Adjustable speed generator systems - an emerging technology for efficient electrical energy generation

The paper presents adjustable speed generation systems providing high quality output AC standard voltage independently to type of load and saving primary energy. The energy saving is result of speed control in a range of high efficiency of the engine. The new adjustable speed generation systems can be driven by any internal or external combustion engine but presented examples are related mostly to diesel engine. The prime mover is driving a newly designed and built axial flux shaftless and bearingless permanent magnet generator, which supplies power electronic converter acting as universal AC power source with single or three phase output. Speed of the prime mover is adjusted to meet load demand by real time load measurement. Thus the power electronics converter decouples the generator and load and then speed of the generator is not related to frequency of the output voltage. Therefore such a system has degree of freedom related to speed. There are two basic topologies providing decoupled generation first called ldquodecoupled by topologyrdquo and second called ldquodecoupled by control and topologyrdquo. Systems are fully controlled and provide high quality output power. Theory and results of tests of both decupled systems confirm their performances.