Speed Error Mitigation for a DSP-Based Resolver-to-Digital Converter Using Auto-Tuning Filters

Modern resolver-to-digital converters (RDC) are typically implemented using DSP techniques to reduce hardware footprint and enhanced system accuracy. However, in such implementations, both resolver sensor and ADC channel unbalances introduce significant errors particularly in the speed output of the tracking loop. The frequency spectrum of the output error is variable depending on the resolver mechanical velocity. This paper presents the design of an auto-tuning output filter based on the interpolation of pre-computed filters for a DSP-based RDC with a type-II tracking loop. A fourth-order peak and a second-order high pass filter are designed and tested for an experimental RDC. The experimental results demonstrate significant reduction of the peak-to-peak error in the estimated speed

MITIGATION OF DC-LINK VOLTAGE OSCILLATIONS CAUSED BY RESOLVER ERROR IN AN ELECTRIC VEHICLE DRIVETRAIN

Resolvers are commonly used to measure the rotor position in motor drive applica

Position sensing in brake-by-wire callipers using resolvers

Recent designs for brake-by-wire systems use "resolvers" to provide accurate and continuous measurements for the absolute position and speed of the rotor of the electric actuators in brake callipers (permanent magnet DC motors). Resolvers are absolute-angle transducers that are integrated with estimator modules called "angle tracking observer" and together they provide position and speed measurements. Current designs for angle-tracking observers are unstable in applications with high acceleration and/or speed. In this paper, we introduce a new angle-tracking observer in which a closed-loop linear time-invariant (LTI) observer is integrated with a quadrature encoder. Finite-gain stability of the proposed design and its robustness to three different kinds of parameter variations are proven based on theorems of input-output stability in nonlinear control theory. In our experiments, we examined the performance of our observer and two other methods (a well-known LTI observer and an extended Kalman filter) to estimate the position and speed of a brake-by-wire actuator. The results show that because of the very high speed and acceleration of the actuator in this application, the LTI observer and Kalman filter cannot track the rotor position and diverge. In contrast, with a properly designed open-loop transfer function and selecting a suitable switching threshold, our proposed angle-tracking observer is stable and highly accurate in a brake-by-wire applicatio