Saturation, cross-saturation, heating of the windings and magnets are nonlinear effects that can affect the measured machine parameters and performance. Because the machine parameters are used in the controller, inaccuracies in parameters will be reflected in the final controller. With parameter error, the controller will not operate as designed. Most studies justify the work of improving controllers and detecting faults by arguing that poor modeling and faults have a deleterious effect upon performance. They fail to completely define the effect on performance. The effect that controller modeling errors have upon performance is described for poor characterization, some minor faults, and the failure to include unmodeled dynamics. The sensitivity of performance to characterization is determined because of the vital nature of accurate parameter determination. Performance effects due to controller parameter error, saturation and other unmodeled dynamics are calculated to justify controller improvements, detailed characterization techniques and fault detection.
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