Abstract: A multiphase current sensing method wherein the sum of the phase currents is zero including: sensing a.c. and/or d.c. currents in first and second phases; sensing a.c. current in a predetermined a.c. frequency range in a third phase; and combining the current sensed in the first and third phases and the second and third phases and determining a gain correction factor to be applied to the currents sensed in the first and second phases.

Abstract: A multiphase current sensing method wherein the sum of the phase currents is zero including: sensing a.c. and/or d.c. currents in first and second phases; sensing a.c. current in a predetermined a.c. frequency range in a third phase; and combining the current sensed in the first and third phases and the second and third phases and determining a gain correction factor to be applied to the currents sensed in the first and second phases.

Abstract: Indirect rotor resistance estimation for an AC induction motor is achieved by successively stepping the quadrature command to zero and the direct current command to a predetermined value causing the quadrature stator voltage to decay as a representation of rotor current decay; defining, in response to the decaying stator voltage reaching two spaced thresholds, a voltage/time difference, and retrieving from a storage device the rotor resistance associated with the voltage/time difference.

Abstract: Indirect rotor resistance estimation for an AC induction motor is achieved by successively stepping the quadrature command to zero and the direct current command to a predetermined value causing the quadrature stator voltage to decay as a representation of rotor current decay; defining, in response to the decaying stator voltage reaching two spaced thresholds, a voltage/time difference, and retrieving from a storage device the rotor resistance associated with the voltage/time difference.

Abstract: A contactor feedback and pre-charge circuit is disclosed that is capable of i) precharging a load to control the inrush of current, ii) discharging the load to eliminate the risk of shock due to capacitive charge, and iii) shutting the system down in the event the contactor unintentionally opens during operation.

Abstract: A voltage source inverter generating a poly phase AC signal is provided that includes an SVPWM controller. The controller is adapted to modify the switching pattern at low sine-wave frequencies creating a more even distribution of the conduction losses. The switching pattern periodically changes the sequence (or rotational sense) of the space vector components from clock-wise to counter-clock-wise direction, and vice-versa.

Abstract: A contactor feedback and pre-charge circuit is disclosed that is capable of i) precharging a load to control the inrush of current, ii) discharging the load to eliminate the risk of shock due to capacitive charge, and iii) shutting the system down in the event the contactor unintentionally opens during operation.

Abstract: A distributed generation system is disclosed that is capable of conditioning power from a utility grid, providing backup power in the event the utility grid fails, and exporting excess power to the utility grid. The system comprises an engine coupled to an asynchronous generator, an energy storage device, an engine controller capable of managing the engine and controlling its torque or speed or power, and an inverter for generating an AC output and also capable of controlling the frequency and voltage of the generator to match the frequency of a coupled utility grid.

Abstract: A controllable switching mechanism integrally housed within a motor to optimally couple the windings of an AC motor for improved torque-speed characteristics. The switching mechanism includes a plurality of double throw switches each with a first and second closed position. The first closed position results in connecting the windings of the AC motor in one configuration for improved torque at lower rotor speeds. The second closed position results in connecting the windings of the AC motor in another configuration for improved torque at higher speeds. The winding configurations may be wye for lower speeds and delta for higher speeds. An accompanying controller, based on various inputs, optimally senses the best time for switching between configurations and sends appropriate control signals to the switching mechanism housed with the AC motor.

Abstract: A voltage source inverter generating a poly phase AC signal is provided that includes an SVPWM controller. The controller is adapted to modify the switching pattern at low sine-wave frequencies creating a more even distribution of the conduction losses. The switching pattern periodically changes the sequence (or rotational sense) of the space vector components from clock-wise to counter-clock-wise direction, and vice-versa.

Abstract: A multiphase current sensing method wherein the sum of the phase currents is zero including: sensing a.c. and/or d.c. currents in first and second phases; sensing a.c. current in a predetermined a.c. frequency range in a third phase; and combining the current sensed in the first and third phases and the second and third phases and determining a gain correction factor to be applied to the currents sensed in the first and second phases.