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Wound field synchronous motors (WFSMs) without installing slip rings and brushes are drawing increasing attention in the electric vehicle (EV) propulsion systems. To ensure high control performance of the EV-WFSMs, this article proposes a robust maximum torque per ampere (MTPA) control strategy based on a series of new sliding mode (SM) inductance observers. First, after establishing the model of a WFSM based on capacitive coupling, the current control scheme is designed for the MTPA control. Second, to eliminate the impacts of the inductance uncertainties on the MTPA control, the SM mutual inductance observer, q-axis inductance observer, and d-axis inductance observer are designed, which need to be implemented one by one. Then, the Lyapunov stability criterion is used to analyze the stability conditions for the observers. Moreover, considering that the observers are achieved by using the offline inductance information provided by the suppliers, the robustness against parameter mismatch is innovatively discussed at length, and an analytical method that can avoid estimation errors is developed. The proposed inductance identification techniques and MTPA control method are verified by both simulation and experiments, which are conducted on a 580-W three-phase WFSM drive. [ABSTRACT FROM AUTHOR]

The nonlinearities and unmodeled dynamics inevitably degrade the quality and reliability of power conversion, and as a result, pose big challenges on higher-performance voltage stabilization of dc–dc buck converters. The stability of such power electronic equipment is further threatened when feeding the nonideal constant power loads (CPLs) because of the induced negative impedance specifications. In response to these challenges, the advanced regulatory and technological mechanisms associated with the converters require to be developed to efficiently implement these interface systems in the microgrid configuration. This article addresses an intelligent proportional-integral based on sliding mode (SM) observer to mitigate the destructive impedance instabilities of nonideal CPLs with time-varying nature in the ultralocal model sense. In particular, in the current article, an auxiliary deep deterministic policy gradient (DDPG) controller is adaptively developed to decrease the observer estimation error and further ameliorate the dynamic characteristics of dc–dc buck converters. The design of the DDPG is realized in two parts: (i) an actor-network which generates the policy commands, while (ii) a critic-network evaluates the quality of the policy command generated by the actor. The suggested strategy establishes the DDPG-based control to handle for what the iPI-based SM observer is unable to compensate. In this application, the weight coefficients of the actor and critic networks are trained based on the reward feedback of the voltage error, by using the gradient descent scheme. Finally, to investigate the merits and implementation feasibility of the suggested method, some experimental results on a laboratory prototype of the dc–dc buck converter, which feeds a time-varying CPL, are presented. [ABSTRACT FROM AUTHOR]

In order to enhance the dynamic performance of surface-mounted permanent magnet synchronous machines (PMSMs), this letter proposes an improved finite control set (FCS) model predictive direct speed control (MPDSC) strategy that only contains one speed control loop. In comparison with the traditional two-step prediction method, the new controller is achieved by estimating the current at first and then the speed with only one prediction horizon. The practical problem that the optimal switching state cannot be selected by the common implementation procedures of the FCS model predictive control algorithms can be solved by applying the proposed strategy, which conforms more to the real situations. Moreover, in order to solve the other critical problem that the load torque (LT) in the predicting plant is unknown, a novel sliding mode LT observer is developed. The simulation and experimental results prove that the proposed algorithms are effective. [ABSTRACT FROM AUTHOR]