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Isolated DC-DC Converters
Published in Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee, and Digital Control, 2017
Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee
The forward converter is also a single-switch isolated topology. This is based on the buck converter. In contrast to the flyback, the forward converter has a true transformer action, where energy is transferred directly to the output through the inductor during the transistor on time. When the transistor turns off, the secondary voltage reverses, D1 goes from conducting to blocking mode, and the freewheel diode D2 then becomes forward biased and provides a path for the inductor current to continue to flow. This allows the energy stored in L to be released into the load during the transistor off time.
Power Converters with Transformer Isolation
Published in Yim-Shu Lee, Computer-Aided Analysis and Design of Switch-Mode Power Supplies, 2017
The power converter circuits to be studied in this chapter include the following types: forward, flyback, Ćuk, electronic transformers, transformer-coupled push-pull, half-bridge, and full-bridge. Note that a forward converter is a buck converter with an isolation transformer and that a flyback converter is a buck-boost converter with an isolation transformer.
An Isolated PFC Zeta-forward Single-stage Single-switch for LED Driver Without Electrolytic Capacitor
Published in Electric Power Components and Systems, 2020
Amir Bagheran, Mohammad Rouhollah Yazdani
Also, in the forward converter by writing the volt-second balance for the transformer primary inductor (Lp) of the forward converter, the following equation is derived where N1 and N2 are the primary and secondary turns of the transformer, respectively, and Vo is the voltage drop across the LEDs. Due to the Eq. (35), the forward converter has to be operated in DCM for satisfying the circuit operation principles. The voltage gain of the proposed zeta-forward converter in DCM is given by Eq. (36) using Eqs. (34) and (35),
An improved isolated DC–DC Buck converter with high step-down ratio
Published in International Journal of Electronics, 2022
Hadi Mohebalizadeh, Ebrahim Babaei, Mehran Sabahi, Leila Mohammadian
Compared with non-isolated step-down topologies, the high step-down is obtained through the dc–dc flyback converter, forward structure, half-bridge, and full-bridge converters. The flyback dc–dc topology along with an air gap will lead to higher voltage stress on the involved switch. This requires the addition of a more snubber circuit such as an active clamped circuit. Meanwhile, these added elements increase losses, reduce efficiency, and increase the overall cost and circuit complexity. The number of a utilised circuit elements in the forward converter is more than the flyback converter. As a result, the overall cost of the forward converter is higher than the flyback converter. Forward converters can enhance efficiency using proposing different reset circuits (Kim et al., 2017). A new topology based on a hybrid full-bridge and LLC converter is presented. This topology has some features such as low circulation current loss and wide ZVS. To extend the ZVS range of lagging-leg power switches from zero to full load, a half-bridge should be added to the lagging-leg power switches (Lin & Chu, 2016). Also, an active method has been provided to enhance the overall efficiency of the proposed structure by using parasitic resonance energy recovery and regulating the voltage stress on the involved schottky diodes (Choi et al., 2016). A fast switch short circuit fault assessment strategy is suggested for the phase-shifted full-bridge converter. By combining the switching gate pulses and real-time index, the switch short-circuit fault (SFC) can be realised fast. Moreover, to keep the continuous operation mode of the system a remedial performance for the faulty phase-shifted full-bridge converter is presented in (Pei et al., 2015).
Overview of High-Step-Up DC–DC Converters for Renewable Energy Sources
Published in IETE Technical Review, 2018
Subhransu Padhee, Umesh Chandra Pati, Kamalakanta Mahapatra
Some of the basic isolated converter topologies are flyback converter, forward converter, push–pull converter, half-bridge converter and full-bridge converter. These converters are widely used for low power applications and consumer electronics [69]. But the main limitation of such topologies are poor transformer utilization factor, transformer saturation, bulky transformer, and large filter elements. Table 4 summarizes the features of different classical isolated DC–DC converter topology.