Patent ID: 7786691

Claim:
A method to regulate bus harmonics in a motor drive system connected to a power source, the method comprising the steps of: for each harmonic being regulated: transforming a bus feedback signal having at least one harmonic component due to the harmonic being regulated from a source reference frame to a harmonic reference frame of the harmonic being regulated to form a qd feedback signal, wherein the step of transforming the feedback signal includes the step of determining a harmonic angle of the harmonic being regulated, wherein the step of determining the harmonic angle comprises the steps of: resetting an output of an integrator upon detection of a zero crossing of a sine wave having the same frequency as the frequency of the power source; and setting the harmonic angle to the output of the integrator times the harmonic number of the harmonic being regulated; subtracting the qd feedback signal from a commanded value to form a qd signal; regulating the qd signal; transforming the regulated qd signal to a destination reference frame to form a compensation signal; and adding the compensation signal to a control signal to form a qd control signal to drive the harmonic being regulated towards the commanded value.