电磁发射用直线电机及其控制技术综述

Review on Linear Motor for Electromagnetic Launch and Its Control Technology

电磁发射用直线电机是电磁发射系统的核心执行机构,为电磁发射提供驱动磁场和加速通道。近十年来,电磁发射用直线电机及其控制技术日趋成为直线电机领域较为热点的研究方向。该文归纳了电磁发射用直线电机的特点和关键技术,综述了电磁发射用直线电机及其控制技术的研究现状,探讨了电磁发射用直线电机的发展趋势和应用前景,旨在为电磁发射用直线电机的后续研究提供方向引导。

Electromagnetic launch(EML)technology is an energy conversion technology that directly converts electromagnetic energy into instantaneous kinetic energy to launch a payload.It breaks through traditional launch methods'energy and speed limits,an inevitable way for future launch methods.A linear motor for EML is powered by a pulse power supply that launches over 100 m/s,which is the core actuator and provides a driving magnetic field and accelerating path.The linear motor is a new research direction derived from high-power linear motors with common problems such as higher thrust density,magnetic field saturation effect,and multi-level energy conversion.It also has the characteristics of traditional linear motors,such as end effect,edge effect,and phase impedance imbalance.Special issues of long primary segmented power supply,multi-stator coupling modeling,assignment alternating strategy,fault diagnosis,and disturbance-free operation need to be solved.In the last ten years,the linear motor and its control technology have become a hot research direction.The linear motor for EML comprises the multi-stator,multi-phase,and long primary structure,facing the magnetic field saturation and magnetic flux leakage problems It has a short-time pulse current working mode,requiring extremely high reliability,redundancy,maintainability,and long life.Like traditional linear motor technology,linear motor technology for EML also includes three aspects:motor body,motor control,and motor maintenance.However,the linear motor for EML faces special technical issues for working in special and extreme conditions.This paper introduces three key technologies:high-power linear motor design,long primary stator segmented power supply,and continuous emission thermal management.The research status of the three typical linear motors is reviewed:electromagnetic catapult motor,electromagnetic rail launch motor,and electromagnetic coil launch motor.This paper also summarizes the research status of linear motor control for EML,focusing on segmented power supply,thrust fluctuation suppression,fault diagnosis,and redundancy control.Segmented long primary causes the motor inductance imbalance,resulting in thrust fluctuation and degrading system performance.The solving methods are divided into two categories:modifying the end winding type to eliminate the pulsating magnetic field and controlling current to counter the thrust fluctuation caused by asymmetry.The sources of thrust fluctuations are structural factors,control factors,and other factors.Structural factors,such as cogging torque,end effect,magnetic field space harmonics,and phase imbalance,are optimized or compensated by changing motor topology.Meanwhile,control factors,such as segmented control,time-delay disturbance,parameter variation,and current ripple,can only be suppressed through control strategies,feed-forward control,and other measures.The structure of N primaries(N≥2)sharing just one secondary can be adopted to further enhance the thrust density and reliability of a double-sided linear induction motor.If one primary fails,the residual N-1 primaries can accomplish the scheduled target,exhibiting solid redundancy.Linear motors for EML work in extreme conditions and have basic characteristics,including strong coupling,high transient,high stress,high-speed motion,and pulse operation.Limited by the weight,volume,material property,and manufacturing technology of the EML device,technical bottleneck solutions mainly rely on engineering technology methods.With the rapid development of high-speed maglev and EML technology,linear motors for EML will become a particular research category,and the related technologies will receive continuous breakthroughs and improvements.Furthermore,this paper proposes the development trend,such as hybrid excitation and superconducting coil technology,mover lightweight technology,vacuum launch tube and suspension technology,high-performance material application,and position sensorless control,providing a referencefor subsequent research.