Search Results (137)

In order to upgrade the ability of the traditional flyback converter to transfer energy to the load, a dual-flyback converter with two active clamping circuits is added, using the same clamping capacitor to recover the leakage inductance energy. Furthermore, no additional resonant inductor is needed, and both the switches have zero voltage switching (ZVS) to reduce the switching loss. In addition, full-wave rectification is used on the secondary side to decrease the output voltage ripple frequency, which makes it easy to design the output filter. Full article

This paper presents the results of an experimental study on the charging process of selected mobile device batteries using a dedicated charging system operating in the Universal Serial Bus Power Delivery (USB PD) mode. The charging circuit was developed in the Flyback topology using a power factor correction (PFC) circuit. A block diagram of the charging system under consideration and a block diagram of the measurement set-up are presented. Power resistors with different resistance values and two selected mobile devices with different built-in battery capacitances were used as the load of the charging system under test. The test results are presented as a function of load resistance and the State of Charge (SoC) level of the batteries used. The measurement results obtained are discussed. Full article

In this paper, a modular cell balancing circuit based on a bidirectional flyback converter (BFC) is designed, which is equipped with a symmetrical BFC for each cell. The primary side of all BFCs is in parallel with the battery pack, and the secondary side is connected to the individual cells. Such an input-parallel output-series structure allows for bidirectional and controllable energy transfer among the cells. The control of the charging/discharging for a specific cell can be realized by adjusting the PWM signal on the primary or secondary side of the corresponding BFC. Based on this, three cell balancing strategies are proposed: maximum voltage discharge (MXVD), minimum voltage charge (MNVC), and maximum and minimum voltage balancing (MX&MNB). For MX&MNB, which is essentially a combination of MXVD and MNVC, it controls the maximum voltage cell discharging and minimum voltage cell charging simultaneously, where the energy is transferred directly between the two cells with the largest voltage difference. A cell balancing prototype is built and tested to verify the feasibility and stability of the proposed strategy. All three proposed methods can implement cell balancing simply and effectively, while the MX&MNB provides a faster speed. Full article

The nonlinear dynamic characteristics of a peak current regulation fractional-order (FO) flyback converter, considering the fractional nature of inductance and capacitance, are investigated in detail. First, the discrete iterative model of the fractional-order (FO) flyback converter under 10 kHz operating conditions is accomplished using the application of the Generalized Euler Method (GEM). On this basis, bifurcation diagrams, phase diagrams, and simulated time domain diagrams are used to describe the nonlinear dynamic behavior of the converter. The nonlinear dynamics of the converter are investigated through bifurcation and phase diagram analyses. A comprehensive examination is conducted to evaluate the impact of key parameters, including input voltage, reference current, and the fractional orders of inductance and capacitance, on the system’s stability. Furthermore, a comparative analysis is performed with conventional integer-order (IO) flyback converters to highlight the distinctive characteristics. The findings demonstrate that the FO converter manifests distinct nonlinear characteristics, including period-doubling bifurcation and chaotic behavior. Moreover, for identical parameter sets, the FO flyback converter is found to possess a smaller stability domain but a larger parameter region for bifurcation and chaos compared to its IO counterpart. This behavior allows the FO converter to more accurately capture the nonlinear dynamic characteristics of the flyback converter. Simulation results further substantiate the theoretical predictions. Full article

UV-C LEDs, which offer short-wavelength characteristics and serve as an alternative to traditional UV mercury lamps, represent a new light source for applications in space decontamination and surface disinfection. This paper presents the design and development of a UV-C LED lamp driver circuit configured to operate with a DC-input voltage source for sterilization and germicidal purposes. The primary circuit integrates a modified buck converter with a flyback converter, resulting in an innovative single-stage, single-switch DC-DC power converter. Additionally, the proposed electronic driver recovers energy stored in the transformer’s leakage inductors, enhancing overall circuit efficiency. A prototype driver circuit with a 3.3 W power rating (10 V/330 mA) is developed for a UV-C LED lamp intended for sterilization and germicidal applications with a DC-input voltage source. The experimental results from the prototype circuit, tested at an 18 V DC input, confirm the functionality of the proposed electronic driver for UV-C LED sterilization and germicidal lighting. Additionally, the circuit achieves efficiency exceeding 91%. Full article

This paper presents a novel technique for controlling the Power Factor Correction (PFC) of a two-stage converter. The proposed solution operates the PFC in a special intermittent mode at a medium or light load. As a result, the flyback converter stage can be optimized to operate within a tight input voltage range, thus obtaining better efficiency and more compactness compared to a traditionally controlled two-stage converter. Circuit models of the converter have been developed to test the goodness of the proposed solution. Full article

Flyback converters are popular in various electronic applications due to their efficiency, galvanic isolation, and voltage stepping-up. However, their modeling and analysis present significant challenges. Traditional switched models offer high precision but require extensive computational resources, which is impractical for large-scale simulations. The alternative linear large-signal models are effective for studying stability near fixed operating points but fall short in capturing transient dynamics, limiting their use in the analysis and design of large or complex systems. This paper presents a novel nonlinear approach for representing a proportional–integral (PI) voltage-controlled flyback converter operating in continuous conduction mode (CCM) that accurately captures transients while reducing the computational burden. Numerical simulations in a study case confirm that the model effectively captures the converter dynamics under various conditions, achieving steady-state errors below 0.07% and accelerations up to 54×. These results facilitate efficient design iterations across a broad range of applications, including renewable energy systems, battery charging, and electric vehicles. Full article

The effective capacitance of the common mode port serves as a critical metric for assessing the common mode noise suppression capability of transformers in power converters. Conventionally, the evaluation of transformers in single-ended topologies, such as flyback converters, using a network analyzer necessitates a reference static point and a dynamic point at the transformer port. However, a full-bridge transformer without a center tap lacks a reference static point in both the primary and secondary stages. Consequently, this paper proposes an innovative measurement technique to evaluate the common mode noise suppression capability of full-bridge transformers. This method accounts for the intrinsic parameters of the transformer and refines the high-frequency equivalent circuit model for accurate measurement. Ultimately, the validity of the proposed model is confirmed through experiments conducted on a CLLC converter prototype, offering the industry a straightforward and efficient approach to assessing and testing the common mode noise suppression performance of transformers without a center tap. Full article

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. Full article

This paper proposes a gallium nitride (GaN)-based very-high-frequency (VHF) resonant flyback converter with integrated magnetics, which utilizes the parasitic inductance and capacitance to reduce the passive components count and volume of the converter. Both the primary leakage inductance and the secondary leakage inductance of the transformer are utilized as the resonance inductor, while the parasitic capacitance of the power devices is utilized as the resonance capacitor. An analytical circuit model is proposed to determine the electrical parameters of the transformer so as to achieve zero voltage switching (ZVS) and zero current switching (ZCS). Furthermore, an air-core transformer was designed using the improved Wheeler’s formula, and finite element analyses were carried out to fine-tune the structure to achieve the accurate design of the electrical parameters. Finally, a 30 MHz, 15 W VHF resonant flyback converter prototype is built with an efficiency of 83.1% for the rated power. Full article

This paper describes active battery balancing based on a bidirectional buck converter, a flyback converter, and battery cells by using the proposed chain-loop comparison strategy. The role of the bidirectional buck converter is to charge/discharge the battery pack. During the charging period, the converter is in buck mode, and its output is controlled by constant current/voltage; during the discharging period, the converter is in boost mode, and its output is controlled by constant voltage. The role of the flyback converter is voltage equalization of the battery pack, and its output is controlled by constant current. A chain-loop comparison strategy is used to control battery voltage equalization. In this work, three equalization modes, namely, charging balance, discharging balance, and static balance, were considered. The voltage difference between the maximum and minimum is 0.007 V after a balancing time of 19.75 min, 0.005 V after a balancing time of 24 min, and 0.007 V after a balancing time of 20 min for charging balance, discharging balance, and static balance, respectively. Full article

This paper proposes an effective method to improve the power efficiency of the flyback converter in the continuous conduction mode (CCM). The proposed converter uses a simple passive circuit to reduce the switching power losses. The current through the output diode can be shifted to a new branch where one diode, one inductor, and one auxiliary winding of the transformer are included. The output diode current can be reduced to zero for the zero-current switching of the output diode. The additional inductor is used to control the changing rate of the additional diode current to reduce the reverse-recovery current. Keeping the simplicity of the passive method, the proposed converter improves the power efficiency compared to the conventional converter. The circuit configuration and the operation principle are described. The design considerations are presented, including the simulation verification. The experimental results for a 45 W prototype are discussed to evaluate the performance of the proposed converter. The proposed converter has achieved a power efficiency of 93.5% for the rated load condition, improving the power efficiency. The applications of the proposed converter are also discussed for the future research directions. Full article

This paper addresses cross-regulation in dual-output flyback converters. An original analytical framework is developed to model the impact of a balancing capacitor connected among a transformer’s secondary windings in order to mitigate the cross-regulation among different outputs. To validate the proposed model, a prototype dual-output flyback converter was built and tested for a wide range of load unbalances. The measured cross-regulation error was compared with the theoretical predictions provided by the proposed model, obtaining a tight fit, which confirms the validity of the proposed approach. Full article

In this article, a multipurpose embedded system for testing organic photovoltaic modules is presented. It is designed to include all the features for real-time monitoring, data acquisition, and power conversion based on a Ćuk converter, providing useful data for scientific investigation of the outdoor operation of organic photovoltaic modules. The embedded system allows both the scan of the I–V curve and the continuous operation of the organic photovoltaic module, such as at its maximum power. Voltage and current at the terminals of the organic photovoltaic module under test and up to four temperatures are continuously measured and stored on a Secure Digital card. The communication interface allows the embedded system to connect with other instruments, such as irradiance sensors, with digital serial output. The embedded system is designed both for laboratory and in-the-field use: it can be powered either by the AC electrical grid or a battery, which can also operate as a backup battery. Galvanic isolation divides the embedded system into the field-side and the logic-side functional sections, providing improved noise immunity and safe operation. The main power distribution system within the embedded system is a +9 V bus; ultra-low-noise linear low dropout regulators provide the +3.3 V and +5 V regulated voltages to supply the analog and digital circuits within the logic-side section, and a flyback converter supplies the field-side section of the board. The proposed embedded solution is validated using an experimental setup built at SolarTechLab, Politecnico di Milano. The experimental results report the feasibility of the proposed embedded system. Full article

In this paper, partial energy processing is applied to the current sharing technique for multiphase LLC resonant converters. The proposed circuit consists of an LLC resonant converter and a flyback converter, where the flyback converter is only used for partial energy processing. The input voltage of the LLC resonant converter is fine-tuned by the flyback converter to solve the problem of a voltage gain difference between the two phases of the LLC resonant converter caused by the error of the resonant tank components, which prevents the output current from being nonequalized. Since the compensation power is much smaller than the output power, and only one phase will be during circuit operation, the impact on the overall efficiency is minimal. Due to the low dependence between the LLC resonant converter and the flyback converter, they are operated at different switching frequencies. In addition, due to the low dependence between each phase, the circuit can be expanded using odd and even phases. Full article