Control Of DC-DC Converter Research Articles

Design for boost DC-DC converter controller based on state-space average method

abstractThe accurate mathematical model of converter is very important in the process of designing high performance switch power. Nonlinear, multimodal and time-varying are the characteristics of the DC-DC converter. So it is necessary to study it in a new way. This paper presents a mathematical model of Boost converter circuit by state space average method. The closed-loop PI controller based on the Boost converter model was designed. The static and dynamic performance of the closed-loop system was tested in Simulink which demonstrated a good behavior of the system to meet the requirements of user.

Complex non‐linear phenomena and stability analysis of interconnected power converters used in distributed power systems

Distributed power systems are considered to be a key element of future power grids. Their main characteristic is the local production and consumption of energy that is accomplished using a number of power converters that interconnect local sources and loads. In this paper, a current mode controlled dc-dc converter which feeds another current mode controlled dc-dc converter is considered to meet the demands of the load. It shows that the existence of the second converter at the output has destabilising effect on the overall system. Such a system may also exhibit interactions of various types of instability that conventional modeling methods cannot predict. Slow-timescale oscillation in standalone switching converters is usually attributed to the occurrence of a Neimark-Sacker bifurcation of the fundamental periodic orbit of the discrete-time model of the system. But in the studied cascaded system, the underlying mechanism is quite different. This paper fully explains the mechanisms as well as the conditions of the occurrence of such instabilities by employing the analytical and numerical tools of the exact switched model of the system. These results can be useful for developing design guidelines to avoid such problems. Finally, the results have been validated experimentally.

Closed Loop Control of Bi-Directional DC-DC Converter

Closed Loop Control of Bi-Directional DC-DC Converter

A Neural Network Based Reference Modified PID Control with Simple Duration Design for Digitally Controlled DC-DC Converters

The aim of this paper is to propose a neural network based reference modified PID control which has a simple duration design method for transient characteristics improvement of digitally controlled dc-dc converters. In renewable energy network systems, various types of dc-dc converters are widely used for power conversion and such converters require a superior control method for a stable operation. Especially, transient characteristics should be improved since they heavily affect the stability of the system. For such purposes, designing of conventional control methods becomes a difficult task since the optimization of control parameters needs complicated analysis and it is affected from variations of circuit components of converters. Therefore, simple and easy design of control is widely required for a stable operation of power converters. The neural network can provide a suitable control methodology for such situation since it treats the plant as a black box and it can realize a non-linear control based on training of the input-output relation without complicated modelling and analysis. On the other hand, the neural network based method has a disadvantage caused from the fact that the neural network is trained with data obtained in advance and an overcompensation phenomenon occurs in the transient response. In this paper, the neural network control is adopted to control the dc-dc converter in coordination with a conventional PID control. The neural network predicts the output voltage of the converter and the reference value in the PID control is modified with the predictions to reduce the error of the output voltage. To avoid overcompensation, a simple duration design for the neural network control is also provided to improve the transient response effectively. From prototype testing in simulation and experiment, it is revealed that the proposed method contributes to obtain a superior transient performance compared with the conventional PID control.

LMI approach for sliding mode control and analysis of DC-DC converters

Circuits' and in particular DC/DC converters' switching behavior is analyzed in this paper using the equivalent control modeling of the dynamic systems' sliding mode regime. As a representative example and also being one of the0 most complex circuits among DC/DC converters, the Cuk converter is chosen. It is shown how the converter's behavior in the steady state regime can be studied and analyzed by the linear matrix inequalities based stability conditions for linear dynamic systems with nonlinear sector bounded perturbations. The maximization of the nonlinear sector bound provides a limit for applying the linear ripple approximation in the converter operation analysis. Furthermore, our approach is validated by providing simulation results for two different switching surfaces of practical interest.

Second Order Sliding Mode Control of DC-DC converter used in the Photovoltaic System according an Adaptive MPPT

This paper deals with an adaptive maximum power point tracking (MPPT) of photovoltaic systems controlled by a second order sliding mode. The main goal of the proposed work is to track the maximum power point (MPP) using adapted algorithm. In addition, the use of the second order sliding mode control (SOSMC) can reduce the chattering phenomenon and ensure high transient response for a wide range of desired current or voltage under parameter variations. The proposed control is tested under different operating conditions. All results confirm the effectiveness of our proposed algorithm.

Dynamic Characteristics of Integral Gain Changeable Digital Control DC-DC Converter for Suppression of Output Capacitance

Stability of power converters has become more and more important in the hybrid green energy system because of its difficulties to maintain a stable dc-bus. This paper presents dynamic characteristics of a digital integral gain changeable control dc-dc converter to realize the high stability with suppression of the output capacitance. The integral gain changeable control method uses a variable integral gain, which is changed by the value of load current. The stability analysis is conducted by Bode diagrams. It is shown that the transient response and stability of the integral gain changeable method are better than the conventional fixed integral gain control method even if the output capacitance is smaller than the conventional method. Simulation and experimental results show the effectiveness of our concept presented.

Wide Input and Load Integral Gain Changeable Digital Control DC-DC Converter

The aim of this paper is to present an integral gain changeable digital control dc-dc converter with wide input and load regulation characteristics. Since the green energy depends on the environment, wide input regulation characteristics are necessary in dc-dc converters. Additionally, dc-dc converters have an issue that the output voltage of dc-dc converters is increased in the light load condition. When the large feedback gain is used to realize wide regulation characteristics, the stability becomes worse. The proposed method can address all of them using a simple integral gain changeable method. The integral gain is changed quickly by the load current value. The integral changeable function uses a single approximate function which is designed by the stabilization range of output voltage based on the integral control. The proposed method has great regulation characteristics against both of the input voltage and load. Furthermore, it has a superior transient response to the conventional integral gain fixed method. Simulated and experimental results are provided to confirm the effectivity of proposed method.

Lyapunov Based Adaptive-Robust Control of the Non-Minimum phase DC-DC Converters Using Input-Output Linearization

In this research, a combined adaptive-robust current controller is developed for non-minimum-phase DC–DC converters in a wide range of operations. In the proposed nonlinear controller, load resistance, input voltage and zero interval of the inductor current are estimated using developed adaptation rules and knowing the operating mode of the converter for the closed-loop control is not required; hence, a single controller can be employed for a wide load and line changes in discontinuous and continuous conduction operations. Using the TMS320F2810 digital signal processor, the experimental response of the proposed controller is presented in different operating points of the buck/boost converter. During transition between different modes of the converter, the developed controller has a better dynamic response compared with previously reported adaptive nonlinear approach. Moreover, output voltage steady-state error is zero in different conditions.

An integrated Control Approach and Power Management of Stand-alone Hybrid Wind/PV/Battery Power Generation System with Maximum Power Extraction Capability

The production of electricity from renewable energy sources likewind and photovoltaic energy has increased in recent years, due to en -vironmental problems and the shortage of traditional energy sources.In this article we present a detailed mathematical model and a controlscheme for hybrid wind and PV based DG system with battery and max-imum power extraction capability for isolated mode of operation. Thewind power generation system uses wind turbine (WT), a permanentmagnet synchronous generator (PMSG), a three-phase diode rectifierbridge, DC/DC boost converter with maximum power point tracking(MPPT) controller. The PV generation system uses PV array, a boostconverter with maximum power point tracking controller. Both sourcesand battery are connected to common dc bus with a dc link capacitorand supply power to load through PWM voltage source inverter. Theoverall control system consists of MPPT controller for both Wind andPV power system, a bi-directional dc-dc converter controller for batteryenergy storage management and load side inverter controller for volt -age and frequency regulation. Control strategies for individual systemcomponents of the proposed system are designed with a view to achievean acceptable level of voltage and frequency regulation while extract -ing the maximum power from wind and PV system. The performanceof the developed hybrid system is investigated in terms of voltage andfrequency regulation capability under changing wind, solar irradiation and variable load conditions.

Modelling and Analysis of Voltage Mode Controlled Luo Converter

This paper presents the analysis of open loop power stage dynamics relevant to voltage mode control for elementary Luo DC-DC converter for certain specific applications like Hybrid Electric Vehicles, fuel cell vehicles. A comparative analysis is carried out on positive output super lift series of converters to evaluate voltage gain, output voltage ripple, stresses on the switches and efficiency. The most suitable converter is modelled and verified using State Space average method and Circuit averaging technique. The transfer function from duty cycle to output voltage and input voltage to output voltage are derived. The transfer function can be used in modelling the complete luo converter when voltage mode control is used. Also a simple efficiency modelling technique is proposed with computer simulation using MATLAB/SIMULINK that confirms the predicted results.

A Simple Boost Shoot through Control for Single phase Quasi ZSI DC-DC Converters Based on Voltage Doubler Rectifier

A Simple Boost Shoot through Control for Single phase Quasi ZSI DC-DC Converters Based on Voltage Doubler Rectifier

A Modified Maximum Power Point Tracking Control for Bi-Directional Z-Source DC-DC Converter Based Solar Electric Vehicle

A solar electric vehicle is powered by photovoltaic arrays which allow for direct conversion of solar energy into electrical energy. Since space and weight are very limited with any vehicle, it is desired that the maximum possible amount of energy be obtained from the employed photovoltaic arrays. Every photovoltaic array has an optimum operating point, called the maximum power point (MPP), which varies depending on cell temperature and solar insolation level. This paper is focussed to find the mechanism best suited for employment in a moving vehicle to optimally track this point of maximum efficiency under rapid variation of solar insolation and adjust the operating point of the photovoltaic array accordingly. An integral part of any modern day electric vehicle is power electronic circuits comprising DC-DC converters for conversion and conditioning of electrical power. Recently, Z-source DC-DC converters show promising outcomes when integrated with photovoltaic array compared to conventional DC-DC converters. They provide larger range of output dc voltage, improve reliability and can reduce in-rush and harmonic current. A bi-directional Z-source DC-DC converter with a maximum power point tracking (MPPT) technique suitable for electric vehicle applications is developed to incur high electric power from photovoltaic array. The photovoltaic array output voltage is controlled and the maximum power point tracking is attained by controlling the duty cycle. The well known incremental conductance MPPT algorithm is modified by measuring the power in the middle of the sampling interval to prevent the bewilderedness during rapidly changing insolation condition. Computer simulation and experimental results are provided to establish the performance of the proposed system.

Capacity Limitation Control of Multiple Bi-directional DC-DC Converters for Micro Grid Application

The micro grid system requires battery for energy storage and power management. In which, the bi-directional DC to DC converter is the key component for maintaining the DC bus voltage and controlling the charge and discharge of the battery with or without grid support. Parallel control of multiple DC to DC converters is a critical technique to enlarge the power capacity. This paper presents two capacity limitation control methods that multiple DC to DC converters can be paralleled with distributed battery banks. The first method is the capacity limitation control with cascaded load current sense needing no control interconnection. The second method is the capacity limitation control with master-slave and cascaded current command limitation. Two methods are presented to solve the limitation of droop control method and active current sharing method respectively, and can be extended without converter number limitation theoretically. Three prototype 240W bidirectional half-bridge DC to DC converters are built and paralleled in this paper. The proposed method is confirmed with some measured results.

Buck-Boost DC-DC Converter Control by Using the Extracted Model from Signal Flow Graph Method

In this paper, the signal flow graph technique and Mason gain formula are applied for extracting the model and transfer functions from control to output and from input to output of a buck-boost converter. In order to investigate a controller necessity for the converter of assumed parameters, the frequency and time domain analysis are done and the open loop system characteristics are verified and the needed closed loop controlled system specifications are determined. Finally designing a controller for the mentioned converter system based on the extracted model is discussed. Then, a modern control design method is employed for regulator design. For this purpose, a full state feedback control for pole placement is applied. The simulation results are used to show the performance of the proposed modeling and regulation method.

Continuous-Time Delta-Sigma Controller for DC-DC Converter

This paper describes applications of a Delta-Sigma (ΔΣ) modulator to control a DC-DC converter. We propose to use a continuous-time (CT) feed-forward (FF) ΔΣ controller in a DC-DC converter and show that its transient response is faster than discrete-time (DT) and/or feedback-type (FB) ΔΣ controllers. We have also performed experiments of a DC-DC converter with a first-order continuous-time feedback ΔΣ controller and show its results.

PWM-Geometric Modeling and Centric Control of Basic DC–DC Topologies for Sleek and Reliable Large-Signal Response

Traditional linear techniques are widely used for the control of basic dc-dc converters due to their simple implementation. However, due to the small-signal validity range of the models employed, the converters usually perform poorly under large transients, and the dynamic response can be improved only to a limited extent in order to ensure a stable behavior. On the other hand, faster dynamic response can be achieved with boundary controllers, which require faster sensors and more powerful processors. A novel control scheme that combines the advantages of fixed-frequency pulsewidth modulation with state-plane geometric analysis is introduced to obtain fast and reliable large-signal response. The natural evolution of the average state variables is described by a large-signal unified model, which provides the basis to develop a reliable nonlinear control scheme. The proposed technique is suitable for implementation in low-cost digital signal processors, using low-bandwidth sensing stages, and it features fast, sleek, and consistent dynamic response with constant switching frequency. Since the model developed accurately predicts the large-signal behavior, reliable and predictable responses can be obtained at any operating point. In this way, the transient response obtained shows reduced, consistent, and well-determined peaks in inductor current and capacitor voltage, avoiding magnetic saturation and system failures even during extremely large transients. Furthermore, the maximum rating specifications for the reactive components can be reduced, which, combined with the low requirements for sensors and processors, lowers the implementation cost and makes the controller a very appealing alternative for high-volume applications. The contributions made to the theoretical and applied field are valid for any combination of reactive components due to the normalized approach adopted. The theoretical concepts are supported by detailed mathematical procedures. The proposed theory and controller are validated by experimental results.

Sampled-Data Modeling of Switched- Capacitor Voltage Regulator With Frequency-Modulation Control

The development of systems-on-chip requires embedded power management solutions due to the large number of power domains. The switched-capacitor voltage regulator is a suitable candidate as capacitors may be integrated whereas inductors still suffer limitations in that respect. Literature covers proposals of optimized power stages and several dedicated controllers for switched-capacitor DC-DC converters. Unfortunately the results do not cover systematic stability analyses. The paper proposes an original and systematic approach for the stability analysis of a switched-capacitor voltage regulator using sampled-data modeling. An application is given for a one-phase converter with a frequency-modulation based controller. The stability of the open-loop and closed-loop model is proposed and can be extended to multi-phase configurations.

아날로그 메모리를 이용한 DC-DC컨버터 제어기 설계

This research presents a DC-DC converter controller implemented with an analog memory. The structure of the converter will contribute to solve the stability problem unavoidable in a conventional closed loop converter. The analog memory will be used for realizing CAM(Contents Addressable Memory) which contains the output of the converter and the relevant duty ratio, respectively. The operation for reading in the memory is executed with an absolute differencing circuit and a WTA(Winner-Take-All) circuit suitable for a nearest-match function of the CAM. We also present a system architecture that enables highly-paralleled fast writing and quick readout as well as high integration density.

PWM-Based Sliding Mode Controller for Three-Level Full-Bridge DC-DC Converter that Eliminates Static Output Voltage Error

This paper proposes a pulse width modulation (PWM)-based sliding mode controller (SMC) for a full-bridge DC-DC converter that can eliminate static output voltage error. Hysteretic SMC in DC-DC converter does not have a fixed switching frequency, and applying hysteretic SMC to full-bridge converters is difficult. Fixed-frequency SMC, which is also called PWM-based SMC, based on equivalent control overcomes these shortcomings. However, the controller order reduction in equivalent control in PWM-based SMC causes static output voltage error. To resolve this issue, an integral item is added to the PWM-based SMC. Sliding mode coefficients are designed by applying a standard second-order system to the sliding mode surface. The effect of adding an integral item on the controller is analyzed, and an integral coefficient design method is proposed. Experiment results on a three-level full-bridge DC-DC converter verify the control scheme and design method proposed in this paper.