A Complex-Vector Resolver-To-Digital Conversion System with Prestage Systematic Error Mitigation

As a position sensor, the resolver system is widely used in robotic spindle machines to provide precise rotor angle, in which the complex-vector resolver-to-digital conversion (RDC) system is promising for its high accuracy under high speed. In addition, the systematic errors in resolver output should also be mitigated in RDC system, and the errors are normally compensated after the envelope demodulation. However, the current systematic error mitigation is not suitable for the complex-vector envelope demodulation since the systematic errors in sine and cosine outputs are coupled during the demodulation. To solve this, a novel prestage systematic error mitigation system before envelope demodulation is proposed in this paper for complex-vector RDC system. The systematic errors are observed by the combination of synchronous sampling and least-square observer, which can diminish the influence of motional voltage in high speed. Then, the prestage sequential error compensation is performed to directly calibrate the resolver outputs before envelope demodulation. By the simulation verification, by adding systematic error mitigation, the complex-vector RDC system can effectively reduce the 0.3 rad (i.e., 97%) angle error.