediate vector The time calculation obtains the action time of the first voltage vector, the action time of the second voltage vector, the action time of the third voltage vector and the action time of the fourth voltage vector that are composed of the second intermediate vector.

Specifically, in the present invention, the reference voltage vector magnitude and angle are determined by U _α and U _β :

With reference to FIG. 9 , the reference voltage vector is synthesized according to the first middle vector of the first edge of the sector where the reference voltage vector is located and the second middle vector of the second edge according to the equivalent principle of volt-second value:

为第二中间矢量，T_s为采样周期时间，

为零矢量，T₀'为零矢量作用时间。Among them, T ₁ ' is the action time of the first intermediate vector, T ₂ ' is the action time of the second intermediate vector,

is the second intermediate vector, T _s is the sampling cycle time,

Zero vector, T ₀ ' is zero vector action time.

According to Equation 10 and Equation 9, it can be solved:

为中间矢量，第一中间矢量

是由

合成的，第二中间矢量

是由

合成的，以

作用时间分别为T₁、T₂、T₃、T₄扩展到其他11个扇区，根据公式4、7、8、11可以得到每个扇区矢量作用时间为：

where, in the first sector,

is the intermediate vector, the first intermediate vector

By

composite, second intermediate vector

By

synthetic, with

The action time is T ₁ , T ₂ , T ₃ , and T ₄ respectively. Extend to other 11 sectors. According to formulas 4, 7, 8, and 11, the action time of each sector vector can be obtained as:

的作用时间，T₂为第二电压矢量

的作用时间，T₃为第三电压矢量

的作用时间，T₄为第四电压矢量

的作用时间。Among them, T1 is the _first voltage vector

The action time, T2 is the _second voltage vector

The action time, T3 is the _third voltage vector

The action time, T4 is the _fourth voltage vector

action time.

Twelve sector action time assignments are given in Table 1.

Table 1 Twelve sector vector action time allocation

Further, after the action time of each sector vector is obtained, the action order of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector can be allocated based on the principle of minimum switching loss to ensure six Any switching device of the phase inverter system only has one on-off in one cycle. Then, a modulated wave is generated according to the action time and action order of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector, and the sawtooth wave is used as the carrier wave, and the modulated wave is compared with the carrier wave to generate a six-phase inverse The PWM control signal of the inverter system is used to control the current of the six-phase inverter system according to the PWM control signal.

As a specific embodiment of the present invention, in order to reduce the switching loss, it is necessary to ensure that the power device is switched only once in each cycle, and the sequence of action of the voltage vector needs to be reasonably arranged to generate a PWM wave. Taking the first sector as an example, it is obtained that The voltage vector action sequence is shown in Figure 10. T _on1 , T _on2 , T _on3 , T _on4 , T _on5 , T _on6 , T _on7 , T _on8 , T _on9 , T _on10 , T _on11 , T _on12 are switching times, and the switching times are T _on7 -T _on1 , T _on8 - T _on2 , T _on9 -T _on3 , T _on10 -T _on4 , T _on11 -T _on5 , and T _on12 -T _on6 respectively form modulated waves, which are compared with the sawtooth carrier signal to obtain PWM1-PWM6 switching signals. The current control of the six-direction inverter system is realized according to the PWM1-PWM6 switching signals.

The order of action of other sectors is similar to that of the first sector vector, and the action order of twelve sector vectors is as follows:

Table 2 Sequence of action of twelve sector vectors

According to another aspect of the present invention, a six-phase inverter system is provided, the six-phase inverter system uses the above-mentioned control method for suppressing the fifth harmonic current of a six-phase motor for current control, and the six-phase inverter system It includes six inverter units connected in parallel, and any inverter unit includes two power switching devices IGBT. Because the control method of the present invention selects the maximum vector of the fundamental wave plane and the second largest vector to synthesize the intermediate vector, these two sets of vectors are the smallest vector and the second largest vector in the fifth harmonic plane and are located on the same axis, in opposite directions, and do not need to be synthesized when synthesizing. To match the vector angle and amplitude, as long as the action time is inversely proportional to the amplitude, the influence of these two groups of vectors on the fifth harmonic plane can be eliminated. This method makes the fifth harmonic suppression effect more significant, and the calculation is more efficient. Simple and easy to implement. Therefore, using the current control method in a six-phase inverter system can greatly improve the working performance of the six-phase inverter system.

In order to have a further understanding of the present invention, the following describes the control method for suppressing the fifth harmonic current of a six-phase motor provided by the present invention in detail with reference to FIG. 1 to FIG. 20(d).

As shown in FIG. 1 to FIG. 20(d), according to a specific embodiment of the present invention, a control method for suppressing the fifth harmonic current of a six-phase motor is provided, which can realize a good fifth harmonic current of a six-phase motor control system Inhibitory effect. The current control method includes vector action time calculation, sector partition judgment, intermediate vector synthesis, reference voltage vector synthesis and modulation wave generation. According to the distribution of the space voltage vector output by the six-phase inverter system (that is, the six-phase inverter) in the fundamental wave space and the fifth harmonic space, the largest vector in the fundamental wave space is selected to divide the space into sectors, and combined with the fundamental wave space The largest vector and the second largest vector of the coaxial line in the wave space are processed to synthesize the volt-second value of zero in the fifth harmonic space, and then twelve are synthesized in the fundamental wave space according to the synthesis law in the fifth harmonic space. The intermediate vector is based on the sector where the reference voltage vector is located, and the reference voltage vector is synthesized according to the intermediate vector of the sector where the reference voltage vector is located, and a PWM modulation wave is generated.

Six-phase SVPWM control algorithm with fifth harmonic current suppression mainly includes reference voltage vector calculation module, sector judgment module, intermediate vector synthesis module, vector action time calculation module, vector action sequence distribution module and PWM generation module.

The reference voltage vector calculation module in the SVPWM module calculates the reference voltage vector amplitude and space angle according to the stator reference two-phase voltage input by the SVPWM module.

The sector judgment module in the SVPWM module divides the space into twelve sectors according to the maximum voltage vector output by the six-phase inverter system, and judges the sector in which it is located by combining the SVPWM module input stator with reference to the spatial angle of the two-phase static voltage.

The intermediate vector synthesis module in the SVPWM module selects two voltage vectors on the same axis of the sector edge in the fundamental wave space, and calculates the effect of the two vectors in the same period according to the principle that the synthetic volt-second value in the fifth harmonic space is zero. time, and synthesize the two vectors into an intermediate vector in the fundamental wave space according to the action time of the two vectors.

The vector action time calculation module in the SVPWM module is based on the amplitude and angle of the reference voltage vector, and uses the two intermediate vectors at the edge of the sector where the reference voltage vector is located to synthesize the reference voltage vector with the equivalent principle of volt-second value. The action time of the two intermediate vectors in one cycle, and further calculate the action time of the two sets of coaxial vectors synthesizing the two intermediate vectors.

The vector action order allocation module in the SVPWM module is based on the principle of minimum switching loss, and according to the action order of the two groups of coaxial vectors synthesizing the intermediate vector, a switch can only be turned on and off once in a cycle.

The PWM generation module in the SVPWM module takes the sawtooth wave as the carrier wave, and the on-off time of the switch as the modulation wave, and outputs the PWM control signal of the six-phase inverter after comparison.

以及角度θ，由参考矢量角度θ可以进行参考矢量所处扇区判断，结合扇区信息，参考矢量幅值以及中间矢量合成幅值，进行各矢量作用时间计算，随后根据开关损耗最小原则，进行矢量作用次序分配，得到开关时间T_on1～T_on12，进行PWM信号生成，PWM信号即为逆变器控制信号。The flowchart of the SVPWM current control method provided by the present invention is shown in FIG. 11 . By giving the α and β components of the reference voltage vector, the parametric voltage vector is first synthesized to obtain the reference voltage vector amplitude

And the angle θ, the sector where the reference vector is located can be judged from the reference vector angle θ, combined with the sector information, the reference vector amplitude and the intermediate vector composite amplitude, calculate the action time of each vector, and then according to the principle of minimum switching loss, carry out The vector action sequence is allocated, and the switching times T _on1 to T _on12 are obtained, and the PWM signal is generated, and the PWM signal is the inverter control signal.

The effect of the open-loop detection SVPWM module is shown in Figure 12, Figure 13, and Figure 14. Given the components U _α and U _β of the reference voltage vector in the α and β directions, the SVPWM module is tested, and Figure 12 is the sector judgment module. The output is a continuously changing staircase waveform. Figure 13 is a waveform diagram of the included angle between the reference voltage vector and the start edge of the sector. Since the included angle θ only changes from 0° to 30°, the change waveform of the included angle θ is a sawtooth wave with the highest point For arctan30°. Figure 14 shows the modulated waveform, which is a three-headed saddle wave.

Figures 15 to 19 show the simulation results of the SVPWM six-phase motor control system with the fifth harmonic current suppression effect. The motor starts and runs at no-load. Figure 15 shows the stator phase current waveform. Due to the harmonic suppression effect, The phase current has a relatively high sine degree. Figure 16 shows the voltage waveform of the motor A1 phase stator terminal, Figure 17 shows the motor speed waveform, Figure 18 shows the motor torque waveform, and Figure 19 shows the FFT analysis result of the motor phase current. The SVPWM method of fifth harmonic suppression has a low total harmonic distortion rate, and the fifth harmonic suppression effect is remarkable.

In summary, the present invention provides a control method for suppressing the fifth harmonic current of a six-phase motor. The method selects the maximum vector of the fundamental wave plane and the second largest vector to synthesize an intermediate vector, and these two sets of vectors are in the fifth harmonic plane. The smallest vector and the second largest vector are located on the same axis and in opposite directions. When synthesizing, it is not necessary to match the vector angle and amplitude. Only the action time is inversely proportional to the amplitude to eliminate the fifth harmonic of these two sets of vectors. The influence of the wave plane, this method makes the fifth harmonic suppression effect more significant, and the calculation is simpler and easier to implement.

For ease of description, spatially relative terms, such as "on", "over", "on the surface", "above", etc., may be used herein to describe what is shown in the figures. The spatial positional relationship of one device or feature shown to other devices or features. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or features would then be oriented "below" or "over" the other devices or features under other devices or constructions". Thus, the exemplary term "above" can encompass both an orientation of "above" and "below." The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing corresponding components. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood to limit the scope of protection of the present invention.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A control method for suppressing the fifth harmonic current of a six-phase motor, wherein the control method for suppressing the fifth harmonic current of the six-phase motor comprises: Calculate the reference voltage vector amplitude and space angle according to the stator reference two-phase voltage; According to the maximum amplitude voltage vector output by the six-phase inverter system, the fundamental wave space and the fifth harmonic space are divided into twelve sectors, and the sector where the reference voltage vector is located is determined according to the spatial angle of the reference voltage vector; In the fundamental wave space, two voltage vectors on the same axis of the edge of the sector are selected, and the action time of the two voltage vectors in the same cycle is calculated according to the principle that the composite volt-second value in the fifth harmonic space is zero. , synthesizing the two voltage vectors into an intermediate vector in the fundamental wave space according to the action time of the two voltage vectors; According to the first middle vector of the first edge of the sector where the reference voltage vector is located, and the second middle vector of the second edge, the reference voltage vector is synthesized according to the volt-second equivalent principle. According to the reference voltage vector, all The reference voltage vector amplitude and space angle are calculated to obtain the action time of the first intermediate vector and the action time of the second intermediate vector, according to the action time of the first intermediate vector and the action time of the second intermediate vector. Time calculation to obtain the action time of the first voltage vector, the action time of the second voltage vector, the action time of the third voltage vector and the action time of the fourth voltage vector that synthesized the second intermediate vector ; Based on the principle of minimum switching loss, the order of action of the first voltage vector, the second voltage vector, the third voltage vector, and the fourth voltage vector is allocated to ensure any operation of the six-phase inverter system. A switching device has only one on-off in one cycle; A modulated wave is generated according to the action time and action order of the first voltage vector, the second voltage vector, the third voltage vector and the fourth voltage vector, and the sawtooth wave is used as the carrier wave. The carrier waves are compared to generate a PWM control signal of the six-phase inverter system, and the current control of the six-phase inverter system is realized according to the PWM control signal. 2 . The control method for suppressing the fifth harmonic current of a six-phase motor according to claim 1 , wherein the reference voltage vector

The magnitude of

and the spatial angle θ can be determined according to

to obtain, where U _α is the component of the reference voltage vector in the α direction, and U _β is the component of the reference voltage vector in the β direction. 3 . The control method for suppressing fifth harmonic current of a six-phase motor according to claim 1 , wherein the method for obtaining the maximum amplitude voltage vector output by the six-phase inverter system specifically comprises: calculating and obtaining the The fundamental wave space voltage vector and the fifth harmonic space voltage vector of the six-phase inverter system are calculated and obtained according to the fundamental wave space voltage vector and the fifth harmonic space voltage vector to obtain the maximum amplitude voltage vector. 4 . The control method for suppressing the fifth harmonic current of a six-phase motor according to claim 3 , wherein the fundamental wave space voltage vector and the fifth harmonic space voltage vector can be determined according to the

Calculated to obtain, where,

is the fundamental space voltage vector;

is the 5th harmonic space voltage vector; U _dc is the DC bus voltage,

U _dc is the DC bus voltage. 5 . The control method for suppressing the fifth harmonic current of a six-phase motor according to claim 4 , wherein the maximum amplitude voltage vector V _max can be determined according to the

obtain, where V _max is the large vector magnitude; V _midl is the next largest vector magnitude; V _mids is the next small vector magnitude; and V _min is the small vector magnitude. 6 . The control method for suppressing the fifth harmonic current of a six-phase motor according to claim 1 , wherein, according to the first intermediate vector and the second edge of the first edge of the sector where the reference voltage vector is located. 7 . The reference voltage vector synthesized by the second intermediate vector based on the volt-second equivalent principle is:

Among them, T' ₁ is the action time of the first intermediate vector, T' ₂ is the action time of the second intermediate vector,

is the second intermediate vector, T _s is the sampling cycle time,

Zero vector, T' ₀ zero vector action time. 7 . The control method for suppressing the fifth harmonic current of a six-phase motor according to claim 6 , wherein the action time of the first intermediate vector and the action time of the second intermediate vector are: 8 .

in,

is the intermediate vector. 8 . The control method for suppressing fifth harmonic current of a six-phase motor according to claim 1 , wherein the first voltage vector, the second voltage vector, the third voltage vector and the first voltage vector The action time of the four voltage vectors is

Among them, T1 is the action time of the _first voltage vector, T2 is the action time of the _second voltage vector, T3 is the action time of the _third voltage vector, and T4 is the action time of the _fourth voltage vector. 9 . A six-phase inverter system, characterized in that, the six-phase inverter system uses the control method for suppressing fifth harmonic current of a six-phase motor according to any one of claims 1 to 9 to perform current control . 10 . The six-phase inverter system according to claim 9 , wherein the six-phase inverter system includes six inverter units connected in parallel, and any one of the inverter units includes two power switching devices IGBTs. 11 . .

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