Variable Frequency Control of the Zero-Voltage Switching Two-Inductor Boost Converter

The two-inductor boost converter has been previously presented in a zero-voltage switching (ZVS) form where the transformer leakage inductance and the MOSFET output capacitance can be utilized as part of the resonant elements. In many applications, such as maximum power point tracking (MPPT) in grid interactive photovoltaic systems, the resonant converter is required to operate with variable input output voltage ratios. This paper studies the variable frequency control of the ZVS two-inductor boost converter to secure an adjustable output voltage range while maintaining resonant switching transitions. The design method of the resonant converter is thoroughly investigated and explicit control functions relating the circuit timing factors and the voltage gain for a 200 W converter are established. Three sets of theoretical, simulation and experimental waveforms are provided for specific operating points. A variation of the basic circuit, the resonant converter with a voltage clamp, which is capable of operating with a wider output voltage range but a lower switch voltage stress, is also given at the end of the pape

Isolated zero-voltage switching two-inductor boost converter with two coupled input inductors and one magnetic core

The isolated two-inductor boost converter with an auxiliary transformer has been previously proposed for applications where the low voltage inputs need to be transformed to high voltage outputs. In order to utilise the leakage inductance of the isolation transformer, the zero-voltage switching (ZVS) topology can be employed. However, a large component count exists in the resonant converter and this contributes to cost and size. In this paper, a new ZVS isolated two-inductor boost converter with two coupled input inductors and an integrated magnetic structure is proposed. In the proposed topology, the seven copper windings and the five magnetic cores required by the auxiliary transformer, the two input inductors, the resonant inductor and the isolation transformer in the discrete magnetic arrangement are integrated into one magnetic core with four copper windings. This paper establishes the inherent relationship between the integrated and the discrete magnetic implementations of the isolated ZVS two-inductor boost converter with two coupled input inductors through the switching state and magnetic circuit analyses. This significantly simplifies the analysis of the new converter with the magnetic integration by modelling the converter with its discrete magnetic equivalent. Finally, both the theoretical and the experimental waveforms of a 1 MHz 100 W converter are provided and they agree well with each other

An Analysis of a Voltage Clamped Zero-Voltage Switching Two-Inductor Boost Converter with a Wide Load Range

The Zero-Voltage Switching (ZVS) two-inductor boost converter has been previously developed for the dc-dc conversion stage in a photovoltaic (PV) Module Integrated Converter (MIC) and is able to operate with variable load condition under variable frequency control. However, the converter only offers a narrow output voltage range and this is limited by the MOSFET voltage stress. In this paper, a voltage clamped ZVS two-inductor boost converter is proposed. The converter is able to operate under a wide output voltage range with a lower MOSFET voltage stress while maintaining the resonant transitions. The state analyses of three different operation modes are provided. The design process is also demonstrated in detail and explicit control functions for a 200-W converter are established. Finally, a brief comparison of the advantages and the disadvantages of the two ZVS converters is provided

Analysis and Design of a Passive Lossless Snubber in the Two-Inductor Boost Converter with a Variable Input Voltage

This paper offers a detailed analysis of the non-dissipative snubbers for the hard-switched two-inductor boost converter fed from a sinusoidally modulated two-phase synchronous buck converter. The state analyses and the theoretical waveforms are provided for the three active operation modes of the snubber circuit. The set of border conditions in terms of the buck stage duty ratio for each operation mode is explicitly established. The experimental waveforms are also provided to validate the theoretical analysis

Učinski izmjenjivač visoke djelotvornosti s posebnim istosmjernim međukrugom

In case of medium voltage (several tens up to hundred volts on DC-side) solar inverter applications, a DC-to-DC converter for voltage level adaptation is required in series of the DC-to-AC inverter. This leads to a two-stage concept with accumulation of the losses. In our case a concept was chosen where the efficiency of each stage is maximized by using the best topology. The given requirements make the application of a non-isolated design imperative to avoid additional transformer losses. In this paper a 60V–120V DC (input) to 230V AC (output) / 1kW converter with minimal conversion losses is derived. A simple modification in the inverter\u27s output section leads to a significant improvement of the losses in the inverter system. Only three additional components (two diodes and one inductor) are necessary to optimize the inverter\u27s power stage. The topology presented here shows a remarkable improvement of the switching losses and significantly reduced EMC. It is well-suited for solar power inverter applications.U slučajevima srednjenaponskih razina ulaznog napona (nekoliko desetaka do stotinu volti na istosmjernoj strani) izmjenjivača napajanih iz fotonaponskih ćelija, zahtjeva se istosmjerni pretvarač spojen u seriju s izmjenjivačem, za prilagodbu naponskih razina. Takav dvostupanjski pristup uzrokuje povećanje gubitaka. U ovom je slučaju odabran pristup kod kojeg se djelotvornost svakog stupnja pretvorbe maksimizira uporabom najpovoljnije topologije. Zadani zahtjevi čine obveznom uporabu istosmjernog pretvarača bez galvanskog odvajanja, da bi se izbjegli dodatni gubici u transformatoru. U ovom članku izveden je pretvarač snage 1 kW, ulaznog istosmjernog napona 60 V–120 V, izlaznog izmjeničnog napona 230V, s minimalnim gubicima pretvorbe. Jednostavna prilagodba u izlaznom stupnju izmjenjivača dovodi do značajnog smanjenja gubitaka u izmjenjivaču. Za optimiranje izlaznog stupnja izmjenjivača potrebne su samo 3 dodatne komponente (2 diode i prigušnica). Ovdje prikazana topologija pokazuje značajno smanjenje sklopnih gubitaka i smanjuje elektromagnetske smetnje. Posebno je pogodna za primjenu kod izmjenjivača napajanih iz fotonaponskih ćelija

Programmable Topology Derivation and Analysis of Integrated Three-Port DC-DC Converters with Reduced Switches for Low-Cost Applications

© 1982-2012 IEEE. Thanks to the favorable advantage of low cost, integrated three-port dc-dc converters with reduced switches have attracted extensive attention. In order to provide more new topologies, this paper aims to propose a programmable topology derivation method, which effectively simplifies the cumbersome process of the conventional combination method. Instead of the manual connection and examination, the proposed alternative can quickly and rigorously derive multiple viable integrated three-port dc-dc topologies from a great number of possible connections with the aid of computer program. Besides, generalized analysis is also accomplished, with which performance characteristics of all derived converters are simultaneously obtained and then a comprehensive comparison can be easily conducted to select a preferred one for the practical application. Finally, an example-specific application with one input and two outputs is given, with topology selection, design, and experimental results demonstrated in detail

Power electronics and control of a four inputs hybrid power system

A hybrid power system consists of two or more power sources working in parallel. Such a system needs power electronics to extract maximum power and to control the flow of power from each renewable power source to the users load. We consider a small hybrid power system consisting of two wind turbines, a PV array and a pico-hydro system. A parallel combination of DC-DC converters connected between renewable energy sources and a common DC bus is used to control the power flow in the hybrid power system. In this paper we present a power electronic and control solution for such four inputs small hybrid power system with a common 48V DC bus. System power electronics design and proposed control strategies for each renewable power inputs are presented. Design and development progress of the proposed power electronics and control arrangement is included in the paper