DC Converter System Research Articles

Firefly Algorithm-based Optimization of Control Parameters in DC Conversion Systems

Sustainable energy and electric vehicles require DC-DC converters in renewable energy systems, EV charging, and smart grids. In this context, buck converters are crucial, providing efficient voltage regulation and reliable performance in these advanced energy systems. While Proportional-Integral (PI) controllers are widely adopted for their simplicity and dependability, they often rely on manual parameter tuning, limiting their adaptability and responsiveness. To address this limitation, this research introduces a digital control strategy that optimizes the PI parameters using the Firefly Algorithm (FA). This optimization significantly enhances the stability and reduces the oscillations in the DC-DC buck converter. A MATLAB/Simulink simulation model is utilized to validate the proposed approach, and the results demonstrate that the FA-optimized control parameters substantially improve the converter's performance, making it highly suitable for high-demand applications in advanced energy systems.

Design and implementation of time-based fault tolerance technique for solar PV system reliability improvement in different applications

This paper investigates the application of time-based fault tolerance techniques in solar photovoltaic (PV), DC–DC converter, battery, and permanent magnet synchronous motor (PMSM) systems. The fault tolerance techniques are like open circuit switch-level, leg-level, module-level, and measurement-level. By leveraging time-based monitoring and analysis, these techniques enable early detection, isolation, and recovery from various faults, enhancing system reliability and availability. The study focuses on fault scenarios within the 0.15–0.3 time per/second frame, a critical window for rapid fault response. Specific techniques, including time-based fault detection, isolation, and recovery strategies are explored in detail. The OPAL-RT HIL testing platform is used to validate the simulation results and conduct tests to evaluate the efficiency of various methods. The results demonstrate the performance of the fault-tolerant systems and the implementation of effective time-based techniques in solar PV applications. Finally, this work can be useful for researchers who want to learn how solar PV systems, batteries, and PMSM systems behave in fault situations followed by the conclusion.

A novel PWM plus phase shift modulation strategy for three‐level isolated dual‐active‐bridge DC–DC converters

Abstract A hybrid‐three‐level isolated dual‐active‐bridge (HTDAB) DC–DC converter is widely used for grid‐interactive power converters. However, a traditional extended‐phase‐shift (EPS) modulation scheme would cause voltage‐level‐disorder (VLD) problems in HDAB DC–DC converter system because the output voltage of HTDAB would be clamped at a high‐ or low‐level during power transmission when the inductor current changes directions. Thus, the zero voltage sequence of the HTDAB cannot be stably maintained under EPS control, which not only leads to a significant difference between the actual transmission power and the target output power but also seriously affects the stability of the system control. To address this limitation, the reasons leading to VLD are analysed in detail, that is, an inappropriate PWM switching sequence at the output zero voltage level would occur under EPS control. Then, a novel PWM plus phase shift (PPS) modulation strategy is proposed, which can eliminate VLD completely. Finally, an experimental prototype is built to verify the effectiveness of the proposed PPS modulation scheme. The experimental results demonstrate that the PPS modulation method proposed in this article can effectively eliminate level disturbances and improve system stability.

New Integrated DC–DC Conversion System for Electric Vehicles

New Integrated DC–DC Conversion System for Electric Vehicles

Enhancing wind power conversion efficiency with Vernier DSPM generator and sliding mode control

To enhance the efficiency of wind power conversion systems, a DC conversion system that combines a wind turbine with a battery is introduced in this paper. The Vernier Doubly Salient Permanent Magnet (V-DSPM) generator at the center of this system, designed for low speeds and high torque, eliminates the need for troublesome gearboxes. The proposed control employs MPPT based on tip speed ratio with output as the reference current of the boost converter and a sliding mode control-based Gao’s constant plus proportional rate reaching law to track the reference current. Three tests were performed to determine the efficiency of the proposed strategy. Moreover, a comparison with a conventional PI controller was carried out. The simulations were performed using MATLAB and Simulink. The obtained results show that the system with SMC has better performance than the system with PI.

An Improvised Modulation and Control Approach for Dual Active Bridge DC–DC Converter System

Aimed at the control and modulation of dual active bridge bi-directional dc (DAB-BIDC) converter, an unconventional approach is applied to explore its effect in symmetrical wave-based isolated dc-dc converters. The existing control schemes of DAB-BIDC converter with unified or optimal phase shift (UPS/OPS) modulation have the constraints like complex control schemes, light load efficiency, current stress, and reactive power. Since a 50 Hz, grid-connected conventional converter system uses the sinusoidal pulse width modulation method to minimize the requirement for passive filters. Similarly, this work investigates the same analogy for the high-frequency (HF) symmetrical wave converters to get effective modulation and control scheme for the DAB-BIDC converter. Furthermore, the proposed sinusoidal pulse width-phase shift (SPW-PS) modulation scheme has been implemented by the optimally derived control parameters using Lagrange's Multiplier Method (LMM) to minimize the reactive power flow and current stress reduction at the HF link. Therefore, the DAB-BIDC converter with the proposed modulation and control approach can be used for EV charging and solid-state transformers applications. Finally, the proposed work is validated using MATLAB simulation and experimental setup having turn ratio 36/12 V, fundamental frequency 5-kHz, and switching frequency 100-kHz for the experimental validation using OPAL-RT.

Modeling and Nonlinear Dynamic Analysis of Cascaded DC–DC Converter Systems Based on Simplified Discrete Mapping

As a basic structure of the distributed power systems, cascaded DC-DC converter systems have attracted a lot of attention. However, due to the interaction between the sub-converters, classic methods for modeling cascaded systems are either not accurate enough, such as state-space averaging model, or not simple enough, such as discrete-time mapping model, especially the systems with different switching frequencies. To overcome this drawback, a simplified discrete-time mapping modeling method for cascaded DC-DC converter systems is proposed in this paper. Based on the idea of state-space average, the original problem is simplified to modeling cascaded DC-DC converter systems with same switching frequencies. The proposed method is able to predict the dynamic properties of the system at all stages, such as slow-scale and fast-scale instabilities. Then, two-stage cascaded boost converter with different switching frequencies under peak current double loop control is taken as an example to present the simplified discrete-time mapping model. Finally, the effectiveness of the proposed method is verified by simulations and experiments.

A Dynamically Reconfigurable Recursive Switched- Capacitor DC–DC Converter With Adaptive Load Ability Enhancement

Multiple voltage conversion ratio (VCR) recursive switched-capacitor (SC) dc–dc converters, based on several basic 2:1 converters, are widely used for on-chip power supplies due to their flexible VCRs for higher energy efficiency. However, conventional multiple VCR SC converters usually have one or more 2:1 converters unused for some VCRs, which results in lower power density and chip area wastage. This article presents a new recursive dc–dc converter system, which can dynamically reconfigure the connection of all on-chip 2:1 converter cells so that the unused converters in the conventional designs can be reused in this new architecture for increasing the load-driving capacity, power density, and power efficiency. To validate the design, a 4-bit-input 15-ratio system was designed and fabricated in a 180-nm BCD process, which can support a maximum load current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{0.71}\,\text{mA}$</tex-math></inline-formula> and achieves a peak power efficiency of 93.1% with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$105.3\,\mu \text{A/mm}^{2}$</tex-math></inline-formula> chip power density from a 2-V input power supply. The measurement results show that the load-driving capacity can become 6.826×, 2.236×, and 2.175× larger than the conventional topology when the VCR is 1/2, 1/4, and 3/4, respectively. In addition, the power efficiency under these specific VCRs can also be improved considerably.

A Single-Stage Bridgeless Isolated AC–DC Conversion System for Light Electric Vehicles Charging Application

A 1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi $ </tex-math></inline-formula> single-stage ac–dc power conversion unit employing bridgeless isolated modified single-ended primary inductor converter (BLIMSEPIC) is presented in this work for the light electric vehicles (LEVs) charger applications. Unlike the existing SEPIC and Cuk high-power factor (HPF) ac–dc converters, the presented BLIMSEPIC HPF ac–dc converter incorporates continuous input and output current features while operating under discontinuous current mode (DCM) condition. Therefore, it demonstrates excellent applicability in charging applications. The DCM operation considerably simplifies overall control architecture, as the presented BLIMSPEIC ac–dc converter exhibits inherent power factor correction capability under DCM operation, and therefore, significantly reduces the cost of control implementation. Besides, the continuous input and output currents attribute lessen the filter’s size and associated losses. Furthermore, the reduced voltage stress and zero current switching of semiconductor devices, together with the front-end bridgeless structure, considerably improve the conduction and switching losses of the charger. The operation, design, control, and performance of the BLIMSEPIC HPF ac–dc converter are experimentally verified, and corresponding results are presented to justify its efficacy for LEVs charging applications.

Spectrum Estimation of Input Current Ripple on a Wide Class of Multilevel Grid-Tied Converters

Multilevel (ML) converters are frequently used to implement grid-tied ac–dc conversion systems. Their design may benefit from multiobjective optimization techniques, which typically involves time-consuming circuit simulations in order to obtain input current estimations suitable for input inductor and electromagnetic interference filter design. Herein, a closed-form expression of the input current ripple is derived to ease harmonic content estimations. The proposed approach separates the fundamental grid-current component from its ripple and models the latter like an amplitude modulation, where the modulating signal is its envelope and the carrier is the triangular current waveform. First, a general waveform analysis of ML converters is performed to derive the voltage across the grid-side inductor, then the associated current ripple is modeled. Experimental results on an ML converter prototype are reported to validate the analytical results.

A Partial Power Processing Structure Embedding Renewable Energy Source and Energy Storage Element for Islanded DC Microgrid

In the past ten years, because of less power transferred loss, the partial power processing (PPP) converter systems are extensively studied for embedding the renewable energy source (RES) into the strong grid system. Moreover, by combining the energy storage system (ESS), the RES can provide the required power for the consumer stably, but the RES is usually connected to the dc bus through dc–dc converter system without PPP characteristic. Therefore, in this article, a novel PPP structure, which can embed the RES and the ESS, is proposed for the islanded dc microgrid with robust dc-link voltage. Notably, this structure can deal with the small difference among different RES units as well as the difference between the total output power of RESs and the required power of consumer. Besides, in the proposed PPP structure, the RES should feature the limited range of voltage regulation such as photovoltaic (PV) and fuel cell. Then, the control requirement of the RES and the robust dc-link voltage can both be achieved. In addition, based on the dual-active-bridge (DAB) dc–dc converter, a DAB-based PPP converter system is proposed for verifying the effectiveness of the proposed PPP structure. Then, a high-robustness control scheme is proposed for maintaining the total dc-link voltage when the working condition of the RES, the output voltage of the ESS, and the power requirement of the consumer are changed. Furthermore, when output power of one RES unit is limited, the corresponding operation is also proposed. Finally, by using PV panel as an example, simulation results and experiment results are provided to verify the effectiveness of the proposed PPP structure and the proposed methods.

Robust Tracking Control of Dual-Active-Bridge DC–DC Converters with Parameter Uncertainties and Input Saturation

This paper proposes a method for robust tracking control synthesis of dual-active-bridge (DAB) DC–DC converters with parameter uncertainties and input saturation. In the proposed method, the nonlinear function of the phase shift ratio is expressed as a control input, and the phase shift ratio is determined by the one-to-one relationship with the control input. Especially, the proposed method is developed with consideration of the input saturation phenomenon that occurs physically in the phase shift ratio of DAB DC–DC converters. Furthermore, based on the proposed method, a set of exponential constrained stabilization conditions for DAB DC–DC converter systems with parameter uncertainties is provided to ensure a fast convergence rate. Finally, to verify the effectiveness of the proposed control method, various simulation results are provided and compared with the well-known improved model phase shift control (IMPSC) and load current feedforward (LCFF) control methods.

Small-Step Discretization Method for Modeling and Stability Analysis of Cascaded DC–DC Converters With Considering Different Switching Frequencies

Cascaded dc–dc converter is the main component of the dc distributed power system. It is valuable to establish the accurate model for studying the stability of cascaded dc–dc converters. However, the cascaded dc–dc system has many operating modes, such that the existing classic methods, e.g., state-space average model and discrete-mapping model, are difficult to explore to analyze cascaded dc–dc converter system, especially that with different switching frequencies. To overcome this drawback, this article promulgates a new modeling and stability analysis method for cascaded dc–dc converter. Small-step method, discretization method, and Euler method are exploited to modeling. All stages of the system are considered, therefore, accurate; and stability is divided into three categories according to the different definitions. Then, the cascaded systems with the same or different switching frequencies are studied using the presented method. As an example, two-stage peak current-mode controlled boost converter is scrutinized. Finally, simulations and experiments are manipulated to verify the correctness of the new method.

An Input-Oriented Power Sharing Control Scheme With Fast-Dynamic Response for ISOP DAB DC–DC Converter

With some advantages, such as electric isolation, high efficiency, and fast dynamic response, the input-series output-parallel (ISOP) dual-active-bridge (DAB) dc–dc converter has been regarded as one of the most promising candidates for connecting the medium voltage terminal and the low voltage terminal. For the ISOP DAB dc–dc converter, the existing control strategies are mainly focusing on the equivalent power sharing control, but the fast-dynamic response is not included and the decoupling between the regulation of input voltage and the adjustment of output voltage is not eliminated significantly. In this article, the average model of this ISOP DAB dc–dc converter is presented first, which can be employed to analyze the power distributions of this modular topology clearly. Then, an input-oriented power sharing control scheme with fast-dynamic response is proposed for ensuring both the power sharing ability and the fast-dynamic performance of the ISOP DAB dc–dc converter in this article. Compared with the existing methods, this proposed scheme can also significantly reduce the coupling between the power sharing control and the output voltage regulation. In addition, an inductance-estimating method is proposed for ensuring the power sharing performance of the ISOP DAB dc–dc converter. Finally, the experimental results are provided to verify the effectiveness of the proposed input-oriented power sharing control with fast-dynamic response for the ISOP DAB dc–dc converter system.

A Novel Multiport DC-DC Converter for Enhancing the Design and Performance of Battery–Supercapacitor Hybrid Energy Storage Systems for Unmanned Aerial Vehicles

This paper proposes an integrated multiport non-isolated DC–DC converter system for integrating battery–supercapacitor hybrid energy storage with photovoltaics for solar-powered unmanned aerial vehicles applications. Compared to the traditional topologies used, the proposed converter allows a size reduction of at least 20% of the supercapacitor by maximizing the utilization of the rated energy capacity. In addition, by proposing to use a phase-shifted carrier modulation technique, the inductors’ current ripple is reduced, which enables a further reduction in the inductor size. These improvements in capability and performance of the proposed topology are experimentally validated on a 500 W PV/battery–supercapacitor integrated power system prototype.

Modelling and Control of Ultra Capacitor-Based High-Gain DC–DC Converter System with Charge Equalization Circuits

Modelling and Control of Ultra Capacitor-Based High-Gain DC–DC Converter System with Charge Equalization Circuits

Bridgeless Isolated Positive Output Luo Converter Based High Power Factor Single Stage Charging Solution for Light Electric Vehicles

In this article, a high-power factor ac–dc conversion system based on bridgeless isolated positive output Luo converter is demonstrated for light electric vehicles charging. Unlike conventional bridgeless Luo converters, the presented topology ensures positive voltage polarity at its output and incorporates a minimum component count over the universal supply voltage range of 85 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> to 265 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> . Meanwhile, the volume of magnetic components and the charger's cost are reduced by considering a discontinuous inductor current mode (DICM) design. To accomplish desired charging profile of the battery, a simple control incorporating few sensing devices and single gate drive circuitry, is utilized. It is noteworthy that, the single stage bridgeless structure of the presented topology with DICM design considerably reduces conduction and switching losses of the charger. Finally, the presented topology is designed and modeled through MATLAB environment, and its efficacy is tested through a prototype in the laboratory environment. The critical test results at various operating conditions are demonstrated to verify design and control objectives of the charger. A brief comparative analysis with existing solutions, is presented to justify the effectiveness of the presented solution.

Global Optimal Cooperative Control of Multiple DC–DC Converter Systems for Dynamic Consensus

To improve the poor dynamic consensus in multiple dc-dc converter systems caused by parameter differences, this article proposes a global optimal cooperative control strategy. The proposed control strategy achieves dynamic consensus of output currents by minimizing a global performance index, which consists of local errors and neighbor synchronization errors. In this system, each converter is regarded as an agent in the communication digraph, so as to construct a cyber-physical model. Accordingly, a cooperative control method based on the linear quadratic regulator (LQR) is proposed, with the help of nonlinear coordinate transformation techniques. Different from conventional LQR, integral action is introduced to eliminate steady-state errors and improve coordinated performance. Meanwhile, the proof of the stability and consensus of the closed-loop system is given using Lyapunov approach. Moreover, the design guidelines to tune the dynamic response are provided through simulations. The experimental results further demonstrate the effectiveness and superiority of the proposed control method in a multiconverter prototype.

RANCANG BANGUN DC TO DC BUCK CONVERTER DENGAN SISTEM KENDALI PI PADA NI ELVIS II DAN ANTARMUKA BERBASIS LABVIEW

Understanding basic concepts is an important thing in electronics, especially regarding the teaching aid of power electronic components. Given the need for students to study the model of electronic schematic with feedback controller, a media that can support this is needed. One of the developments in component technology and electronic circuits that can be studied is the DC voltage conversion, namely the DC to DC buck converter. This teaching aid model uses software, namely LabVIEW and the control and data acquisition hardware, namely NI ELVIS II. DC to DC buck converter schematic that can reduce the variable output voltage with a value range of 6 - 18VDC from an input voltage of 24VDC. PI feedback controller testing in the system experiment resulted in a difference of 0.1567% error using the PI controller parameter of Kp = 3.00 and Ti = 0.01. The test results with the PI controller show the expected response and can be applied to the buck converter circuit system. Testing the interface of the buck type DC to DC converter system is considered feasible as a learning aid with an overall interface quality value of 83.8% with student responds.

Transient Mitigation Using an Auxiliary Circuit in Cascaded DC–DC Converter Systems With Virtual Impedance Control

Most dc power distribution architectures are organized as a typical cascaded converter system that is composed of source and load converters, and may experience a system oscillation due to the negative impedance effect of constant power loads. The load-side virtual impedance method is a possible solution to such stability problem, which however makes the dynamic response of the load converter slow, and thus increases the requirement of the filter capacitance. In this article, an auxiliary circuit that is connected to the output port of the load converter is proposed to enhance the transient performance of the power converter system, while the system can be stabilized by the virtual impedance method. The control and parameter design of the proposed auxiliary circuit is introduced. The capacitance requirement of the system for an expected transient deviation of the output voltage is significantly reduced by using the proposed auxiliary circuit. An example design is given to verify the feasibility of the proposed method with simulation analysis and experimental results.