Design and Construction of a Low-Cost Automatic Single-Phase Transfer Switch

Irregular power supply poses a serious problem in many developing countries with power outage usually experienced on a regular basis. Thus, this challenge necessitates the need for an automated method of power change over to an alternative source during power failure that will be an improvement over the manual change over system. This study aims to design and construct a microcontroller-based Automatic Transfer Switch (ATS) for a single-phase system. Atmega8 microcontroller was programmed to automatically switch power supply between a primary source and a secondary power source through the aid of relays. A modular approach was used in the design of this ATS, which incorporates Atmega8 microcontroller, diodes, resistors, L7805 voltage regulator, PC817 optocouplers, a buzzer alarm, NPN transistors, and a Liquid Crystal Display (LCD) that indicates which power source was available. This design is limited to 30A on full loading due to the power relay used in the design. The testing showed that the design was able to automatically switch power between two supply sources with no external aid and it performed optimally even when loaded to 90% of its maximum bearing-capacity.Keywords: Automatic Transfer Switch, Atmega8 Microcontroller, Liquid Crystal Display, NPN Transistors, PC817 Optocouplers, Relays

A Power Loss Decrease Method Based on Finite Set Model Predictive Control for a Motor Emulator with Reduced Switch Count

This paper presents a power loss decrease method based on finite set model predictive control (FSMPC) with delay compensation for a motor emulator with reduced switch count. Specifically, the topology and mathematical model of the proposed motor emulator with reduced switch count are firstly built. Secondly, in light of given instructions, the normal or fault reference current of the motor emulator is set by a reference current setter. Then delay compensation is applied for the predictive current model to calculate the current residual generated by each switch control signal, and the current tracking performance under actions of two adjacent switch control signals is evaluated for each sector. Finally, a switch power loss objective function is defined, then the two adjacent switch control signals that generate the lowest switch power loss are selected for the next second instant, which minimizes the power loss of the motor emulator with ensuring satisfied current tracking performance. Simulation and experimental results show the feasibility and effectiveness of the proposed method.