Eduardo Felix Ribeiro Romaneli

Voltage Multiplier Cells Applied to Non-Isolated DC–DC Converters

This paper introduces the use of the voltage multiplier technique applied to the classical non-isolated dc-dc converters in order to obtain high step-up static gain, reduction of the maximum switch voltage, zero current switching turn-on. The diodes reverse recovery current problem is minimized and the voltage multiplier also operates as a regenerative clamping circuit, reducing the problems with layout and the EMI generation. These characteristics allows the operation with high static again and high efficiency, making possible to design a compact circuit for applications where the isolation is not required. The operation principle, the design procedure and practical results obtained from the implemented prototypes are presented for the single-phase and multiphase dc-dc converters. A boost converter was tested with the single-phase technique, for an application requiring an output power of 100 W, operating with 12 V input voltage and 100 V output voltage, obtaining efficiency equal to 93%. The multiphase technique was tested with a boost interleaved converter operating with an output power equal to 400 W, 24 V input voltage and 400 V output voltage, obtaining efficiency equal to 95%.

A Modified SEPIC Converter for High-Power-Factor Rectifier and Universal Input Voltage Applications

A high-power-factor rectifier suitable for universal line base on a modified version of the single-ended primary inductance converter (SEPIC) is presented in this paper. The voltage multiplier technique is applied to the classical SEPIC circuit, obtaining new operation characteristics as low-switch-voltage operation and high static gain at low line voltage. The new configuration also allows the reduction of the losses associated to the diode reverse recovery current, and soft commutation is obtained with a simple regenerative snubber circuit. The operation analysis, design procedure, and experimental results obtained from a 650-W universal line power-factor-correction prototype of the proposed converter are presented. The theoretical analysis and experimental results obtained with the proposed structure are compared with the classical boost topology.

A Modified SEPIC Converter With High Static Gain for Renewable Applications

A high step-up DC-DC converter based on the modified SEPIC converter is presented in this paper. The proposed topology presents low switch voltage and high efficiency for low input voltage and high output voltage applications. Two alternatives with and without magnetic coupling are analyzed. The magnetic coupling allows to increase the static gain with a reduced switch voltage. The theoretical analysis and experimental results are presented. Two experimental prototypes were developed with an input voltage equal to 12 V and an output power equal to 100 W. The efficiency obtained with the prototype without magnetic coupling was equal to 91.2% with an output voltage equal to 120 V and nominal output power. Efficiency equal to 95% was obtained with the prototype with magnetic coupling operating with an output voltage equal to 240 V and nominal output power.

High-Power-Factor Rectifier Using the Modified SEPIC Converter Operating in Discontinuous Conduction Mode

The theoretical and experimental analysis of a modified version of the SEPIC dc-dc converter used as preregulator operating in discontinuous conduction mode (DCM) is presented in this paper. The proposed converter presents a low input current ripple operating in DCM, and the switch voltage is lower than the output voltage. The switch voltage reduction increases the converter reliability and a low drain-to-source on-resistance (RDSon) MOSFET can be used depending on the converter specification. Moreover, a digital control technique is applied to the proposed converter in order to reduce the third-harmonic input current distortion resultant of the operation in DCM. Finally, a 100-W prototype was developed operating with efficiency equal to 95.6%.

An Auxiliary Self-Oscillating Preheating System for Self-Oscillating Fluorescent Lamp Electronic Ballasts

The fluorescent lamp lifetime is very dependent of the start-up lamp conditions. The lamp filament current and temperature during warm-up and at steady-state operation are important to extend the life of a hot-cathode fluorescent lamp, and the preheating circuit is responsible for attending to the start-up lamp requirements. The usual solution for the preheating circuit used in self-oscillating electronic ballasts is simple and presents a low cost. However, the performance to extend the lamp lifetime is not the most effective. This paper presents an effective preheating circuit for self-oscillating electronic ballasts as an alternative to the usual solution.

Development of a new single phase high power factor rectifier with ZVS commutation and high frequency isolation

A new high-power-factor rectifier with high-frequency isolation is presented in this paper. The proposed topology presents intrinsic ZVS commutation allowing the operation with high-switching frequency. It also presents the multiphase operation reducing the input inductance and input current ripple. The structure is a bridgeless rectifier, reducing the number of semiconductors in conduction, presenting less conduction losses. The proposed structure is composed by a multiphase boost converter operating in CCM integrated with a ZVS DC-DC full-bridge converter without the output inductor and operating in DCM. The experimental results are obtained from a 2 kW prototype and switching frequency equal to 44 kHz, presenting efficiency equal to 91% at nominal power.

Distributed generation: Design and implementation of an AC module based on a current fed push-pull converter for connecting photovoltaic panels to electric grid

This project presents 100W AC Module based on current fed push-pull converter applied to photovoltaic modules. The main goal is to demonstrate the functionality of the chosen converter topology for implementation on low power distributed generation from photovoltaic panels on the integrated module configuration.

A soft-switching universal-input voltage HPF rectifier implemented with a modified sepic converter

A high-power-factor rectifier suitable for universal-line base on a modified version of the SEPIC converter is presented in this paper. The voltage multiplier technique is applied to the classical SEPIC circuit obtaining new operation characteristics as low switch voltage operation and high static gain at low line voltage. The new configuration also allows the reduction of the losses associated to the diode reverse recovery current and soft-commutation is obtained with a simple regenerative snubber circuit. The operation analysis, design procedure and experimental results obtained from a 650W universal-line high power factor prototype of the proposed converter are presented. The theoretical analysis and experimental results obtained with the proposed structure are compared with the classical boost topology.

A half-bridge doubler boost operating as AC-DC and DC-DC converter

This paper presents a voltage doubler AC-DC converter to be applied in UPS. It is capable of operation with AC and DC Input source. The proposed rectifler provides high power factor and improves power efficiency for line voltage applications. The conduction losses are reduced by essentially eliminating the full-bridge diode rectifier. A bidirectional switch is used for the power switches, simplifying the overall power circuit structure. The two output capacitor voltage imbalance is inherent in the half-bridge rectifier, and therefore the balance control technique will be added in the future to complete this research. The operational principles, design considerations, and realizations are discussed and verified. The rectifier is suitable especially for a half-bridged inverter that requires a dual power supply. The practicability of the proposed voltage-doubling rectifier is confirmed by simulation and experiment The specification of the proposed half-bridge doubler boost is rated at 230 W and operates at 20 kHz, with an input AC voltage of 127 VRMS or an input DC voltage of 144 VDC and a regulated output voltage of 480 VDC, for experiments to verify the theoretic analysis as a solution to the problem of a inexistent doubler boost converter with a common point between line source, DC source and load.

Design and implementation of a high efficiency AC-AC Buck converter

This paper presents an AC-AC Buck converter in which a modulation technique was applied in order to reduce losses due to dissipative snubbers. Theoretical analysis and numerical simulation were performed. A 100W prototype was built and tested. Efficiency curves show that snubber losses are minimized with the use of a simple open-loop control technique.