Applied Mechanics and Materials Vol. 785

Abstract: Photovoltaic power conditioning system (PVPCS) requires a high efficiency dc-dc converterstage capable of wide input voltage regulation and have the ease of maximum power point implementation for both stand alone photovoltaic system and grid-connected system. Galvanic isolation at the dc-dc stage can replace the isolation needed in the inverter stage and thus reduce the sizeof isolation transformer and increases overall system efficiency. This paper presents detailed analysis,design and implementation of a LLC resonant converter for photovoltaic battery charging application.The LLC resonant converter operate with zero voltage switching (ZVS) turn on and low current turnoff thus reducing switching losses. The experimental results are given to validate the operation andperformance of the converter.

Abstract: An identification system of multiple-input single-output (MISO) model is developed in controlling dsPIC microcontroller of positive output buck-boost (POBB) converters for module mismatch condition of photovoltaic (PV) system. In particular, the possibility of the scheme is to resolve the mismatch losses from the PV module either during shading or mismatch module occurrences. The MPPT algorithm is simplified by identification approach of indirect incorporated with a simple incremental direct method to form a combined direct and indirect (CoDId) algorithms. Irregular consumption of solar irradiation on a PV module shall step-up or step down the voltage regarding to the desired DC output voltage of POBB converter. This optimized algorithm will ensure that the PV module to kept at maximum power point (MPP), preventing power loss during module mismatch incident in PV module especially during partial shading condition. The simulation and laboratory results for PV module of polycrystalline Mitsubishi PV-AE125MF5N indicate that the proposed model and development of PV system architecture performs well, while the efficiency up to 97.7% at critical of low solar irradiance level. The controlling signal is based on low-cost embedded microcontroller of dsPIC30F Digital Signal Control (DSC).

Abstract: Cascaded H-Bridge (CHB) multilevel inverter (MLI) is among the most preferred topology in solar PV systems. While traditional asymmetric CHB MLI is easy to achieve higher number of output voltage levels compared to traditional symmetric CHB MLI, charge balancing between the voltage sources remains a challenge for asymmetric CHB MLI. This drawback results in unsteady DC voltage levels due to unbalanced power drawn from each voltage sources. Besides that, in battery powered applications, unbalanced power drawn results in unequal discharged among the batteries. In this paper, an asymmetric half H-bridge (HHB) MLI topology is presented which is easy to modularize as for symmetric CHB MLI while maintaining the ease in charge balancing control. The performance of this proposed asymmetric HHB MLI with charge balance control has been evaluated using PSIM software.

Abstract: The study of the effects of an internally and externally caused disturbances for the advanced hybrid fuzzy-fuzzy controller (HFFC) scheme in order to gain control over the speed of an induction motor’s (IM) variable speed drive (VSD) is the main objective of this research paper The HFFC works on the principle of gaining control over the rotor speed during steady-state stage using fuzzy stator current magnitude controller whereas, during an accelerate-decelerate stage by utilising a fuzzy frequency controller, to overcome the disadvantage of field oriented control (FOC) method. The design of a scalar controller involves two aspects of FOC i.e current and frequency. Hence, the performance of a controller has been observed with a series of tests which yielded a controller which is more effective, consistent and insensitive to the parameter variation for the motor and system strength to noise and load disturbances.

Abstract: This paper presents a selective harmonic elimination (SHE) modulation technique for cascaded H-bridge (CHB) multilevel inverter. The main advantage of the proposed SHE concept is its simple implementation to eliminate the specific order harmonics. The procedures used to achieve the appropriate switching angles are presented. The switching angles are offline computed using the Newton-Raphson method. The SHE scheme of the adopted inverter uses the relationship between the angles and a sinusoidal reference waveform through some combinational logic gates. Theoretical results are verified by the experimental work of a single-phase 7-level CHB inverter employing an Altera DE2 field-programmable gate array (FPGA). Results show the inverter producing an optimum stepped output voltage when selected low-order harmonics are eliminated and the voltage total harmonic distortion (THD) is improved.

Abstract: This paper presents a mathematical model of photovoltaic with buck converter to analyze the voltage and current as a result of radiation and temperature changes as the input signal. Photovoltaic simulator models created using the C programming integrated with Matlab Simulink. The IP controller is used to control the current of a buck converter with the reference current from the dynamic model of photovoltaic. The control signal from the IP controller is used for generating a PWM signal, which is used to drive the IGBT gate of the buck converter. Input of irradiance and temperature are given to the photovoltaic simulator. Moreover, the current and voltage of the buck converter are used as a feedback to the photovoltaic simulator. This experiment is run through the system in real time and the simulation results show that changing in radiation has more significant effect on the output voltage of a solar power system compared to changing in temperature.

Abstract: This paper presents the modeling of a full-wave rectifier circuit based on piezoelectric vibration transducer for energy-harvester system. Piezoelectric vibration crystals are a viable means of harvesting energy for low-power embedded systems e.g. wireless sensor network. Distinct power handling circuits are assessed with the presence of piezoelectric vibration based energy harvesting transducer. Inside the interface circuit, the voltage should be started up when the AC input voltage is very low to supply a regulated DC voltage up to 2V. An active technique is chosen to design an ultra-low power circuit from a piezoelectric vibration transducer. MOSFET bride ac–dc rectifier, energy storage device e.g. capacitor and boost converter with regulator are the common components of the energy harvesting circuits. An integrated promoter ac-dc rectifier circuit and boost converter that accept a maximum input voltage of 0.3V and provide a regulated output voltage of 2V serve as the supply. The MOSFET and thyristor are considered to develop the proposed circuit replacing conventional ac-dc rectifier due to low input voltage at which diode does not work.

Abstract: This paper presents the design study of Zero-Voltage-Switching (ZVS) for resonant dc/dc boost converter with M-type switch. Throughout the study, all parameters had been calculated in order to determine the parameter values of the converter and mathematical analyses had been performed. The simulation was performed using PSpice software. Through this process, all the parameters values can be determined for further design.

Abstract: Renewable energy sources like solar PV produces DC voltage which is converted to AC before connecting to domestic grid network. The conversion process from DC to AC and back to DC at load end introduce additional losses in the system. With increasing availability of modern DC loads and growing use of renewable energy, the use of DC network for domestic load supply is on increase in order to reduce energy conversion losses. Presented in this paper is a fast transient digital controller for DC-DC boost converter with energy source from solar PV for domestic DC loads like lightings. The boost converter was model as both steady and dynamic state. Digital controllers were designed using both digital redesign approach and direct digital redesign approach. The system demonstrated fast transient response that is essential for tightly regulated output voltage from constantly varying renewable energy generations.

Abstract: Space vector pulse width modulation (SVPWM) technique is an advanced computation-intensive PWM method. It is the best among all PWM techniques for three-phase induction motor (TIM) drive applications because of its superior performance characteristics. In this paper, the use of artificial neural network (ANN) based SVPWM technique avoids the computational complex used in conventional SVM implementation. An ANN scheme structure is suggested to identify and approximate the conventional SVPWM for decrease the computational problem. Moreover, proportional-integral (PI) controller tuning is achieved using a particle swarm optimization (PSO) algorithm to improve the TIM speed controller’s response performance. By designing an appropriate PSO algorithm, kp and ki of the PI speed controller parameters are tuned for TIM to attain the best parameter values.