On-engine Electrical Power Generation

Orbital Traction has developed a new on-engine electrical generator system based on a Constant Velocity Generator (CVG).  The CVG will replace or supplement the existing alternator in the same or smaller package providing increased power across the operating range. Unlike a traditional alternator configuration, the CVG will continuously maintain the ideal operating speed and power output of the generator regardless of the engine speed. Traditional alternators tend to be oversized to produce enough power to meet the maximum electrical vehicle load at engine idle.  The CVG will provide a compact and lightweight power generation system to power electrical loads on a vehicle without adding addition weight beyond that of an alternator.

The CVG design is based upon two recently developed innovative core technologies: an adjustable speed drive (ASD), and a high-performance generator (HPG). Innovative generators that provide a step-change improvement in efficiency and power density have been introduced to the market.  The power output of these generators is speed dependent, however, resulting in limited power output for engine applications.  The ASD provides constant speed for the generator through the range of engine speeds allowing optimal performance, improved overall system efficiency and reduced fuel consumption.

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Input Speed Management:  The ASD will independently control the generator speed across a typical engine speed range of 750-4,500 RPM.  The HPG generator and electronics are significantly simplified, and efficiency is increased by maintaining a constant input speed.  Orbital’s ASD allows for up to a 950% ratio range which can maintain constant output speeds over the range of input speeds from 800 to 6000 RPM.    As the engine accelerates the ASD ratio changes to maintain a constant output speed over time.  The ASD system uses an output speed sensor as feedback to the control system which adjusts the ASD setpoint using a control loop set to a specific speed.