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|???metadata.dc.title???: ||A new unity power factor quasi-resonant induction heater|
|???metadata.dc.contributor.*???: ||Sazak, Bekir Sami|
|???metadata.dc.identifier.citation???: ||Sazak, B. S. (1997) A new unity power factor quasi-resonant induction heater. Unpublished PhD thesis. Univeristy of Glamorgan.|
|???metadata.dc.description.abstract???: ||This thesis reports an investigation into the design of converters for induction heating
systems based upon resonant switch mode power converter techniques.
The proposed three phase unity power factor induction heating system consists of two
stages of power conversions. The important requirements for each stage of the power
conversion of a typical induction heating system working from a three-phase supply are
identified. A wide range of power converters which fulfil these requirements are
compared and evaluated. From the evaluation, the most applicable converter topologies
are selected. Each selected converter class is investigated in great detail to outline their
advantages and disadvantages.
The first stage consists of a push-pull buck converter connected to a unity power factor
rectifier stage. This stage converts the three phase AC mains supply to a required DC
value. The second stage, which converters the DC into AC is a single ended resonant
Analysis of the converters has been made and the design procedure has been
formulated. The design procedure allows a strenuous design of each resonant converter
for particular converter applications.
The final converter design has been simulated using the circuit simulation software
packages Design Architect and Accusim to verify the results of analysis. The most
important design and construction achievements can be summarised as follows:
A novel push-pull buck quasi-resonant converter with a three-phase rectifier stage has
been built and tested. At its maximum operating frequency of 40kHz, the prototype
converter delivers an output power of 500W. The converter draws nearly sinusoidal
currents from the three-phase mains supply and has an input power factor approaching
A secondary stage resonant converter provides AC for the induction heater coil. This
AC current flowing in the induction coil creates an alternating electromagnetic field for
the workpiece. An induction heating coil has been designed and built by using electrical
equivalent coil design method.
A novel control strategy was developed to provide output power control. Both
converter and inverter stage of the system are operated in the zero-current switching
condition. The use of this technique allows higher switching frequencies and provides
low switching losses.
The full design details are presented along with simulation and practical results. The
simulation and practical performance results presented show good correlation with