Alceu Andre Badin

Unity Power Factor Isolated Three-Phase Rectifier With Split DC-Bus Based on the Scott Transformer

In this work, the three-phase rectifier with a new connection is presented. The use of the Scott transformer makes a split DC-bus voltage possible and the rectifier operates with unity power factor. Using only two active switches, the rectifier is able to generate symmetrical currents in the line and a balanced split DC-bus output voltage, which is necessary in several applications. Pulse width modulation and instantaneous average current control are used. There are two voltage controls that regulate the output voltage and the split DC-bus voltage. Complete simulation results under closed loop operation are given, as well as results of an experimental setup.

Unity Power Factor Isolated Three-Phase Rectifier With Two Single-Phase Buck Rectifiers Based on the Scott Transformer

This paper proposes an isolated three-phase rectifier power-factor correction using two single-phase buck preregulators in continuous conduction mode. The use of the Scott transformer renders a simple and robust rectifier to operate with unity power factor. With only two active switches, the rectifier is able to generate symmetrical currents in the line and a regulated voltage output without any necessary synchronous switches. The proposed control technique with sinusoidal pulse width modulation uses a feedforward of the output inductor current and only one voltage control regulates the output. Complete simulation results under closed-loop operation are given and a 12-kW prototype has been implemented in the laboratory, which demonstrated to operate successfully with excellent performance, and thus can feasibly be implemented in higher power applications.

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%.

High power factor three-phase rectifier with two interleaved single-phase buck rectifier

In this work, a unity power factor isolated three-phase buck rectifier is proposed. Based on the Scott transformer and using a two interleaved single-phase Buck pre-regulator in continuous conduction mode (CCM), this rectifier is simple and it has the capability to obtain low output voltage. With only two active switches with same reference, only one freewheel diode, the rectifier is able to generate symmetrical currents in the line and a regulated voltage output. The modulation is used conventional SPWM. The control has only one voltage control loop. Theoretical analysis, design procedure, complete simulation results with closed loop operation are given and a 6-kW prototype has been implemented in the laboratory which demonstrated to operate successfully with excellent performance.

Three-phase series-buck rectifier with split DC-bus based on the Scott transformer

In this paper, a new unity power factor isolated three-phase buck rectifier is presented. Based on the Scott transformer, this rectifier is simple and it has the capability to obtain low output voltage. Besides, it protects against short circuit and it needs no auxiliary circuit for inrush current. Using only two active switches, it is able to generate symmetrical currents in the line and output voltage regulated. The modulation is used conventional SPWM. The control has only one voltage control loop. Theoretical analysis, design procedure, complete simulation results with closed loop operation are given, as well as results of an experimental verification.

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.

An isolated three-phase power-factor correction rectifier using an autotransformer and two single-phase single-stage rectifiers

This paper presents an isolated three-phase power-factor correction rectifier using a Scott autotransformer and using two single-phase single-stage (S2) isolated current rectifiers with power factor correction, based on a Full-Bridge Flyback converter. The Scott autotransformer provides a phase reduction allowing the use of two single-phase rectifiers. The proposed converter can operate as a step-down or a step-up voltage, according to the input and output voltage levels. This paper presents the theoretical analysis of the converter for continuous conduction mode (CCM) as well as experimental results based on a 4 kW prototype.

A three-phase power-factor correction scheme using an autotransformer and two single-phase Buck rectifiers

This paper presents a three-phase unidirectional rectifier power-factor correction (PFC) using two modified single-phase Buck rectifiers in continuous conduction mode (CCM). The phase reduction technique using an autotransformer based on Scott Connection renders a non-isolated rectifier to operate with unity power factor. The power autotransformer is only 14% of the total output power. Two single-phase buck rectifier interleaved is able to regulate low voltage output. The control system is simple and it has only one voltage control loop. Theoretical analysis, design procedure, complete simulation results with closed loop operation are given and a 4-kW prototype has been implemented in the laboratory which demonstrated to operate successfully with excellent performance.