Sine-Wave Chokes.pdf

The international standard IEC EN 61000-3-2 defines limits for harmonic current emissions in electrical equipment with input current ≤16 A per phase.
Switch-mode power supplies can be modified to have a current flow near to a sinusoidal using a "pump circuit" built around a "sine-wave choke".
The sine-wave choke reduces harmonics and interference voltages in the MHz range, and is a more efficient and reliable solution than traditional cut-off circuits.
EPCOS has developed a range of sine-wave chokes with low losses and high saturation limits, suitable for switch-mode power supplies up to 300 W.
The sine-wave chokes are designed to be environmentally friendly and can be completely recycled.
The use of sine-wave chokes leads to lower interference voltages, reduced harmonics, and increased efficiency in switch-mode power supplies.

Technical Details:

The sine-wave choke is used in a "pump circuit" to modify the switch-mode power supply and reduce harmonics.
The choke has a low saturation limit and high permeability ferrite material, with an air gap to prevent saturation at high currents.
The hysteresis curve of the choke is sheared apart due to the air gap, allowing the core to become saturated at a higher current.
The sine-wave choke reduces interference voltages in the MHz range and is a more reliable and efficient solution than traditional active circuits.

Applications:

Switch-mode power supplies for personal computers, monitors, and TV receivers (Class D devices).
Switch-mode power supplies up to 300 W, with potential for higher-powered applications.
* Applications where reduced harmonics and interference voltages are required.