Fault diagnosis of linear electric generators for thermoacoustic machines

Energy generation and its optimal use are key issues nowadays. In this framework the use of cogeneration (CHP) or trigeneration (CHCP) is an attractive solution towards higher system efficiency. Traditional thermal machines are used as a prime mover in a CHP/CHCP plant. Recently novel technologies were investigated for prime mover and cooler. Among them thermoacoustics is attractive as it allows to embed a prime mover, a cooler and an alternator in a single machine. Moreover, it features reduced maintenance cost as it requires no moving parts but the electric alternator. The design of an efficient electric alternator is one of the major challenge, as it must convert into electricity a small linear displacement of the mover at high frequency. The latter is a critical item in terms of diagnostics also. Here the fault diagnosis of a thermoacoustic generator is investigated, where the major defects are ageing or fatigue of the spring used to center and sustain the mover of electric generator. The fault diagnosis is based on the non invasive analysis of electric signals at the generator terminal. The paper also deals with post fault strategies.