Online Torque-Flux Estimation-Based Nonlinear Torque and Flux Control Scheme of IPMSM Drive for Reduced Torque Ripples

In order to have direct and better control of reducing the torque/flux ripples of interior permanent magnet synchronous motor (IPMSM), this paper presents an online torque and flux estimation-based nonlinear torque and flux control (NTFC) scheme of IPMSM drive considering motor electromagnetic developed torque and stator air-gap flux linkage as virtual state variables. For conventional nonlinear controller, the d-q-axis currents (id, iq) are considered as state variables that indirectly controls the torque/flux which may not be suitable for high-performance drives. On the other hand, conventional direct torque and flux control (DTFC) scheme suffers from significant torque ripples. The proposed work overcomes the major drawback of both the conventional nonlinear and DTFC schemes through the significant reduction in torque ripples. Stability of the proposed drive is also demonstrated through Lyapunov's stability criterion and global asymptotic stability is assured through the application of criterion supported by Barbalat's lemma. Reduced torque ripples and robustness of the proposed NTFC scheme is validated through comparative simulation and experimental results with classical nonlinear controller and DTFC-based IPMSM drive. The proposed NTFC scheme achieves the lowest possible torque ripples in steady state at different operating conditions.