A demodulation technique for spindle rotor position detection

This paper presents a demodulation technique for amplitude modulated rotor position signals of resolver using synchronous integration approach. The technique requires oversampling of the modulated signals. The integration period is determined from zero crossing detection of the modulated quadrature rotor position signals. The actual envelopes of the signal waveforms are then obtained by utilizing the phase relationship of the integrated waveforms with the delayed carrier signal. Due to integration, the noise and disturbance effects are averaged out and the achievable accuracy is improved without the need of applying filters. The method is developed from exploration of detecting the HDD spindle rotor position in high resolution. The effectiveness of the proposed signal processing method is demonstrated with the simulations and experiments, and the results are also compared to the other methods.