Feedback Loop Stabilisation and EMI Filter Design of A High Frequency Dc-Dc Converter For Solar Power Applications

This thesis aims at developing a technique for stabilising the feedback loop of a high-frequency DC / DC converter followed with design of an EMI filter. This type of dc-dc converters can be used in solar power system to obtain a stable output under varying input conditions. A DC/ DC converter consists of a Pulse modulated controller, MOSFET switches, switching transformers, rectifier , filter and output sensing mechanism for feedback control. Initially design of the power supply to meet the output voltage and current requirements was carried out. An analog controller UC-1825 is used for the PWM control of the converter circuitry. The converter circuit was implemented using a voltage fed push pull topology and is also provided with additional windings for control and telemetry. The switching frequency is kept at a high value so as to minimise the size of filter components. Then the circuit elements are linearized and test the stability of the system using frequency response analysis in MATLAB software. A type 2 compensator was identified and implemented in the circuit to achieve necessary phase margin, gain margin, and bandwidth. And finally an EMI filter was designed based on the obtained bandwidth. The overall stability of the system including the filter was analysed and step response plot was also checked to test the adequacy of the design. The overall system including input filter was simulated in MATLAB and the results are verified.