Abstract: A Stirling machine comprising a reciprocating power piston with a power magnet, and a stator having a coil electromagnetically coupled to the power magnet. At least one spring magnet is arranged to provide an axial centring force on the piston. The spring magnet is fixed with respect to the stator.

Abstract: A Stirling engine (1) includes a reciprocating piston which drives an alternator to provide an electrical output (7). The current signal (7) is measured by a current monitor (60) and a fast Fourier Transform value is produced. The FFT of the current signal (7) has been found to be directly related to the stability of operation of the Stirling engine. As harmonic peaks in the FFT increase, this indicates that the stroke length of the piston is approaching or exceeding a safe maximum. Correction action, such as a reduction in heat to the Stirling engine, can be taken in consequence. A variety of stroke length detectors (110) are also disclosed, for use in combination with, or separately from, the FFT analysis of the current signal (7). Optical and mechanical switches and analogue sensors are disclosed, along with an accelerometer mounted upon the casing of the Stirling engine.

Abstract: A magnetic assembly for a linear electromechanical machine, the assembly comprising an annular support centered on an axis of reciprocation of the machine. A magnet assembly is attached to the annular support. The magnet assembly comprises at least one annular part which is substantially magnetic. The annular part has at least one non-conductive portion in a substantially radial plane and extending at least half of the way through the wall of the annulus.

Abstract: A Stirling engine includes a reciprocating piston which drives an alternator to provide an electrical output. The current signal is measured by a current monitor and a fast Fourier Transform value is produced. The FFT of the current signal has been found to be directly related to the stability of operation of the Stirling engine. As harmonic peaks in the FFT increase, this indicates that the stroke length of the piston is approaching or exceeding a safe maximum. Correction action, such as a reduction in heat to the Stirling engine, can be taken in consequence. A variety of stroke length detectors are also disclosed, for use in combination with, or separately from, the FFT analysis of the current signal. Optical and mechanical switches and analogue sensors are disclosed, along with an accelerometer mounted upon the casing of the Stirling engine.

Abstract: The present invention provides a connector arrangement operative to connect a prime mover driven alternator to an alternating current circuit with an existing alternating current. For example, the connector arrangement may be used to connect an alternator driven by a Stirling engine to an alternating current mains electricity supply. The connector arrangement includes a circuit with an adjustable resonant frequency, adjustable between a first resonant frequency tuned to an initial operating frequency of the prime mover and a second resonant frequency detuned to the initial operating frequency. This adjustable resonant frequency is beneficial as it allows operation to be tailored to the exact operating conditions of the prime mover that is likely to have its own resonant frequency that may vary according to its operating condition.