Suspension Force Research Articles

Research on Fast Design of Key Variables of Bearingless Flux-Switching Motor Based on Variable Structure Magnetic Network

The bearingless flux-switching permanent magnet motor (BFSPMM) adopts the stator permanent magnet structure, which is beneficial to the heat dissipation of the permanent magnet and reduces the risk of demagnetization caused by the temperature rise of the permanent magnet. However, since BFSPMM adopts the double-salient structure, the design method of the traditional rotor permanent magnet type motor with sine wave back electromotive force cannot be directly applied. Thus, the design of the BFSPMM is complicated and time consuming. To this end, this paper proposes a method to quickly design the key parameters of the BFSPMM, such as optimum tooth width ratio, electromagnetic torque, winding coupled permanent magnet flux, suspension force, etc. First, in order to overcome the shortcoming of finite element time consuming, a new variable structure magnetic network model (VSMNM) of the BFSPMM is built considering the eccentricity of rotor. Second, the expressions of the optimal rotor-to-stator tooth width ratio and the coupling permanent magnet flux linkage in power winding are directly deduced based on the proposed VSMNM. Then, the electromagnetic torque is deduced based on the permanent magnet flux linkage, and the suspension force is deduced based on VSMNM. Finally, the fast design method proposed in this paper is verified to be effective by the finite-element analysis and the experimental results.

Modeling and Performance Analysis on the Slice Hybrid Magnetic Bearing With Two Radial Air-Gaps

In order to reduce the axial length and increase the critical speed of the small magnetic suspension drive system, a new slice hybrid magnetic bearing (SHMB) with two radial air-gaps is proposed. The structure and suspension mechanism of the SHMB is introduced, and then the mathematical models of the radial suspension force are deduced using the equivalent magnetic circuit method. The suspension mechanism is proved. The radial and axial suspension forces are then calculated by the finite element method. The experimental prototype SHMB is finally designed and constructed. The stable suspension of the rotor is realized, and the suspension forces are measured. The results of the finite element calculation and experimental measurement verify the correctness of the mathematical models.

Performance comparison of 12/12 pole with 8/10 and 12/14 pole bearingless switched reluctance machine

In this Letter, three types of bearingless switched reluctance machines (BSRMs) with different hybrid stator structures are designed and analysed. First of all, topologies of three BSRMs, the conventional 8/10 pole, 12/14 pole BSRMs and a novel 12/12 pole BSRM with axial split phase inner stator permanent magnet structure, are given. Then, the electromagnetic performances, including the distribution of magnetic fields, suspension force and electromagnetic torque are comprehensively compared by means of 2D and 3D finite-element method (FEM). The results based on theoretical analysis and FEM reveal that the proposed 12/12 pole BSRM would exhibit complete decoupling, shorter magnetic circuit, higher torque (power) density and suspension force than the conventional ones. Further, it is found that four degree-of-freedom suspension of the rotor can be realised by two-phase suspension windings in the proposed 12/12 pole BSRM. Finally, a prototype machine is designed and manufactured to verify the validity of the topology design and electromagnetic performance.

Modeling and Operation of a Bearingless Fixed-Pole Rotor Induction Motor

The rotor currents are induced by both suspension force winding magnetic field and torque winding magnetic field in the traditional bearingless induction motors (BIMs). Due to the currents induced by the suspension force winding, there are errors in the generation of radial suspension forces. To address such problems, a novel BIM with fixed-pole rotor, called bearingless fixed-pole rotor induction (BFPRI) motor is proposed. The structure of BFPRI motor is first analyzed and the mathematical models of radial suspension forces are deduced. Based on the finite element analysis, the induced currents and radial suspension forces are also investigated and compared with the traditional BIM. Finally, the prototype motor is built and experimental research is carried out. In this novel motor, only the torque winding magnetic field induces currents in the rotor, which makes the precision of radial suspension forces higher and thereby reduces the complexity of BIM control system. The effectiveness of the proposed BFPRI motor is validated by both simulation and experiments.

Performance Improvement of Torque and Suspension Force for a Novel Five-Phase BFSPM Machine for Flywheel Energy Storage Systems

To improve the electromagnetic performance of the machine for a flywheel energy storage system, in this paper, a five-phase bearingless flux-switching permanent magnet machine with an E-core stator is presented. The topology and structure are introduced and the operation principle of the generation of torque and suspension force is also explained. Based on the simple variable method and overall trial and error method, the influence of the machine parameters on machine performance is investigated by using a finite element analysis. Then, the parameters are optimized. The results show the improvement of the torque and suspension force with increased amplitude and smaller fluctuation.

Modeling and Performance Analysis on the Five Degrees of Freedom Slice Hybrid Magnetic Bearing

To reduce the volume of the five degrees of freedom (DOF) magnetic suspension system and increase the critical speed, a slice hybrid magnetic bearing (SHMB) is proposed. First, the mathematical models of the radial suspension are deduced using the equivalent magnetic circuit method based on the suspension mechanism analysis. Then, the parameters of the five-DOF SHMB are designed. The magnetic circuits are analyzed, and the relationships between the radial suspension force and the suspension currents are calculated. Furthermore, the relationships between the axial force and the axial offset are also calculated. Finally, The experimental prototype five-DOF SHMB is designed and the suspension forces are tested. The research results have shown that the rotor can be levitated stably in five DOF.

Research on the Design Method of a Bionic Suspension Workpiece Based on the Wing Structure of an Albatross.

An air suspension platform uses air pressure to realize the suspension function during the suspension process, and it has the disadvantage of large air pressure and a small suspension force. In this study, an air suspension platform was built using bionic design to reduce the required air pressure and increase the suspension force. A suspension structure mapping model was established according to the physiological structure characteristics of albatross wings. A bionic model was established by using the theoretical calculation formula and structural size parameters of the structural design. A 3D printer was used to manufacture the physical prototype of the suspended workpiece. Based on this, a suspension test rig was built. Six sets of contrast experiments were designed. The experimental results of the suspension test bench were compared with the theoretical calculation results. The results show that the buoyancy of the suspended workpiece with a V-shaped surface at a 15-degree attack angle was optimal for the same air pressure as the other workpieces. The surface structure of the suspended workpiece was applied to the air static pressure guide rail. By comparing the experimental data, the air pressure of the original air suspension guide rail was reduced by 37%, and the validity of the theory and design method was verified.

Analysis and Evaluation on Unloading Ratio of Zero-g Simulation System Based on Torques of Space Manipulator

SummaryIn this paper, a dynamic model of a seven-joints manipulator operated in a zero-g simulation system is established. The errors of the friction, the suspension force, and the flexible deformation of arms are considered. Furthermore, the unloading ratio, which can evaluate the performance of the simulation system, is presented. It can reflect the level of similarity between the system and the space environment directly and effectively. The results of experimental and theoretical analyses verify the correctness of the model. It helps us to get the joint torques when the actual space manipulator without the torque sensor operates in this system and guarantees the safety of the experiments.

Modelling and performance analysis on a bearingless fixed‐pole rotor induction motor

Both torque winding magnetic field and suspension force winding magnetic field induce currents in the rotor in conventional bearingless induction motors (BIMs). Owing to the induced currents of suspension force winding, the air gap magnetic field is affected, which results in amplitude and phase error of torque and radial suspension forces. To overcome such drawbacks, a novel BIM with a fixed-pole rotor is proposed, which is called bearingless fixed-pole rotor induction (BFPRI) motor. First, the structure of the BFPRI motor is designed and introduced. Second, the mathematical models of radial suspension forces and torque are deduced. Third, the corresponding electromagnetic characteristics, including induced currents, radial suspension forces, and torque, are investigated and compared with the conventional BIM. Finally, the prototype motor equipped with a fixed-pole rotor is constructed and experimental research is carried out. According to the finite element analysis and experimental results, for the proposed BFPRI motor, only the torque winding magnetic field induces currents in the rotor, which makes the precision of torque and radial suspension forces higher and improves the accuracy of the BIM control system.

Vehicle centre of mass, roll-centre and pitch-centre height estimation

The location of a vehicle's centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres has a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles due to the large differences in laden and unladen weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an offroad vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control.

Analytical Calculation of Electromagnetic Performances of Bearingless Flux-Switching Permanent-Magnet Machine Considering Iron Saturation Based on Exact Subdomain Model

In this paper, an accurate analytical subdomain model to calculate electromagnetic performances of bearingless flux-switching permanent magnet (BFSPM) machines is developed. The entire region of the machine is divided into six subdomains, including slots, air gap, magnets, and so on. According to the Neumann boundary conditions between the subdomains and the iron and the continuity conditions at the interface between the adjacent subdomains, the magnetic field distributions of subdomains are obtained by solving the Maxwell equations. In addition, a method to compensate the saturation effect is proposed, and the magnetic saturation of the stator and rotor is considered by the actual B-H characteristics. Based on the proposed analytical method, the air-gap flux density distributions of the machine with different iron material under linear and nonlinear conditions are predicted. Further, the electromagnetic performances including the cogging torque, electromagnetic torque, flux linkage, back-EMF, inductance, and suspension force are calculated. These analytical results are compared with those obtained by the Finite Element Analysis (FEA) to verify the accuracy of the proposed analytical method.

Design and Analysis of a Novel Bearingless Segmented Switched Reluctance Motor

A novel bearingless segmented switched reluctance motor (BSSRM) is proposed in this paper to solve the coupling problem of the traditional bearingless switched reluctance motor (BSRM). Different from traditional BSRMs, the proposed BSSRM adopts the double stator and segmented rotor structure, thereby making the motor operate in short flux paths and the magnetic flux path isolated between torque and suspension system. On the basis of introducing the structure and working principle of the BSSRM, the mathematical model of torque and suspension force is deduced. The 2D finite element simulation model is established by the Ansoft software. The influence of structural parameters on torque and suspension system is analyzed, and its electromagnetic characteristic and decoupling characteristic are analyzed. Compared with the double stator bearingless switched reluctance motor (DSBSRM), the BSSRM not only improves the torque and suspension output but also weakens the coupling between torque and suspension system. Finally, the simulation results verify the effectiveness of the BSSRM.

Electromagnetic Performance Analysis on the Bearingless Permanent Magnet Synchronous Motor With Halbach Magnetized Rotor

In order to approximately obtain sinusoidal air-gap magnetic field and get larger radial levitation force of the bearingless permanent magnet synchronous motor (BPMSM), a novel BPMSM with Halbach magnetized rotor is proposed. Firstly, the suspension and rotation mechanisms of the BPMSM are introduced. The control mechanism of producing the radial levitation force in single direction and arbitrary direction is analyzed in detail. The mathematical models of the radial suspension force are given. Secondly, the comparative research on the BPMSMs with the Halbach magnetized rotor and parallel magnetized rotor is carried out. The air-gap magnetic field, back electromotive force (EMF), radial suspension force, and torque are calculated and compared. Finally, the prototype motor equipped with the Halbach magnetized rotor is constructed. Some experimental results are tested and the stable suspension operation of the proposed motor is realized.

Direct Torque and Suspension Force Control for Bearingless Induction Motors Based on Active Disturbance Rejection Control Scheme

The bearingless induction motor (BIM) system has the characteristics of non-linear, strongly coupled, and highly accurate. To achieve the stable and accurate control of BIM, the methods of direct torque control (DTC) and direct suspension force control (DSFC) based on space vector modulation (SVM) are introduced first. However, the dynamic performance and uncertain anti-jamming robustness of the system need to be further researched. Based on the BIM control system, the active disturbance rejection control (ADRC) technology is selected in this paper. The total disturbance of the system is estimated in real time by using the extended state observer (ESO). According to the estimated value of the ESO, the disturbance can be compensated by the ADRC in time to eliminate the steady-state tracking error to achieve good anti-interference performance. The ADRC-based direct torque and suspension force control system for the BIM is designed and simulated by the MATLAB software. The simulation and experiment results show that the ADRC technology can effectively suppress the impact of load disturbance, reduce the overshoot, and have strong robustness.

Control of Axial Suspension Force and Torque for a Slotless Single-Drive Bearingless Motor

Control of Axial Suspension Force and Torque for a Slotless Single-Drive Bearingless Motor

The Study of Switched Reluctance Motor for 4-DOF Bearingless Motor

High integration, low loss and high-reliability are the main development trends of flywheel battery. Thus this study presents the first prototype of a novel high-integration four degrees of freedom (4-DOF) bearingless motor with the advantages of weak coupling and low power consumption. The proposed bearingless motor can realize energy conversion and produce 4-DOF radial forces compared with the conventional bearingless motor for improving the integration of system. A biased flux for producing radial levitation forces is provided by the permanent magnets, which reduce the power consumption of the system. Moreover, a decoupling between the torque and the suspension systems is realized through a structural design, thereby improving the controllability. Structure and winding configurations are introduced and the operation principle of the 4-DOF bearingless motor is discussed. Magnetic circuits analysis and parameter design method are present and a three-dimensional finite element model is established. Electromagnetic characteristics that focus on the high integration, low loss and high reliability are discussed and validated comprehensively. Finally, a favorable controllability of radial suspension forces are verified using finite-element analysis and some experimental results.

Modeling Based on Exact Segmentation of Magnetic Field for a Centripetal Force Type-Magnetic Bearing

In this article, to overcome the shortcomings of the existing modeling methods, a new mathematical modeling method of suspension force for a centripetal force type-magnetic bearing is proposed to get more accurate results. The proposed modeling method is based on exact segmentation of magnetic field. It solves especially the key problems such as the accurate calculation of fringing flux and the magnetic flux-leakage coefficient. To illustrate the improvement of the new model, some model validation and performance experiments are designed and implemented. The better model validation results prove the accuracy of the established model and the theoretical analysis results. The better performance tests results prove that the rotor based on the established model has stronger anti-interference.

Achieving anti-roll bar effect through air management in commercial vehicle pneumatic suspensions

ABSTRACTThis paper introduces the concept of managing air in commercial vehicle suspensions for reducing body roll. A conventional pneumatic suspension is re-designed to include higher-flow air hoses and dual levelling valves for improving the dynamic response of the suspension to the body roll, which commonly happens at relatively low frequencies. The improved air management allows air to get from the air tank to the airsprings quicker, and also changes the side-to-side suspension air pressure such that the suspension forces can more readily level the vehicle body, much in the same manner as an anti-roll bar (ARB). The results of a multi-domain simulation study in AMESim and TruckSim indicate that the proposed suspension configuration is capable of providing balanced airflow to the truck’s drive-axle suspensions, resulting in balanced suspension forces in response to single lane change and steady-state cornering steering maneuvers. The simulation results further indicate that a truck equipped with the reconfigured suspension experiences a uniform dynamic load sharing, smoother body motion (less roll angle), and improved handling and stability during steering maneuvers commonly occurring in commercial trucks during their intended use.

Passive suspension optimization of a quarter car using preview control with the spectral decomposition method

In this paper, control of a quarter car vehicle model with optimized passive suspension elements is presented. The vehicle is considered to travel on a rough road which is modeled as the power spectral density of the random road excitation given by integrated white noise that can be approximated by a deterministic step input. The weighted sum of the control force, suspension travel and road holding is minimized by using the optimal preview control law and the spectral decomposition method is used for obtaining the response. The parameters of a passive suspension system, namely spring stiffness and damping coefficient are optimally determined by the mean square equivalence of control force of the passive suspension to control force obtained by the stochastic optimal preview controller. The optimal parameters are also calculated by coordinating the passive suspension performance with the performance of the active preview control and the results show that the optimized passive system performance closely tracks the active system performance.

Performance optimization design and analysis of bearingless induction motor with different magnetic slot wedges

Abstract This paper investigates the application of using magnetic wedges in a semi-closed slot bearingless induction (BI) motor. In this strategy, the electrical loss of the motor can be reduced, improving the overall efficiency. At the same time, the temperature rise of the winding is reduced, and the vibration and noise levels are greatly depressed, which prolong the service life of the motor. First, the principle of BI motor operation is introduced. Second, the different magnetic permeability and geometric shape of the magnetic wedge are taken into consideration during the analysis the proposed BI motor. Then, the performance of BI motor with magnetic wedge is analyzed by finite element method. Finally, the results show that too high relative permeability materials can degrade the performance of the BI motor, thus, the use of suitable permeable magnetic wedge is reasonable. After adding the optimal magnetic wedge, the torque ripple, motor efficiency and the suspension force of the BI motor are optimized. The use of magnetic wedges has economic advantages and is of great significance for improving the performance of BI motors.