Development of overload protection using current sensing feedback-control algorithm

Abstract

Traditional methods to protect devices from overload usually use either fuses or electric breakers. However, the system is forced to stop working due to a disconnected power supply when the overload occurs incidentally. This may cause an unexpected risk in some circumstances. To resolve this problem, an overload protection system using a current sensing feedback-control mechanism is proposed in this study. First, the load current can be sensed and measured using a Hall sensor. The detected signal is then sent to the control circuit for an appropriate control signal to be generated to control the action of the switching circuit. The frequency of the control signal is determined by the predefined limited current without considering the load size. Based on a Fourier series transform, the harmonics of the output voltage can be reduced using LC filters so that only the dc term still remains. As a result, the load current can be smoothly maintained all the time. The experimental results confirm that the proposed scheme can effectively control the output current over an expected range.