Abstract:
DC-DC converters are used in DC micro grids for different applications. As the output voltage of most of renewable energy sources is very low, DC-DC converters are used to step up the voltage. Various topologies of DC-DC converters are used for this purpose. Boost, buck-boost and cuk converter are the famous among them. The inability to achieve high voltage gain is one of the issues with the conventional converters. Their efficiency drops down significantly at high duty ratios. New topologies of converters are developed which can achieve high voltage gain with good efficiency. Non isolated high gain (NIHG) DC-DC converter is one of them which is proposed recently. It has high voltage gain and also has the advantage of comparatively low voltage stresses on switches. These advantages make this converter suitable for the applications of DC micro grids. However, the design of an effective controller is required to use this converter in DC micro grids. Previously no work has been done on the design of controller for this specific converter. The main contribution of this work is the design and performance analysis of different controllers for NIHG converter. State space average (SSA) equations of NIHG converter are derived. They are used to find the gains of the PID controller. Fuzzy controller is also designed for the same converter. PID and fuzzy controllers are connected to adjust the duty ratio of the converter’s switches to regulate the output voltage. PID and fuzzy controlled NIHG converter is exposed to different operating conditions i.e. input voltage variations, load variations, reference voltage variations. The performance of PID and fuzzy controllers are compared in terms of their transient response and the ability to adapt to different operating conditions. It is concluded that the PID controller has fast response time but it is well behind fuzzy controller in performance when large changes in load are applied. Fuzzy controller was able to reduce the overshoot in most cases. Fuzzy controller also showed good performance when large changes in load were applied. Therefore, it is proposed that fuzzy controlled NIHG converter can be a good choice to use in DC micro grids.
