Discontinuous Conduction Mode Research Articles

Steady-State Analysis of Asymmetrical Pulse-Width-Modulated Series Resonant Converter for Light Load Condition

This paper proposes a steady-state analysis of the asymmetrical pulse-width-modulated series resonant converter, commonly employed under light load conditions for effective voltage regulation. The proposed method achieves precise and explicit converter waveforms by applying the Laplace-based theorem to the converter’s ordinary differential equation with periodic and discontinuous inputs, without relying on approximations. By numerically determining the intermediate variables that define converter waveforms, the analysis provides accurate steady-state results based on system parameters. Furthermore, it derives an analytical solution to identify the load conditions suitable for asymmetrical pulse-width modulation operation, as well as the boundary load conditions for discontinuous conduction mode within this mode. The mathematical expressions derived for the converter waveforms and operational modes are validated through simulations using a switching model in PSIM software, as well as through experimental results.

Precise Excitation of a Switched Reluctance Machine under Regenerative Mode in High-Speed Operation

The implementation of electric machines in electric and hybrid electric vehicles offers some advantages, including the ability to operate in regenerative mode. Switched reluctance (SR) machines have been alternative solutions due to their characteristics. Operating an SR machine in propulsion mode requires high torque and minimal torque ripple, while producing optimal output power in regenerative mode is required. In high-speed operation, when the back electromotive force is greater than the DC link voltage, single pulse-based methods are often used. Torque ripple problems can be neglected due to rotor inertia. In this paper, a single pulse-based control for SR machines in high-speed operation under regenerative and discontinuous conduction modes is analyzed. Excitation to magnetize the rotor and generation process to produce output power are compared to determine the effectiveness of energy saving during regenerative mode. By using a simple control strategy, precise excitation angles can be obtained to turn the machine on and off. Experimental work has been done to support the analysis. They show that by using proper excitation angles, the optimal output power can be generated.

Novel Quasi-Z-Source Inverter with High-Frequency AC Link of High-Proportion Renewable-Energy Power System

Z-source/quasi-z-source inverters can make up for some limitations of traditional voltage-/current-source inverters. In recent years, more and more research has been carried on z-source/quasi-z-source inverters, but most of them are unable to realize input/output galvanic isolation. The proposal of high-frequency isolated z-source/quasi-z-source inverters greatly enriches the topological family of this type of converter but places relatively high voltage stress on the capacitors. In this paper, a novel circuit topology of a quasi-z-source inverter with a high-frequency AC link of a new high-proportion power system is proposed. The operating principle and abnormal operating states, such as discontinuous-conduction mode (DCM) operation and abnormal states caused by component failures, are analyzed. The double closed-loop control strategy is analyzed and designed, and a grid-connected photovoltaic system based on the inverter is designed. The experimental results verify that the presented inverter has advantages such as high-frequency electrical isolation, bi-directional power flow, lower voltage stress on the capacitors, etc.

Design of a High-Voltage Miniaturized Control System for Macro Fiber Composites Actuators

Macro Fiber Composites (MFCs) exhibit significant potential in active control applications. These include vibration control for unmanned aerial vehicle wings and helicopter rotors. However, the high-voltage drive requirements of MFCs present challenges. The miniaturization of the controller is a mandatory condition in order not to affect the overall space utilization. Thus, this paper presents a specialized miniaturized high-voltage control system designed specifically for MFC actuators. The proposed system employs a mixed analog-digital modulation method (ADM). This method precisely regulates a discontinuous conduction mode flyback switch-mode power supply operating in current mode. The system achieves an adjustable high-voltage output range of -500 V to 1500 V. The mixed control system consists of several components. These include a switching power supply, a voltage divider circuit, a bleeder circuit, and a digital controller. Additionally, this high-voltage control system integrates with a Simulink software environment. The system is compact and lightweight. It also features high load capacity, high power, and excellent dynamic response. Moreover, it offers real-time control capabilities. Experimental validation on a high-aspect-ratio wing demonstrates that this control system achieves a vibration reduction effect of 65%. The miniaturized control system provides a valuable research base for vibration control studies.

High gain multi-stage DC-DC boost converter using improved switched-inductor network with reduced voltage stress

ABSTRACT This article proposes a high-gain DC-DC boost converter employing an improved switched inductor (ISI) network coupled with CLD (capacitor-inductor-diode) cell (ISI-CLD-BC). The ISI network is further extended to an n-stage configuration, providing a multistage structure that enhances the attractiveness of the proposed converter for achieving high voltage gain. By Integrating a CLD cell at the load side, voltage stress across the active switch is reduced, enabling utilisation of lower-rated MOSFETs with reduced on-state resistance, thereby enhancing cost-effectiveness as well as efficiency. Furthermore, the CLD cell has the advantage of increasing the output voltage. The proposed converter’s steady-state performance in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is fully studied. Furthermore, the efficiency is analysed by evaluating different power losses of different elements. A small-signal model is derived for the proposed converter to evaluate the non-minimal phase condition followed by a PI controller design under closed-loop conditions. An exhaustive comparative study is conducted between the proposed converter and recently developed high-gain converters by considering various performance indices. Finally, the proposed converter is simulated in MATLAB/Simulink software and an experimental setup is created and tested to ensure its validity and efficacy.

Modified input-to-output and control-to-output transfer functions of a non-ideal buck converter working in discontinuous conduction mode

Small-signal models of a buck converter working in the discontinuous conduction.mode that are available in the literature usually can be divided into those which contain.a single pole and refer to non-ideal converters and those that describe ideal converters and.contain two poles. Even though the models are noticeably different they have been validated.through simulations and measurements, which suggests both of them are correct. The.purpose of this paper is to provide a comprehensive comparison of the existing models with.transient simulations done in OrCAD software and through measurements, to show that both.of the mentioned models are true for a specific set of converter parameters, and to propose.a two-pole, control-to-output and input-to-output transfer functions of a non-ideal buck.converter, that can be used in any buck converter working in discontinuous conduction mode.

Bridgeless Cuk PFC converter with full load range soft switching operation by using a simple auxiliary circuit

This paper proposes a fully soft-switched bridgeless Cuk converter for power factor correction. The main converter utilizes a common ground structure with a single switch, simplifying the trigger signal generation and eliminating the need for positive and negative half-line cycle detection. This switch operates under Zero Voltage Switching (ZVS) enabled by a simple auxiliary circuit with just one switch. This auxiliary switch achieves Zero Current Switching (ZCS). Full soft switching allows for increased switching frequency without compromising efficiency, leading to a reduction in the size of passive components. Additionally, the shared ground between input and output minimizes Electromagnetic Interference (EMI) noise. The converter operates in Discontinuous Conduction Mode (DCM) to simplify the control circuit and inherently provides power factor correction without requiring an input filter due to the presence of input inductor and continuous nature of the input current. To validate the theoretical analysis, a laboratory prototype with 200 W output power, 80V output voltage, and 150kHz switching frequency is implemented. The results demonstrate the maximum theoretical and experimental efficiency of almost 96.2% and 95.8%, while, the full load theoretical and experimental efficiency is around 96% and 95.4%, in sequence. Also, an input current Total Harmonic Distortion (THD) and Power Factor (PF) of around 5.2% and 0.998 at full load is achieved, respectively.

Optimal Design and Analysis of High-Frequency Isolation Transformer for Switched-Mode Power Converters

High-frequency (HF) transformers have gained great interest in recent years due to the advent of powerful soft magnetic materials with low core loss in semiconductor power switches. Also, the optimal design of the HF transformer is a significant issue for high-performance energy conversion systems. In this paper, a 40W 50/12.5/25 V universal input and two output discontinuous-conduction mode (DCM) flyback transformer is designed by using mathematical calculations and analyzed via 3D ANSYS/Maxwell simulation including electromagnetic and loss analysis. It is shown that the simulation results accounting for hysteresis losses, eddy current losses, copper losses, and magnetic flux density determine the accuracy of the mathematical model calculation. Analyzes are performed at 100 kHz frequency levels. Results obtained will include core magnetic flux density, core/copper losses, leakage/magnetizing inductances, windings parasitic capacitances, input/output voltage, current values, and all design parameters. Finally, the proposed HF transformer's overall efficiency is calculated and presented. Significantly, the HF transformer achieves 97.8% efficiency thanks to the transformer's core and coil selection, B-H and B-P characteristics, one-to-one dimension design, and mesh operation. The dynamic and mathematical results of the designed transformer demonstrate the design and efficiency success

Predictive control method with conduction mode detection to suppress input current distortion of three‐level power factor correction

AbstractA novel predictive control method with conduction mode detection is proposed to suppress input current distortion of three‐level power factor correction (PFC) converters. In PFC converter, the input current is mostly distorted in continuous conduction mode (CCM) with conventional control methods. The proposed predictive control method comprises of a predictive CCM algorithm, a predictive discontinuous conduction mode (DCM) algorithm, and a conduction mode detection technique. By analysing four switching states of PFC converter and based on the inductor current ripple, predictive control duty cycles in CCM and DCM are derived, and the optimal duty cycle is determined by forecasting the next cycle current. According to the duty cycle characteristics, the conduction mode is detected without additional detection algorithms and circuits, achieving the input current tracking the input voltage. Finally, the effectiveness and correctness of the proposed predictive control method are validated through simulation and experiment.

A Systematic Method for Studying the Use of DC/DC Converters With Three Discontinuous Conduction Modes as Automatic PFCs

A Systematic Method for Studying the Use of DC/DC Converters With Three Discontinuous Conduction Modes as Automatic PFCs

Efficient power factor correction in single phase AC–DC boost converter for retrofitted electric bicycle battery charging: A finite element analysis approach

This research paper describes modifying a conventional bicycle into an electric bike by retrofitting it with a single-phase boost power factor correction (PFC) rectifier for low power battery chargers. The proposed work was designed and developed in a single stage, as opposed to the traditional two-stage chargers used to charge E-bicycle, to provide the desired outcomes of enhanced efficiency, good power quality, and dependability due to the charger's lower cost. Additionally, the proposed converter uses a single switch, which reduces not necessary body diode conduction and circulating current and enhances the PFC device's thermal management. Additionally, this research makes use of the diode bridge rectifier (DBR) arrangement, which offers low current stress and is suitable for electric bicycles. The converter operates at a low cost with reduced magnetics (DCM) by operating the charger in discontinuous conduction mode at such low voltage levels. It also accomplishes intrinsic power factor at the ac mains by employing a simple control method to maintain the battery in high power density constant current (CC) and constant voltage (CV) states. A thorough state space investigation is carried out in combination with modeling and testing to ensure that the electric bicycle charger operates effectively. Consequently, low power chargers are a good fit for the proposed single stage front-end converter, and a 250 W hardware prototype is used to verify the findings.

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.

High‐frequency digitally adaptive pulse skipping modulated voltage‐mode controlled quadratic buck converter

AbstractThe quadratic buck converter is renowned for its steep step‐down capability. It encounters increased losses due to its high component count. In scenarios with light loads, switching losses become the dominant factor. Additionally, the presence of two right‐half plane zeros impairs transient response, even at high‐frequency switching operations. Incorporating this converter into the digital domain introduces an undesired phenomenon known as subharmonic oscillation, rendering the system unstable, albeit potentially mitigated over time—a drawback particularly undesirable for converters tasked with rapid load dynamics. This paper introduces an adaptive pulse skipping modulation scheme to control metal–oxide–semiconductor field‐effect transistor (MOSFET) switching actions, enhancing overall efficiency in discontinuous conduction mode. Furthermore, the effects of right half‐plane (RHP) zeros on stability are analyzed within these switching schemes. The proposed scheme is integrated with voltage‐mode control. Simulation and theoretical analyses are conducted to validate this converter. A flat efficiency of 89%to 86%for the load range of 25 to 700 mA is obtained, outperforming other existing schemes. The results demonstrate that the adaptive pulse modulation scheme effectively improves efficiency and stability in discontinuous conduction mode converters. This research provides valuable insights for optimizing power electronics systems with varying load dynamics.

Circuit topology aware GNN-based multi-variable model for DC-DC converters dynamics prediction in CCM and DCM

A regression model based on graph neural network, tailored for electric circuit dynamics prediction is introduced, providing converter performance predictions on converter circuit level and internal parameter variations. Regardless of the number of components or connections present in a converter circuit, the proposed model can be readily scaled to incorporate different converter circuit topologies. Moreover, the model can be used to analyse converter circuits with any number of circuit components and any control parameters variation. To enable the use of machine learning methods and applications, all physical and switching circuit properties such as converter circuits operating in continuous conduction mode or discontinuous conduction mode are accurately mapped to graph representation. Three of the most common converters (Buck, Boost, and Buck-boost) are used as example circuits applied to model and the target is to predict the gain and current ripples in inductor. The model achieves 99.51% on the R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2$$\\end{document} measure and a mean square error of 0.0263.

An improved solar step-up power converter for next-generation electric vehicle charging

This study proposes an innovative control strategy based on a quadratic equation derived from a core battery charging model. This strategy is applied to a solar step-up power converter (SSUPC), which is specifically optimized for electric vehicle charging. The model includes a 500 W SSUPC, controlled by a microprocessor, effectively converting low input voltage into high output voltage. The proposed control strategy allows the SSUPC to operate in discontinuous conduction mode, thereby achieving a higher voltage gain. In experiments with an input voltage of 20 V, the system was capable of outputting up to 480 V, while maintaining a low duty cycle of 0.3 and achieving a system conversion efficiency of 95 %. Furthermore, the SSUPC integrates a pyramid maximum power point tracking (MPPT) algorithm, initiating MPPT to capture the maximum power point when the solar output power is insufficient for electric vehicle charging, achieving an MPPT efficiency of 99 %. The developed charger is compact, boasts high power density, is cost-effective, and is well-suited for widespread application, meeting the 480 V charging requirements of electric vehicles.

Machine learning based feedforward voltage control for buck converters in envelope tracking applications

Tracking the voltage envelope of 5G base station power supplies poses a significant long-term challenge. To achieve fast and accurate envelope tracking, an efficient and high-frequency power electronics circuit and an excellent voltage controller are essential. This paper presents a novel machine learning (ML) based feedforward control method for precise voltage reference tracking. The method is exemplified using a standard buck converter in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). A feedforward neural network (FNN) is trained to capture non-ideal and non-linear effects in real circuits. An automated data collection system, developed with MATLAB and Simulink, facilitates data acquisition and model training process. The trained FNN predicts the duty cycle for the buck converter to generate the targeted output voltage and output power. A simulation model is built to validate the effectiveness of the FNN controller in envelope tracking applications.

Power factor preregulation in power supplies using modified single stage non-isolated interleaved Sepic converter with minimal part count

This paper pontificates on design and realization of low-cost single phase single stage modified interleaved Sepic (MILS) converter for power supplies. On contrary to the classical Sepic power converters, the introduced active power factor correction (APFC) converter involves simple idea of paralleling that enables low input and output ripples with minimal device count. The interleaving conceptualization also lessens current stresses and static losses. Also, this modified power processing converter reveals natural power factor correction (PFC) and zero current switching (ZCS) features by discontinuous conduction mode (DCM) operation. Furthermore, the practical corroboration of the proposed converter is built and tested for 250 W hardware model to affirm benefits with 92 % efficiency and their relevant outcomes are reported in this scope. Finally, the power quality (PQ) attributes like, input power factor (PF), total harmonic distortion (THD) over input current under stable and transient cases are disclosed to prove bettered PQ limits at the AC mains as prescribed by various IEEE-519 and IEC 61,000–3-2 standards.

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

A Deep Reinforcement Learning Approach to DC-DC Power Electronic Converter Control with Practical Considerations

In recent years, there has been a growing interest in using model-free deep reinforcement learning (DRL)-based controllers as an alternative approach to improve the dynamic behavior, efficiency, and other aspects of DC–DC power electronic converters, which are traditionally controlled based on small signal models. These conventional controllers often fail to self-adapt to various uncertainties and disturbances. This paper presents a design methodology using proximal policy optimization (PPO), a widely recognized and efficient DRL algorithm, to make near-optimal decisions for real buck converters operating in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) while handling resistive and inductive loads. Challenges associated with delays in real-time systems are identified. Key innovations include a chattering-reduction reward function, engineering of input features, and optimization of neural network architecture, which improve voltage regulation, ensure smoother operation, and optimize the computational cost of the neural network. The experimental and simulation results demonstrate the robustness and efficiency of the controller in real scenarios. The findings are believed to make significant contributions to the application of DRL controllers in real-time scenarios, providing guidelines and a starting point for designing controllers using the same method in this or other power electronic converter topologies.

Sigmoid function model of parallel-connected DC-DC converters and analysis of their dynamic characteristics.

Because of the manufacturing variations of circuit elements and the effects of parasitic parameters, the switching elements of parallel-connected modules cannot be synchronously switched. Consequently, the characteristics of these converters, which are multi-mode, high-order systems, cannot be comprehensively described using reduced-order models based on the symmetry of circuit topology and parameters. It is also difficult to fully describe the characteristics of these systems using discrete mapping models and averaged models. Therefore, we developed a smooth, sigmoid function-based continuous-time model for systems comprising parallel-connected buck converters with average current-sharing control. The proposed model provides a unified description of the continuous and discontinuous conduction modes of the system. The criteria for ensuring the stability of the system were derived based on the Floquet theory. The nonlinear dynamic behavior of the system and the effects of the key parameters on the stability of the system were investigated. The results showed that the system may undergo period doubling bifurcation, border collision bifurcation, and Neimark-Sacker bifurcation as the system parameters varied. The theoretical analysis and simulation results were verified experimentally. Our results provide a basis for the configuration of controller parameters.