Sensorless internal permanent magnet synchronous motor and rotor mechanical angle detection method

Abstract

A sensorless built-in permanent magnet synchronous motor comprises a rotor, wherein the rotor comprises a rotor core and a plurality of permanent magnets embedded in the rotor core, wherein the magnetic poles of each two adjacent permanent magnets on the same end face of the rotor are different; a plurality of magnetic barriers and magnetic isolation bridges are arranged on the rotor core, wherein each magnetic barrier and magnetic isolation bridge are respectively adjacent to the outer side of the rotor, and each permanent magnet is provided with a magnetic barrier corresponding to the side close to the outer side of the rotor, wherein a pair of adjacent permanent magnets are respectively not provided with magnetic barriers, and two magnetic barriers respectively adjacent to the two adjacent permanent magnets are formed into a magnetic barrier group, and the width and thickness of each magnetic barrier group are respectively the same, and the widths of each magnetic barrier group are different; each permanent magnet is respectively provided with a magnetic isolation bridge between the outer side of the rotor, and two magnetic isolation bridges respectively adjacent to the two adjacent permanent magnets are formed into a magnetic isolation bridge group, and the length and thickness of each magnetic isolation bridge group are respectively the same, and the thicknesses of each magnetic isolation bridge group are different. The invention has low cost and small space volume. The invention also provides a rotor mechanical angle detection method.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motors, and more particularly to a sensorless built-in permanent magnet synchronous motor and a rotor mechanical angle detection method thereof. Background Art

[0002] Permanent magnet synchronous motors have the advantages of large torque, high power density and high efficiency, and are widely used in automatic control systems. At present, permanent magnet synchronous motors use position sensors to obtain the position information of the motor rotor. However, the use of position sensor control technology to obtain the position information of the motor rotor has the following defects:

[0003] 1. Position sensors will increase the manufacturing cost of the motor. Traditional permanent magnet synchronous motors usually need to rely on external position sensors, such as Hall sensors, rotary encoders, etc., to detect the rotor angle. The addition of such sensors will invisibly increase the manufacturing cost of the motor, especially high-precision sensors, which are more expensive.

[0004] 2. The position sensor will increase the size of the motor. The position sensor usually needs to be installed on the rotor or stator of the motor, which complicates the motor structure and increases the size. Especially in places with strict space requirements, such as power tools and electric vehicles, the size of the position sensor may affect the overall design and use efficiency of the motor;

[0005] 3. Sensors will reduce the reliability of the motor control system in harsh environments: Most position sensors on the market, such as photoelectric encoders, Hall sensors, etc., have high requirements for the working environment. They may fail or perform poorly in harsh environments such as high temperature, humidity, and dust, reducing the adaptability and reliability of the motor control system in harsh environments.

[0006] Based on this, some people have designed permanent magnet synchronous motors without position sensors. This type of permanent magnet synchronous motor uses sensorless technology, such as back-electromotive force method, high-frequency injection method, etc., to estimate the rotor position. However, this type of sensorless technology can only estimate the electrical angle and motor speed of the motor, but cannot estimate the mechanical angle of the rotor. It cannot be applied to scenarios that require the mechanical angle of the rotor, such as joint modules, CNC machine tools, etc.

[0007] In view of this, the applicant conducted in-depth research on this basis, which led to the emergence of this case. Summary of the invention

[0008] The object of the present invention is to provide a sensorless interior permanent magnet synchronous motor with small size, low cost and high reliability.

[0009] Another object of the present invention is to provide a sensorless method for detecting the mechanical angle of the rotor of an interior permanent magnet synchronous motor, which can detect the mechanical angle of rotation.

[0010] To achieve the above object, the solution of the present invention is:

[0011] A sensorless built-in permanent magnet synchronous motor, characterized in that: it includes a motor body, the motor body includes a rotor, the rotor includes a rotor core and a plurality of permanent magnets embedded in the rotor core, each of the permanent magnets is sequentially arranged at intervals along the circumference of the rotor core, and on the same end face of the rotor, the magnetic poles of every two adjacent permanent magnets are different from each other; a plurality of magnetic barriers and magnetic isolation bridges are provided on the rotor core, each of the permanent magnets is provided with the magnetic barrier corresponding to the side close to the outer side of the rotor, wherein a pair of permanent magnets close to each other are not provided with magnetic barriers, and each of the magnetic barriers is respectively arranged along the The rotor core is arranged at intervals in the circumferential direction, with the two magnetic barriers respectively adjacent to two permanent magnets close to each other forming a magnetic barrier group, in each group of the magnetic barriers, the width and thickness of the two magnetic barriers are respectively the same, and the widths of each magnetic barrier group are different; a magnetic isolation bridge is respectively arranged between each permanent magnet and the outer side of the rotor, and each magnetic isolation bridge is respectively arranged at intervals in the circumferential direction of the rotor core, with the two magnetic isolation bridges respectively adjacent to two permanent magnets close to each other forming a magnetic isolation bridge group, in each group of the magnetic isolation bridge group, the length and thickness of the two magnetic isolation bridges are respectively the same, and the thicknesses of each magnetic isolation bridge group are different.

[0012] In the cross section of the rotor core, the two permanent magnets without the magnetic barrier are the first permanent magnet group, the extended line between the centers of the two first permanent magnet groups and the axis of the rotor core is the symmetry line, and the rotor is symmetrically arranged along the symmetry line.

[0013] Taking the first permanent magnet group as a starting point, the widths of the magnetic barrier groups are arranged to gradually increase along both sides.

[0014] The rotor core is provided with a plurality of through holes, and two ends of each through hole extend along two end surfaces of the rotor core respectively, and each through hole forms the magnetic barrier respectively.

[0015] Taking the first permanent magnet group as a starting point, the thickness of each magnetic isolation bridge group is gradually reduced along both sides.

[0016] The permanent magnets adjacent to each other are arranged in an eight-shaped pattern.

[0017] The motor body further comprises a stator, which is sleeved on the outer side of the rotor, and an air gap is arranged between the stator and the rotor, and each of the magnetic isolation bridges and each of the magnetic barriers are respectively adjacent to the air gap.

[0018] A rotor mechanical angle detection method adopts the above-mentioned built-in permanent magnet synchronous motor, and the specific detection method is as follows:

[0019] S1. Obtain a corresponding relationship table: A1. When the motor body is stopped, the motor body is positioned at n electrical angle zero points in sequence, where the value of n matches the number of pole pairs of the motor body, and the n electrical angle zero points respectively divide the position of the rotor into n mechanical sectors, and each of the mechanical sectors corresponds to mechanical sector 1, mechanical sector 2, mechanical sector 3 to mechanical sector n;

[0020] A2. At each position of the electrical angle of zero, high-frequency voltage signals are injected into the AB phase, BC phase and AC phase of the motor body respectively, and the steady-state amplitude of the current response between the AB phases is measured. i AB , the steady-state amplitude of the current response between the BC phases i BC , the steady-state amplitude of the current response between AC phases i AC ; Then record the current response steady-state amplitude corresponding to each electrical angle zero degree i AB , i BC , i AC , to obtain the current response steady-state amplitude corresponding to each of the mechanical sectors, and obtain a corresponding relationship table;

[0021] S2. Determine the initial mechanical sector: before the motor body needs to be started, first position the motor body to the nearest electrical angle zero point, inject high-frequency voltage signals into the AB phase, BC phase and AC phase of the motor body, respectively, and measure the current response steady-state amplitude of the AB phase, BC phase and AC phase respectively. i AB , i BC , i AC , and then obtaining the mechanical sector where the rotor is currently located through the corresponding relationship table in step A2;

[0022] S3, determining the mechanical sector: after the motor body is started, a position sensorless control algorithm is used to detect the rotor electrical angle in real time, and the mechanical sector is updated by one every time the rotor electrical angle increases by 360°. After the mechanical sector is updated to the mechanical sector n, the mechanical sector n is reset to the mechanical sector one when it is updated again;

[0023] S4. Obtaining the mechanical angle of the rotor: using a mechanical angle calculation formula to obtain the mechanical angle of the rotor, the mechanical angle calculation formula is: ,in θ m is the mechanical angle, θ e is the rotor electrical angle, S For the mechanical sector, P n is the pole pair number.

[0024] The position sensorless control algorithm is a pulse high frequency voltage signal injection method.

[0025] In step A1 and step S2, the amplitude of the high-frequency voltage signal is 100V and the frequency is 250Hz.

[0026] After adopting the above-mentioned sensorless built-in permanent magnet synchronous motor, the following beneficial effects are achieved: magnetic barriers and magnetic isolation bridges are introduced into the rotor, and the widths of the corresponding magnetic barrier groups are different, and the thicknesses of the corresponding magnetic isolation bridge groups are different, so that the motor body forms an asymmetric topological structure, so that the inductance of the motor body exhibits a mechanical periodic characteristic, and the mechanical angle of the rotor is obtained through the mechanical periodic characteristic, that is, the position of the rotor is obtained. The present invention has a simple structure, requires less modification to the motor body, has low cost, strong reliability, and a small spatial volume of the motor body.

[0027] The above-mentioned rotor mechanical angle detection method has the following beneficial effects: the present invention divides the motor body into multiple mechanical sectors through an asymmetric motor topology structure, and then combines a position sensorless control algorithm to obtain the mechanical angle of the rotor, and the detection is simple and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the built-in permanent magnet synchronous motor of the present invention.

[0029] Figure 2 It is a structural schematic diagram of the interior permanent magnet synchronous motor of the present invention from another angle.

[0030] Figure 3 This is a diagram showing the relationship between the rotor mechanical angle, electrical angle and mechanical sector in the present invention.

[0031] Figure 4 This is the inductance waveform diagram of the motor body in the present invention.

[0032] Figure 5 This is the FFT analysis diagram of the inductance waveform of the motor body in the present invention.

[0033] In the picture;

[0034] 100-motor body; 21-stator core; 22-winding coil; 3-air gap; 4-rotor core; 5-permanent magnet; 6-magnetic barrier; 7-magnetic isolation bridge; 8-symmetry line. DETAILED DESCRIPTION

[0035] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0036] A sensorless internal permanent magnet synchronous motor, such as Figure 1-Figure 2 As shown, the motor body 100 includes a rotor and a stator. The stator is sleeved on the outer side of the rotor. The stator includes a stator core 21 and a plurality of winding coils 22. Each winding coil 22 is respectively embedded in the stator core 21, and each winding coil 22 is respectively evenly spaced along the circumference of the stator core 21, and an air gap 3 is formed between the rotor and the stator. The structure of the stator adopts the stator structure adopted by the existing motor. A rotating shaft is installed on the rotor. The mounting structure between the rotating shaft and the rotor and the mounting structure between the rotor and the stator are conventional mounting structures adopted by the existing motor, so they are not described in detail.

[0037] In the present invention, the above-mentioned rotor is an asymmetrically arranged rotor, which includes a rotor core 4 and a plurality of permanent magnets 5, each of which is respectively embedded in the rotor core 4, and each of which is sequentially arranged at intervals along the circumferential direction of the rotor core 4, and each two adjacent permanent magnets 5 are arranged in an eight-shaped shape, wherein, on the same end face of the rotor, the polarities of the magnetic poles of two adjacent permanent magnets 5 are different from each other, for example, two adjacent permanent magnets 5 correspond to permanent magnet one and permanent magnet two, respectively, and at the first end face of the rotor, the magnetic poles of permanent magnet one and permanent magnet two correspond to N and S, respectively.

[0038] The rotor core 4 is also provided with a plurality of magnetic barriers 6 and a plurality of magnetic isolation bridges 7. The distribution of each magnetic barrier 6 is as follows: each permanent magnet 5 is provided with a magnetic barrier 6 on one side of the air gap 3 close to the motor body 100, wherein a pair of two permanent magnets 5 close to each other are not provided with magnetic barriers, and the pair of permanent magnets 5 is the first permanent magnet group. Each magnetic barrier 6 is arranged at intervals along the circumference of the rotor core 4. In this embodiment, two magnetic barriers close to two permanent magnets 5 close to each other are a group of magnetic barriers, i.e., a magnetic barrier group. Two magnetic barriers 6 in each group of magnetic barriers are arranged at intervals. The length and thickness are the same, and the widths of the two magnetic barriers 6 in each group of magnetic barriers are the same. The lengths of two adjacent magnetic barrier groups are the same, but the widths of two adjacent magnetic barrier groups are different. Specifically, the two adjacent permanent magnets 5 opposite to the first permanent magnet group are the first permanent magnet group. With the first permanent magnet group as the starting point, each magnetic barrier group is arranged gradually larger along both sides. In addition, in the cross section of the rotor, the extended line between the center of the first permanent magnet group and the axis of the rotor is the symmetry line 8, and the rotor is symmetrically distributed along the symmetry line 8.

[0039] The distribution of each magnetic isolation bridge 7 is as follows: a magnetic isolation bridge 7 is provided between each permanent magnet and the air gap 3 of the above-mentioned motor body 100, and each magnetic isolation bridge 7 is respectively adjacent to the air gap 3, and each magnetic isolation bridge 7 is respectively arranged at intervals along the circumferential direction of the rotor core 4. In this embodiment, two magnetic isolation bridges respectively adjacent to two mutually close permanent magnets 5 are used as a group of magnetic isolation bridges, that is, a magnetic isolation bridge group. The lengths of the two magnetic isolation bridges 7 in each group of magnetic isolation bridge groups are the same, the thicknesses of the two magnetic isolation bridges 7 in each group of magnetic isolation bridge groups are the same, the widths of the two magnetic isolation bridges 7 in each group of magnetic isolation bridge groups are the same, the lengths of each magnetic isolation bridge in the two adjacent magnetic isolation bridge groups are the same, but the thicknesses of each magnetic isolation bridge in the two adjacent magnetic isolation bridge groups are different. To elaborate, taking the above-mentioned first permanent magnet group as the starting point, the thicknesses of each magnetic isolation bridge group are arranged to gradually decrease along both sides, and, in the cross section of the rotor, the rotor is symmetrically distributed along the symmetry line 8.

[0040] Specifically, for the convenience of description, the asymmetric structure of the above-mentioned rotor is: in the cross section of the rotor, the rotor is symmetrically arranged along the above-mentioned symmetry line 8, that is, the rotor is symmetrically arranged along the left and right sides, and the rotor is asymmetrically arranged along the upper and lower sides of the symmetry line 8, where the left and right refer to Figure 1 The orientation shown is the reference direction of the motor body 100, facing Figure 1 The left hand side is the left side, and the right hand side is the right side; thus, the motor body 100 forms an asymmetric topological structure through the asymmetric structure of the rotor, wherein the stator is a symmetric structure. It should be noted that the left and right sides mentioned here are symmetrical along the symmetry line 8, which is only for the purpose of Figure 1 The description of the orientation shown is for reference only. This embodiment is not limited to the asymmetric situation described above, and the specific situation varies depending on the orientation of the rotor.

[0041] Furthermore, the motor body 100 is a structure based on an interior permanent magnet synchronous motor, and the number of slots is an odd number of slots, for example, the motor has 8 poles and 9 slots, 10 poles and 15 slots, and 12 poles and 15 slots.

[0042] Furthermore, each of the above-mentioned permanent magnets 5 is in the shape of an elongated strip, and each of the permanent magnets 5 is respectively extended and arranged along the first end surface to the second end surface of the rotor core 4, wherein every two adjacent permanent magnets 5 are respectively in the shape of an eight-shaped opening toward the axis of the rotor core 4 or in the shape of an eight-shaped opening toward the air gap 3 of the motor body 100; in the present embodiment, each of the permanent magnets 5 adopts the permanent magnets used in the existing motor, and the embedded structure of each permanent magnet 5 is an existing conventional structure, for example, a plurality of through slots are respectively opened on the above-mentioned rotor core 4, and each through slot is respectively arranged one-to-one with each permanent magnet 5, and each permanent magnet 5 is respectively embedded in the corresponding through slot.

[0043] Furthermore, the rotor core 4 is provided with a plurality of through holes, each of which is a square hole, and both ends of each through hole extend along the end faces of the rotor core 4, respectively, and each through hole forms the magnetic barrier 6, and the length of each magnetic barrier 6 extends from the first end face to the second end face of the rotor core 4, respectively, wherein the length and thickness of each magnetic barrier 6 are the same, wherein the length refers to the value along the axial direction of the rotor core 4, and the thickness refers to the value away from the central axis direction of the rotor core 4; in this embodiment, the motor The main body 100 is illustrated by taking an example of an 8-pole 9-slot internal permanent magnet synchronous motor, wherein each magnetic barrier group takes the first permanent magnet group as a starting point, and corresponds to magnetic barrier group one, magnetic barrier group two and magnetic barrier group three in the clockwise direction, and corresponds to magnetic barrier group one, magnetic barrier group two and magnetic barrier group three in the counterclockwise direction, that is, this embodiment has two magnetic barrier groups one, two magnetic barrier groups two and two magnetic barrier groups three, the width of the magnetic barrier in the two magnetic barrier groups one is smaller than the width of the magnetic barrier 6 in the two magnetic barrier groups two, and the width of the magnetic barrier 6 in the two magnetic barrier groups two is smaller than the width of the two magnetic barriers 6 in the two magnetic barrier groups three.

[0044] Furthermore, the width and length of each magnetic isolation bridge 7 are the same, and each magnetic isolation bridge is in a strip shape. Each magnetic isolation bridge 7 is a magnetic isolation bridge formed of the same material as the rotor core 4. In this embodiment, each magnetic isolation bridge 7 is made of silicon steel material. In this embodiment, the motor body 100 is an 8-pole 9-slot built-in permanent magnet synchronous motor as an example. Each magnetic isolation bridge takes the first permanent magnet group as the starting point, and the clockwise direction corresponds to the magnetic isolation bridge group one, the magnetic isolation bridge group two and the magnetic isolation bridge group three and four, and the counterclockwise direction They correspond to magnetic isolation bridge group one, magnetic isolation bridge group two and magnetic isolation bridge group three respectively, that is, this embodiment has two magnetic isolation bridge groups one, two magnetic isolation bridge groups two, two magnetic isolation bridge groups three and one magnetic isolation bridge group four, the thickness of the two magnetic isolation bridges 7 in the two magnetic isolation bridge groups one is greater than the thickness of the two magnetic isolation bridges 7 in the two magnetic isolation bridge groups two, the thickness of the two magnetic isolation bridges 7 in the two magnetic isolation bridge groups two is greater than the thickness of the two magnetic isolation bridges 7 in the two magnetic isolation bridge groups three, and the thickness of the two magnetic isolation bridges 7 in the two magnetic isolation bridge groups three is greater than the thickness of the two magnetic isolation bridges 7 in the magnetic isolation bridge group four.

[0045] The present embodiment is a sensorless built-in permanent magnet synchronous motor, which adopts a plurality of magnetic barriers and a plurality of magnetic isolation bridges installed on an asymmetric stator. The magnetic barriers and the magnetic isolation bridges are arranged in the above-mentioned manner. The width of each magnetic barrier group is different, and the thickness of each magnetic isolation bridge group is different. In this way, the inductance on the motor body 100 exhibits mechanical periodic characteristics, so as to subsequently detect the mechanical angle of the rotor and then obtain the position of the rotor, thereby realizing that there is no need to install a position sensor on the motor body 100.

[0046] The present invention also discloses a rotor mechanical angle detection method, such as Figure 1-5 As shown, the aforementioned built-in permanent magnet synchronous motor is adopted, and the built-in permanent magnet synchronous motor is an 8-pole 9-slot motor. The specific detection method is as follows.

[0047] S1. Obtain the correspondence table: Step A1: When the motor body 100 is stopped, position the motor body 100 at four electrical angle zero points in sequence. The four electrical angle zeros divide the position of the rotor into four mechanical sectors, and the four mechanical sectors correspond to mechanical sector one, mechanical sector two, mechanical sector three and mechanical sector four, respectively.

[0048] Step A2: At each electrical angle zero, high-frequency voltage signals are injected into the AB phase, BC phase, and AC phase of the motor body 100 to measure the three current response steady-state amplitudes corresponding to each electrical angle zero, that is, the current response steady-state amplitude between the AB phases at each electrical angle zero. i AB , the steady-state amplitude of the current response between the BC phases i BC , the steady-state amplitude of the current response between AC phases i AC ; Then the measured current response steady-state amplitude corresponding to each electrical angle of zero degrees is i AB , i BC , i AC Record them respectively to obtain the current response steady-state amplitude corresponding to each mechanical sector, so as to obtain a corresponding relationship table between each mechanical sector and the current response steady-state amplitude.

[0049] S2. Determine the initial mechanical sector: Before the motor body 100 needs to be started, first position the motor body 100 to the nearest electrical angle zero point, then inject high-frequency voltage signals into the AB phase, BC phase and AC phase of the motor body 100 respectively, and measure the steady-state amplitude of the current response of the AB phase, BC phase and AC phase. i AB , i BC , i AC , and then the mechanical sector where the rotor is currently located is obtained through the corresponding relationship table obtained in the above step A2.

[0050] S3. Determine the accurate mechanical sector: After the motor body 100 is started, a conventional position sensorless control algorithm is used to detect the rotor electrical angle in real time. Each time the rotor electrical angle increases by 360°, the mechanical sector is updated by one. After the mechanical sector is updated to mechanical sector four, mechanical sector four is reset to mechanical sector one when updated again.

[0051] It should be noted that using the above-mentioned position sensorless control algorithm to detect the rotor electrical angle is a routine operation in the motor field. For example, in this embodiment, the position sensorless control algorithm can be a pulse high-frequency voltage signal injection method, but the position sensorless control algorithm can also use other conventional methods and is not limited to the above-mentioned method.

[0052] S4, obtaining the rotor mechanical angle: obtaining the rotor electrical angle and the mechanical sector where the rotor is located through step S3, and then using the mechanical angle calculation formula to obtain the rotor mechanical angle, the mechanical angle calculation formula is: , in the mechanical angle calculation formula θ m Indicates the mechanical angle, θ e represents the rotor electrical angle, S Indicates the mechanical sector, P n Represents the number of pole pairs.

[0053] It should be noted that in step A1, the number of the above-mentioned electrical angle zero degrees is set according to the basic structure of the motor body 100, that is, the number of electrical angle zero degrees is adapted to the number of pole pairs of the motor body 100. For example, if an 8-pole 9-slot motor has 4 pole pairs, then the number of electrical angle zero degrees is 4. For another example, if the number of pole pairs of the motor body 100 is 6, then there are six electrical angle zero points.

[0054] Furthermore, in the above-mentioned step S1, the rotor is manually rotated to four electrical angle zero points respectively. In detail, since the four electrical angle zero points are symmetrically distributed in space and the air gap magnetic resistance of the motor body 100 is unevenly distributed, after the rotor is rotated, it will automatically position itself toward the zero point with the smallest magnetic resistance, thereby realizing the positioning of the four electrical angle zero points.

[0055] Furthermore, the amplitude of the high-frequency voltage signal in the above-mentioned step A1 and step S2 is 100V and the frequency is 250Hz. The high-frequency voltage signal can be obtained by conventional means, such as using a DSP microcontroller to generate a control signal to drive the inverter of the motor body 100 to obtain it.

[0056] Furthermore, in step S1 and step S2, the steady-state amplitudes of the above-mentioned response currents can be acquired by using a conventional sampling method, for example, using an ADC module of a DSP microcontroller to perform current sampling.

[0057] Furthermore, the corresponding relationship table in step S1 can be formed by integrating a control system, and the control system is associated with the motor body 100. This type of control system is very common in the market, so it will not be described in detail.

[0058] Furthermore, in step S2, the motor body 100 is pre-positioned to locate the nearest zero point. In this embodiment, the pre-positioning is a conventional processing operation in the motor field, so it will not be described in detail.

[0059] Further, in step S4, the relationship between the rotor mechanical angle, the rotor electrical angle and the rotor mechanical sector is as follows: Figure 3 As shown, in Figure 3 Among them, Ⅰ, Ⅱ, Ⅲ and Ⅳ correspond to mechanical sector 1, mechanical sector 2, mechanical sector 3 and mechanical sector 4 respectively.

[0060] Furthermore, in the above step S1, due to the use of the aforementioned built-in permanent magnet motor, the inductance on the motor body 100 generates a harmonic component with the same frequency as the mechanical period of the motor body 100. The above steps can be used to obtain Figure 4 The inductance waveform shown, Figure 4 The red line represents the line inductance of the AB phase, the blue line represents the line inductance of the BC phase, and the green line represents the line inductance of the AC phase. Conventional FFT analysis is used on the inductance waveform to obtain the following: Figure 5 The harmonic components shown in FIG. 1 are harmonic components of the same frequency as the mechanical period of the motor body 100. Moreover, under the high-frequency voltage signal, the steady-state amplitude of the current response of the motor body 100 is related to the inductance of the motor body 100, that is, the formula , where U AB Indicates the line voltage between phase A and phase B, L AB Indicates the line inductance between phase A and phase B, where U BC , U AC in other words, the steady-state amplitude of the current response detected in step S1 also includes the harmonic component of the same frequency as the mechanical period of the motor body 100, and the mechanical angle information of the rotor can be obtained from the harmonic component.

[0061] A rotor mechanical angle detection method is applicable to the aforementioned built-in permanent magnet synchronous motor. A plurality of magnetic barriers and magnetic isolation bridges are introduced. The magnetic barrier widths between corresponding magnetic barrier groups are different, and the magnetic isolation bridge thicknesses between corresponding magnetic isolation bridge groups are different, so as to increase the harmonic content of the air gap magnetic density, thereby increasing the harmonic content of the inductance on the motor body 100, so that the inductance has mechanical periodic characteristics, so as to realize the detection of the rotor mechanical angle, and then obtain the rotor position information. The detection method does not need to add additional sensors to the motor body 100, reduces the spatial volume of the motor body 100, and has relatively small changes to the motor body 100. The manufacturing is relatively simple, the cost is low, and the reliability is good. In addition, the detection method is applicable to built-in permanent magnet motors with different pole pairs.

[0062] The above description is only a preferred embodiment of the present embodiment, and all equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A rotor mechanical angle detection method, characterized in that: The invention is suitable for a built-in permanent magnet synchronous motor, wherein the built-in permanent magnet synchronous motor comprises a motor body, wherein the motor body comprises a rotor, wherein the rotor comprises a rotor core and a plurality of permanent magnets embedded in the rotor core, wherein the permanent magnets are sequentially arranged at intervals along the circumference of the rotor core, and at the same end face of the rotor, the magnetic poles of every two adjacent permanent magnets are different from each other; the rotor core is provided with a plurality of magnetic barriers and magnetic isolation bridges, wherein each permanent magnet is provided with a magnetic barrier corresponding to a side close to the outer side of the rotor, wherein a pair of two permanent magnets close to each other are not provided with magnetic barriers, and each magnetic barrier is respectively arranged along the circumference of the rotor core. The core is arranged at intervals in the circumferential direction, with two magnetic barriers respectively adjacent to two permanent magnets close to each other forming a magnetic barrier group, in each group of the magnetic barriers, the width and thickness of the two magnetic barriers are respectively the same, and the widths of each magnetic barrier group are different; a magnetic isolation bridge is respectively arranged between each permanent magnet and the outer side of the rotor, and each magnetic isolation bridge is respectively arranged at intervals in the circumferential direction of the rotor core, with two magnetic isolation bridges respectively adjacent to two permanent magnets close to each other forming a magnetic isolation bridge group, in each group of the magnetic isolation bridge group, the length and thickness of the two magnetic isolation bridges are respectively the same, and the thickness of each magnetic isolation bridge group is different; the specific detection method is, S1. Obtain a corresponding relationship table: A1. When the motor body is stopped, the motor body is positioned at n electrical angle zero points in sequence, where the value of n matches the number of pole pairs of the motor body, and the n electrical angle zero points respectively divide the position of the rotor into n mechanical sectors, and each of the mechanical sectors corresponds to mechanical sector 1, mechanical sector 2, mechanical sector 3 to mechanical sector n; A2. At each electrical angle zero point, high-frequency voltage signals are injected into the AB phase, BC phase and AC phase of the motor body respectively to measure the steady-state amplitude of the current response between the AB phases. i AB , the steady-state amplitude of the current response between the BC phases i BC , the steady-state amplitude of the current response between AC phases i AC ; Then record the current response steady-state amplitude corresponding to each electrical angle zero point i AB , i BC , i AC , to obtain the current response steady-state amplitude corresponding to each of the mechanical sectors, and obtain a corresponding relationship table; S2. Determine the initial mechanical sector: before the motor body needs to be started, first position the motor body to the nearest electrical angle zero point, inject high-frequency voltage signals into the AB phase, BC phase and AC phase of the motor body, respectively, and measure the current response steady-state amplitude of the AB phase, BC phase and AC phase respectively. i AB , i BC , i AC , and then obtaining the mechanical sector where the rotor is currently located through the corresponding relationship table in step A2; S3, determining the mechanical sector: after the motor body is started, a position sensorless control algorithm is used to detect the rotor electrical angle in real time, and the mechanical sector is updated by one every time the rotor electrical angle increases by 360°. After the mechanical sector is updated to the mechanical sector n, the mechanical sector n is reset to the mechanical sector one when it is updated again; S4. Obtaining the mechanical angle of the rotor: using a mechanical angle calculation formula to obtain the mechanical angle of the rotor, the mechanical angle calculation formula is: ,in θ m is the mechanical angle, θ e is the rotor electrical angle, S For the mechanical sector, P n is the pole pair number.

2. A rotor mechanical angle detection method according to claim 1, characterized in that: The position sensorless control algorithm is a pulse high frequency voltage signal injection method.

3. A rotor mechanical angle detection method according to claim 1, characterized in that: In step A1 and step S2, the amplitude of the high-frequency voltage signal is 100V and the frequency is 250 Hz.

4. A rotor mechanical angle detection method according to claim 1, characterized in that: In the cross section of the rotor core, the two permanent magnets without the magnetic barrier are the first permanent magnet group, the extended line between the centers of the two first permanent magnet groups and the axis of the rotor core is the symmetry line, and the rotor is symmetrically arranged along the symmetry line.

5. A rotor mechanical angle detection method according to claim 4, characterized in that: Taking the first permanent magnet group as a starting point, the widths of the magnetic barrier groups are arranged to gradually increase along both sides.

6. A rotor mechanical angle detection method according to claim 5, characterized in that: The rotor core is provided with a plurality of through holes, and two ends of each through hole extend along two end surfaces of the rotor core respectively, and each through hole forms the magnetic barrier respectively.

7. A rotor mechanical angle detection method according to claim 5, characterized in that: Taking the first permanent magnet group as a starting point, the thickness of each magnetic isolation bridge group is gradually reduced along both sides.

8. A rotor mechanical angle detection method according to claim 7, characterized in that: The permanent magnets adjacent to each other are arranged in an eight-shaped pattern.

9. A rotor mechanical angle detection method according to claim 8, characterized in that: The motor body further comprises a stator, which is sleeved on the outer side of the rotor, and an air gap is arranged between the stator and the rotor, and each of the magnetic isolation bridges and each of the magnetic barriers are respectively adjacent to the air gap.

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