A novel linear induction motor for electromagnetic aircraft launch system
A variable pole pitch linear induction motor (VPPLIM) is proposed as a new member of the family of electromagnetic aircraft launch system (EMALS). With proper designing of the variation of the pole pitch, the VPPLIM could accelerate the aircraft almost uniformly at the condition of usual AC supply, avoiding use of large scale power electronics converters. The special considerations in the design of VPPLIM, such as the structure topology and the variation of the pole pitch are discussed detailedly in the paper. The acceleration performance of the VPPLIM fed by a constant voltage constant frequency supply is analyzed by means of the quasi-steady-state 2D magnetic field model and the difference model of mover's dynamics. A two stage method is proposed to simulate the acceleration performance of the VPPLIM based on a 2D thrust table of the motor achieved by finite element method (FEM). The calculated features of the prototype VPPLIM consist well with those expected for EMALS.
A Maximum Constant Boost Quasi Z Source Invertor with Third Harmonic Injection for Linear Induction Motors
- Three phase voltage linear induction motors (LIMs) are emerging as a reliable means of providing both fast transport solutions and significant amount of linear thrust. However, conventional Voltage Source Invertor (VSI) and Current Source Invertor (CSI) motor drives applied to LIMs suffer from the generation of harmonic currents from the nonlinear nature of the LIM. This paper presents an improved Quasi-Z-Source Inverter (QZSI) for a linear induction motor (LIM) whose controller has been built, and its simulated results. The proposed QZSI controller herein for a LIM will injects uniformly spaced shoot through states, and promises a high output voltage gain and reduced THD.
Ignition and burning rates of segregated waste combustion in packed beds.
Recent developments in national recycling and re-use programmes for municipal waste have led to segregation of an increasing proportion of waste to enhance material recovery. Several of the segregated streams contain materials that can not viably be re-used or recycled but can be used for energy recovery. In this study, the combustion of cardboard and waste wood was investigated in a small-scale packed bed reactor in order to provide fundamental data for the design/operation of moving bed furnaces. Key parameters of combustion including the ignition and burning rates were evaluated for various air flowrates and compared to the modelling results. Two successive stages of combustion were identified for both samples: the propagation of ignition front into the bed and combustion of the fuel above the ignition front. The burning rate of cardboard reached a peak of about 300 kg/m(2)h at the air flowrate of 936 kg/m(2)h and decreased at higher air flowrates. For waste wood, both the ignition and burning rates increased in the tested range of the air flowrate up to 702 kg/m(2)h, of which the values were very close to those for the cardboard. The model prediction was in good agreement with the test results for waste wood. However, the burning rate for cardboard was under-predicted due to strongly irregular shapes of the fuel.