Double-reference pulse-width modulation for torque minimization of AC machines

A method, comprising:

• generating a base reference signal for each of three or more reference phases;
• determining a maximum reference (max) and a minimum reference (min) based on the base reference signal generated for each of the three or more reference phases;
• calculating a reference sum of the maximum reference and the minimum reference;
• generating a first offset by calculating the first offset to be 1−max when the reference sum is positive and −1−min when the reference sum is negative;
• generating a second offset by calculating the second offset to be −1−min when the reference sum is positive and 1−max when the reference sum is negative;
• for each of the three or more reference phases, performing the following, to obtain a set of multi-level pulse-width modulation (PWM) control signals:
• generating an upper reference by adding the first offset to the base reference signal when the signal is positive and adding the second offset when the signal is negative;
• generating a lower reference by adding the second offset to the base reference signal when the signal is positive and adding the first offset when the signal is negative;
• comparing the upper reference to a triangular upper carrier signal to generate an upper PWM output;
• comparing the lower reference to a triangular lower carrier signal to generate a lower PWM output;
• and
• combining the upper PWM output and lower PWM output to generate a multi-level PWM control signal for the respective reference phase that is comprised in the set of multi-level PWM control signals;
• and
• outputting the set of multi-level PWM control signals generated for the three or more reference phases to a multi-level power converter.