Manel Hammami

A Comprehensive Analysis and Hardware Implementation of Control Strategies for High Output Voltage DC-DC Boost Power Converter

Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV) dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned deficiencies. The control strategy is based on classical proportional-integral (P-I) and fuzzy logic closed-loop controller to get high and stable output voltage. Complete hardware prototype of EHV is implemented and experimental tasks are carried out with digital signal processor (DSP) TMS320F2812. The control algorithms P-I, fuzzy logic and the pulse-width modulation (PWM) signals for N-channel MOSFET device are performed by the DSP. The experimental results provided show good conformity with developed hypothetical predictions. Additionally, the presented study confirms that the fuzzy logic controller provides better performance than classical P-I controller under different perturbation conditions.

Improvement of the integration of a grid-connected wind-photovoltaic hybrid system

This paper presents control strategies for the integration of a grid-connected wind-photovoltaic hybrid system via adaptation converters connected to a common DC bus. For both wind and solar system, adequate control algorithms have been implemented for the maximum power extraction. The grid side converter has been connected to the point of common coupling (PPC) through an RL filter. The control of the grid side converter (GSC) was made in order to control the power quality and quantity of the feed power to the grid. At the DC bus, a PI-regulation control was adopted to overcome the ripples caused by the power flow. Performances of the adopted control laws have been evaluated by MATLAB/Simulink simulations.

Evaluation of DC voltage ripple in single-phase H-bridge PWM inverters

In this paper the complete analysis of the dc-link voltage ripple is given for single-phase H-bridge PWM inverters. The dc voltage ripple amplitude is analytically determined as a function of the modulation index and the load phase angle, considering both the switching frequency component and the double fundamental frequency component (i.e. 100 Hz). Peak-to-peak distribution, maximum amplitude, and rms values of the voltage switching ripple over the fundamental period are analytically determined and numerically verified by numerical simulations carried out by Matlab/Simulink. Simple and effective guidelines to design the dc-link capacitor are given on the basis of the dc-voltage ripple requirements.

An improved MPPT algorithm based on hybrid RCC scheme for single-phase PV systems

Single-stage H-bridge grid-connected inverters are considered as a simple, compact, and economic topology compared with double-stage converters. A maximum power point tracking (MPPT) control is necessary in photovoltaic (PV) generation system to extract maximum power from the PV arrays. Many MPPT techniques have been proposed and discussed in the literature. Among them, the ripple correlation control (RCC) algorithm is fast and effective, particularly suitable for single-phase configurations since it uses as perturbation the embedded oscillation of dc current and dc voltage at twice of grid frequency (e.g., 100 Hz). The main drawback of this method is the unstable behavior during sudden variation of sun irradiance, where the conventional RCC gives wrong estimation of the power derivative (dP/dV), causing wide dc voltage and dc current overshoots. To overcome this problem, a hybrid RCC-constant voltage regulator algorithm combined to a high-peformance dq grid current controller is proposed to improve the transient performance. The whole grid-connected photovoltaic generation scheme has been implemented numerically by MATLAB/Simulink, verifying steady-state and dynamic performances under different sun irradiance transients. The comparison with the corresponding behavior of a standard RCC algorithm emphasized the effectiveness of the proposed hybrid RCC controller.

Evaluation of DC voltage ripple in three-phase PWM voltage source inverters

Determination of dc-link voltage switching ripple in three-phase PWM voltage source inverters (VSI) is important for the selection and design of the dc-link capacitor. In this paper the complete analysis of the dc-link voltage ripple is given for three-phase PWM VSIs, in case of dc source impedance and balanced load. The dc voltage ripple amplitude is analytically determined as a function of amplitude and phase angle of output current, and modulation index. In particular, peak-to-peak distribution and maximum amplitude over the fundamental period of the dc voltage switching ripple are obtained. Guidelines for designing the dc-link capacitor are given on the basis of the dc-voltage ripple requirements. Simulations results carried out by Matlab/Simulink are provided to verify the analytical developments.

RCC-MPPT algorithms for single-phase PV systems in case of multiple dc harmonics

In this paper the implementation of maximum power point tracking (MPPT) schemes by the ripple correlation control (RCC) algorithm is discussed in case of multiple ripple harmonics. As an example, a single-phase single-stage grid-connected photovoltaic (PV) system based on H-bridge inverter and level doubling network (LDN) is considered, leading to a multilevel inverter having the double of output voltage levels compared to the basic H-bridge inverter topology. The LDN is basically a half-bridge fed by a floating capacitor, with voltage self-balancing capability. In this case, additional voltage and current harmonics are introduced in the dc-bus of the H-bridge, leading to multiple PV voltage and current low-order harmonics comparing to the double fundamental frequency component in case of basic H-bridge configuration. Voltage and current harmonic components are used in RCC schemes to estimate dP/dV and to drive the PV operating point to the MPP. Different possible dP/dV estimations have been proposed in case of multiple harmonics, and a specific case with LDN has been considered. The steady-state and transient performances of the proposed RCC-MPPT schemes have been numerically tested and compared by MATLAB/Simulink.