CN104052180B - A kind of multiple symmetric winding flux switch motor and design of Windings method thereof - Google Patents

Abstract

The invention discloses a magnetic flux switching motor with multiple symmetrical windings and a winding design method thereof. On the basis of giving full play to the complementarity of the windings of the magnetic flux switching motor, the method is based on the principle of maximizing the induced potential of each phase, and by optimizing two adjacent According to the phase difference between sets of symmetrical windings, the coil composition of one phase winding, the coil composition of a set of symmetrical windings and the coil connection form of all phase windings are obtained in sequence. The winding design method of the present invention is clear in thinking and easy to operate. The magnetic flux switching motor with multiple symmetrical windings of the present invention has the characteristics of high no-load induced potential sine degree, high winding utilization rate, large torque output and small electromagnetic torque ripple, reflecting the Superior motor performance.

Description

A magnetic flux switching motor with multiple symmetrical windings and its winding design method

technical field

The invention belongs to the field of motor winding structure design, and relates to a magnetic flux switching motor with multiple symmetrical windings and a winding design method thereof.

Background technique

The flux switching permanent magnet motor has the characteristics of high torque (power) density, high efficiency, and solid rotor structure, and is especially suitable for high-performance drive and high-speed applications. With the continuous improvement of performance requirements for the power level, fault-tolerant operation and reliability of the motor system in the application, the multi-phase flux switching permanent magnet motor has increasingly become a key topic for universities and research institutions at home and abroad, because it not only It retains the advantages of ordinary three-phase flux switching permanent magnet motors, and also has significant advantages in the following four aspects:

(1) In high-power applications, the power level allocated by each phase winding is within the acceptable range of the power device, so that the standard power module can be used directly.

(2) Reliability is improved. For a symmetrical m-phase motor, the phase difference between two adjacent phase vectors is 2π/m. When a phase winding fails, the power loss caused by the fault phase accounts for a small proportion of the total, which enhances the fault tolerance performance of the motor; for a multi-phase motor composed of x sets of n-phase symmetrical windings with independent neutral points, when a certain When a phase winding fails, the set of n-phase symmetrical windings where the phase winding is located is directly cut off, so that the motor can still operate normally without changing the control algorithm.

(3) As the number of phases increases, the amplitude of the space harmonic magnetic field caused by the armature winding current provided by the inverter decreases, thereby reducing the torque ripple.

(4) The frequency of the cogging torque can be effectively increased through the specific cogging of the stator and the rotor, thereby reducing the amplitude of the cogging torque and reducing the torque ripple of the motor.

However, torque ripple is an unavoidable problem in permanent magnet motors. The main causes of torque ripple are: positioning torque, no-load induction potential harmonics of each phase, reluctance torque caused by direct axis and quadrature axis inductance changes And loaded armature current waveform distortion, etc.

The existing winding design methods of flux switching motors only design the connection of the armature winding coils of each phase according to the slot conductor potential star diagram and the principle of winding complementarity, and finally design the multiple symmetrical windings into a completely symmetrical distribution structure. This method can reduce the harmonic component of the induced potential to a certain extent, thereby increasing the sine degree of the induced potential of each phase, but there are still the following problems: the harmonic induced potential cannot be completely eliminated, so the torque ripple caused by the harmonic induced potential still exist; even if the harmonic induction potential is negligible, the torque ripple caused by the harmonic component of the armature current is still relatively serious; it cannot be guaranteed that each phase no-load induction potential has a high winding factor, which affects each phase The amplitude of the fundamental wave component of the no-load induction potential and the output of the motor.

Contents of the invention

Technical problem: The present invention provides a winding no-load induced potential total harmonic distortion rate is small, the average value of electromagnetic torque is high, and can effectively suppress the odd harmonic components caused by no-load induced potential or armature current A magnetic flux switching motor with multiple symmetrical windings induced by electromagnetic torque ripple, and a winding design method for the motor is provided.

Technical solution: The multi-symmetrical winding flux switching motor winding design method of the present invention is designed for x sets of n-phase symmetrical windings of a multi-phase flux switching motor, including the following steps:

1) Determine the number of coils per phase as N/m according to the total number of phases m of the motor winding and the total number of coils N, and then connect the two coils with complementary windings to form a coil group, and the phase difference of the induced potential is the smallest N/(2m) coil groups are connected to form a phase winding, so as to obtain the coil composition of the first phase winding, wherein the total number of armature winding coils N is an even multiple of the total phase number m, that is, N=2km, and k is a positive integer ;

2) According to the phase relationship between the phase windings in the n-phase symmetric windings, that is, the phase difference between the adjacent two-phase windings in a set of n-phase symmetric windings is 2π/n, it is determined to be in the same phase as the first phase winding Set of coils of other n-1 phase windings of symmetrical windings, so as to obtain the composition of the first set of n-phase symmetrical windings;

3) Determine the phase difference θ _set between two adjacent sets of n-phase symmetrical windings according to the following formula:

Wherein, x is the number of n-phase symmetrical windings in the flux switching motor with multiple symmetrical windings, and both x and n are integers greater than 1.

4) According to the phase difference θ _set determined in the step 3), and the phase relationship (i-1) θ _set between other symmetrical windings and the first set of symmetrical windings, the coil composition of other x-1 sets of symmetrical windings is sequentially determined, Wherein i is the serial number of the symmetrical winding, the serial number of the first set of symmetrical windings is i=1, and the serial numbers of the other x-1 sets of symmetrical windings are i=2, 3, . . . , x.

In the method of the present invention, in step 1), when two coils with winding complementarity are connected into a coil group, if the no-load induced potential phase difference of the two complementary coils is 180°, reverse series connection; if the two complementary coils The phase difference of the no-load induction potential of the coil is 0°, so it is forward connected in series.

The magnetic flux switching motor with multiple symmetrical windings of the present invention adopts x sets of n-phase symmetrical windings, and the phase difference θset between two adjacent _sets of n-phase symmetrical windings is:

Among them, x is the number of n-phase symmetrical windings in the multiple symmetrical winding flux switching motor, x and n are both integers greater than 1, the total number of phases of the motor is m=xn, and the total number of coils N is an even number of the total number of phases times, ie N=2km, k is a positive integer.

In the magnetic flux switching motor with multiple symmetrical windings of the present invention, the n-phase symmetrical windings are formed by connecting N/(2m) coil groups with the smallest induced potential phase difference, and the coil groups are formed by connecting two coils with complementary windings.

In the above preferred scheme of the multiple symmetrical winding flux switching motor of the present invention, if the no-load induced potential phase difference of the two complementary coils is 180°, reverse series connection; if the no-load induced potential phase difference of the two complementary coils is 0 °, then forward in series.

The method of the invention is used to guide the winding coil connection, the composition form of each phase winding and the selection of the phase difference between x sets of n-phase symmetrical windings. The maximum pulsation component of the electromagnetic torque of each set of n-phase symmetrical windings is offset, and the torque pulsation of the multi-phase flux switching permanent magnet motor is reduced. The invention aims at improving the winding factor of the motor and the sinusoidality of the no-load induced potential while reducing the torque ripple. Hybrid excitation motor.

Beneficial effects: Compared with the prior art, the present invention converts the design of multi-phase windings into the design of multiple symmetrical windings on the basis of considering the potential star diagram of slot conductors and the complementarity of windings. In the present invention, the distribution of multi-phase windings is no longer limited to a completely symmetrical structure, but by deriving the relationship between the torque ripple and the phase difference between two adjacent sets of symmetrical windings, in order to eliminate the maximum torque ripple component, Obtaining the optimal phase difference enables the motor to achieve the following advantages:

1) Complementary connection is adopted, so that the even harmonic components of the no-load induced potential of each phase winding are basically offset, and the remaining odd harmonic components are small, so that the total harmonic distortion rate of the no-load induced potential of each phase winding is small , correspondingly reduce the torque ripple component caused by harmonics;

2) Each phase winding is connected by the coil group with the smallest phase difference of the induced potential, so the fundamental winding factor of the no-load induced potential of each phase winding is high, close to 1, so that the amplitude of the fundamental component of the no-load induced potential of each phase can be obtained Effectively improve, thereby increasing the average value of the electromagnetic torque of the motor;

3) The phase difference between two adjacent sets of n-phase symmetrical windings is uniquely determined by the phase number n and the number x of symmetrical windings, and the calculation formula is simple and clear, and the winding design steps are easy to operate;

4) By rationally designing the phase difference between two adjacent sets of n-phase symmetrical windings, the electromagnetic torque ripple caused by the odd harmonic component in the no-load induced potential is further suppressed, reducing the vibration of the motor, thereby improving the operation of the motor stability;

5) By rationally designing the phase difference between two adjacent sets of n-phase symmetrical windings, the torque ripple caused by the odd harmonic component of the loading current in the armature winding is effectively suppressed. Because the armature current is supplied by the inverter to the armature winding of the motor, there are inevitably harmonic components in it, which seriously affect the stability of the motor torque output. The winding design method of the present invention can suppress or eliminate the torque ripple caused by the odd harmonic component in the armature current, effectively improve the torque quality of the motor, and reduce the requirements for the output characteristics of the inverter. control brings convenience.

Description of drawings

Fig. 1(a) is a schematic cross-sectional structure diagram of a permanent magnet motor with 24 slots in the stator and a 22-pole flux switching type permanent magnet motor.

Figure 1(b) is a star diagram of the no-load induced potential of the slot conductor of a permanent magnet motor with 24 slots in the stator and a 22-pole flux switching permanent magnet motor. Among them, the polarity of coil n' is opposite to that of n, and the potential vector phase difference of adjacent slot conductors is 150° (electrical angle).

Figure 2(a) shows the winding vector distribution of two sets of three-phase symmetrical windings with a mutual difference of 30° for a permanent magnet motor with 24 slots in the stator and a 22-pole flux switching permanent magnet motor.

Figure 2(b) shows the winding vector distribution of two sets of three-phase symmetrical windings with a mutual difference of 60° for a permanent magnet motor with 24 slots in the stator and a 22-pole flux switching permanent magnet motor.

Fig. 3 is the torque characteristics of a flux-switching permanent magnet motor with 24 slots in the stator and 22 poles in the rotor under the two winding distributions in Fig. 2 .

detailed description

The present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

A magnetic flux switching motor with multiple symmetrical windings of the present invention includes a stator 1, a rotor 4 and a rotating shaft 5, the rotor 4 is opposite to the stator 1, and there is a gap between the rotor 4 and the stator 1, and the rotating shaft 5 is fixedly connected to the rotor 4. Both the stator 1 and the rotor 4 are salient pole structures. The stator 1 includes a stator core unit and a concentrated armature winding coil 2 . Each stator core unit includes two U-shaped stator cores 101 and a permanent magnet 3 embedded between the two U-shaped stator cores 101 . The permanent magnets 3 are magnetized tangentially, and the directions of magnetization of two adjacent permanent magnets 3 are opposite. A stator slot 102 is formed between two adjacent stator core units. The concentrated armature winding coil 2 passes through the stator slots 102 on both sides of the stator core unit and is wound on the stator core unit. The number of armature winding coils 2 is equal to the number of stator core units. The stator and rotor cores are made of magnetically permeable materials. The permanent magnet 3 is made of permanent magnet material, preferably NdFeB, ferrite, or samarium cobalt.

Further, the total number N of armature winding coils 2 is an even multiple of the total phase number m, that is, N=2km, and k is a positive integer.

Further, the rotor 4 can be located inside the stator 1 or outside the stator 1 .

Further, the flux switching motor with multiple symmetrical windings can be a pure permanent magnet excitation motor, a pure electric excitation motor, or a hybrid excitation motor, including an online charging and demagnetization memory motor, and the motor can be used for power generation , and can be used for electric operation.

Different from the traditional flux switching motor, the multi-symmetric winding flux switching motor proposed by the present invention can decompose the armature winding into x sets of n-phase symmetrical windings. The total number of phases of the motor is m=xn, where x and n are greater than An integer of 1, so the motor is also called an x-heavy n-phase symmetrical winding flux switching motor.

The innovation of the present invention is: the x-fold n-phase symmetrical winding of the magnetic flux switching motor adopts the winding design method disclosed in the present invention, and the specific implementation plan is as follows:

1) Firstly, according to the total number of phases m and the total number of coils N, the number of coils in each phase is determined as N/m, usually every two coils are connected to form a coil group, then the number of coil groups in each phase is N/(2m ). Based on the potential star diagram of the slot conductor, every two coils with winding complementarity are connected in series to form a coil group (if the no-load induced potential phase difference of the two complementary coils is 180°, reverse series connection; if the two complementary coils The phase difference of the no-load induced potential is 0°, then it is forward connected in series), thus forming a total of N/2 coil groups, and the phase difference of the induced potential of the two coils in each coil group is 0° or 180°, so The distribution factor of the fundamental wave component of the induced potential of the coil group is 1, and the even harmonic components in the induced potential of a single coil cancel each other, so that the harmonic content of the no-load induced potential of the coil group is reduced; then the induced potential of each phase winding is the largest In principle, the N/(2m) coil groups with the smallest phase difference in the induced potential of the coil groups are connected into a phase winding, so as to obtain the coil composition of the first phase winding.

2) According to the phase relationship between the phase windings in the n-phase symmetric windings, that is, the phase difference between the adjacent two-phase windings in a set of n-phase symmetric windings is 2π/n, it is determined to be in the same phase as the first phase winding The coils of the other n-1 phase windings of the set of symmetrical windings are formed, so as to obtain the composition of the first set of n-phase symmetrical windings.

3) Determine the phase difference between two adjacent sets of n-phase symmetrical windings. From the electromagnetic torque formula of x sets of n-phase symmetrical windings, it can be known that the torque ripple component is related to the phase difference between two adjacent sets of symmetrical windings. In order to simplify the derivation process, only the torque ripple caused by the induced potential or the odd harmonic of the armature current is considered here, and the ripple component with a small amplitude is ignored.

The pulsating component T _pulse of the electromagnetic torque of the n-phase symmetrical winding can be expressed as:

Among them, T _2kn is the amplitude of the 2kn times torque ripple component, θ is the electrical angle of the rotor position, is the initial phase angle of the 2kn torque ripple component.

Then the pulsating component T _{pulse_x} of the total electromagnetic torque of x sets of n-phase symmetric windings can be expressed as the superposition of the electromagnetic torque pulsation components of x sets of n-phase symmetric windings:

It can be seen from the above formula that the phase difference of the 2kn times pulsating component of the electromagnetic torque of two adjacent sets of n-phase symmetrical windings is 2knθ _set . To make the 2kn torque ripple components of group x cancel each other out, the 2knθ _set should satisfy the following relationship:

In order to eliminate the maximum torque ripple component, that is, the 2nth torque ripple component when k=1, the optimal phase difference θ _set between two adjacent sets of symmetrical windings can be simplified by the above formula:

It shows that when the phase angle difference between two adjacent sets of symmetrical windings satisfies (4), the maximum ripple component of electromagnetic torque in each set of n-phase symmetrical windings can be offset.

4) According to the phase difference calculated in (4), and the phase relationship (i-1)θ _set between other symmetrical windings and the first set of symmetrical windings, determine the coil composition of other x-1 sets of symmetrical windings in turn, where i is The serial numbers of the symmetrical windings, the serial numbers of the first set of symmetrical windings are i=1, and the serial numbers of the other x-1 sets of symmetrical windings are i=2,3,...,x.

Designing multiple symmetrical windings of a multi-phase flux switching motor according to the above process can not only ensure that the motor obtains a phase no-load induced potential with a higher sinusoidal degree, but also make the winding factor larger, increase the average value of the electromagnetic torque, and reduce the The pulsation rate of the small electromagnetic torque can obtain higher quality torque output.

Taking the flux-switched permanent magnet motor with dual three-phase symmetrical windings as an example, its common motor topology is shown in Figure 1(a). There are 24 centralized armature winding coils on the stator, which are armature winding coils 201, 202, 203, ..., 224. These 24 coils are designed in the form of 6-phase windings, and can be decomposed into two sets of three-phase symmetrical windings, ie m=6, x=2, n=3. The specific winding design process is as follows:

1) According to the total number of phases m=6 and the total number of coils N=24, the number of coils in each phase winding is determined to be 4, and the number of coil groups in each phase is 2. According to the slot conductor potential star diagram of the stator 24-slot rotor 22-pole flux switching permanent magnet motor, as shown in Fig. ) and coil 207 (coil 219), coil 202 (coil 214) and coil 208 (coil 220), coil 203 (coil 215) and coil 209 (coil 221), coil 204 (coil 216) and coil 210 (coil 222) , coil 205 (coil 217) and coil 211 (coil 223), coil 206 (coil 218) and coil 212 (coil 224), the phase difference of the two coil no-load induced potentials in each above-mentioned coil combination is 180 °, through Reverse series, connect two complementary coils into a coil group, each coil cannot be combined repeatedly, then a total of 12 mutually independent coil groups are formed, namely coil 201 and coil 207, coil 202 and coil 208, coil 203 and Coil 221, Coil 204 and Coil 222, Coil 205 and Coil 211, Coil 206 and Coil 212, Coil 213 and Coil 219, Coil 214 and Coil 220, Coil 215 and Coil 209, Coil 216 and Coil 210, Coil 217 and Coil 223 , coil 218 and coil 224 . In order to ensure that the distribution factor of the fundamental wave component of the induced potential of the phase winding is closest to 1, the two coil groups with the smallest potential vector phase difference are connected to form a phase winding. It can be seen from observation that the potential vector phase difference between the coil group 201+207' and the coil group 213+219' is 0°, then the distribution factor of the fundamental wave component of the induced potential of the phase winding formed by the two coil groups connected in series is 1. The phase winding is A1.

2) In the three-phase symmetrical winding, the B1 and C1 phase windings are respectively +120° and -120° electrical angle different from the A1 phase winding, so the coil composition of the B1 and C1 phase windings can be easily obtained, as shown in Figure 2(a) shown. Thus, the coil connection mode of the first set of three-phase symmetrical windings A1, B1, and C1 is determined. In order to reflect the advantages of the winding design method of the present invention, the A1 phase winding connection forms obtained according to the prior art are listed here, as shown in Figure 2 (b), the A1 phase is composed of coil groups 201+207' and coil groups 208+ 202', the potential vector phase difference of these two coil groups is 30° electrical angle, so the distribution factor of the A1 phase induced potential fundamental wave component is 0.966, which is lower than the A1 phase winding distribution factor designed according to the present invention.

3) Determine the phase difference θ _set between the two sets of three-phase symmetrical windings. In the following, through theoretical analysis, taking a flux-switched permanent magnet motor with double three-phase symmetrical windings as an example, the optimal phase difference between its two sets of three-phase symmetrical windings is deduced.

For a three-phase symmetrical AC synchronous motor, the electromagnetic torque expression is as follows:

Among them: T ₀ is the DC amount of electromagnetic torque, that is, the average electromagnetic torque, T _6k is the amplitude of 6k torque ripple components, θ is the electrical angle of the rotor position, is the initial phase angle of the 6k torque ripple component. It can be seen that the electromagnetic torque consists of an average torque component and a multiple of 6 harmonic torque components.

For a double three-phase symmetrical winding flux switching permanent magnet motor, its electromagnetic torque can be expressed as the electromagnetic torque superposition of two three-phase symmetrical winding motors:

Using the sum-difference product formula for (6), we can get:

It can be known from formula (7) that when cos(3kθ _set )=0, 6k torque ripple components can be eliminated. Therefore, in order to minimize the torque ripple, the maximum torque ripple component T ₆ can be offset, and θ _set =30° can be easily obtained. Therefore, in the dual three-phase symmetrical winding flux switching permanent magnet motor, when the phase difference between the two sets of three-phase windings is 30°, the 6th pulsation component of the electromagnetic torque is completely eliminated, and the torque pulsation is reduced by 12 The secondary pulsation is dominant, and the pulsation amplitude is very small.

4) The phase difference between another set of three-phase symmetrical windings A2, B2, and C2 and the first set of three-phase symmetrical windings A1, B1, and C1 is 30°, then A2 leads (or lags) A1 phase by 30°, and B2 leads (or lagging) B1 phase by 30°, C2 leading (or lagging) C1 phase by 30°. According to the potential star diagram of the slot conductor, the coil composition of the A2, B2, and C2 phase windings can be easily determined, as shown in Figure 2(a). Therefore, the connection form of the armature winding of the double three-phase symmetrical winding flux-switching permanent magnet motor is determined.

Fig. 2 (a) is the asymmetrical 6-phase winding distribution (winding design method of the present invention) of θ _set = 30°; Fig. 2 (b) is the symmetrical 6-phase winding distribution (existing winding design method) of θ _set = 60° method). In order to illustrate that the winding design method of the present invention has advantages compared with the existing winding design methods, Fig. 3 compares the electromagnetic torque waveforms of the dual three-phase symmetrical winding flux switching motor under the two winding design methods. Through comparison, it can be seen that when the phase difference of two sets of three-phase windings is 60°, the pulsation frequency of the electromagnetic torque is 6 times of the fundamental frequency, and the pulsation amplitude is relatively large; when the phase difference of the two sets of three-phase windings is 30°, the electromagnetic torque The pulsation frequency of the torque is 12 times of the fundamental frequency, the pulsation amplitude is very small, and the output force is larger, thereby verifying the theoretical analysis result of step 3), and reflecting that the winding design method of the multi-symmetric winding magnetic flux switching motor of the present invention is innovative sex and superiority.

The above are only preferred embodiments of the present invention, and it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some conceivable improvements and equivalent replacements can also be made, which are essential to the present invention. The technical solutions after the claims are improved and replaced by equivalents all fall into the protection scope of the present invention.

Claims (5)

1. the design of Windings method of a multiple symmetric winding flux switch motor, it is characterised in that, the method designs for the x cover symmetrical winding of n of heterogeneous flux switch motor, comprises the following steps:

1) determine that the coil number of every phase is N/m according to the total number of phases m of machine winding and the total number N of coil, then two coils with winding complementarity are connected into a coil assembly, N/ (2m) individual coil assembly minimum for induction electromotive force phase differential is connected into a phase winding, thus the coil obtaining the first phase winding is formed, wherein the total number N of armature winding coil is the even-multiple of total number of phases m, namely N=2km, k are positive integer;

2) according to phase relationship between each phase winding in the symmetrical winding of n, namely in the symmetrical winding of a set of n, phase differential between adjacent two phase windings is 2 ��/n, determine to form with the coil of described first phase winding at other n-1 phase windings of same set of symmetric winding, thus obtain the formation of the first symmetrical winding of cover n;

3) phase difference �� between the adjacent two cover symmetrical windings of n is determined according to following formula_set:

Wherein, x is the number of the symmetrical winding of n in multiple symmetric winding flux switch motor, and x, n are the integer being greater than 1;

4) according to described step 3) in the phase difference �� determined_set, and phase relationship (i-1) �� of other symmetric windings and the first cover symmetric winding_set, determine that other x-1 overlap the coil formation of symmetric winding successively, wherein i is the sequence number of symmetric winding, and the sequence number of the first cover symmetric winding gets i=1, and it is i=2,3 that other x-1 overlap the sequence number of symmetric winding ..., x.

2. design of Windings method according to claim 1, it is characterized in that, described step 1) in, when two coils with winding complementarity are connected into a coil assembly, if the unloaded induction electromotive force phase differential of two complementary coils is 180 ��, then oppositely connect; If the unloaded induction electromotive force phase differential of two complementary coils is 0 ��, then just to series connection.

3. a multiple symmetric winding flux switch motor, it is characterised in that, this motor adopts x to overlap the symmetrical winding of n, the phase difference �� between the adjacent two cover symmetrical windings of n_setFor:

Wherein, x is the number of the symmetrical winding of n in multiple symmetric winding flux switch motor, and x, n are the integer being greater than 1, total number of phases m=xn of motor, and the total number N of coil is the even-multiple of total number of phases, and namely N=2km, k are positive integer.

4. multiple symmetric winding flux switch motor according to claim 3, it is characterized in that, by responding to, electromotive force phase differential minimum N/ (2m) individual coil assembly connects into the symmetrical winding of described n, and described coil assembly is formed by connecting by two coils with winding complementarity.

5. multiple symmetric winding flux switch motor according to claim 4, it is characterised in that, if the unloaded induction electromotive force phase differential of two complementary coils is 180 ��, then oppositely connect; If the unloaded induction electromotive force phase differential of two complementary coils is 0 ��, then just to series connection.