High power adjustable switching power supply (SMPS) 3-60V 40A
High power adjustable switching power supply (SMPS) 3-60V 40A This switching power supply was built because I needed a powerfull adjustable bench power supply. Linear topology would be unusable for this power (2400W = 2.4 kilowatts!), so I chose a switching topology of a two switch forward (half-controlled bridge). In my article about SMPS's it is a topology II.D. The switching supply uses IGBT transistors and is controlled by UC3845 chip. The schematic of my switching power supply you can see below. Mains voltage goes first through an EMI interference filter. It is then rectified using a bridge rectifier and smoothed using capacitor C4. Due to high capacity, there's an inrush limiting circuit with Re1 relay contact and R2 resistor. Relay coil and fan (from an AT / ATX PC power supply) are powered from 12V, which is dropped from 17V aux supply using a resistor R1. Select R1 value so that the voltage at the relay coil and the fan was 12V. The auxiliary power supply circuit use