Comparison of the input filter effect to PV panel by SEPIC MPPT converter

Analysis and minimization of input current and voltage ripples of five-phase PWM inverters are presented in this paper. The analytical expressions for the RMS value of input current and voltage ripples as a function of the PWM reference signal are derived. Different to three-phase PWM inverters, it is shown that pure sinusoidal is the optimum reference signal that produces minimum input voltage ripple. Input current ripple does not depend on the employed reference signal so the ripple canpsilat be minimized by changing reference signal. Simulation and experimental results verify the analysis.

In addition to their conventional use in electric motor drives, DC-DC converters have a variety of other uses, such as energy storage, energy conversion, cyber security systems, uninterruptible power supplies, and renewable energy systems. An innovative DC-DC converter is suggested in this article. Designing a new, high-gain DC-DC converter scheme known as a double-switch SEPIC-buck converter (DSSB) is possible after making some adjustments to the SEPIC converter that is currently known in accordance with accepted techniques. The output voltage magnitude of the proposed converter is either larger than or less than the input voltage magnitude and is the same sign as the input voltage. According to the theoretical and analytical study that has been supported by the real-world application, high voltage gain, low switching stress, and low inductor current ripple are the main characteristics of the proposed DSSB converter. The related small-signal model was also used to build the closed-loop system. The frequency response and output voltage behavior were investigated when the input source voltage abruptly changed as a step function. Based on the comparison study with other DC-DC converters, the DSSB converter outperforms currently known DC-DC converters such as Buck, SEPIC, Boost, Buck-Boost, and other SEPIC converter topologies in terms of voltage gain, harmonic content, normalized current ripple, dynamic performance, and efficiency. Additionally, the frequency response and control of the proposed converter using an alternate current (AC), small-signal, analysis-based, current-mode control technique are both provided. Thus, the DSSB is regarded as safe in overcurrent situations because of the small-signal analysis with the current control strategy. As a result of the verification of the proposed control technique, the resistance to changes in the DSSB parameters, improved dynamic performance, and higher control accuracy are further advantages of current-mode control based on small-signal analysis over other control approaches (PI controllers). Finally, the experimental and simulation results from Simplorer 7 and MATLAB/Simulink are used to validate the findings of the analytical and comparative investigation.

DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create instability in the DC power system, lower its efficiency, and shorten the lifetime of the DC source. This paper presents a general waveform control method that can mitigate the injection of the low-frequency ripple current by the single-phase DC/AC inverter into the DC source. It also discusses the inhibiting ability of the waveform control method on other coexisting harmonics, while the DC source delivers AC power to a nonlinear load. With the application of the waveform control, the average DC output power is supplied by the DC source, while the other harmonics pulsation power can be confined to the AC side (between the capacitors and the AC load). Theoretical analyses and experiment results are provided to explain the operation and the inhibiting ability, and to showcase the performance of the approach in tackling the harmonics. Results validate that the proposed solution can achieve significant mitigation of harmonic component at DC side with nonlinear load as well as a high quality output voltage without the need for extra large capacitive energy storage element implementation.

This work has adopted the concept of asymmetric inductor magnetization to develop a new quadratic converter with the advantages like a wide range quadratic voltage gain and low source current ripple. In addition, the proposed high quadratic converter has achieved reduced voltage stress due to the presence of switched capacitor cell at the output side. Initially, the operation of the converter and steady-state analysis, including efficiency calculations, are explained. In addition, the design and selection of converter components are presented along with a small-signal analysis. Further, a comprehensive comparison with recent high quadratic gain converters is presented. The comparison is made with regard to the total component count, voltage conversion ratio, effectiveness index, electric stress, current ripple, switching device power (SDP) rating, and input current ripple factor. Furthermore, the 150 W laboratory prototype is used to verify the performance of the proposed converter in terms of operation, dynamic response, and efficiency, and the corresponding experimental findings are reported. The wide range voltage gain, low current ripple, and low electric stress features of the proposed converter highlight its superiority in fuel cell electric vehicle applications.

This paper studies a modified DC-DC boost converter where the input inductance has been replaced by an LCL filter. The voltage conversion ratio of the proposed converter is equivalent to the conversion ratio of a conventional boost converter, and it has only one active switching device. A controller is proposed to regulate the output voltage to a given reference with guaranteed reduced input current ripple, i.e., high-frequency current components are minimized at the input current source. Low current ripple is required when dealing with sensitive electric power sources such as fuel cells, batteries and electrolytic capacitors used at DC-links in power electronics applications. The controller design follows a Lyapunov approach, and provides active damping to the input LCL filter. Numerical simulations are presented to evaluate the closed-loop performance.

This paper proposes novel bidirectional DC-DC converter that has the advantages of high voltage gain, low conduction losses and low input current ripple. Two paralleled current-fed full bridges are located in the low voltage side (LVS), sharing one voltage-fed full bride in high voltage side (HVS). A quadruple phase-shift control strategy is proposed to reduce input current ripple and conduction loss. The phase shift between the full-bridges of LVS is employed to greatly reduce current ripple and the auxiliary inductors are used to help the lag bridge extend the zero-voltage-switch (ZVS) range. Finally, an 800W simulation prototype is built to verify the proposed converter, the accordance between the analysis and simulation results testify the advantages.

An isolated four channel dc/dc converter with zero voltage switching is proposed as the front-end of multiple inverter structures to integrate renewable and other low voltage energy sources to micro grids. The interleaving technique is adopted to connect each module of proposed converter to a common dc source. This dc source can be a fuel cell stack, PV panels, battery, or any other low voltage dc source. All four channels are interleaved and a phase shift of 90° is provided between the gate signals of each channels, which reduces the input current ripple. The output port of the proposed converter provide four isolated and regulated dc voltages. These isolated dc sources can be connected in series or parallel or series-parallel manner to obtain required dc-link voltage of various inverter structure. Issues like capacitor voltage balancing of diode clamped multilevel inverters can overcome through the proposed converter. By incorporating a coupled inductor for isolation and energy storage along with voltage multiplier circuit, the proposed converter can achieve higher voltage step up with lower turns ratio and lower voltage stress at moderate duty ratio. Hence, mosfets of low voltage rating (low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> (ON)) can be utilized to reduce conduction loss. A 2 kW prototype of the proposed interleaved dc/dc converter is developed and tested with diode clamped three-level inverter, five-level inverter, and three-phase two-level inverter to verify the design.

In this paper, a new single-phase five-level grid-connected switched capacitors (SC) inverter with LCL filter has been presented. It comprises nine unidirectional switches, one discrete diode, one switched capacitor and one DC source. At the end of an inverter output, the LCL filter has been integrated with grid. Basically, the LCL filter provides greater ripple attenuation capability as compared with L and LC filters. Based on parallel-series technique, the topology provides self-balancing property of SC and also gives two times boosting ability with single DC source arrangement. The topology also provides less per unit total standing voltage (TSV) and maintains uniform voltage stress among all semiconductor devices. Before going to grid connection, the level output with RL load case has been checked with proposed universal rounding control scheme (URCS), and it is the modified version of nearest-level control (NLC) technique. In grid-connected case, the dq frame current control strategy and unipolar phase disposition (UPD) pulse width modulation (PWM) techniques have been applied. With step changes in direct axis current reference values, the unity power factor (UPF) operation of grid has been elucidated. Finally, the operation and control strategies with both RL load- and grid-connected cases have been validated through MATLAB/Simulink platform.KeywordsUniversal rounding control schemeSwitched capacitorTotal standing voltageUnity power factorPulse width modulation

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.

In this paper, a novel non-isolated interleaved DC/DC boost converter is presented in which coupled inductors and a passive clamp circuit are employed. ZCS turn-on condition for main switches is provided, and the stored energy in leakage inductance is recycled by means of a passive clamp circuit. Therefore, the voltage stress across switches is reduced resulting in circuit efficiency improvement. Due to interleaved structure and cross-coupled inductors, the input current ripple is reduced and the input current is continuous. To achieve ZCS turn-on condition, the intrinsic leakage inductance of the coupled inductors is used which leads to improving the power density and reducing the switching losses. In order to confirm the theoretical analysis, a prototype with 30 V input voltage, 300 V output voltage, and 300 W is implemented and tested.

An interleaved buck-boost converter with a wide conversion ratio is proposed in this paper. Two converter cells are used in the porposed converter. One is a single-ended primary inductor converter (SEPIC) and the other is a Cuk converter. Since both converter cells have an inductor and a switch, the input current of the proposed converter has low current ripple by utilizing an interleaving technique. The SEPIC converter cell provides a positive step up/down output and the Cuk converter cell provides a negative step up/down output. Therefore, the proposed converter has also step up/down capability and a wide conversion ratio. The proposed converter has a low input current ripple, step up/down capability, and a wide conversion ratio. Theoretical analysis and performance of the proposed converter were verified on an experimental prototype operating at 100 kHz switching frequency.

Small Signal Modeling of a DC-DC Type Double Boost Converter Integrated With SEPIC Converter Using State Space Averaging Approach

Solar panel is widely used as an alternative source to generate solar power plant. One of the ways to store solar panel power is by saving the power on a battery. Generally, the efficiency of solar panel is about 15% - 24.7%. It is quite small because the use of solar panel without control causes the power plant not maximum. In this paper, Modified Particle Swarm Optimization (Modified PSO) was proposed for MPPT control to optimize solar panel power. The algorithm of this method was used to increase efficiency of solar cell so that the power can reach maximum point. Furthermore, the power was used to optimize battery charging process. To verify the performance of Modified PSO algorithm, it was used SEPIC Converter as interfacing from solar panel to battery. Based on the experiment result on three shading patterns for 3 hours charging process, the increase of State of Charge (SOC) of the battery using Modified PSO algorithm was superior than uncontrolled and conventional method (Perturb and Observe).

Input current and its ripple of the interleaved boost converter with arbitrary number of phases are analyzed in details and the formula of quantifying input current and its ripple are derived. As a result, a new control approach of adjusting the active phase number and switching frequency to achieve the low or even zero input current ripples in the interleaved boost converter is proposed. Therefore the input filter can be significantly decreased on size and cost or even not needed in steady-state. In addition, the practical factors that affect the input current ripple are presented. Simulation and experimental results show that the input current ripple can be greatly decreased with this approach. Moreover, the principle of this control approach is also valid for other common interleaved dc-dc topologies.

In this paper an instantaneous maximum power extraction scheme is proposed as a PV power optimizer. The presented power harvesting scheme is rely on a weather-based power forecasting model in which the instantaneous value of the maximum power that should be extracted from the individual PV module is computed. The control unit of the proposed dc power optimizer is composed of a PI power controller and a PWM unit driving a SEPIC converter as a power conditioner. The chopper duty cycle is continuously adjusted such that the PV module is forced to operate near the maximum power point that is determined from the online measurements of the meteorological data model. The system is studied under both step down and step up modes of operation permitted by the SEPIC converter. The proposed scheme is investigated under different patterns of solar irradiance. The obtained results indicate both fast transient response and the good accuracy with low computation complexity due to the simple meteorological data model of the PV module. Compared with the commonly used perturb and observe (P&O) technique, the proposed scheme has better performance in terms of lower peak-peak power ripple. However, it has relatively lower tracking efficiency of (1–2)% due to the intentional reduction in the reference power signal to guarantee the fact that the actual harvested PV power can't exceed the reference value determined by the weather based model. The application area of the proposed scheme would be extended from a dc power optimizer for an individual PV to include microgrid applications, where commercially available temperature and solar irradiance transducers can be embedded with the distributed control unit of the SEPIC converter without dramatic increase to the initial cost of the overall system.