An Embedded Resolver-to-Digital Conversion Method Using Resonant Excitation and Quality-Driven Autotuning

Resolvers are widely used in safety-critical and harsh environments due to their robustness against temperature, vibration, and electromagnetic interference. Conventional resolver-to-digital converters (RDCs) often rely on monolithic integrated circuits (ICs) integrating excitation, demodulation, and tracking loops, which add cost and board footprint while limiting flexibility. This article presents a fully embedded RDC that eliminates dedicated RDC ICs by exploiting PWM and ADC resources of modern microcontrollers (MCUs). The method combines: 1) a GaN half-bridge resonant excitation engineered to align resolver sine/cosine peaks with ADC sample-and-hold instants; 2) differential 16-bit ADC acquisition with hardware PWM-ADC synchronization at sub-10-ns resolution; and 3) a software phase-locked loop (PLL) with quality-driven autotuning that minimizes the ripple of a monitoring function to optimize sampling timing and performs automatic gain/offset calibration. Experiments on a 1.1-kW PMSM test bench comparing the proposed method with a commercial RDC-IC channel show comparable or superior position/speed accuracy (ripple < 0:5%), finer velocity quantization, robust tracking during acceleration, and significant reductions in cost and PCB area. The results indicate that excitation engineering and metric-based autotuning are effective enablers for next-generation embedded resolver interfaces in electric drives.