dc.contributor.author	Mohd Noh, Mohamad Affan
dc.date.accessioned	2023-12-13T07:51:08Z
dc.date.available	2023-12-13T07:51:08Z
dc.date.issued	2022
dc.description	Thesis (PhD. (Electrical Engineering))
dc.description.abstract	Single-phase alternating current to direct current (AC-DC) converters are widely used in industry and consumer products. Conventionally, the AC input is first rectified to obtain an unregulated DC voltage using a full-bridge rectifier. It is then followed by a power factor correction (PFC) circuit cascaded with another DC-DC converter with galvanic isolation. The utilization of these two converters are considered as two-stage conversion. However, there are reported work that simplifies the conversion of AC-DC to only a single-stage conversion using bridgeless circuits. Consequently, the total number of components will be reduced. Some circuit topologies are categorized as semi-bridgeless where the slow diodes in the circuit worsen the reverse recovery issue, which leads to conduction losses. Furthermore, the slow diode also contributed to crossover distortion at the input current, especially in certain applications that require high line input frequency. This work proposes an improved isolated bridgeless single-stage AC-DC converter. The proposed converter integrates the operation of a pure bridgeless PFC with an input boost inductor cascaded with a center-tap transformer and half-bridge circuit. In addition, it uses a bidirectional switch that can be driven with a single control signal. It is also proved that this boost half-bridge converter reduces the total number of components compared to the conventional circuit and semi-bridgeless circuit topologies. The circuit operation of the proposed circuit topology is then confirmed with the small-signal model, large-signal model, circuit simulation and then verified experimentally. It is designed and tested at 115 Vac, 50 Hz of input supply and 20 Vdc output voltage with a maximum output power of 100 W. It is verified that a high input power factor of 0.99 is achieved at full load both at the line frequency of 50 Hz and the 500 Hz of the input supply. In addition, the input current THD of 11.35% obtained experimentally meets the standard of IEC6000-3-2. The proposed circuit topology shows an improvement of 2.54% efficiency at full load as compared to the conventional circuit topology. In addition, the crossover distortion at the input current is minimized at high input line frequency.
dc.description.sponsorship	Faculty of Engineering - School of Electrical Engineering
dc.identifier.uri	http://openscience.utm.my/handle/123456789/903
dc.language.iso	en
dc.publisher	Universiti Teknologi Malaysia
dc.subject	Electric current converters
dc.subject	Electric power factor
dc.subject	Electric circuits—Testing
dc.title	Improved single-stage isolated bridgeless boost halfbridge ac-dc converter with bidirectional switch
dc.type	Thesis
dc.type	Dataset

Improved single-stage isolated bridgeless boost halfbridge ac-dc converter with bidirectional switch

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