Currently electric vehicle (EV) charging stations are equipped with chargers having fixed charging rates where the users do not have control over their charging schedule, except to decide whether they require a full recharge or partial recharge. In addition, no matter what kind of charging technique is adopted, EV charging takes much time compared to refueling conventional vehicles. This lengthy time at a charging station is the reason why people are hesitant to switch to EVs from internal combustion engine vehicles. The long waiting time may lead to congestion at the charging stations. This has motivated us to develop an efficient multi-level charging system (MlCS) that allows EV customers to specify their charging needs and provide them with charging at the best charging rate possible. The proposed MlCS put forward here features multiple charging levels on a single charger and each level corresponds to a distinct charging rate. Taking the interest of customers into account, the selection of charging rate for the customer is based on his priority for battery lifetime and recharging time. Further, the MlCS is integrated into the station planning problem to analyze the effect of MlCS on station capacity estimation and their impact on the power grid. Finally, the numerical results illustrate that MlCS is better for improving the customer quality of service. The contribution of the proposed model allows decision-makers and operators to develop charging stations with multi-level chargers and provide a better service for customers with different charging options.

This paper proposes the use of backstepping technique to address the stabilization problem of a dc-dc boost converter characterized by non-minimum phase property. The backstepping technique is used in conjunction with a disturbance observer to counteract the effect of model uncertainties and unmeasured disturbance. Therefore, not only does the developed controller achieve the task of stabilization, but it can also guarantee zero steady-state error in the presence of model uncertainties and unknown load. The asymptotic regulation of the composite controller follows from the integral action property of the disturbance observer. What is more interesting is that the composite controller can also compensate for the effect of control saturation during transients. This means that the proposed controller does not require an anti-windup scheme to maintain stable and graceful response during control saturation. Another feature of the proposed controller is its ability to achieve good tracking performances in response to a smooth voltage trajectory. Simulation and experimental tests have been conducted to investigate the performances of the proposed controller considering different operating conditions and different load types, including constant power load (CPL). The obtained results revealed that the proposed controller is able to achieve stable, accurate, and good response regardless of the load type.

This paper presents a disturbance observer-based control (DOBC) for stand-alone inverters to produce sinusoidal voltages. The controller is specifically designed to regulate the output voltage of the inverter to follow a desired sinusoidal voltage reference. The disturbance observer is employed to ensure accurate tracking of the voltage reference by compensating for model uncertainties and unknown inputs. The combination of a linearizing feedback control (LFC) with a disturbance observer (DO) makes it possible to perform dual functions by providing improved disturbance rejection during transients and attaining zero steady-state error thanks to the integral action property of the disturbance observer. The key feature of the proposed controller is that it is designed in the dq reference frame, but it is implemented in stationary αβ coordinates. The performance of the above controller during load variations is verified via simulation tests. The test results have demonstrated excellent disturbance attenuation to achieve good transient response during balanced and unbalanced load variations.

In this paper, a robust dynamic compensator together with anti-windup scheme for a grid tied inverter with L filter is proposed to provide satisfactory tracking performance of the reference signal under control input saturation. The control implementation is performed in the αβ reference frame to make the systems output matches a sinusoidal reference signal with zero tracking error. The sinusoidal current references are calculated using the active power command, reactive power command, and sequence voltages to deal with both balanced and unbalanced grid voltages. The dynamic compensator has the property of a resonant action in that it ensures accurate tracking of sinusoidal references in the presence of sinusoidal disturbances with known frequency. With the resonant behavior of the feedback controller, considerable overshoot and settling time may occur in the transient response, particularly during control saturation. To compensate for the effect of control input saturation, the dynamic compensator was modified to include an anti-windup compensator. The role of the anti-windup scheme is to improve the quality of the transient behavior during control input saturation. Simulation tests were used to verify the suggested controller performance. The proposed composite controller demonstrated excellent tracking performance with a graceful degradation during control saturation under both balanced and unbalanced grid voltages.

Recently, the control problem of a quadrotor unmanned aerial vehicle (UAV) has been undergoing massive research. In this paper, a nonlinear disturbance observer-based (NDO) controller is proposed for attitude and altitude control of a quadrotor, in order to estimate and compensate disturbances that are imposed naturally on the quadrotor due to aerodynamics and parameter uncertainties. It is demonstrated herein that the proposed observer can estimate external disturbances asymptotically. Subsequently, it is employed with an input-output feedback linearization (FBL) controller - rendered as a baseline controller - to achieve a composite controller capable of rejecting external disturbances rigorously. The resulting controller is compared with a FBL controller that is equipped with an integral component. Simulation results demonstrate a superior performance using the former controller for disturbance rejection.

A robust nonlinear predictive controller with a disturbance observer for a permanent magnet synchronous motor (PMSM) is presented. As the disturbance relative degree is less than that of the input, it is quite challenging to adopt the existing disturbance observer-based predictive control techniques. In the proposed controller, robustness of the closed loop system with respect to mismatched parameters and unknown load torque is significantly improved. Stability of the closed-loop system is proved, and the controller is easy to implement. Validity of the proposed controller was experimentally tested on a dSPACE DS1104 board driving a 0.25 kW PMSM drive. Excellent results were obtained with respect to the speed trajectory tracking performance and robustness.