Patent ID: 6768284
Filing Date: 2004-07-27
Classification: H02M,H02P

Abstract:
A method for dynamically controlling induction machine regenerating energy flow and direct current bus voltage for an adjustable frequency drive system comprising a direct current bus and an inverter inputting the direct current bus, said inverter including a plurality of control inputs and a plurality of alternating current outputs, said method comprising:sensing a direct current voltage of said direct current bus; sensing a plurality of alternating currents at the alternating current outputs of said inverter; transforming said sensed alternating currents to a stationary current vector; converting a voltage value and a frequency value to a stationary voltage vector and an angle; transforming the angle and said stationary current vector to a rotating current vector including a torque producing current component and a flux producing current component; determining a generating mode of said induction machine when said torque producing current component reverses polarity; employing the voltage value and the frequency value to limit the direct current voltage of said direct current bus at a predetermined threshold responsive to said generating mode of said induction machine; determining a voltage difference between the direct current voltage of said direct current bus and the predetermined threshold; employing a compensation modulator to compensate the voltage difference and provide a compensated voltage difference; applying the voltage difference to a first algorithm having a first gain and a first output quantity in the generating mode; applying the compensated voltage difference to second and third algorithms having second and third gains and second and third output quantities, respectively, in the generating mode; providing an intermediate frequency from a set frequency and the first output quantity; adding the second output quantity to the intermediate frequency to provide a change frequency value; employing the third output quantity as a change voltage value; calculating the voltage value as the sum of a set voltage value and the change voltage value, and calculating the frequency value as the sum of a set frequency value and the chance frequency value; and converting the stationary voltage vector and the angle to pulse width modulated control signals for the control inputs of said inverter.