Resonance Suppression for NIPMVM Based on Double-Pre-Warped Tustin Bi-Quad Filter

This article proposes a double-pre-warped Tustin bi-quad filter (DPT-BQF) to suppress mechanical resonance for non-contact integrated permanent magnet vernier motors (NIPMVMs). First, this article analyzes how conventional notch filters suffer from distortion in notch frequency, bandwidth, and depth when discretized with low-precision methods, which degrades filtering performance and weakens resonance suppression. To address this issue, the inherent limitations of the pre-warped Tustin discretization for BQFs are discussed. On this basis, a double pre-warped Tustin method is proposed by compensating for the bandwidth distortion, and its discretization performance is comprehensively evaluated. Furthermore, the principle, parameter design, and robustness range of the filter are deeply analyzed in the discrete domain. Finally, experimental validation on an NIPMVM test platform demonstrates the effectiveness and feasibility of the proposed method.