Power Loss Breakdown Research Articles

Coupled Inductor Assisted High-Voltage Gain Half-Bridge Z-Source Inverter

A half-bridge-based impedance-source inverter with two T-shaped coupled inductors is proposed in this article. Unlike the conventional half-bridge structure, the proposed topology can generate a zero-voltage level at its output stage. First, the proposed configuration and its modulation method are described, which will analyze the topology's various operational modes. Second, the boost factor is determined, and a way to design the necessary passive devices is found. Third, a power loss breakdown study is investigated in order to devise a solution to improve the efficiency of the proposed structure. Fourth, various comparisons show the benefits and drawbacks of the presented design. These comparisons show that the proposed topology can provide a high boost factor when coupled inductors are used. Furthermore, it has reduced voltage stresses on the components, resulting in a smaller size and lower cost. Finally, the experimental results are obtained by employing a prototype designed by the methodology presented in this article. These results are used as a benchmark to determine whether the proposed topology works well. In addition, the power loss analysis and efficiency comparison are displayed.

High-Efficiency Quad-Mode Parallel PV Power Optimizer for DC Microgrids

The paper introduces a new parallel photovoltaic (PV) power optimizer intended for direct integration of PV modules into a dc bus or microgrid. The topology is derived from a typical galvanically isolated buck series resonant dc-dc converter (SRC) to the buck-boost SRC recently proven as a parallel PV power optimizer (PO). By applying the topology morphing control, this two-mode converter is extended to the quad-mode parallel PV PO. Its operation modes defined by changing modulation of switches are detailed, and gain expressions are provided. The proposed concept provides enhanced performance in the region where global power maximum could occur due to partial shading. Accordingly, a significant efficiency improvement is achieved at voltages below the nominal value that targets the most probable PV module operating point without shading. An experimental prototype was built to demonstrate the benefits of the proposed quad-mode PV PO and compare it to the existing two-mode buck-boost SRC. Thermal stress analysis is supported with power loss breakdown calculations to demonstrate component thermal stresses in critical operating points.

Optimized Multi-Carrier PWM Strategy and Topology Review for Multi-Cell Series-Parallel Medium-Voltage Rectifier

Solid-state transformer (SST) acting as a medium-voltage (MV) rectifier is a viable solution to supply low-voltage DC (LVDC) loads directly from the MV ac grid. Different from a classical boost-derived power-factor-correction (PFC) topology, the multicell series-parallel (MCSP) converter steps down and distributes the input ac voltage by multiple switching cells while providing the PFC function. We propose an optimized multicarrier pulsewidth modulation (PWM) strategy to avoid unwanted modes by modified multicarrier waveforms for ensuring frequent parallel connectivity to improve balancing effect while preserving simple current control implementation. Compared with conventional phase-shifted (PS) PWM and other modified multilevel carrier methods, the proposed method has no adverse effect on the input current distortion and optimizes the balancing effect on the capacitor voltages resulting suppressed circulating currents. Effectively reduced current stresses on the switch devices could lead a reduction of conduction loss on the device. Topology discussion, circulating currents, digital implementation, and loss analysis are provided. Finally, the superiority of the proposed PWM method is validated by thermal-based simulation presenting a power loss breakdown and comparing with other PWM methods. A full-scale prototype is developed, and the experimental outcomes verify the remarkable performance of proposed PWM scheme in balanced and even suppressed switch currents with improved system efficiency.

Bidirectional Isolated Hexamode DC–DC Converter

The proposed isolated buck-boost series resonant dc dc converter contains two full-bridge hybrid switching cells capable of half-bridge operation. This feature is regarded as topology morphing control. The voltage buck regulation requires special modulations applied to the primary-side hybrid switching cell. In contrast, the voltage boost regulation requires special modulations for the secondary-side hybrid switching cell. Combining the topology morphing control with the buck-boost regulation capability a novel dc-dc converter operating in six different modes is derived. Moreover, the proposed converter is capable of bidirectional operation. This paper describes how the topology morphing control influences the converter dc voltage gain, which results in three boost and three buck modes. The obtained six modes are described and equations for the converter dc voltage gain are provided. Selected design guidelines for the power part and control system are presented. Using those, a 350 W prototype was designed and built. Experimental results confirm the theoretical expressions for the converter dc voltage gain. Experimental efficiency is provided in a wide input voltage range for both energy transfer directions. Analysis of operating points with the highest thermal stress of components is presented with corresponding power loss breakdown calculations confirming measured thermal results.

A Generalized Method for Comprehension of Switched-Capacitor High Step-Up Converters Including Coupled Inductors and Voltage Multiplier Cells

High step-up converters are crucial in many power electronic interfaces, including for renewable energy sources. As the result of topological variation of high step-up converters, many topologies share similar characteristics. In order to have a clear understanding of an optimized design that makes the best use of components to achieve high gain, it is necessary to devise a generalized comprehension method for high step-up converters. This article presents a novel generalized method for analyzing single-switch step-up converters that can include switched capacitor (SC) cells, a coupled inductor (CI), and/or voltage multiplier cells (VMCs). The proposed method is neither dependent on the position of the CI nor the structure of the VMC, and is not tied to a specific topology. Thus, the proposed generalized method uniquely reveals the unifying theory underlying high step-up converters with any variation of SC/CI/VMC. In order to verify the theoretical analysis, many examples from the literature are investigated. Then, using design tips from the generalized method, a new high step-up converter is designed. A 150-W prototype of the converter shows 97.5% peak efficiency. The proposed converter also compares favorably to other topologies in both a power loss breakdown analysis and a component stress factor analysis.

Power-Loss Characterization and Reduction of the 750-V 100-KW 16-KHz Dual-Active-Bridge Converter With Buck and Boost Mode

This article presents an advanced method for power-loss breakdown of a high-power bidirectional isolated dual-active-bridge (DAB) dc-to-dc converter using SiC-<small>mosfet</small>/SBD H-bridge modules. This method is so simple and practical as to extract a switching loss from accurately measured overall losses. A test bench designed and built in this article is characterized by cascading the two identical 750-V 100-kW 16-kHz DAB converters equipped with the two identical unity-turns-ratio transformers. The test bench allows power-loss breakdown at buck and boost operation. When a dc-input voltage of 750&#x00A0;V is different from a dc-output voltage of 850&#x00A0;V at 100&#x00A0;kW and 16&#x00A0;kHz, &#x201C;hybrid&#x201D; phase-shift control makes the overall power loss lower by 158&#x00A0;W than &#x201C;pure&#x201D; phase-shift control.

Multiphase Direct AC Wireless Power Transfer System: Comparative Proposals Using Frequency and Amplitude Modulations

Using multiload wireless power transfer (WPT) systems to supply power to multiple receivers with a single transmitter is an interesting topic. However, previous studies are all based on a dc–dc WPT system. If the loads demand ac power, additional dc–ac inverters need to be implemented, which increases the system complexity and cost. This article addresses two direct ac WPT systems that can regulate the ac power of multiple phases or loads independently, using frequency modulation and amplitude modulation (AM), respectively. The proposed WPT systems can directly control the ac power of multiple loads through the transmitter side, without any power converter at the receiver side. A typical application of the proposed system is for powering a three-phase load in a rotational object, e.g., three-phase motors in articulated robots or in-wheel motors. To demonstrate the feasibility of the proposed WPT systems, simulation and experiment studies of a wireless three-phase power transfer are presented. The results suggest that AM is a more advantageous solution to a direct ac WPT system. A power-loss breakdown analysis is presented to suggest future steps of efficiency improvement.

A Comparative Study of Switched-Tank Converter and Cascaded Voltage Divider for 48-V Data Center Application

This paper presents a comparative study of the switched-tank converter (STC) and the cascaded voltage divider (CVD). The operating principles of the STC and the CVD with four times input-to-output conversion ratio ($4\times$ ) are discussed. Two design approaches of the CVD are considered, including the high-density CVD (CVD-HD) and the high-efficiency low-density CVD (CVD-LD). The power loss breakdown analysis and system efficiency evaluation are provided for both converters. From these results, it is found that the STC is more efficient and smaller in size than the CVD converter. Gallium nitride (GaN)-based hardware prototypes of both converters are built and tested. The $4\times $ -STC can achieve ~1500-W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density and 98.79% efficiency. The $4\times $ -CVD-LD can achieve 1061-W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density and 98.41% efficiency. Therefore, the $4\times $ -STC has 41% higher power density and 24% less power loss than the $4\times $ -CVD-LD.

Optimization of High-Density and High-Efficiency Switched-Tank Converter for Data Center Applications

In this paper, the design methodology of switched-tank converter (STC) is presented. The power loss breakdown analysis is conducted to point out the directions and paths for components optimization. It is revealed that the switching device conduction loss, printed circuit board (PCB) loss, and inductor loss become significant when output power is >150 W. Power loss of four switches is calculated and compared for switching device selection. The resonant capacitor is carefully designed to meet both current stress and ripple requirements. On the other hand, optimal design of the resonant inductors and PCB layout are fully investigated. The core loss model is provided, and different core materials are compared to minimize the core loss. Besides, a fine-tuned inductor winding structure is designed to achieve the lowest winding loss. Furthermore, PCB layout is optimized to get short loop length for each operation state. In addition to the hardware level optimization, an improved control method is proposed, in which the conduction time of switching devices is tuned to mitigate the circulating power. To verify the optimization work, a prototype of STC is built and tested. The experimental results indicate that a state-of-the-art performance of 98.71% efficiency and a 1000 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> high power density is achieved.

Comparative Analysis of Semiconductor Power Losses of Galvanically Isolated Quasi-Z-Source and Full-Bridge Boost DC-DC Converters

Abstract This paper compares semiconductor losses of the galvanically isolated quasi-Z-source converter and full-bridge boost DC-DC converter with active clamping circuit. Operation principle of both converters is described. Short design guidelines are provided as well. Results of steady state analysis are used to calculate semiconductor power losses for both converters. Analytical expressions are derived for all types of semiconductor power losses present in these converters. The theoretical results were verified by means of numerical simulation performed in the PSIM simulation software. Its add-on module “Thermal module” was used to estimate semiconductor power losses using the datasheet parameters of the selected semiconductor devices. Results of calculations and simulation study were obtained for four operating points with different input voltage and constant input current to compare performance of the converters in renewable applications, like photovoltaic, where input voltage and power can vary significantly. Power loss breakdown is detailed and its dependence on the converter output power is analyzed. Recommendations are given for the use of the converter topologies in applications with low input voltage and relatively high input current.

Power-Loss Breakdown of a 750-V 100-kW 20-kHz Bidirectional Isolated DC–DC Converter Using SiC-MOSFET/SBD Dual Modules

This paper describes the design, construction, and testing of a 750-V 100-kW 20-kHz bidirectional isolated dual-active-bridge dc-dc converter using four 1.2-kV 400-A SiC-MOSFET/SBD dual modules. The maximum conversion efficiency from the dc-input to the dc-output terminals is accurately measured to be as high as 98.7% at 42-kW operation. The overall power loss at the rated-power (100 kW) operation, excluding the gate-drive and control circuit losses, is divided into the conduction and switching losses produced by the SiC modules, the iron and copper losses due to magnetic devices, and the other unknown loss. The power-loss breakdown concludes that the sum of the conduction and switching losses is about 60% of the overall power loss and that the conduction loss is nearly equal to the switching loss at the 100-kW and 20-kHz operation.