Modeling Of DC-DC Converters Research Articles

Dynamic Compensation Control Strategy for DC Converter Based on Linear Optimal Quadratic

Aiming at the problem of DC bus voltage fluctuation, a DC-DC converter control method combining LQR (Linear Optimal Quadratic) and dynamic compensation control is proposed. Firstly, the state space model of DC-DC converter is established. Secondly, according to the following characteristics of LQR controller, the error of the controlled output is introduced into the integral control as an extended state to eliminate the output tracking error. Then, in order to suppress the voltage fluctuation caused by load switching of DC-DC converter during power grid operation, a dynamic compensation structure based on disturbance observer is designed through robust coprime decomposition and Euler parameterization theory. The structure compensates directly at the input of the current loop, and the compensation controller Q(s) is calculated by model matching. Finally, the simulation is carried out by Matlab / Simulink. The results show that without changing the structural parameters of the original system, the new control architecture can effectively suppress the DC bus voltage fluctuation caused by load theft and power fluctuation, and enhance the anti-interference performance and dynamic performance of the system.

Average model of DC-DC converters including the effect of coil resistance for practical analysis

This paper presents the mathematical model of practical DC-DC converters using state space analysis. The work illustrates the effect of coil resistance on the output voltage of Buck converter and Boost converter. For checking the validity of the mathematical model, it has been compared to the existing Buck Converter and Boost Converter based models of MATLAB Simulink. The small-signal analysis of DC-DC converters aids in the steady-state determination of the operating point of high gain DC-DC converters.

A Detailed Full-Order Discrete-Time Modeling and Stability Prediction of the Single-Phase Dual Active Bridge DC-DC Converter

The standard methodology to obtain the model of a power electronic converter is achieved by averaging the state-space dynamics of the converter’s state variables. But the average of the transformer current is null over a switching cycle in the resonant dc-dc converter. Therefore, the conventional method is not suitable for resonant converters, including the phase-shifted bidirectional dual active bridge (PSBDAB) converter. The two-time scale discrete-type models can resolve the problem associated with the standard state-space averaging methodology. The time-scale segregates the dynamics of the PSBDAB converter into fast and slow state variables, which can be modeled separately and eases the analysis of the PSBDAB converter. The effect of the core-loss of the inductor, dead-time of the semiconductor devices, output filter capacitor’s equivalent series resistance, semiconductor on-resistance, and the transformer copper loss components are included in the model to improve its steady-state and dynamics characteristics. Moreover, the stability analysis using a bifurcation diagram is carried out for the digitally controlled closed-loop of the system. Furthermore, the critical gain for the stable region with variations in the circuit parameters like load resistance, circuit equivalent inductance, and voltage demand is extensively studied. The modeling and stability analysis is validated in the simulation and experimental setup. The results verify that the proposed method accurately predicts the stable region with variations in the system circuit parameters. Thus this study provides a guide to select and tune the controller parameter to ensure the converter operates within the boundaries of the stable region.

A New Dynamic Model of a Dual Active Bridge DC-DC Converter

The paper proposes a new model for a dual active bridge DC-DC converter. The model is developed in time-domain and it takes into account the effective waveform of all the quantities of interest. The paper introduces some algebraic and integral operations useful for modeling the converter defining some “support functions”. Starting by these functions a full analytical model of the DAB is deduced. The effectiveness of the suggested analytical model has been tested and confirmed by simulations and experiments with a 3 kW prototype 28/270 V.

Modelling and Control Design for Full Bridge DC-DC Converter

Abstract: In this paper, modeling and analysis of full bridge dc-dc converter is present using state space averaging technique. Isolated dc-dc converter is widely used in power applications. Mainly full bridge dc-dc converter is used where high power and high voltage required. The transformer is used here to produce a higher voltage in secondary voltage side. PI controller is used to stabilize the output of the converter. Simulation is done for getting different outputs by giving same input. To observe the stability and transient response results are obtained using matlab simulink. Keywords: Full Bridge, DC-DC converter, state space, isolated, transient response.

МОДЕЛЬ ПЕРЕКЛЮЧАЕМОЙ ШИМ-СТРУКТУРЫ ДЛЯ АНАЛИЗА ИМПУЛЬСНЫХ ПРЕОБРАЗОВАТЕЛЕЙ НАПРЯЖЕНИЯ С ПРОИЗВОЛЬНОЙ ТОПОЛОГИЕЙ

The article considers the problems of analyzing DC-DC voltage converters and analyzes the advantages, disadvantages, as well as the scope of full switched and averaged continuous models of the converters. The feasibility of using the complex of two models (full switch model and averaged continuous model) for analyzing their operation is proved. The general approach to the construction of continuous models of DC-DC voltage converters based on state-space averaging method is considered. Disadvantages of the averaged models using a classic approach are shown. The relevance of the development of universal continuous models of DC-DC converters is substantiated. The possibility of creating such models using averaged models of PWM switching structure included in the DC-DC voltage converter is shown. Analyzed the typical structure of the switch-mode power supply with feedback. An averaged model of the switching structure is proposed, basing on which continuous models of DC-DC converters with any topology can be built. The processes occurring in this switching structure in the mode of continuous and discontinuous choke current are analyzed. A method for constructing continuous models of the main types of DC-DC voltage converters based on switching structure averaged model is proposed. The adequacy of continuous models obtained by this method has been proven. The results of modeling transients on the continuous and full switch models for inverting voltage regulator are demonstrated. The possibility of accounting in the model of active resistances of switches and cumulative choke is shown. The possibility of using the proposed model to obtain the open loop transfer functions is demonstrated, in particular, the characteristics of the duty factor - output voltage. These transfer functions can be used to synthesize control system compensating circuits of the switch-mode power supply. The possibility of using a single generalized averaged model of the switching structure to build continuous models of converters with complex topology using both the Voltage Mode and Current Mode is shown. This creates prerequisites for developing a universal averaged continuous model for DC-DC converter based on this principle

Research on Modeling and Control Method of DC-DC Converter

Since mankind entered the industrial society, DC-DC converters have been used in many industries. The function of the DC-DC converter is a module that converts DC voltage into DC voltage, which can also be called a power processing system. The main content of this article is to explain the basic principles of Buck converters, and perform modeling and simulation on the MATLAB platform to prove the feasibility of expectations.

Research on CLLLC Resonant Bidirectional DC-DC Converter

Based on the single-phase full-bridge LLC DC-DC converter, the LC series resonant network is introduced in the secondary side of the high frequency transformer to form the bidirectional CLLLC resonant DC-DC converter. Firstly, the bidirectional CLLLC resonant DC-DC converter was used for mathematical modeling. By extending the description function, the large-signal steady-state model of the converter was obtained, and the DC voltage gain when the DC-DC converter was running forward was deduced. The gain characteristics and frequency characteristics of the model are compared with those of the basic wave equivalent model. Secondly, the small-signal perturbation model of CLLLC DC-DC converter is modeled, and the small-signal perturbation is brought into the large-signal steady-state solution to obtain the transfer function when the CLLLC resonant converter is running forward. Finally, a 20kW CLLLC DC-DC converter is designed, and the simulation analysis is carried out to verify the correctness of the proposed scheme.

Design of LLC Resonant Type Full-Bridge DC-DC Converter

In order to develop and utilize renewable energy reasonably, the problems such as the increasingly intensive power load, insufficient power supply capacity and short power supply radius in major cities should be overcome. In this paper, a LLC resonant DC-DC converter is proposed for low voltage distribution network. Firstly, the energy transmission model and mathematical model of DC-DC converter under different modes are analysed. Secondly, the parameters of the resonator are designed. Finally, the simulation platform is built, and the simulation and experiment of DC-DC converter under different working conditions are carried out to verify the correctness of the proposed scheme.

Multy-modality Switch Modeling and Simulation of A Three-port DC-DC Converter

A three-port DC-DC converter (TPC) for photo-voltaic (PV) electric vehicle (EV) was presented in this paper. A PV module and a battery consist of the power supply for electric vehicle. A boost converter helps the PV module to output maximum power. A sepic-zeta converter helps the battery to be charged by PV power or output power for EV. A cuk converter was used to keep the stability of output voltage for load. There are five modalities for the TPC model and three applications were simulated to verify the performance of different modality switching. The simulation results show that the given TPC model have some advantages, such as small steady errors, short transient times and small fluctuation of voltage and power. This TPC can be used in EV to provide a steady voltage for motor and extend the driving distance.

The Time-Invariant Polynomial Model of Fixed-Frequency PWM DC–DC Converter Applying Normalized Coordinate Transformation

In this article, a time-invariant polynomial model of fixed-frequency pulsewidth modulation dc-dc converter is proposed. Through normalized coordinate transformation, the time-varying model of the converter is transferred into a time-invariant model, whose state matrix and input matrix are obtained by the addition and multiplication of matrices simply and expressed by the polynomial of duty cycle concisely. The proposed model has the following advantages. Compared with the state-space average (SSA) model, the ripple of the state vector and the switching period are considered, thereby improving the accuracy. Contrary to other time-invariant models, the state matrix and input matrix instead of the state vector are expanded into series. Therefore, neither the number of state vectors nor the order of the matrices increases, and the proposed model has a simple structure similar to the SSA model. In addition, as a time-invariant polynomial model, the calculation and analysis of the proposed model are much simpler than the time-variant exact model. In order to prove the above advantages of the proposed model, the general expression of the proposed model is derived and the proposed model is compared with other models. These analyses and comparisons are verified through the simulation and experimental results.

LMI-Fuzzy Control Design for Non-Minimum-Phase DC-DC Converters: An Application for Output Regulation

Robust control techniques for power converters are becoming more attractive because they can meet with most demanding control goals like uncertainties. In this sense, the Takagi-Sugeno (T-S) fuzzy controller based on linear matrix inequalities (LMI) is a linear control by intervals that has been relatively unexplored for the output-voltage regulation problem in switching converters. Through this technique it is possible to minimize the disturbance rejection level, satisfying constraints over the decay rate of state variables as well as the control effort. Therefore, it is possible to guarantee, a priori, the stability of the large-signal converters in a broad operation domain. This work presents the design of a fuzzy control synthesis based on a T-S fuzzy model for non-minimum phase dc-dc converters, such as boost and buck-boost. First, starting from the canonical bilinear converters expression, a Takagi-Sugeno (T-S) fuzzy model is obtained, allowing to define the fuzzy controller structure through the parallel distributed compensation technique (PDC). Finally, the fuzzy controller design based on LMIs is solved for the defined specification in close loop through MATLAB toolbox LMI. Simulations and experimental results of a 60 W prototype are presented to verify theoretical predictions.

Research on typical fault classification method of DC-DC converter

DC-DC converter is the core component of power conversion module of integrated modular avionics. Condition monitoring and fault diagnosis of DC-DC converter can effectively improve the reliability of avionics equipment, reduce the maintenance cost and greatly improve the use efficiency of aircraft. In this paper, firstly, a typical DC-DC converter model based on SEPIC topology is designed in PSPICE environment, and the failure modes of DC-DC converter are analyzed. Secondly, the typical fault types of DC-DC converter are simulated, and the corresponding original data are obtained through simulation. Finally, the processing framework including data preprocessing, feature extraction and selection, and multi model fusion is used to do fault classification of the DC-DC converter. The fault diagnosis of the converter is simulated. Simulation results show the effectiveness of the proposed method.

Modelling of DC-DC Converter for Solar Based Electric Vehicle

Presently a days we are searching for substitute sources like electric vehicles, to chop down the contamination from cars which are developing quickly. In electric vehicles, A DC-DC converter is used to boost the voltage from solar photo voltaic (PV) array and isolated bidirectional DC-DC converter (IBDC) is used to charge and discharge the battery. In this paper, the proposed utilization of quadratic twofold lift converter (QBC) instead of DC-DC converter, which has high increase when contrasted and ordinary converter. In disengaged bidirectional DC-DC converter, delicate exchanging is accommodated lessen the turning misfortunes and weights on switches. The proposed two DC-DC converters are demonstrated and mimicked utilizing MATLAB Simulink and results are appeared in this paper.

Small-Signal Stability Analysis Method for Hybrid AC–DC Systems With Multiple DC Buses

Hybrid AC-DC systems integrate ac bus and various dc buses as well as multiple power electronic converters, and such systems are consequently vulnerable to instability issues. In order to investigate the stabilities of hybrid AC-DC systems with multiple dc buses and identify which converters are mainly responsible for instability, this article proposes a stage-by-stage stability analysis method. The small-signal models of AC-DC and DC-DC converters are established, based upon which the whole system is separated into multiple stages according to its structure, and checked stage-by-stage. Make sure that equivalent input admittance (or impedance) of stage $k(k=2, 3, \ldots)$ has no right-half-plane poles so that it is self-stable, then consider the equivalent input admittance (or impedance) of stage $k$ as the equivalent load admittance (or impedance) of stage $k-1$ , and check the stability of stage $k-1$ ; and repeat the process until the whole system has been checked. All stage being stable can ensure the stability of overall system. The converters that are mainly responsible for instability can be clearly identified by this stage-by-stage method, and it could be beneficial for stability enhancement of the system. The effectiveness of the proposed method is verified by simulations in PSCAD/EMTDC and experiments of the control hardware in the loop (CHIL).

Computationally Efficient Modeling of DC-DC Converters for PV Applications

In this work, a computationally efficient approach for the simulation of a DC-DC converter connected to a photovoltaic device is proposed. The methodology is based on a combination of a highly efficient formulation of the one-diode model for photovoltaic (PV) devices and a state-space formulation of the converter as well as an accurate steady-state detection methodology. The approach was experimentally validated to assess its accuracy. The model is accurate both in its dynamic response (tested in full linearity and with a simulated PV device as the input) and in its steady-state response (tested with an outdoor experimental measurement setup). The model detects automatically the reaching of a steady state, thus resulting in lowered computational costs. The approach is presented as a mathematical model that can be efficiently included in a large simulation system or statistical analysis.

Comprehensive energy efficiency analysis of series hybrid electric vehicles with dual-phase-shift-controlled DC-DC converter

By considering converter fundamental operating principles, the paper first derives a complete set of analytic expressions of the overall power losses of a conventional Dual Active Bridge (DAB) bi-directional DC-DC converter under Dual Phase Shift (DPS) control. Expressions for conduction and switching losses in the electronic devices acting as the converter switches, and copper and core losses in the isolation transformer, are derived and accounted for in the DC-DC converter model. DPS control involves many more converter operating conditions, in comparison to the more common single-phase-shift (SPS) control, which makes the analytic power loss characterization of a DPS-controlled converter an arduous task. Subsequently and by employing the derived analytic converter power loss model with exemplary parameter values, the paper analyzes the efficiency of a high-fidelity full hybrid electric vehicle (HEV) model that includes a DAB DC-DC converter, under a wide range of realistic driving conditions and converter operation, including low- to high-speed driving, and converter DPS operation. Two popular hybrid powertrain energy management schemes, the Thermostat and Power Follower control strategies, are used to simulate the vehicle model to reinforce the range of realistic vehicle operating conditions. The results show that in series HEV applications more accurate modeling of DC-DC converter models than conventional constant efficiency models is required to predict converter losses, and also the fidelity in the characterization of converter losses can have a significant impact on the vehicle fuel consumption prediction.

Novel Design Methodology for DC-DC Converters Applying Metaheuristic Optimization for Inductance Selection

Nowadays in modern industrial applications, where the power supply efficiency is more important than the output noise performance, DC-DC converters are widely used in order to fulfill the requirements. Yet, component selection and precise estimation of parameters can improve the converter’s performance, leading to smaller and more efficient designs. Hence, metaheuristic optimization algorithms can be applied using the mathematical model of DC-DC converters, in order to optimize their performance through an optimal inductance selection. Therefore, this work presents a novel design methodology for DC-DC converters, where the inductance selection is optimized, in order to achieve an optimal relation between the inductance size and the required energy. Moreover, a multi-objective metaheuristic optimization is presented through the Earthquake Algorithm, for parameter estimation and component selection, using the inductance of a buck DC-DC converter as a case study. The experimental results validate the design methodology, showing ripple improvement and operating power range extension, which are key features to have an efficient performance in DC-DC converters. Results also confirm the Small-Signal Model of the circuit, as a correct objective function for the parameter optimization, achieving more than 90% of accuracy on the presented behavior.

Small-Signal Modeling of Open-Loop PWM Tapped-Inductor Buck DC–DC Converter in CCM

A tapped-inductor buck dc-dc converter uses the tapped-inductor to further step-down the output voltage. This article presents a small-signal model of a tapped-inductor buck dc-dc converter by using the circuit averaging technique. The obtained nonlinear model is linearized to derive its linear large-signal, small-signal, and dc models. The small-signal model is then used to derive open-loop transfer functions namely, control-to-output voltage transfer function and the input-to-output voltage transfer function. MATLAB was used to obtain their respective Bode plots and later validated experimentally using a gain-phase network analyzer.

Stability Analysis of DC-DC Converters Applying Lie Algebra

ABSTRACT Stability analysis of switched DC-DC converters is necessary because instability enhances current ripple and causes converter operation at unwanted voltage/current level. In the present study, stability analysis of switched converters using Lie Algebra has been performed considering the switched linear model of DC-DC converters. The switched linear system is asymptotically stable if the Lie bracket formed by the state matrices of the system is commutative. The Lie Algebra is generated and its derived series is also computed. The Lie Algebra is found to be solvable, consequently the switched system is exponentially stable under arbitrary switching. The effect of duty cycle variation and load resistance of DC-DC converters, working in continuous conduction mode (CCM) on the decay constant and decay coefficient, has also been studied. The decay coefficient and decay rate of this exponentially stable system are observed to increase with an increase in the duty cycle for a specific load resistance.