Designing Smoothing Chokes

The smoothing choke is connected between the rectifier and the DC load. Normally its linear inductance is prescribed up to the nominal peak value of the load current. In some applications there are prescribed 2 values of the inductances:

– In the linear range of the induction in the core and
– In the on-linear range of the induction in the core.

If you need to have very wide range of continuous DCcurrent then you will need very high inductance at very low DC current. For this reason you will need to over bridge the gaps with some laminations:5%-10% of stack.

Normally the ripple of the DC current is not very big and the core losses and the eddy current losses in the winding are relative loq. For this reason there is no need to use big number of gaps per leg. and the expensive steel at the 50&60Hz applications.
If you need to use Cu or Al foil then you will need to use more gaps per leg.
The type of the inductance is always differentially: L-Type=4 at L&Freq
The frequency of the 1. Current harmonic depends on the net frequency and the rectifier type.

Smoothing Choke for 3 Phase Rectifier Bridge:

Input:

  • Set two LI-points:: 2 inductances at 2 peak currents. Note that the induction corresponds to the first current.
  • Select the differential inductance : L-Type = 4
  •  Select Cu flat wire: Wire = 3
  •  The frequency of the first harmonic is 300Hz
  • Set the harmonics of the thermal current: the rms-values of the first, 300Hz harmonic and 0 “harmonic” for the DC-current
  • Set the temperature rise
  • Select cheap steel. Note that the induction will be optimized by program in order to get 2 prescribed inductances at 2 prescribed currents.
  • Set Gap = 1 and Core Assembly = 2
  • Select suitable core family.

Output:

• Press Ctrl+L in order see the diagram Inductance vs. Current

Test:

• Round the number of turns
• Change the peak value of the second LI-point in order to increase the current range of the diagram Inductance vs. Current

Note:

• In order to calibrate the choke, connect it on the calculated calibration AC-voltage (rms value) with the calibration frequency (normally 50Hz or 60Hz) and then vary the gap until you get the calculated calibration AC-current (rms value).

Smoothing Choke for 1 Phase Rectifier Bridge:

Input:

• Set the LI-poin:f the inductanceand the induction at the peak current.
• Select the differential inductance : L-Type = 4
• Select Cu flat wire: Wire = 4
• The frequency of the first harmonic is 100Hz
• Set the harmonics of the thermal current: the rms-values of the first harmonic and of the DC-current , 0 “harmonic”
• Set the temperature rise
• Select cheap steel.
• Set Gap = 1 and Core Assembly = 2
• Select suitable core family.

Output:

• Press Ctrl+L in order see the diagram Inductance vs. Current

Test:

• Round the number of turns
• Change the peak value in order to increase the current range of the diagram Inductance vs. Current

Note:

• In order to calibrate the choke, connect it on the calculated calibration AC-voltage (rms value) with the calibration frequency (normally 50Hz or 60Hz) and then vary the gap until you get the calculated calibration AC-current (rms value).

High Frequency Smoothing Choke for 1 Phase Rectifier Bridge:

 

Input:

• Set the LI-point: the inductanceand tthe induction at the peak current.
• Select the differential inductan ce : L-Type = 4
• Select Cu flat wire: Wire = 0
• Select core material: feriittee with high permeabilty or powder
• The frequency of the first harmonic is 50000Hz
• Set the harmonics of the thermal current: the rms-values of the first harmonic and of the DC-current
• Set the temperature rise
• Select suitable core family and the gap position.

Output:

• Press Ctrl+L in order see the diagram Inductance vs. Current

Test:

• Round the number of turns
• Change the peak value in order to increase the current range of the diagram Inductance vs. Current

Note:

• In order to calibrate the choke, connect it on the calculated calibration AC-voltage (rms value) with the calibration frequency (normally 50Hz or 60Hz) and then vary the gap until you get the calculated calibration AC-current (rms value).