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Electro-Optical Scanners
Published in Gerald F. Marshall, Glenn E. Stutz, Handbook of Optical and Laser Scanning, 2018
Timothy K. Deis, Daniel D. Stancil, Carl E. Conti
The basic operation of a flyback converter is that when the FET is turned ON, current ramps up at a rate di/dt = (Vdc)/Lpm, where Lpm is the magnetizing inductance of the primary winding of transformer Tl. When the FET is subsequently turned off the current has ramped to the Ipk = (Vdc)*Ton/Lpm thus storing the energy E = Lpm*(Ipk)22. With the FET turned OFF, the magnetizing inductance causes an instantaneous reversal in polarities of all windings’ voltages and the primary current transfers to the secondary as Is = Ipk (Np/Nm) where Np and Nm are the primary and secondary winding count. Using a higher voltage primary Vdc can help minimize transformer size and keep the Ipk to manageable levels. Also, one can employ multiple winding outputs to increase output voltage as needed or to select one of multiple output levels.
Off-the-Line Switching Power Supplies
Published in Nihal Kularatna, DC Power Supplies Power Management and Surge Protection for Power Electronic Systems, 2018
The transformer cores for flyback circuits require an air gap in the core so that they do not saturate from the DC current flowing in their windings. As mentioned above, the tape-wound core and ferrite core can both be provided with air gaps. The toroidal permalloy powder core is also used because it offers a distributed-type air gap. The frequency of the unit will dictate the selection of either tape-wound cores or ferrites as described previously, while the powder cores will operate at frequencies up to 50 kHz. Operation of the flyback converter is based on the storage of energy in the core and its air gap during the on time of the switch and discharging the energy into the load during the switch’s off time. The magnetic core operates in one quadrant of its B-H curve. For high-energy transfer in a small volume, the core should have the B-H curve shown in Figure 7.9. An ideal core has a large available flux swing (ΔB), low core losses, relatively low effective permeability, and low cost. MPP cores, gapped ferrites, Kool Mµ, and powdered iron cores are used in this application.
Lighting
Published in Dorin O. Neacşu, Automotive Power Systems, 2020
First, a flyback converter (Figure 7.11a) is used for the dc/dc converter from an automotive battery to a higher regulated dc voltage bus, usually up to 300 Vdc. This dc voltage is used with a full-bridge inverter for dc/ac conversion. The full-bridge inverter (Figure 7.11b) produces a 300–400 Hz square-wave voltage. During the steady-state production of ac square-wave voltage, it needs to supply ~35 W for the lamp.
High-Efficiency Boost-Flyback Converter with Voltage Multiplier Cells for High Voltage Gain Application
Published in Electric Power Components and Systems, 2018
António Manuel Santos Spencer Andrade, Everson Mattos, Mário Lúcio da Silva Martins
In the literature, the standard non-isolated step-up converter is the Boost topology. Theoretically, the Boost converter static voltage gain (M) can achieve approximately infinite when duty cycle approaches the unity. Nevertheless, in practice, due to the intrinsic resistance, the M is limited [8]. In concern to the isolated converter, the Flyback converter has been an attractive topology, due to it comply with the application requirements, high voltage step-up, low volume, high reliability. On the other hand, there are some drawbacks such as switching losses of the switch; reverse-recovery losses of the diodes; high turn ratio of the coupled inductor increasing the leakage inductance, which deteriorates the system efficiency [9]–[11]. To overcome these disadvantages, many techniques are proposed in the literature. Basically, these techniques can be presented in three groups: with transformer (isolated) [12]–[22]; association of PWM converter (stacked, cascade) [23]–[28]; and voltage cells multiplier [29]–[38].
Improvement of energy harvesting capability in grid-connected photovoltaic micro-inverters
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Özgür Çelik, Adnan Tan, Mustafa Inci, Ahmet Teke
A two-stage conversion scheme is selected to construct MI as shown in Figure 2. The selected circuit topology comprises a flyback converter operating in discontinuous conduction mode (DCM) with the D-NPC inverter. In the dc-dc stage, a flyback converter is utilized to perform MPPT operation and increase the input voltage. The energy from the PV module (260 W @ 35 V) is delivered to the dc-ac stage at a higher voltage value with minimized losses by the flyback converter. The flyback converter uses a high-frequency power switch, a high-frequency transformer, and a secondary fast recovery diode.
A hybrid PV/utility powered irrigation water pumping system for rural agricultural areas
Published in Cogent Engineering, 2018
A flyback converter is used for implementing MPPT. The flyback converter is derived from the buck–boost converter and provides isolation between input and output voltage. The turn ratio of the transformer provides increased design flexibility in the transfer relationship. A 500-W PV panel is used as the input of the converter. The transformer equivalent circuit that includes the magnetizing inductance is shown in Figure 3 (Hart, 2011).