WO2017063244A1 - 一种永磁电机 - Google Patents

一种永磁电机 Download PDF

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Publication number
WO2017063244A1
WO2017063244A1 PCT/CN2015/094318 CN2015094318W WO2017063244A1 WO 2017063244 A1 WO2017063244 A1 WO 2017063244A1 CN 2015094318 W CN2015094318 W CN 2015094318W WO 2017063244 A1 WO2017063244 A1 WO 2017063244A1
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Prior art keywords
rotor
motor
magnetic induction
circuit
magnetic field
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PCT/CN2015/094318
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English (en)
French (fr)
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白坤
李国民
陆锦锦
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东莞思谷数字技术有限公司
华中科技大学
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Publication of WO2017063244A1 publication Critical patent/WO2017063244A1/zh

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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/06Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/14Electronic commutators
    • H02P6/16Circuit arrangements for detecting position

Definitions

  • the invention belongs to the technical field of motor control, and more particularly to a permanent magnet motor.
  • the existing measurement method relies on decoupling multiple degrees of freedom motion by an external mechanism and measuring them separately with a single-axis encoder.
  • the mechanical decoupling mechanism itself limits the movement of the motor and increases the weight and friction of the entire system, thus seriously affecting the dynamic performance and stability of the motor and the motion system, and the position caused by mechanical wear after a period of use. Declining accuracy is a serious problem.
  • Contact sensors (such as tilt sensor, gyroscope or magnetic field sensor) will be affected by the inertia of the system because they are fixed in the moving part of the motor.
  • the power supply and signal transmission cause the mover to have a wire or bridge circuit, which affects the motor dynamics. Performance, and feedback accuracy is not high.
  • non-contact measurement methods including optical, visual, magnetic field-based and indirect sensorless detection techniques are ideal measurement methods that do not affect the dynamic characteristics of the motor and the overall system.
  • optical and visual sensor technologies rely on higher light requirements in the environment, while sensorless detection technology provides a more accurate rotor position at medium and high speeds, but as the speed decreases, the detection results of this method Poor reliability.
  • the present invention provides a permanent magnet motor in which a magnetic field sensor is embedded in a stator coil of a permanent magnet motor, thereby realizing measurement and control of the rotor position of the motor.
  • a permanent magnet motor including a stator coil and a rotor, further includes an arithmetic module, the arithmetic module including a magnetic field sensor, a first operational circuit, and a second operational circuit connected in sequence;
  • the magnetic field sensor is disposed in the stator coil for detecting the total magnetic induction intensity B 0 and inputting the total magnetic induction intensity B 0 to the first operational circuit;
  • the first operational circuit is configured to pass the total magnetic induction intensity B 0 obtaining the rotor magnetic induction B PM, the magnetic induction B PM and the input of said rotor to said magnetic field sensor generates a second operation circuit; for the second arithmetic circuit via B PM, obtained by The position of the rotor.
  • the permanent magnet motor according to claim 1, wherein the stator coils are M, the magnetic field sensors are N, M>N ⁇ 2, and both M and N are positive integers;
  • the N magnetic field sensors are respectively disposed in the N stator coils, and the N stator coils are respectively disposed at different positions in a motion period of the rotor, and the rotor pair obtained by the first operation circuit is
  • the magnetic induction intensities B PM generated by the N magnetic field sensors are B PM-1 , B PM-2 to B PM-N , respectively .
  • the permanent magnet motor further includes a third operational circuit; the third operational circuit is coupled to the second operational circuit for obtaining a state signal of the rotor by a position of the rotor.
  • the permanent magnet motor further includes a controller and a coil driving module; the controller is coupled to the third computing circuit for inputting a status signal of the rotor to the controller; The controller is configured to give a driving signal according to the state signal of the rotor, and input the driving signal to the coil driving module; the coil driving module is configured to convert the driving signal into a target current, and the A target current is input to the stator coil to achieve control of the motor.
  • the controller is configured to adjust a current driving force signal F w of the motor according to a state signal of the rotor, obtain a target driving force signal of the motor, and generate the target driving force signal Input to the coil driving module; the coil driving module is configured to convert the target driving force signal into a target current, and input the target current into the stator coil, thereby implementing control of the motor.
  • the permanent magnet motor further includes a fourth operational circuit for obtaining a current driving force F w of the motor through a magnetic induction B PM of the rotor.
  • stator coil for the above permanent magnet motor, wherein the stator coil is internally provided with an arithmetic module, and the arithmetic module includes a magnetic field sensor for detecting a total magnetic induction intensity B 0 .
  • the operation module further includes a first operation circuit; the magnetic field sensor is connected to the first operation circuit, and the total magnetic induction intensity B 0 is input to the first operation circuit; the first operation circuit For obtaining the magnetic induction B PM of the rotor in the electric machine by the total magnetic induction B 0 .
  • the operation module further includes an A/D converter and the filter, and the A/D converter and the filter are sequentially connected between the magnetic field sensor and the first operation circuit, the A/D A converter is used to convert the analog signal of the magnetic induction into a digital signal, the filter being used to filter out the noise signal.
  • the module further comprises a second arithmetic operation circuit, said second arithmetic circuit connected to the first arithmetic circuit, and the magnetic induction B PM by the rotor, the position of the motor rotor, the The position of the rotor is the relative position vector R of the rotor and the magnetic field sensor, or the absolute position vector P of the rotor.
  • an arithmetic module for the above permanent magnet motor comprising a magnetic field sensor connected in sequence and a first arithmetic circuit; the magnetic field sensor is arranged in a stator coil of the motor to detect a total magnetic induction intensity B 0 , and inputting the total magnetic induction intensity B 0 to the first operation circuit; the first operation circuit is configured to obtain a magnetic induction intensity B PM of the rotor in the motor by the total magnetic induction intensity B 0 .
  • the operation module further includes a second operation circuit, and the second operation circuit is connected to the first operation circuit for obtaining the position of the rotor by the magnetic induction intensity B PM of the rotor.
  • the magnetic field sensor detects the total magnetic field B 0 of the position where the stator coil is located, B 0 minus the magnetic induction intensity B EM generated by the stator coil, and obtains the magnetic induction intensity B PM generated by the rotor;
  • J is the stator coil current density vector (ie, the current current i of the stator coil divided by the cross-sectional area S of the coil), ⁇ 0 is the permeability of the vacuum, D is the relative position of the magnetic field sensor and the stator coil, and v is the stator The volume of the coil;
  • M is the rotor polarization
  • n is the rotor surface unit normal vector
  • v is the rotor volume
  • s is the rotor surface area
  • R can be calculated by B PM , and then the absolute position vector P of the rotor in the motor can be calculated according to R; or the fitting function of P and B PM can be established directly according to the conversion relationship between R and P, directly by B PM Calculate P.
  • step (3) further comprising the step (4): obtaining a driving signal of the motor according to the state signal of the rotor, converting the driving signal into a target current, and then inputting the target current
  • step (4) obtaining a driving signal of the motor according to the state signal of the rotor, converting the driving signal into a target current, and then inputting the target current
  • the stator coils thereby achieve control of the motor.
  • the step (3) further comprises obtaining, by the B PM and the current current, a current driving force signal F w of the motor.
  • the step (4) is: adjusting a current driving force signal F w of the motor according to a state signal of the rotor to obtain a target driving force signal of the motor, and driving the target The force signal is converted into a target current signal and input to the stator coil to achieve control of the motor.
  • a magnetic field sensor is embedded in the stator coil instead of the prior art method of embedding a sensor in the rotor to measure the rotor position, thereby reducing the mass of the rotor of the motor, thereby reducing the inertial force of the rotor and the required driving force. , improve the dynamic performance of the motor;
  • the current driving force of the motor can be directly calculated by the magnetic induction intensity generated by the rotor of the motor, so that the driving signal can be adjusted to achieve efficient control of the motor.
  • FIG. 1 is a schematic view showing the relative position and force of a single pair of permanent magnets and coils (PM-EM) units in a permanent magnet motor according to the present invention
  • FIG. 2 is a schematic view showing a partial structure of a permanent magnet motor according to the present invention.
  • FIG. 3 is a schematic view showing the internal connection of a permanent magnet motor according to the present invention.
  • FIG. 4 is a schematic structural view of a stator coil of the present invention.
  • FIG. 5 is a schematic structural diagram of a model of a two-degree-of-freedom planar motor system of Embodiment 1;
  • FIG. 6 is a schematic view showing the distribution of the electromagnetic force distribution of the first embodiment and the electromagnetic force distribution when the current is 1 A;
  • 1 - a stator coil provided with an arithmetic module, a 1a-stator coil, a 1b-operation module, a 2-rotor permanent magnet, 3-motor stator.
  • the invention discloses a method for measuring the position of a rotor in a permanent magnet motor, comprising the following steps:
  • Step 1 According to the formula Establish a fitting relationship between the magnetic induction B PM generated by the rotor and the relative position vector R of the magnetic field sensor and the rotor; wherein ⁇ 0 is the permeability of the vacuum, taking 4 ⁇ 10 -7 H/m, and M is the rotor polarization , n is the unit surface normal vector of the rotor surface, v is the rotor volume, and s is the rotor surface area;
  • R can be decomposed into components x, y, z, and the objective function is created by function (2) (3)
  • Bx, By, and Bz are the components of B PM in the x, y, and z directions, respectively, and then the value of (x, y, z) of the minimum value of g is the relative position vector R of the rotor and the magnetic field sensor of the motor. Together with the absolute position of the magnetic field sensor, the absolute position vector P of the motor rotor can be obtained; or P can be directly substituted into the function (2) to establish a fitting function between P and B PM .
  • the electromagnetic driving force expression between a single pair of permanent magnets (PM)-coils (EM) in a motor system is as follows:
  • the electromagnetic driving force F is composed of a normal component and a tangential component, wherein only the tangential component F t along the direction of the stator motion trajectory is an effective force, as shown in FIG.
  • ⁇ , ⁇ , ⁇ can be set as a variable related to R, and f( ⁇ , ⁇ , ⁇ ) is set, so that
  • the variables associated with R may be two or three.
  • the motor drive force can be expressed as the sum of multiple pairs of effective forces, namely:
  • N P is the number of permanent magnets
  • N E is the number of coils
  • R j is a transformation of the relative position vector R between the pairs of stator coils and the rotor permanent magnet to the world coordinate system ( That is, the transformation matrix of the absolute position P) of the rotor of the motor.
  • a closed function [K] associated with B PM can be found to fit
  • the fitting method of the closing function differs depending on the degree of freedom of the motor.
  • Single-degree-of-freedom motors can be fitted using one-dimensional functions, such as polynomial fitting, Gaussian fitting, and Fourier fitting; multi-degree of freedom can be used to establish functional relationships using interpolation or neural networks.
  • Step 2 When the motor is running, measure the position of the rotor of the motor according to the function relationship established above.
  • the specific method is as follows:
  • the magnetic field sensor detects the total magnetic induction intensity B 0 , and the first arithmetic circuit subtracts the magnetic induction intensity B EM generated by the stator coil by B 0 to obtain the magnetic induction intensity B PM generated by the rotor;
  • J is the stator coil current density vector (ie, current i t1 divided by the cross-sectional area of the coil S c )
  • ⁇ 0 is the permeability of the vacuum
  • D is the relative position of the magnetic field sensor and the stator coil
  • v is the stator coil volume.
  • B EM is the sum of the magnetic inductions generated by all the stator coils. However, in the actual measurement process, only a few adjacent stators that have the greatest influence on the magnetic field sensor detection magnetic field are selected according to the system accuracy requirements. The coil is calculated;
  • the second operational circuit calculates the absolute position P of the rotor of the motor through the function (3);
  • the current driving force F w of the motor can be calculated by the absolute position vector R of the motor mover and the current of the coil; or the current driving force of the motor can be obtained directly from the B PM and the coil current by a fitting function such as neural network fitting. w .
  • the characteristics of these two calculation methods are: if the current driving force F w of the motor is calculated by B PM , a fitting function such as a neural network is needed to simulate; but in actual operation, F w is calculated directly by B PM , and the operation is performed. The speed will be faster.
  • the simulation process of the above fitting function is not required by the position P, but it needs to be calculated after the motor mover position P is obtained, and further analysis processing is performed, and the operation speed is delayed.
  • the driving signal such as the current driving force F w of the motor is adjusted to realize the control of the motor, and the working signal is different according to the motor control method.
  • the function (7) gives the forward model of the driving force of the motor. Under the given driving force, the optimal solution of the motor coil current is created, also called the inverse model of the driving force, as shown in function (8):
  • the adjustment of the current driving force signal F w of the motor can be utilized to directly adjust the operating current of the stator coil.
  • the present invention also provides an electric motor, which utilizes the above method to realize measurement of a rotor position and control of a motor, the stator coil and the rotor, and an arithmetic module, wherein the arithmetic module includes a magnetic field sensor sequentially connected, a first operational circuit, and a second operation circuit; the magnetic field sensor is disposed in the stator coil for detecting the total magnetic induction intensity B 0 and inputting the total magnetic induction intensity B 0 to the first operation circuit; the first operation circuit is used to pass the said total magnetic induction B 0, B PM magnetic flux density is obtained of the rotor, and the magnetic induction B PM rotor inputted to the second arithmetic circuit; for the second arithmetic circuit via B PM, obtained by The position P of the rotor.
  • the arithmetic module includes a magnetic field sensor sequentially connected, a first operational circuit, and a second operation circuit; the magnetic field sensor is disposed in the stator coil for detecting the total magnetic induction intensity B
  • the stator coils are usually tens to hundreds, and the magnetic field sensors are at least two, which need to be placed at different positions in a motor cycle of the motor rotor to jointly determine the motor position P, as shown in FIG. Shown.
  • the number of stator coils is M and the number of magnetic field sensors is N, M>N ⁇ 2, and M and N are both positive integers; the N magnetic field sensors are respectively disposed in different stator coils,
  • the magnetic induction B PM of the rotor obtained by the first arithmetic circuit is B PM-1 , B PM-2 to B PM-N , respectively .
  • the second arithmetic circuit obtains the rotor position P through B PM-1 , B PM-2 to B PM-N , and can calculate the relative position vector R of the N magnetic field sensors and the motor rotor separately, and then calculate the absolute of the rotor.
  • the position vector P or directly establish a fitting function of B PM-1 , B PM-2 to B PM-N and P, and then obtain P by a fitting function.
  • the permanent magnet motor may further include a third operation circuit, a controller, and a coil drive module; the second operation circuit and the third operation circuit are sequentially connected to the controller, and the third operation circuit is configured to pass the position of the rotor.
  • the permanent magnet motor may further include a fourth operational circuit for obtaining a current driving force signal F w of the motor through a current current of the B PM and the stator coil.
  • the controller may be configured to adjust the current driving force signal F w according to the state signal of the rotor to obtain a target driving force signal of the motor, and input the target driving force signal to the a coil driving module; the coil driving module is configured to convert the target driving force signal into a target current, and input the target current into the stator coil, thereby implementing control of the motor.
  • the internal connection diagram of the above motor is shown in FIG. 3.
  • the magnetic field sensor is disposed in different stator coils, and the first operation circuit, the second operation circuit, the third operation circuit, and the fourth operation circuit can be disposed in the stator coil. It can also be placed outside the stator coil to measure or further control the position of the rotor in the motor, as shown in Figure 4.
  • the two-degree-of-freedom (x,y) planar motor system model shown in Figure 5 consists of six permanent magnets as stators and one circular coil winding as a mover.
  • the magnets are separated by 5mm, and the spatial position of one of the stator coils is O.
  • the plane of motion of the rotor of the motor in space is the plane coordinate system of the xoy plane.
  • x, y is the spatial position of the rotor of the motor in the plane coordinate system.
  • the third arithmetic circuit calculates the rotor speed, acceleration or inertial force signal of the motor through the rotor position (x, y) of the motor, and inputs the signal to the controller; the controller compares the signal with the working signal of the stator coil and the stator coil The operating current is adjusted to achieve control of the motor.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

一种永磁电机,包括定子线圈(1a)和转子(2),还包括运算模块(1b),运算模块包括依次相连的磁场传感器、第一运算电路以及第二运算电路;磁场传感器设置于定子线圈中,用于检测磁感应强度B0,并将B0输入至第一运算电路;第一运算电路用于通过B0,获得转子对磁场传感器产生的磁感应强度BPM,并将BPM输入至第二运算电路;第二运算电路用于通过BPM,获得转子的位置,转子的状态信号为转子的速度v,加速度a或者惯性力Fi。还公开了用于该永磁电机的定子线圈和运算模块,该用永磁电机可以高效、准确地测量出了电机中转子的位置,进一步实现对电机的精确控制。

Description

一种永磁电机 技术领域
本发明属于电机控制技术领域,更具体地,涉及一种永磁电机。
背景技术
永磁电机的闭环控制过程中,必须实时测量电机转子的位置及转速等状态信号。对于多自由度电机系统来说,现有的测量方法是依靠由外接机构解耦多个自由度运动并用单轴编码器分别测量。机械式的解耦机构本身会限制电机的运动,而且会增加整个系统的自重和摩擦,因而严重影响了电机及运动系统的动态性能和稳定性,同时在使用一段时间后,机械磨损造成的位置精度下降是个严重问题。接触式的传感器(如倾角传感器、陀螺仪或磁场传感器)因为要固定在电机运动部分,首先会影响系统惯性特性,其次而且供电和信号传输使得动子带有导线或桥接电路,影响了电机动态性能,而且反馈精度也不高。
相比传统接触式的测量方式,非接触式的测量方法包括光学、视觉,基于磁场的方法以及间接无传感器检测技术因为不会影响电机和整体系统的动态特性是比较理想的测量方式。然而依赖于光学和视觉的传感器技术对环境中光线的要求比较高,而无传感器检测技术在中、高速时能提供较准确的转子位置,但随着速度的降低,这种方法的检测结果就可靠性较差。
发明内容
针对现有技术的以上缺陷或改进需求,本发明提供了一种永磁电机,在永磁电机的定子线圈中嵌入磁场传感器,从而实现对电机转子位置的测量及控制。
为实现上述目的,按照本发明,提供了一种永磁电机,包括定子线圈 和转子,还包括运算模块,所述运算模块包括依次相连的磁场传感器、第一运算电路以及第二运算电路;所述磁场传感器设置于定子线圈中,用于检测总磁感应强度B0,并将总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述转子的磁感应强度BPM,并将所述转子对所述磁场传感器产生的磁感应强度BPM输入至所述第二运算电路;所述第二运算电路用于通过BPM,获得所述转子的位置。
优选地,如权利要求1所述的永磁电机,其特征在于,所述定子线圈为M个,所述磁场传感器为N个,M>N≥2,且M和N都为正整数;所述N个磁场传感器分别设置于N个所述定子线圈中,N个所述定子线圈分别设置于所述转子的运动周期中的不同位置,所述第一运算电路获得的所述转子对所述N个磁场传感器产生的磁感应强度BPM分别为BPM-1、BPM-2至BPM-N
优选地,所述永磁电机还包括第三运算电路;所述第三运算电路与第二运算电路相连,用于通过所述转子的位置,获得所述转子的状态信号。
作为进一步优选地,所述永磁电机还包括控制器以及线圈驱动模块;所述控制器与所述第三运算电路相连,用于将所述转子的状态信号输入至所述控制器;所述控制器用于根据所述转子的状态信号给出驱动信号,并将所述驱动信号输入至所述线圈驱动模块;所述线圈驱动模块用于将所述驱动信号转换为目标电流,并将所述目标电流输入所述定子线圈,从而实现对电机的控制。
作为进一步优选地,所述控制器用于根据所述转子的状态信号,对所述电机的当前驱动力信号Fw进行调整,得到所述电机的目标驱动力信号,并将所述目标驱动力信号输入至所述线圈驱动模块;所述线圈驱动模块用于将所述目标驱动力信号转换为目标电流,并将所述目标电流输入所述定子线圈,从而实现对电机的控制。
优选地,所述永磁电机还包括第四运算电路,所述第四运算电路用于 通过所述转子的磁感应强度BPM,获得所述电机的当前驱动力Fw
按照本发明,还提供了一种用于上述永磁电机的定子线圈,所述定子线圈内部设置有运算模块,所述运算模块包括磁场传感器,所述磁场传感器用于检测总磁感应强度B0
优选地,所述运算模块还包括第一运算电路;所述磁场传感器与所述第一运算电路相连,将所述总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述电机中转子的磁感应强度BPM
作为进一步优选地,所述运算模块还包括A/D转换器和滤波器,所述A/D转换器和所述滤波器依次连接于磁场传感器与第一运算电路之间,所述A/D转换器用于将所述磁感应强度的模拟信号转换为数字信号,所述滤波器用于滤除噪声信号。
作为进一步优选地,所述运算模块还包括第二运算电路,所述第二运算电路与第一运算电路相连,并通过所述转子的磁感应强度BPM,获得所述电机中转子的位置,所述转子的位置为转子与磁场传感器的相对位置矢量R,或者转子的绝对位置矢量P。
按照本发明,还提供了一种用于上述永磁电机的运算模块,包括依次相连的磁场传感器以及第一运算电路;所述磁场传感器用于设置在电机的定子线圈中,检测总磁感应强度B0,并将所述总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述电机中转子的磁感应强度BPM
优选地,所述运算模块还包括第二运算电路,所述第二运算电路与第一运算电路相连,用于通过所述转子的磁感应强度BPM,获得所述转子的位置。
按照本发明,还提供了一种上述永磁电机中转子位置的测量方法,包括以下步骤:
(1)磁场传感器检测得到定子线圈所在位置的总磁场B0,B0减去定子线圈产生的磁感应强度BEM,得到转子产生的磁感应强度BPM
BEM的计算方法为,
Figure PCTCN2015094318-appb-000001
其中,J为定子线圈电流密度矢量(即定子线圈的当前电流i除以线圈的横截面积S),μ0为真空的磁导率,D为磁场传感器与定子线圈的相对位置,v为定子线圈的体积;
(2)磁场传感器与转子的相对位置矢量R与BPM具有以下的拟合关系:
Figure PCTCN2015094318-appb-000002
其中,M为转子极化强度,n为转子表面单位法向量,v为转子体积,s为转子表面积;
根据式2,可以通过BPM计算得到R,然后根据R计算得到电机中转子的绝对位置矢量P;或者直接根据R与P的换算关系,建立P与BPM的拟合函数,直接由BPM计算得到P。
(3)根据P,计算得到转子的状态信号,所述转子的状态信号为转子的速度v,加速度a或者惯性力Fi;其中,v=△P/△t,a=△v/△t,Fi=ma,t为时间,m为电机转子的质量。
优选地,在步骤(3)之后,还包括步骤(4):根据所述转子的状态信号得到所述电机的驱动信号,并将所述驱动信号转换为目标电流,然后将所述目标电流输入所述定子线圈,从而实现对电机的控制。
优选地,所述步骤(3)还包括,通过BPM和当前电流,获得所述电机的当前驱动力信号Fw
作为进一步优选地,所述步骤(4)为:根据所述转子的状态信号,对所述电机的当前驱动力信号Fw进行调整,得到所述电机的目标驱动力信号,将所述目标驱动力信号转换为目标电流信号,并输入所述定子线圈,从而实现对电机的控制。
总体而言,通过本发明所构思的以上技术方案与现有技术相比,能够取得下列有益效果:
1、在定子线圈中嵌入安装磁场传感器,取代现有技术中在转子中嵌入传感器来测量转子位置的方法,减小了电机转子的质量,从而减小了转子的惯性力和所需的驱动力,提高了电机的动态性能;
2、不依赖光学传感器,对环境光线无要求,即使在带有粉尘的环境中也可以实现;
3、利用设置于不同定子线圈中的磁场传感器,使得转子位置的检测更加精确;
4、可通过电机转子产生的磁感应强度,直接计算得到电机当前的驱动力,从而对驱动信号进行调整,实现了对电机的高效控制。
附图说明
图1为本发明永磁电机内部单对永磁铁与线圈(PM-EM)单元相对位置及受力示意图;
图2为本发明永磁电机局部结构示意图;
图3为本发明永磁电机内部连接示意图;
图4为本发明定子线圈结构示意图;
图5为实施例1的两自由度平面电机系统模型结构示意图;
图6为实施例1的磁感应强度分布与电流为1A时的电磁力分布示意图;
在所有附图中,相同的附图标记用来表示相同的元件或结构,其中:1-设置有运算模块的定子线圈,1a-定子线圈,1b-运算模块,2-转子永磁铁, 3-电机定子。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白,以下结合附图及实施例,对本发明进行进一步详细说明。应当理解,此处所描述的具体实施例仅用以解释本发明,并不用于限定本发明。此外,下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
本发明公开了一种永磁电机中转子位置的测量方法,包括以下步骤:
步骤一:根据公式
Figure PCTCN2015094318-appb-000003
Figure PCTCN2015094318-appb-000004
建立转子产生的磁感应强度BPM与磁场传感器与转子的相对位置矢量R的拟合关系;其中,μ0为真空的磁导率,取4π×10-7H/m,M为转子极化强度,n为转子表面单位法向量,v为转子体积,s为转子表面积;
在笛卡尔坐标系中,R可以分解为分量x、y、z,通过函数(2),创建目标函数(3)
g=(Bx(R)-Bx')2+(By(R)-By')2+(Bz(R)-Bz')2或g=|Bx(R)-Bx'|+|By(R)-By'|+|Bz(R)-Bz'|……(3)
其中,Bx、By和Bz分别为BPM在x、y、z方向上的分量,则当g取最小值的(x,y,z)值,即为电机转子与磁场传感器的相对位置矢量R,再加上磁场传感器的绝对位置,即可以得到电机转子的绝对位置矢量P;或者直接把P代入函数(2),建立P与BPM的拟合函数。
同时,还可以建立电机当前的驱动力Fw与BPM的拟合函数,具体方法如下:
由于电机系统中单对永磁铁(PM)-线圈(EM)之间的电磁驱动力表达式如下:
F=-i∫vBPM×dl……(4)
其中,i为线圈所通电流大小,dl为线圈电流方向,v为线圈的体积。在自然坐标系中,电磁驱动力F由法向分量和切向分量组成,其中,只有沿定子运动轨迹方向的切向分量Ft为有效作用力,如图1所示。
由于BPM只和磁场传感器与定子线圈的相对位置矢量R有关,则可以设置η,ζ,σ为与R相关的变量,设置f(η,ζ,σ),使得
Ft=-i[fη(η,ζ,σ)eη+fζ(η,ζ,σ)eζ]……(5)
其中,根据电机自由度不同,与R相关的变量可能为2个或3个。
对于整个电机系统,包含多个转子永磁铁与线圈(PMs-EMs),电机驱动力可表示为多对有效作用力之和,即:
Figure PCTCN2015094318-appb-000005
其中,ij为j号线圈所通电流大小,NP为永磁铁数目,NE为线圈数目,Rj为将多对定子线圈和转子永磁铁之间相对位置矢量R变换至世界坐标系(即电机转子的绝对位置P)的变换矩阵。
可以找到一个与BPM相关的闭合函数[K]来拟合
Figure PCTCN2015094318-appb-000006
使得
Figure PCTCN2015094318-appb-000007
时,则FW=[K][u]                 ……(7)
根据电机的自由度而不同,闭合函数的拟合方法也不同。单自由度电机可使用一维函数来拟合,如多项式拟合、高斯拟合、傅里叶拟合等方式;多自由度可使用插值或神经网络建立函数关系。
步骤二:电机运行时,根据以上建立的函数关系对电机转子的位置进行测量,其具体方法如下:
(1)磁场传感器检测得到总磁感应强度B0,第一运算电路用B0减去 定子线圈产生的磁感应强度BEM,得到转子产生的磁感应强度BPM
BEM的计算方法为,
Figure PCTCN2015094318-appb-000008
其中,J为定子线圈电流密度矢量(即电流it1除以线圈的横截面积Sc),μ0为真空的磁导率,D为磁场传感器与定子线圈的相对位置,v为定子线圈的体积。如果电机有多个定子线圈,BEM为所有定子线圈产生的磁感应强度之和,但在实际测量过程中,只需要根据系统精度要求,选择对磁场传感器检测磁场影响效果最大的几个相邻定子线圈进行计算;
(2)第二运算电路通过函数(3),计算得到电机转子的绝对位置P;
在一个电机的运动周期中,电机转子在不同的位置有可能产生相同的BPM值,即根据拟合函数3,可能有不同的R解。因此需要将2个至数十个磁场传感器设置于电机转子运动周期中的不同位置,以根据不同第一运算电路求得的BPM-1、BPM-2…以及BPM-N,从而确定多个磁场传感器与电机转子的相对位置矢量R1、R2至RN,然后得到P;或者通过P与BPM-1、BPM-2至BPM-N的拟合函数,直接得到P。
通过电机动子的绝对位置矢量R以及线圈的电流,可以计算出电机当前的驱动力Fw;或者通过拟合函数如神经网络拟合,直接根据BPM和线圈电流获得电机当前的驱动力Fw。这两种计算方法的特点是:如果通过BPM计算出电机当前的驱动力Fw,需要建立拟合函数如神经网络进行模拟;但在实际运行时,直接通过BPM计算得到Fw,运算速度会更快。而通过位置P获得,不需要上述拟合函数的模拟过程,但需要经过计算电机动子位置P后,再经过进一步的分析处理得到,运算速度会有一定延迟。
(3)根据v=△P/△t,a=△v/△t,Fi=ma,其中,t为时间,m为电机转子的质量,第三运算电路通过电机转子的绝对位置矢量P,获得电机转子的状态信号,如转子的速度v、加速度a、或者惯性力Fi
(4)根据步骤(3)中的状态信号以及系统给定的工作信号,对驱动信号如电机当前的驱动力Fw进行调整,从而实现对电机的控制,根据电机控制方法的不同,工作信号可能为电压信号,速度信号或者位置信号。
函数(7)给出了电机的驱动力正向模型,在给定驱动力的情况下,创建电机线圈电流的优化解,也称为驱动力的逆模型,如函数(8)所示:
u=[K]T([K][K]T)-1Fw……8
通过该模型,可以利用对电机当前的驱动力信号Fw的调整,从而直接对定子线圈的工作电流进行调整。
本发明还提供了一种电机,利用上述方法实现转子位置的测量以及电机的控制,该包括定子线圈和转子,还包括运算模块,所述运算模块包括依次相连的磁场传感器、第一运算电路以及第二运算电路;所述磁场传感器设置于定子线圈中,用于检测总磁感应强度B0,并将总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述转子的磁感应强度BPM,并将所述转子的磁感应强度BPM输入至所述第二运算电路;所述第二运算电路用于通过BPM,获得所述转子的位置P。
在二维或多维电机系统中,定子线圈通常为数十至数百个,而磁场传感器至少为两个,需要设置于电机转子一个运动周期中的不同位置,共同确定电机位置P,如图2所示。当定子线圈的数量为M个,磁场传感器的数量为N个时,M>N≥2,且M和N都为正整数;所述N个磁场传感器分别设置于不同的所述定子线圈中,所述第一运算电路获得的所述转子的磁感应强度BPM分别为BPM-1、BPM-2至BPM-N。第二运算电路则通过BPM-1、BPM-2至BPM-N,获得转子位置P,可以先分别计算出N个磁场传感器与电机转子的相对位置矢量R,再计算出转子的绝对位置矢量P,或者先事先直接建立BPM-1、BPM-2至BPM-N与P的拟合函数,然后通过拟合函数求出P。
所述永磁电机还可以包括第三运算电路、控制器以及线圈驱动模块;所述第二运算电路、第三运算电路与控制器依次相连,第三运算电路用于通过所述转子的位置,获得所述转子的状态信号;所述控制器用于接收所述转子的状态信号,并根据所述转子的状态信号以及系统给定的工作信号对驱动信号(如转子的速度信号、转矩信号、位置信号等)进行调整,再将所述驱动信号输入所述线圈驱动模块,所述线圈驱动模块用于将驱动信号转换为输入定子线圈的目标电流,从而实现对电机的控制。
所述永磁电机还可以包括第四运算电路,所述第四运算电路用于通过BPM和定子线圈的当前电流,获得所述电机的当前驱动力信号Fw。此时,所述控制器可以用于根据所述转子的状态信号,对当前驱动力信号Fw进行调整,得到所述电机的目标驱动力信号,并将所述目标驱动力信号输入至所述线圈驱动模块;所述线圈驱动模块用于将所述目标驱动力信号转换为目标电流,并将所述目标电流输入所述定子线圈,从而实现对电机的控制。
上述电机的内部连接示意图如图3所示,磁场传感器设置于不同的定子线圈中,第一运算电路、第二运算电路、第三运算电路以及第四运算电路既可以设置于定子线圈之中,也可以设置于定子线圈之外,从而对电机中转子的位置进行测量或者进一步的控制,如图4所示。
实施例1
如图5所示的两自由度(x,y)平面电机系统模型,由六个永磁铁作为定子和一个圆形线圈绕组作为动子组成,永磁铁(PM)与定子线圈(EM)的尺寸如下表一所示,其中ao表示直径,l表示高度ai表示定子线圈的内径,d表示定子线圈的内径,M0表示永磁铁的磁化强度,μ0表示真空的磁导率,各个永磁铁相距5mm,以其中一个定子线圈的空间位置为O点,电机转子在空间中的运动平面为xoy平面建立平面坐标系,则x,y为平面坐标系内电机转子的空间位置。
表1
Figure PCTCN2015094318-appb-000009
根据表1中的电机参数,分别计算出单对PM-EM间的磁感应强度分布与电磁力分布,对其进行拟合,直接得到永磁铁周围的三轴磁感应强度拟合函数Bx(x,y)、By(x,y)和Bz(x,y),以及电流为1A时的驱动力分布函数Fx(x,y)、Fy(x,y),分别如图6a-图6e所示。
电机运行时,检测转子位置的具体方法如下:
(1)霍尔传感器检测到的磁感应强度值B0,并把该信号输入第一运算电路;通过B0=BPM+BEM以及
Figure PCTCN2015094318-appb-000010
得到电机转子产生的磁感应强度BPM,并把该信号输入第二运算电路;
(2)根据步骤一得到的拟合函数创建新函数g=(Bx(x,y)-Bx')2+(By(x,y)-By')2+(Bz(x,y)-Bz')2,第二运算电路利用无约束优化算法,计算新函数f的最小值min.f=0,此时的位置(x,y)即为电机转子的当前空间位置,第二运算电路把(x,y)输入第三运算电路;
(3)第三运算电路通过电机转子位置(x,y),计算得到电机转子速度、加速度或者惯性力信号,输入控制器;控制器将上述信号与定子线圈的工作信号相比较并对定子线圈的工作电流进行调整,从而实现对该电机的控制。
本领域的技术人员容易理解,以上所述仅为本发明的较佳实施例而已,并不用以限制本发明,凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等,均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种永磁电机,包括定子线圈和转子,其特征在于,还包括运算模块,所述运算模块包括依次相连的磁场传感器、第一运算电路以及第二运算电路;所述磁场传感器设置于定子线圈中,用于检测总磁感应强度B0,并将总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述转子的磁感应强度BPM,并将所述转子的磁感应强度BPM输入至所述第二运算电路;所述第二运算电路用于通过BPM,获得所述转子的位置。
  2. 如权利要求1所述的永磁电机,其特征在于,所述定子线圈为M个,所述磁场传感器为N个,M>N≥2,且M和N都为正整数;所述N个磁场传感器分别设置于N个所述定子线圈中,所述第一运算电路获得的所述转子的磁感应强度BPM分别为BPM-1、BPM-2至BPM-N
  3. 如权利要求1所述的永磁电机,其特征在于,还包括第三运算电路;所述第三运算电路与第二运算电路相连,用于通过所述转子的位置,获得所述转子的状态信号。
  4. 如权利要求3所述的永磁电机,其特征在于,还包括控制器以及线圈驱动模块;所述控制器与所述第三运算电路相连,用于将所述转子的状态信号输入至所述控制器;所述控制器用于根据所述转子的状态信号给出驱动信号,并将所述驱动信号输入至所述线圈驱动模块;所述线圈驱动模块用于将所述驱动信号转换为目标电流,并将所述目标电流输入所述定子线圈,从而实现对电机的控制。
  5. 如权利要求1所述的永磁电机,其特征在于,还包括第四运算电路,所述第四运算电路用于通过所述转子的磁感应强度BPM,获得所述电机的当前驱动力Fw。
  6. 一种用于如权利要求1-5中任意一项所述永磁电机的定子线圈,其 特征在于,所述定子线圈内部设置有运算模块,所述运算模块包括磁场传感器,所述磁场传感器用于检测总磁感应强度B0
  7. 如权利要求6所述的定子线圈,其特征在于,所述运算模块还包括第一运算电路;所述磁场传感器与所述第一运算电路相连,将所述总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述电机中转子的磁感应强度BPM
  8. 如权利要求7所述的定子线圈,其特征在于,所述运算模块还包括第二运算电路,所述第二运算电路与第一运算电路相连,并通过所述转子的磁感应强度BPM,获得所述电机中转子的位置。
  9. 一种用于如权利要求1所述永磁电机的运算模块,其特征在于,包括依次相连的磁场传感器以及第一运算电路;所述磁场传感器用于设置在电机的定子线圈中,检测总磁感应强度B0,并将所述总磁感应强度B0输入至所述第一运算电路;所述第一运算电路用于通过所述总磁感应强度B0,获得所述电机中转子的磁感应强度BPM
  10. 如权利要求9所述的运算模块,其特征在于,还包括第二运算电路,所述第二运算电路与第一运算电路相连,用于通过所述转子的磁感应强度BPM,获得所述转子的位置。
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