Analysis of boundary control for a multiple-input DC-DC converter topology

This paper analyzes a multiple-input converter topology with boost and buck-boost input legs that serves to integrate several different distributed generation sources into a common system dc bus. The multiple-input converter is arranged in modules that hold the common parts and in sub-modules that contain each input leg component. The result is a flexible and easily scalable system suitable for renewable energy sources. When compared with traditional highly reliable systems, such as telecom rectifiers and standard microgrid architectures, the proposed converter is inherently more reliable. Power budget equations are derived and studied. The theoretical analysis is verified with simulations and experimental results.

This paper explores the feasibility of active clamping techniques in isolated time-sharing multiple-input converters. Additional losses caused by energy transfer into the input switches from the leakage inductance in the isolating coupled-inductor are addressed with a common active clamping leg for all input legs. An active clamping technique is applied to isolated time-sharing multiple-input converters to minimize the additional switching losses, and the paper also conducts an operational analysis of a dual-input isolated single ended primary inductor converter (2IISEPIC) with the active clamping technique. Zero-voltage-switching can be achieved on the first-turned-on input leg and the active clamping leg with proper driving strategy and circuit parameter settings. Discussions on the effect of the active clamping technique to a multiple-input converter and the components stresses of the 2IISEPIC with the active clamping technique have also been made to assist in the design of time-sharing multiple-input converters. A prototype of the 2IISEPIC with the active clamping technique is built for efficiency and stresses verification, and it is showed that 94% efficiency is achievable at 200W output power and the component stresses are significantly reduced, especially the voltage stresses on input switches. An absolute 6 % improvement over the efficiency of the same circuit without soft-switching techniques is observed.

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.

Many electronic power distribution systems have strong needs for highly efficient AC-DC conversion that can be satisfied by using a buck-boost converter at the core of the power factor correction (PFC) stage. These converters can regulate the input voltage in a wide range with reduced efforts compared to other solutions. As a result, buck-boost converters could potentially improve the efficiency in applications requiring DC voltages lower than the peak grid voltage. This paper compares SEPIC, noninverting, and versatile buck-boost converters as PFC single-phase rectifiers. The converters are designed for an output voltage of 200 V and an rms input voltage of 220 V at 3.2 kW. The PFC uses an inner discrete-time predictive current control loop with an output voltage regulator based on a sensorless strategy. A PLECS thermal simulation is performed to obtain the power conversion efficiency results for the buck-boost converters considered. Thermal simulations show that the versatile buck-boost (VBB) converter, currently unexplored for this application, can provide higher power conversion efficiency than SEPIC and non-inverting buck-boost converters. Finally, a hardware-in-the-loop (HIL) real-time simulation for the VBB converter is performed using a PLECS RT Box 1 device. At the same time, the proposed controller is built and then flashed to a low-cost digital signal controller (DSC), which corresponds to the Texas Instruments LAUNCHXL-F28069M evaluation board. The HIL real-time results verify the correctness of the theoretical analysis and the effectiveness of the proposed architecture to operate with high power conversion efficiency and to regulate the DC output voltage without sensing it while the sinusoidal input current is perfectly in-phase with the grid voltage.

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.

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.

Hybrid power systems continuously deliver power to the load from several renewable energy sources. For such systems, the use of a multiple-input converter (MIC) has the advantage of simpler circuit structure and lower cost, compared to the use of several single-input converters. By decomposing converters into basic cells, namely, pulsating source cells and output filters, a set of basic rules for generating multiple-input converter topologies is proposed. Specifically, two families of multiple-input converters are systematically generated. In the first family of MICs, all the input sources can power the load simultaneously or individually. In the second family, only one power source is allowed to transfer energy to the load at a time. Furthermore, some isolated MICs are simplified for reducing the complexity of the circuit configuration.

The four-switch buck-boost (FSBB) converter effectively reduces the average inductance current of FSBB when the input and output voltage is close to each other by using the four-mode operation, which alleviates the problem of limited duty cycle and low efficiency in the traditional control modes. However, the steady-state duty cycle mutation of FSBB with four-mode control will occur during mode switching, resulting in output voltage fluctuation. We analyzed the mechanism of duty cycle sudden change of four-mode control FSBB during mode switching, explored its influencing factors and governing laws, and proposed to use input voltage feedforward control to improve the smoothness of four-mode switching, so as to improve the response speed of output voltage when input voltage changes suddenly. The simulation results showed that after the input voltage feedforward control method was adopted, the four working modes can be switched smoothly in a wide input voltage range, the output voltage can be adjusted quickly, and the full load peak efficiency can reach 98%.

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.

This paper presents a three-phase buck-boost switchmode power converter that lowers the input harmonics drawn by a voltage source PWM inverter drive. The buck-boost power converter examined, rated with a 0.26 per-unit current and drawing 6% of the total drive input power, is connected in parallel with the drive's main diode bridge and LC filter. 94% of the drive power is drawn through the diode rectifier. The low electrical stresses associated with the buck-boost power converter, in addition to the small number of high frequency switching components, makes the drive topology robust, conducive to soft-switching techniques and lowers the generation of EMI-RFI. The rectifier topologies are suitable for regulating the DC voltage rails for 2-level and 3-level inverters. For 3-level inverter drives using a centre-tapped capacitor DC-rail, the proposed rectifiers can compensate for load imbalances and maintain equal voltage drops across the two DC-rails. Since the buck-boost switchmode power converter is separate from the main drive diode rectifier, the drive can continue to operate satisfactorily even if the buck-boost converter fails. This same feature makes the buck-boost converter unit suitable as a drive option or for retrofitting. The drive configurations examined in the paper are verified with experimental results and Spice simulations.

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.

Extended-output-voltage (EOV) buck-boost converter is the development of conventional buck-boost converter which has greater voltage gain. This topology could be used for several applications that require a wider output voltage range such as the utilization of renewable energy or other applications. However, the output voltage response characteristics of EOV buck-boost converter have a large overshoot and time to reach a steady state condition is quite long in open loop state. This condition will generate unexpected response during input voltage and load value changes. In order to produce the desired output voltage, the PID controller is used in this research. The parameters Ki, Kp, and Kd are obtained by using direct synthesis method. The converter will be modelled using state space averaging technique. From the simulation, the application of the PID controller on EOV buck-boost converter can improve the transient response of the output voltage and maintain the output voltage value remains stable at the specified value despite changes in input voltages and load.

As compared with parallel converters employing buck converters or boost converters, the analysis of multiple-input parallel switched-capacitor (SC) DC-DC converters is not sufficient. In this paper, a multiple-input parallel DC-DC converter designed by using SC techniques is proposed for mobile back-lighting applications, and handy theoretical formulas are given concerning the power efficiency and equivalent circuit. The proposed parallel converter consists of two different kinds of converter blocks: 1. a 1.5× step-up SC DC-DC converter employing an input voltage from a lithium battery and 2. a novel step-up converter employing an input voltage from solar cells. The proposed converter can offer the output voltage for display back-lighting from solar energy, because the proposed step-up converter can achieve not only a large step-up conversion ratio but also a wide input range. Hence, the proposed converter will enable us to realize a long battery life, reduction of heat, and so on. Furthermore, derived theoretical formulas will be helpful to estimate circuit characteristics, because theoretical results agree well with SPICE simulation results. The validity of circuit design is confirmed by simulations and experiments.

The two-switch buck-boost (TSBB) converter is suitable for wide input voltage applications. In order to achieve high efficiency over the entire input voltage range, the TSBB converter is operated in buck mode at high input voltage and boost mode at low input voltage. Such operation is called the two-mode control scheme. The objective of this paper is to propose an input voltage feed-forward (IVFF) method to reduce the influence of the input voltage disturbance on the output voltage. The small-signal models of the TSBB converter are built, and based on which, the IVFF functions under different operating modes of the TSBB converter are derived. The IVFF function in boost mode is simplified for easy implementation. The two-mode control scheme with IVFF compensation is then proposed for the TSBB converter, which realizes automatic selections of operating modes and the corresponding IVFF functions. Besides, nearly smooth switching between buck and boost modes is also guaranteed. For exhibiting the advantages of the proposed control scheme clearly, comparisons between the two-mode control with and without IVFF compensation have been presented in this paper, including the output signal of the voltage regulator and input-to-output voltage transfer function. Finally, a 250−500-V input, 360-V output, and 6-kW-rated power prototype is fabricated to validate the effectiveness of the proposed control scheme in the laboratory, and the experimental results show that the TSBB converter has an improved input transient response and high efficiency over the entire input voltage range with this proposed control scheme.

This paper presents a new topology of non-isolated DC-DC buck-boost converter for low-power applications based on an existing boost converter. In regulated low-power applications, DC-DC switching power converters undergo frequent mode-shift from buck to boost and vice-versa. At the overlap between input/outpnt voltage, the converters efficiency does not suffer significantly, but the wide input-voltage operating area compels the regulated converters to operate at extreme values of the duty cycle (close to 0 and 1) which causes lower efficiency. An effidenct switching converter is required specifically for low-power applications to have substantial voltage step-up and step-down without resorting to operating at extreme values of the duty-cyde. In this perspective, the proposed buck-boost converter ensures appredable voltage step-up and step-down due to switched-inductor phenomenon. An experimental prototype of 20W, 1A was designed to validate the topology, yidding full-load practical effidency of 90% and 85% in buck-mode and boost-mode, respectively.