Small-signal Model Of Converter Research Articles

An autonomous solar PV system using boost TPC for energy harvesting with mode-based power flow management control

Energy harvesting from environment provides a compelling alternative to battery-powered standalone systems. The rising use of green energy resources in energy sector has a substantial impact on the low voltage DC (LVDC) systems. Multiport converters make it easier to convert renewable energy for use in everyday situations. To ensure uninterruptible power supply, a non-isolated Three-Port Converter (TPC) acts as a gateway for renewable sources, energy storage, and loads. The paper describes a modified power flow management control for a standalone solar PV system using boost TPC with time sharing control and an added mode-based controller for voltage regulation. To operate the TPC effectively in Dual Output (DO), Dual Input (DI) and Single Input and Single Output (SISO) modes, localized controllers are used. The converter small signal model is developed for all operating modes and based on this, sampled data control theory is applied to design the digital controller for load regulation. When the TPC switches from one operating mode to another, the voltage regulation control sets the controller parameters for the appropriate mode. Also, to extend battery lifespan, the control algorithm includes a battery overcharge prevention mechanism. The proposed algorithm is realized in a System on a Programmable Chip (SoPC) using the Field Programmable Gate Array (FPGA) Cyclone-III and Nios-II as processor. The system is tested in real time with solar PV as the source of energy and a lead-acid battery as the storage.

A Three-Phase Single-Sensor-Based Cuk-Derived PFC Converter With Reduced Number of Components for More Electric Aircraft

A new three-phase Cuk-derived power factor corrected (PFC) converter with only three switches for more electric aircraft is presented. The proposed converter benefits limited components for its operation, and only one semiconductor from each phase is in the current conduction path throughout the converter operation that substantially reduces the conduction losses leading to high efficiency and low converter thermal management. Further, the control effort required for converter operation is very less as all the three switches are driven by one gate signal. The converter output inductors are designed for discontinuous current operation for the entire converter power range to realize natural PFC at ac power source. The converter control is very simple, economical, and reliable since only one sensor is required for implementation. A detailed discussion on the converter steady-state operation for one switching cycle is presented. The converter small-signal model and the design expressions are derived to ease the converter control and the design. Further, the feasibility of the proposed scheme and the design are validated with the experimental results from a 2-kW laboratory prototype.

High-Efficiency Three-Phase Single-Stage Isolated Flyback-Based PFC Converter With a Novel Clamping Circuit

This article analyzes a three-phase single-stage isolated flyback-based power factor correction converter and presents a novel clamping circuit to capture the transformers leakage inductance energy. The converter unity power factor operation is obtained by using the inherent resistance property of discontinuous conduction mode. Thus, the input current shaping circuit is eliminated and resulted in a single-loop control system. Therefore, the converter control circuit requires only one sensor, which decreases the system cost, and also increases the system robustness to high-frequency noise. With the proposed clamping circuit, the transformers leakage inductance energy is successfully captured in clamping capacitor, and thereby, it is fed to the dc load by using an auxiliary two-switch forward converter which enhanced the overall operating efficiency of a converter. The converter detailed steady-state operation and the design considerations are presented. Each power component voltage stress expressions are derived to simplify the converter design, and the converter small-signal model is presented to help the controller design. The novelty and performance of the converter is verified by both simulation and experimentation.

ZVS 위상천이 풀브릿지 컨버터의 디지털 샘플링 기법에 따른 소신호 모델 분석

ZVS 위상천이 풀브릿지 컨버터의 디지털 샘플링 기법에 따른 소신호 모델 분석

Active damping method to reduce the output impedance of the DC–DC converters

In the cascaded power system, instability may occur because of the impedance interaction. The system can be stabilised by passive damping or control methods to reduce the output impedance of the source converter and improve the damping characteristics. This study focuses on the source converter in the cascaded system and presents a new active damping control to reduce the output impedance of the converter by a proper active damping controller. The method to compute the corresponding active damping controller is proposed in this study. By the application of the active damping method, a virtual resistor in parallel with the output of the converter's small signal model can be realised. Therefore the output impedance can be reduced. Because the virtual resistor exists only in the small signal model, the steady-state operating point is not affected and the value of the virtual resistor can be changed. The experiment results of a Buck converter with the active damping controller under different conditions are proposed to verify the effectiveness of the active damping control. Besides, an active damping controller is applied to an unstable cascaded system in simulation to stabilise the cascaded system so the effectiveness of this method is also verified.

Study & Analysis of Dc to Dc Converter Using Simulink

Every Electronic circuit is assumed to operate off some supply voltage which is usually assumed to be constant. A voltage regulator is a power electronic circuit that maintains a constant output voltage irrespective of change in load current or line voltage. Many different types of voltage regulators with a variety of control schemes are used. With the increase in circuit complexity and improved technology a more severe requirement for accurate and fast regulation is desired. This has led to need for newer and more reliable design of dc-dc converters. The dc-dc converter inputs an unregulated dc voltage input and outputs a constant or regulated voltage. The regulators can be mainly classified into linear and switching regulators. All regulators have a power transfer stage and a control circuitry to sense the output voltage and adjust the power transfer stage to maintain the constant output voltage.Since a feedback loop is necessary to maintain regulation, some type of compensation is required to maintain loop stability. Compensation techniques vary for different control schemes and a small signal analysis of system is necessary to design a stable compensation circuit. State space analysis is typically used to develop a small signal model of a converter and then depending on the type of control scheme used, the small signal model of converter is modified to facilitate the design of the compensation network. In contrast to a state space approach, PWM switch modeling develops a small signal of switching components of converterSystem level models are implemented using the Simulink in Mat lab. Thefollowing study provides details of methodologies for designing each component or block used in the switching regulator. Finally, simulation results are presented for voltage and V2 control schemes and their performance results are compared and inferences are drawnon the performance of current mode control. Keyword:Interleavers, iterative decoding, low-density parity-check codes, convolutional codes, turbo codes.

Dynamic Response Analysis of DC–DC Converter With Supercapacitor for Direct Borohydride Fuel Cell Power Conditioning System

The direct borohydride fuel cell (DBFC) is directly fed sodium borohydride as a fuel and hydrogen peroxide as an oxidant. The output voltage of the DBFC varies with respect to current demand. Therefore, it requires a dc-dc converter for a regulated output voltage. The dc-dc converter should be designed considering both the impact of the fuel cell and load disturbances to achieve wide range voltage regulation. This paper analyzes the impact of the DBFC impedance on the dc-dc converter. Based on the converter's small signal model including the DBFC impedance, the boost converter was evaluated. Impacts of the voltage and current control loops on the boost converter were investigated. Improved response time and stability of the DBFC dc-dc converter were observed by adding a supercapacitor between the DBFC and the dc-dc converter. Finally, two converter controllers, a nonlinear feedforward controller and a state feedback controller are proposed for further improvement of the dc-dc converter response time. A prototype 20-W dc-dc converter was built and tested to show the response improvement of the proposed analysis and control scheme.

Flyback converter with novel active clamp control and secondary side post regulator for low standby power consumption under high-efficiency operation

Flyback converters are widely used in industrial and commercial products because of their advantages of simple structure and low cost. Energy and environmental conservation have prompted interest in high efficiency and low standby power consumption in switch mode power supply applications. However, it is difficult to satisfy both conditions simultaneously because of conflicting design considerations. A novel active clamp control method is proposed for improving power conversion efficiency and reducing standby power consumption in a flyback converter. In addition, an asynchronous-type secondary side post regulator is applied to the converter for minimising standby energy leakage and improving cross-regulation performance for a multiple output channel flyback converter. Operational principles, control schemes, switch stresses and power consumptions are analysed using a converter small signal model and mathematical equations of converter waveforms. The superiority of the proposed converter is verified using experimental results on 110 W prototype.

Improved small-signal analysis for the phase-shifted PWM power converter

A closed form cycle by cycle analysis forms the basis for a new zero-voltage switching (ZVS) phase-shifted PWM (PSPWM) full bridge power converter small-signal model. The paper derives the small-signal response equations. The PSPWM converter has an implicit slew interval, making the converter dynamics difficult to analyze using traditional averaging techniques. The converter control to output transfer function under continuous conduction mode operation and using voltage-mode control does not exhibit a second order pole associated with the output L-C filter, making it different from a conventional PWM converter. This new PSPWM converter model shows that the output L-C filter is separated into two real poles, with one pole held at constant frequency independent of operating conditions. A characteristic pole depends only upon the converter switching frequency and inductor values. This characteristic pole is fundamental to understanding the PSPWM converter natural and forced responses. The new small-signal model is shown to be in excellent agreement with experimental results.

Robust control of series parallel resonant converters

A robust controller is designed for the series parallel resonant DC/DC converter based on the linear quadratic Gaussian/loop transfer recovery (LQG/LTR) methodology. The controller structure, comprising a servo-compensator with an internal model, reference state observer, plant and disturbance state observer, ensures tracking of the reference voltage and rejection of system disturbances. The controller performance is insensitive to converter parametric and operational variations. The controller design is based on a converter small-signal model derived using the principles of the describing function and harmonic balance on the nonlinear time-varying converter equations. The controlled converter is shown by computer simulation to perform excellently well, with very good tracking and disturbance capabilities in the presence of changes of load and input voltage.