All-digital resolver-digital converter algorithm based on principle of Δ∑ modulation

In order to achieve an all-digital resolver-digital converter (RDC) with low-cost and high-precision, the analog signal of resolver was converted to high-resolution digital signal by Δ∑ analog to digital converter (Δ∑ADC) based on oversampling principle. And the carrier signal in the digital signal was removed through the sinusoidal filter which has periodic notch characteristics. The phase lag which is caused in the system loop was compensated by the method of delay synchronization correction. The angle and speed signals was calculated in real time through a closed loop angle tracking algorithm which is constituted by a digital phase-locked loop. Experimental results verify the proposed all digital RDC implements resolver to digital conversion with high precision high dynamic and static characteristics, relying on the high performance of Δ∑ADC and rapid algorithm of field programmable gate array (FPGA). And the system cost is reduced.