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This paper presents the experimental implementation of a buck converter with quasi-sliding mode control combined with a loss estimator function. An online loss estimator is developed to estimate, in real time, the parasitic resistances of the converter and variations of the resistance in the load. The estimated loss resistance and the resistance of the load are embedded, in real time, into the model equations of the controller using Zero Average Dynamics and Fixed Point Induction Control techniques (ZAD-FPIC) to improve the control robustness to resistive parameter variations. Details of the experimental setup are presented to show developed electrical and electronic circuits, and experimental techniques are described to ensure the successful digital implementation of closed-loop control of the buck power converter. The proper shielding of electrical wiring in power electronics allows improvement to the quality of the measures by removing noise induced by electromagnetic interference. A trigger signal is used to implement the Pulse-Width Modulation (PWM) with centered pulse and to synchronize the sampling of analogical signals from the buck converter. Such synchronization allows the use of a lower sampling frequency and ensures the measurements at the right instant in time. Experimental results are in good agreement with numerical simulations, showing the effectiveness of the control approach.

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Electro-Mechanical Valve Actuators (EMVA) are a promising solution to actuate engine valves for future camless engines. Their use can increase engine power, reduce fuel consumption and pollutant emissions, and improve significantly engine efficiency. This paper is concerned with the soft landing control of a double magnet EMVA system. In particular, a force control algorithm based on a combined feedforward and feedback sliding mode control actions is presented. The aim of the control is to stabilize the system while tracking a model-based reference trajectory. It is shown by numerical simulations that the proposed control approach guarantees soft landing operation even in the presence of external force perturbations and friction force variation

Several technological applications require well-designed control systems to induce a desired speed in direct current (DC) motors. Some controllers present saturation in the duty cycle, which generates variable switching frequency and subharmonics. The zero average dynamics and fixed point induction control (ZAD-FPIC) techniques have been shown to reduce these problems; however, little research has been done for DC motors, considering fixed switching frequency, quantization effects, and delays. Therefore, this paper presents the speed control of a DC motor by using a buck converter controlled with the ZAD-FPIC techniques. A fourth-order, non-linear mathematical model is used to describe the system dynamics, which combines electrical and electromechanical physical models. The dynamic response and non-linear system dynamics are studied for different scenarios where the control parameters are changed. Results show that the speed of the motor is successfully controlled when using ZAD-FPIC, with a non-saturated duty cycle presenting fixed switching frequency. Simulation and experimental tests show that the controlled system presents a good performance for different quantization levels, which makes it robust to the resolution for the measurement and type of sensor.

Electro-mechanical valve actuators (EMVA) are a solution for implementing variable valve actuation in internal combustion engines. Their use can increase engine power, reduce fuel consumption and pollutant emissions, while significantly improving engine efficiency. The control of this actuator is a complex task since non-smooth nonlinearities, parameter variations and external forces strongly affect plant dynamics. In addition, the impact of the valve at its end-strokes translates into mechanical wear and unacceptable noise, and in the worst case the electromagnet may also fail to catch the valve, causing system failure. The design of effective control strategies to ensure valve capture with low impact velocities is therefore essential for the correct functioning of such a mechatronic device. In this paper, the control problem of reducing the impact velocity at "landing" known in the literature as soft landing control, is tackled via novel cycle-by-cycle adaptive force compensation control algorithms. Two schemes are presented: a discrete adaptive proportional integral controller to regulate landing velocity to a preassigned set-point, and a gradient descent method based controller to automatically achieve the minimum admissible impact velocity. The effectiveness of both methods in limiting landing velocities is shown numerically using a high predictive simulator of the EMVA system, when considering unknown varying environmental conditions, such as internal friction and external gas pressure forces.

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Electro-mechanical valve actuators (EMVA) formed by two opposed electromagnets and two balanced springs are appealing solutions to implement advanced combustion concepts for camless engines. A crucial control problem for this valve actuator regards the first valve lift manoeuvre (termed 'first catching') to be rapidly performed after each insertion of the engine ignition key, when the EMVA rests at middle position where electromagnets offer low control authority. The control problem is challenging due to system nonlinear behavior. Mathematically, the EMVA system can be assumed to be a spring-mass impacting system affected by a non-smooth friction force and a dynamic saturated magnetic force. In this work an effective valve position-based first catching control strategy is proposed to control the strongly nonlinear system. Bifurcation analysis and parameter space simulations are used to study the closed-loop system behavior and to tune the controller gains as well. The effectiveness of the control approach is validated through numerical simulations of a highly predictive dynamic model of the valve actuator developed by authors in a previous work.