Three-state Switching Cell Research Articles

A Soft Switched High Gain Boost Converter With Coupled Inductor for Photovoltaic Applications

This paper presents a high-gain boost converter (HGBC) with an auxiliary circuit based on a three-state switching cell (TSSC). The auxiliary circuit enables the switches to operate in zero voltage switching (ZVS) and zero current switching (ZCS) conditions. The proposed converter provides a high voltage gain with reduced voltage stress across the switches. Here the converter is integrated with a voltage multiplier circuit (VMC) and coupled inductor (CI), which boosts the converter's voltage, and the output of this converter can be easily connected to a grid-tied inverter for renewable energy applications. The superior performance of the proposed converter with the auxiliary circuit is analyzed and compared with TSSC based HGBC operated at a 100 kHz frequency, and the results obtained are verified with the hardware implementation of a 950 W prototype with 96.5% efficiency.

3SSC-A-Based Step-Down DC–DC Converters: Analysis, Design and Experimental Validation

This paper proposes two non-isolated step-down DC–DC converters based on the type-A three-state switching cell (3SSC-A), resulting in an alternative to the buck and buck-boost classical converters, respectively. The proposed topologies are part of a group of unexplored converters that employ the 3SSC-A, which has the advantages of 3SSC-based converters, such as high power density, reduced current stress on the semiconductors and suitable thermal loss distribution. In this regard, a complete static analysis is performed, including a detailed study of all semiconductor voltage and current efforts and developing loss models for each one. Moreover, by using simulation models, AC sweep analyses validate the dynamic frequency response of each converter’s small-signal models, and PI-based output–voltage closed-loop controllers are duly designed. Finally, the topologies are experimentally validated through the implementation of adequately designed prototypes, achieving efficiency values greater than 91% under several output power rates varying from 50% to 100%.

Predictive Control Applied to a Single-Stage, Single-Phase Bidirectional AC-DC Converter

This work aims to implement the control system of a single-phase, multi-port AC-DC converter with high-frequency isolation based on the dual active bridge (DAB) topology associated with the three-state switching cell (3SSC) applied to a distributed generation system. The converter has one ac port and two dc ports, this being a multi-input, multi-output (MIMO) system in which there is a coupling between the input and output variables. The generalized predictive control (GPC) is chosen to regulate the dc-link voltages. GPC is a well-consolidated approach in the literature, which can deal with MIMO coupled systems while presenting friendly-tuning rules. The current loop employs a traditional proportional plus resonant (P+R) controller because it has a single-input, single output (SISO) characteristic, as advanced controllers are unnecessary. Experiments are performed on a 1-kW prototype to validate the performance of the developed controller and show its advantages compared with traditional control strategies.

DC-DC 3SSC-A-Based Boost Converter: Analysis, Design, and Experimental Validation

A detailed analysis and validation of the DC-DC boost converter based on the three-state switching cell (3SSC) type-A are presented in this paper. The study of this topology is justified by the small amount of research that employs 3SSC-A and the advantages inherent to 3SSC-based converters, such as the division of current stresses between the semiconductors, the distribution of thermal losses, and the high-density power. Therefore, a complete static analysis of the converter is described, as well as the study of all voltage and current stresses in the semiconductors, the development of a loss model in all components, and a comparison with other step-up structures. Additionally, the small-signal model validation is accomplished by comparing the theoretical frequency response and the simulated AC sweep analysis. Finally, implementing a simple controller structure, the converter is experimentally validated through a 600 W prototype, where its overall efficiency is examined for various load conditions, reaching 96.8% at nominal load.

Three-state switching cell boost converter using H-inf controller

Abstract This paper presents the modeling and control of a non-minimum phase dc-dc boost converter based on the three - state switching cells. In any double stage grid-connected system the converter forms an interface between the photovoltaic source and the inverter. As the control and regulation of the converter output is a vital part of penetration of renewable to grid, therefore, this paper had attempted the control of a converter topology that can reduce the current stress across its switches. But the system becomes highly unstable and complex which has been validated by predicting the limit cycle with a describing function. The Controller design is implemented after reducing the complexity of the system using the Model order reduction principle. H-inf controller being robust in nature is applied for stable and regulated output.

Output Feedback Robust Control with Anti-Windup Applied to the 3SSC Boost Converter

This paper deals with the problem of synthesizing an anti-windup compensator with the robust output feedback model predictive control (MPC) for uncertain systems using linear matrix inequalities (LMI) by incorporating Lyapunov functions. The proposed control is applied in the polytope modeling of three-state switching cell (3SSC) DC-DC converter. The approach involves an off-line design of a robust state observer. And the results shown in this study prove the effectiveness of the proposal MPC with anti-windup and the conditions guarantee the stability of the closed-loop system.

Robust control with an anti-windup technique based in relaxed LMI conditions for LTV system

This paper proposes a new technique to address the anti-windup (AW) with model predictive control (MPC) scheme for linear time-varying (LTV) systems. The main advantage of this new approach is the reduced conservativeness compared with other well-known anti-windup techniques and to prevent integration windup in MPC controllers when the actuators are saturated. The control with AW is applied in a three-state switching cell (3SSC) DC-DC converter operating under saturation conditions. The MPC with proposed anti-windup is compared with the MPC technique and with MPC-AW without relaxation. The MPC-AW with relaxation improves the performance when the converter operated in the saturated mode and allows the rational use of the converter. The simulation results validated the efficiency of the proposed approach and showed that the proposed approach not only allows working better with the polytope modeling but also improves the response under LTV disturbance.

Survey on topologies based on the three‐state and multi‐state switching cells

The introduction of the three-state switching cell (3SSC) and the multi-state switching cell (MSSC) has led to the proposal of several converter topologies, where prominent characteristics regarding reduced dimensions of filter elements, high efficiency, and increase of maximum power levels are achieved. Even though the active switches associated to the 3SSC and MSSC are driven by signals obtained from multiple phase-shifted carriers similarly to the interleaving technique, there are significant differences between the aforementioned approaches. Within this context, this work intends to analyse several converter topologies employing the 3SSC and MSSC that were previously reported in the literature. An overview of important concepts regarding interleaved and 3SSC-based converters is initially presented, as potential advantages and drawbacks are discussed in detail. Besides, it is also shown how the 3SSC and MSSC can be employed in the conception of power converter topologies for distinct applications, e.g. high-voltage step-up non-isolated dc-dc converters, power factor correction rectifiers, and multilevel inverters.

Development of A Small-Signal Model for The DC-DC Buck Converter Based on The Three-State Switching Cell

This paper presents the small-signal modeling of a dc-dc buck converter based on the three-state switching cell (3SSC) using the PWM (pulse width modulation) switch model, which is a far simple approach if compared with other similar techniques e.g. average state-space modeling. The ac model is properly derived, which allows obtaining relevant transfer functions involving several variables. It is also shown that the Bode diagrams corresponding to the mathematical expressions obtained in the theoretical analysis are properly verified by simulation, being able to represent both operating conditions of the 3SSC i.e. nonoverlapping mode and overlapping mode. Finally, some results regarding the converter operation in voltage mode control are presented and discussed.

Unified Second-Stage LC Filter Applied in the Three-State Switching Cell Buck–Boost Converter: Static and Dynamic Analysis and Experimentation

This paper presents a unified second-stage LC filter applied in the three-state switching cell buck-boost converter, which provides current and voltage with low ripple and low noise. The unified second-stage filter promotes a reduction in the number of devices while maintaining the filtering performance of the converter, with second-stage LC filters at the input and at the output. Moreover, the unified filter, when associated with a three-state switching cell buck- boost converter, allows a size reduction of filter devices, especially for designs with duty cycle range around 1/2. Furthermore, the unified filter arrangement provides nondissipative clamping of switching devices and reduce the system order when compared to the converter with second-stage LC filters. In this paper, the static and dynamic characteristics of the proposed converter in continuous conduction mode (CCM) are reported. Experimental data were obtained from a laboratory prototype with an input range of 32~72 V, constant output of 48 V, a load of 150 W, and switching frequency of 45 kHz. The measured efficiency for the rated load was 97% for maximum input voltage. A comparison of the size and performance of the proposed filter with the topology that uses second-stage LCfilters at the input and at the output is also presented.

Three‐state switching cell (3SSC)‐based non‐isolated dc–dc boost‐type converter with balanced output voltage and wide voltage conversion range

This work presents a non-isolated step-up dc–dc converter with wide voltage conversion range based on the three-state switching cell, which is suitable for distinct applications, e.g. renewable energy and uninterruptible power supply (UPS) systems. Prominent advantages can be addressed to the topology, i.e. continuous input current, thus making it a proper choice for the use of battery banks as the input voltage source; the ability to operate at high power, high-current levels while maintaining current sharing through the main switches without the need of special control schemes; reduction of size, weight, and volume of filter elements, which are designed for twice the switching frequency; the maximum voltage across the controlled switches is half of the total output voltage; naturally balanced voltages across the dc-link capacitors exist; and the voltages across the switches are naturally clamped to that across the output filter capacitor, avoiding the need for external snubbers. The complete qualitative analysis of the converter is presented, including the operating principle and a step-by-step design procedure. A transformerless online UPS topology is also briefly described as a potential application for the introduced converter. Finally, experimental waveforms obtained from a 1.55-kW prototype are shown and relevant issues are discussed.

A unified modeling approach for DC-DC converters based on the three-state switching cell

This paper proposes a general small-signal model for the representation of dc-dc converters based on the three-state switching cell (3SSC) operating in continuous conduction mode (CCM). Even though such power electronic converters present distinct behaviors depending on the duty cycle range i.e. 0 < D < 0.5 and 0.5 < D < 1, the developed analysis effectively shows that the derived model is valid in either case. An approach similar to the PWM (pulse width modulation) switch is employed, being this a fair, simple, and straightforward technique if compared with other similar ones e.g. average state-space modeling. Dc and ac small-signal models can then be obtained in order to provide relevant expressions associated to the converters e.g. the static gain and several transfer functions used in the implementation of closed-loop control. A dc-dc buck converter is also investigated, whose model is properly represented by mathematical expressions that are validated by simulation tests for both operating conditions of the 3SSC.

High Step-Up DC/DC Converter with Three-State Switching Cell

本文提出一种基于耦合电感和三态开关单元有机结合思想的DC/DC变换器，采用两个耦合电感的一次绕组分别替代传统交错并联DC/DC变换器的两个分立电感，将耦合电感的二次绕组及其融合二极管和电容构成两个独立的倍压单元，实现了高电压增益，同时输入端采用交错并联，不仅减少开关管的电流应力，而且减小输入电流纹波。对其工作原理和性能特点分别进行了分析，结果表明该变换器具有输出电压高增益、低电压应力、低输入电流纹波。 A novel DC/DC converter was proposed based on the combination of coupled inductors and three- state switching cell. The primary windings of the two coupled inductors are respectively replaced by two separate inductors of traditional interleaved DC/DC converter; the two voltage multiplier modules are composed of the secondary line windings of coupled inductors and diodes and capacitance to achieve a considerably higher voltage gain. The two-phase interleaved configuration not only reduces the current stress through each power switch, but also constrains the input current ripple. The operation principle and property of the converter are analyzed in detail. The results show that the proposed converter has the characteristics of high conversion ratio, low voltage stress and low current ripple.

Novel bidirectional DC–DC converters based on the three-state switching cell

ABSTRACTIt is well known that there is an increasing demand for bidirectional DC–DC converters for applications that range from renewable energy sources to electric vehicles. Within this context, this work proposes novel DC–DC converter topologies that use the three-state switching cell (3SSC), whose well-known advantages over conventional existing structures are ability to operate at high current levels, while current sharing is maintained by a high frequency transformer; reduction of cost and dimensions of magnetics; improved distribution of losses, with consequent increase of global efficiency and reduction of cost associated to the need of semiconductors with lower current ratings. Three distinct topologies can be derived from the 3SSC: one DC–DC converter with reversible current characteristic able to operate in the first and second quadrants; one DC–DC converter with reversible voltage characteristic able to operate in the first and third quadrants and one DC–DC converter with reversible current and voltage characteristics able to operate in four quadrants. Only the topology with bidirectional current characteristic is analysed in detail in terms of the operating stages in both nonoverlapping and overlapping modes, while the design procedure of the power stage elements is obtained. In order to validate the theoretical assumptions, an experimental prototype is also implemented, so that relevant issues can be properly discussed.

A Nonisolated DC–DC Boost Converter With High Voltage Gain and Balanced Output Voltage

This paper presents a dc-dc boost converter with high voltage gain based on the three-state switching cell for split-capacitor neutral-point-clamped inverters. The proposed converter is analyzed considering the operation in continuous conduction mode and duty cycle higher than 0.5, which corresponds to overlapping mode. The main characteristics of the topology are operation at high switching frequency, whereas the input inductor is designed for twice such frequency; in order to minimize weight and volume, the voltage stress across the switches is lower than half of the output voltage and naturally clamped by one output capacitor, allowing the use of MOSFET transistors with reduced intrinsic on-resistance; the input current presents small ripple; the output voltage can be further stepped up by increasing the transformer turns ratio without compromising the voltage stress across the switches; and the output voltage is naturally balanced, thus making the converter suitable for supplying split-capacitor inverters. Several topologies where a high voltage step-up is possible are initially investigated in the literature. Then, the principle of operation and experimental results for a 1-kW prototype are presented to validate the theoretical analysis and demonstrate the converter performance.

DC–DC Nonisolated Boost Converter Based on the Three-State Switching Cell and Voltage Multiplier Cells

This work introduces a dc-dc boost converter based on the three-state switching cell and voltage multiplier cells. A brief literature review is presented to demonstrate some advantages and inherent limitations of several topologies that are typically used in voltage step-up applications. The behavior of the converter is analyzed through an extensive theoretical analysis, while its performance is investigated by experimental results obtained from a 1-kW laboratory prototype, as relevant issues are discussed. The converter can be applied to uninterruptible power supplies and is also adequate to operate as a high gain boost stage cascaded with inverters in renewable energy systems. Furthermore, it can be applied to systems that demand dc voltage step up such as electrical fork-lift, renewable energy conversion systems, and many other applications.

Modelling of nonisolated high-voltage gain boost converters using the PWM switch model

This paper presents the small-signal models for nonisolated dc–dc boost converters based on the three-state switching cell (3SSC) and voltage multiplier cells (VMCs) by using the concept of pulse-width modulation switch introduced by Vorpérian. Two possible topologies are analysed in the study using one multiplier cell (VMC = 1) and two multiplier cells (VMC = 2). The models are validated by properly comparing the theoretical curves with those obtained in simulation tests. Besides, conventional average current-mode control is implemented in practice for the topology with VMC = 2. An experimental prototype rated at 1 kW is evaluated so that it can be seen that the control system is stable and the dynamic response of the converter is satisfactory.

Comparative analysis between overlapping and non-overlapping operation modes for the PWM buck converter using the three-state switching cell

This article presents a comparative study involving a buck converter derived from the three-state switching cell in both operation modes, i.e. non-overlapping and overlapping modes, since it is well known in literature that several advantages can be addressed to topologies based on this approach. In the case of the mentioned converter, only part of the load delivered to the load flows through the controlled switches, so that operation at high-current high-power levels is possible. Besides, the design of reactive elements such as very autotransformer and filter inductor is performed for twice the switching frequency, with consequent reduction of size, weight and volume. Another clear advantage is that the area for which the converter operates in continuous conduction mode is wider than that for the discontinuous conduction mode in comparison with the so-called classical non-isolated buck converter. The operation of the converter, which was previously proposed in literature, is analysed considering the aforementioned modes in terms of the efficiency, and similar approaches for the non-isolated dc–dc conversion are also investigated.

Analysis, Design, And Experimentation of a Buck Converter Based on the Three-state Switching Cell Operating in Overlapping Mode

&#x0D; This work presents the detailed analysis of the dc-dc nonisolated buck converter based on the three-state switching cell operating in overlapping mode, which occurs when the duty cycle of the active switches is higher than 0.5. Only part of the load power is processed by the active switches due to the use of the autotransformer, thus reducing the peak current through the switches to half of the load current, as higher power levels can then be achieved by the proposed topology. The volume of reactive elements i.e. inductors and capacitors is also decreased since the ripple frequency of the output voltage is twice the switching frequency. Due to the intrinsic characteristics of the topology, total losses are distributed among all semiconductors. Another advantage of this converter is the reduced region for discontinuous conduction mode when compared to the conventional buck converter as demonstrated by the static gain plot. Besides, the input current is continuous and the ripple current is reduced, what is not verified in the classical buck converter. The theoretical approach is detailed through qualitative and quantitative analyses, design procedure, and a comparison with similar topologies. Finally, an experimental prototype rated at 1 kW is implemented, while the main experimental results are presented and adequately discussed to clearly identify its claimed advantages.&#x0D;

A DC–DC Converter Based on the Three-State Switching Cell for High Current and Voltage Step-Down Applications

This paper presents a pulsewidth modulation dc-dc nonisolated buck converter using the three-state switching cell, constituted by two active switches, two diodes, and two coupled inductors. Only part of the load power is processed by the active switches, reducing the peak current through the switches to half of the load current, as higher power levels can then be achieved by the proposed topology. The volume of reactive elements, i.e., inductors and capacitors, is also decreased since the ripple frequency of the output voltage is twice the switching frequency. Due to the intrinsic characteristics of the topology, total losses are distributed among all semiconductors. Another advantage of this converter is the reduced region for discontinuous conduction mode when compared to the conventional buck converter or, in other words, the operation range in continuous conduction mode is increased, as demonstrated by the static gain plot. The theoretical approach is detailed through qualitative and quantitative analyses by the application of the three-state switching cell to the buck converter operating in nonoverlapping mode (D <; 0.5). Besides, the mathematical analysis and development of an experimental prototype rated at 1 kW are carried out. The main experimental results are presented and adequately discussed to clearly identify its claimed advantages.