An Efficient Approach to Design Switch Mode Power Supply for LED Lamp

This paper presents the multistage switch mode power supply for LED lamp with output power of 98W and possesses 95 % efficiency. Proposed scheme for switch mode power supply has designed using forward converter satureable transformer. In this topology three stages are used to optimize the power, first stage is AC to DC rectification, second is DC to DC conversion in which forward converter has used to step down the voltage at specific level. This converter operates in the 36 KHz frequency which allows to reduce the size of passive elements i.e. capacitors, transformers and inductors, and third stage is filtration. Half wave rectifier is connected at the secondary side of the transformer. The half wave rectifier provides dc output, which is directly connected to the string of LEDs, and desired voltages are obtained across LED lamp. All the dynamics in these stages are in the form of closed loop to implement a suitable controller in LABVIEW. The overall topology is controlled by using PID controller. The converter regulates the current of LEDs by using constant current feedback circuit. As LEDs current is nonlinear so we must have to regulate current rather than voltage. Proposed scheme does not need any input voltage feedback or input current sensing devices. THD in voltage has been reduced to 2% at main AC lines and overall efficiency of proposed scheme is 95%. PCB layout of proposed scheme and experimental simulations has been done on NI MULTISIM