Showing papers on "Buck–boost converter published in 2015"
02 Sep 2015
TL;DR: In this paper, a detailed design procedure is presented for a bidirectional CLLLC-type resonant converter for a battery charging application, and a 3.5kW converter is designed following the guidelines in the proposed methodology.
Abstract: In this paper, a detailed design procedure is presented for a bidirectional CLLLC-type resonant converter for a battery charging application. This converter is similar to an LLC-type resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional snubber or clamp circuitry. Because of soft-switching in all switches, very high-frequency operation is possible; thus, the size of the magnetics and the filter capacitors can be made small. To reduce the size and cost of the converter, a CLLC-type resonant network is derived from the original CLLLC-type resonant network. First, in this paper, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented for the CLLLC-type resonant converter. Design of this converter includes determining the transformer turns ratio, design of the magnetizing inductance based on ZVS condition, design of the resonant inductances and capacitances. Then, the CLLC-type resonant network is derived from the CLLLC-type resonant network. To validate the design procedure, a 3.5-kW converter was designed following the guidelines in the proposed methodology. A prototype was built and tested in the laboratory. Experimental results verified the design procedure presented.
230 citations
TL;DR: In this article, a non-isolated multi-input multi-output dc-dc boost converter is proposed for hybridizing alternative energy sources in electric vehicles, where the loads power can be flexibly distributed between input sources and charging or discharging of energy storages by other input sources can be controlled properly.
Abstract: A new nonisolated multiinput multioutput dc-dc boost converter is proposed in this paper. This converter is applicable in hybridizing alternative energy sources in electric vehicles. In fact, by hybridization of energy sources, advantages of different sources are achievable. In this converter, the loads power can be flexibly distributed between input sources. Also, charging or discharging of energy storages by other input sources can be controlled properly. The proposed converter has several outputs with different voltage levels which makes it suitable for interfacing to multilevel inverters. Using of a multilevel inverter leads to reduction of voltage harmonics which, consequently, reduces torque ripple of electric motor in electric vehicles. Also, electric vehicles which using dc motor have at least two different dc voltage levels, one for ventilation system and cabin lightening and other for supplying electric motor. The proposed converter has just one inductor. Depending on charging and discharging states of the energy storage system (ESS), two different power operation modes are defined for the converter. In order to design the converter control system, small-signal model for each operation mode is extracted. The validity of the proposed converter and its control performance are verified by simulation and experimental results for different operation conditions.
227 citations
TL;DR: In this paper, the performance of a maximum power point tracking system which implements Incremental Conductance (IC) method was explored. And the system performance of IC algorithm was compared to widely used algorithm - Perturb and Observe (P&O) on a Simulink environment.
194 citations
TL;DR: In this paper, an open-circuit voltage measure is performed during the pseudonormal operation of the interfacing power electronic converter. And the proposed MPPT technique is supported by theoretical analysis and used to control a synchronous Buck-Boost converter.
Abstract: Thermoelectric generators (TEGs) convert heat energy into electricity in a quantity dependent on the temperature difference across them and the electrical load applied. It is critical to track the optimum electrical operating point through the use of power electronic converters controlled by a maximum power point tracking (MPPT) algorithm. The MPPT method based on the open-circuit voltage is arguably the most suitable for the linear electrical characteristic of TEGs. This paper presents an innovative way to perform the open-circuit voltage measure during the pseudonormal operation of the interfacing power electronic converter. The proposed MPPT technique is supported by theoretical analysis and used to control a synchronous Buck-Boost converter. The prototype MPPT converter is controlled by an inexpensive microcontroller, and a lead-acid battery is used to accumulate the harvested energy. Experimental results using commercial TEG devices prove that the converter accurately tracks the maximum power point during thermal transients. Precise measurements in the steady state show that the converter finds the maximum power point with a tracking efficiency of 99.85%.
175 citations
TL;DR: Considering the worst stability problem that often occurs at the system whose source converter is an LC filter, two cascaded systems consisting of a source converter with an LC input filter and a load converter, which is either a buck converter or a boost converter are fabricated and tested to validate the effectiveness of the proposed control methods.
Abstract: Interactions between individually designed power subsystems in a cascaded system may cause instability. This paper proposes an approach, which connects a virtual impedance in parallel or series with the input impedance of the load converter so that the magnitude or phase of the load converter's input impedance is modified in a small range of frequency, to solve the instability problem of a cascaded system. The requirements on the parallel virtual impedance (PVI) and series virtual impedance (SVI) are derived, and the control strategies to implement the PVI and SVI are proposed. The comparison and general design procedure of the PVI and SVI control strategies are also discussed. Finally, considering the worst stability problem that often occurs at the system whose source converter is an $LC$ filter, two cascaded systems consisting of a source converter with an $LC$ input filter and a load converter, which is either a buck converter or a boost converter, are fabricated and tested to validate the effectiveness of the proposed control methods.
148 citations
TL;DR: The proposed test-bed system is composed of a grid-interactive ac-dc converter for regulating the dc-bus voltage, a bidirectional converter for the battery power interface, a renewable energy simulator, dc home appliances modified from conventional ac components, a dc distribution panel board, and its monitoring system.
Abstract: This paper proposes an effective test bed for a 380-V dc distribution system using isolated power converters. The proposed test-bed system is composed of a grid-interactive ac–dc converter for regulating the dc-bus voltage, a bidirectional converter for the battery power interface, a renewable energy simulator, dc home appliances modified from conventional ac components, a dc distribution panel board, and its monitoring system. This paper discusses three isolated power converters, i.e., a bidirectional ac–dc converter, a bidirectional dc–dc converter, and a unidirectional dc–dc converter for the effective power interface of a dc bus. These isolated power converters are designed using a dual-active-bridge converter and the resonant topologies of $CLLC$ and $LLC$ . The proposed test-bed system was implemented using a 5-kW bidirectional ac–dc prototype converter, a 3-kW bidirectional dc–dc prototype converter, and a 3-kW unidirectional dc–dc prototype converter. Finally, the performance of the test-bed system has been verified using practical experiments of load variations and bidirectional power flow, employing the prototype converters.
139 citations
TL;DR: In this article, the authors proposed a multicell switched inductor/ switched-capacitor combined active network converters (MSL/SC-ANC) which combines the advantages of SL/SC unit and active network structure.
Abstract: High step-up voltage gain dc/dc converters are widely used in renewable energy power generation, uninterruptible power system, etc. In order to avoid the influence of leakage inductor in coupled inductors based converters, switched-inductor boost converter (SL-boost), switched-capacitor boost converter (SC-boost) and active-network converter (ANC) have been developed. With the transition in series and parallel connection of the inductors and capacitors, high step-up voltage conversion ratio can be achieved. This paper discusses the characteristics of the switched inductor and switched-capacitor cell; makes some comparisons between the ANC and boost converter. Based on the aforementioned analysis, this paper proposed the multicell switched-inductor/ switched-capacitor combined active network converters (MSL/SC-ANC). The proposed converters combine the advantages of SL/SC unit and active-network structure. Compared with previous high step-up converters, the novel converter provides a higher voltage conversion ratio with a lower voltage/current stress on the power devices, moreover, the structure of proposed SL/SC-ANC is very flexible, which means the quantity of SL and SC cells can be adjusted according to required voltage gain. A 20 times gain prototype is designed as an example to show the design procedure. Theoretical analysis and experimental results are presented to demonstrate the feature of the proposed converter.
128 citations
TL;DR: A family of single-input-multiple-output (SIMO) dc-dc converter topologies, which can provide one step-up and multiple step-down outputs, which has been presented and results show that the proposed converter has very good cross-regulation to step load change as well as dynamic reference change in either output.
Abstract: This paper presents a family of single-input–multiple-output (SIMO) dc–dc converter topologies, which can provide one step-up and multiple step-down outputs. These topologies are synthesized by replacing the control switch of a boost converter topology with series-connected switches and using the additional switch nodes to generate step-down dc outputs. Compared with separate converters, these topologies utilize a lower number of switches and are more reliable due to their inherent shoot-through protection. Analysis shows that the topologies exhibit similar dynamic behavior as individual buck and boost converters. Hence, the control system methodology is the same as that of separate converters, with each output being precisely regulated. The behavior of these converters has been illustrated in this paper using the integrated dual-output converter (IDOC), which has a step-up and a step-down output. The steady-state characteristics and dynamic behavior of the converter have been studied. An analog closed-loop control system for the converter has been described for regulation of both the outputs. The operating principles have been experimentally validated using a 120-W prototype. Results show that the proposed converter has very good cross-regulation to step load change as well as dynamic reference change in either output. The measured efficiencies of the IDOC prototype are around 90%.
127 citations
TL;DR: In this article, a secondary-side phase-shift-controlled (SS-PSC) LLC resonant converter is proposed for applications requiring hold-up time operation, such as distributed power systems and server power supplies.
Abstract: A novel secondary-side phase-shift-controlled (SS-PSC) LLC resonant converter is proposed for applications requiring hold-up time operation, such as distributed power systems and server power supplies. High efficiency at the normal input voltage is achieved because the proposed SS-PSC LLC converter always operates at the series-resonant frequency of the resonant tank. The magnetizing inductor of the proposed converter does not need to be reduced to provide desired voltage boost ratio for the hold-up time operation, which results in reduced conduction losses and improved efficiency. Sufficient voltage boost ratio for the hold-up time operation is provided by using SS-PSC strategy. In comparison with the conventional variable-frequency-controlled (VFC) LLC resonant converter, the main advantages are that the circulating current caused by the magnetizing inductor is effectively suppressed and the efficiency of normal operation is significantly improved. The operation principles, output characteristics, and design considerations of the proposed converter are presented in detail. Experimental results are given to verify the effectiveness and the advantages of the proposed solutions.
121 citations
TL;DR: A modular multilevel dc-dc converter based on the standard boost converter topology but with the normal single switches replaced by a number of capacitor-clamped submodules that exhibits scalability without using a transformer and is capable of bidirectional power flow.
Abstract: High step-up ratio dc–dc converters with megawatt ratings are of interest in wind turbine interfaces and high-voltage direct-current systems. This paper presents a modular multilevel dc–dc converter based on the standard boost converter topology but with the normal single switches replaced by a number of capacitor-clamped submodules. The converter is operated in resonant mode with resonance between submodule capacitors and the arm inductor. A phase-shifted switching arrangement is applied such that there is a constant number, i.e., $N$ , of submodules supporting the high voltage at a time. In this operation mode, the step-up ratio is dependent on the number of submodules and the inductor charging ratio. The converter exhibits scalability without using a transformer and is capable of bidirectional power flow. An application example of a wind turbine interface with a 10 : 1 conversion ratio is demonstrated in simulation. The experimental verification of the concept using a lab-scale prototype is provided.
119 citations
TL;DR: The proposed interleaved buck converter has a lower voltage stress in comparison to the conventional IBC and can also provide a high step-down ratio, which makes it a proper choice for high-power applications where a nonisolated step- down converter with low output current ripple and continuous input current is required.
Abstract: This paper proposes an interleaved buck converter (IBC) with continuous input current, extremely low output current ripple, low switching losses, and improved step-down conversion ratio Unlike the conventional IBC, the proposed converter has a continuous input current, and its output current ripple is extremely low The proposed converter has a lower voltage stress in comparison to the conventional IBC and can also provide a high step-down ratio, which makes it a proper choice for high-power applications where a nonisolated step-down converter with low output current ripple and continuous input current is required Also, the proposed converter can provide current sharing between two interleaved modules without using additional current-sharing control method All of these benefits are obtained without any additional stress on the circuit components A prototype converter with 200-V input and 24-V–10-A output is implemented to verify the theoretical analysis Operational principles and experimental results are presented in this paper
TL;DR: In this article, a model predictive control (MPC) strategy for a nested neutral point-clamped (NNPC) converter is proposed to control output currents and voltages of flying capacitors.
Abstract: This paper proposes a model predictive control (MPC) strategy for a nested neutral point-clamped (NNPC) converter to control output currents and voltages of flying capacitors. The NNPC converter is a four-level converter topology for medium-voltage applications with interesting properties such as operating over a wide range of voltages (2.4–7.2 KV) without the need for connecting power semiconductor in series, high quality output voltage, less number of components compared to other classical four-level topologies. A discrete-time model of the converter is presented and all the control objectives are formulated in terms of the switching states. During each sampling interval, the predicted variables are assessed by the cost function and the best switching state which gives minimum value for the cost function is selected and applied to the converter gating terminals. The performances of the NNPC converter and predictive control scheme are verified through MATLAB/Simulink simulations and their feasibility is evaluated experimentally.
TL;DR: The analysis indicates that, compared to the traditional common dc-bus-based solution, bulky dc-link capacitor is eliminated and single-stage conversion between any two of the three dc-buses are achieved with the TP-B 3 converter, which is beneficial for higher efficiency, power density, and reliability.
Abstract: A systematic method for derivation of a multiport converter (MPC) based on the dc-link inductor (DLI) concept is proposed in this paper. The MPC is generated by interconnecting multiple pulsating voltage cells (PVCs) through the DLIs. The PVCs can be input type, output type, and bidirectional type, and bidirectional MPC topologies can be harvested if all the PVCs are bidirectional type. As a result, a family of novel MPCs, including multiinput converters, multioutput converters, and bidirectional MPCs, are derived. With the proposed MPCs, step-up and step-down voltage conversion between any two of the ports can be implemented. As an example, the three-port bidirectional buck-boost (TP-B 3
) converter is analyzed and applied to a stand-alone renewable power system for interconnection of three dc subsystems. The operation principles, pulse width modulation, and feed-back control strategies are presented and analyzed in depth. The analysis indicates that, compared to the traditional common dc-bus-based solution, bulky dc-link capacitor is eliminated and single-stage conversion between any two of the three dc-buses are achieved with the TP-B 3
converter, which is beneficial for higher efficiency, power density, and reliability. Experimental results are given to verify the feasibility and effectiveness of the developed TP-B 3
converter.
TL;DR: In this paper, a step-up converter with very high voltage gain is proposed, which is based on a natural combination of the switched-coupled-inductor boost converter and the diode-capacitor multiplier.
Abstract: In this study a new scheme of a step-up converter with very high voltage gain is proposed. The scheme is based on a natural combination of the switched-coupled-inductor boost converter and the diode-capacitor multiplier. The study proposes a special scheme of their mutual use for attaining very high voltage gain. An important advantage of the proposed circuit is the avoidance of the current spikes through the transistor and diodes because of the leakage inductance of the coupled inductors. The scheme provides soft commutation of the switch and the diodes. The study analyses the modes of operation and obtains the basic fundamental relations in steady state; an expression for voltage stress across the switch is derived. A new method for dynamic analysis is proposed. The corresponding analytical expressions and curves of the transient behaviour are also obtained. Modelling of the proposed structure and the experimental results are in full agreement regarding the expected efficiency and correctness of the theoretical analysis. A 100 W laboratory prototype was built and verified.
TL;DR: A new family of high efficiency dc/ac grid-tied inverter with a wide variation of input dc voltage with a “boost in boost, buck in buck” inverter, meaning that only one power stage works at high frequency in order to achieve minimum switching loss.
Abstract: This paper presents a new family of high efficiency dc/ac grid-tied inverter with a wide variation of input dc voltage. It is a “boost in boost, buck in buck” inverter, meaning that only one power stage works at high frequency in order to achieve minimum switching loss. The minimum voltage drop of the filtering inductor in the power loop is achieved to reduce the conduction power loss in both “boost” and “buck” mode. The principle of operation is demonstrated through the analysis on the equivalent circuits of a “half-bridge” single-phase inverter. The theoretical analysis shows that when input dc voltage is larger than the magnitude of the ac voltage, it is a voltage-source inverter, and on the contrary it is current-source inverter in the other mode. A 220 V/50 Hz/ 2000 W prototype has been constructed. Simulations and experiments show that it has a good control and system performance.
TL;DR: In this article, a single-switch voltage equalizer using multistacked buck-boost converters is proposed to settle the partial shading issues in photovoltaic (PV) string comprising multiple modules/substrings.
Abstract: Partial shading on a photovoltaic (PV) string comprising multiple modules/substrings triggers issues such as a significant reduction in power generation and the occurrence of multiple maximum power points (MPPs), including a global and local MPPs, that encumber MPP tracking algorithms. Single-switch voltage equalizers using multistacked buck–boost converters are proposed to settle the partial shading issues. The single-switch topology can considerably simplify the circuitry compared with conventional equalizers requiring multiple switches in proportion to the number of PV modules/substrings. The proposed voltage equalizers can be derived by stacking capacitor–inductor–diode filters on traditional buck–boost converters, such as SEPIC, Zeta, and Cuk converters. The optimum equalization strategy is also proposed and discussed for the equalizers to compensate the partially shaded PV modules efficiently. Operational analysis based on a simplified equivalent circuit is performed for a SEPIC-based topology. Experimental equalization tests using the SEPIC-based voltage equalizer were performed emulating partially shaded conditions for a PV panel comprising of three substrings. Local MPPs were eliminated and extractable maximum powers increased by the equalizer, demonstrating the efficacy of the proposed voltage equalizer.
TL;DR: In this article, a bidirectional PWM converter integrating cell voltage equalizer is proposed, which can be used to manage charging/discharging and ensure years of safe operation in conventional energy storage systems using series-connected energy storage cells.
Abstract: In conventional energy storage systems using series-connected energy storage cells such as lithium-ion battery cells and supercapacitors (SCs), an interface bidirectional converter and cell voltage equalizer are separately required to manage charging/discharging and ensure years of safe operation. In this paper, a bidirectional PWM converter integrating cell voltage equalizer is proposed. This proposed integrated converter can be derived by combining a traditional bidirectional PWM converter and series-resonant voltage multiplier (SRVM) that functionally operates as an equalizer and is driven by asymmetric square wave voltage generated at the switching node of the converter. The converter and equalizer can be integrated into a single unit without increasing the switch count, achieving not only system-level but also circuit-level simplifications. Open-loop control is feasible for the SRVM when operated in discontinuous conduction mode, meaning the proposed integrated converter can operate similarly to conventional bidirectional converters. An experimental charge–discharge cycling test for six SCs connected in series was performed using the proposed integrated converter. The cell voltage imbalance was gradually eliminated by the SRVM while series-connected SCs were cycled by the bidirectional converter. All the cell voltages were eventually unified, demonstrating the integrated functions of the proposed converter.
03 Jun 2015
TL;DR: Experimental testing has proven the validity of the proposed network and its application as a high boost dc-dc converter.
Abstract: In this letter, a new topology called “quasi-Y-source dc–dc converter” is presented. It inherits all the advantages of the original Y-source converter. In addition, the new topology draws a continuous current from the source, which is definitely more appropriate for most renewable sources. It also has dc-current-blocking capacitors, which will definitely help to prevent the coupled inductor core from saturation. Experimental testing has proven the validity of the proposed network and its application as a high boost dc–dc converter.
TL;DR: A single-switch nonisolated dc/dc converter for a stand-alone photovoltaic (PV)-battery-powered pump system is proposed in this paper and confirmed the performance of the proposed converter when used in a PV-battery pump system.
Abstract: A single-switch nonisolated dc/dc converter for a stand-alone photovoltaic (PV)-battery-powered pump system is proposed in this paper. The converter is formed by combining a buck converter with a buck-boost converter. This integration also resulted in reduced repeated power processing, hence improving the conversion efficiency. With only a single transistor, the converter is able to perform three tasks simultaneously, namely, maximum-power-point tracking (MPPT), battery charging, and driving the pump at constant flow rate. To achieve these control objectives, the two inductors operate in different modes such that variable switching frequency control and duty cycle control can be used to manage MPPT and output voltage regulation, respectively. The battery in the converter provides a more steady dc-link voltage as compared to that of a conventional single-stage converter and hence mitigates the high voltage stress problem. Experimental results of a 14-W laboratory prototype converter with a maximum efficiency of 92% confirmed the performance of the proposed converter when used in a PV-battery pump system.
TL;DR: In this paper, an integrated double boost SEPIC (IDBS) converter is proposed as a high step-up converter, which utilizes a single controlled power switch and two inductors and is able to provide high voltage gain without extreme switch duty-cycle.
TL;DR: In this article, a new photovoltaic array power converter circuit is presented, which is a transformer-less topology with a grounded PV array and only film capacitors.
Abstract: A new photovoltaic (PV) array power converter circuit is presented. This inverter is a transformer-less topology with grounded PV array and only film capacitors. The motivations are to reduce circuit complexity, eliminate leakage ground currents, and improve reliability. The use of silicon carbide (SiC) transistors is the key enabling technology for this particular circuit to attain reasonable (>97%) efficiency. Some background about the challenges of ground currents and power decoupling to be addressed is first discussed. The proposed solution of a bidirectional buck boost converter, dynamically varying dc link, and half-bridge inverters is then presented along with details on the basic functionality. Some aspects of selecting passive components for the circuit are discussed. The average dynamic model and control system are then presented. Finally, simulation and experiment results are shown demonstrating that the proposed topology is a viable solution.
TL;DR: A single-inductor dual-output (SIDO) buck-boost power factor correction (PFC) converter operating in critical conduction mode and benefits from significant overall cost saving, small size, and light weight.
Abstract: A single-inductor dual-output (SIDO) buck–boost power factor correction (PFC) converter operating in critical conduction mode is proposed in this paper. By multiplexing a single inductor, each output of the SIDO buck–boost converter can be regulated independently. Compared with a conventional two-stage multiple-output converter, the SIDO buck–boost PFC converter benefits from significant overall cost saving, small size, and light weight. Moreover, the efficiency of the SIDO buck–boost PFC converter can be improved due to single-stage power conversion. The control strategy and characteristics of the proposed converter are analyzed. The efficiency, power factor, total harmonic distortion, and output accuracy are verified using the experimental results.
TL;DR: This paper proposes a bidirectional high-efficiency converter with lower number of components created by merging a switched-capacitor converter and a conventionalbidirectional converter, resulting in a hybrid topology.
Abstract: Automotive embedded electronic systems have been increasing in power and complexity and, therefore, more advanced power electronic converters are necessary in these vehicles. Several dual-voltage (42 V/14 V) bidirectional converter architectures have been proposed for automotive systems in recent years. However, most of them have low efficiency or are based in series and parallel configurations with large number of semiconductors and magnetics devices. Therefore, in this paper, we propose a bidirectional high-efficiency converter with lower number of components. This converter was created by merging a switched-capacitor converter and a conventional bidirectional converter, resulting in a hybrid topology. The voltage across the semiconductors of the proposed converter is equal to half of the highest voltage source value. Furthermore, the topology is composed of only one inductor to control the power flow between the two voltage sources. To verify all the mentioned features, a prototype was implemented experimentally, reaching a maximum efficiency of 97.5%.
TL;DR: In this paper, an ultra-high step-down converter is presented, which combines one coupled inductor and one energy-transferring capacitor, and the corresponding voltage conversion ratio is much lower than that of the traditional synchronously rectified (SR) buck converter.
Abstract: In this paper, an ultrahigh step-down converter is presented, which combines one coupled inductor and one energy-transferring capacitor. The corresponding voltage conversion ratio is much lower than that of the traditional synchronously rectified (SR) buck converter, and the proposed converter can achieve extremely low output voltage with an appropriate duty ratio. Moreover, there are three major merits in the proposed converter. One merit is that the voltage conversion ratio of the proposed converter is linear, thereby making control quite easy. Another merit is that if one of the switches fails or is abnormally controlled, a high voltage does not appear in the output terminal, so the output load can be protected. The other merit is that the proposed converter can be driven using the existing SR buck pulse-width modulation control integrated circuit. In this study, brief theoretical deductions and some experimental results are given to verify the feasibility and effectiveness of the proposed converter.
TL;DR: A novel high-gain quadratic boost converter with a voltage multiplier circuit is presented to give an alternative power electronic circuit for high-voltage conversion and low-to-medium power applications.
Abstract: In this study, a novel high-gain quadratic boost converter with a voltage multiplier circuit is presented to give an alternative power electronic circuit for high-voltage conversion and low-to-medium power applications. The proposed converter combines the traditional quadratic boost converter and a coupled-inductor-based voltage multiplier circuit. Compared with the traditional quadratic boost converter, the proposed converter can obtain a much higher output voltage under the same duty cycle and input voltage, and can also reduce the voltage stresses in the power devices. Moreover, the serious input current ripple in the converter with coupled-inductor is reduced. Consequently, the efficiency and the reliability can be improved by using semiconductors with low-voltage level and high performance. The theoretical analysis of the proposed converter is verified by the experimental results.
TL;DR: In this article, a single-stage LED driver based on an interleaved buck-boost circuit and an LLC resonant converter is proposed, which can decrease the system cost and improve the system efficiency.
Abstract: A single-stage LED driver based on an interleaved buck–boost circuit and an LLC resonant converter is proposed. The buck–boost circuit and the LLC resonant converter are integrated by sharing switches, which can decrease the system cost and improve the system efficiency. The input voltage of the buck–boost circuit is half of the rectified voltage, and two buck–boost circuits are formed with the two half-bridge switches and corresponding diodes. The two buck–boost circuits work in interleaved mode and the inductor current is in discontinuous conduction mode, both helping to achieve the power factor (PF) correction. A half-bridge LLC resonant converter is adopted here, and the soft switching characteristic of the LLC resonant converter is not changed by the switch integration. The primary-side switches still work in zero voltage switching (ZVS) mode, and the secondary diodes still work in ZCS mode, which both reduce the switching losses and improve the efficiency of the system. The design process is described in detail this paper, and a 100-W LED street lighting prototype is proposed, with a PF of 0.995, a total harmonic distortion of 5.7%, and an efficiency of 91.6% at full load.
TL;DR: In this article, the authors proposed a resonant converter which is suitable for grid-connected renewable energy sources, and the converter can achieve high voltage gain using an LC parallel resonant tank, which is characterized by zerovoltage-switching (ZVS) turn-on and nearly ZVS turn-off of main switches as well as zero-current switching turnoff of rectifier diodes.
Abstract: With the rapid development of large-scale renewable energy sources and HVDC grid, it is a promising option to connect the renewable energy sources to the HVDC grid with a pure dc system, in which high-power high-voltage step-up dc–dc converters are the key equipment to transmit the electrical energy. This paper proposes a resonant converter which is suitable for grid-connected renewable energy sources. The converter can achieve high voltage gain using an LC parallel resonant tank. It is characterized by zero-voltage-switching (ZVS) turn-on and nearly ZVS turn-off of main switches as well as zero-current-switching turn-off of rectifier diodes; moreover, the equivalent voltage stress of the semiconductor devices is lower than other resonant step-up converters. The operation principle of the converter and its resonant parameter selection is presented in this paper. The operation principle of the proposed converter has been successfully verified by simulation and experimental results.
TL;DR: In this article, a pulse-width modulation modulator for a noninverting bidirectional buck-boost converter is analyzed and a corresponding average-mode current controller design is revealed, where the main feature of the modulator is the ability to create switching sequences for both converter legs without requiring any information regarding either operation mode or the direction of power flow.
Abstract: A pulse-width modulation modulator for a noninverting bidirectional buck-boost converter is analyzed and a corresponding average-mode current controller design is revealed. The main feature of the modulator is the ability to create switching sequences for both converter legs without requiring any information regarding either operation mode or the direction of power flow. The modulator receives a control signal generated by the current controller, and a triangular carrier and generates driving signals with two different duty cycles, allowing tight control of the inductor current throughout the entire operating range. The underlying circuitry is thus relatively simple; moreover, the proposed method greatly simplifies the outer loop controller design. The revealed findings are supported by simulations and experiments.
TL;DR: In this article, a new hysteresis window method is proposed as a solution for avoiding the operational dead zone that exists at the transition between buck and boost operating modes in all noninverting buck-boost converters.
Abstract: A new hysteresis window method is proposed as a solution for avoiding the operational dead zone that exists at the transition between buck and boost operating modes in all noninverting buck–boost converters. In addition, this method also eliminates the discontinuities in the converter's steady-state output voltage transfer characteristic, which is a function of the duty cycle. The converter's output voltage function is surjective and, therefore, smooth mode transitions are achieved. The negative effects of operating within the dead zone are shown by the presence of subharmonics in the output voltage, increased output voltage ripple, poor regulation, and the instability of the converter during the transition between buck and boost operating modes. The dead-zone avoidance technique proposed in this paper eliminates all these issues while at the same time ensures highly efficient operation of the converter. An additional advantage of the technique is its simplicity, which allows for implementation into low-cost digital signal controllers, as well as into analog control circuits. The advantageous features of the proposed approach were evaluated on the basis of comparisons with three other dead-zone avoidance approaches and the initial case, which does not utilize any dead-zone avoidance technique. All the experiments were carried out on a purpose-built prototype of a noninverting buck–boost converter with magnetically coupled inductors.
TL;DR: A nonisolated bidirectional dc-dc converter has been proposed in this brief for charging and discharging the battery bank through a single circuit in applications of uninterruptible power supplies and hybrid electric vehicles.
Abstract: A nonisolated bidirectional dc–dc converter has been proposed in this brief for charging and discharging the battery bank through a single circuit in applications of uninterruptible power supplies and hybrid electric vehicles. The proposed bidirectional converter operates under a zero-voltage switching condition and provides large voltage diversity in both modes of operation. This enables the circuit to step up the low-battery bank voltage to high dc-link voltage, and vice versa. The bidirectional operation of the converter is achieved by employing only three active switches, a coupled inductor, and an additional voltage clamped circuit. A complete description of the operation principle of the circuit is explained, and the design procedure of the converter has been discussed. The experimental results of a 300-W prototype of the proposed converter confirmed the validity of the circuit. The maximum efficiency of 96% is obtained at half load for boost operation mode and 92% for buck mode of operation.