Continuous Input Current Waveform Research Articles

High step‐up direct ac‐ac boost converter with optimal component counts based on SEPIC

AbstractThis paper introduces a new direct step‐up ac‐ac converter designed based on the SEPIC. It provides a higher step‐up conversion ratio than other counterparts with valuable features like high efficiency, reasonable input and output total harmonic distortions (THD), continuous input current waveform, common ground, few components, and single‐stage conversion without snubber and LC filters. Unlike most counterparts, the duty cycle can be varied between zero and one in boost operation and is not limited to any value below one. The voltage stress on one switch is reduced by increasing the winding coefficient of the utilized coupled inductor, and current stress on another is independent of this coefficient. It reduces the switches' losses and improves the converter efficiency. Thanks to the above attributes, the proposed converter is suitable for inductive power transfer from low‐voltage ac sources, operating as an ac voltage regulator for sensitive ac loads, and any applications that require a boost converter with few components. This article shows the converter's operation principle and evaluates its performance through experiments on a 225 W prototype. Accordingly, the maximum obtained efficiency is 95.4%. The input and output current THDs for the nominal inductive load equal 4.5 and 2.8%, respectively. Results confirm the claims.

A High Power Density Converter with a Continuous Input Current Waveform for Satellite Power Applications

Conventional Active Clamp-Forward topology is studied for a satellite converter owing to its comparitively simple structure, minimum number of components and fine clamping capability concerning its switch voltage stress. However, it has a high switch voltage stress,a high di/dt level and has pulsating input current shape. These are disadvantageous with respect to the EMI filter size and high input voltage converter applications.To get the better of these drawbacks, a new ACF topology with a continuous input current waveform is proposed . By this proposed waveform ,the voltage stresses on the main switches are relieved. This is crucial reliability of satelite FET switches, by utilizing a two series connected structure. These conditions will allow the proposed converter to serve as a high input voltage, high power density satellite converter.

A High-Power-Density Converter With a Continuous Input Current Waveform for Satellite Power Applications

Satellite dc–dc power converters are required to have electromagnetic interference (EMI) compatibility as well as high reliability. The requirement of high reliability limits the complexity of the structure as well as the number of low-reliability components. In this paper, a conventional active-clamp-forward (ACF) topology is examined for a satellite converter owing to its relatively simple structure, small number of components, and good clamping capability regarding its switch voltage stress. However, it has a pulsating input current shape, a high di / dt level, and high switch voltage stress, which are disadvantageous with regard to the EMI filter size and high-input-voltage converter applications. To overcome these drawbacks, a new ACF topology with a continuous input current waveform is proposed. In the proposed waveform, the voltage stresses on the main switches are relieved, which is crucial to ensure the reliability of satellite FET switches, by utilizing a two-series connected structure. These features allow the proposed converter to serve as a high-input-voltage, high power-density satellite converter. In this paper, 100 W prototype converters with 50 V inputs operating at 300 kHz are built with a high power density of 47.9 W/in3. Experiments on these prototype converters are carried out to verify the features.

Digital Control of a Bidirectional DC/DC Switched Capacitor Converter for Hybrid Electric Vehicle Energy Storage System Applications

This paper presents the analysis and novel controller design for a hybrid switched-capacitor (SC) bidirectional DC/DC converter, applicable for electric and plug-in hybrid electric vehicles (HEV/PHEV) energy storage system (ESS) applications, based on power of traction motor and battery current gradient. Features of voltage step-down, voltage step-up, and bi-directional power flow are integrated into a single circuit. The developed novel control strategy enables simpler dynamics compared to a standard buck converter with input filter. Experimental results show, the proposed converter topology enables good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both buck as well as boost modes of operation.

Prototype Design and Controller Implementation for a Battery-Ultracapacitor Hybrid Electric Vehicle Energy Storage System

This paper presents the modeling, design, and novel control strategy development for a hybrid switched-capacitor bidirectional dc/dc converter, applicable for a hybrid electric vehicle energy storage system. The proposed control strategy is based on the power profile of the traction motor and the gradient of battery current. Features of voltage step-down, voltage step-up, and bidirectional power flow are integrated into a single circuit, and are verified on an experimental prototype. The developed control strategy enables simpler dynamics, compared to a standard buck converter with input filter, good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both buck and boost modes of operation.

Design and control of a Luo converter for variably loaded hybrid electric vehicle energy storage system

This paper presents the analysis and novel hybrid controller design for a 4-quadrant (4-Q) switched-capacitor (SC) Luo bidirectional DC/DC converter, applicable for hybrid electric and plug-in hybrid electric vehicle energy storage system (ESS) applications, based on power of traction motor and battery current gradient. Features of voltage step-down, voltage step-up, and bi-directional power flow are integrated into a single circuit. The novel control strategy enables simpler dynamics compared to a standard buck converter, with input filter, good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both modes of operation (buck and boost modes).

Advanced digital control for a switched capacitor and interleaved switched capacitor hybrid electric vehicle energy management system

This paper presents the analysis and novel controller design for a two-quadrant hybrid switched capacitor (SC) converter and interleaved two-quadrant SC bidirectional DC/DC converter for a hybrid electric vehicle dual energy storage system. The designed novel control strategy enables simpler dynamics compared to a standard buck converter with input filter, good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both buck as well as boost modes of operation.

Modeling, Simulation, and Control of an Advanced Luo Converter for Plug-In Hybrid Electric Vehicle Energy-Storage System

This paper presents the analysis and novel controller design for a hybrid switched-capacitor bidirectional dc/dc converter that is applicable for hybrid electric vehicle (HEV)/plug-in HEV energy-storage system (ESS) applications, based on the power of the traction motor and the gradient of the battery current. Features of voltage step-down, voltage step-up, and bidirectional power flow are integrated into a single circuit. The novel control strategy enables simpler dynamics, compared with a standard buck converter, with input filter, good regulation capability, low electromagnetic interference, lower source current ripple, ease of control, and continuous input current waveform in both modes of operation (buck and boost modes).

A Novel Control Technique for a Switched-Capacitor-Converter-Based Hybrid Electric Vehicle Energy Storage System

This paper presents the analysis and novel controller design for a hybrid switched-capacitor bidirectional dc/dc converter. Features of voltage step-down, step-up, and bidirectional power flow are integrated into a single circuit. The novel control strategy enables simpler dynamics compared to a standard buck converter with an input filter, good regulation capability, low electromagnetic interference, lower source current ripple, ease of control, and continuous input current waveform in both modes of operation (buck and boost modes).

Development of a multistage current-controlled switched-capacitor step-down DC/DC converter with continuous input current

This paper presents the design and analysis of a low-profile multistage current-controlled switched-capacitor (SC) step down DC/DC converter. The converter not only exhibits all advantages of classical SC converters, but also features good regulation capability and continuous input current waveform, resulting in low conducted electromagnetic interference with the supply network. The concept of energy transfer is achieved by paralleling the input and output of two step-down converter cells and operating them in antiphase. The voltage conversion ratio is determined by controlling the charging trajectories of the capacitors in each cell. As it is unnecessary for the circuit to use any inductive elements, possibilities of integrated circuit fabrication and high power density are promising. By applying the state-space averaging technique, a third-order state-space model for an n-stage converter is derived. Static and small-signal dynamic behaviors of the converter are investigated. A 70 W 48 V/12 V converter is implemented. Analytical predictions are verified with experimental measurements.

Development of a switched-capacitor DC-DC converter with bidirectional power flow

This brief presents a switched-capacitor dc-dc converter that offers features of voltage step-down, voltage step-up, and bidirectional power flow. Concept of energy transfer is achieved by using two current-controlled bidirectional converter cells, which operate in antiphase. Good regulation capability and continuous input current waveform are other substantial advantages that facilitate practical realization and reduce electromagnetic interference with other circuits and supply networks. State-space averaging technique is applied to study the static and dynamic characteristics. A 20-W, 5-V-9-V prototype has been built and has an overall efficiency of over 80% in all operations.

Development of a switched-capacitor DC/DC boost converter with continuous input current waveform

A new switched-capacitor (SC)-based dc/dc boost converter is presented. It features good regulation capability and continuous input current, giving lower conducted electromagnetic interference with the supply network than classical SC converters. The converter is realized by using two quasi-switched-capacitor boost converter cells. The dc voltage conversion ratio is controlled by the gate-source voltage of a quasi-switch in each cell, in order to adjust the charging trajectory of the capacitors. By renouncing inductive elements, the converter can be implemented in small size, light weight, high power density, and it is possible to fabricate it in an IC form. A prototype of a 20 W, 6 V/9 V dc/dc boost converter with overall efficiency of 74% and power density of 10 W/in/sup 3/ has been built. The state-space averaging technique is applied to study the static and dynamic behaviors of the converter.

Design and analysis of a switched-capacitor-based step-up DC/DC converter with continuous input current

This paper presents the use of the current control scheme in switched-capacitor (SC)-based step-up dc/dc converter. It not only includes all positive characteristics of previous SC converters, including small size, light weight, high power density, and the amenability to IC hybridization, but also has the prominent features of continuous input current waveform and better regulation capability than the traditional SC converters. The problem of conducted electromagnetic interference with the supply network, which generally exists in previous SC converters, is highly suppressed. The concept of energy transfer is achieved by using dual SC step-up converter cells operating in antiphase. Each cell is switching between two topologies for the same duration. The dc voltage conversion ratio is controlled by the current control scheme in order to adjust the charging profile of the capacitors. A generalized n-stage converter is presented and is analyzed by a simplified third-order state-space equation set. The static and dynamic behaviors and the design constraints of the converter are derived. A prototype of the 30 W 5 V/12 V two-stage converter has been built, giving an overall efficiency of 78% with power density of 15 W/in/sup 3/. Its stability of operation is also presented.