Active rectification

Voltage drop across a diode and a MOSFET. The low on-resistance property of a MOSFET reduces ohmic losses compared to the diode rectifier (below 32 A in this case), which exhibits a significant voltage drop even at very low current levels. Paralleling two MOSFETs (pink curve) reduces the losses further, whereas paralleling several diodes won't significantly reduce the forward-voltage drop.

Active rectification, or synchronous rectification, is a technique for improving the efficiency of rectification by replacing diodes with actively controlled switches, usually power MOSFETs or power bipolar junction transistors (BJT).[1] Whereas normal semiconductor diodes have a roughly fixed voltage drop of around 0.5 to 1 volts, active rectifiers behave as resistances, and can have arbitrarily low voltage drop.

Historically, vibrator-driven switches or motor-driven commutators have also been used for mechanical rectifiers and synchronous rectification.[2]

Active rectification has many applications. It is frequently used for arrays of photovoltaic panels to avoid reverse current flow that can cause overheating with partial shading while giving minimum power loss. It is also used in switched-mode power supplies (SMPS).[1]

  1. ^ a b Cite error: The named reference emadi was invoked but never defined (see the help page).
  2. ^ Maurice Agnus Oudin (1907). Standard polyphase apparatus and systems (5th ed.). Van Nostrand. p. 236. synchronous rectifier commutator.