Abstract: A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Abstract: A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Abstract: A method for dynamically controlling regenerating energy flow and direct current bus voltage for an adjustable frequency drive system includes sensing a direct current voltage of a direct current bus; and sensing a plurality of alternating currents at outputs of an inverter. The sensed alternating currents are transformed to a stationary current vector. Voltage and frequency values are converted to a stationary voltage vector and an angle. The angle and the stationary current vector are transformed to a rotating current vector including torque and flux producing current components. An induction machine generating mode is determined when the torque producing current component reverses polarity. The voltage and frequency values limit the direct current voltage of the direct current bus at a predetermined threshold responsive to the generating mode. The stationary voltage vector and the angle are converted to pulse width modulated control inputs of the inverter.

Abstract: A method for dynamically controlling regenerating energy flow and direct current bus voltage for an adjustable frequency drive system includes sensing a direct current voltage of a direct current bus; and sensing a plurality of alternating currents at outputs of an inverter. The sensed alternating currents are transformed to a stationary current vector. Voltage and frequency values are converted to a stationary voltage vector and an angle. The angle and the stationary current vector are transformed to a rotating current vector including torque and flux producing current components. An induction machine generating mode is determined when the torque producing current component reverses polarity. The voltage and frequency values limit the direct current voltage of the direct current bus at a predetermined threshold responsive to the generating mode. The stationary voltage vector and the angle are converted to pulse width modulated control inputs of the inverter.