Selection of Position Sensor Resolution for Variable Speed Drives Based on Quantization Harmonic Rejection

Variable speed drive operation at low speeds is critical due to the detrimental impact of quantization harmonics arising from the finite resolution of the position sensor. This effect is exacerbated in motor drives equipped with low-resolution, i.e. low-cost, position sensors. This study presents a methodology for determining the minimum sensor resolution required to satisfy motor drive performance at the lowest operating speed, based on quantization harmonic rejection. A state of the art two-degree-of-freedom proportional-integral speed controller is employed, along with vector-tracking-observer-based speed estimation. The findings of this study provide valuable guidance for motor drive designers in selecting the most appropriate rotor position sensor for each specific application. The feasibility and effectiveness of the proposed approach are validated through experimental tests on a 3.6kW permanent magnet synchronous motor drive.