Pfc With Digital Approach; Figure 2. Scheme Of Ac To Dc Boost Converter Topology; Figure 3. Ac To Dc Boost Converter Signals With Ccm Pfc - Output Vdc, Input Vac And Inductor Current (Time Scale = 5 Ms); Figure 4. Ac To Dc Boost Converter Signals With Ccm Pfc - Inductor Current And Power Mosfet Gate Command (Time Scale = 10 Μs) - ST STM32F103ZE User Manual

UM0877
Figure 2.
Figure 3. AC to DC boost converter signals
with CCM PFC - output VDC, input
Vac and inductor current
(time scale = 5 ms)
2.2

PFC with digital approach

● A digital implementation for a PFC gives some advantages.
– Easy implementation of sophisticated control algorithms.
– Quick software modifications to meet specific requirements.
– Simple integration with other applications.
From a theoretical point of view, it could be possible to replace an existing analog solution
made up of discrete components with ST's digital solution, in which case, other than the
PFC control, the same MCU would also manage the main application.
To perform a digital power factor corrector, a microcontroller needs to have information
about three main system parameters. These are the output DC voltage, the input AC voltage
and the inductor current.
These parameters, appropriately scaled down, are managed by the microcontroller that
modulates the switching of the MOSFET to have the input current in phase with the input AC
voltage while keeping the output DC voltage to a fixed and stable value.
A generic implementation scheme for a digital PFC is shown in
www.BDTIC.com/ST
Scheme of AC to DC boost converter topology
Doc ID 16854 Rev 1
PFC basics and operating principles
Figure 4. AC to DC boost converter signals
with CCM PFC - inductor current
and power MOSFET gate command
(time scale = 10 µs)
Figure 5.
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