阅读说明：本技术 电动自行车的无刷马达的转子位置感测方法 (Rotor position sensing method of brushless motor of electric bicycle ) 是由 梁志鸿 陈淳和 廖忠義 于 2018-06-20 设计创作，主要内容包括：一种电动自行车的无刷马达的转子位置感测方法,该方法先对定子单元的其中二相绕组通予一直流电,待转子单元受定子单元线圈激磁的磁场的磁力吸引而枢转直到固定,接着再利用感测模块获取感测磁石的角度位置,并计算出感测磁石的角度位置相较于基准位置的枢转角度θ,接着于感测模块中输入转子单元的磁极数量,感测模块根据转子单元的磁极数量及枢转角度θ进行运算,最后控制单元接收感测模块的运算数据并以此结合感测模块所感测到的感测磁石的位置的实时信息对无刷马达进行控制。(A method for sensing rotor position of brushless motor of electric bicycle includes applying DC to two phase windings of stator unit, pivoting rotor unit until it is fixed by magnetic force of magnetic field excited by stator unit coil, obtaining angle position of sensing magnet by sensing module, calculating out pivot angle theta of angle position of sensing magnet compared with reference position, inputting number of magnetic poles of rotor unit in sensing module, carrying out calculation by sensing module according to number of magnetic poles of rotor unit and pivot angle theta, receiving operation data by control unit and controlling brushless motor by real-time information of position of sensing magnet sensed by sensing module.)

1. A method for sensing the position of the rotor of the brushless motor of an electric bicycle, the brushless motor is located at the five-way of the electric bicycle or the wheel axle of the front and rear wheels, characterized in that, the brushless motor includes a stator unit, a rotor unit, a sensing magnet, a sensing module and a control unit, the rotor unit has a driving shaft, the rotor unit and the stator unit are coaxially and rotatably located in the stator unit, the sensing magnet is fixed on the driving shaft of the rotor unit and can rotate synchronously with the rotor unit, the stator unit has a plurality of stator teeth, each stator tooth is wound with a coil, these coils form a U phase winding, a V phase winding and a W phase winding, the control unit is electrically connected to the sensing module, the sensing method includes the following steps:

s0: the sensing module is arranged on the surface of the shell of the brushless motor and is adjacent to the sensing magnet;

s1: electrically connecting the positive end of the direct current to one of the U-phase winding, the V-phase winding and the W-phase winding, and electrically connecting the negative end of the direct current to the other of the U-phase winding, the V-phase winding and the W-phase winding;

s2: when the rotor unit is attracted by the magnetic force of the magnetic field excited by the stator unit coil to pivot until the rotor unit is fixed, the sensing magnet is driven to pivot until the sensing magnet is fixed, and the position of the sensing magnet is set to be an angle position;

s3: acquiring the angular position of the sensing magnet by using the sensing module, and calculating the pivoting angle theta of the angular position relative to a reference position;

s4: inputting the number of magnetic poles of the rotor unit into the sensing module, and calculating the sensing module according to the number of magnetic poles of the rotor unit and the pivot angle θ obtained in S3;

s5: the control unit receives the operation data of S4 and controls the operation of the brushless motor by combining the real-time information of the position of the sensing magnet sensed by the sensing module.

2. The method of claim 1, wherein in step S2, the sensing magnet has a pair of opposite sensing poles (N pole and S pole), and the pair of sensing poles are distributed along a radial direction of the driving shaft.

3. The method as claimed in claim 1, wherein the sensing magnet is fixed to an end surface of the driving shaft, and the sensing magnet is capable of pivoting coaxially with the driving shaft.

4. The method as claimed in claim 1, wherein the sensing module and the sensing magnet are disposed on the housing of the brushless motor in the axial direction of the driving shaft without contact in S3.

5. The method of claim 4, wherein the sensing module is perpendicular to the axial direction of the driving shaft and parallel to the sensing magnetic pole.

6. The method of claim 1, wherein the number of the stator teeth is a multiple of 3.

7. The method as claimed in claim 1, wherein the sensing module has a microprocessor and a storage unit, and the operations of S3 through S4 are performed by the microprocessor of the sensing module and stored in the storage unit.

8. The method as claimed in claim 1, wherein in step S3, the sensing module is capable of obtaining the direction and pivoting speed of the sensing magnetic pole of the sensing magnet.

Technical Field

The present invention relates to a method for sensing a position of a rotor of a brushless motor of an electric bicycle.

Background

In recent years, due to the improvement of health and environmental awareness, mobile vehicles which are used for sports and do not discharge exhaust gas, such as electric bicycles, are popular among many people, most of the existing electric bicycles are provided with motors mounted on five-way joints or wheel shafts of front and rear wheels, and the physical burden of a user is relieved by driving chains or wheels through the motors.

Compared with the conventional brush motor, the brushless motor has higher efficiency and torque density, and therefore is widely applied to electric bicycles, in order to accurately grasp the pivoting position of the rotor to maintain the commutation requirement of magnetic pole continuity on the stator, the current practice is to install 3 hall sensors between the stator teeth, and to estimate the pivoting position of the rotor according to the signals obtained by the hall sensors, such a practice has a very strict requirement on the relative positions of the hall sensors, the sensing magnets, the stator and the rotor, and the erroneous or deviated placement may cause the position of the rotor to be inconsistent with the actual position, which may result in inaccurate phase switching of the stator, and the motor operation efficiency is reduced or a pause occurs, so manufacturers often need to consume a lot of manpower and time in the alignment and correction processes of the hall sensors.

Disclosure of Invention

The present invention provides a method for sensing a rotor position of a brushless motor of an electric bicycle, which can reduce the adjustment process of relative positions among a hall sensor, a sensing magnet, a stator and a rotor during manufacturing, thereby reducing the production cost and improving the stability of quality.

To achieve the above object, the present invention provides a method for sensing a rotor position of a brushless motor of an electric bicycle, the brushless motor can be disposed at a bottom bracket of the electric bicycle or at a wheel axle of a front wheel and a rear wheel, it is characterized in that the brushless motor comprises a stator unit, a rotor unit, a sensing magnet, a sensing module and a control unit, the rotor unit is provided with a driving shaft, the rotor unit and the stator unit are coaxially and rotatably arranged in the stator unit, the sensing magnet is fixedly arranged on the driving shaft of the rotor unit and can synchronously rotate with the rotor unit, the stator unit is provided with a plurality of stator tooth parts, coils are wound on the stator tooth parts, the coils form a U-phase winding, a V-phase winding and a W-phase winding, the control unit is electrically connected to the sensing module, and the sensing method comprises the following steps:

s0: the sensing module is arranged on the surface of the shell of the brushless motor and is adjacent to the sensing magnet.

S1: the positive end of the direct current is electrically connected to one of the U-phase winding, the V-phase winding or the W-phase winding, and the negative end of the direct current is electrically connected to the other of the U-phase winding, the V-phase winding or the W-phase winding.

S2: when the rotor unit is attracted by the magnetic force of the magnetic field excited by the stator unit coil to pivot until the rotor unit is fixed, the sensing magnet is driven to pivot until the sensing magnet is fixed, and the position of the sensing magnet is set to be an angle position.

S3: the angular position of the sensing magnet is acquired by the sensing module, and the pivoting angle theta of the angular position relative to a reference position is calculated.

S4: the number of magnetic poles of the rotor unit is input into the sensing module, and the sensing module performs calculation according to the number of magnetic poles of the rotor unit and the pivot angle θ obtained in S3.

S5: the control unit receives the operation data of S4 and controls the brushless motor by combining the real-time information of the position of the sensing magnet sensed by the sensing module.

Optionally, in S2, the sensing magnet has an opposite sensing magnetic pole (N pole and S pole), and the pair of sensing magnetic poles are distributed along the radial direction of the driving shaft.

Optionally, the sensing magnet is fixedly disposed on an end surface of the driving shaft, and the sensing magnet is capable of pivoting coaxially with the driving shaft.

Optionally, in S3, the sensing module and the sensing magnet are disposed on the housing of the brushless motor adjacent to each other in the axial direction of the driving shaft without contacting each other.

Optionally, the sensing module is perpendicular to the axial direction of the driving shaft and parallel to the sensing magnetic pole.

Optionally, the number of stator teeth is a multiple of 3.

Optionally, the sensing module has a microprocessor and a storage unit, and the operations of S3 to S4 are performed by the microprocessor of the sensing module and stored in the storage unit.

Optionally, in S3, the sensing module senses the direction, position and pivoting speed of the magnetic pole of the sensing magnet.

Therefore, the relative position between the sensing magnet and the sensing module can be obtained through the steps, and since the stator unit and the sensing module do not move relatively and the rotor unit and the sensing magnet do not move relatively, the obtaining of the relative position between the sensing magnet and the sensing module also means the obtaining of the relative position between the rotor unit and the stator unit. That is, the present invention can accurately determine the position of the rotor unit through the above steps without the time-consuming and labor-consuming adjustment process for the relative positions of the hall sensor, the sensing magnet, the stator and the rotor as in the prior art, thereby effectively reducing the production cost and improving the quality stability.

The detailed features and steps of the method for sensing the rotor position of the brushless motor of an electric bicycle according to the present invention will be described in the following description. However, those skilled in the art should understand that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Drawings

The present invention provides a method for sensing a rotor position of a brushless motor of an electric bicycle, which is described in detail below with reference to the accompanying drawings, wherein:

fig. 1 is a flowchart illustrating a rotor position sensing method of a brushless motor of an electric bicycle according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a brushless motor of an electric bicycle according to an embodiment of the present invention.

FIG. 3 is a schematic view of the driving shaft and the sensing magnet according to the embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating a reference position of a magnet of a brushless motor of an electric bicycle according to an embodiment of the present invention.

FIG. 5 is a view similar to FIG. 4, mainly illustrating the schematic diagram of sensing the angular position of the magnet in step S2.

Wherein, the reference numbers:

s0, S1, S2, S3, S4, S5

1 brushless motor 3 casing

10 stator unit

20 rotor unit 22 drive shaft

24 end face

30 sensing magnet 32 sensing magnetic pole

40 sensing module

P0 reference position P1 angular position

Detailed Description

It should be noted that all terms used in the description of the present invention are exemplary description terms that can be understood by a person having ordinary skill in the art, and the terms used in the description of the present invention are directional terms such as "front", "upper", "lower", "rear", "left", "right", "top", "bottom", "inner", and "outer", and are exemplary description terms based on a normal use direction, and are not intended to limit the scope of claims.

Furthermore, as used in the claims, the singular forms "a", "an" and "the" include plural referents. Thus, for example, reference to "a component" means one or more of the component, and includes equivalents thereof known to those skilled in the art. All conjunctions used in a similar sense are to be understood in the broadest sense and the particular shapes and structural features or technical terms described in the specification are likewise to be understood as including equivalent structural or technical terms to the functions which the particular structures or technical terms are capable of achieving.

Referring to the drawings, fig. 1 is a flowchart of the present embodiment, and fig. 2 is a schematic structural diagram of a brushless motor of an electric bicycle of the present embodiment. In the method for sensing the rotor position of the brushless motor of the electric bicycle according to the embodiment of the present invention, the brushless motor 1 may be disposed on a bottom bracket of the electric bicycle or on wheel shafts (not shown) of front and rear wheels, and the brushless motor 1 drives a chain or a wheel to assist a user to ride.

Referring to fig. 1 to 3, the brushless motor 1 includes a stator unit 10, a rotor unit 20, a sensing magnet 30, a sensing module 40 and a control unit (not shown), the rotor unit 20 has a driving shaft 22, wherein the sensing magnet 30 is fixedly disposed on an end surface 24 of the driving shaft 22 of the rotor unit 20, the sensing magnet 30 is capable of pivoting coaxially with the driving shaft 22, the sensing magnet 30 has an opposite sensing magnetic pole 32 (as shown in fig. 4), the sensing magnetic pole 32 includes an N magnetic pole and an S magnetic pole, an extending direction from the S magnetic pole to the N magnetic pole is defined as a direction of the sensing magnetic pole 32 of the sensing magnet 30 (as indicated by an arrow in fig. 4), and a direction of the sensing magnetic pole 32 is parallel to a radial direction of the driving shaft 22; the rotor unit 20 and the stator unit 10 are coaxially and rotatably disposed in the stator unit 10, the stator unit 10 has a plurality of stator teeth (not shown), the number of the stator teeth is a multiple of 3, coils are wound on each stator tooth, the coils form a U-phase winding, a V-phase winding and a W-phase winding, and the control unit is electrically connected to the sensing module 40. The sensing method comprises the following steps:

s0: the sensing module 40 is disposed on the surface of the housing 3 of the brushless motor 1 and adjacent to the sensing magnet 30.

S1: the positive end of the direct current is electrically connected to one of the U-phase winding, the V-phase winding and the W-phase winding, and the negative end of the direct current is electrically connected to the other of the U-phase winding, the V-phase winding and the W-phase winding. For example, the user can electrically connect the positive terminal of the dc power to the U-phase winding and the negative terminal of the dc power to the V-phase winding, and then the current enters from the U-phase winding and then flows out from the V-phase winding, so that the stator teeth wound by the U-phase winding and the V-phase winding generate magnetic force due to the magnetic field excited by the coil to attract the rotor unit 20 to pivot.

S2: when the rotor unit 20 is attracted by the magnetic force of the magnetic field excited by the coil of the stator unit 10 and pivots until fixed, the sensing magnet 30 is also driven by the rotor unit 20 and the driving shaft 22 to pivot until fixed, and the fixed position of the sensing magnet 30 is defined as an angular position P1 (as shown in fig. 5).

Please refer to fig. 4 and fig. 5 together. S3: the angular position P1 of the sensing magnet 30 is obtained by the sensing module 40, and the pivot angle θ of the angular position P1 with respect to a reference position P0 is calculated. The sensing module 40 and the sensing magnet 30 are disposed adjacent to each other in the axial direction of the driving shaft 22 without contacting each other, the sensing module 40 is perpendicular to the axial direction of the driving shaft 22 and parallel to the sensing magnetic pole 32, and the sensing module 40 can sense the position of the sensing magnet 30, sense the direction of the magnetic pole of the sensing magnet 30, and obtain the pivoting speed of the sensing magnet 30 through calculation.

S4: the number of magnetic poles of the rotor unit 20 is input into the sensing module 40, and the sensing module 40 performs calculation according to the number of magnetic poles of the rotor unit 20 and the pivot angle θ obtained in S3. The sensing module 40 includes a microprocessor (not shown) and a storage unit (not shown), and the operations of S3 to S4 are performed by the microprocessor of the sensing module and stored in the storage unit.

S5: the control unit receives the operation data of S4 and controls the operation of the brushless motor 1 by combining the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40.

The present invention is described below with reference to specific examples, but the scope of the present invention is not limited to these examples.

Referring to fig. 1 and 2, in the present embodiment, a brushless motor 1 having 12 stator teeth of a stator unit 10 is selected, a user first installs the sensing module 40 in the housing 3 of the brushless motor 1 and adjacent to the sensing magnet 30, wherein the sensing module 40 is an AsahiKASEI model AK7451 product, which can sense information such as a position and a pivoting state of the sensing magnet 30, but the user can select other products having similar functions. Then, the positive end of the dc power is electrically connected to the U-phase winding, and the negative end of the dc power is electrically connected to the V-phase winding, at this time, the current enters from the U-phase winding and then flows out from the V-phase winding, so that the magnetic force of the magnetic field excited by the coil is generated in the stator teeth wound by the U-phase winding and the V-phase winding to attract the rotor unit 20 to pivot until the rotor unit is fixed, as shown in fig. 5, at this time, the rotor unit 20 is at the angular position P1, in this example, the vertical line of the N-magnetic pole facing upward and the S-magnetic pole facing downward is used as the reference position P0 (as shown in fig. 4), in other possible embodiments, the boundary line of the N-magnetic pole and the S-magnetic pole may also be used as the reference position, in this example, the included angle θ between the pivoted angular.

Then, the number of magnetic poles of the rotor unit 20 is input into the sensing module 40, in this example, a rotor unit with 14 magnetic poles is selected, and since the magnetic poles of the rotor unit 20 are arranged at equal angular intervals, that is, the rotor unit 20 has a rotationally symmetric characteristic, it is inferred that the rotor unit 20 returns to a similar state after pivoting a fixed angle. The sensing module 40 performs calculation according to the number of magnetic poles of the rotor unit 20 and the acquired pivot angle θ. Finally, the control unit receives the operation data of the sensing module 40, and controls the operation of the brushless motor 1 by combining the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40, particularly the phase switching points of the U-phase winding, the V-phase winding and the W-phase winding.

In summary, the relative positions of the sensing magnet 30 and the sensing module 40 can be obtained through the above steps, and since there is no relative movement between the stator unit 10 and the sensing module 40 and there is no relative movement between the rotor unit 20 and the sensing magnet 30, obtaining the relative positions of the sensing magnet 30 and the sensing module 40 also means obtaining the relative positions between the rotor unit 20 and the stator unit 10, that is, the present invention can accurately grasp the position condition of the rotor unit 20 through the above steps. At this time, the control unit can precisely control the operation of the brushless motor 1 only by matching with the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40. Compared with the traditional time-consuming and labor-consuming adjustment process of the relative positions among the Hall sensor, the sensing magnet, the stator and the rotor in a manual mode, the phase switching device can effectively reduce production cost and maintain quality stability, and moreover, the position of the rotor unit can be accurately grasped through the steps, so that the phase switching point can be more accurate, and the motor efficiency can be effectively improved.

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.