STEVAL-ISA147V3 500 W fully digital AC-DC power supply (D-SMPS) based on STM32F334C8 microcontroller

The STEVAL-ISA147V3 is a digital switch mode AC-DC converter consisting of two power stages: an input semi-bridgeless power factor corrector (SBPFC) controlled by an STM32F051K8, and a regulation stage implemented with an LLC half bridge with synchronous rectification (SR), controlled by an STM32F334C8 microcontroller.

This 500 W AC-DC converter uses the so-called bridgeless PFC topology, with the advantage of lower conduction losses and higher efficiency by eliminating the need for a diode rectifier stage. This choice also allows a reduced component count compared to a standard PFC.

The input stage is typically controlled using an outer voltage loop for bus voltage regulation and an inner control loop to shape the current according to a sinusoidal waveform. The outer loop adjusts the current reference in order to maintain a regulated bus voltage, independent of load or input voltage variations. The output isolation and regulation stage is implemented using a half-bridge LLC topology, operating with constant duty cycle and variable frequency control.