طراحي و ساخت مبدل تركيبي سپيك-فوروارد با قابليت اصلاح ضريب توان تك‌مرحله‌اي براي منابع تغذيه كم‌توان

Design an‎d Construction of a SEPIC-Forward Hybrid Converter with Single-Stage Power Factor Correction(PFC) capability for Low-Power Power Supplies

مهندسي برق

In this research, a single-stage power factor correction structure has been designed, simulated, an‎d built to correct its performance an‎d integrate the output voltage regulation into one stage. Both converters use a common switch. The first converter is designed to be in discontinuous current mode an‎d inherently perform power factor correction. In the design of this converter, an attempt has been made to use the inductor with the smallest possible use. Therefore, a dumbbell core has been used. This prevents the inductor from saturating due to the presence of air flow in it. In the forward converter section, on the secondary side of the transformer, which is wound with EE3329 ferrite an‎d a ratio of 14 to 1, a diode bridge has been placed, which is used to reset the core. As a result, there is no need for a reset coil in the primary transformer. Also, the forward converter inductor has been eliminated an‎d the leakage inductor of the transformer plays its role. This structure has been built for a power design of about 50 watts. So that the voltage an‎d output current are designed to be 24 volts an‎d 2 amps, respectively. In order for the peak current of the first inductor at the input of the SPEC converter to be only with the voltage after the diode bridge an‎d its dependence on the output voltage to be negligible, the voltage in this switch is considered to be about two to three times the city power voltage, that is, about 800 volts. In this case, by adding a suitable LC filter in the input circuit, the input is obtained in a sinusoidal form. The switch current tension in this structure is about 2.5 to 3 amps. Also, a lossless snubber is used in these documents, which reduces losses an‎d improves efficiency. To change the duty cycle of the pulse gate, an op-amp oscillator circuit with a frequency of 50 kHz has been built. The shapes of different circuits have been simulated for a duty cycle of about 40 percent. Then, the operational results with laboratory equipment are ready. In this structure, the power factor (PF) is about 0.997 an‎d the total harmonic distortion (THD) is about 7 percent.

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احسان اديب

161061