STEVAL-ISF002V1 STMicroelectronics, STEVAL-ISF002V1 Datasheet - Page 8

• Manufacturer Part Number: STEVAL-ISF002V1
• Description: BOARD EVALUATION
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ISF002V1

• Main Purpose: *
• Embedded: *
• Utilized Ic / Part: *
• Primary Attributes: *
• Secondary Attributes: *
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-10422

PFC basics and operating principles
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PFC basics and operating principles
Introduction
Most of the power conversion applications consist of an AC to DC conversion stage
immediately following the AC source. The DC output obtained after rectification is
subsequently used for further stages.
Since many applications demand a DC voltage source, a rectifier with a capacitive filter is
necessary. However, current pulses with high peak amplitudes are drawn from a rectified
voltage source with sine wave input and capacitive filtering. The current drawn is
discontinuous and of a short duration irrespective of the load connected to the system.
When this type of current is drawn from the mains supply, the resulting network losses, the
total harmonic content and the radiated emissions become significantly higher. At power
levels of more than 500 W, these problems become more pronounced.
Figure 1.
Two factors that provide a quantitative measure of the power quality in an electrical system
are the power factor (PF) and total harmonic distortion (THD). The amount of useful power
being consumed by an electrical system is predominantly decided by the PF of the system.
●
Most often, the core of a power factor correction (PFC) is an AC to DC boost converter (see
Figure
modulated so that the inductor current is in continuous conduction mode (CCM), as shown
in
Figure
Benefits from improvement of power factor include:
–
–
–
–
2). For power typically above 600 W, the switching of the power MOSFET (T) is
3.
lower energy and distribution costs,
reduced losses in the electrical system during distribution,
better voltage regulation,
increased capacity to serve power requirements.
Typical AC to DC rectification without PFC
Doc ID 16854 Rev 1
UM0877