CN100454729C - Two-way hybrid excitation brushless motor - Google Patents

Abstract

The two-way hybrid excitation brushless motor is a hybrid excitation speed-regulating motor that combines permanent magnets and electric excitation. The stator yoke and rotor yoke of the brushless motor adopt a double yoke structure; the stator outer yoke used for axial magnetization (9) and the rotor inner yoke (15) are annular cylinders, wherein the stator outer yoke (9) is divided into several equal parts by permanent magnets (16), the length of the stator outer yoke (9) and the rotor inner yoke (15) The length of the iron core laminated with silicon steel sheets is the same; the stator outer yoke (9) is inside the motor housing (4), the stator inner yoke (10) is located inside the stator outer yoke (9), and the stator inner yoke (10) is connected to the stator The outer yoke (9) together constitutes the stator yoke part of the double yoke structure; the rotor inner yoke (15) is tightly sleeved outside the rotating shaft (8), and the rotor inner yoke (15) is surrounded by the rotor outer yoke (14). (14) is provided with rotor teeth (13), and the rotor yoke part of the double yoke structure is jointly formed by the rotor inner yoke (15) and the rotor outer yoke (14).

Description

Two-way hybrid excitation brushless motor

technical field

The invention is a hybrid excitation speed-regulating motor combined with permanent magnet and electric excitation, which adopts a double-salient pole structure with axial and radial common excitation, and belongs to the technical field of brushless direct current motors.

Background technique

The traditional asynchronous motor has the advantages of simple structure, no maintenance and high reliability, and has been widely used in the field of ordinary motor drive, but its speed regulation performance is not good. Although frequency conversion technology or other control technologies can be used to achieve speed regulation, its cost is often relatively high, and the effect comparable to that of DC motors cannot be obtained. For ordinary DC motors, the armature winding current and the field winding current can be controlled separately, and the speed regulation performance is good. However, due to the brushes and commutators, the maintenance workload is large, and it is not suitable for high-speed and high-current operation, and the motor manufacturing cost is also high. high. The brushless DC motor, which has been studied more in recent years, has the advantages of long life, high reliability, high efficiency and high power density due to the cancellation of the sliding contact between the brush and the commutator. However, since the permanent magnet is installed on the rotor, Therefore, it is sensitive to ambient temperature and mechanical vibration, has low mechanical strength, is not suitable for high-speed operation, and sometimes causes demagnetization of permanent magnets due to armature reaction. Both the stator and the rotor of the switched reluctance motor are in the form of salient poles. There are no windings and permanent magnets on the rotor. The structure is simple and reliable, and the mechanical strength is high. However, only one of the two areas where the switched reluctance motor can be used to generate torque is used, and it is essentially a unilateral exciter. The winding current contains torque components and excitation components, which increases the volts of the winding and the power converter. Amp capacity, so efficiency and power density are lower. In the 1990s, American scholar Professor T.A. Lipo proposed a high-performance double-salient pole permanent magnet motor, which has the advantages of simple and reliable structure, maintenance-free, no winding on the rotor, and high efficiency. However, because the excitation magnetic field only uses permanent magnets, it is difficult to adjust the size of the air-gap magnetic field of the motor, so the motor's field-weakening speed regulation is very inconvenient, and it is difficult to be widely used in occasions that require stepless and frequent speed regulation. Although the speed regulation can be realized by changing the number of turns of the armature winding, it can only realize step-by-step speed regulation and cannot realize smooth stepless speed regulation.

Contents of the invention

Technical problem: The purpose of this invention is to provide a two-way hybrid excitation brushless motor with simple structure, reliable operation, maintenance-free, no winding on the rotor, and high efficiency, and at the same time solve the difficulty of smooth speed regulation of double salient pole permanent magnet motors The problem.

Technical solution: The stator yoke and the rotor yoke of the two-way hybrid excitation brushless motor of the present invention adopt a double yoke structure; the stator outer yoke and the rotor inner yoke used for axial magnetization are annular cylinders, and the stator outer yoke is covered by permanent magnets Divided into several equal parts, the length of the stator outer yoke and rotor inner yoke is the same as the length of the iron core laminated with silicon steel sheets; The outer yoke of the stator together constitutes the stator yoke part of the double yoke structure; the inner yoke of the rotor is tightly sleeved outside the rotating shaft, and the inner yoke of the rotor is surrounded by the outer yoke of the rotor, and the rotor teeth are arranged on the outer yoke of the rotor. Together constitute the rotor yoke of the double yoke structure. The inner side of the motor casing on both ends of the motor is provided with side magnetically conductive steel plates, and an axial air gap is left between the end of the side magnetically conductive steel plate near the axis and the inner yoke of the rotor, and the outer circle of the side magnetically conductive steel plate is close to The outer yoke of the stator is provided with pole shoes, the axial excitation coil is located on the outer edge of the side magnetically conductive steel plate, and the position sensor is located on the side magnetically conductive steel plate.

The motor adopts hybrid excitation combining permanent magnet and electric excitation. The main magnetic flux of the air gap is jointly generated by the permanent magnet and the axial excitation coil. The magnetic field of the permanent magnet is a radial magnetic field, and the electric excitation field is an axial magnetic field. When the motor is running under rated conditions, the excitation is provided by the permanent magnet. When the motor needs to run at a low-speed high-torque or high-speed constant power state, the field increase or field weakening control is realized by controlling the magnitude and direction of the axial excitation coil current. Magnetic control is beneficial to increase the torque of the motor to meet the requirements of low-speed and high-torque loads; magnetic field-weakening control can realize high-speed constant power and wide speed regulation of the motor. Both the stator and the rotor yoke adopt a double yoke structure. The stator outer yoke and the rotor inner yoke are mainly used for axial magnetic conduction to prevent the attenuation of the magnetic field strength when the axial magnetic field passes through the iron core laminations vertically: the stator inner yoke and the rotor outer yoke mainly Used for radial magnetic conduction. Since the axial electric excitation magnetic field does not pass through the permanent magnet with a large reluctance, the reluctance of the electric excitation magnetic field is small, which ensures that the required air gap magnetic field can be obtained without a large excitation magnetic potential, and the Demagnetization of permanent magnets can occur due to the application of an electrical excitation field.

Beneficial effects: the motor has a series of advantages such as simple and reliable double salient permanent magnet motor structure, maintenance-free, no winding on the rotor, high efficiency, etc. At the same time, certain improvements have been made to the structure and operating principle of the double salient permanent magnet motor , which effectively solves the problems that the doubly salient pole permanent magnet motor is difficult to realize field weakening control and the constant power speed regulation range is small. On the basis of retaining the double salient pole structure of the stator and rotor, the axial electric excitation magnetic field is introduced, which makes the adjustment of the combined air gap magnetic field convenient, so the motor has a wide range of stepless speed regulation, and it can be better even at high speeds. Achieving constant power speed regulation has good scientific research value and application prospect.

The motor adopts hybrid excitation combining permanent magnet and electric excitation. The main flux of the air gap is jointly generated by the permanent magnet and the axial excitation coil. The magnetic field of the permanent magnet is a radial magnetic field, and the DC excitation is an axial magnetic field. Both the stator winding and the excitation winding are installed on the stator, and their current can be controlled independently, which is convenient to adjust and flexible to control. When the motor is running under rated conditions, the excitation is provided by the permanent magnet. When the motor needs to run at a low-speed high-torque or high-speed constant power state, the field increase or field weakening control is realized by controlling the magnitude and direction of the axial excitation coil current. Magnetic control is beneficial to increase the torque of the motor to meet the requirements of low-speed and high-torque loads; magnetic field-weakening control can realize high-speed constant power and wide speed regulation of the motor. There are no coils and permanent magnets on the rotor, which can be used in high-speed applications.

The outer side of the motor end cover is made of aluminum alloy or other non-magnetic materials; the inner side is inlaid with axial excitation components processed by cast steel. The axial field poles are processed into pole shoes, so that there is enough space to install the field winding, which makes the structure of the motor more compact and reduces the amount of copper used.

Description of drawings

Fig. 1 is an axial sectional view of the motor of the present invention.

Fig. 2 is a schematic diagram of the cross-sectional structure of the motor of the present invention.

Fig. 3 is a structural diagram of the magnetically permeable and magnetically permeable plate on the side of the motor of the present invention.

Among them, there are axial excitation coil 1, radial air gap 2, axial air gap 3, motor casing 4, side magnetic steel plate 5, magnetic pole shoe 6, position sensor 7, rotating shaft 8, stator outer yoke 9, stator inner yoke 10. Stator teeth 11, stator windings 12, rotor teeth 13, rotor outer yoke 14, rotor inner yoke 15, permanent magnet 16.

The above figure is an example of a motor with 12 teeth on the stator and 8 teeth on the rotor (referred to as 12/8 poles). According to the operating principle of the motor, it is also applicable to motors with 6/4 poles, 8/6 poles or other poles. Two-way hybrid excitation brushless motor.

Detailed ways

1. The basic structure of the two-way hybrid excitation brushless motor is the same as other rotating motors (as shown in Figure 1). There is a fixed part of the stator and a rotating part of the rotor. There is a small radial air gap between the stator and the rotor. The stator is composed of stator winding 12, stator core (including silicon steel sheet lamination part and electrical pure iron part), permanent magnet 16, position sensor 7, excitation pole shoe 6, excitation winding 1, and side magnetic conductive steel plate 5. Among them, stator teeth 11 and slots are punched on the inner circle of the iron core of the laminated part of the silicon steel sheet, and the pole arc of the teeth is 1/2 of the tooth pitch, and the winding in the slot is made of insulated copper wire; A rotor position sensor 7 is fixed and consists of a Hall sensor. The rotor is composed of a rotor core (containing silicon steel laminated parts and electrical pure iron parts) and a rotating shaft 8, wherein rotor teeth 13 and grooves are punched on the outer circle of the silicon steel laminated part of the iron core to form salient poles.

2. Because the magnetic field intensity is greatly attenuated when the axial magnetic field passes through the iron core laminations vertically, the stator and rotor yokes adopt a double yoke structure. The stator outer yoke 9 and the rotor inner yoke 15 are mainly used for axial magnetic conduction. The electric pure iron is used to process the annular cylinder (the outer yoke of the stator is divided into several equal parts by the permanent magnet, as shown in Figure 2), and the length of the cylinder is the same as that of the iron core. The rotor inner yoke 15 is tightly fitted on the rotating shaft 8 , and its outer surface is a rotor core lamination including the rotor outer yoke 14 and the rotor teeth 13 . The stator outer yoke 9 is inside the motor casing 4 , and the stator inner yoke 10 is made of laminated silicon steel sheets with a thickness of 0.5 mm, which is close to the stator outer yoke 9 and forms the stator yoke together with the stator outer yoke.

3. The outer side of the motor end cover is made of aluminum alloy or other non-magnetic materials; the inner side is inlaid with axial excitation components, which are processed from cast steel and serve as a part of the axial magnetic circuit. The magnetic pole piece 6 on the stator side is in close contact with the stator outer yoke 9 in the axial direction, and the axial air gap between the magnetically conductive magnetic pole on the rotor side and the rotor inner yoke is preferably small to reduce the reluctance of the axial magnetic circuit. In order to reduce the manufacturing cost of the motor and make the structure more compact, the axial excitation poles are processed into the form of pole shoes, which can ensure enough space to install the excitation winding, reduce the amount of copper used, and improve the operating efficiency of the motor. In order to ensure the uniform distribution of the axial magnetic field in the stator and rotor core laminations, the axial dimension of the motor should not be too long, and both sides of the motor need to be axially excited, and the number of axial excitation coils 1 on each side is the same as that of permanent magnets Number, there should be enough distance between the outer edge of the pole piece 6 and the permanent magnet 16 to prevent magnetic flux leakage.

4. The permanent magnet (NdFeB permanent magnet material) 16 and the stator winding 12 are installed on the stator, the excitation winding 1 is installed on the excitation pole, and there is no winding and no permanent magnet on the rotor. The motor structure is simple and reliable, so that the motor can run without brush and high speed operation. The permanent magnets 16 are evenly installed on the stator yoke, and the N-N poles of the permanent magnets face each other, and the S-S poles face each other (as shown in Figure 2), so that a magnetic concentration effect is generated at the air gap magnetic field; each stator tooth 11 is equipped with a stator The winding 12, the stator winding adopts concentrated winding, and the two coils corresponding to the spatial positions are connected in series or in parallel according to the principle of potential addition or the same direction to form a phase of the armature winding.

5. The path of the main magnetic flux:

The order of the radial main magnetic flux path is: permanent magnet N pole; stator yoke; stator teeth; radial air gap; rotor teeth; rotor yoke; rotor teeth; radial air gap; stator teeth; stator yoke; permanent Magnet S pole;

The order of the axial main magnetic flux path is: N pole of electric excitation pole (or S pole, depending on the direction of excitation current, the same below); excitation pole pole shoe; stator outer yoke; stator inner yoke; stator teeth; radial air gap ;Rotor teeth; rotor outer yoke; rotor inner yoke; axial air gap; magnetic pole; side magnetic steel plate; electric excitation pole S pole (or N pole).

Claims (2)

1. A two-way hybrid excitation brushless motor is characterized in that the stator yoke and the rotor yoke of the brushless motor adopt a double yoke structure; the stator outer yoke (9) and the rotor inner yoke (15) for axial magnetization ) is an annular cylinder, wherein the stator outer yoke (9) is divided into four equal parts along the circumferential direction by permanent magnets (16), and a permanent magnet (16) is arranged between each two parts, and the magnetic poles of the permanent magnets are arranged along the circumferential direction , the permanent magnets (16) are evenly installed on the stator yoke, and the N-N poles of the permanent magnets face each other, or the S-S poles face each other, and the axial lengths of the stator outer yoke (9) and the rotor inner yoke (15) are laminated with silicon steel sheets The stator inner yoke (10) and the rotor outer yoke (14) have the same axial length; the stator outer yoke (9) is on the inner side of the motor casing (4), and the stator inner yoke (10) is located on the inner side of the stator outer yoke (9) , the stator inner yoke (10) and the stator outer yoke (9) together constitute the stator yoke part of the double yoke structure; The yoke (14) is provided with rotor teeth (13) on the rotor outer yoke (14), and the rotor yoke part of the double yoke structure is jointly formed by the rotor inner yoke (15) and the rotor outer yoke (14); the stator winding (12) Installed on the stator, each stator tooth (11) on the stator inner yoke (10) is covered with a stator winding (12), thereby matching with the rotor structure to realize the operation of the motor, and the rotor has no winding. 2. The two-way hybrid excitation brushless motor according to claim 1, characterized in that a side magnetically conductive steel plate (5) is provided on the inner side of the motor casing (4) on both ends of the motor, and the side magnetically conductive steel plate (5) ) has an axial air gap (3) between the part close to the shaft center and the rotor inner yoke (15), and a magnetic pole is provided on the outer circle of the side magnetic conductive steel plate (5) close to the stator outer yoke (9). shoe (6), the axial field winding (1) is wound on the magnetic pole shoe (6), the axial field winding (1) is located on the outer edge of the side magnetic conductive steel plate (5), and the rotor position sensor (7) is located on the side On the magnetic steel plate (5).

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