Converter In Discontinuous Conduction Mode Research Articles

Control of DC-DC boost converter in discontinuous conduction mode feeding a constant power load

This article presents a new control strategy for a DC-DC boost converter used to supply a constant power load. The designed controller allows regulates the converter output voltage to a required reference value. By designing the controller based on the reduced order averaged model of the converter and using a nonlinear control technique based on feedback linearization, a simple-to-implement and stable controller for both operating modes of the converter (continuous and discontinuous conduction modes respectively) is obtained. The designed control strategy is validated through simulation and experimental results, demonstrating good dynamic performance and stability in both conduction modes, under variations in reference values and significant load changes. In addition, a comparison of the performance and implementation costs between the control strategy proposed in this paper and two strategies proposed by other authors is included.

Averaged switch model of single-ended primary inductor converter in discontinuous conduction mode

Averaged switch model of single-ended primary inductor converter in discontinuous conduction mode

Generalized Pulse Width Modulation Switch Model for Converters Based on the Multistate Switching Cell in Discontinuous Conduction Mode.

This work introduces a generalized version of the pulse width modulation (PWM) switch model applied in the small-signal modeling of converters based on the multistate switching cell (MSSC) operating in discontinuous conduction mode (DCM). It consists of extending the concept formerly introduced by Vorperian for the representation of multiphase converters in DCM, yielding a circuit-based approach that does not rely on matrix manipulations unlike state-space averaging (SSA). The derived dc and ac models are valid for any number of switching states and any operating region defined in terms of the duty cycle, thus allowing for determining the voltage gain and distinct transfer functions. A thorough discussion of results is presented to demonstrate the applicability of the derived models to represent distinct configurations of the MSSC.

Efficient Power Factor Correction using Chaotic Artificial Bee Colony Algorithm-Based FOPID Controller in DC-DC Zeta Converters

Design and implementation of a Chaotic Artificial Bee Colony (ChABC) algorithm based Fractional Order Proportional Integral Derivative (FOPID) controller for Power Factor Correction (PFC) in Switched Mode Power Supply (SMPS) using DC-DC Zeta converter is proposed in this article. The dc-dc zeta converter has the advantages of high efficiency over a wide range of input and output voltages, an enormous power factor, low line current harmonics, and can convert voltages both up and down. Operating the converter in discontinuous conduction mode (DCM) achieves power factor correction and simplifies the control circuit. This article describes the design characteristics, operating principles, and controller design of the proposed converter. The design, analysis, modeling and advancement of the ChABC algorithm based FOPID controller in SMPS offers the better power quality and faster convergence of regulated output voltage. Simulation and experimental results are presented to verify power factor, % Total Harmonic Distortion (THD), output voltage regulation, stability, and robustness for various load, line, and reference voltages.

Fuzzy Control of a High-Performance Boost Converter in Discontinuous Conduction Mode and its Application to a Photovoltaic Pumping System

In this work, a fuzzy voltage controller design of a 1 kW high-gain, high-efficiency direct current converter operating in discontinuous conduction mode is developed. In this condition, the design of a conventional controller is more challenging. This converter is part of an autonomous photovoltaic pumping system without batteries consisting of four photovoltaic modules, a variable frequency inverter and an induction motor coupled to a pump. The boost converter is responsible for the voltage elevation of photovoltaic modules to a 311V direct current bus, which must not have oscillations for a good operation of an algorithm to track the maximum power point of the modules. The fuzzy controller was implemented in a digital signal processor device to control the boost converter, producing a response with an overshoot of 5.78%, settling time of 3.8s and zero error in steady state.

Input parallel–output parallel connected modular nonisolated DC‐DC converters with current self‐sharing capability operating in discontinuous conduction mode

AbstractThis paper covers the self‐sharing analysis of dc‐dc nonisolated converters with input parallel–output parallel (IPOP) configuration and operating in discontinuous conduction mode (DCM). The main contribution of the proposed system is its capability of providing self‐sharing of the currents on both sides of each individual converter, without average current sharing control, even in the face of parametric variations. This self‐balance only occurs for DCM. When the addressed converters operate in continuous conduction mode (CCM), the self‐sharing does not occur naturally under parametric differences among them, requiring the use of additional control loops. The use of self‐sharing converters in nonisolated converters simplifies the control system, it makes the modular solution being attractive for many applications, and it increases the power range that the DCM converters may be applied. This paper brings the theoretical study of self‐sharing of the current mechanism to six basic nonisolated converters operating in DCM. The self‐sharing is verified by experimental results, which are obtained from three modules of dc‐dc SEPIC converters. Both converters were designed to operate with 200‐V input voltage, 125‐V output voltage, 1500‐W rated power (500 W each module), and switching frequency at 30 kHz.

Modelling of SEPIC, Ćuk and Zeta Converters in Discontinuous Conduction Mode and Performance Evaluation.

High-order switched DC-DC converters, such as SEPIC, Ćuk and Zeta, are classic energy processing elements, which can be used in a wide variety of applications due to their capacity to step-up and/or step-down voltage characteristic. In this paper, a novel methodology for analyzing the previous converters operating in discontinuous conduction mode (DCM) is applied to obtain full-order dynamic models. The analysis is based on the fact that inductor currents have three differentiated operating sub-intervals characterized by a third one in which both currents become equal, which implies that the current flowing through the diode is zero (DCM). Under a small voltage ripple hypothesis, the currents of all three converters have similar current piecewise linear shapes that allow us to use a graphical method based on the triangular shape of the diode current to obtain the respective non-linear average models. The models’ linearization around their steady-state operating points yields full-order small-signal models that reproduce accurately the dynamic behavior of the corresponding switched model. The proposed methodology is applicable to the proposed converters and has also been extended to more complex topologies with magnetic coupling between inductors and/or an damping network in parallel with the intermediate capacitor. Several tests were carried out using simulation, hardware-in-the-loop, and using an experimental prototype. All the results validate the theoretical models.

SEPIC converter in discontinuous conduction mode: Small signal modeling and analysis

AbstractIn this article, a new approach is applied to solve the small signal state space average (SSA) model for pulse width modulated (PWM) single ended primary inductor converter (SEPIC) under discontinuous conduction mode (DCM) of operation. Authors proposed a novel approach to get duty ratio constrains that is based on variation of current in inductor. The approach used a unique correction matrix (M) in the modeling process and obtained better results for DCM. To demonstrate the whole technique, the SEPIC‐based power supply of 75 W is designed and system loop gain is derived with the help of this new technique. The frequency response of the proposed system is captured with the help of linearization technique using MATLAB Simulink platform. The frequency plot from the proposed techniques is much closer to simulation results as compared to conventional method. This claims high predictions for dc–dc converter operating in DCM with wide range of input supply. The proposed model is analyzed with previous SSA small signal modeling for comparative results on the basis of frequency analysis and stability. The experiment results of designed power supply have shown good power quality performance at 220‐V AC mains for light‐emitting diode (LED) lighting application.

Improved Power Quality Switched Mode Power Supply Using Buck-Boost Converter

In this work, The devices generally used in industrial, commercial and residential applications need to undergo rectification for their proper functioning and operation. The operation of the buck– boost converter in discontinuous conduction mode ensures inherent PFC operation and reduces complexity in control. Hence there is a need to reduce the line current harmonics so as to improve the power factor of the system. This has led to designing of Power Factor Correction circuits. This concept presents a power factor corrected (PFC) Buck–Boost converter-fed SMPS. This project deals with the design, analysis, simulation, and development of a power-factor-correction (PFC) multiple output switched-mode power supply (SMPS) using a Buck–Boost converter at the front end. Single-phase ac supply is fed to a pair of back-to-back connected buck–boost converters to eliminate the diode bridge rectifier, which results in reduction of conduction losses and power quality improvement at the front end. To observe the performance of this converter, a model based on the Buck Boost topology has been designed and developed software and implemented with Proportional-Integral (PI) and Fuzzy logic controller. The simulations are demonstrated in order to validate the effectiveness of the controllers in power factor improvement. By using MATLAB.

Nonlinear Stabilization Controller for the Boost Converter with a Constant Power Load in Both Continuous and Discontinuous Conduction Modes.

The operation of Boost converters in discontinuous conduction mode (DCM) is suitable for many applications due to the, among other advantages, inductor volume reduction, high efficiency, paralleling, and low cost. Uses in biomedicine, nano/microelectromechanical, and higher power systems, where wide ranges of input/output voltage and a constant power load (CPL) can coexist, are well-known examples. Under extremely wide operating ranges, it is not difficult to change to a continuous conduction mode (CCM) operation, and instability, chaos, or bifurcations phenomena can occur regardless of the conduction mode. Unfortunately, existing control strategies consider a single conduction mode or linearized models because only slight resistive/CPL power level or input/output voltage variations (and no conduction mode changes) were expected. In this paper, new mathematical models for the Boost converter (with resistive or CPL) that are conduction mode independent are presented and validated. Since the open-loop dynamics of the proposed CPL model is unstable, a nonlinear control law capable of stabilizing the boost converter regardless of the conduction mode is proposed. A stability analysis based on a common-Lyapunov function is provided, and numerical and experimental tests are presented to show the proposal’s effectiveness.

Discontinuous Conduction Mode Analysis of High Gain Extended-Duty-Ratio Boost Converter

A typical non-isolated photovoltaic (PV) microinverter requires a high conversion ratio in the dc-dc stage as well as needs to support a wide range of input-output voltage operation accommodating partial shading scenario. An extended-duty-ratio (EDR) boost converter is a good candidate for such application as it provides a high efficiency solution with a hybrid of interleaved inductor and switched capacitor configuration significantly lowering the switch voltage stress, switching losses, and providing inherent equal current sharing among the input phases. However, these advantages of EDR boost converter in continuous conduction mode (CCM) is only true for a limited duty ratio range. On the contrary, it is observed that the discontinuous conduction mode (DCM) can support a wider range of duty ratio operation, maintaining lower voltage stress on the devices and ensuring inherent equal current sharing among the boost inductors. Nevertheless, even in the DCM, the operation in the region with least voltage gain becomes very complex and requires a thorough understanding. This paper presents an extensive analysis of an EDR boost converter for DCM operation for all the operating regions. The operating characteristics of an EDR boost converter in DCM is analysed and its gain is derived. The detailed analysis presented in this paper enables in designing the components and judiciously deciding the operating range of EDR boost converter in DCM operation for any application. In order to verify the analysis, the simulation and experimental results from a 300 W EDR boost hardware prototype are also provided.

Performance optimisation of the grid‐connected flyback inverter under improved hybrid conduction mode

In the unfolding-type interleaved two-switch flyback inverter (ILTFI) operating in discontinuous conduction mode (DCM), the hybrid control strategy combining the one-phase DCM and the two-phase DCM has a significant impact on improving the efficiency under all load conditions. In the situation where the marginal power of this control strategy is increased, the converter may enter CCM. Consequently, the converter cannot track the reference current and the output current quality is notably decreased. To tackle this issue, a novel hybrid control method is proposed which varies the switching frequency based on the output power. The proposed approach is immune to the loss analysis and power losses of the components. Hence, it is independent of components selection and their characteristics. In this case, the smooth transition between the one-phase and the two-phase operation modes is guaranteed without affecting the output power quality and the stability of the converter in DCM. The control complexity of the proposed scheme is low and the converter can be easily controlled in DCM. The performance of the flyback microinverter with the proposed hybrid control scheme is verified by the simulation and the experimental results together with the loss analysis.

Theoretical and Experimental Analyses of Dynamic Performance of Three-Level Buck Converters in Discontinuous Conduction Mode for Standby Mode Power Supply

Theoretical and Experimental Analyses of Dynamic Performance of Three-Level Buck Converters in Discontinuous Conduction Mode for Standby Mode Power Supply

A Current-Fed LCL Resonant Converter for Wide Output-Voltage Applications

This article proposed a novel current-fed LCL resonant converter with a simple structure by multiplexing inductors and switches for wide output voltage applications. With three different pulsewidth modulation methods, the proposed converter can work at three voltage gain modes, namely high gain (HG), medium gain (MG), and low gain (LG). In HG mode, it has a higher voltage gain than the conventional LCL converter by an extra boost energy storage stage. In MG mode, it operates similarly as a conventional LCL converter. In LG mode, it is equivalent to a flyback converter in discontinuous conduction mode (DCM), which achieves higher efficiency and is easier to be controlled than an LCL converter. In these three modes, all power switches and rectifier diodes can obtain soft-switching performance, increasing the power conversion efficiency. The operating principle, design methodology, and control scheme are explained and verified by a laboratory prototype with 520 W output power, 30–150 V output voltage.

A Modified Luo Converter-Based Electric Vehicle Battery Charger With Power Quality Improvement

Most of the single-stage single switch power factor correction (PFC) solutions have limited applications in high power ac–dc converters as an increased voltage across and current through the semiconductor devices are seen, which, in turn, results into lower efficiency. This article deals with a modified isolated Luo PFC converter-based electric vehicle (EV) charger with two switches and input clamping diodes at the primary of an isolation high frequency transformer (HFT). This configuration facilitates the advantage of comparatively low switch voltage stress, which is clamped at the input voltage. The proposed converter is selected to operate in discontinuous conduction mode (DCM) to obtain built-in PF correction capability at ac mains. The operation of the converter in DCM, considerably reduces the control complexity due to reduced number of sensors. A prototype is implemented to verify the improved power quality (PQ) performance of the proposed modified Luo converter. An improved low ripple-based charging is provided in constant current-constant voltage modes, which improve the long-term battery service life. The performance of the converter is found robust enough to validate the efficacy of charging at steady state and at varying line voltage variation range. The improved PQ indices are observed to meet the international standards of IEC 61000-3-2.

High-efficiency Bidirectional Buck–Boost Converter for Residential Energy Storage System

This paper proposes a bidirectional dc–dc converter for residential micro-grid applications. The proposed converter can operate over an input voltage range that overlaps the output voltage range. This converter uses two snubber capacitors to reduce the switch turn-off losses, a dc-blocking capacitor to reduce the input/output filter size, and a 1:1 transformer to reduce core loss. The windings of the transformer are connected in parallel and in reverse-coupled configuration to suppress magnetic flux swing in the core. Zero-voltage turn-on of the switch is achieved by operating the converter in discontinuous conduction mode. The experimental converter was designed to operate at a switching frequency of 40–210 kHz, an input voltage of 48 V, an output voltage of 36–60 V, and an output power of 50–500 W. The power conversion efficiency for boost conversion to 60 V was ≥98.3% in the entire power range. The efficiency for buck conversion to 36 V was ≥98.4% in the entire power range. The output voltage ripple at full load was <3.59 Vp.p for boost conversion (60 V) and 1.35 Vp.p for buck conversion (36 V) with the reduced input/output filter. The experimental results indicate that the proposed converter is well-suited to smart-grid energy storage systems that require high efficiency, small size, and overlapping input and output voltage ranges.

Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

Among various modeling methods for DC-DC converters introduced in the past two decades, the state-space averaging (SSA) and the circuit averaging (CA) are the most general and popular exhibiting high accuracy. However, their deduction approaches are not entirely equivalent since they incorporate different averaging processes, thus yielding different small signal transfer functions even under identical operating conditions. Some research studies claimed that the improved SSA can obtain the highest accuracy among all the modeling methods, but this paper discovers and clearly verifies that this is not the case. In this paper, we first review and study these two modeling methods for various DC-DC converters operating in the discontinuous conduction mode (DCM). We also streamline the general model-deriving processes for DC-DC converters, and test and compare the accuracy of these two methods under various conditions. Finally, we provide a selection strategy for a high-accuracy modeling method for different DC-DC converters operating in DCM and verified by simulations, which revealed necessary and beneficial for designing a more accurate DCM closed-loop controller for DC-DC converters, thus achieving better stability and transient response.

Current-Mode Pulse Train Controlled Quadratic Boost Converter Operating in Discontinuous Conduction Mode

Unlike the conventional pulse width modulation control, a unique current-mode pulse train (CMPT) control technique presents a different nonlinear dynamics associated with the power electronics system. The quadratic boost converter in discontinuous conduction mode (DCM) is examined under CMPT control. The control performance of the system is studied by analyzing the combination of high-power control pulse PH and low-power control pulse PL of a control pulse repetition cycle in regulating the output voltage. The computer simulation is accomplished to capture the gist of the system dynamics revealing the periodic transition manifested due to border collision bifurcation under the influence of the variation in input voltage and load resistance. The stability of the system is assessed with the evidence of loci of eigenvalues from two-dimensional discrete-time model and maximal Lyapunov exponents obtained using QR decomposition algorithm. An experimental setup is also developed to verify the simulated and analytical dynamics witnessed.

A Versatile OCP Control Scheme for Discontinuous Conduction Mode Flyback AC/DC Converters

This study presents a versatile over current protection (OCP) control scheme, which can be widely used in discontinuous conduction mode (DCM) flyback converters. The proposed scheme can not only reduce the variation of output current caused by different line voltages, but also improve the performance of DCM converters in start-up, dynamic response, and the overload protection (OLP) process. It consists of an OCP compensation circuit and a current-pump circuit. Instead of being a constant value, the peak voltage across the sense resistor in a converter that uses the proposed circuit will oscillate with time when the converter regulates a constant output current. To verify the feasibility and performance of the proposed circuit, an IC controller that uses the proposed OCP circuit has been designed and fabricated in 0.35-μm 5-V/40-V high-voltage CMOS technology. Experimental results show that the constant output current precision of the prototype is within ±1% when the input line voltage changes from 90 to 265 Vac. In other tests including start-up, dynamic response, and the OLP process, the performance of the proposed prototype shows an improvement of 9%–19% over conventional converters.

Impedance Matching in Wireless Power Transfer

Impedance matching is a common issue in a wireless power transfer (WPT) system. This paper summarizes impedance matching methods reported in the literature and gives a theoretical analysis on dc-dc converter for impedance matching in a WPT system. A buck-boost converter in discontinuous conduction mode has the characteristic of that the input resistance is independent of the load resistance and the input voltage, which seems to be suitable for impedance matching. Furthermore, the impedance matching ability of buck-boost converter will not depend on the frequency of rectifier, because it implements the solution to the dc output of rectifier. To verify those, we give several application examples of this buck-boost converter applied in rectifiers with different frequencies, such as 2.45, 5.8, and 24 GHz. As a result, those rectifiers with the buck-boost converter achieve a constant RF-dc conversion efficiency over an extremely wide load range. In addition, it is also successfully utilized in a microwave power transmission system for driving a dc motor.