Method and compensation modulator for dynamically controlling induction machine regenerating energy flow and direct current bus voltage for an adjustable frequency drive system

An adjustable frequency drive system comprising:

• a three-phase induction machine;
• and
• an adjustable frequency drive comprising:
• a converter including a plurality of alternating current inputs and a direct current output having a first node and a second node;
• a capacitor electrically connected between the first and second nodes of said direct current output;
• an inverter including a direct current input, a plurality of switches, a plurality of control inputs, and a plurality of alternating current outputs, said direct current input electrically connected to said direct current output, said alternating current outputs adapted to electrically connect to said alternating current inputs of said induction machine;
• each of said switches electrically connected between one of the first and second nodes and one of the alternating current outputs of said inverter, each of said control inputs controlling one of said switches;
• a voltage sensor sensing a direct current voltage at the direct current output of said converter and outputting a sensed voltage value;
• a plurality of current sensors sensing a plurality of alternating currents at the alternating current outputs of said inverter and outputting a plurality of sensed current values;
• and
• a processor comprising:
• a plurality of inputs for said sensed current values and said sensed voltage value,
• a plurality of outputs for the control inputs of said inverter,
• a Clarke Transform module transforming said sensed current values to a stationary current vector,
• a space vector module including a plurality of inputs and a plurality of outputs, the inputs of said space vector module comprising a set voltage value, a set frequency value, a change voltage value, and a change frequency value, the outputs of said space vector module comprising a stationary voltage vector and an angle,
• a pulse width modulation (PWM) module including a plurality of inputs and a plurality of outputs, the inputs of said PWM module comprising the stationary voltage vector and the angle, the outputs of said pulse width modulation module providing the control inputs of said inverter,
• a Park Transform module transforming the angle and said stationary current vector to a rotating current vector, and
• a regeneration override module comprising a plurality of inputs and a plurality of outputs, the inputs of said regeneration override module comprising the sensed voltage value and said rotating current vector, the outputs of said regeneration override module comprising the change voltage value and the change frequency value, said regeneration override module dynamically controlling regenerating energy flow from the induction machine to the direct current output of said converter, wherein said regeneration override module includes means for determining a voltage difference between the sensed voltage value and a predetermined threshold, means for compensating the voltage difference and providing a compensated voltage difference, means for providing a first output quantity in the generating mode from the voltage difference and a first gain, means for providing a second output quantity in the generating mode from the compensated voltage difference and a second gain, and means for providing a third output quantity in the generating mode from the compensated voltage difference and a third gain.