It is well known that the super-twisting algorithm is robust to matched perturbation but is sensitive to measurement noise. Contrarily to this, the classical linear algorithm is less sensitive to measurement noise but less robust to perturbation. To combine both the good accuracy of super-twisting algorithm with respect to perturbation and the good performance of linear algorithm with respect to measurement noise, this paper proposes a new differentiator/observer with a varying exponent gain ${\alpha}$ whose variation depends on the magnitude of measurement noise (high frequency signal). When the magnitude of measurement noise increases (respectively decreases) ${\alpha}$ tends to 1 (respectively tends to 0.5) and the proposed differentiator/observer behaves as a linear algorithm (respectively as a super-twisting algorithm). Thus, by one parameter ${\alpha}$ the differentiator/observer can take care of high frequency noise and matched perturbations. A complete stability analysis of the proposed differentiator/observer is provided. To highlight the applicability of the proposed methodology, the dedicated differentiator/observer is respectively validated on electropneumatic actuator and electric machine testbenches. These experimental results are compared to those of linear and super-twisting algorithms.

A new technique to observe the electromagnetic torque of a permanent magnet synchronous machine (PMSM) based on flux linkage estimation considering unknown magnetic condition is presented in this paper. The magnetic behavior uncertainties including permanent magnet flux, linear self-inductances, linear coupling-effect inductances and magnetic saturations are taken into account as a set of new variables in the model of machine. Regarding the new model, an appropriate observer based on Kalman-like algorithm is proposed to observe those variables. Then, the variables are collected and used to estimate the stator flux linkages and consequently the machine torque. The observability as well as the stability of the observer for the proposed system is theoretically investigated. The simulation and experimental results are represented for different scenarios. They prove the effectiveness of the proposed method.

New control schemes based on sliding mode control and linear state feedback are proposed to ensure high tracking accuracy with relatively low energy consumption. A time-varying exponent parameter law (linked to homogeneity degree) is introduced to combine the advantages of sliding mode control (high accuracy and robustness) and the linear state feedback (low energy consumption). To show the effectiveness of the proposed approaches, experimental tests are conducted on an electropneumatic setup.

It is well known that the homogeneous differentiator strategies reduce the chattering in the implementation of sliding-mode algorithms and the recent implicit framework based projector provides very interesting properties when associated with homogeneous design. In this article, it is proposed to evaluate different strategies of homogeneous differentiators based on Euler explicit and promising Euler semi-implicit strategies, for which discrete implementations have been realized on a pneumatic actuator. Experimental results highlight the benefit of a Euler semi-implicit-based structure using a projector.

Electric Vehicle (EV) bidirectional charger technology is growing in importance. It defines the fact of returning the electricity stored in the batteries of EV to Grid (V2G), to Home (V2H), to Load (V2L), or in one word V2X mode. The EV onboard charger is divided into two parts: AC-DC and DC-DC converters. The isolated bidirectional DC-DC LLC resonant converter is used to improve the charger efficiency within both battery power and voltage ranges. It is controlled by varying the switching frequency based on a small signal modeling approach using the gain transfer function inversion method. The dimensions of the DC-DC LLC converter directly affect the charger cost. Moreover, they cause an important control frequency saturation zone, especially in V2X mode, where the switching frequency is out of the feasibility zone. The new challenge in this paper is to design an optimization strategy to minimize the LLC converter cost and improve the control frequency feasibility zone, for a wide variation of battery voltage and converter power, in the charging (G2V) and discharging (V2X) modes simultaneously. For our best knowledge, this optimization problem, in the case of a bidirectional (G2V and V2X) charger, is not yet considered in the literature. An optimal design that considers the control stability equations in the optimization algorithm is elaborated. The obtained results show a significant converter cost decrease and important expansion of control frequency feasibility zones. A comparative study between initial and optimized values, in G2V and V2X modes, is generated according to the converter efficiency.

Control of a perturbed electric power system comprised of a hydrogen fuel cell (HFC), boost and boost/buck DC–DC power converters, and the ultra-capacitor (UC) is considered within an electric vehicle application. A relative degree approach was applied to control the servomotor speed, which is the main controllable load of the electric car. This control is achieved in the presence of the torque disturbances via directly controlling the armature voltage. The direct voltage control was accomplished by controlling the HFC voltage and the UC current in the presence of the model uncertainties. Controlling the HFC and UC current based on the power balance approach eliminated the non-minimum phase property of the DC–DC boost converter. Conventional first order sliding mode controllers (1-SMC) were employed to control the output voltage of the DC–DC boost power converter and the load current of the UC. The current in HFC and the servomotor speed were controlled by the adaptive-gain second order SMC (2-ASMC). The efficiency and robustness of the HFC/UC-based electric power systems controlled by 1-SMC and 2-ASMC were confirmed on a case study of electric car speed control via computer simulations.