Design And Essential Technologies Research Of A Novel Moving-magnet Linear Oscillatory Actuator With No Inner-stators

Linear oscillatory actuator(LOA)is an electromagnetic driving device which is able to achieve high reciprocating linear motions without intermediate conversion mechanism.It has the merits of simple structure,low noise,fast response and high efficiency,etc.The actuator has been widely used to drive refrigeration compressors,pumps,artificial hearts and shakers.The moving-magnet LOA has becoming more and more important in LOA areas due to its light mover mass,high resonant frequency and high thrust density.However,the key issues which restrict the development of LOA are complicated structure,difficulty in inner stator stacking and high production cost.A novel LOA with no inner-stators was proposed,and in-depth analysis of some key issues of it xwas carried out.The content of this paper is organized as following:(1)A novel LOA with no inner-stators was first proposedBy analyzing various topologies of the existing LOAs,a novel moving-magnet LOA with no inner-stators was first proposed.The novel topology has two symmetry"C" type external divided stators with separation distance,and the mover is set between two "C" type teeth.It has the characteristics of compact configuration,easy manufacture,little flux leakage,high electromagnetic thrust density and good thrust controllability.(2)Magnetic equivalent circuit modelling and 3D finite element analysis(FEA)The principle of the novel LOA with no inner-stators was analyzed,and the magnetic equivalent circuit model of it was established.Then the analytical expression of electromagnetic thrust and inductance were derived via virtual work method.3D parametric FEA model of the novel LOA was established to calculate the flux distribution and electromagnetic thrust.The effects of permanent magnet(PM)dimensions and other key parameters on the performance of the novel LOA were also analyzed.(3)The design methodology and multi-objective optimization of the novel LOAThe design methodology of the novel LOA was analyzed,and the design criteria of the critical parameters and analytic formulas were derived via magnetic equivalent circuit method and 3D FEA.In order to meet the requirements of relative maximum thrust and relative minimum volume,a novel multi-object optimization method by combining the response surface model(RSM)and quantum-behaved particle swarm optimization(QPSO)was proposed to optimize the PM dimensions.The novel optimization method overcomes the shorages of low accurary of equivalent magnetic circuit optimization model and low calculation efficiency of 3D magnetic field model calculations,and avoids the problem which the traditional particle swarm optimization(PSO)method may fall into local optimal solution.The FEA results validates the correctness of the optimized results.After optimization,the thrust of this novel actuator was increased by 6.2%,and its volume was decreased by 12.8%.(4)Resonant frequency characteristics analysis and equivalent mechanical resonant frequency tracking control of the novel LOABased on driving the compressor load,equivalent mathematical model including mechanical system and electromagnetic system was proposed.The resonant frequency characteristics of this actuator was analyzed via vector methods,and the analytic formulas of critical performance such as efficiency and power factor were derived.A mechanical resonant frequency tracking control strategy based on improved perturbation and observation method was proposed.Simulation results showed that the improved algorithm is effective to accelerate the resonant frequency tracking velocity and reduce the power oscillations at the maximum power point.Research indicates that the mechanical resonant frequency tracking control under the variable load was realized and the efficiency was improved by the proposed algorithm.(5)The mover displacement self-sensing algorithm for the novel LOAThe mover displacement self-sensing algorithm for the novel LOA was established based on full-dimensional state observer.The simulation and experimental results showed that its mover displacement was estimated by calculating and processing its voltage and current under various frequency.The maximum absolute error of estimate stroke is 0.32mm,and the maximum relative error is 2.6%.An adaptive full-dimensional mover displacement observer was proposed based on equivalent resistance identification,and the adaptive law was deduced based on lyapunov.Research indicates that the proposed algorithm is able to restrain the observation errors caused by the changes in resistance parameters.(6)The protype experimental research of the novel LOAAn experimental prototype of the novel LOA was proposed,and the SPWM drive control system based on DSP was implemented.The experimental results of electrical performance verified the correctness of the design methodology,mathematical model and theoretical calculations.It also proved that this novel LOA has high research value and application prospects.