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The conventional Diesel cycles engine is now approaching the practical limits of efficiency. The recuperated split cycle engine is an alternative cycle with the potential to achieve higher efficiencies than could be achieved using a conventional engine cycle. In a split cycle engine, the compression and combustion strokes are performed in separate chambers. This enables direct cooling of the compression cylinder reducing compression work, intra cycle heat recovery and low heat rejection expansion. Previously reported analysis has shown that brake efficiencies approaching 60% are attainable, representing a 33% improvement over current advanced heavy duty diesel engine. However, the achievement of complete, stable, compression ignited combustion has remained elusive to date.

The Recuperated Split Cycle Engine is a new type of ICE, offering a step change in efficiency and tailpipe emissions. It targets the heavy duty, long-haul sector (trucks, off-highway, rail, shipping), where electrification is most challenging, and distributed generation, where capacity is required to support rising electrification. The engine separates cold (induction, compression) and hot (combustion, expansion) parts of the cycle; waste exhaust heat is recovered between them via a recuperator, as in a recuperated gas turbine. Recent research presented at this conference [1] shows that the sonic airflows seen in the induction event give rise to extraordinary fuel mixing and clean, cool combustion, with potential for after-treated emission levels between SULEV and zero-impact (either unmeasurable or below ambient).

A duplex 3-phase (6-phase with 2 star-points) eMachine and associated inverter, including the development of the control algorithm, for a P2 hybrid vehicle was developed. The requirements, relating to power and duty cycle, flow down from the vehicle to the eMachine: these are shown and design issues relating to the use of a 48V system presented. The focus on low cost, compact solutions runs through the work. The inverter is rated at 25 kW to drive an interior permanent magnet eMachine, supplied by a 48V dc-link. The focus of the work presented in this paper is the inverter controller development and powertrain sizing. The test results of the eMachine with the inverter are presented to show the drive system operating the 6-phase current controller and inverter.