Feedback Linearization and Maximum Torque per Ampere Control Methods of Cup Rotor Permanent-Magnet Doubly Fed Machine

This paper establishes the state-space model of the cup rotor permanent-magnet doubly fed machine in the synchronous reference frame. The feedback-linearization control method is used to realize the decoupling control of flux and torque. Then, the upper and lower load torque boundaries are solved. Furthermore, to minimize the stator current magnitude of the control machine under a certain torque, the maximum torque per ampere (MTPA) control is derived. Finally, simulation results demonstrate the good decoupling performance of the feedback-linearization control method and the correctness of the load torque boundaries. In addition, the effectiveness and robustness of the proposed control methods are also demonstrated.

Nonlinear Feedback Linearization Control for Wind Generators in Hybrid Wind Energy Conversion Systems

This paper deals with the optimal power extraction of wind generators in hybrid wind energy conversion systems. The proposed control technique is the nonlinear exact feedback linearization which is able to give satisfactory performances over a broad spectrum of operating points. The main contribution of the paper is the successful dealing with the most challenging task in the design of nonlinear feedback linearization controllers for wind energy conversion systems, which is the transform and manipulation of state-dependent high-order nonlinear power coefficients presented in wind turbines. In other words, this paper addresses the full-order highly nonlinear power coefficients functions instead of using approximated low-order functions as in previous works in literature. The obtained nonlinear controller is able to cope with the time-varying nature of wind turbines and maintain the optimal power conversion points. Moreover the nonlinear feedback linearization control performance is also compared to that of traditional perturbation and observation based maximum power point tracking and classical PI control. The numerical simulation outcomes show that the proposed nonlinear controller outperform those two traditional controllers in terms of maximum gained power and transient specifications.

Lyapunov-Function-Based Feedback Linearization Control Strategy of Modular Multilevel Converter–Bidirectional DC–DC Converter for Vessel Integrated Power Systems

The modular multilevel converter–bidirectional DC–DC converter (MMC–BDC) has been proposed to be utilized in the vessel integrated power system to interconnect the medium voltage bus and the distributed energy storage elements. In the shipboard applications, MMC–BDC faces unbalanced sub-module power operation because of the inconsistent state-of-charge (SOC) of the energy storage elements. Researchers have investigated into the unbalanced operation principle of MMC–BDC and proposed some unbalanced operation control strategies, but these traditional strategies do not perform well in both aspects of operating range and efficiency. Therefore, this paper proposes a novel Lyapunov-function-based feedback linearization control strategy for the independent sub-module voltage control of MMC–BDC, which not only shows wide unbalanced operation range and high efficiency, but also realizes the decoupling and symmetrical control of the sub-module capacitor voltages.