Method for reducing electromagnetic vibration of permanent magnet motor with fractional slot concentrated winding

Patent metadata

Field	Value
Publication number	US-2024106360-A1
Application number	US-202118038215-A
Country	US
Kind code	A1
Filing date	Mar 2, 2021
Priority date	Feb 24, 2021
Publication date	Mar 28, 2024
Grant date	—

Abstract

The present disclosure provides a method for reducing the electromagnetic vibration of a fractional slot concentrated winding (FSCW) permanent magnet (PM) motor, which provides a guidance for the low vibration design of FSCW PM motor. The implementation of the method includes: Based on Nyquist Shannon sampling theorem, the modulation effect of electromagnetic force in the air gap is obtained, and the electromagnetic force component that contributes the most to the electromagnetic vibration of the FSCW PM motor is determined. The equivalent analytical model of PM flux density is established to obtain the phase relationship between different flux density harmonics. According to Maxwell stress equation, the internal relationship between each order of flux density harmonics and electromagnetic force harmonics is obtained. A new magnet structure of the PM motor is designed, and specific flux density harmonics are injected to reduce the electromagnetic force and electromagnetic vibration of the FSCW PM motor.

First claim

1 . A method for reducing electromagnetic vibration of a fractional slot concentrated winding (FSCW) permanent magnet (PM) motor, comprising:
step 1: based on Nyquist Shannon sampling theorem, a mathematical expression of an electromagnetic force modulation effect of the FSCW PM motor is derived; step 2: a contribution of each order of electromagnetic force to an electromagnetic vibration of a FSCW PM motor is evaluated, and a harmonic component of an electromagnetic force that plays a major role in the electromagnetic vibration of the FSCW PM motor is identified; step 3: an equivalent model of a PM flux density is established, and a phase relationship between harmonics of different magnetic flux density is explored; step 4: according to Maxwell stress equation, a relationship between the flux density harmonics and a main electromagnetic force harmonic is obtained, and a phase relationship between different electromagnetic force harmonic components is obtained; step 5: a segmented magnet structure is designed, and a magnetic flux density harmonic in the FSCW PM motor are increased to reduce an amplitude of the electromagnetic force and the electromagnetic vibration, wherein the step 5 specifically comprises:
there is a phase superposition or cancellation effect between electromagnetic force harmonics, and a magnetic flux density harmonic source of an electromagnetic force component that plays a cancellation role is identified;
in order to achieve an effect of a flux density harmonic injection, each magnet is divided into three sections, and a remanence of the PM material at both ends is higher than a remanence of a middle one;
an electromagnetic force generated by the harmonic of the injected flux density harmonics counteracts an electromagnetic force generated by the fundamental magnetic field, achieving an effect of reducing a synthesized radial electromagnetic force and the electromagnetic vibration; and
step 6: a multiphysics electromagnetic vibration simulation model is established, and an electromagnetic vibration suppression effect of the FSCW PM motor is verified.

2 . The method for reducing the electromagnetic vibration of the FSCW PM motor according to claim 1 , wherein
the FSCW PM motor is a three-phase surface-mounted PM motor with 12 slots and 10 poles, including a stator, an air gap, and a rotor, the stator includes a stator yoke, stator teeth, stator teeth pole shoes, stator slots between the stator teeth, and armature windings inside the stator slot, a material of the stator core is silicon steel sheet and the armature windings adopt a fractional slot concentrated winding topology, the air gap is between the stator and rotor, the rotor is evenly perforated, and a material of the rotor iron core is silicon steel sheet, permanent magnets are attached to a surface of the cylindrical rotor iron core and a cross-section of the surface is rectangular, and each magnet of the FSCW PM motor is blocked into three sections, wherein a residual flux density of the magnets on both sides of each pole is higher than a residual flux density of the middle one.

3 . The method for reducing the electromagnetic vibration of the FSCW according to claim 1 , wherein specific steps of the step 1 specifically comprises:
firstly, an air gap electromagnetic force harmonic is Fourier transformed, and then sampled signals are Fourier decomposed; an output signal of a modulated electromagnetic force is expressed as a multiplication of an electromagnetic force density and the sampled signals, and the modulated electromagnetic force is expressed by using a frequency domain convolution theorem; and according to the Nyquist Shannon sampling theorem, when a spatial order of the electromagnetic force is greater than half of a number of stator teeth, the spatial order of the electromagnetic force will change, and a higher-order electromagnetic force harmonic will be modulated into a lower order electromagnetic force components.

4 . The method for reducing the electromagnetic vibration of the FSCW PM motor according to claim 1 , wherein specific steps of the step 2 specifically comprises:
a stator of the FSCW PM motor is equivalent to a cylinder structure, and a mathematical relationship between the vibration displacement and an electromagnetic force spatial order of the FSCW PM motor is obtained; when a spatial order of the electromagnetic force v≥2, the vibration displacement of an equivalent cylinder is approximately inversely proportional to a fourth power of the spatial order of the electromagnetic force; therefore, the influence of electromagnetic force with high spatial order on vibration is ignored; high order electromagnetic force harmonics are modulated into low order ones force harmonics; and contributions of different electromagnetic force harmonics to electromagnetic vibration of the FSCW PM motor are evaluated and compared.

5 . The method for reducing the electromagnetic vibration of the fractional slot concentrated winding permanent magnet motor according to claim 1 , wherein specific steps of the step 3 specifically comprises:
a PM flux density waveform is approximately equivalent to a square wave signal, and a spatial order and a corresponding initial phase of the flux density harmonics are obtained; since the square wave signal satisfies Dirichlet condition, Fourier coefficient of the square wave signal is obtained; a spatial order of a PM radial flux density harmonic, and a corresponding initial phase angle, as well as the phase relationship between each flux density harmonic are obtained; and since an initial phase angle of the PM radial flux density harmonic is π/2 rad ahead of a tangential flux density harmonic, a spatial order and an initial phase angle of a PM tangential flux density harmonic are obtained.

6 . The method for reducing the electromagnetic vibration of the FSCW PM motor according to claim 1 , wherein specific steps of the step 4 specifically comprises:
a phase relationship between harmonic components of a main electromagnetic force is obtained, and a mapping relationship between harmonic components of a magnetic flux density and harmonic components of the main electromagnetic force is obtained; according to Maxwell stress tensor method, a mathematical relationship between radial and tangential electromagnetic forces and radial and tangential magnetic flux density is expressed; since a magnetic flux density is a function of time and space, electromagnetic force harmonics of each order also have a specific spatial order, time frequency and initial phase angle; electromagnetic force harmonics with a same spatial order and time frequency have different initial phase angles, so there is a superposition or cancellation effect between the electromagnetic force harmonics; each order of magnetic flux density harmonics is expressed as a function of the spatial order, time frequency and initial phase angle; and according to Maxwell tensor method, a mapping relationship between the magnetic flux density harmonics and the main electromagnetic force harmonic, and the phase relationship between electromagnetic force harmonic components are obtained.

7 . (canceled)

8 . The method for reducing the electromagnetic vibration of the FSCW PM motor according to claim 1 , wherein specific steps of the step 6 specifically comprises:
a multiphysics field electromagnetic vibration simulation model is established, and the electromagnetic vibration suppression effect of the FSCW PM motor is verified; two numerical software, Flux and LMS Virtual. Lab Acoustics, are used to simulate the electromagnetic vibration and a noise of the FSCW PM motor; optimized parameters of the FSCW PM motor will be set in the Flux, which is an elect

Assignees

• Univ Jiangsu

Inventors

• Zhao Wenxiang
• Zhu Shengdao
• Liu Guohai
• Ji Jinghua

Classifications

• H02P21/05 Primary

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title

• H02K1/2766

  having a flux concentration effect · CPC title

• H02P21/141

  Flux estimation · CPC title

• H02K2213/03

  Machines characterised by numerical values, ranges, mathematical expressions or similar information · CPC title

• H02P21/0017

  Model reference adaptation, e.g. MRAS or MRAC, useful for control or parameter estimation · CPC title