Reverse-recovery current reduction in a ZCS boost converter with saturable inductors using nanocrystalline core materials (original) (raw)
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ZCS interleaved boost converter with saturable inductors for reverse-recovery reduction
Conventional DC-DC step-up converters present problems of low efficiency and low power density because of: 1. High power losses caused by hard-switching and reverse-recovery phenomenon. 2. High conduction losses produced by large peak currents when the converter has to operate at a high duty cycle. 3. Bulky and heavy cooling systems needed to dissipate the semiconductors losses. And, 4. Big and heavy capacitors and inductors required for smoothing and decoupling. Therefore, a novel Zero-Current-Switching two-phase interleaved boost converter with saturable inductors for reverse-recovery reduction is proposed. This converter can reduce the switching losses in the semiconductors due to the effect of the saturable inductors. Moreover, downsizing of the inductors and the output capacitor can be achieved due to the interleaving technique and the use of saturable inductors. In addition, high step-up operation can be achieved due to the presence of tapped-inductors. In this paper, the circuit configuration and the operation principle of the proposed converter and the reverse-recovery reduction behavior are presented. Finally, the effectiveness of the proposed converter is experimentally validated with a 600W prototype where a recovery-reduction of 58% was achieved.
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Analysis of output capacitor voltage ripple of the three-phase transformer-linked boost converter
The techniques of interleaving phases and magnetic coupling in power converters are effective downsizing the capacitive components as well as the inductive components in certain configurations. These techniques help tackle the problem of large mass and volume in autonomous electric vehicles as the use of the transformer-linked method in interleaved converters facilitates the miniaturization of the inductor, the output capacitor and the cooling system. Consequently, the analysis of all the characteristics of each component in the converter should be taken into account. This study presents the analysis of the output capacitor voltage ripple in the three-phase interleaved boost converter with coupled inductor (Transformer-linked). In this paper, the operating principle of the three-phase interleaved boost converter with coupled inductor is presented, then the output voltage ripple analysis is conducted for each mode of the operating principle, and finally the voltage ripple analysis is validated by experimental tests of a 1kW prototype.
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Power losses and their consequences in the addition of storage cells have the negative effect of decreasing the power density and the efficiency in Electric Vehicles. For this reason, an efficiency optimization methodology is required to help reduce that problem. Specifically, in the power converters that interface the storage unit with the electric motors and their inverters, an efficiency optimization is essential to reduce the power losses and thereby downsize the cooling components and the storage unit. In this work, the topology under evaluation is the two-phase interleaved boost converter using different magnetic components such as coupled and non-coupled inductors, which are topologies known as effective for high power density applications. This paper presents a methodology that optimizes the efficiency of the chosen topologies through a complete power loss modeling of each component. Next generation components such as Super Junction Mosfets, GaN and SiC diodes and Mosfets are compared to obtain the most efficient and suitable material to be implemented to the topologies, especially to the converter with coupled-inductor. Moreover, a design procedure is proposed to integrate the loss model and the characteristics of the selected components as the base to obtain the objective function, which is later solved using analytical calculations. Finally, the optimization methodology is validated by experimental tests.
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Volume comparison of DC-DC converters for electric vehicles
One of the main problems in autonomous electric vehicles is the volume of the electrical systems, because bulky components carry additional mass and high cost to the total system. Consequently, Interleaving phases and magnetic coupling techniques have been reported as effective methods for increasing the power density of the DC-DC converters that interface the storage unit with the electric motor. However, there are several converter topologies that use these techniques. Therefore, a volume assessment of these topologies is required in order to have a complete understanding when an electric power train is designed. In this paper, a volume modeling methodology is introduced with the purpose of comparing four different DC-DC converter topologies: Single-Phase Boost, Two-Phase Interleaved with non-coupled inductor, Loosely Coupled Inductor (LCI) and Integrated Winding Coupled Inductor (IWCI). This analysis considers the volume of magnetic components, power devices (conventional and next-generation), cooling devices and capacitors. As a result, interleaving phases and magnetic coupling techniques were validated as effective to downsize power converters. In particular, it was found that LCI and IWCI converters offer lower volume in comparison with other topologies.
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High power density DC-DC converter for home energy management systems
Environmental issues related to global warming and resources dryness, increase the global concern for reducing the energy consumption using high efficiency and high power density systems. Therefore, home energy management systems (HEMS) deal with these problems by monitoring and controlling the power consumption of home electronics. However, expanding of human living space increases intense requirements to downsize electronic systems. In order to enhance HEMS and optimize the household living space, this paper shows the design and power loss analysis of a high power density DC-DC converter capable to achieve high efficiency with low weight and low volume components. This converter, developed for home electronics and electric vehicles, uses a novel magnetic coupling technique capable to reduce the size of magnetic components and of the converter itself. As a result, a 1 kW interleaved boost converter with integrated winding coupled inductors (IWCI) was designed and experimentally validated obtaining a volumetric power density of 145 cc/kW.
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Efficiency is one of the most important aspects to consider in the design of electric systems for mobility applications. In this study, the interface between the storage system and the inverter is considered. This interface is a step-up DC-DC converter aimed to boost the energy storage voltage to the inverter voltage. This paper introduces the analysis, design, and comparison of four topologies of the interleaved boost DC-DC converter evaluating the effect of magnetic coupling in multi-phase and modular circuits. Additionally, a novel idea of a four-phase coupled inductor is presented. These power DC-DC converters are designed in order to find the suitable arrangement with the best efficiency.
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Design of a four-phase interleaved boost circuit with closed-coupled inductors
In this paper, a novel magnetic structure suitable for boost converters is proposed. Multi-phase interleaved method using coupled-inductor has gained attention in electric powertrains for electric, hybrid and fuel cell vehicles in order to achieve high power density. In fact, a four-phase boost converter using coupled inductor is used in the drive system of the Honda CLARITY. In particular, magnetic coupling method is used in coupled inductors, Loosely-Coupled Inductors (LCI) and Closed-Coupled Inductors (CCI). This study is focused on these methods, especially using the CCI. This paper presents a design method of a closed-coupled inductors using generic cores for a four-phase interleaved boost converter. In addition a comparison between the proposed topology with other conventional non-coupled methods is carried out. Furthermore, the evaluation of miniaturization is studied. As a result, the proposed method can achieve a huge reduction in the core volume and mass.
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Efficiency optimization of a single-phase boost DC-DC converter for electric vehicle applications
One of the main problems in autonomous electric vehicles is the energy storage, because a high autonomy and high power condition demand large mass, big volume and high cost of the storage unit. Consequently, in order to avoid power losses and to downsize the storage unit and the electric systems, the electric power train in the vehicle must be as efficient as possible. This paper proposes a methodology to optimize the efficiency of a DC-DC converter that interface the storage unit with the motor's drive. In this way, with the purpose of increasing the efficiency, this methodology combines three techniques: 1) The use of low-loss components such as Si CoolMos, GaN and SiC diodes and Mosfets, and Multilayer Ceramic Capacitors, 2) a complete power loss analysis as a function of the switching frequency and a calculation method of core losses based on the approximation of Fourier Series, and 3) the Area Product Analysis of magnetic components. With this methodology, it is possible to achieve high efficiency and high power density, which is suitable for automotive applications. The methodology has been verified with a set of tests on a 1kW prototype. As a result of the proposed methodology, a power efficiency of 99% was experimentally obtained.
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Three-phase LLC resonant converter with integrated magnetics
Recently, Electric Vehicles (EVs) have required high power density and high efficiency systems in order to save energy and costs. Specifically, in the DC-DC converter that feeds the non-propulsive loads in these vehicles, where the output voltage is much lower than the one of the energy storage unit. Therefore, the output current becomes quite high, and the efficiency and power density are reduced due to the high current ratings. Furthermore, magnetic components usually are the biggest contributors to the mass and volume in these converters. This paper proposes a Three-phase LLC resonant converter with one integrated transformer where all the windings of the three independent transformers are installed into only one core. Using this technique, a high reduction in the core size and thereby an increment in the power density and a reduction of the production cost are obtained. In addition, this integrated transformer is intended to be applied in the novel Three-phase LLC resonant converter with Star connection that is expected to offer reduction of the imbalanced output current, which is produced by tolerances between the phase components. Finally, the proposed converter with the novel integrated transformer is discussed and evaluated from the experimental point of view. As a result, a 70% reduction in the mass of the magnetic cores was achieved.
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