Highly efficient Capacitive De-Ionization (CDI) water purification system using a buck-boost converter

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.

This paper presents the study on the impedance matching method in two-stage converters for single phase PV-grid system. The use of PV systems was to obtain the electrical power from the sunlight energy. The system consisted of a Buck-Boost DC-DC converter and a five-level inverter. A Buck-Boost DC-DC converter was used as a means of impedance matching to obtain the maximum power that, in this case, through a method by using the incremental conductance current control algorithm. Meanwhile a five-level inverter was used as an interface to the utilities. By using this technique, the system came to be simple. The impedance of the power grid, a Buck-Boost DC-DC converter, and a five-level inverter were seen by PV mostly in the area of R<sub>MPP</sub>, enabling the maximum power produced by the PV to be delivered to the grid. To demonstrate the effectiveness of the design, the analysis and simulation results, furthermore, were provided

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.

In this paper, a new quasi-Y source buck-boost dc-dc converter is proposed. The proposed converter uses a quasi-Y impedance network, which consists of a three-winding transformer, or three tightly coupled inductors. The proposed converter inherits all the advantages of the original quasi-Y source dc-dc converter such as continuous input current, lack of saturation in the magnetic core of the transformer, small duty cycle and high gain. The advantage of the proposed converter is adding the buck-boost ability to the conventional structure, which is crucial for some applications such as wind turbines and battery charging systems, which demand a buck-boost converter in their structure. The mathematical analyses are provided in order to investigate the operation principles of the converter. Also, in order to verify the proper functioning of the proposed converter, simulations are done in PSCAD/EMTDC and the results and waveforms are provided in the paper.

This paper is a review on 4 phase 8/6 switched reluctance motor (SRM) powered by solar PV array using the buck-boost dc-dc converter. The water pumping system is operating SRM. The main objective of this paper is to regulate the speed of SRM drive to pump the water through the DC link voltage of a mid-point converter. The split capacitor converter for SRM drive called as mid-point converter is electronically commutated to reduced switching losses. This motor is inexpensive, reliable and efficient than conventional DC and AC electrical machines used in this application, because of its simple construction. The losses in mid-point converter can be reduced by using SRM drive at its fundamental frequency and also the efficiency of the proposed system can be increased. The DC-DC buck-boost converter is working in continuous conduction mode (CCM). The CCM operation decreases the losses of DC-DC converter. The soft starting of 4 phase 8/6 SRM drive is also achieved through proper selection of step-size in incremental conductance (InC) algorithm method of maximum power point tracking (MPPT). The DC-DC buck-boost converter is the unique converter which allows excellent tracking of PV array maximum MPP rather than of temperature and insolation levels.

A novel buck-boost dc-dc converter with high voltage step-up and step-down ability has been introduced in this paper. There are two switches in this converter, of which the sources are connected together and also connected to the ground of the input voltage source. Hence, there is no need for floating gate driver. In addition, the voltage stress of one of the switches is lower than the existing quadratic buck-boost converters. Performance of the analytical results is validated using both simulation in MATLAB/SIMULINK and experimental tests where the proposed converter is evaluated in both buck and boost modes.

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 proposed a novel isolated buck-boost PWM DC-DC converter circuit. The topology which merged buck-boost mode with flyback mode can share the transformer and switch. Not only isolated buck-boost mode current but also flyback mode current added on the one output current of the converter because the topology merged buck-boost mode with flyback mode. A new converter has outstanding advantages over the conventional dc-dc converters with respect to high efficiency, high power density, and component utilization. The operation principle of the proposed converter is described and verified by simulation and experiment results. Also this paper presents novel circuit and simulation result of new active isolated buck-boost converter.

This paper presents a hybrid buck-boost DC-DC converter structure to address the limitations of single-output and low conversion ratios (CR) in traditional energy harvesting systems. To reduce the CR of the inductive boost and enhance the total CR of the converter while improving efficiency, the proposed converter cascades a boost circuit with a reconfigurable switched capacitor (SC), and also includes a supercapacitor. The advantage of this architecture is the ability to use low-voltage low-threshold transistors with lower parasitic capacitance and on-resistance, which achieve high-voltage output while reducing switching and conduction losses. The supercapacitor can store energy under a light load and provide additional energy replenishment in buck mode under heavy load. The reconfigurable SC circuit can enable a 2V or 3V output by configuring the switch array. Adaptive switching frequency control was used to achieve a balance between load capability and switching loss. The proposed DC-DC converter is designed with a 0.18 µm CMOS process and has maximum conversion efficiencies of 91.83%, 89.42%, and 88.09% for the inductive boost stage, 2V SC output stage, and 3V SC output stage, respectively. The output voltage ripple is less than 20 mV at 1V output and less than 30 mV at 2V output and 3V output. The input voltage of the converter is as low as 20 mV. The converter features multi-output, high-conversion-ratio, and enhanced efficiency, which are suitable for energy-harvesting applications.

A new step-up-down DC-DC converter architecture is proposed, which utilises the close inversely-coupled inductors topology in both its conversion stages (bucking and boosting stages). The new converter aims to reduce the switching noise by reducing the back e.m.f induced in the main inductor by maintaining a continuous current through it and delivered to the load. This results in an increase in a conversion efficiency for this kind of converter dealing with wide range of supply voltages and serves a wide variety of applications. Circuit configuration, principles of operation, transfer function, simulated results and the experimental results are presented. The proposed concept is verified by the experimental results of a range of cases studies.

DC microgrid based on photovoltaic (PV, 500 W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> ) and fuel cell (FC, 1 kW) power generators have been designed to operate DC loads at different voltage levels (24 V, 48 V and 110 V). The voltage level in a DC microgrid decides the system efficiency, voltage regulation and the total cost. The system efficiency is shown to depend on the power conversion mode (DCDC converter) efficiency and ohmic loss (in connecting cables). DC loads used vary from 250 W to 1000 W and according the cable sizing is required to be changed to improve the voltage regulation and to reduce the cable loss. The buck-boost DC-DC converter is used in 24/48 V microgrids, while boost converter is required for 110 V microgrid. The buck-boost converter efficiency is ≈ 85% and the boost converter provides efficiency ≈ 95%. It is shown that 110 V DC voltage level gives optimum performance for low power DC microgrid in comparison with 24 V or 48 V.

This paper presents a fully integrated single-inductor dual-output (SIDO) buck-boost or boost-boost DC-DC converter with power-distributive control. This converter works under voltage mode control to have better noise immunity, uses fewer power switches/external compensation components to reduce cost, and is thus suitable for system on chip (SoC) applications. The proposed SIDO converter was fabricated in TSMC 0.35μm 2P4M CMOS technology with input supply voltage 2.7–3.3 V. The first output V O1 can operates either at buck mode or boost mode (output voltage in between 2.5V to 5V), while the second output V O2 can only operates at boost mode (output voltage 3.6V).

Power Management Units (PMU) are rapidly being developed to provide a significant amount of power for sensors in Internet-of-Things (IoT) networks. This paper presents a novel optimized PMU design for IoT applications, which can be used as a part of energy harvesting system that can be composed of solar cells, wind turbine, thermal energy, and vibration. Hence the proposed design can be used as a feasible energy harvester, where notable power efficiency is achieved here over traditional PMU designs under the same circumstances. The optimized PMU is developed using a buck-boost DC-DC converter. The particle swarm optimization (PSO) is then applied to optimize the parameters of PMU, including buck-boost DC-DC converter, and control circuitry to achieve maximum power point and improve the overall efficiency.

In this paper fully integrated single switch DC-DC Buck-Boost Converter is designed and implemented for photovoltaic (PV) applications. Buck-Boost Converter is employed to transform the unregulated DC supply from the PV system to a regulated output voltage. Conventional switching of converters leads to power losses during switching there by reducing the efficiency of the system. In this work Zero Voltage Source (ZVS) based soft switching is employed to buck boost converter without using auxiliary switches. A 200 W prototype model was designed, simulated in PSPICE and realized in hardware. The experimental results were found to be satisfactory.

A novel switching structure formed by an externally controlled switch, a coupled inductor, and two synchronous switches (diodes) is proposed. The practical implications of the leakage inductance are considered. This structure is inserted into PWM DC-DC buck, boost, and buck-boost converters by replacing their switch and inductor. The results are new converters with very high step-up or step-down voltage gain. The new switching-mode power supplies are analyzed in steady-state. The energy accumulated in the leakage inductance is transferred to the output capacitor in a non-oscillatory manner. The influence of the magnetically-coupling coefficient on the dc gain is studied. Simulation and experimental results confirm the theoretical analysis and the advantages of the proposed converters