Feedback Linearization Direct Torque Control With Zero-Sequence Current Regulation for DC-Biased VRM Drives

A feedback linearization direct torque control (FL-DTC) scheme with the ability of regulating zero-sequence current is proposed for the dc-biased vernier reluctance machines (DC-VRMs) to improve the steady and dynamic performance of drive system. First, an accurate original nonlinear model of DC-VRM is analyzed in synchronous rotating reference frame with three variables (i.e., the electromagnetic torque, the stator flux, and zero-sequence current). The saturation of self-inductance is considered to ensure the accuracy of model under different load. The virtual 0-axis flux ψ₀ is first defined in this article. Then, an FL-DTC scheme with zero-sequence current regulation is proposed to improve torque and flux ripple and dynamic response performance. The system stability is verified by the Lyapunov theory. Finally, comparative experiments to conventional PI-based SVM-DTC scheme in steady state and dynamic process are carried out. The advantages of the proposed method are verified, including high control accuracy of torque and flux, fast dynamic response to load change and speed reversal, outstanding low-speed range performance, and strong robustness to parameter uncertainties.