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Title: Single-stage power factor correction converter topologies for low power off-line applications
Author: Lord, Edward Michael
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2004
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Since January 2001 it has been necessary for equipment connected to the low voltage public distribution network in Europe and Japan to comply with IEC 61000-3-2. The regulation IEC 61000-3-2 specifies the level of current that can be drawn for particular harmonics. Much equipment today is fitted with a Switch Mode Power Supply (SMPS) at its input to interface between the line voltage and internal low voltage electronics. This SMPS must not only convert the line voltage, but also ensure that the input current to the device meets the IEC regulations. To meet these regulations two methods are normally used, passive filtering using a large filter inductor or a boost converter cascaded with the main DC/DC SMPS converter with isolation. To try and reduce component count, cost and increase efficiency many new single-stage Power Factor Correction (PFC) topologies have been proposed. In a single-stage topology the output voltage regulation and meeting IEC 61000-3-2 are combined into a single power stage. Unfortunately very little is known about the behaviour or performance of these single-stage topologies. In this thesis two of the more promising single-stage topologies, the bi-forward and CS S2PFC converters are investigated further. A new topology using a low frequency switch (LFSPFC) is introduced. The topologies are analysed investigating input current shape and harmonic content, voltage variation on bulk capacitance and component stresses. Simulation in PSpice is used to confirm circuit operation. Four 150W output power experimental circuits were built: bi-forward converter, CS S2PFC converter, passive filtering cascaded with a forward converter and a boost pre-regulator cascaded with a forward converter. The converters operate from universal input voltage and have outputs at 5V and 12V. A 100W test circuit was built for the LFSPFC operating from 230V input voltage and with an output of 5V. Experimental results are presented showing circuit behaviour and performance of the bi-forward, CS S2PFC and LFSPFC converters. The bi-forward and CS S2PFC converters are compared to the passive filter and boost converter cascaded with a forward converter. It is demonstrated that neither of these single-stage topologies is at present a viable replacement for either present method, but the LFSPFC could be a lighter weight and less bulky alternative to passive filtering.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available