Robust estimator design for signal injection-based IPM synchronous machine drives

This paper analyzes the design choices taken when designing a carrier-signal-based self-sensing position and speed estimation strategy for IPM drives. The balance between the noise generation and the load disturbance rejection process is analyzed, since this balance is essential for robustness. An extended closed loop observer is introduced to improve robustness during load changes, and guidelines for choosing bandwidth for filters is given. A scalar current observer is essential for robust elimination of the fundamental component. An improved structure for the observer is presented and discussed, which improves the impact from transients from the BSF filters.