Abstract

Background: The electromagnetic aircraft launch system helps the carrier aircraft accelerate take-off on a short distance on the flight deck. Linear motors are required to have high efficiency and thrust / volume ratio, as the actuator of the EMALS. In addition, linear motors were required to have the fluctuation of the thrust is as small as possible to prevent impact and overstress on the airborne equipment. The thrust performance and thrust fluctuation suppression of linear motors are the current research hotspots in the field of EMALS.

Objective: This paper proposes a multi-segment LPMSM to improve the efficiency of the system.

Methods: We design a decentralized primary structure based on the Autonomous Decentralized System (ADS) concept. Only the coils near the moving secondary are motivated during the launch process. The others could be released from being driven after the secondary slide over; this control will save energy.

Results: A multi-segment linear motor is proposed to improve the efficiency of the EMALS. This motor consists of two sections - the one with iron core for the low speed process and the one without iron core for the high speed process.

Conclusion: The normal direction component of the air gap magnetic flux density is much larger than that of the longitudinal component, and their values are 80-90% and 10-20%, respectively. For the normal direction component, it is mainly affected by the third, seventh, and ninth harmonics. The accelerating and energy test results show that, in the accelerating process, the efficiency of the linear motor can be more than 90%, and the acceleration is stable.

Keywords: Autonomous decentralized system, EMALS, finite element analysis, linear permanent magnet synchronous motor, motor efficiency, multi-segment redundancy.