CN218102928U

CN218102928U - Permanent magnet synchronous motor

Info

Publication number: CN218102928U
Application number: CN202221506116.9U
Authority: CN
Inventors: 李文杰; 孙建; 周明俊; 毛刚挺
Original assignee: Hangzhou Shiteng Technology Co ltd
Current assignee: Hangzhou Shiteng Technology Co ltd
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2022-12-20
Anticipated expiration: 2032-06-15

Abstract

The embodiment of the utility model discloses permanent magnet synchronous motor, include: an outer rotor assembly; the front end cover and the rear end cover are respectively arranged at two ends of the outer rotor component and form a cavity; a stator assembly disposed within the cavity; the magnetic ring assembly is arranged on the rear end cover and can provide a sinusoidal magnetizing magnetic field; and a hall plate assembly provided with four linear hall sensors configured to sense the sinusoidal magnetizing magnetic field to output a measurement signal, a motor position angle signal having a magnetic encoder precision can be obtained, and a high-performance and high-efficiency motor control can be realized.

Description

Permanent magnet synchronous motor

Technical Field

The utility model relates to a motor control technical field, more specifically relate to a PMSM's control circuit.

Background

Along with the promotion of the plan outline of 'national fitness', more and more people begin to pay attention to physical exercise, the household exercise becomes a normal state, the running machine is a common household exercise device, is the simplest one of the household exercise devices at present, and is undoubtedly the best choice of the household fitness equipment. The design of the treadmill control system directly affects the foot feel, noise, vibration, energy consumption, user experience and other problems of the whole treadmill, most of the household treadmills on the market are limited by the volume, and the size and the power density of the motor of the treadmill control system are limited, so that the design of the treadmill control system with high performance and high efficiency is particularly important.

The existing treadmill mainly adopts a direct current brush motor control system and an alternating current asynchronous motor control system. Adopt the direct current to have brush motor advantage lies in simple structure, control system is simple, the cost is lower, but adopts the direct current to have brush motor's shortcoming to lie in: the reversing carbon brush is arranged, so that the noise of the motor is high in the working process, and the carbon brush can be abraded after long-time running, so that the noise problem is more and more serious; the AC asynchronous motor has the advantages of simple and economical maintenance, simple structure, convenient design and production, and the AC asynchronous motor has the disadvantages of: under the same power, the AC asynchronous motor has larger volume and higher energy consumption, thereby causing the household treadmill to occupy large area and not save energy.

The treadmill controlled by the two motors has large noise, large volume and high energy consumption, greatly reduces the comfort of the family user, and adopts the permanent magnet synchronous motor

Fig. 1 shows a circuit schematic diagram of a conventional sampling signal acquisition and processing circuit of a permanent magnet synchronous motor. As shown in fig. 1, the conventional sampling signal acquisition and processing circuit 100 for a permanent magnet synchronous motor includes resistors R11 to R16 and capacitors C11 to C13, detects 3 switching hall high and low levels HU1, HV1, and HW1 output by a motor 101, outputs the detected three signals HU, HV, and HW to a controller 102, and converts the signals into digital signal combinations by the controller 102 to obtain 6 position states. And carrying out interpolation processing on the discrete 6 angles through a program algorithm to obtain a linear angle for controlling a motor of a control system.

Fig. 2 shows a schematic diagram of the angle and motor current changes of a conventional sampling signal acquisition and processing circuit of a brushless motor. Where (1) is the position sector number that the sampled signals are read through the controller 102 pin level and combined into a digital signal representation. The 3 hall signals (0 or 1) are combined to combine 0-7 total 8 states, if the 3 switch type hall devices in the motor 101 are installed in a 120 ° manner, then the normal operation can show 6 states of 1-6, that is, 6 equally divided positions where the motor rotates once, as shown in fig. 2. Because 3 switching type hall devices can only show 6 positions, the resolution of three areas at each position is 60 degrees, and in order to obtain higher angular resolution, only an interpolation method can be adopted for processing, and the principle of the interpolation method is as follows:

when the motor runs close to a constant speed or the acceleration is small, the speed of the motor in the adjacent sector can be considered to be constant, and therefore the speed of the previous sector position can be used as the speed of the current sector position. Then, the duration of the current sector is calculated, i.e. the real-time displacement angle is obtained by multiplying the speed by the current time, as shown in fig. 3. Suppose that the motor is in the last position sector S _n Is of time T _p Then the speed is

If the duration of the current sector is t _c Then the current real-time position X _C Can be calculated as: x _C ＝S _n +V _P ×t _c 。

As described above, in the conventional brushless control system, since the motor position sensor is 3 switching type hall devices, which can output only 6 position states, the resolution is only 60 °. For SVPWM (Space Vector Pulse Width Modulation) Vector control systems, lower resolution means poorer motor control current and running noise. In order to solve this problem, the conventional brushless control system interpolates a discrete 60 ° angle and linearizes the angle by estimating the angle, which makes the control system output a smoother control current than the discrete angle, but under an impact load such as a treadmill, a position estimation error is also increased due to a speed fluctuation, and in a vector control system based on rotor field orientation, the presence of a position error means a maximum torque loss and an efficiency loss. The brushless control system runs under the low-speed working condition, is influenced by the installation accuracy and the induction error of the switch Hall and is based on the idea of estimation and correction, so that the traditional brushless control system cannot achieve good low-speed torque performance and foot feeling of a user in the application of the treadmill.

Compared with the switch type hall sensor for estimating the position of the rotor, the prior art also adopts a magnetic encoder applied to a permanent magnet synchronous motor control system. Although the magnetic encoder has the characteristics of high precision and high resolution, in the outer rotor motor control system, the implementation mode is complex, the cost is greatly increased, and the magnetic encoder is not suitable for the household treadmill motor control system.

In summary, there is a need to develop a high-performance and high-efficiency permanent magnet synchronous motor that outputs a motor position angle signal with magnetic encoder precision, is simple in implementation manner, has low cost, and is suitable for running of a treadmill.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model aims to provide a permanent magnet synchronous motor can obtain accurate motor position angle information, realizes high performance and efficient motor control.

According to the utility model provides a permanent magnet synchronous motor, include: an outer rotor assembly; the front end cover and the rear end cover are respectively arranged at two ends of the outer rotor component and form a cavity; a stator assembly disposed within the cavity; the magnetic ring assembly is arranged on the rear end cover and can provide a sinusoidal magnetizing magnetic field; and a hall plate assembly provided with four linear hall sensors configured to sense the sinusoidal magnetizing magnetic field to output a measurement signal.

Optionally, the four linear hall sensors are installed on the hall plate assembly in a centrosymmetric manner.

Optionally, the four linear hall sensors are disposed at an edge portion of the hall plate assembly.

Optionally, the permanent magnet synchronous motor further includes: a shield assembly disposed at a lower end of the stator assembly and coaxially aligned with the stator assembly about a rotational axis.

Optionally, a hall plate mounting groove is formed in the shielding case assembly and used for placing the hall plate assembly.

Optionally, a second gap is provided between the end face of the stator assembly and the shield assembly.

Optionally, the width of the second gap is substantially 5mm.

Optionally, the stator assembly is coaxially disposed within the outer rotor assembly.

Optionally, the outer rotor assembly is coaxially aligned with the stator assembly about the axis of rotation.

Optionally, the magnet ring assembly may be operatively coupled to the outer rotor assembly, the magnet ring assembly and the outer rotor assembly being configured to rotate as a unit about the rotational axis relative to the stator assembly.

Optionally, the four linear hall sensors are configured to generate the measurement signal according to a sinusoidal magnetizing magnetic field of the magnet ring assembly when the outer rotor assembly rotates relative to the stator assembly.

Optionally, the measurement signal is indicative of a magnetic flux density of the magnetizing field.

Optionally, the measurement signal has a shape of a sinusoidal waveform.

Optionally, the magnetic ring assembly is tightly matched with the hall plate assembly to achieve a high-precision measurement signal.

Optionally, the magnet ring assembly is configured as a closed annular ring.

Optionally, an edge surface of the closed annular ring is configured to directly face four linear hall sensors on the hall plate assembly.

Optionally, a first gap is provided between the magnetic ring assembly and the hall plate assembly.

Optionally, the wide band of the first gap is in a range of 2mm to 5mm.

Optionally, the front end cover is further provided with a first bearing seat for mounting the first bearing.

Optionally, the rear end cover is further provided with a second bearing seat for mounting a second bearing.

Optionally, the permanent magnet synchronous motor further includes a rotor position resolving circuit configured to determine a rotational position of the outer rotor assembly based on the measurement signal.

Optionally, the permanent magnet synchronous motor further comprises a drive control circuit configured to control a drive action of the permanent magnet synchronous motor based on the determined rotation position of the outer rotor assembly.

Optionally, the rotor position analyzing circuit includes: the signal processing module is configured to perform deviation correction on the measurement signal and output a sampling signal containing outer rotor position information; an analog-to-digital conversion module configured to convert the sampled signal into a digital signal; and the analysis module is configured to analyze the sampling signal based on a preset algorithm to obtain the rotation angle of the outer rotor component.

Optionally, the preset algorithm includes an arc tangent algorithm and a PLL phase-locked loop algorithm.

To sum up, the utility model provides a PMSM uses linear hall sensor to replace 3 switch type hall devices on traditional external rotor PMSM's basis, can measure continuous magnetic ring magnetic field to output continuous measuring signal, and be different from traditional switch type hall and can only acquire rough discrete angle, and linear hall sensor can acquire continuous motor position angle information, need not estimate through interpolation algorithm, does not have the angle error, measures more accurately;

furthermore, the utility model provides an use linear hall sensor to measure motor position angle to both can use two linear hall of quadrature to measure, also can use the linear hall of four central symmetry to measure.

Furthermore, four linear Hall devices installed in a central symmetry mode can output two groups of complementary measuring signals, on one hand, the influence caused by inconsistent Hall devices and inconsistent magnetizing of magnetic rings can be eliminated, on the other hand, the suppression of common mode interference under a high-current strong magnetic environment can be realized through a differential amplifying circuit, the anti-interference capability of a control system is improved,

further, the utility model discloses a design hysteresis loop is relatively fuses the compensation with the output angle of arctangent algorithm and phase-locked loop algorithm. The method has the advantages that the method has the characteristic of high real-time performance in calculating the position angle by the arc tangent algorithm, the method has the characteristics of high reliability and high anti-interference capability in calculating the position angle by the phase-locked loop algorithm, the compensation angle is output by utilizing hysteresis comparison to compensate the position angle calculated by the phase-locked loop algorithm, and the angle information with high anti-interference capability and high real-time performance can be output. And the rotating speed information for the speed closed-loop control can be directly output through a phase-locked loop algorithm.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 shows a circuit schematic diagram of a conventional sampling signal acquisition and processing circuit of a permanent magnet synchronous motor;

FIG. 2 is a schematic diagram showing the angle and motor current changes of a conventional sampling signal acquisition and processing circuit of a brushless motor;

fig. 3 shows an exploded perspective view of a permanent magnet synchronous machine according to the present invention;

figure 4 shows a schematic view of a cross section of a permanent magnet synchronous machine according to the invention;

fig. 5 shows a schematic, partially enlarged view of a permanent magnet synchronous motor according to the present invention;

fig. 6 shows a partial cross-sectional view of a permanent magnet synchronous machine according to the present invention;

fig. 7 shows a schematic structural diagram of a hall plate assembly in a permanent magnet synchronous motor according to the present invention;

FIG. 8 illustrates a waveform schematic of an output signal of the Hall plate assembly of FIG. 7;

FIG. 9 shows a circuit schematic of a signal processing circuit for two orthogonal linear Hall sensors;

fig. 10 is a schematic view showing another structure of a hall plate assembly in a permanent magnet synchronous motor according to the present invention;

FIG. 11 illustrates a waveform schematic of an output signal of the Hall plate assembly of FIG. 10;

fig. 12 shows a schematic diagram of the automatic correction of interference waveforms by four centrosymmetric linear hall sensors of the present invention;

FIG. 13 shows a circuit schematic of a signal processing circuit for four centrosymmetric linear Hall sensors;

fig. 14 shows a circuit schematic of a control circuit for a permanent magnet synchronous machine according to the present invention;

fig. 15 shows a schematic circuit diagram of a parsing module according to the invention;

FIG. 16 is a schematic diagram of the algorithm block of the phase locked loop of FIG. 15;

FIG. 17 shows a schematic diagram of the arctangent algorithm block of FIG. 15;

fig. 18 shows a circuit schematic of a motor control system according to the present invention;

fig. 19 shows a schematic diagram of the output angle and the waveform of the motor current of the motor control system according to the present invention.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.

Numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of components, are set forth in the following description in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The utility model provides a people discovers through the research, and traditional brushless control system is owing to used external rotor PMSM, fine solution the direct current have the carbon brush wearing and tearing problem of brush motor, and compare in AC asynchronous machine, and its power density is bigger, and the power demand who especially adapted this kind of compact space of domestic treadmill is used. On this application outer rotor permanent magnet synchronous motor's basis, use 3 switch type hall devices of a plurality of linear hall sensor substitution for its output has the motor position angle signal of magnetic encoder precision, can realize high performance and efficient motor control.

The utility model provides a Permanent Magnet Synchronous Motor (PMSM) 200. Permanent magnet synchronous machine 200 is a brushless motor, also known as an Electronically Commutated (EC) motor, and PMSM is a synchronous machine that uses permanent magnets instead of windings inside the rotor/rotor housing. The permanent magnet synchronous motor 200 is powered by a dc power source through an integrated inverter/switching power source, producing an alternating electrical signal to drive the poles. The alternating electrical signal comprises a bidirectional electrical current. Brushless motors offer several advantages over brushed dc motors, including high torque to weight ratios, higher torque per watt (improved efficiency), increased reliability, reduced noise, longer service life (brushless and commutator erosion), elimination of commutator ionizing sparks, and overall reduction of electromagnetic interference (EMI).

As shown in fig. 3 to 5, the permanent magnet synchronous motor 200 may include a rotation shaft 1, an outer rotor assembly 2, a stator assembly 3, a front end cover 4, a rear end cover 5, a shield can assembly 6, a hall plate assembly 7, and a magnetic ring assembly 8.

The outer rotor assembly 2 may include a rotor housing and at least one rotor magnet (not shown) connected to the rotor housing. The rotor magnet may be equivalent to at least one rotor magnetic counter-pole providing magnetic flux. In some embodiments, the rotor poles may be permanent magnets and the rotor magnetic antipodes are N and S poles. The rotor poles may be made of a magnetic material such as ferrite or bonded NdFeB. In some embodiments, the plurality of magnets may be passed. The plurality of magnets may correspond to a plurality of rotor magnetic antipodes. The plurality of rotor magnetic counter poles may be opposing magnetic poles provided in an alternating fashion (e.g., N-S-N-S). The plurality of rotor magnets may be configured to generate magnetic flux.

The stator assembly 3 may be coaxially disposed inside the outer rotor assembly 2. The outer rotor assembly 2 and the stator assembly 3 may be coaxially aligned about the rotating shaft 1. The front end cover 4 and the rear end cover 5 are respectively installed at two ends of the outer rotor component 2 to form a cavity, the stator component 3 is located in the cavity and is coaxially arranged with the outer rotor component 2, the first bearing seat 41 and the second bearing seat 51 are respectively arranged in the front end cover 4 and the rear end cover 5, and the first bearing 91 and the second bearing 92 are respectively installed in the first bearing seat 41 and the second bearing seat 51. The rotating shaft 1 is connected with the outer rotor assembly 2, the outer rotor assembly 2 is sleeved outside the stator assembly 3, and the rotating shaft 1 is supported on the first bearing 91 and the second bearing 92. The lower extreme at stator module 3 is installed to shield cover subassembly 6, and with stator module 3 around pivot 1 coaxial alignment, is equipped with hall plate mounting groove 61 on the shield cover subassembly 6, has placed hall plate subassembly 7 in the hall plate mounting groove 61, still install magnetic ring subassembly 8 on the rear end cap 5, magnetic ring subassembly 8 erection joint is at the tail end of pivot 1, magnetic ring subassembly 8 is located hall plate subassembly 7's below, and magnetic ring subassembly 8 and hall plate subassembly 7 compact fit can reach the feedback signal of high accuracy, and more accurate judgement rotor position improves control accuracy.

The permanent magnet synchronous machine may also include a plurality of windings (not shown) surrounding the stator. In the example shown in fig. 3, the stator assembly 3 may be a radial winding stator. In a radial winding stator, each stator pole extends radially from the circumference of the stator hub to form a radially extending portion and expands tangentially at the end of the radially extending portion to form a tangentially extending portion. In some alternative embodiments, the stator assembly 3 may be an axial winding stator. In an axial winding stator, each stator pole extends transversely around the circumference of the stator hub in a direction orthogonal to the radial direction.

When current is passed through the windings, the plurality of windings and the stator are converted into electromagnets (stator poles). The current may be, for example, a three-phase current. The electronic controller may be configured to generate a sinusoidal current for energizing the windings on the stator to drive the outer rotor assembly 2. The electronic controller may be configured to direct rotation of the outer rotor assembly 2. The electronic controller is configured to determine the orientation/position of the rotor relative to the stator by measuring the rotational position of the rotor using one or more position sensors.

Permanent magnet synchronous motors may be powered by a Direct Current (DC) power source through a switching power supply. The switching power supply may be an integrated inverter. The switching power supply may be configured to generate bidirectional direct current. In some cases, the bidirectional direct current has a sinusoidal waveform. Alternatively, the bidirectional direct current has a square waveform. Alternatively, the bidirectional direct current may have a sawtooth waveform. Any type of waveform of bidirectional direct current may be considered.

Fig. 6 shows a partial cross-sectional view of a permanent magnet synchronous machine according to the invention. As previously described, the shield assembly 6 is mounted to the lower end of the stator assembly 3 and is coaxially aligned with the stator assembly 3 about the axis of rotation 1. In some embodiments, the shield assembly 6 is spaced from the end face of the stator assembly 3. The gap may be an air gap. In some embodiments, the width of the gap ranges from about 5mm. Alternatively, the width of the gap may be less than 5mm, or the width of the gap may be greater than 5mm.

In some embodiments, the magnet ring assembly 8 may be a closed annular ring. The edge surface of the closed annular ring may be configured to directly face the at least two linear hall sensors on the hall-plate assembly 7. Illustratively, a certain gap is also maintained between the magnet ring assembly 8 and the hall plate assembly 7. In some embodiments, the gap has a width in the range of about 2mm to about 5mm.

In fig. 6, the outer rotor assembly 2 may be configured to rotate about the rotation shaft 1 relative to the stator assembly 3. The outer rotor assembly 2 may include a plurality of rotor magnets disposed on an inner portion of the rotor case such that the rotor magnets sequentially face the plurality of stator magnets as the rotor case and the rotor magnets rotate about the rotation axis. The rotor housing may rotate at an angular velocity ω. The angular velocity ω can be measured by at least two linear hall sensors. When the motor works, the Hall plate assembly 7 is fixed, the outer rotor assembly 2 drives the magnetic ring assembly 8 to rotate together, and the magnetic ring assembly 8 has a sinusoidal magnetizing magnetic field, so that at least two linear Hall sensors on the Hall plate assembly 7 can sense a sinusoidally-changing magnetic field due to the characteristics of the linear Hall sensors, and then sinusoidal waveform measuring signals are output.

In the traditional scheme, a position sensor is directly arranged in a strong magnetic environment of a permanent magnet synchronous motor, along with the change of the size of a magnetic field, the obtained magnetic pole position also has deviation, and the position sensor is easily interfered by strong magnetism and even causes the damage of an electronic device. This application adopts external magnetic ring subassembly 8's mode to keep apart PMSM main field and position detection magnetic field physics, and the magnetic field produces harmful effects to position sensor when avoiding PMSM to have the heavy current, effectively improves position detection's precision, interference immunity and stability.

In addition, in an application scenario where the size of the permanent magnet synchronous motor is limited (for example, the motor is limited in length and needs to be made short), the hall plate assembly 7 and the magnetic ring assembly 8 need to be close to the main magnetic field of the permanent magnet synchronous motor, and in a high-current and high-magnetic environment, the hall plate assembly and the magnetic ring assembly may be interfered, so that the detection accuracy and stability are reduced. This application realizes radial magnetic conduction through shield cover subassembly 6, the axial separates the magnetism, permanent magnet synchronous machine main field vortex reaches the junction to shield cover subassembly 6 and pivot 1 along with stator module 3's pivot 1 promptly, then along the radial conduction of shield cover subassembly 6, the axial radiation in permanent magnet synchronous machine magnetic field space is sheltered from by shield cover subassembly 6 this moment, reduce its intensity of outside radiation greatly, reach the effect of magnetic field shielding, in order to restrain the influence of permanent magnet synchronous machine main field to hall plate subassembly 7 and magnetic ring subassembly 8. Therefore, the shielding case assembly 6 can also realize compact installation of the hall plate assembly 7 and the magnetic ring assembly 8, thereby realizing the miniaturization design of the permanent magnet synchronous motor.

Fig. 7 shows a schematic structural diagram of a hall plate assembly in a permanent magnet synchronous motor according to the present invention. As shown in fig. 7, the hall plate assembly 71 may include at least two position sensors. The position sensor may be configured to detect a position of the rotor magnet. The position sensor may be a magnetic field sensor. The position of the rotor magnets may be indicative of the position of the outer rotor assembly 2. The position sensor may be configured to measure a magnetic flux density of the magnetic field. The position sensor may have a linear response to the magnetic flux density of the measured magnetic field. The output voltage of the position sensor may vary linearly with the magnetic flux density of the measured magnetic field. Further, when the outer rotor assembly 2 rotates relative to the stator assembly 3, the output voltage of the position sensor may vary in response to a change in the magnetic field.

The at least two position sensors may be configured to detect the rotational position of the rotor magnetic poles based on the measured magnetic field when the outer rotor assembly 2 rotates relative to the stator assembly 3. The position sensor may be configured to generate a measurement signal indicative of a magnetic flux density of the magnetic field. In some embodiments, the measurement signal may have a shape of a substantially sinusoidal waveform.

As previously described, the rotor magnet may be operably coupled to the rotor housing. Accordingly, the rotational position of the rotor may be correlated with the rotational position of the rotor poles. The rotational position of the rotor may be determined from the rotational positions of the rotor poles and may be determined based on the measured magnetic field. The electronic controller may be configured to control a driving action of the permanent magnet synchronous motor based on the determined rotational position of the rotor.

In some embodiments, the position sensor may be a linear magnetic field sensor. For example, the sensor may be a linear hall sensor. Hall effect sensors are solid state magnetic sensor devices and can be used to sense position, velocity, and/or directional movement. Advantages of hall effect sensors include contactless wear-free operation, low maintenance, robust design, and low sensitivity to vibration, dust, and moisture due to its robust packaging. When the position sensor is selected from a linear Hall sensor, a continuous magnetic ring magnetic field can be measured, compared with the traditional switch Hall, the continuous magnetic ring magnetic field can directly detect the continuous motor position angle and is used for motor control, the traditional switch Hall can only obtain rough discrete angles, the continuous angles need to be estimated, errors exist in the angles, and the control on the permanent magnet synchronous motor is not facilitated.

A hall effect sensor is a sensor that changes its output voltage in response to a magnetic field. The magnetic field is induced by the hall plate and a "hall" voltage proportional to the induced magnetic flux is generated across the biased hall plate. The hall voltage is a potential difference that depends on the magnitude and direction of the magnetic field and the current from the power supply. The hall effect sensor operates as an analog sensor and returns an output voltage directly. With a known magnetic field, the distance from the pole of the magnetic field to the hall plate can be determined. The hall effect sensor can produce a linear output. The output signal of the linear analog hall effect sensor can be obtained directly from the output of the operational amplifier, with the output voltage being proportional to the magnetic field passing through the hall effect sensor.

In the example shown in fig. 7, 2 linear hall sensors 711 to 712 are provided on the hall plate assembly 71. Illustratively, the linear hall sensors 711-712 are mounted in an "orthogonal" manner on the hall plate assembly 71. In some embodiments, the linear hall sensors 711 to 712 are disposed at an edge portion of the hall plate assembly 71. In which the linear hall sensor 711 outputs one set of measurement signals (i.e., sine signals) and the linear hall sensor 712 outputs another set of measurement signals (i.e., cosine signals).

FIG. 8 illustrates a waveform schematic of an output signal of the Hall plate assembly of FIG. 7. In some embodiments, the sinusoidal magnetic field induced by the hall plate assembly is in a multiple periodic relationship with the permanent magnetic field of the outer rotor assembly of the motor. For example, the magnetic ring has 2 magnetic poles, and if the outer rotor assembly 2 has 8 magnetic poles, the conversion period of the sinusoidal magnetic field of the measurement signal is 4 times that of the outer rotor permanent magnetic field. At the moment, the linear Hall sensor on the Hall plate assembly outputs a sinusoidal voltage signal related to the phase of the permanent magnetic field, namely when the motor runs for a sinusoidal period, the linear Hall sensor runs for 1/4 of the sinusoidal period, and the angle of the motor is 4 times of the output angle of the linear Hall sensor. Since the 2 linear hall sensors of the present embodiment are installed in an orthogonal manner, when the magnetic ring assembly rotates clockwise following the outer rotor assembly, the orthogonal 2

linear hall sensors

711 and 712 output sine voltage signals and cosine voltage signals, respectively, as shown in fig. 7.

Fig. 9 shows a circuit schematic of a signal processing circuit for two orthogonal linear hall sensors. This exampleThe signal processing circuit 300 of (1) comprises a first signal processing module 310 and a second signal processing module 320. The input end of the first signal processing module 310 is used for receiving the sinusoidal voltage signal V output by the motor 301 _SIN And outputs the obtained sampling signal Vs1 to the ADC port ADC1 of the controller 302 for signal analysis. The input end of the second signal processing module 320 is used for receiving the cosine voltage signal V output by the motor 301 _COS And converts the sampling signal into a sampling signal Vs2, and outputs the sampling signal Vs2 to the ADC port ADC2 of the controller 302 for signal analysis.

Illustratively, the first signal processing module 310 includes a differential amplifying unit 311 and a low-pass filtering unit 312. The differential amplification unit 311 includes an operational amplifier U1A, resistors R21 and R22, and capacitors C21 and C22. The first end of the resistor R21 is connected with a measuring signal output port of the motor 301, the second end of the resistor R21 is connected with a non-inverting input end of the operational amplifier U1A, the resistor R22 and the capacitor C22 are connected in parallel between an inverting input end and an output end of the operational amplifier U1A, a power supply end of the operational amplifier U1A is connected between a power supply voltage VDD and the ground, the first end of the capacitor C21 is connected with a positive power supply end of the operational amplifier U1A, the second end of the capacitor C21 is connected with the ground, and the output end of the operational amplifier U1A is used for outputting a first voltage signal Vo1. The low-pass filtering unit 312 includes a resistor R23 and a capacitor C23, a first end of the resistor R23 is connected to the output end of the operational amplifier U1A, a second end of the resistor R23 is connected to the first end of the capacitor C23, a second end of the capacitor C23 is grounded, and an intermediate node between the resistor R23 and the capacitor C23 is connected to the port ADC1 of the controller 302. In the circuit, an operational amplifier U1A works in a deep negative feedback state, and Vo1= V can be obtained according to the 'virtual short' and 'virtual break' characteristics of the operational amplifier _SIN The first voltage signal Vo1 processed and obtained by the differential amplifying unit 311 is subjected to first-order low-pass filtering formed by a resistor R23 and a capacitor C23 to obtain a sampling signal Vs1.

Likewise, the second signal processing module 320 includes a differential amplifying unit 321 and a low pass filtering unit 322. The differential amplifying unit 321 includes an operational amplifier U2A, resistors R24 and R25, and capacitors C24 and C25. A first end of the resistor R24 is connected with a measuring signal output port of the motor 301, a second end is connected with a non-inverting input end of the operational amplifier U2A, and the resistorR25 and capacitor C25 are connected in parallel between the inverting input terminal and the output terminal of operational amplifier U1A, the power supply terminal of operational amplifier U2A is connected between power supply voltage VDD and ground, the first terminal of capacitor C24 is connected with the positive power supply terminal of operational amplifier U2A, the second terminal is grounded, and the output terminal of operational amplifier U2A is used for outputting second voltage signal Vo2. The low-pass filtering unit 322 includes a resistor R26 and a capacitor C26, a first end of the resistor R26 is connected to the output end of the operational amplifier U2A, a second end of the resistor R26 is connected to the first end of the capacitor C26, a second end of the capacitor C26 is grounded, and an intermediate node between the resistor R26 and the capacitor C26 is connected to the port ADC2 of the controller 302. In the circuit, an operational amplifier U2A works in a deep negative feedback state, and Vo2= V can be obtained according to the 'virtual short' and 'virtual break' characteristics of the operational amplifier _COS The second voltage signal Vo2 processed by the differential amplifying unit 321 is subjected to first-order low-pass filtering by a resistor R26 and a capacitor C26 to obtain a sampling signal Vs2.

Fig. 10 shows another schematic structural diagram of a hall plate assembly in a permanent magnet synchronous motor according to the present invention. In the example shown in fig. 10, 4 linear hall sensors 721 to 724 are provided on the hall-plate assembly 72. Illustratively, the linear Hall sensors 721-724 are mounted in a "centrosymmetric" manner on the Hall plate assembly 72. In some embodiments, the linear Hall sensors 721-724 are disposed at an edge portion of the Hall plate assembly 72. Among them, the

linear hall sensors

721 and 723 output one set of measurement signals, and the

linear hall sensors

722 and 724 output the other set of measurement signals.

FIG. 11 illustrates a waveform schematic of an output signal of the Hall plate assembly of FIG. 10. As mentioned above, the sinusoidal magnetic field induced by the Hall plate assembly and the permanent magnetic field of the outer rotor assembly of the motor are in a certain multiple period relationship. Because the at least two linear hall sensors of the present embodiment are installed in a centrosymmetric manner (i.e., the hall sensors are perpendicular to each other), the symmetrically distributed

linear hall sensors

721 and 723 will output one set of complementary sine signals, and the symmetrically distributed

linear hall sensors

722 and 724 will output another set of complementary cosine signals. When the magnet ring assembly follows the outer rotor assembly to rotate clockwise, the hall plate assembly will output the measurement signal waveform shown in fig. 10.

Fig. 12 shows the schematic diagram of the present invention for automatically correcting interference waveforms by four centrosymmetric linear hall sensors, in a feasible embodiment, the same group of complementary signals can be subjected to common mode interference suppression through the signal processing module (including the differential amplifying circuit), when the input signal is interfered by the outside, the two complementary signals will be interfered, and after the two signals are input to the differential amplifying circuit, the interference signal will be cancelled. In addition, when the magnetic pole magnetizing consistency of the magnetic ring assembly 8 is poor, or the electrical error of the linear hall sensors is large, the linear hall sensors which are symmetrically distributed can eliminate the original error to a certain extent, and when the fluctuation amplitudes of the two groups of differential signals are the same, the errors can be automatically corrected, so that the four linear hall sensors which are centrally and symmetrically arranged have better anti-interference performance, compatibility and stability under the high-current strong-magnetic environment.

Fig. 13 shows a circuit schematic of a signal processing circuit for four centrosymmetric linear hall sensors. The signal processing circuit 400 of the present embodiment includes a first signal processing module 410 and a second signal processing module 420. Wherein the input terminal of the first signal processing module 410 is used for receiving a set of complementary sinusoidal voltage signals V output by the motor 401 _SIN+ And V _SIN- And outputs the obtained sampling signal Vs1 to the ADC port ADC1 of the controller 402 for signal analysis. The input end of the second signal processing module 420 is used for receiving another set of complementary cosine voltage signals V output by the motor 401 _COS+ And V _COS- And converts the sampling signal into a sampling signal Vs2, and outputs the sampling signal Vs2 to the ADC port ADC2 of the controller 402 for signal analysis.

Illustratively, the first signal processing module 410 includes a differential amplifying unit 411 and a low-pass filtering unit 412. The difference between the differential amplification unit 411 and the differential amplification unit 311 of the first embodiment is that resistors R27 and R28 and a capacitor C27 are further included. Wherein, the first end of the resistor R21 and the sine voltage signal V of the motor 401 _SIN+ Is connected to the non-inverting input of the operational amplifier U1A, and a second terminal of the resistor R27Sinusoidal voltage signal V of first terminal and motor 401 _SIN- Is connected to the inverting input of the operational amplifier U1A, and the resistor R28 and the capacitor C27 are connected in parallel between the reference voltage VREF and the non-inverting input of the operational amplifier U1A. Other elements and connection relationships of the differential amplifying unit 411 and those of the low-pass filtering unit 412 are identical to those of the differential amplifying unit 311 and the low-pass filtering unit 312 in the first embodiment, and are not described again. Similarly, the operational amplifier U1A of the present embodiment operates in a deep negative feedback state, and according to the "virtual short" and "virtual disconnection" characteristics of the operational amplifier, the first voltage signal Vo1= V processed by the differential amplifying unit 411 can be obtained _SIN+ The voltage signal passes through the low-pass filtering unit 412 to obtain a sampling signal Vs1, and is output to the port ADC1 of the controller 402.

The second signal processing module 420 includes a differential amplifying unit 421 and a low pass filtering unit 422. The difference between the differential amplifying unit 421 and the differential amplifying unit 321 of the first embodiment is that resistors R29 and R30 and a capacitor C28 are further included. Wherein, the first end of the resistor R24 and the cosine voltage signal V of the motor 401 _COS+ Is connected to the positive input terminal of the operational amplifier U2A, and the first terminal of the resistor R29 is connected to the cosine voltage signal V of the motor 401 _COS- Is connected to the inverting input of the operational amplifier U2A, and the resistor R30 and the capacitor C28 are connected in parallel between the reference voltage VREF and the non-inverting input of the operational amplifier U2A. Other elements and connection relationships of the differential amplifying unit 421 and those of the low-pass filtering unit 422 are identical to those of the differential amplifying unit 321 and the low-pass filtering unit 322 in the first embodiment, and are not described herein again. Similarly, the operational amplifier U2A of this embodiment operates in a deep negative feedback state, and according to the "virtual short" and "virtual disconnection" characteristics of the operational amplifier, the second voltage signal Vo2= V obtained after being processed by the differential amplifying unit 421 can be obtained _COS+ The voltage signal passes through the low-pass filtering unit 422 to obtain a sampling signal Vs2, and is output to the port ADC2 of the controller 402.

Fig. 14 shows a circuit schematic of a control circuit for a permanent magnet synchronous machine according to the invention. The control circuit 500 is configured to position the outer rotor of the permanent magnet synchronous motor in accordance with the received measurement signal and to control the driving action of the motor on the basis of the determined rotational position of said outer rotor. As shown in fig. 14, the control circuit 500 includes a signal processing module 510, an analog-to-digital conversion module 520, a resolution module 530, and a driving control module 540. The signal processing circuit 510 may be implemented by the example shown in fig. 8 or fig. 11, for example, based on the number of linear hall sensors at the motor end being 2 or 4. In this embodiment, taking the number of the linear hall sensors at the motor end as 4 as an example, when the outer rotor of the motor rotates, the motor end outputs 4 paths of measurement signals (such as 2 paths of sine signals and 2 paths of cosine signals shown in fig. 10) in real time, the signal processing module 510 is configured to perform offset correction on the measurement signals and output sampling signals (the sampling signals include sine signals and cosine signals) containing position information of the outer rotor, the analog-to-digital conversion module 520 is configured to convert orthogonal sine signals and cosine signals into digital signals, and the analysis module 530 is configured to analyze the digital signals through an arc tangent algorithm and a PLL phase-locked loop algorithm, so as to obtain the position/angle of the outer rotor of the motor. The drive control module 540 is configured to provide control signals to the motor based on the determined angle information and rotational speed information of the outer rotor to control the driving action of the permanent magnet synchronous motor.

The utility model discloses an in the embodiment, after using linear hall sensor to obtain sine and cosine signal, can obtain the digital magnitude of voltage of a definite number through AD converting circuit (analog-to-digital conversion circuit). That is, the first digital signal and the second digital signal are obtained by a/D converting the first set of measurement signals or the second set of measurement signals. The digital voltage value at this time has a certain relationship with the measurement position of the position sensor, but is not the measurement angle value of the position sensor, and it is necessary to perform angle analysis.

Fig. 15 shows a schematic circuit diagram of a parsing module according to the present invention. As shown in fig. 15, the parsing module 530 of the present embodiment includes a phase-locked loop algorithm module 531, an arc tangent algorithm module 532, a hysteresis comparison module 533, a combining module 534, and a summing module 535.

The phase-locked loop algorithm module 531 is configured to receive the first digital signal (sin) and the second digital signal (cos), and calculate a first angle value PLL _ Theta and rotation speed information Omega according to the first digital signal and the second digital signal through a phase-locked loop function.

The arctangent algorithm module 532 is configured to receive the first digital signal and the second digital signal and to calculate a second angle value ATAN _ Theta by means of an arctangent function from the received signals.

The hysteresis comparing module 533 is configured to receive the first angle value PLL _ Theta and the second angle value ATAN _ Theta, and calculate a first compensation angle ATAN _ Theta _ Fusion and a second compensation angle PLL _ Theta _ Fusion based on the first angle value PLL _ Theta and the second angle value ATAN _ Theta. The first compensation angle ATAN _ Theta _ Fusion is an angle deviation used in the current comparison, and the second compensation angle PLL _ Theta _ Fusion is an angle deviation used in the previous comparison.

Specifically, the hysteresis comparing module 533 includes a difference unit 5331, a modulus unit 5332, a condition determining unit 5333, a first condition action unit 5334, and a second condition unit 5335. The difference unit 5331 is configured to difference the first angle value PLL _ Theta and the second angle value ATAN _ Theta to obtain an angle deviation therebetween. The modulus unit 5332 is configured to obtain an absolute value of the angle deviation value. The condition determination unit 5333 is configured to compare the absolute value of the angle deviation value with a system control threshold (e.g., 0.1). When the absolute value of the angle deviation is smaller than the system control threshold, the first conditional action unit 5334 is controlled to output a first compensation angle ATAN _ Theta _ Fusion; and controls the second conditional action unit 5335 to output the second compensation angle PLL _ Theta _ Fusion when the absolute value of the angle deviation is greater than the system control threshold.

The merging module 534 is a path selection module for providing one of the first compensation angle ATAN _ Theta _ Fusion and the second compensation angle PLL _ Theta _ Fusion to the summing module 535, and the summing module 535 superimposes the obtained angle deviation value with the first angle value PLL _ Theta to output final angle information Theta.

Fig. 16 shows a schematic diagram of the pll algorithm block of fig. 15. The phase-locked loop algorithm of the present embodiment is constructed by the following formula: sin (theta-theta) ^* )＝sinθ×cosθ ^* -cosθ× sinθ ^* (in this embodiment, the letter is added to indicate the observed value, and not the actual value). The principle diagram shown in fig. 14 can be obtained by constructing the PI regulator according to the above formula. As shown in FIG. 16, given an angle θ ^* Transformed into sin θ by

transform units

5320 and 5321 ^* And cos θ ^* The multiplier 5311 calculates the sine signal sin θ of the actual angle and the cosine signal cos θ of the given angle ^* Product sin theta x cos theta ^* The multiplier 5312 calculates the cosine signal cos θ of the actual angle and the sine signal sin θ of the given angle ^* The product of cos θ × sin θ ^* The difference module 5313 performs a difference on the two products to obtain a difference value sin θ × cos θ ^* -cosθ×sinθ ^* The multiplier 5314 obtains the product of the difference and the coefficient K1, and performs PI adjustment by the integrator 5315 to finally obtain the rotation speed information Omega. Meanwhile, the integrator 5316 integrates the output of the integrator 5315 again, the multiplier 5317 obtains the product between the output of the integrator 5315 and the coefficient K2, the summing module 5318 superimposes the outputs of the multiplier 5317 and the integrator 5316 together, and the remainder is obtained through a remainder unit 5319, so that the first angle value PLL _ Theta is finally obtained. In the present embodiment, the PI regulator is constructed such that

At this time, the angle theta is given ^* Following the actual angle theta, i.e.

The front stage PI regulator outputs rotation speed information Omega, and the rear stage PI regulator outputs a first angle value PLL _ Theta.

FIG. 17 shows a schematic diagram of the arctangent algorithm block of FIG. 15. Of the present embodimentThe arctan algorithm is constructed by the following equation:

as shown in fig. 17, the first digital signal (sin) and the second digital signal (cos) are provided to the function calculation module 5322, and the angle is directly calculated by the arctan function, but the angle range is

The angle range is adjusted to 0-2 pi by the summation module 5323, and finally a second angle value ATAN _ Theta is obtained.

In this embodiment, the phase-locked loop algorithm module and the arc tangent algorithm module work simultaneously, because the arc tangent algorithm module directly performs digital operation on the digital signal acquired by the sensor to obtain the angle, although the real-time performance is high, the anti-interference capability is poor, only angle information can be obtained, and the rotation speed information cannot be obtained. The phase-locked loop algorithm module can simultaneously output angle information and rotating speed information, the principle is equivalent to that of a PI (proportional-integral) regulator, and the output of the PI regulator is smooth and lagged in filtering, so that the angle information obtained by calculation is delayed. In the embodiment, the hysteresis comparison module is designed to perform fusion compensation on the two algorithm angles, the angle calculated by the phase-locked loop is compared with the angle calculated by the arc tangent, and a deviation threshold value is set. When the deviation between the two is smaller than the deviation threshold value, the current angle deviation is compensated to the angle output by the phase-locked loop, and if the deviation between the two is larger than the deviation threshold value, the deviation obtained by the last calculation is compensated to the angle output by the phase-locked loop. Through a fusion algorithm, the position analysis module can output angle information with strong anti-interference capability and high real-time performance, and can directly output rotating speed information for speed closed-loop control.

Fig. 18 shows a circuit schematic of a motor control system according to the present invention. As shown in fig. 18, the motor control system 600 includes a motor 610, an inverter circuit 620, a position resolver circuit 630, a drive control circuit 640, a current sampling circuit 650, and a control panel 660.

Wherein, motor 610 for example through the utility model discloses PMSM 200 that above-mentioned embodiment provided realizes, and it uses the linear hall sensor of a plurality of to replace switch-type hall device, when the magnetic ring subassembly followed outer rotor assembly clockwise turning, the measuring signal of sine and cosine can be exported to the linear hall sensor of a plurality of.

The location resolution circuit 630 may include a signal processing module 510, an analog-to-digital conversion module 520, and a resolution module 530. When the outer rotor of the motor rotates, the motor 610 outputs a plurality of paths of measurement signals in real time, the signal processing module 510 performs deviation correction on the measurement signals and outputs sampling signals containing position information of the outer rotor, and the analog-to-digital conversion module 520 converts the sampling signals into digital signals. The utility model discloses an in the embodiment, after using linear hall sensor to obtain sine, cosine signal, can obtain the digital voltage value of a definite number through analog-to-digital conversion module 520. That is, the first digital signal and the second digital signal are obtained by a/D converting the first set of measurement signals or the second set of measurement signals. The analyzing module 530 is configured to analyze the first digital signal and the second digital signal obtained by the conversion of the analog-to-digital conversion module 520 through an arc tangent algorithm and a PLL phase-locked loop algorithm, and finally obtain the angle and the rotation speed information of the outer rotor. The signal processing module 510, the analog-to-digital conversion module 520, and the analysis module 530 are specifically described in the above embodiments, and the angle information with strong anti-interference capability and high real-time performance is output by performing angle fusion compensation on the arc tangent algorithm and the phase-locked loop algorithm through hysteresis comparison, which is not described herein again.

The current sampling circuit 650 is used to detect the three-phase currents Ia, ib, and Ic output by the motor 610.

The driving control circuit 640 is configured to generate control signals according to the angle/rotation speed information output by the position analyzing circuit 630 and the three-phase current output by the current sampling circuit 650, control the output voltage of the inverter circuit 620, and finally regulate the current of the motor 610. Specifically, the driving control circuit 640 includes a coordinate transformation module 6401, PI adjustment modules 6403-6405, difference modules 6406-6408, a Park inverse transformation module 6409, and an SVPWM (Space Vector Pulse Width Modulation) module 6410.

The coordinate transformation module 6401 may include Clark transformation and Park transformation, where the Clark transformation is used to output two-phase stator currents I α and I β in the two-phase stationary rectangular coordinate system α - β after the three-phase currents Ia, ib, and Ic output by the current sampling circuit 650 are subjected to Clark transformation. The Park transformation process is used for outputting two-phase stator currents I alpha and I beta output by Clark transformation and angle information theta output by the position analysis circuit 630 through Park transformation and then outputting two-phase currents Id and Iq under a two-phase synchronous rotating coordinate system d-q.

The difference module 6406 is configured to perform a difference operation between the rotation speed information output by the control panel 660 and the rotation speed information Omega output by the position analyzing circuit 640.

The PI regulation module 6403 is configured to output the q-axis reference current Iq after the difference value compared by the difference module 6406 is subjected to PI regulation ^* 。

Differencing module 6407 is configured to sum the q-axis reference current Iq output by PI regulation module 6403 ^* And performing difference operation with the two-phase current Iq output by the Park conversion module 6402.

The PI regulation module 6404 is configured to output the q-axis reference voltage Vq after the difference compared by the difference module 6407 is PI-regulated.

The difference module 6408 is configured to compare the d-axis reference current Id ^* And performing difference operation with the two-phase current Id output by the Park conversion module 6402.

The PI regulation module 6405 is configured to output the d-axis reference voltage Vd after the difference compared by the difference module 6408 is PI regulated.

The Park inverse transformation module 6409 is configured to output the q-axis reference voltage Vq output by the PI regulation module 6404 and the d-axis reference voltage Vd output by the PI regulation module 6405 through Park inverse transformation to output two-phase control voltages U α and U β in a two-phase stationary rectangular coordinate system α - β.

The SVPWM module 6410 is configured to space-vector pulse width modulate the two-phase control voltages U α and U β, and output a PWM waveform to the inverter circuit 620, and the inverter circuit 620 outputs three-phase voltages Ua, ub, and Uc to the motor 610, thereby controlling the motor 610.

Fig. 19 shows a schematic diagram of the output angle and the waveform of the motor current of the motor control system according to the present invention. As shown in fig. 19, the motor control system 600 of the present embodiment has the advantages of high real-time motor angle analysis, low delay and smooth output, and can output smooth motor current, so that the torque waveform is small during the motor operation process, which is reflected in that the treadmill system has smooth feel and small speed fluctuation.

To sum up, the utility model provides a PMSM uses 4 symmetric distribution's linear hall sensor to replace 3 switch type hall devices on traditional external rotor PMSM's basis for its output has the motor position angle signal of magnetic encoder precision, can realize high performance and efficient machine control.

Furthermore, the utility model provides an use linear hall sensor to measure motor position angle to both can use the two linear hall of quadrature to measure, also can use the linear hall of four centrosymmetries to measure.

further, the utility model discloses a design hysteresis loop is relatively fused the compensation with the output angle of arctangent algorithm and phase-locked loop algorithm. The method has the advantages that the position angle calculated by the arc tangent algorithm has the characteristic of high real-time performance, the position angle calculated by the phase-locked loop algorithm has the characteristics of high reliability and strong anti-interference capability, and the compensation angle is output by utilizing hysteresis loop comparison to compensate the position angle calculated by the phase-locked loop algorithm, so that the angle information with strong anti-interference capability and high real-time performance can be output. And the rotating speed information for the speed closed-loop control can be directly output through a phase-locked loop algorithm.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A permanent magnet synchronous motor, comprising:

an outer rotor assembly;

the front end cover and the rear end cover are respectively arranged at two ends of the outer rotor component and form a cavity;

a stator assembly disposed within the cavity;

the magnetic ring assembly is arranged on the rear end cover and can provide a sinusoidal magnetizing magnetic field; and

a Hall plate assembly provided with four linear Hall sensors configured to sense the sinusoidal magnetizing magnetic field to output a measurement signal.

2. The permanent magnet synchronous motor of claim 1, wherein the four linear hall sensors are mounted on the hall plate assembly in a centrosymmetric manner.

3. The permanent magnet synchronous motor of claim 1, wherein the four linear hall sensors are disposed at an edge portion of the hall plate assembly.

4. The permanent magnet synchronous motor according to claim 1, further comprising:

a shield assembly disposed at a lower end of the stator assembly and coaxially aligned with the stator assembly about a rotational axis.

5. The PMSM of claim 4, wherein the shield assembly is provided with a Hall plate mounting slot for receiving the Hall plate assembly.

6. The permanent magnet synchronous motor of claim 4, wherein a second gap is provided between the shield assembly and an end face of the stator assembly.

7. A permanent magnet synchronous machine according to claim 6, characterized in that the width of the second gap is substantially 5mm.

8. The permanent magnet synchronous motor of claim 1, wherein the stator assembly is coaxially disposed within the outer rotor assembly.

9. The permanent magnet synchronous motor of claim 1, wherein the outer rotor assembly is coaxially aligned with the stator assembly about an axis of rotation.

10. The permanent magnet synchronous motor of claim 9, wherein the magnet ring assembly is operably coupled to the outer rotor assembly, the magnet ring assembly and the outer rotor assembly configured to rotate as a unit about the shaft relative to the stator assembly.

11. The permanent magnet synchronous motor of claim 10, wherein the four linear hall sensors are configured to generate the measurement signal as a function of a sinusoidal magnetizing magnetic field of the magnet ring assembly as the outer rotor assembly rotates relative to the stator assembly.

12. The permanent magnet synchronous machine of claim 1, wherein the measurement signal is indicative of a flux density of the magnetizing field.

13. A permanent magnet synchronous machine according to claim 1, characterized in that the measuring signal has the shape of a sine wave.

14. The permanent magnet synchronous motor of claim 1, wherein the magnet ring assembly is a close fit with the hall plate assembly to achieve a high accuracy measurement signal.

15. The permanent magnet synchronous motor of claim 1, wherein the magnet ring assembly is configured as a closed annular ring.

16. The permanent magnet synchronous motor of claim 15, wherein an edge surface of the closed annular ring is configured to directly face four linear hall sensors on the hall plate assembly.

17. The permanent magnet synchronous motor of claim 1, wherein the magnet ring assembly has a first gap with the hall plate assembly.

18. The permanent magnet synchronous motor of claim 17, wherein the wide band of the first gap ranges from 2mm to 5mm.

19. The permanent magnet synchronous motor of claim 1, wherein the front end housing is further provided with a first bearing seat for mounting a first bearing.

20. The permanent magnet synchronous motor of claim 1, wherein the rear end cap is further provided with a second bearing seat for mounting a second bearing.