Abstract: An axial fan includes a rotatable fan blade assembly including a plurality of fan blades, and a plurality of permanent magnets affixed to the plurality of fan blades. A stationary guide channel is located radially outboard of the fan blade assembly. A plurality of field coils are located at the guide channel and are configured to drive rotation of the fan blade assembly via magnetic interaction with the plurality of permanent magnets when the plurality of field coils are sequentially energized. A method of operating an axial fan includes energizing a plurality of field coils, urging a fan blade assembly out of contact with the guide channel via magnetic interaction between the plurality of field coils and a plurality of permanent magnets located at the fan blade assembly, and sequentially pulsing the plurality of field coils thereby urging rotation of the fan blade assembly about an axis of rotation.

Abstract: An axial fan includes a rotatable fan blade assembly including a plurality of fan blades, and a plurality of permanent magnets affixed to the plurality of fan blades. A stationary guide channel is located radially outboard of the fan blade assembly. A plurality of field coils are located at the guide channel and are configured to drive rotation of the fan blade assembly via magnetic interaction with the plurality of permanent magnets when the plurality of field coils are sequentially energized. A method of operating an axial fan includes energizing a plurality of field coils, urging a fan blade assembly out of contact with the guide channel via magnetic interaction between the plurality of field coils and a plurality of permanent magnets located at the fan blade assembly, and sequentially pulsing the plurality of field coils thereby urging rotation of the fan blade assembly about an axis of rotation.

Abstract: A fast AC voltage detector includes a bridge rectifier connected to an AC power source, a threshold detector connected to an output of the bridge rectifier, a voltage isolation circuit connected to the threshold detector, a continuous voltage averager connected to an output of the voltage isolation circuit, and a Schmidt trigger connected to the continuous voltage averager. The Schmidt trigger is operable to output a first voltage level when a load is preset on said AC power source and a second voltage level when no load is present on said AC power source.

Abstract: A fast AC voltage detector includes a bridge rectifier connected to an AC power source, a threshold detector connected to an output of the bridge rectifier, a voltage isolation circuit connected to the threshold detector, a continuous voltage averager connected to an output of the voltage isolation circuit, and a Schmidt trigger connected to the continuous voltage averager.