Development of Resonating Oscillating Linear Engine Alternator; Instrumentation and Control

Abstract

Development of Resonating Oscillating Linear Engine Alternator; Instrumentation and Control Fereshteh Mahmudzadeh The Oscillating Linear Engine and Alternator (OLEA) machine is a micro power generator that operates on natural gas. The OLEA is a permanent magnet linear tubular electric machine. It is driven by a two-stroke, free-piston internal combustion engine. The WVU team is developing the OLEA, which is a 1 KW electricity generator with high efficiency, long life, compact size, and low cost for residential and commercial applications. This research focuses on implementing and testing the instrumentation and control of a linear tubular permanent magnet alternator combined with a two-stroke, free-piston internal combustion engine into a single unit. A start-up mechanism has been implemented to start running the engine. Afterward, the controller regulates the engine performance by adjusting the combustion timings. In order to start the engine and run the machine in generating mode, enough mechanical energy is required to be transferred to the system to provide minimal engine compression ratio. The alternator gate-driving signal is supposed to be synchronized to the translator movements to achieve the maximum transfer of energy and start the engine. Thus, a start-up mechanism is essential to acquire the preferred alignment of the driving voltage to the motion signal. The OLEA machine is controlled by synchronizing the gate-driving signal with the translator position in the motoring mode. The control strategy during the machine start-up involves using a software-based Phase Locked Loop (PLL) system. A Linear Magnetic Hall Effect sensor is employed to collect the position data for the OLEA system. At the same time, the entire control procedure, including the motoring and generating modes, is designed according to real-time position information received by the position sensor. Engine control in generating mode is accomplished by the ignition signal in real-time, according to the current position of the alternator. Similar to the startup, the engine ignition signal is generated by the PLL approach. The phase excitation voltage signals for startup and ignition

Design, Modeling and Optimization of Reciprocating Tubular Permanent Magnet Linear Generators for Free Piston Engine Applications

“…A phase locked loop (PLL) technique was used to control the PMLG system as a motor. Details on the PLL technique used for the PMLG system is detailed in [98]. The H bridge inverter that is used for the PMLG system consists of four IGBTs to provide pulse signals to the PMLG system in both directions.…”

Development of Resonating Tubular Oscillating Linear Alternator and Engine; System Design and Modeling

“…Much of the early design work for the linear engine and alternator system at WVU was already completed for the first prototype (alpha machine) by the team when I came on board. The preliminary alternator design (alpha design) was already completed with major credit going to Jayaram Subramaniam and Dr. Famouri and the inverter and position detection for starting of the linear engine by Feheshteh Mahmudzadeh Ghomi [7]. The complete construction, assembly, testing, and evaluation of the results of the alpha machine were necessary to establish a baseline of performance to allow construction of additional machines with well predicted performance.…”

“…Feng, et al have analyzed the combustion processes inside a free piston linear engine and compared them against a traditional rotary engine [17]. Figure 1: Cutaway View Linear Engine and Alternator [7] The linear engine and alternator system that is undergoing research at WVU is a resonant oscillating mass spring system. The construction of the alternator consists of a drum of axially programmed magnetic rings (referred hereinafter as the translator) sitting between spiral cut planar flexure springs with the magnetic drum inside of a stator of copper coils.…”