Abstract:
Harmonic pollution has become a serious problem in power systems due to
non linear loads connected to the utility line. The injected harmonics can
result in a low power factor and various other problems such as: voltage
distortion, heating of transformers and reduction of system efficiency etc. In
order to prevent harmonic currents from entering the utility system,
corrective measures (e.g. active filtering) can be adopted within the power
electronic converter that would result almost sinusoidal currents at nearly
unity power factor. In this work, a single phase full bridge rectifier will
supply the dc input for a high frequency resonant inverter from the utility 50
Hz ac supply. The inverter will be switched so as to produce an output with
40 kHz frequency. In between the rectifier inverter stage a Boost
configuration active filtering scheme has been used to improve the power
factor and to make the input ac current wave-shape nearly sinusoidal. Input
current and power factor improvement using boost rectifier is common for
ordinary passive loads. In this thesis, the rectifier output do not directly feed
the load, rather it has another conversion stage in the form of a resonant
inverter. So, the rectifier load is an inverter and passive element
combination. Hence, the design and implementation of boost rectifier
filtering technique is different from the reported works. In the resonant
inverter, the load and rest of the series element in the circuit have to be
resonating. The complete circuit has been studied by simulation in this work
so as to obtain the design procedures of a boost rectifier filter for a resonant
inverter load to a rectifier. The study provides an alternative for passive
filters for input current shaping of rectifier - resonant inverter circuit
together with improved input power factor.
