CN105391265B - A kind of composite excitation fault-tolerant motor system of brushless harmonic exitation - Google Patents

Abstract

The invention discloses a brushless harmonic excitation hybrid excitation fault-tolerant motor system, by adding a harmonic winding (8); the excitation winding and the harmonic winding are set in the rotor slot, and both are concentrated windings; The harmonic windings in the two radially opposite rotor slots are connected in series to form one phase; after the harmonic windings of each phase are connected in parallel, they are connected to the excitation winding through a rectifier circuit to supply power to the excitation winding. In the motor system of the present invention, an excitation winding, a harmonic winding and a rectifier are added to the rotor structure, and brushes and slip rings are omitted, which is beneficial to further improving the reliability and power density of the motor. At the same time, the permanent magnets in the rotor are arranged in a "V" shape. The permanent magnets have both radial magnetization and tangential magnetization, which effectively concentrates the magnetic flux and improves the output of the motor. At the same time, it has a wide speed range, power density and efficiency. Advanced advantage.

Description

A hybrid excitation fault-tolerant motor system with brushless harmonic excitation

technical field

The invention relates to a motor, in particular to a hybrid excitation fault-tolerant motor based on brushless harmonic excitation.

Background technique

The rotor permanent magnet type built-in permanent magnet synchronous motor has the advantages of large torque output, wide speed range, high power density and high efficiency, and has been widely used in many high-performance drive fields. In the high-performance drive fields such as new energy electric vehicles, wind power generation and aerospace, high requirements are placed on the reliability of the drive system. However, the traditional built-in permanent magnet synchronous motor still has the problem of poor fault tolerance and cannot meet the system reliability requirements. In order to overcome this shortcoming, some experts and scholars at home and abroad have proposed a fault-tolerant motor, which can realize the isolation of the circuit, magnetic circuit and temperature field between the phases of the motor, and improve the fault-tolerant operation capability of the motor. However, the excitation magnetic field of this motor is generated by permanent magnets, and the adjustment of the air gap magnetic field cannot be realized. Hybrid excitation motors are favored by researchers at home and abroad because they can effectively solve such problems. At present, for the rotor permanent magnet type hybrid excitation motor, according to the position of the excitation winding, it can be divided into two types: the excitation winding in the stator part and the excitation winding in the rotor part. The first type of motor does not need brushes and slip rings, and has high reliability, but the structure of the motor is complex, there is an additional air gap, there are both radial flux and axial flux, and the power density and efficiency are low; the structure of the second type of motor It is relatively simple, but since the excitation winding is on the rotor, DC power needs to be supplied through an external power supply, and brushes and slip rings are required, which is not conducive to the high reliability of the motor. In order to solve the above problems, it is necessary to develop a hybrid excitation fault-tolerant motor system based on brushless harmonic excitation to meet the requirements of the drive system for the motor's high efficiency, strong fault tolerance, easy processing and brushless.

Contents of the invention

In view of the above existing technologies and their shortcomings, the present invention proposes a hybrid excitation fault-tolerant motor system based on brushless harmonic excitation, which solves the problems of poor fault-tolerant operation performance, permanent magnet demagnetization and excitation adjustment existing in traditional built-in permanent magnet synchronous motors Problems, while improving the efficiency and torque density of the motor, and can achieve brushless, to ensure the high reliability of the motor operation.

To achieve the above object, the technical solution adopted in the present invention is:

Compared with the prior art, the present invention has the following beneficial effects:

(1) The permanent magnets in the rotor are arranged in a "V" shape. The permanent magnets have both radial magnetization and tangential magnetization, which effectively concentrates the magnetic flux and improves the output of the motor. At the same time, it has a wide speed range and high power density. and high efficiency advantages;

(2) Use high-order harmonics to cut harmonic windings to generate induced electromotive force, and then rectify through diode rectification circuits to supply power to the excitation windings, without brushes and collector rings, and AC excitation motors, with simple structure and high reliability;

(3) The excitation winding is installed in the rotor slot, there is no axial magnetic circuit and additional air gap, which maintains the high power density and high efficiency of the permanent magnet motor;

(4) The armature winding on the stator is a centralized winding with short ends for easy installation, and the fault-tolerant teeth without winding are used as the magnetic flux circuit, and at the same time, the isolation of the circuit, magnetic circuit and temperature field between the motor phases is realized , improving the reliability and fault-tolerant operation capability of the motor;

(5) Redundant electric excitation is adopted. When the permanent magnet loses excitation, the excitation magnetic field generated by the electric excitation winding can be used to maintain the operation of the motor, which improves the fault tolerance of the motor.

Description of drawings

Fig. 1 is the schematic diagram of motor structure of the present invention;

Among them: 1 stator, 2 rotor, 3 permanent magnet, 4 armature teeth, 5 fault tolerance teeth, 6 armature winding, 7 excitation winding, 8 harmonic winding.

Figure 2 is a schematic diagram of unequal air gap design;

Where: ω is the angular velocity of the rotor, R _s is the inner radius of the stator, R _r is the outer radius of the rotor, and h is the centrifugal height.

Figure 3 shows the harmonic analysis of the air-gap magnetic density when the armature winding is fed with five-phase alternating current.

Fig. 4 is a block diagram of the circuit structure of the hybrid excitation fault-tolerant motor system with brushless harmonic excitation according to the present invention.

Fig. 5 shows the connection mode of the rotor harmonic winding in the present invention.

Fig. 6 shows the connection mode of the rotor excitation winding in the present invention.

detailed description

The technical scheme of the present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 1, a five-phase hybrid excitation fault-tolerant motor based on brushless harmonic excitation includes stator 1, rotor 2, permanent magnet 3, armature teeth 4, fault-tolerant teeth 5, armature winding 6, and field winding 7 and harmonic winding8. The armature teeth 4 and the fault-tolerant teeth 5 are evenly distributed along the inner ring of the stator 1, the total number of teeth is a multiple of 2m (m is the number of phases of the motor), and the tooth width of the armature teeth 4 and the tooth width of the fault-tolerant teeth 5 are different. equal. The armature teeth 4 are wound with armature windings 6, which are single-layer concentrated windings, and two adjacent single-layer concentrated windings are isolated by fault-tolerant teeth 5, which provide magnetic flux circuits and at the same time achieve phase-to-phase magnetic isolation and physical The function of isolation, thermal isolation and electrical isolation fundamentally avoids short circuit between phases, has high reliability and ability to operate with faults, and reduces torque ripple. The permanent magnet 3 is embedded in the rotor 2 and has a "V" shape. In this way, the permanent magnet has both radial magnetization and tangential magnetization, which effectively concentrates the magnetic flux and can increase the torque of the motor. The difference between the total number of teeth of the armature teeth 4 and the fault-tolerant teeth 5 and the number of pole pairs of the permanent magnet 3 is ±2. The excitation winding 7 and the harmonic winding 8 are set in the rotor slot, and both are concentrated windings. The harmonic winding 8 is connected to the excitation winding 7 through a diode rectifier circuit; the coils of the excitation winding 7 are connected in series from end to end; all permanent magnets 3 form a permanent magnetic field , all excitation coils constitute the electric excitation magnetic field.

The distance between the inner circumference of the stator 1 and the outer circumference of the rotor 2 is unequal. In the present invention, the radians of the inner circumference of the armature teeth 4 and the tolerance teeth 5 on the stator 1 are larger than the radians of the outer circumference of the rotor 2 . As shown in Figure 2, the inner radius of the stator 1 is larger than the outer radius of the rotor 2; at the same time, the distance between the center of the inner arc of the stator 1 and the center of the outer arc of the rotor 2 is h, which is defined as the centrifugal height. This results in an uneven air gap between the rotor 2 and the stator 1 . Along the counterclockwise rotation direction of the rotor, the air gap length changes from the minimum value to the maximum value within one cycle. Therefore, the armature magnetic field is weakened where the air gap is larger, while being compensated for where the air gap is smaller. Therefore, the air gap flux density distortion and torque ripple will be well suppressed. The back EMF distortion and torque ripple can be minimized by optimizing the centrifugal height h and the tooth width of the armature tooth and the tolerance tooth. When the armature winding is fed with five-phase AC current, the air gap magnetic density is shown in Figure 3, and there are mainly 9th and 11th harmonics.

When the motor runs below the base speed, the permanent magnet works alone, and only the permanent magnetic field exists; when the motor runs above the base speed, the harmonic winding is connected, and the permanent magnet and the excitation winding work together to realize the adjustment of the permanent magnetic field. Utilize the uneven air gap and unequal stator tooth width to optimize the air gap magnetic density so that only a certain high-order harmonic exists, and use the high-order harmonic to cut the harmonic winding to generate induced electromotive force, and then rectify through the diode rectifier circuit, Power is supplied to the field winding, and the magnetic field generated by the DC field winding is equal to the number of poles of the permanent magnetic field to realize the adjustment of the air gap magnetic field. When the permanent magnet has a demagnetization failure, the harmonic winding is connected, and the excitation magnetic field generated by the electric excitation winding can also be used to maintain the operation of the motor and improve the fault tolerance of the motor.

The working principle of the present invention is as follows: the motor generates the main magnetic field jointly by two kinds of excitation sources, permanent magnet excitation and electric excitation. Potential source. When the motor runs below the base speed, the rotor winding does not work, and the permanent magnet acts alone. When the motor runs above the base speed, the rotor winding and the permanent magnet work together to cut the harmonic winding 8 by using the high-order harmonic in the air-gap magnetic density to generate the induced electromotive force, which is then rectified by the diode rectifier circuit, and the DC excitation winding generates The poles of the magnetic field and the permanent magnetic field are equal to realize the adjustment of the permanent magnetic field.

The principle that the harmonic winding of the present invention produces the induced harmonic electromotive force is:

As shown in Figure 3, the harmonic analysis of the air-gap magnetic density when the armature winding is fed with five-phase AC current, it can be seen from the figure that the main high-order harmonics in the air-gap magnetic density are the 9th and 11th, among which, The 9th harmonic is the main working harmonic and is used to generate torque, while the 11th harmonic is used to excite the field winding. The circuit structure diagram of the hybrid excitation fault-tolerant motor system with brushless harmonic excitation is shown in Figure 4. The external power supply device supplies power to the armature winding, and the 11th harmonic in the air gap cuts the harmonic winding installed on the rotor to generate induced electromotive force. , the induced potential is rectified into direct current by the rectifier circuit, which supplies power to the excitation winding. This eliminates the brushes and slip rings of conventional hybrid excitation motors with field windings on the rotor. The connection mode of the harmonic winding is shown in Figure 4, the harmonic windings in the two radially opposite rotor slots are connected in series to form a phase. The nine-phase harmonic winding is connected to the excitation winding through a rectifier circuit. The connection method of the excitation winding is shown in Figure 5. The coils of the excitation winding are connected in series from end to end. The specific reasons are as follows:

The rotation speed of the higher harmonic is different from the synchronous speed of the fundamental wave. Similar to the asynchronous motor, the slip rate of the υ harmonic is:

Among them, ^υ ω _S ＝ω _S /υ, ω _S is the electrical angular frequency of the stator; ω _R is the electrical angular frequency of the rotor magnetic field; s is the slip before harmonics are used,

When the rotor pole pitch is equal, the induced flux linkage of single-turn field winding is:

in, is the flux density of the υ-order harmonic, ^υ ξ _ψ is the coupling factor between the υ-order harmonic and the rotor excitation winding, l is the axial length of the armature, and τ is the rotor pole pitch.

Among them, P _R is the number of rotor pole pairs.

When the excitation winding coils are connected in series, according to formula (2), the induced flux linkage in the kth coil is:

From the formula (4) and Figure 6, it can be known that the sum of the induced flux linkage of the excitation winding is:

Solving formula (5), the induced flux linkage of the rotor excitation winding is obtained as:

υ＝(2g-1)·P _R g＝1,2,3,…

It can be seen from formulas (6) and (7) that when all the excitation winding coils are connected in series, only working harmonics exist in the rotor winding, although there are non-working harmonics in each coil of the rotor (υ≠(2g-1 ) · P _R ), but when they are connected in series, these harmonics cancel each other out in the induced flux linkage.

Therefore, the induced electromotive force generated in the harmonic winding is rectified by the diode rectifier circuit, and the magnetic field generated by the DC excitation winding is equal to the number of poles of the permanent magnetic field to realize the adjustment of the permanent magnetic field.

The motor system of the present invention retains the advantages of the traditional built-in permanent magnet synchronous motor in terms of structure and performance, such as large torque output, wide speed range, high power density and high efficiency; One excitation method solves the difficult problems of permanent magnet demagnetization and excitation adjustment; on the stator structure, the use of single-layer concentrated armature winding can improve the fault tolerance performance of the motor; on the rotor structure, adding excitation winding, harmonic winding and rectifier saves The removal of brushes and slip rings is conducive to further improving the reliability and power density of the motor.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (4)

1. A brushless harmonic excited hybrid excitation fault-tolerant motor system comprises a stator (1), a rotor (2), a permanent magnet (3), armature teeth (4), fault-tolerant teeth (5), an armature winding (6) and an excitation winding (7); the armature teeth (4) and the fault-tolerant teeth (5) are uniformly distributed along the circumferential direction of the inner ring of the stator (1) at intervals, and the tooth width of the armature teeth (4) is not equal to that of the fault-tolerant teeth (5); armature windings (6) of single-layer concentrated windings are wound on the armature teeth (4), and two adjacent single-layer concentrated windings are isolated by the fault-tolerant teeth (5); the permanent magnets (3) are embedded into the rotor (2), and all the permanent magnets (3) form a permanent magnetic field; the method is characterized in that: also comprises a harmonic winding (8); the excitation winding (7) and the harmonic winding (8) are sleeved in the rotor slot and are both concentrated windings; the coils of the excitation winding (7) are sequentially connected in series end to form an electric excitation magnetic field; the harmonic windings (8) in two diametrically opposite rotor slots are connected in series to form one phase; the harmonic windings (8) of all phases are connected in parallel and then are connected with the excitation winding (7) through a rectifying circuit; the distance between the stator (1) and the rotor (2) is not equal.

2. The brushless harmonically excited hybrid-excitation fault-tolerant motor system of claim 1, wherein: the inner circumference radian of the stator (1) is larger than the outer circumference radian of the rotor (2).

3. The brushless harmonically excited hybrid-excitation fault-tolerant motor system of claim 1, wherein: armature tooth (4) with the total number of teeth of tolerance tooth (5) is the multiple of 2m, and armature tooth (4) with the total number of teeth of tolerance tooth (5) with the difference of the number of pole pairs of permanent magnet (3) is 2, wherein m is the phase number of motor.

4. The brushless harmonically excited hybrid-excitation fault-tolerant motor system of claim 1, wherein: the permanent magnet (3) is embedded into the rotor (2) and is V-shaped.