Analysis and implementation of a step–up power converter with input current ripple cancelation

This paper analyzes a coupled inductor based $LL$ – $LC$ network as a building block to achieve input or output current ripple cancellation in power converters. The proposed current ripple cancellation technique works on the principle of inductance matching. It also provides reduced current stress on the switching devices of the converter compared with the other current ripple cancellation networks discussed in the literature. The current ripple cancellation technique is verified in achieving input and output current ripple minimization in different converters. The effect of inductance mismatch, inductor and capacitor tolerances, and circuit parasitic is also studied. Some of the published research works are demonstrated to be a special case of the proposed idea. The effectiveness of the proposed method is validated by demonstrating the zero-ripple input current using a 31 V dc to 60 V dc, 240 W boost converter prototype and a 31 V dc to 115 V (rms) ac, 320 W current-fed-switched inverter prototype, and the zero-ripple output current using a 62 V to 42 V dc, 450 W buck converter prototype.

In renewable energy power conditioning system (PCS), like photovoltaic (PV) and fuel cell sources, the low input current ripple represents a very important issue to improve the source efficiency. This paper presents an analysis of the power losses and efficiency of two high boosting converters for PV and fuel cell applications, designed by the authors. The two converters are characterized by a single switching device and, the first topology, by a reduced input current ripple and, the second one, by a zero input ripple condition. In particular, the free ripple condition of the second topology is obtained by coupling the two inductors that are uncoupled in the first topology. A detailed mathematical analysis of the power losses and efficiency is presented together with an evaluation of the effects on the efficiency caused by coupling the inductors. The proposed concepts are demonstrated by simulation.

This paper discusses applying various switching strategies such as conventional complementary and proportional methods on a specific converter. This converter was recently presented and it can provide high voltage gain and has current ripple cancelation ability at a preselected duty-cycle. The input current ripple is zero when the converter works at a special duty-cycle. But load disturbance leads to output voltage changes that maybe cause the duty-cycle to deviate from its preselected value. In this situation, the input current ripple cannot be completely canceled. The proposed proportional strategy is an optimized method for minimizing input current ripple at other operating duty-cycles and also it provides a voltage gain lower than conventional complementary strategy. Here, the converter's performance is analyzed under two switching strategies and the effect of various strategies has been investigated on converter parameters including output voltage and input current ripple. These considerations are verified by implementing a 100-W prototype of the proposed converter in laboratory.

This paper proposes an optimal methodology based on the Differential Evolution algorithm for obtaining the set of duty cycles of a recently proposed power electronics converter with input current ripple cancelation capability. The converter understudy was recently introduced to the state-of-the-art as the interleaved connection of two unequal converters to achieve low input current ripple. A latter contribution proposed a so-called proportional strategy. The strategy can be described as the equations to relate the duty cycles of the unequal power stages. This article proposes a third switching strategy that provides a lower input current ripple than the proportional strategy. This is made by considering duty cycles independently of each other instead of proportionally. The proposed method uses the Differential Evolution algorithm to determine the optimal switching pattern that allows high quality at the input current side, given the reactive components, the switching frequency, and power levels. The mathematical model of the converter is analyzed, and thus, the decision variables and the optimization problem are well set. The proposed methodology is validated through numerical experimentation, which shows that the proposed method achieves lower input current ripples than the proportional strategy.

When an existing photovoltaic (PV) system is upgraded to a residential PV/battery system, the single-phase PV inverter under both input conditions of battery and PV should be properly controlled to restrain the input current ripple and grid-current harmonics. To do this, equivalent circuits of PV array and Li-ion battery pack are first constructed and respectively analyzed. The analysis results show that the input current under the battery pack may contain serious ripple component due to the low internal impedance of the battery pack, which cannot suppress the ripple current caused by the inherent power coupling problem of the grid-connected single-phase inverter. Then, based on the small signal model of the boost dc-dc convertor, a novel active control method is proposed for mitigating the input current ripple, which adopts double-channel current feedbacks including an additional ripple current feedback channel and the normal one. To provide the feedback signal, a third-order general integrator is introduced to extract the current ripple. Besides, a proportional-resonant controller is used to restrain the grid-current harmonics. Finally, the control parameters are obtained using MATLAB toolbox, and the proposed control strategies are validated by the experimental results on a 5 kW prototype.

The main drawback of DC-source-based renewable energy sources (RESs), such as photovoltaic (PV) panels or fuel cells (FCs), is that the voltage generated by a panel or cell is less than the required voltage for connection to a DC–AC inverter for grid applications. In this paper, a single-switched DC–DC boost converter equipped with a quasi-impedance source inverter (QZSI) with a modified switching model is proposed to increase the output voltage of these RESs and convert it to a fixed AC grid voltage for loads. By changing the position of the inductor in a classic step-up converter and using a switched-inductor block, the input current ripple is significantly decreased, and the reliability and long-life of the input sources are increased, which is the main contribution of this work. The quality of the generated AC voltage and the low amount of total harmonic distortion (THD) in the projected topology are significant, and no overshoot and undershoot have been reported for both output voltages and currents under different operating conditions with variable loads. Theoretical analysis, simulation results, and comparison with similar topologies are examined and a prototype with a power of 200 to 400 watts is presented. Experimental results confirm the theoretical studies.

Global expansion of the EV market has led to widespread DC charging infrastructure. Consumers prefer DC charging over AC to reduce charging time per kilometer. However, grid-connected DC chargers can cause issues such as grid instability, power quality problems, demand imbalance, and conversion losses. This paper proposes an off-grid photovoltaic (PV) fed DC charger for EVs along with a battery energy storage system (BESS) to mitigate these challenges. The work aims to increase the use of clean energy for EV charging, to ensure uninterrupted EV charging with minimum power conversion stages, and to improve PV utilization. BESS serves as a backup power source that charges or discharges based on PV availability. Additionally, the system powers the non-critical adjustable loads of domestic/industrial sites with the available PV power when both EV and BESS are fully charged. The system can be reconfigured to operate in six distinct modes using two DC-DC converters and five relays. Among six modes, four modes operate in single-stage power conversion. A buck converter is used to extract power from PV. A bidirectional buck-boost converter is used to charge and discharge the BESS. The proposed system is validated through hardware prototype for both steady-state and transient conditions.

Application of PV Panels in Large Multi-Story Buildings Feasibility Study Sara Kayal The awareness of global warming along with an ever increasing demand for a new source of energy has brought a strong interest in harnessing natural resources such as solar energy. This thesis evaluates the viability of applying photovoltaic (PV) panels in high-rise commercial buildings of around 20 stories. Specifically, the thesis is intended to provide a pre-planning tool during the early design stage for architects and designers who are considering the deployment of PV panels in new multi-story construction. The first three chapters cover a comprehensive literature review and describe several case studies of the application of PV panels in multi-story buildings. The first chapter serves as an introduction to the objectives and rationale of PV panel research. Chapter 2 explains the physics and characteristics of PV panel technology that is applicable to multi-story buildings. Various PV panel types are explored in this chapter and it is suggested that window-based PV panels are the most suitable type for multi-story buildings in which the available roof area is small in area and limited in flexibility due to competition with other uses. Chapter 3 investigates factors that influence the efficiency of PV panels. These factors reduce the efficiency of PV panels to about 10-15%. In Chapter 4 a study model is presented to validate the results of the previous chapters and to determine the feasibility of PV panel systems with the aid of computer model analysis and simulation. The study model includes a base case of a 20-story building that is surrounded by four adjacent buildings, one adjacent to each orientation. Five configurations of the base model with different arrangements of PV panels were analyzed. First, electrical energy of the base case was calculated without applying any PV panels. The second and third configurations include PV panels on all of the available façade areas on a typical summer and winter day, respectively. The fourth and fifth configurations feature PV panels on only the top 10 floors. The simulation results show that although some savings accrue over a 25-year life-cycle period, these savings pale in comparison with the initial capital cost associated with the purchase and installation of the PV panels. It was also found that although crystalline silicon panels have a higher initial cost, their superior efficiency and performance present them as better candidates for PV panel applications. In addition,

In this paper, a novel nonisolated interleaved high step-up DC-DC converter is proposed based on the coupled inductor and voltage multiplier cell (VMC) methods. Due to the interleaved structure, its input current ripple is low. The low input current ripple and also high power efficiency make the proposed converter suitable for renewable energy applications like photovoltaic (PV) and fuel cell (FC) power generation systems. The windings of the coupled inductors are combined with VMCs to further increase the output voltage with a low power switch’s duty cycle. This combination also leads to obtaining a flexible voltage gain that can be adjusted by coupled inductors’ turns ratio and power switches’ duty cycle. The voltage peaks over semiconductors are much lower than the output voltage. Therefore, low-rated semiconductors can be used for the implementation of the proposed converter, which can reduce the cost and volume. Generally, high voltage gain, low voltage, current stress of power switches, low input current ripple, high efficiency, common ground between the input and output ports, and a low number of elements are the main benefits of the suggested structure. The operation principle, steady-state analysis, and comparison with other converters are presented to show the advantages of the suggested converter. Also, a prototype is built, and the experimental results are presented to prove the theoretical analysis. This prototype is implemented with 200 W rated power, 25 V∼400 V voltage conversion, and 50 kHz switching frequency. Additionally, the efficiency is measured at 95.3% at the rated power.

In a high power converter design for fuel cell applications, the usefulness of interleaving power converter module has become apparent. The benefits of interleaving include: reduced rms current in the do bus capacitors; ripple current cancellation in the input and output waveforms; reduction of size and volume of input inductors, enabling the simplicity to obtain Ferrite-core and Litz wire size; improved transient response as a result of reduced input inductance and higher input and output ripple frequency; separation of heat generating components; and power converter segmentations, enabling the superior reliability. So, this paper presents a fuel cell current control loop of the proposed 4-phase interleaved boost converter for high power fuel cell applications. Experimental results of the proposed FC converter (1.2-kW) at 25-kHz PWM switching frequency connecting with a Nexatrade PEM fuel cell (1.2-kW, 46-A,) collaborate the excellent performances: static and transient states of the design system.

This paper considers input current-ripple reduction on Pulse-link DC-AC converter for fuel cells applications operated by zero-current-slope mode. For reducing the input current-ripple, series LC circuit has been connected in parallel at the Pulse-link DC-AC converter. The input current-ripple characteristics have two main domains with combination of series LC parameters. The current-ripple level depends on inductance values. Input current-ripple is reduced when the inductor current flown at series LC circuit has zero-slopes in one switching period. At that time, small parameters values can be achieved.

Photovoltaic (PV) systems are emerging as a prevalent renewable energy source for electricity generation. PV systems utilize photovoltaic cells for converting solar energy to electrical energy. However, the intermittent nature of solar energy limits the applications of PV systems in numerous fields of power engineering. To overcome this limitation, this paper presents a hardware prototype of the grid connected PV system with energy management system using batteries. The battery based energy management system provides a stable and reliable power output from PV system irrespective of the variations in solar energy. The energy management deploys bi-directional DC-DC converter for controlled charging and discharging of batteries. Single phase inverter has been employed for converting DC power output from PV cells to AC power. The grid synchronization control of the inverter has been achieved through TI-MSP430 microcontroller launch pad kit. Various modes of operation of the grid connected PV system are tested using the developed hardware prototype.

A general analytical solution is derived for an electric potential produced by a direct current point source located at any position in a multilayered spher ical volume conductor. Starting from Poisson's equation, the electric potential whose coefficients are rapidly got in the form of matrix expressions is obtained according to the boundary conditions. Simulation for a four-layered spherical volume conductor denoting the scalp, skull, cerebrospinal fluid and brain tissue proves that electric potential in this paper converges more rapidly in the whol e region than that expressed only in spherical harmonics expansion form, and ite rative times decrease. Electric potential contour and current streamline figur es show that it is important to consider the effect of the low conductivity of s kull on electric potential and current flow. The distribution of electric potent ial on the surface of sphere is discussed, which will be useful in electroenceph alography inverse problems, and also in analyzing and interpreting the electric potential measurement.

The electrical energy generated by photovoltaic (PV) modules depends on solar radiation, environmental and climatic factors as well as inherited system and component performances. However, the other external factor such as dust also has significant effects on the performance. This chapter discusses the deposition of dust particles on the PV module surfaces and their effects on system performance. The chapter begins by discussing the fundamentals of a PV module and dust particles originality, transportation and the factors that govern their deposition. Results show that the accumulation of dust particles on PV module surfaces is influenced by dust particles properties (size, shape and chemical properties), environmental conditions (wind speed, location and distance to the dust source, dust concentration and weather condition) and PV module characteristics (tilt angle, orientation and properties of surface material). On the other hand, the presence of dust particles on PV module surfaces reduces significantly the transmitted incident light to the solar cells which in turn decreases the value of the short-circuit current (ISC), maximum power output (Pmax), fill factor (FF), conversion efficiency (η) and energy yield. The rate of decrease of each parameter increases as the dust particles deposition density increases. In addition, the reduction in ISC, Pmax, FF, η and energy yield depends on the physical properties of dust particles such as mean diameter, size distribution and chemical composition. The effect of dust on the performance of PV modules can be eliminated by cleaning the dust particles using different methods. These methods are classified as natural, manual and automatic.KeywordsDust particleDust particle depositionEffect of dust on PV module parameters

In this paper, a high efficiency interleaved flyback (IFB) converter is proposed for photovoltaic (PV) electric power generation. An incremental conductance (INC) based maximum power point tracking (MPPT) algorithm is implemented for the proposed PV system to maximize the output power extracted from the PV array. Among the isolated converter topologies, flyback converter is selected for its simple configuration and low cost. It is also the most popular isolated converter used in low power, electronic applications. Interleaving technique is applied for the flyback converters in order to reduce the input current and output voltage ripples, and to increase the efficiency. A 100 W prototype is developed and tested. The simulation and experimental results obtained for different irradiations validate the effectiveness of proposed converter for the PV applications.