RU126996U1 - Brushless DC Motor - Google Patents

Abstract

1. Brushless DC motor, including: an internal rotor containing individual permanent magnets uniformly spaced around a circle with an alternating direction of the magnetic field; an external stator containing two identical groups of electromagnets located circumferentially on different sides of the rotor opposite each other so that the axis of the electromagnet coils are parallel to the axis of rotation; rotor position sensors; an electromagnet control unit, characterized in that the number of phases N of the electric motor can be any number from a number N = 2, 3, 4, 6; the number m of electromagnets in each group is a multiple of the number of phases; the number n of poles of permanent magnets on one side of the rotor is even, not a multiple of the number of phases, greater than the number m of electromagnets in the group and not a multiple of their number; the number L of rotor position sensors is not less than the number of phases. 2. The electric motor according to claim 1, characterized in that the electromagnets have horseshoe-shaped cores and n> 2m. 3. The electric motor according to claim 1, characterized in that the number of phases N is odd and the number of rotor position sensors is N + 1.4. The electric motor according to claim 1, characterized in that the number of phases N is even and the number of rotor position sensors is N.5. The electric motor according to claim 1, characterized in that each of the electromagnets has an independent connection to the control unit. The electric motor according to claim 2, characterized in that the angular distance between the centers of the teeth of the electromagnet is equal to the angular distance between the centers of adjacent magnetic poles on one side of the rotor. The electric motor according to claim 2, characterized in that the electromagnet coils have the opposite direction

Description

The utility model relates to the field of DC motors, in particular gearless brushless low-voltage electric motors for vehicles: electric scooters, motorcycles, electric vehicles, etc., and can also be used in other areas of technology.

The most promising for individual electric vehicles are gearless motor wheels, in which the rotation of the wheel is caused directly by the electromagnetic interaction of the magnetic systems of the rotor and stator. Such engines are environmentally friendly, compact, economical, simple and easy to operate.

Two constructive approaches to creating motor wheels are known: these are collector electric motors in which permanent magnets are located on the stator, and electromagnets and sliding current collectors are mounted on the rotor, which provide electrical contact with the plates of the electric collector (US 6384496 B1, 05/07/2002; US 6617746 B1 09.09.2003; RU 2129965 C1, 05/10/1999; RU 2172261 C1, 08.20.2001); and brushless motors containing an external rotor with permanent magnets and a stator with electromagnets powered from the control unit by a signal from the rotor position sensors (RU 2091969 C1, 09.27.1997; US 6727668 B1, 04/27/2004; US 6762525 B1, 07/13/2004; US 6791226, 09/14/2004; US 6853107 B2, 02/08/2005; RU 2265271 C1, 11/27/2005; RU 2343620 C2, 01/10/2009).

Brushless motors in a number of applications have advantages over brush motors, due to the absence of slip of conductive elements and greater control flexibility.

Such engines have already found their application, but there are a number of areas in which it is possible to improve their operational characteristics. Traditionally, high-torque, low-speed motor-wheel motors have lower efficiency than high-speed electric drives. This is due to an increase in the total resistance due to an increase in the number of turns on the windings. At the same time, heat generation increases and the task of cooling the electric motor arises.

Another problem in the operation of gearless electric motors in vehicles is the presence of "dead zones" and the non-optimality of their work in a wide dynamic range, especially in start / stop modes. A partial solution to this problem will be the use of several electric motors on one vehicle, each of which is optimized for its dynamic range. For example, in patent RU 2290328 dated December 27, 2006, an all-wheel drive vehicle with an accelerating and marching engine of the motor-wheel type is described. But such a solution also complicates the design and has limited application.

They are trying to solve the increase in efficiency and increase in torque under various operating conditions by optimizing the control system (US 6727668 B1, 04/27/2004; US 6791226, 09/14/2004) and enhancing the magnetic flux, by choosing the number and location of magnets and electromagnets, as well as manufacturing cores of a special form (US 6762525 B1, 07/13/2004). All this leads to a complication of production and does not solve the final task: the creation of a universal efficient engine for various vehicles.

This utility model is aimed at creating a low-speed gearless electric motor, with a high torque, having a universal, relatively simple design, and suitable for use in various operating conditions.

Compared with the classic electric drive circuit, using a high-speed electric motor and gearbox, the present utility model can significantly improve the economy and mass-dimensional performance of the drive, and reduce the noise level of its operation. At the same time, the efficiency and heat loss are maintained at the level of classic high-speed electric motors.

The technical result from the use of this utility model is the simultaneous reduction of heat loss; improving the dynamic characteristics of the electric motor in start-stop modes; increase in torque; cheaper production.

The claimed technical result is achieved by the fact that the brushless DC motor includes an internal rotor containing individual permanent magnets evenly spaced around the circle with the alternating direction of the magnetic field; an external stator containing two identical groups of electromagnets located circumferentially on different sides of the rotor opposite each other so that the axis of the electromagnet coils are parallel to the axis of rotation; rotor position sensors; control unit for electromagnets. The number of permanent magnets and electromagnets, their relative position is selected in such a way as to ensure maximum closure of the magnetic field within each phase. The number of phases N of the electric motor can be any number from the series N = 2, 3, 4, 6. The number m of electromagnets in each group is a multiple of the number of phases. Permanent magnets are arranged so that their poles extend to both sides of the rotor located between the groups of stator electromagnets. The number n of poles of permanent magnets on one side of the rotor is even, not a multiple of the number of phases, greater than the number m of electromagnets in the group and not a multiple of their number. The number L of rotor position sensors is not less than the number of phases.

Electromagnets usually have horseshoe-shaped cores with two coils. In this case, n> 2m. The electromagnet coils have the opposite winding direction. Electromagnets located opposite each other form a pair. In a pair of electromagnets, coils located on the teeth, which are located opposite each other, have the same direction of the winding.

The rotor is usually made of non-magnetic material. This allows you to most effectively close the field between pairs of electromagnets and to avoid scattering of the magnetic field between adjacent electromagnets in the group. The angular distance between the centers of the teeth of the electromagnet is chosen equal to the angular distance between the centers of adjacent magnetic poles on one side of the rotor.

The number of rotor position sensors is always no less than the number of phases. Preferably, in the case of an even number of phases N, the number of rotor position sensors is also equal to N. In the case of an odd number of phases N, the number of rotor position sensors will be N + 1. This design allows you to avoid "dead zones" and jerking when starting.

Each of the electromagnets can have an independent connection to the control unit. But usually the electromagnets in a pair are connected in a single circuit and the pair is already connected to the control unit. The connection is carried out during the assembly of the engine. In this case, the electromagnets in pair can be connected in series or in parallel, depending on the purpose of the engine. To increase the torque of the electric motor, use a serial connection, to increase the speed of rotation - parallel.

In the case of the number of electromagnets greater than twice the number of phases, their pairs are combined into phase groups. The number of such groups is equal to the number of phases, and the number of electromagnets in each phase group is the same. A single control signal is applied to each group. Within a group, electromagnets can be connected in series or in parallel. The switching of electromagnets is carried out by the control unit, and it can also occur in dynamic mode. The control unit provides a sinusoidal control signal to the electromagnets, the phase displacement of which can be dynamically changed in the range from - 60 to 0 phase degrees.

To implement the recovery mode, the windings of a pair of electromagnets are included in the power circuit through a diode bridge. Moreover, all pairs of electromagnets in the phase group are connected in series. For the efficiency of the recovery process, it is preferable that the diode bridge contains diodes with a speed of 40 to 200 ns.

An inductive step-up DC-DC converter can also be used to implement the recovery mode. It is usually installed between the positive output of the circuit and the positive contact of the battery. Structurally, such a converter can be included in the control unit.

Depending on the purpose of this electric motor, different schemes for installing the electrical part of the engine in the housing are used. For a number of applications (electric bicycles, scooters, electric cars and other vehicles), it is preferable to install the stator on a fixed axis and connect the rotor to the movable rim of the wheel, ensuring its direct rotation. For other applications (electric lifts, the main rotor of an airplane or helicopter, propellers, etc.), it is preferable to provide rotation of the motor shaft with the housing stationary. In both cases, they use similar designs of the electrical part of the engine and its control circuit.

On light vehicles (scooter, electric car), three-phase electric motors are usually used. At the same time they will contain 18 electromagnets (9 pairs) and 24 permanent magnets (24 magnetic poles on each side of the rotor). For vehicles of other purposes (bus, tractor, etc.), motors with a large number of phases can be used. So, for example, a 4-phase electric motor can contain 12 pairs of electromagnets, and permanent magnets, the number of which is selected from a number of numbers m = 26, 30, 34.

The essence of this utility model is illustrated by the following drawings:

Figure 1 presents a diagram of the inventive electric motor;

Figure 2 shows an electric motor element comprising a pair of electromagnets;

Figure 3 presents a diagram of a three-phase electric motor with a series connection of electromagnets in pair;

Figure 4 presents a diagram of a three-phase electric motor with a parallel connection of electromagnets in pair;

5 (a) and (b) are a diagram of control signals for a 3-phase electric motor;

Figure 6 presents the electrical circuit of the phase switching according to the type of "triangle" and "star" for a 3-phase electric motor;

7 shows a diagram of energy recovery for a 3-phase electric motor;

On Fig shows a diagram of energy recovery with an inductive step-up DC-DC converter;

Figure 9 (a) presents a diagram of the present electric motor, made in the embodiment of the motor-wheel;

Figure 9 (b) presents a diagram of a real electric motor with a rotating shaft. Figure 10 (a, b) presents the dependence of the dynamic characteristics of the electric motor.

одной группы располагался точно напротив электромагнита

другой группы с воздушным промежутком между сердечниками; электромагнит

напротив электромагнита

и т.д (Фиг.1, 2). Постоянные магниты ротора движутся в воздушном зазоре, образованном двумя группами электромагнитов статора. Оси катушек 5 электромагнитов параллельны оси вращения электродвигателя (на Фиг.1 эта ось изображена нормально к плоскости рисунка). Обычно электромагниты 4 имеют подковообразные сердечники с двумя катушками 5. Соотношение между размерами элементов электродвигателя подбирают таким образом, чтобы угловое расстояние а между центрами зубцов электромагнита 4 было равно угловому расстоянию β между центрами соседних магнитных полюсов 2 с одной стороны ротора. На статоре также расположены датчики 6 положения (ДП) ротора.The inventive electric motor (Figure 1) includes an internal rotor 1 with permanent magnets 2, evenly spaced around a circle with an alternating direction of the magnetic field. The rotor is usually made of non-magnetic material. The external stator contains two identical groups of 3 'and 3 "electromagnets 4 located around the circumference. Both parts of the stator are installed so that the electromagnet

one group was located exactly opposite the electromagnet

another group with an air gap between the cores; electromagnet

opposite the electromagnet

etc (Fig.1, 2). Permanent rotor magnets move in the air gap formed by two groups of stator electromagnets. The axis of the coils 5 of the electromagnets are parallel to the axis of rotation of the electric motor (in Figure 1, this axis is shown normally to the plane of the figure). Typically, electromagnets 4 have horseshoe-shaped cores with two coils 5. The ratio between the sizes of the electric motor elements is selected so that the angular distance a between the centers of the teeth of electromagnet 4 is equal to the angular distance β between the centers of adjacent magnetic poles 2 on one side of the rotor. On the stator are also located sensors 6 position (DP) of the rotor.

The number of phases N of the electric motor can be any number from the series N = 2, 3, 4, 6. Figure 1 shows a 6-phase electric motor. The number m of electromagnets 4 in each group is a multiple of the number of phases, and in this case also 6. The total number of electromagnets in the electric motor is 12. The number n of poles of permanent magnets 2 on one side of the rotor is even, not a multiple of the number of phases, greater than the number m of electromagnets in the group and not a multiple of their number. In this case, it is equal to 20 pcs. The number L of sensors 6 of the rotor position is not less than the number of phases. If the number of phases N is odd, then the number of rotor position sensors 6 is N + 1. If the number of phases N is even, then the number of rotor position sensors 6 is N. In this case, their number is 6 pcs.

с

;

с

и т.д.) и уже эти пары подключаются к БУ. К нему также подключены датчики 6 положения ротора. БУ может быть расположен как внутри, так и снаружи электродвигателя.Each of the electromagnets 4 can be independently connected to a control unit (CU) (not shown in the figure), but usually electromagnets from different groups located opposite each other are connected in pairs (

from

;

from

etc.) and already these pairs are connected to the control unit. Sensors 6 of the rotor position are also connected to it. The control unit can be located both inside and outside the electric motor.

и

,

и

, и т.д. располагаются таким образом, что катушки, размещенные на зубцах, расположенных напротив друг друга имеют одинаковое направление обмотки. Такая конструкция позволяет наиболее полно замкнуть магнитное поле между парами электромагнитов. Кроме того изготовление ротора из немагнитопроводного материала позволяет избегать рассеяния поля между соседними электромагнитами в группе.The coils of each of the electromagnets have the opposite direction of the winding (Figure 2). Moreover, each pair of electromagnets

and

,

and

, etc. arranged so that the coils placed on the teeth located opposite each other have the same direction of the winding. This design allows you to most fully close the magnetic field between the pairs of electromagnets. In addition, the manufacture of the rotor from a non-magnetic material allows to avoid field scattering between adjacent electromagnets in the group.

It is known that the magnitude of the motor torque linearly depends on the total number of turns of each phase of the motor and the magnetic flux closed through the cores of the electromagnets. At the same time, the maximum speed is inversely proportional to the number of turns. Traditionally, high-torque, low-speed motor-wheel motors have lower efficiency than high-speed electric drives. This is due to the need to increase the number of turns on the motor windings to enhance the magnetic field. At the same time, the total electrical resistance of the windings increases, heat dissipation increases, and the useful power of the electric drive decreases. In the electric motor design proposed here, the used ratio of the number of permanent magnets and electromagnets, as well as their structural placement, allows to obtain the most uniform magnetic flux localized in the right place.

This makes it possible to significantly increase the value of the motor torque without increasing the number of turns and, accordingly, to do without an increase in heat loss due to heat generation and without reducing the efficiency. Having the value of the efficiency and efficiency of the electric motor at the level of classic high-speed electric motors, this useful model allows you to save all the advantages of "motor-wheel" constructions for use in vehicles.

Pairs of electromagnets are usually connected in a single circuit when assembling the electric motor. Depending on the destination, one or another connection method is chosen for all pairs. To increase the torque of the motor using a serial connection (Figure 3). Such electric motors are mainly intended for vehicles with increased power (tractors, buses, trucks, etc.). To increase the speed of rotation using a parallel connection (Figure 4). Typically, such electric motors are installed on scooters, motorcycles, electric cars, etc.

Pairs of electromagnets are independently connected to a control unit (CU) 9, which in turn is powered by a voltage source 10. The CU receives signals from rotor position sensors 6 located in the electric motor. The number of main sensors is equal to the number of phases N, plus in the case of an odd number of phases, one additional sensor is used. Information from an additional sensor allows you to implement more advanced algorithms for the operation of the switching device and practically eliminate the characteristic jerks when starting the electric motor with overload, and also significantly improve the characteristics of the electric motor at startup.

The sensors 6 are offset relative to each other by an angle of 360 / N phase degrees, and relative to electromagnets by 180 / N phase degrees. For a 3-phase electric motor, the angle between the sensors will be 120 phase degrees, and the angle of displacement relative to the solenoids will be 60 phase degrees (Figure 5 (a), (b)). Figure 5 (a) presents diagrams of the signals of HA, HB, HC from the sensors corresponding to phases A, B, C and the signal from the additional HD sensor. Figure 5 (b) presents the output signals of PA, PB, PC with control unit for the corresponding phases. The shift of the signal up to 60 degrees depends on the load and speed. The offset is calculated by the controller and changes constantly when the motor is running.

The electric motor, which has a separate connection of pairs of electromagnets to the control unit, allows greater flexibility in the choice of modes of its rotation, as well as the implementation of effective recovery of kinetic energy. For each electric motor, there is a torque constant K _t (Nm / A) and a constant frequency of rotation K _v (rpm / V). They are determined by the combination of design features of the electric motor. Separate control of electromagnets allows you to change the constants of an electric machine at the level of the control system.

To obtain the maximum value of K _t and the minimum value of K _v in the start mode from a standstill and to reduce the amount of current consumed, the control unit provides a star-type phase connection. The maximum voltage in this case at each phase is V _P = V / (N-1), where V is the voltage of the power source, N is the number of phases of the electric motor. Phase switching of the type "triangle" allows you to get a higher value of K _v and, accordingly, a higher speed at a fixed supply voltage. In cruising mode and in maximum speed mode, separate phase control with voltage on each phase V _P = V is used.

Figure 6 presents the electrical circuit of the phase switching for a 3-phase electric motor with phases A, B, C and a parallel connection of electromagnets in pair. With the keys 23 and 24 open, the keys 21-32 work, changing the polarity of the corresponding phase. This is a separate phase connection, when each works independently. When connecting keys 33 and 34, keys 27-32 are excluded from work, and only left keys 21-26 work and a star connection is obtained.

In the case of the number of electromagnets greater than twice the number of phases, their pairs are combined into phase groups. The number of such groups is equal to the number of phases, and the number of electromagnets in each phase group is the same. A single control signal is applied to each group. Within a group, electromagnets can be connected in series or in parallel. The switching of electromagnets is carried out by the control unit, and it can also occur in dynamic mode. The control unit provides a sinusoidal control signal to the electromagnets, the phase displacement of which can be dynamically changed in the range from -60 to 0 phase degrees.

To save part of the kinetic energy of the vehicle into the battery in the form of electric energy, a recuperation mode is provided in this utility model. To implement this mode of winding, a pair of electromagnets can be included in the power supply circuit through a diode bridge (Fig.7). Moreover, all pairs of electromagnets in the phase group (A, B, C) are connected in series. For the efficiency of the recovery process, it is preferable that the diode bridge contains diodes (D ₁ -D ₄ , D ₅ -D ₈ , D ₉ -D ₁₂ ) with a speed of 40 to 200 ns.

To implement the recovery mode, an inductive step-up DC-converter 11 can also be used (Fig. 8). It is usually installed between the positive output of the circuit and the positive contact of the battery 10. Structurally, such a converter can be included in the control unit. Such a pulsed inductive step-up voltage converter (most often referred to as a DC-DC converter in the technical literature) is a kind of DC transformer: at the input it loads the generator (the electric motor works as a generator during recovery) with the maximum current and receiving a small voltage, and at the output, the voltage necessary for charging the battery, but with less current. The efficiency of such converters on a modern elemental base is 95-98%, which allows them to be used effectively in the recovery system for vehicles.

Depending on the purpose, the utility model can be implemented in electric motors having different housing designs. For example (Figure 10 (a)), for electric bikes, scooters, electric cars, etc. preferably, the stator 12 is fixedly mounted in the housing 13, and the rotor 14 is connected to the movable rim 15 of the wheel. Smooth rotation is provided by bearings 16.

For a number of other applications (electric lifts, the main rotor of an airplane or helicopter, propellers, etc.), it is preferable to provide rotation of the motor shaft with the housing stationary (Figure 10 (b)). In this case, the rotor 14 is rigidly connected to the rotating sleeve 17 of the electric motor. The stator is fixed in the housing 18. Smooth rotation provide bearings 19.

Implementation examples: Example 1.

A line of unified electric drives for electric vehicles with a wide range of performance characteristics, depending on the specific design of the electric machine and software settings, has been developed.

Figure 10 (a) presents the dynamic characteristics of the electric drive designed for urban front-wheel drive car. The electric drive system consists of two electric motors - one per drive wheel. Graph 1 reflects the total moment of the electric drive, graph 2 - total power.

Rated total power: 48.5 kW (65 hp);

Maximum total power: 105 kW (141 hp);

Frequency of rotation of idling: 1490 rpm (corresponds to a speed of about 150 km / h);

Maximum total torque: 1150 Nm;

Mass of two electric motors: 59 kg;

Diameter of electric motors: 380 mm;

The length of one electric motor: 145 mm;

Supply voltage: 288 V;

Expected energy consumption in the urban cycle: 11-13 kW ^* h / 100 km;

The expected acceleration time of 0-100 km / h: 9.5 seconds.

Example 2:

Based on this utility model, a power plant designed for an electric sports car was developed. The drive consists of 4 electric motors - one for each wheel, power switching modules and a control system with interaction interfaces with a multimedia system and the possibility of expanding the system of separate traction control on wheels. Figure 10 (b) presents the dynamic characteristics of the electric drive. Graph 3 reflects the total moment of the electric drive, graph 4 - total power.

Rated total power: 240 kW (326 hp)

Maximum total power: 450 kW (612 hp)

Frequency of rotation of idling: 2380 rpm

Maximum total torque: 3720 Nm

Mass of four electric motors: 132 kg

Diameter of electric motors: 380 mm

Width of one electric motor: 145 mm

Supply voltage: 288 V

Expected acceleration time 0-100 km / h: 3.5 sec

Expected acceleration time 0-200 km / h: 8.0 seconds

Expected top speed: 250 km / h

Claims (22)

1. Brushless DC motor, including: an internal rotor containing individual permanent magnets uniformly spaced around a circle with an alternating direction of the magnetic field; an external stator containing two identical groups of electromagnets located circumferentially on different sides of the rotor opposite each other so that the axis of the electromagnet coils are parallel to the axis of rotation; rotor position sensors; an electromagnet control unit, characterized in that the number of phases N of the electric motor can be any number from a number N = 2, 3, 4, 6; the number m of electromagnets in each group is a multiple of the number of phases; the number n of poles of permanent magnets on one side of the rotor is even, not a multiple of the number of phases, greater than the number m of electromagnets in the group and not a multiple of their number; the number L of rotor position sensors is not less than the number of phases. 2. The electric motor according to claim 1, characterized in that the electromagnets have horseshoe-shaped cores and n> 2m. 3. The electric motor according to claim 1, characterized in that the number of phases N is odd and the number of rotor position sensors is N + 1. 4. The electric motor according to claim 1, characterized in that the number of phases N is even and the number of rotor position sensors is N. 5. The electric motor according to claim 1, characterized in that each of the electromagnets has an independent connection to the control unit. 6. The electric motor according to claim 2, characterized in that the angular distance between the centers of the teeth of the electromagnet is equal to the angular distance between the centers of adjacent magnetic poles on one side of the rotor. 7. The electric motor according to claim 2, characterized in that the electromagnet coils have the opposite direction of winding. 8. The electric motor according to claim 2, characterized in that the coils of electromagnets placed on the teeth, which are located opposite each other, have the same direction of the winding. 9. The electric motor according to claim 2, characterized in that the electromagnets located opposite each other are connected in a single circuit and form a pair. 10. The electric motor according to claim 9, characterized in that the electromagnets in a pair are connected in series. 11. The electric motor according to claim 9, characterized in that the electromagnets in pair are connected in parallel. 12. The electric motor according to claim 9, characterized in that the pairs of electromagnets located opposite each other are connected in phase groups, the number of which is equal to the number of phases, and the number of electromagnets in each phase group is the same. 13. The electric motor according to claim 12, characterized in that the switching of the pairs of electromagnets in the phase group is sequential. 14. The electric motor according to claim 12, characterized in that the switching of the pairs of electromagnets in the phase group is parallel. 15. The electric motor according to claim 12, characterized in that the control unit provides switching between serial or parallel switching of pairs of electromagnets in the phase group. 16. The electric motor according to claim 9, characterized in that the windings of a pair of electromagnets are included in the power circuit through a diode bridge. 17. The motor according to clause 16, wherein the diode bridge contains diodes with a speed of 40 to 200 ns. 18. The electric motor according to claim 1, characterized in that it further comprises an inductive step-up DC-DC converter. 19. The electric motor according to claim 1, characterized in that it comprises a housing, the rim of which is connected to the rotor and made movable. 20. The electric motor according to claim 1, characterized in that it comprises a housing made stationary, and a movable shaft connected to the rotor. 21. The electric motor according to claim 1, characterized in that N = 3, m = 9, n = 24, L = 4. 22. The electric motor according to claim 1, characterized in that N = 4, m = 12, the number of permanent magnets on one side of the magnetic circuit is selected from a number of numbers n = 26, 30, 34, L = 4.

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