Modular auxiliary power unit assembly for an electric vehicle
First Claim
1. A propulsion system comprising:
- an electric motor;
an energy storage unit configured to supply a primary power to the electric motor; and
a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit, each of the plurality of APUs comprising;
a free-piston engine configured to generate a mechanical output;
a linear generator configured to transform the mechanical output to an electrical power; and
a controller configured to;
receive a power command from the at least one of the electric motor and the energy storage unit;
determine an amount of secondary power needed to meet the power command; and
selectively activate a number of the plurality of APUs to generate the needed amount of secondary power, wherein selectively activating a number of the plurality of APUs comprises;
individually operating each of the plurality of APUs in one of an on condition or an off condition based on the needed amount of secondary power; and
operating each of the plurality of APUs in the on condition above a minimum efficiency threshold, including selectively operating each of the plurality of APUs in the on condition at various speeds at less than a full power-generating capacity and generating an equal fraction of the secondary power.
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Accused Products
Abstract
A system and method for a propulsion system includes an electric motor and an energy storage unit configured to supply a primary power to the electric motor. The propulsion system also includes a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit. Each of the plurality of APUs includes a free-piston engine configured to generate a mechanical output, a linear generator configured to transform the mechanical output to an electrical power, and a controller. The controller receives a power command from the electric motor and/or the energy storage unit, determines an amount of secondary power needed to meet the power command, and selectively activates a number of the plurality of APUs to generate the needed amount of secondary power.
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Citations
12 Claims
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1. A propulsion system comprising:
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an electric motor; an energy storage unit configured to supply a primary power to the electric motor; and a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit, each of the plurality of APUs comprising; a free-piston engine configured to generate a mechanical output; a linear generator configured to transform the mechanical output to an electrical power; and a controller configured to; receive a power command from the at least one of the electric motor and the energy storage unit; determine an amount of secondary power needed to meet the power command; and selectively activate a number of the plurality of APUs to generate the needed amount of secondary power, wherein selectively activating a number of the plurality of APUs comprises; individually operating each of the plurality of APUs in one of an on condition or an off condition based on the needed amount of secondary power; and operating each of the plurality of APUs in the on condition above a minimum efficiency threshold, including selectively operating each of the plurality of APUs in the on condition at various speeds at less than a full power-generating capacity and generating an equal fraction of the secondary power. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A propulsion system comprising:
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an electric motor; an energy storage device; a DC link electrically connecting the electric motor and the energy storage device; a plurality of crankshaft-less engine and linear generator combinations electrically connected to the DC link; and a controller configured to; determine a power requirement of the electric motor and energy storage device; and selectively activate a number of the plurality of crankshaft-less engine and linear generator combinations to provide power to the DC link based on the power requirement; wherein each of the selectively activated crankshaft-less engine and linear generator combinations is operated above a minimum efficiency threshold but at less than a maximum power-generating capacity at various speeds and generating an equal fraction of the power requirement. - View Dependent Claims (10, 11, 12)
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Specification