Two high static gain step-up dc-dc converters based on the modified SEPIC converter are presented in this paper. The proposed topologies present low switch voltage and high efficiency for low input voltage and high output voltage applications. The configurations with magnetic coupling and without magnetic coupling are presented and analyzed. The magnetic coupling allows the increase of the static gain maintaining a reduced switch voltage. The theoretical analysis and experimental results show that both structures are suitable for high static gain applications as a renewable power sources with low dc output voltage. Two experimental prototypes were developed with an input voltage equal to 15 V and an output power equal to 100 W. The efficiency at nominal power obtained with the prototype without magnetic coupling was equal to 91.9% with an output voltage of 150 V. The prototype with magnetic coupling operating with an output voltage equal to 300 V, presents an efficiency at nominal power equal to 92.2%.

The development of a high static gain dc-dc converter with the integration of the voltage multiplier cell and the coupled inductors operating with soft switching is presented in this paper. The use of coupled inductors and voltage multiplier techniques allow the operation with low switch voltage and low conduction losses. The switch turn-on commutation occurs with zero current switching due to the presence of the coupled-inductor leakage inductance. The leakage inductance also reduces the reverse recovery current of all diodes. The zero voltage switching at the power switch turn-off is obtained with the inclusion of only a diode and a snubber capacitor per phase, without the use of auxiliary switches. The soft-switching range is independent of the load and is maintained even with a light load. The theoretical analysis, design procedure, and experimental results are presented in this paper. A two-phase boost converter with one voltage multiplier and coupling inductors was built with an input voltage V _in = 24 V, output voltage V _o = 432 V, and output power P _o = 400 W. The efficiency obtained is equal to 94.55% at the nominal power.

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.

Power factor correction (PFC) rectifiers based on the classic boost topology have become widespread owing to their current input features, and can obtain optimal results in terms of power quality. However, several applications require an output dc voltage lower than the ac input voltage. In such cases, two-stage topologies provide lower voltage values at the output, which increases the number of components. Moreover, such topologies tend to incur higher losses and are costly. Therefore, a unidirectional hybrid single-stage single-phase PFC boost rectifier with a switched-capacitor cell and low voltage gain is proposed. Furthermore, the proposed topology has two active switches, and natural balance exists between the voltages of the capacitors. Therefore, an additional control system is not required. The proposed topology was theoretically analyzed and experimentally validated using a 1 kW prototype with two different operational situations: (A) 127 V ac and 100 Vdc; (B) 220 Vac and 200 Vdc, input and output voltages, respectively. The experimental results essentially reveal that the power factor is approximately one, and the total harmonic distortion of the input current is 4.6%. The maximum efficiency achieved was 96.5% in the operational situation (B).

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 (RDS _on ) 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 density, efficiency, control simplification, and robustness are highly demanded for power factor correction (PFC) converters. This paper proposes a totem-pole rectifier based on the switching cell with switching frequency modulation (SC-SFM). The SC-SFM features interleaved operation, soft commutation, and resistive characteristics with continuous conduction in the input inductor. The converter operates without needing sensors and a control loop for the current. Unlike conventional solutions or some sensorless converters, the converter does not require a fast control loop to shape the current since the current naturally follows the input voltage. Only one output voltage sensor and one input half-line cycle detector are required to achieve unitary power factor and regulated DC output voltage. A detailed analysis of the converter operation, including the operating principle, mathematical analysis, a small signal model, and control method, is presented, including the differences in operation from the conventional PFC rectifier with the diode bridge. Experimental results evaluate a 1-kW prototype with different switch technologies (IGBT, SiC, and GaN).