DESIGN AND SIMULATION OF PROTECTION TECHNIQUES IN SWITCHED MODE POWER SUPPLY CIRCUIT

Power supply is important to provide sufficient and stable power needed by the load. In order to provide power with high reliability, it is important to maintain the stability of the operation. Therefore, the internal circuitry of the power supply should be included with a protection system. In this project, overvoltage, overcurrent and switching protection will be installed in AC-to-DC Switched Mode Power Supply (SMPS). The SMPS is developed by combining a 3-phase full-bridge rectifier with a flyback converter. The multiple outputs isolated SMPS topology can be obtained by using three sets of transformer’s secondary winding. To improve the power efficiency and reduce the switching losses, zero current switching (ZCS) and zero voltage switching (ZVS) circuit will be implemented at the controlling switch of the converter. The crowbar circuit will be used to protect the circuits from overvoltage whilst for overcurrent, a sensor will be used to sense the overcurrent having a high resistance path to limit the current. It is found that by applying the overvoltage protection, the voltage that exceeds 240 V can be reduced to around 12 V.