electrical cycle while offset errors in the measurement will
create a harmonic twice per electrical cycle [4]. The spectrum
of torque ripple shown in Figure 1 is from a motor with ten
electrical cycles per mechanical revolution. Current error is
responsible for the 10th harmonic and part of the 20th
harmonic seen. Similarly, any deviation in the assumed
sinusoidal shape of the back-EMF will result in a deviation in
the output torque [5].