Zeta converter

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In electronics, a zeta converter is a form of DC voltage converter that can convert a positive DC voltage supplied into either a higher or lower positive DC output voltage. This converter is used in power supply modules for electronic circuits. Adapted Zeta converter types with galvanic isolation are used in switched-mode power supplies for active reactive power compensation .

General

Circuit diagram of a Zeta converter

Functionally, this converter topology, as sketched on the right, has a similar structure to the related SEPIC converter . However, it offers the advantage of an approximately constant output direct current due to the output-side coil L 2 , so that the output capacitor C 2 only has to be dimensioned for a smaller ripple current or the output voltage U A has a small interfering alternating component.

The essential elements of the circuit are three energy stores and a switch (S), which is implemented in the usual structures in the form of a P-channel MOSFET and is periodically switched on and off by the control circuit ( not shown). The three energy stores are two coils ( L 1 and L 2 ) and a capacitor C 1 . These two coils can be designed as a double coil with two oppositely wound turns on a common core in order to improve the efficiency . The coil L 1 can also be designed as a transformer and thus a galvanic separation between input and output side can be achieved.

The parameter D is used to regulate the output voltage U A , which specifies the duty cycle (also referred to as "relative switch-on time" or "duty cycle") and can be between 0% and almost 100% - with a duty cycle of 100% the coil would L 1 in saturation fall and the input voltage U e short. The output voltage for the Zeta converter results from the input voltage U E as follows:

Individual evidence

  1. ↑ Cruz Martins, D. de Souza Campos, F. Barbi, I .: Zeta converter with high power factor operating in continuous conduction mode . Proceedings of the 1996 IEEE IECON - 22nd International Conference, Taipei 1996, p. 1802 to 1807 , doi : 10.1109 / IECON.1996.570741 ( ivobarbi.com [PDF]).
  2. ↑ Zeta Converter Basics (PDF; 100 kB), application note ANP29, Sipex, 2007 (English)