A Demodulation Technique for Spindle Rotor Position Detection With Resolver

This paper presents a demodulation technique for amplitude modulated signals from a resolver based on amplitude detection of a sinusoidal waveform by numerical integration. The proposed technique performs synchronous integration on output signals of the resolver. The integration period is determined from zero crossing detection of the same output signals. The actual envelopes of the signal waveforms are 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 applying filters. The method is developed from exploration of detecting HDD spindle rotor position in high resolution. The effectiveness of the proposed technique is demonstrated with the simulations and compared to the other methods. Experimental results are also provided to support the proposed method.