TWI686050B - Rotor position sensing method of brushless motor of electric bicycle - Google Patents

Abstract

A rotor position sensing method for a brushless motor of an electric bicycle. The method first applies direct current to the two-phase windings of the stator unit. After the rotor unit is attracted by the magnetic force of the magnetic field excited by the stator unit coil and pivots until fixed, then Then use the sensing module to obtain the angular position of the sensing magnet, and calculate the pivot angle θ of the angular position of the sensing magnet compared to the reference position, then input the number of magnetic poles of the rotor unit in the sensing module to sense The module performs calculation according to the number of magnetic poles of the rotor unit and the pivot angle θ to obtain the switching angle Φ, and finally the control unit receives the switching angle Φ obtained by the operation of the sensing module and combines the sensed by the sensing module Control the brushless motor with real-time information about the position of the magnet.

Description

Rotor position sensing method of brushless motor of electric bicycle

The invention relates to an electric bicycle sensing method, in particular to a rotor position sensing method of a brushless motor of the electric bicycle.

In recent years, due to increased awareness of health and environmental protection, mobile vehicles such as electric bicycles that are both sporty and do not emit exhaust gas have been loved by many people. Most current electric bicycles are equipped with motors on the five-way or front and rear wheels. At the wheel axle, the chain or wheel is driven by the motor to reduce the physical burden on the user. However, in addition to affecting the conversion efficiency of the power, the quality of the motor also affects the smoothness of the riding place, which has a very important position.

Compared with traditional brushed motors, brushless motors have higher efficiency and torque density, so they are widely used in electric bicycles. In order to accurately grasp the pivot position of the rotor and maintain the continuity of the magnetic poles on the stator, commutation The current practice is to install three Hall sensors between the teeth of the stator. The signal obtained by the Hall sensors can be used to infer the position of the rotor pivot. This method is suitable for Hall sensors and sensing. The relative position of the magnet, stator and rotor has strict requirements. Wrong or deviation placement will cause the estimated rotor position to be inconsistent with the actual position, which will lead to inaccurate phase switching of the stator and reduce the efficiency of the motor or setback. Therefore, manufacturers often need to spend a lot of manpower and time on the alignment and calibration process of each Hall sensor.

The reason is that the object of the present invention is to provide a rotor position sensing method for a brushless motor of an electric bicycle, which can reduce the adjustment process of the relative position between the Hall sensor, the sensing magnet, the stator and the rotor during manufacturing, In turn, it reduces production costs and improves the stability of quality.

In order to achieve the above object, the present invention provides a rotor position sensing method for a brushless motor of an electric bicycle. The brushless motor can be installed on the five-way of the electric bicycle or on the axles of the front and rear wheels. The characteristic is 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 drive shaft, the rotor unit is coaxial with the stator unit and It is rotatably arranged in the stator unit. The sensing magnet is fixed on the drive shaft of the rotor unit and can rotate synchronously with the rotor unit. The stator unit has a plurality of stator teeth, which are wound around each of the stator teeth Coils are provided. 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. The sensing method includes the following steps:

S0: The sensing module is arranged on the surface of the housing of the brushless motor and is adjacent to the sensing magnet.

S1: electrically connect the positive end of the direct current to one of the U-phase winding, the V-phase winding or the W-phase winding, and electrically connect the negative end of the direct current to the U-phase winding, the V-phase winding or the The other of 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 and pivots until fixed, the sensing magnet will also be driven to pivot until fixed, and the position of the sensing magnet is set to an angular position .

S3: Using the sensing module, the angular position of the sensing magnet has been obtained, and the pivot angle of the angular position compared to a reference position is calculated as θ.

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 acquired by S3 to obtain a switching angle Φ.

S5: The control unit receives the switching angle Φ obtained by the operation of S4 and combines the real-time information on the position of the sensing magnet sensed by the sensing module to control the brushless motor.

Optionally, in S2, the sense magnet has a relative sense pole (N pole and S pole), and the pair of sense poles are distributed along the radial direction of the drive shaft.

Optionally, the sensing magnet is fixed on one end surface of the driving shaft, and the sensing magnet can pivot coaxially with the driving shaft.

Optionally, in S3, the sensing module and the sensing magnet are arranged on the housing of the brushless motor adjacent to but not in contact with the axial direction of the drive shaft.

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

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

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

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

With this, the present invention can obtain the relative position of the sensing magnet and the sensing module through the foregoing steps. Since there is no relative movement between the stator unit and the sensing module, the rotor unit and the sensing magnet Relative motion, so knowing the relative position of the sensing magnet and the sensing module also means knowing the relative position between the rotor unit and the stator unit. In other words, the present invention can accurately grasp the position of the rotor unit through the foregoing steps, without the need for time-consuming and labor-intensive processing of the relative position between the Hall sensor, the sensing magnet, the stator and the rotor as in the prior art Adjustment process, it can effectively reduce production costs and improve the stability of quality.

The detailed features and steps of the rotor position sensing method for a brushless motor of an electric bicycle provided by the present invention will be described in the subsequent description. However, those of ordinary knowledge in the field of the present invention should be able to understand that these detailed descriptions and specific embodiments listed for implementing the present invention are only used to illustrate the present invention, and are not intended to limit the scope of the patent application of the present invention.

The first thing to explain is that the terms used in the description provided by the present invention are all exemplary descriptive terms that can be understood by those with ordinary knowledge in the technical field. The terms “front”, “upper”, Directional adjectives such as "down", "back", "left", "right", "top", "bottom", "inner", and "outer" are only exemplary descriptions based on the normal direction of use The term is not intended to limit the scope of the claim.

Furthermore, quantifiers such as "a", "an", and "the" as used in the patent application scope of the invention all include plural meanings. Thus, for example, a description of "an element" refers to one or more elements, and includes equivalent replacements known to those of ordinary skill in the art. All conjunctions used in similar situations should also be understood in the broadest sense. The specific shapes and structural features or technical terms described in the description should also be understood to include functions that can be achieved by specific structures or technical terms Equivalently replaces structural or technical terms.

Please refer to the drawings first. FIG. 1 is a flowchart of this embodiment, and FIG. 2 is a schematic structural diagram of a brushless motor of an electric bicycle of this embodiment. A rotor position sensing method for a brushless motor of an electric bicycle according to an embodiment of the present invention. The brushless motor 1 can be installed on the five-way of the electric bicycle or on the axles of the front and rear wheels (not shown in the figure) ), assisting the user to ride by the brushless motor 1 driving the chain or wheels.

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 drive shaft 22, The sensing magnet 30 is fixed on an end surface 24 of the driving shaft 22 of the rotor unit 20, and the sensing magnet 30 can pivot coaxially with the driving shaft 22, and the sensing magnet 30 has a relative The sensing magnetic pole 32 (as shown in FIG. 4), the sensing magnetic pole 32 includes an N magnetic pole and an S magnetic pole, and the extending direction from the S magnetic pole to the N magnetic pole is defined as the sensing magnetic pole of the sensing magnet 30 The direction of 32 (such as the arrow in Figure 4), the direction of the sensing magnetic pole 32 is parallel to the radial direction of the drive shaft 22; the rotor unit 20 is coaxial with the stator unit 10 and rotatably provided 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, and coils are wound around each of the stator teeth A U-phase winding, a V-phase winding and a W-phase winding are formed, and the control unit is electrically connected to the sensing module 40. This sensing method includes the following steps:

S0: The sensing module 40 is disposed on the surface of the housing 3 of the brushless motor 1 and is adjacent to the sensing magnet 30.

S1: The positive terminal 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 terminal of the direct current is electrically connected to the U-phase winding, the V-phase winding and the The other of the W-phase winding. For example, the user can electrically connect the positive terminal of the direct current to the U-phase winding, and electrically connect the negative terminal of the direct current to the V-phase winding. At this time, the current will enter from the U-phase winding and flow out from the V-phase winding. In this way, the stator teeth wound around the U-phase winding and the V-phase winding will generate a 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 it is fixed, the sensing magnet 30 is also pivoted until it is fixed by the rotor unit 20 and the drive shaft 22 The fixed position of the sensing magnet 30 is defined as an angular position P1 (as shown in FIG. 5).

Please refer to Figure 4 and Figure 5 together. S3: Use the sensing module 40 to obtain the angular position P1 of the sensing magnet 30, and calculate the pivot angle of the angular position P1 compared to a reference position P0 as θ. Wherein, the sensing module 40 and the sensing magnet 30 are arranged adjacent to but not in contact with the axis of the driving shaft 22, and the sensing module 40 is perpendicular to the axis of the driving shaft 22 and is in contact with the The sensing magnetic poles 32 are parallel. In addition, the sensing module 40 can sense the direction of the magnetic poles of the sensing magnet 30 in addition to the position of the sensing magnet 30. The pivot speed of the magnet 30 is sensed.

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 acquired by S3 to obtain a switching angle Φ. The foregoing calculation system divides the rotor unit 20 by 360 degrees in one rotation by the number n of magnetic poles of the rotor unit to obtain an angle φ, where the number n of magnetic poles of the rotor unit is a multiple of 2, for example, in different implementations In the aspect, the number n of the magnetic poles may be, but not limited to, 2, 4, 6, 8 or 10. Next, define θ + N * φ = Φ as the switching angle, where N is an integer greater than or equal to 0. The sensing module 40 includes a microprocessor (not shown in the figure) and a storage unit (not shown in the figure). The S3 to S4 are calculated by the microprocessor of the sensing module and stored in the Storage unit.

S5: The control unit receives the switching angle Φ obtained by the operation of S4 and uses the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40 to control the operation of the brushless motor 1. Specifically, when the sensing module 40 senses that the sensing magnet 30 rotates to the switching angle Φ, it means that the rotor unit 20 reaches the phase switching point. At this time, the control unit will respond to the U-phase winding and the V The phase winding and the phase W winding are switched.

The present invention will be described below with specific examples, but the protection scope of the present invention is not limited to this example.

Please refer to FIG. 1 and FIG. 2, this example selects the brushless motor 1 with the number of stator teeth of the stator unit 10 as 12, the user first installs the sensing module 40 in the housing 3 of the brushless motor 1 It is adjacent to the sensing magnet 30, where the sensing module 40 is a product of AK7451 model of AsahiKASEI. The product can sense the position and pivot status of the sensing magnet 30, but the user can also Use other products with similar functions. Next, electrically connect the positive end of the direct current to the U-phase winding, and electrically connect the negative end of the direct current to the V-phase winding. At this time, the current will enter from the U-phase winding and then flow out from the V-phase winding. The stator teeth wound by the winding and the V-phase winding will generate the magnetic force of the magnetic field excited by the coil to attract the rotor unit 20 to pivot until fixed. As shown in FIG. 5, the rotor unit 20 is at the angular position P1. In the example, the vertical line with 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 between the N magnetic pole and the S magnetic pole can also be used as the reference In this example, the angle θ between the pivoted angular position P1 and the reference position P0 is 35 degrees.

Next, the number n of magnetic poles of the rotor unit 20 is input into the sensing module 40. In this example, the rotor unit 20 with the number of rotor magnetic poles n = 12 is selected. Since the magnetic poles of the rotor unit 20 are arranged at equal angular intervals , That is, the rotor unit 20 has a rotationally symmetrical characteristic, so it can be inferred that the rotor unit 20 will return to a similar state every time the rotor unit 20 pivots by a fixed angle, and the sensing module 40 according to the number of magnetic poles n And the obtained pivot angle θ for calculation. The foregoing calculation is to divide the rotor unit 20 by 360 degrees in one revolution by the number of magnetic poles of the rotor unit n=12 to obtain the angle φ=360 degrees/12=30 degrees, and then, The θ + N * φ = 35 degrees + N * 30 degrees = Φ is defined as the switching angle, where N is an integer greater than or equal to 0, in other words, the switching angle is located at Φ = 35, 65, 95, 125, 155 , 185, 215, 245, 275, 305, 335, and 365 (at 5 degrees of secondary circle), etc.

Finally, the control unit receives the switching angle Φ obtained by the operation of the sensing module 40 and combines the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40 to the brushless motor 1 Control of the operation of, especially for controlling the phase switching points of the U-phase winding, the V-phase winding and the W-phase winding. Specifically, when the sensing module 40 senses that the sensing magnet 30 rotates to the switching angle Φ, it means that the rotor unit 20 reaches the phase switching point, and at this time, the control unit will process the U-phase winding and the V-phase The phase of the winding and the W-phase winding are switched.

Another example is used to illustrate. In this example, the steps from S0 to S2 are the same as the previous example. Then, in step S3, the sensing module is used to obtain the angular position of the sensing magnet and calculate the angle The pivot angle θ of the position compared to the reference position is 7 degrees. In step S4, the number n of magnetic poles of the rotor unit 20 is 10. At this time, the sensing module 40 performs calculation based on the number n of magnetic poles of the rotor unit 20 and the obtained pivot angle θ. The rotor unit 20 pivots 360 degrees in one revolution divided by the number of magnetic poles of the rotor unit n=10 to obtain the angle φ=360 degrees/10=36 degrees, then, the θ + N * φ = 7 degrees + N * 36 degrees = Φ is defined as the switching angle, where N is an integer greater than or equal to 0, in other words, the switching angle is located at Φ=7, 42, 79, 115, 151, 187, ..., 295, 331, etc.

Finally, the control unit receives the switching angle Φ obtained by the operation of the sensing module 40 and combines the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40 to the brushless motor 1 Control of the operation of, especially for controlling the phase switching points of the U-phase winding, the V-phase winding and the W-phase winding. Specifically, when the sensing module 40 senses that the sensing magnet 30 rotates to the switching angle Φ, it means that the rotor unit 20 reaches the phase switching point, and at this time, the control unit will process the U-phase winding and the V-phase The phase of the winding and the W-phase winding are switched.

In summary, in this case, through the aforementioned steps, the relative position of the sensing magnet 30 and the sensing module 40 can be obtained. Since there is no relative movement between the stator unit 10 and the sensing module 40, the rotor unit 20 There is also no relative movement with the sensing magnet 30, so knowing the relative position of the sensing magnet 30 and the sensing module 40 also means knowing the relative position between the rotor unit 20 and the stator unit 10, that is, the present invention The position of the rotor unit 20 can be accurately grasped in steps. At this time, the control unit only needs to cooperate with the real-time information of the position of the sensing magnet 30 sensed by the sensing module 40 to accurately control the operation of the brushless motor 1. Compared with the traditional time-consuming and labor-intensive adjustment process of the relative position between the Hall sensor, the sensing magnet, the stator and the rotor through manual methods, this case can effectively reduce production costs and maintain stable quality In addition, in this case, the position of the rotor unit can be accurately grasped through the aforementioned steps, so that the phase switching point can be more accurate, which can effectively improve the motor performance.

Finally, it must be explained again that the constituent elements and steps disclosed in the foregoing embodiments of the present invention are only examples and are not intended to limit the patent scope of the present invention. Any simple structural retouching or changes made without departing from the spirit of the present invention , Or replacement with other equivalent components, should still fall within the scope covered by the patent application of the present invention.

S0, S1, S2, S3, S4, S5 ‧‧‧ Step 1 ‧ ‧ ‧ brushless motor 3 ‧ ‧ ‧ case 10 ‧ ‧ ‧ stator unit 20‧‧‧Rotor unit 22‧‧‧Drive shaft 24‧‧‧End face 30‧‧‧Magnet sensing 32‧‧‧Pole sensing 40 40‧‧‧ Sensing module P0‧‧‧Base position P1‧‧‧Angle position

The following describes the rotor position sensing method for a brushless motor of an electric bicycle provided by the present invention with examples and drawings, in which: FIG. 1 is a flowchart of 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. Figure 3 is an embodiment of the present invention, mainly showing the structure of the drive shaft and the sensing magnet. FIG. 4 is a schematic diagram of a sensing magnet of a brushless motor of an electric bicycle according to an embodiment of the present invention at a reference position. Fig. 5 is similar to Fig. 4 and mainly shows a schematic diagram of sensing the angular position of the magnet in step S2.

S0, S1, S2, S3, S4, S5‧‧‧

Claims (6)

A rotor position sensing method for a brushless motor of an electric bicycle. The brushless motor can be installed on the five-way of the electric bicycle or on the axles 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 drive shaft, the rotor unit is coaxial with the stator unit and rotatably disposed in the stator unit, the The sensing magnet is fixed on the drive shaft of the rotor unit and can rotate synchronously with the rotor unit. The stator unit has a plurality of stator teeth, and coils are wound on each of the stator teeth to 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 installed in the housing of the brushless motor The body surface is adjacent to the sensing magnet; S1: electrically connect the positive end of the direct current to the U-phase winding, the V-phase winding and the W-phase winding, and electrically connect the negative end of the direct current to the The other of U-phase winding, V-phase winding and 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 produce a pivot until fixed, the sensing magnet will also be driven And pivot until it is fixed, the position of the sensing magnet is set to an angular position, the sensing magnet has a relative sensing magnetic pole (N magnetic pole and S magnetic pole), the pair of sensing magnetic poles is along the diameter of the drive shaft Direction distribution; S3: use the sensing module to obtain the angular position of the sensing magnet, and calculate the pivot angle of the angular position compared to a reference position as θ, the sensing module can obtain the sense The direction and pivot speed of the magnetic pole of the magnetometer; S4: input the number of magnetic poles of the rotor unit 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 acquired by S3 to obtain a switching angle Φ; S5: The control unit receives the switching angle Φ obtained by the operation of S4 and combines the real-time information of the position of the sensing magnet sensed by the sensing module to control the operation of the brushless motor. A rotor position sensing method for a brushless motor of an electric bicycle as described in item 1 of the patent scope, wherein the sensing magnet is fixed on one end surface of the drive shaft, and the sensing magnet can be connected with the drive The shaft pivots coaxially. A rotor position sensing method for a brushless motor of an electric bicycle as described in item 1 of the patent scope, wherein in S3, the sensing module is adjacent to the sensing magnet along the axis of the drive shaft but It is provided on the housing of the brushless motor without contact. A rotor position sensing method for a brushless motor of an electric bicycle as described in item 4 of the patent application scope, wherein the sensing module is perpendicular to the axis of the drive shaft and parallel to the sensing magnetic pole. A rotor position sensing method for a brushless motor of an electric bicycle as described in item 1 of the patent application scope, wherein the number of the stator teeth is a multiple of 3. A rotor position sensing method for a brushless motor of an electric bicycle as described in item 1 of the patent scope, wherein the sensing module has a microprocessor and a storage unit, and the S3 to S4 are based on the sensing The microprocessor of the module performs calculations and stores them in the storage unit.

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