Modified Switched-Inductor Based DC-DC Buck-Boost Converter for Low-Power Applications

The FC sources are unregulated voltage sources and require power converter devices to get a regulated output voltage. When these devices are used in low voltage low power applications DC-DC buck-boost converters (BBC) are required to get the regulated voltage on load side. The multi device multi switch operation of the buck-boost converters are usually employed for successful operation of the FC stacks. In this paper, the different non-inverting type of buck-boost converters i.e., buck-boost converter (BBC), multi-device buck-boost converter (MDBBC), interleaved buck-boost converter (IBBC), and multi-device interleaved buck-boost converters (MDIBBC) are analysed and comparative study among them are presented with respect to the parameters like, ripple current, component size, power losses and efficiency. The comparative study demonstrates that the multi device converter topologies are more efficient than the other converter topologies employed in low voltage low power applications.

This paper studies boundary control for a multiple-input buck-boost (MIBB) converter topology with equal voltages at each input leg. In addition to not requiring different input voltages as in previously suggested MIBB converters, when input voltages are equal the proposed controller eliminate the need for forward-conducting bidirectional-blocking switches (FCBBs) also present in previous MIBB topologies. The prescribed controller makes the closed loop MIBB system to behave as a single-input buck-boost converter so that a solution to in the sense of Filippov can be defined in reflective mode. Large-signal asymptotic stability of the desired operating point is subsequently established using Lyapunov's direct method. The state-dependent switching strategy presented ensures that the system avoids certain limitations that occur when multiple-input converters that operate based on switching period-sharing. These restrictions include different input voltages, and limited number of input legs. A lower parts count and better efficiency may then be achieved. Robustness and other attributes of boundary control make the proposed strategy favorable. Both pros and cons of the proposed scheme are discussed and design recommendations are given. The analysis is verified by simulations and an experimental setup with four input legs.

This paper proposes a new topology for multi-input multi-output Buck-Boost DC-DC converter based on the concept of matrix and Buck-Boost Converters to interface efficiently between DC loads and various DC power sources in a microgrid. A power sharing process can be applied among the input sources and output loads to control the contribution of each input sources in supplying the output loads. The input sources can be used in various power and voltage ranges and the output voltages can change from values greater than the maximum to lower than the minimum input voltages. Theoretical analysis and simulation results are presented.

Buck-boost DC–DC converters are useful as DC grid interfaces for renewable energy resources. In the classical buck-boost converter, output voltages smaller than the input voltage (the buck region) are observed for duty cycles between 0 and 0.5. Several recent buck-boost converters have been designed to present higher voltage gains. Nevertheless, those topologies show a reduced duty-cycle range, leading to output voltages in the buck region, and thus require the use of very low duty cycles to achieve the lower range of buck output voltages. In this work, we propose a new buck-boost DC-DC converter that privileges the buck region through the extension of the duty-cycle range, enabling buck operation. In fact, the converter proposed here allows output voltages below the input voltage even with duty cycles higher than 0.6. We present the analysis, design, and testing of the extended buck-boost DC-DC converter. Several tests were conducted to illustrate the characteristics of the extended buck-boost DC-DC converter. Test results were obtained using both simulation software and a laboratory prototype.

A hybrid fuel cell system includes a fuel cell unit, a battery and/or a super-capacitor. A super-capacitor is a passive element, it is easily grasp the SOC state, but battery is difficult to determine the exact SOC state causing break by excessive charging and discharging. In order to resolve this problem, the hybrid fuel cell system utilizes the bi-directional dc/dc converter for battery protection by managing the battery charging and discharging. As a bi-directional converter is necessary to increase overall performance in the fuel cell vehicle application to cope with fluctuating load, a dc/dc bi-directional converter is expensive and complicated to control. This study presents the simple dc/dc buck-boost converter topology in the fuel cell hybrid system which has small load variations.

Single-switch step-up/step-down converters, such as the buck-boost, SEPIC and Cuk, have relatively high voltage and current stresses on components compared to the buck or the boost converter. A buck-boost converter with two independently controlled switches can work as a boost or as a buck converter depending on input-output conditions, and thus achieves lower stresses on components. Using the converter synthesis method from D. Zhou (1995), families of two-switch buck-boost converters are generated, including several new converter topologies. The two-switch buck-boost converters are evaluated and compared in terms of component stresses in universal-input power-factor-corrector applications. Among them, one new two-switch converter is identified that has low inductor conduction losses (50% of the boost converter), low inductor volt-seconds (72% of the boost converter), and about the same switch conduction losses and voltage stresses as the boost converter.

enhancing the voltage ratio in a converter is a leading aim to improve its performance. Regarding this goal, this paper proposes a new topology of buck-boost converter. The proposed converter offers a much higher voltage gain ratio in comparison to its relevant high gain buck-boost structures. The range of duty cycle has widened in this converter without adopting any transformers or coupled inductors in its configuration. The number of components is quite a few. Therefore, this converter is quite easy to be controlled. Furthermore, the common electrical ground between the input and output ports of the presented converter has preserved. Hence, this structure is an appropriate choice to be utilized in several industrial applications. Calculations of voltage and current have made for this converter. The amount of each component has designed. The proper performance of this topology has evaluated and validated by PSIM Simulink software.

<p>This proposal proposes a DC/DC Buck Boost converter which has been used as a smooth starter for a DC Permanent Magnet Motor. In the existing system the DC/DC Buck Converter is used which provide the output less than the input Signal. Using buck converter it is difficult to increase the value of the input signal. Hence DC/DC Buck- Boost Converter used from which it is possible to get both the increased and decreased output from the given input. Previously pulse width modulation signals with respective to motor voltage is used. However they produce variations in the voltage and current of the motor. The above problem is overcome by using DC/DC Power converter. The proposed system with reduction in size, reduced ripples and increase in speed makes the system to operate at both low and high power applications. The proposed system results in higher efficiency, reduces the ripple content and the stress. The results are validated through MATLAB/Simulink and real time implementation.</p>

The buck-boost DC-AC inverter generates an alternating output voltage as the differential voltage of two DC-DC individual buck-boost converters that are driven with two 180/spl deg/ phase-shifted DC-biased sinusoidal references. The peak value of the inverter alternating output voltage does not depend on the direct input voltage. In addition, an advantage over the Boost DC-AC inverter is that the output voltages of both Buck-Boost converters are also independent of the direct input voltage. The difficulty of the topology lies in the control of both buck-boost DC-DC converters as they are required to work with variable operating-points. A double-loop control strategy is proposed for the buck-boost DC-DC converter with a new inner control loop for the inductor current and also a new outer control loop for the output voltage. These control schemes include different compensations that make possible a fast and accurate control of both converters with variable operating points. With these compensations, the controllers are easy to design, implement and develop. Furthermore, feedforward loops are included to increase the robustness of the inverter to external disturbances in both the input voltage and output load. The proposed control strategy is designed and implemented on a prototype 1.5 kW buck-boost DC-AC inverter. The control strategy is validated by means of both simulation and experimental tests. The results show that the proposed strategy achieves a robust, reliable and accurate control of the inverter even in hard situations such as nonlinear loads, sudden load changes and transient short circuits.

This paper presents a novel method for making Capacitive De-Ionizatrion (CDI) water purification more efficient and cheaper, using a buck-boost DC-DC converter. The energy recovery is superior (51%) versus maximum reported results in the literature (30%) [1]. First, the concept of a CDI cell is introduced. Second, the existing methods for energy recovery are reported showing their advantages and disadvantages. Then, the novel method using a buck-boost converter is presented. Simulation results are provided. Experimental data verified the new technique and agrees with simulation.

The purpose of this study is to perform research about newton-method control using buck-boost converter that is applied to photovoltaic system considering soft switching method. Because the photovoltaic cell's output is changed by insolation and temperature, it requires MPPT operating at maximum power point in photovoltaic application field. Thus DC-DC converter should be used to make photovoltaic cell's output work at maximum power point. In addition, in order to optimize the efficiency of the system was used soft switching buck-boost converter. For buck-boost converter loss reduction and efficiency optimization, Soft-switching converter have adopted the ZCS and ZVS method. In order to verify the feasibility of the proposed method, simulation was performed in line with Matlab-Simulink and Sim coupler and the results are proven.

This paper focuses on the non-inverting buck- boost converter operated as either buck or boost converter. It is shown that a pulse-width modulation (PWM) discontinuity around buck/boost mode transition can result in substantial increases in output voltage ripple. The effect of the PWM nonlinearity is studied using periodic steady state analysis to quantify the worst case ripple voltage in terms of design parameters. Furthermore, a bifurcation analysis shows that the PWM discontinuity leads to quasi- periodic route to chaos, which results in erratic operation around the buck/boost mode transition. The increased ripple is a very significant problem when the converter is used as a power supply for an RF power amplifier, as is the case in WCDMA handsets. An approach is proposed to remove the discontinuity which results in reduced output voltage ripple, at the expense of reduced efficiency, as demonstrated on an experimental prototype.

Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat. Solar energy is a vital untapped resource in a tropical country like ours. The main hindrance for the penetration and reach of solar PV systems is their low efficiency and high capital cost. Solar cell panels are exposed to sunlight at different angles and with variable intensity, therefore the resulting output power varies depending on the illumination angle as well as the light intensity of each panel. The MPPT is responsible for extracting the maximum possible power from the photovoltaic and feed it to the load via the buck-boost converter which steps up the voltage to required magnitude. The main aim will be to track the maximum power point of the photovoltaic module so that the maximum possible power can be extracted from the photovoltaic. This project investigates in detail the concept of DPSO algorithm under partial shading condition which significantly increases the efficiency of the solar photovoltaic system. To evaluate the idea, the algorithm is implemented on a buck-boost converter and compared to the conventional PSO method.

The development of capacitive power transfer (CPT) as a competitive wireless/contactless power transfer solution over short distances is proving viable in both consumer and industrial electronic products/systems. The CPT is usually applied in low-power applications, due to small coupling capacitance. Recent research has increased the coupling capacitance from the pF to the nF scale, enabling extension of CPT to kilowatt power level applications. This paper addresses the need of efficient power electronics suitable for CPT at higher power levels, while remaining cost effective. Therefore, to reduce the cost and losses single-switch–single-diode topologies are investigated. Four single active switch CPT topologies based on the canonical Cuk, SEPIC, Zeta, and Buck-boost converters are proposed and investigated. Performance tradeoffs within the context of a CPT system are presented and corroborated with experimental results. A prototype single active switch converter demonstrates 1-kW power transfer at a frequency of 200 kHz with >90% efficiency.

The paper outlines a case study on an integrated starter-generator-torque-booster (ISGtB) for automotive applications, representing an electric part of a hybrid propulsion system of a street scooter. Requirements for a high power density of the electrical machine led to a permanent magnet brushless DC machine (BLDC) with an external rotor. The complex functionality of the ISGtB, some deciding characteristics of modern two-stroke internal combustion (IC) engines and the nature of the selected electrical machine with linear dependence between back EMF and rotational speed dictate the properties and capabilities of the switch-mode power converter (SPC) that must support all operating modes of the ISGtB and bi-directional energy flow. The research work involved the extensive study on different suitable SPC topologies, including also control strategies, in the sense of starting torque, motor as well as generator operation mode of ISGtB. The selection of the SPC topology was made on the basis of theoretical statements, computer simulations and measurement results on several ISGtB prototypes. It consists of a bi-directional buck/boost converter and of a common known six-step inverter, as an executing stage. The topology of the bi-directional buck-boost converter is derived mainly with regard to the conversion ratio between the supply battery voltage level and DC link voltage level. The instantaneous value of the transferred electric power is tuned to the torque/speed characteristic of the IC engine and, in the opposite energy flow direction, to the requested output power in the generator operation mode. The deciding parameter when selecting the executing stage of the SPC was the torque/current ratio of the BLDC machine for different inverter topologies and phase winding connections. A particular attention was paid also to an efficient operation of the ISGtB on the boundaries of the operation range, such as providing a low impedance current path at the starting maneuver and extending the low-speed generator mode. The phenomenon of reverse conduction of MOSFET transistors was effectively employed, thus improving the overall SPC efficiency and extending the ISGtB operation range. Measurement results clearly reveal the functionality of ISGtB over the whole rotational speed range of the prototype set-up. The employment of reverse conduction of MOSFET transistors significantly influences the torque characteristic in the starter mode of operation. The proposed inverter control principle in the generator operation mode of the ISGtB evidently improve the transition from generator to torque-boosting operation mode.