Experimental Implementation of PLL for Free-Piston Engine Application

Linear generators use linear motion to produce electricity, whereas conventional rotary generators use rotary motion to produce electricity. Their alternative configuration gives them superiority in system efficiency and reliability over their traditional counterpart. Incorporating the linear alternator in a free-piston engine system to utilize the linear motion has been studied in the past. This paper presents an implementation and instrumentation of a control technique for a single-phase tubular permanent magnet linear alternator in a Free Piston Engines (FPE) system. A minimum amount of mechanical energy is required to provide a minimal engine compression ratio to start the engine and electricity generation. To provide adequate energy, a start-up mechanism has been implemented to start running the engine by reaching the required displacement through the electrical linear motor. The technique has been implemented and tested on a real machine, software and hardware implementations are described, and results are presented.