RU2810539C1 - Electric motor with axial magnetic flux - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: brushless electric DC motor with permanent magnets with an axial magnetic flux contains a rotor consisting of a shaft with several washer-shaped rings strung and fixed on it at a certain distance from each other. On the flat surface of the rings there are recesses or cutouts multiplied around the circumference at equal distances from each other in accordance with the number, size and shape of the permanent magnets placed in them. The stator has a prefabricated modular design and is a ring of similar windings placed around the circumference with cores in the form of branched magnetic circuits having several magnetic circuits arranged in a row with air gaps. The number of magnetic circuits and the size of the air gaps of each core correspond to the number and thickness of the rotor rings. The cores, with their long straight part, are oriented parallel to the axis of rotation of the shaft and face their gaps in the radial direction towards the motor shaft in such a way that the gaps of the magnetic circuits form parallel circular through air slots according to the number of magnetic circuits, within which the rotor rings are located and rotate.

EFFECT: increase in traction torque and motor efficiency.

5 cl, 11 dwg

Description

The invention relates to the electrical engineering field, in particular to brushless DC electric motors with permanent magnets and can be used in electric drives of general industrial mechanisms and vehicles, namely, in electric-powered aircraft, scooters, motorcycles, and cars. The technical result is an increase in the traction torque of the electric motor and an increase in the efficiency of the motor.

The technical result of the proposed electric motor is achieved by the design feature of the motor with an axial magnetic flux topology, in which the interaction of magnetic fluxes generated by the stator windings and permanent magnets of the rotor is carried out in the most efficient manner.

A brushless rotary electric motor is known from the prior art (RF patent No. 2528983, H02K 31/00, publication date 09.20.2014), containing a stator with a winding and a rotor rotating on bearings, characterized in that the stator is made in the form of a toroid with an external winding of the coil , and the rotor, rotating inside the stator on bearings, has permanent magnets in the form of cylinders located tangential to the rotor. The disadvantage of the engine is its complex design, low power torque and engine efficiency.

Over the past decade, a variety of electric motors with an axial magnetic flux topology has been gaining momentum. These motors have higher power and torque density than comparable sized traditional radial flux motors. There are two main topologies of axial flux motors: the double-rotor single stator, sometimes called a torus-type machine, and the single-rotor dual-stator.

The prototype of the claimed invention can serve as an anchor-free electric motor from the Belgian company MAGNAX (https://zen.yandex.ru/media/htech_plus/magnax-kak-rabotaet-sverhmoscnyi-elektromotor-buduscego-5d93482b4e057700b117fa81), made according to the topology with an axial magnetic flux with two rotors and one stator (Fig. 1). It consists of a rotor, which consists of two disks with permanent magnets placed on them around the circumference with the axial direction of the magnetic flux. The spacer between two rotor disks houses a stationary stator with windings, the straight cores of which are arranged in a circle parallel to the axis of rotation of the shaft. The motor rotor rotates due to the interaction of magnets, which repel and attract each other when a magnetic field occurs. Currently, the MAGNAX motor is considered one of the most efficient motors in its category. However, despite this, MAGNAX has the following disadvantages:

1. Insufficiently effective interaction of the magnetic fluxes of the stator and rotor.

2. high cost due to double the number of expensive permanent magnets placed on two rotor disks

3. Low level of torque and motor power

The claimed electric motor is devoid of the above disadvantages. The technical result of the proposed electric motor is achieved by using non-standard solutions in the motor regarding the design of the rotor and stator, which contribute to the most efficient interaction of the magnetic fluxes of the stator and rotor and increase the torque and power of the motor. The inventive motor belongs to the topology with an axial magnetic flux in a conventionally multi-rotor and multi-stator design.

The claimed electric motor is illustrated by the drawings shown in Fig. 1-11.

Fig. 1 - anchorless electric motor from MAGNAX.

Fig. 2 - simplified diagram of the motor design

Fig. 3 - simplified rotor design

Fig. 4 - example of a prefabricated rotor structure

Fig. 5 - stator link core without winding

Fig. 6 - stator link core with winding

Fig. 7 - stator of modular design

Fig. 8 - the claimed motor assembled

Fig. 9 - the claimed motor with a truncated number of links

Fig. 10 - general view of the waterproof motor

Fig. 11 - diagram of the interaction of magnetic fluxes.

The inventive electric motor is characterized by the fact that it is a brushless electric DC motor with permanent magnets with an axial magnetic flux directed parallel to the longitudinal axis of the motor. The design of a motor with an internal rotor is shown in a simplified form in Fig. 2.

The figure shows that the motor rotor consists of a shaft 1 with several washer-shaped rings 2 strung and fixed on it at a certain distance from each other. On the flat surface of the rotor rings 2 there are recesses or cutouts multiplied around the circumference at an equal distance from each other in accordance with the number, size and shape of permanent magnets 4 placed in them. In the figure, the rotor has three rings 2 with disk-shaped permanent magnets 4 fixed on their flat surface. Structurally, the motor can be designed with an arbitrary number of rotor rings from one to several, depending on the required characteristics of power, torque and rotation speed.

Fig. 3 shows in simplified form two types of rotor design depending on the type of motor. Option a) is a rotor that assumes internal placement (inrunner) in an electric motor, option b) is an external placement (outrunner). As can be seen from the figure for the inrunner motor, the rotor rings 2 are strung and secured to the motor shaft 1 at a certain distance from each other. For an outrunner motor, shaft 1 has the shape of a hollow cylinder and rotor rings 2 are placed and fixed in the internal cavity of the shaft. The number of rotor rings 2 can be arbitrary from one to several. The more rings, the higher the motor power and torque.

As noted earlier, on the flat surface of the rotor rings 2 there are recesses or cutouts multiplied around the circumference at an equal distance from each other in accordance with the number, size and shape of the permanent magnets 4 placed in them. In the case under consideration, the permanent magnets 4 used have the shape of a sector or disk . Magnets on the rotor rings generate an axial magnetic flux parallel to the axis of rotation of motor shaft 1.

In both cases, the motor rotors can have either a monolithic or a prefabricated structure, consisting separately of a motor shaft 1 and rotor rings 2. For a better understanding, FIG. Figure 4 shows one of the possible options for a prefabricated rotor design with internal placement. For ease of perception, the figure shows only two rotor disks 2, each of which is a prefabricated structure of two halves, conventionally left and right. For clarity, each rotor disk shows only two permanent magnets 4 in the shape of a sector. At the junction of the magnet faces there are small bevels in the form of chamfers. Each half of the rotor disk 2 has two holes that exactly match the shape, size and chamfers of the permanent magnets 4 placed in them. When the left and right halves of the rotor disk are tightly adjacent to each other, reliable fixation of the magnet 4 in the hole of the composite rotor disk 2 is ensured. Separating sleeves 6 are designed to ensure a tight fit of the rotor halves to each other and fixation of the composite rotor rings 2 at a certain distance from each other. For simplicity, the figure does not show the method of fixing the bushings 6 and rotor rings 2 on the motor shaft 1 to prevent both their rotation around their axis and the shift of the entire assembly structure along the axis of shaft 1.

The stator (Fig. 1) has a prefabricated modular design and is a ring of similar links placed around the circumference. Each link consists of windings 3 with cores 5 in the form of branched magnetic circuits having several magnetic circuits arranged in a row with air gaps. The number of magnetic circuits and the size of the air gaps of each core correspond to the number and thickness of the motor rotor rings. The cores 5 with their long rectilinear part are oriented parallel to the axis of rotation of the shaft, and with their gaps facing in the radial direction to the motor shaft so that the air gaps of all magnetic cores 5 assembled in a circle form parallel circular through air slots according to the number of magnetic circuits within which they are located and rotate rotor rings 2. For clarity, in Fig. 1 motor stator contains only three links of the same type, distributed around the circumference at an equal distance from each other. The core of each link has three magnetic circuits with air gaps according to the number of rotor rings.

In fig. Figure 5 shows a general view of the stator link without winding. In the case under consideration, the stator link is made in the form of a core 5, which is a branched magnetic circuit having three magnetic circuits. For clarity, in the figure one of the magnetic circuits 7 is conventionally highlighted with a red dotted line. Each magnetic circuit 7 has an air gap 8. The number of magnetic circuits 7 and the width of the air gaps 8 of each core 5 correspond to the number and thickness of the rotor rings 2 at the attachment point of the permanent magnets 4. In addition, the cross-section of the teeth 9 of the core 5 must correspond in shape and size to the shape and the dimensions of the permanent magnets 4 used. In the case under consideration in FIG. Figure 5 shows examples of two cores 5 having a cross-section in the shape of a circle and a sector, respectively.

In fig. Figure 6 shows an example of a stator link with a winding. As can be seen from the figure, the stator link winding does not have a solid multi-link structure, but is assembled according to a modular principle from individual coils of the same type 10 with a frame, each of which is strung and fixed on a tooth 9 of the core 5, followed by connecting the ends of the coil windings into a single link winding. The shape of the coil frame 10 must correspond to the cross-section of the tooth 9 of the core. In the case under consideration, the coil has a cylindrical shape. The length of the coil frame should not exceed the size of the air gap 8 of the core.

The proposed modular design of the stator link winding significantly simplifies the technological process of manufacturing the motor stator as a whole. A side effect of the winding modularity is the ability to easily restore the motor to an operational state after failure or damage. As a rule, the main cause of motor malfunction is winding damage. In a modular design, restoration of the motor's performance is accomplished by simply replacing a damaged coil without the need to rewind the entire winding.

As noted above, the main distinguishing feature of the motor stator is its modular design, consisting of similar units. The cores of the links in cross section have the shape of a sector, which allows them, when assembled together in a circle, tightly adjacent to each other, to form a single cylindrical structure of the prefabricated stator, shown in Fig. 7.

As can be seen from the figure, the stator has a prefabricated structure of a cylindrical shape, assembled from the same type of links 11, having the shape of a cylinder segment. Each link 11 is a multi-circuit branched core with windings of coils 10 (Fig. 6), generating an axial magnetic flux directed parallel to the axis of rotation of the motor shaft. The figure shows that the air gaps of the cores, assembled in a circle into a single structure, create circular through air gaps according to the number of magnetic circuits, inside which the rotor rings are located and rotate.

In fig. Section 8 a) presents a general view of the proposed motor with the internal arrangement of the assembled rotor in two projections. The stator has a prefabricated structure of the same type of links 11, having the shape of a cylindrical sector. For clarity, section b) shows a longitudinal section of the motor.

The stator core 5 has five magnetic circuits with air gaps. The rotor has five rings 2 according to the number of magnetic circuits with permanent magnets 4 fixed on their flat surface. The stator windings 10 create a magnetic flux parallel to the axis of rotation of the motor shaft. The motor shaft 1 has a hollow structure.

A motor design option is possible in which, out of the total number of similar motor stator links, only a portion of the links can be used, combined into two groups with the same number of links, and the groups themselves are placed opposite each other symmetrically relative to the longitudinal axis of the motor (Fig. 9).

The described design helps reduce the size and weight of the motor, and also simplifies the technological process of manufacturing and assembling the motor.

The version of the motor with an internal rotor and a hollow shaft makes it possible to place a blade mechanism inside the shaft, in particular, in the form of a replaceable block, which is a structure of an annular tubular channel in the form of a hollow cylinder with a multi-bladed screw or auger spiral placed and secured inside it. In this case, the replaceable unit may have a monolithic design or consist of separate modules, which may differ from each other in their design features and purpose. To ensure the possibility of functioning in water, the motor can be structurally made in a waterproof design, in which the replaceable unit is used as a water-jet propulsion unit (Fig. 9). The figure shows a waterproof version of the proposed electric motor in a simplified form.

For clarity, a waterproof electric motor is presented consisting of the following main blocks:

• Motor body 12, the main components of which are a stator, a rotor and a hollow shaft, inside of which the water-jet propulsion device 15 is located

• water intake part 13 - the front area that facilitates the movement of water (incoming flow) to the screw part of the water-jet propulsion unit 15.

• water-jet propulsion unit 15, made in the form of a replaceable block, which is a structure made of an annular tubular channel in the form of a hollow cylinder with a blade mechanism placed and fixed inside it in the form of a multi-bladed screw or auger spiral, and the block itself can have a monolithic design or be assembled sequentially in a single design of individual modules, which do not necessarily have to be of the same type and may differ from each other in their design features. In the variant under consideration, the replaceable unit is made in the form of a screw spiral in a monolithic design.

• Nozzle 14 with a straightening hardware element that transforms the rotational movements of water flows into rectilinear ones (outgoing flow).

The waterproof version of the proposed motor can be used in shipbuilding as power plants. The use of electric motors does not harm the environment and sometimes significantly reduces the cost of operating electric-powered ships.

As noted earlier in the inventive motor, due to the design features of the stator and rotor, the intensity and efficiency of the interaction of the magnetic fields of the stator and rotor of the motor is significantly higher compared to currently existing solutions in this area.

In fig. Figure 10 shows a diagram of the interaction of the magnetic fields of the stator and rotor of the motor in relation to three options for constructing brushless DC electric motors with permanent magnets:

a) classic brushless motor

b) electric motor from MAGNAX

c) the claimed electric motor in terms of axial topology

The motor rotor rotates due to the interaction of the magnetic fields of the stator and rotor, which repel and attract each other when a magnetic field occurs. For simplicity, the presented diagram illustrates only the attraction of magnets. Thin lines with arrows show the intensity and direction of the magnetic flux generated by the stator winding 3 and the permanent magnet 4 of the rotor.

In a classic brushless motor, the cores 5 of the windings 3 are conventionally rectilinear magnetic circuits located in the radial direction from the axis of rotation of the motor shaft. In fig. 10 in section a) illustrates the interaction diagram of the magnetic field of a rectilinear core 5 with the magnetic field of a permanent magnet 4. As can be seen from the figure, with such an arrangement of the core and permanent magnet 4, there is a one-way interaction between the magnetic fluxes emanating from one end of the core 5 and from one axial sides of the magnet 4. In this case, the loss of magnetic induction is significant.

The MAGNAX electric motor takes into account the disadvantages of the classic brushless motor. Here, the windings 3 also use rectilinear cores 5, which are located in a circle parallel to the axis of rotation of the shaft. The cores are placed between two rotor disks with permanent magnets 4 located on them along the circumference. As can be seen in Fig. 10 in section b) the magnetic field of the core 5 interacts with permanent magnets 4 simultaneously from both ends. However, the resulting magnetic flux is not closed in nature and magnetic flux dissipation also occurs.

The inventive electric motor eliminates the disadvantages inherent in the types of electric motor discussed above. The stator winding has a core 5 in the form of a branched magnetic circuit having several magnetic circuits with air gaps 8, slightly exceeding the thickness of the magnet. In fig. 10 in section c) illustrates a diagram of the interaction of the magnetic fields of a branched core 5, which has three circuits, with the magnetic fields of permanent magnets 4. The cross-section of the core 5 must correspond to the shape and size of the magnet 4. When current passes through the winding, a magnetic field is generated, many times amplified by the core. The direction of the magnetic flux changes depending on the direction of the current in the winding. At the air gap 8 of the core 5 there is a slight dissipation of the magnetic flux. In the figure, the lines also show the intensity and direction of the magnetic flux created by permanent magnets 4. As you can see, a permanent magnet has an axial direction of the magnetic field. When the permanent magnet 4 passes through the air gap 8 of the core 5, the magnetic flux is closed. In this case, the strength of the magnetic flux in the core circuit increases many times. With the described arrangement of the rotor magnets and the stator core, the attractive force acts simultaneously on the two axial sides of the magnet, while losses of magnetic induction are minimal. The force of interaction of magnetic fluxes is proportional to the number of magnetic circuits of the core.

The technical result of the magnetic interaction described above is an increase in the traction torque of the proposed motor and an increase in its efficiency.

Claims (5)

1. An electric motor with an axial magnetic flux, characterized by the fact that it is a brushless DC electric motor with permanent magnets, the rotor of which is a monolithic or prefabricated structure consisting of a shaft with several washer-shaped rings strung and fixed on it at a certain distance from each other in such a way that the axes of the rings coincide with the longitudinal axis of the motor shaft, and on the flat surface of the rings there are recesses or cutouts multiplied around the circumference at an equal distance from each other in accordance with the number, size and shape of the permanent magnets placed in them, and the stator has a prefabricated modular design and is a ring of similar links placed around the circumference, which are windings with cores in the form of branched magnetic circuits, having several magnetic circuits arranged in a row with air gaps, and the number of magnetic circuits and the size of the air gaps of each core correspond to the number and thickness of the rotor rings, in this case, the winding cores with their long straight part are oriented parallel to the axis of rotation of the shaft, and with their air gaps facing in the radial direction to the longitudinal axis of the motor so that the air gaps of all magnetic circuits assembled in a circle form parallel circular through air gaps according to the number of magnetic circuits, inside which The rotor rings are positioned and rotated. 2. The electric motor according to claim 1, characterized in that the design of the motor with an external rotor arrangement is structurally acceptable, characterized in that the motor rotor is a structure made of a hollow shaft, inside of which several washer-shaped rings are placed and fixed at a certain distance from each other in such a way that the axes of the rings coincide with the longitudinal axis of the motor shaft, and the stator cores in this case, with their air gaps, face in the radial direction from the longitudinal axis of the motor so that the air gaps of all cores assembled in a circle form parallel circular through air gaps, inside which are located and the rotor rings rotate. 3. The electric motor according to claim 1, characterized in that the winding of the stator link is assembled according to a modular principle from separate coils of the same type, each of which is strung and fixed on a tooth of the core, followed by connecting the ends of the windings of the coils into a single core winding. 4. The electric motor according to claim 1, characterized in that it is possible to have a motor with a hollow shaft, inside which a replaceable unit is placed and fixed, which is a structure of an annular tubular channel in the form of a hollow cylinder with a screw spiral or a multi-blade screw placed and fixed inside it, Moreover, the block itself has a monolithic design or is assembled into a single structure from separate modules. 5. The electric motor according to claim 4, characterized by the fact that in the design of the motor, designed in a waterproof version, the replaceable unit is used as a water-jet propulsion device.