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This paper proposes a new instantaneous model of a single-phase shunt hybrid power filter. The proposed model is derived using the switching-function approach. The existence of such model allows, first, a real-time simulation and analysis of the performance of the filter for several operating conditions and, secondly, a systematic design of the suitable controllers that ensure a high power quality at the mains and a voltage regulation at the DC-side of the filter. In order to illustrate the utility of the proposed model, a design of simple linear current and voltage regulators, based on an averaged version of the model, is also presented. The control system is implemented numerically using the Simulink tool of Matlab. Simulations are carried out and the obtained results are proven to be satisfactory. Finally, experimental results obtained from a laboratory prototype of the filter are included in order to validate the theoretical considerations used both in the development of the mathematical model of the filter and the design of the appropriate control system.

In this paper, practical considerations concerning the design and implementation of a single ended primary inductance converter (SEPIC) pre-regulator are addressed. Compared to conventional buck or boost converters, this topology allows a low current ripple at the input for a relatively low level of the DC-bus voltage. Consequently, the high frequency filter needed at the AC- side of a buck converter is avoided, and the high voltage stresses applied on the switches are significantly reduced with respect to the boost converter. The converter is integrated as a power factor correction circuit at the DC-end of a single-phase diode bridge. A pulse-width-modulated (PWM) control scheme is developed and applied to 1 kW laboratory prototype of the converter in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The experimental setup is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), voltage regulation, robustness and dynamic time response to a set point offset.

The proposed paper aims to analyse the control saturation phenomenon and its influence on the steady state converter performance. This analysis is performed for two main targets: 1) Rating AC line inductors, while fulfilling the compromise between a minimal value required to limit main currents ripple at used switching frequency, and a maximal value that maintains the current modulation capability and consequently limits the control saturation phenomenon, 2) Tuning the digital controllers parameters, in order to reduce control saturation on the one hand, and ensure low Total Harmonic Distortion (THD), unity Power Factor (PF) and regulated split DC bus voltages on the other hand. The obtained results clearly show a fundamental dependency between the saturation angle, voltage unbalance controller parameters, and both line inductors size and required output load power.

This paper introduces a new approach based on the use of nonlinear switching functions in sliding mode control. These nonlinear functions are used to eliminate transient constraints on the control input and therefore to increase the speed performance of the controller without having a negative effect on the control input. This approach is brought up in a general perspective to nth order single input systems. In order to validate the superiority of this novel approach over the conventional sliding mode control, simulation results of a current-controlled magnetic levitation system are compared for both the conventional and the new techniques.

This paper presents a detailed study of a Series Hybrid Power Filter (SHPF). The system consists of a small-rated series active power filter and a series tuned passive filter. This combination is suitable for compensating voltage type harmonics-producing load. The hybrid control approach adopted is based on detecting both source current and load voltage harmonics. This technique enhances the compensation characteristics of the proposed system. A low-frequency mathematical model of the series hybrid filter is established. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q) synchronous frame. Then, suitable multiple-loops PI controllers are designed on the basis of the system's transfer functions and the use of the linear feedback control. Simulation results are shown in an attempt to verify the mathematical model of the filter and the effectiveness of the hybrid control approach for voltage harmonics compensation.