Two-switch Buck-boost Converter Research Articles

Three-mode switching control Strategy based on Two-Switch Buck-Boost converter

The Two-Switch Buck-Boost (TSBB) converter can adjust a wide voltage range and is widely applied in the field of aerospace power supply. According to the energy relationship among the output power of the solar array, battery, and load, the converter can operate under three different modes. To solve the problem that the input voltage is clamped in the process of battery charging and the maximum power point tracking (MPPT) of the solar array is affected, a smooth switching control strategy between three modes is proposed in this paper. The operating mode of the current converter is determined by the variation of the current integral on the output capacitor, and it is used as the condition for the converter to exit the pass-through (PT) mode. In this way, the fast and stable switching between modes can be realized, and the dynamic response of the converter can be effectively improved. In addition, in order to avoid the input voltage disturbance affecting the output characteristics, this paper proposes a closed-loop control design based on input voltage feedforward control. Plecs simulation results show that the proposed loop control strategy has good stability and reliability.

Modified Design of Two-Switch Buck-Boost Converter to Improve Power Efficiency Using Fewer Conduction Components

In this study, a modified design of a two-switch buck-boost (TSBB) converter is proposed to improve power efficiency using fewer conduction components, and the optimal power range is measured. The proposed TSBB converter operates in three topologies: buck, boost, and buck-boost, like the conventional TSBB converter. However, the proposed converter improves the power efficiency in the buck and buck-boost topologies by decreasing conduction loss using the diode in the switch-off section while maintaining the same number of semiconductors as that in the conventional TSBB converter. The power efficiency of the buck topology improves for the power range 10–80 W in the constant voltage (CV) and constant current (CC) modes; it increases on average by 0.75–1.36% and 0.83–2.27% in the CV and CC modes, respectively. The power efficiency of the buck-boost topology step-down improves for the 10–80 W in all modes. This increases the average by 0.73–0.99% and 3.33–4.75% in the CV and CC modes, respectively. The power efficiency of the buck-boost topology step-up increases on average by 1.65–2.00% for 10–80 W in the CV mode. In the CC mode, it increases by 2.17–2.77% on average for 10–50 W.

Current Mode Control of Non-Isolated Multi-Phase Interleaved Buck-Boost Converter for Military Battery Charging Application.

Power conversion devices are essential in a remote off-grid site, typically for military purposes where several types of equipment with varying input characteristics are supplied essentially by the same energy source, necessitating the use of a buck-boost converter for DC-DC applications. Because the conventional buck-boost converter's inverting output voltage is incompatible with some applications, the two-switch buck-boost converter is recommended for battery charging in military applications. The nominal input voltage range of the five-phase interleaved buck-boost converter is 9 – 36 V, the output voltage is 28 V, the output power is 3.3 kW, and the switching frequency is 100 kHz. The simulation of the converter with current mode control in the MATLAB/Simulink simulation environment was performed to confirm validity of the operational theory and the simulation results show consistency with theoretical values. Maximum of 74.41 ms and 51.35 % were recorded under all conditions of operation for the settling and overshoot respectively. The obtained data indicates a 1–2 % variation between the measured and theoretical duty cycle.

Pulsed-Supplied Water Electrolysis via Two-Switch Converter for PV Capacity Firming

Hydrogen constitutes the only carbon-free fuel that can be used for energy conversion, producing water as the only by-product. With water being one of the most abundant and inexhaustible raw materials in the world, and the required electricity input being provided by renewable resources, the produced hydrogen via water electrolysis constitutes a green pathway towards sustainability. In this work, a hybrid PV power-to-hydrogen, storage and fuel cell system is proposed to satisfy the domestic load of a residential building. Identifying alkaline as a mandatory electrolysis technology, the performance of alkaline electrolysis cells is assessed considering the inclusion of a two-switch buck-boost converter. Following a comprehensive formulation with respect to each distinguished system component, the balance condition at DC and AC buses is determined. The proposed configuration is evaluated, taking into account PV systems of different ratings, namely 3 kW, 5 kW and 7 kW. Based on actual data relating to both PV generation and domestic load for the year 2020, the obtained results from the annual simulations are compared with feed-in tariff and net-metering schemes. According to the results, PV capacity firming is achieved, creating great opportunities for autonomy enhancement, not only for electricity, but also in other energy sectors.

A Transformer-Less Buck-Boost Grid-Tied Inverter with Low Leakage-Current and High Voltage-Gain

To improve the efficiency of photovoltaic (PV) grid-tied systems and simplify the circuit structure, many pseudo DC-link inverters have been proposed by combining a sinusoidal pulse-width modulation (SPWM) controlled buck-boost converter and a low-frequency polarity unfolder. However, due to the non-ideal characteristics of power diodes, the voltage-gain of a buck-boost converter is limited. To meet the needs of grid-connected systems with low input voltage and 220 Vrms utility, this paper uses two two-switch buck-boost converters with coupled inductors to develop a transformer-less buck-boost grid-tied inverter with low leakage-current and high voltage-gain. The proposed inverter is charging on the primary side of the coupled inductor and discharging in series on the primary side and the secondary side so that the voltage-gain can be greatly increased. Furthermore, the utility line can be connected to the negative end of the PV array to suppress leakage current, and the unfolding circuit can be simplified to reduce the conduction losses. High-frequency switching is only performed in one metal-oxide-semiconductor field-effect transistor (MOSFET) in each mode, which can effectively improve conversion efficiency. A prototype was implemented to obtain experimental results and to prove the validity of the proposed circuit structure.

Dual output DC-DC quasi impedance source converter

A double output port DC-DC quasi impedance source converter (q-ZSC) is proposed. Each of the outputs has a different voltage gain. One of the outputs is capable of bidirectional (four-quadrant) operation by only varying the duty ratio. The second output has the gain of traditional two-switch buck-boost converter. Operation of the converter was verified by simulating its responses for different input voltages and duty ratios using MATLAB SIMULINK software. Its average steady-state output current and voltage values were determined and used to determine the ripples that existed. These ripples are less than 5% of the average steady-state values for all the input voltage and duty ratio ranges considered.

Design and implementation of a 22 kW full-bridge push–pull series partial power converter for stationary battery energy storage system with battery charger

A wide variety of AC/DC power converter topologies have been developed in order to improve the system efficiency, input power factor and system redundancy for stationary battery energy storage systems. Due to the nature of high-power batteries, there is a big voltage difference between battery terminals from the end of discharge to the high charge value. To prevent unregulated battery voltages from harming the system loads, several techniques are used in the industry. A well-known old technique named as diode dropper is simple but suffers from low efficiency. Using a DC-DC converter is more advantageous, although it increases the cost. In this paper, the use of partial power processing converters which attract interest these days has been proposed as an alternative. The proposed full bridge/push-pull series connected partial power converter has a slight modification compared to the classical one presented in the literature. A system with 22 kW power rating was designed and tested. In order to compare the results, a two-switch buck-boost converter was also designed and tested for the same conditions. The results show that the proposed converter is superior to both the two-switch buck-boost converter and other topologies in terms of efficiency and response speed. Efficiencies of 97%–99% have been attained with the proposed converter.

Design of a high-power density energy system for solar powered aircraft

Maximum energy utilization and high-power density are critical to solar powered aircraft energy system. SiC devices have the advantages of high frequency and high temperature and it is very promising in the aspect of the development of high temperature and high-power density converter. This paper designed a 1.2 kW SiC based power controller using interleaved two-switch buck-boost converter, analyzed the working process of the converter, put forward small signal model and discussed three mode control strategy, and achieved smooth switching among all modes and maximum utilization of power energy. Experimental results demonstrate that the converter module has the power density of 2.4 kW/kg.

A New Circuit Design of Two-Switch Buck-Boost Converter

A conventional two-switch buck–boost (TSBB) converter can operate in buck, boost, and buck–boost modes. This paper introduces a new topology for a two-switch buck–boost converter with the same operation modes. However, the proposed TSBB converter has fewer conductions and switching components than the conventional TSBB converter, which reduces the power losses.

A New Buck–Boost Converter With Low-Voltage Stress and Reduced Conducting Components

This paper presents a new buck–boost converter. Unlike the single-switch buck–boost converter, the proposed converter has low-voltage stresses on semiconductors. Moreover, although both the conventional two-switch buck–boost (TSBB) and the proposed converters have the same number of passive and active components, and the proposed converter can reduce the conduction loss as a result of having fewer conducting components. Therefore, the proposed converter obtained a higher efficiency than the TSBB converter. A 48-V output voltage and 150-W output power prototype was fabricated to verify the effectiveness of the proposed converter.

A Modified Topology of Two-Switch Buck-Boost Converter

Two-switch buck-boost (TSBB) is one of the non-isolated dc-to-dc converters that can change its mode from among buck, boost, and buck-boost modes. Changing its mode is possible by controlling gate signals. This paper presents a novel modified topology of TSBB converter. Even if the proposed converter has the same number of components as a conventional TSBB converter, the proposed converter has fewer conduction components and switching semiconductors than a conventional TSBB. This results in reduced power loss. Moreover, source terminals of metal-oxide-semiconductor field-effect transistor in the proposed converter are directly connected to ground. This configuration has an advantage in selecting gate driver integrated circuit (IC), since the IC does not necessarily need to provide high-side gate signals. A printed circuit board was designed to evaluate the improvement of the proposed converter.

A Family of Isolated Buck-Boost Converters Based on Semiactive Rectifiers for High-Output Voltage Applications

A systematic method for developing isolated buck-boost (IBB) converters is proposed in this paper, and single-stage power conversion, soft-switching operation, and high-efficiency performance can be achieved with the proposed family of converters. On the basis of a nonisolated two-switch buck-boost converter, the proposed IBB converters are generated by replacing the dc buck-cell and boost-cell in the non-IBB converter with the ac buck-cell and boost-cell, respectively. Furthermore, a family of semiactive rectifiers (SARs) is proposed to serve as the secondary rectification circuit for the IBB converters, which helps to extend the converter voltage gain and reduce the voltage stresses on the devices in the rectification circuit. Hence, the efficiency is improved by employing a transformer with a smaller turns ratio and reduced parasitic parameters, by using low-voltage rating MOSFETs and diodes with better switching and conduction performances. A full-bridge IBB converter is proposed and analyzed in detail as an example. The phase-shift modulation strategy is applied to the full-bridge IBB converter to achieve IBB conversion. Moreover, soft-switching performance of all active switches and diodes can be achieved over a wide load and voltage range by the proposed converter and control strategy. A 380-V-output prototype is fabricated to verify the effectiveness of the proposed family of IBB converters, the SARs, and the control strategies.

Buck/Boost DC

In this paper, a dc link voltage variable inverter system is proposed, which consists of a two-switch buck-boost converter and a four-switch inverter. In addition, as the current and torque ripples are generated by a voltage difference between back EMF and dc link voltage, these ripples could be reduced according to the controlled dc-link voltage according to the motor speed. The validity of the proposed inverter is verified by informative simulation and experimental results.

Efficiency improvement on two‐switch buck‐boost converter with coupled inductor for high‐voltage applications

With two controllable switches, the efficiency of the two-switch buck-boost converters can be optimised by adopting appropriate control schemes. Among the control schemes, when only one switch works at high frequency, losses of the converter can be reduced effectively, but the complicated control logic and compensation technique are needed for step-up/down smooth transitions; when both switches operate at high frequency, the efficiency of these converters are low for high-voltage applications because of the serious switching losses. In this study, the coupled inductor is introduced to reduce the switching losses of these converters for high-voltage application and an asynchronous control scheme is proposed to reduce the losses much more. Based on the designed prototype, theoretical calculation, experiment results and loss analysis are provided to compare the traditional converter adopting single-winding inductor and the proposed circuit with the coupled inductor. And the comparisons of the converter adopting coupled-inductor with the tradition synchronous control scheme and that with the proposed asynchronous control scheme are also presented. The analysis and experimental results show that the efficiency of the converter adopting coupled inductor with the proposed asynchronous control scheme is the highest one. Moreover, the smooth transitions between step-up and step-down are also guaranteed by the proposed asynchronous control scheme.

A Two-Mode Control Scheme With Input Voltage Feed-Forward for the Two-Switch Buck-Boost DC–DC Converter

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.

Analysis and design of a low-stress buck-boost converter in universal-input PFC applications

In converters for power-factor-correction (PFC), the universal-input capability, i.e., the ability to operate from any ac line voltage world-wide, comes with a heavy penalty in terms of component stresses and losses, and with restrictions on the dc output voltage. In this paper, we propose a new two-switch topology, boost-interleaved buck-boost (BoIBB) converter, which can offer significant performance improvements over single-switch buck-boost converters (including flyback, SEPIC, or Cuk topologies) or other two-switch buck-boost converters in universal-input PFC applications. The paper presents an analysis of the converter operation and component stresses, as well as design guidelines. High efficiency (over 93%) throughout the universal-input ac line voltage range is demonstrated on an experimental 100-W, 200-V dc output, universal-input BOIBB PFC rectifier.

Current programmed control of a single-phase two-switch buck-boost power factor correction circuit

This paper presents a new current programmed control (CPC) technique for a cascaded two-switch buck-boost converter suitable as a low-cost power factor correction (PFC) rectifier in a variable speed motor drive. This new CPC technique, which is an extension of the conventional CPC method, enables the variable output dc voltage, and is therefore suitable in a pulse amplitude modulated (PAM) motor drive or as a universal input-power supply. The CPC method is very simple and requires only a constant-current reference without any changes in the transition between boost and buck operating mode, and the line current is practically unaffected by the topology-mode shift. Simulations and experimental results verify the presented control technique. Compliance with IEC-61000-3-2 class A is achieved. The experimental setup is based on a commercial CPC integrated circuit (IC) for dc-dc converters. This new control technique enables a simple low-cost control circuit for the two-switch buck-boost converter, which complies with IEC-61000-3-2, and the PFC circuit has inherent in-rush and overcurrent protection.