Presented By: Alana Savage Supervisor: Dr Geoffrey Walker

1
2.4kW Unity Power Factor Rectifier
Presented By Alana Savage Supervisor
Dr Geoffrey Walker
What
How
Why

• PoWeR FaCToR (PF) is a measure of how
  effectively a load draws real power. It is the
  ratio of real power to apparent power.
• PF P/S I1/IS cos q where q is the angle
  between the voltage and the current, and I1 is
  the fundamental (50Hz sinusoidal) current
  component of the total RMS current IS.
• Ideally PF 1.0. Here, the voltage and current
  waveforms have the same shape, contain the same
  harmonic spectrum, and are in phase
• The rms current and voltage are minimised at
  unity power factor i.e. with a linear resistive
  load.
• PoWeR fAcToR coRrEcTioN (PFC) aims to make the
  input to the power supply look like a purely
  resistive device.

• The reduction of input current harmonics and
  improved PF operation are important requirements
  from the power quality point of view and
  especially when forthcoming harmonic standards,
  such as IEC-555-2, must be satisfied.
• PFC allows higher power densities and increased
  efficiencies.
• PFC is beneficial for industries such as
  medical, computer, military, and
  telecommunications.
• IEC 555-2(current at each harmonic)

• UPF rectifier that will convert an input of
  mains power (240VAC and 10A) to output a
  regulated 420VDC

• Conventional diode bridge rectifier input stage,
  followed by a boost converter used for current
  shaping the input current, so that it will be
  sinusoidal and in phase with the input voltage.
• Feedback is necessary to control input current
  implemented with UC3855 chip.
• ZeRo VoLtaGe TRaNsiTioN (ZVT) allows an
  improvement in efficiency over the traditional
  converter.