T
treez
Guest
Hi,
We wish to use Common mode chokes to reduce circulating currents in a large parallel array of SMPS modules. Power is 12kW….Vin = 650V and Vout = 48VDC.
(Actually vin = 800vdc but the input cable resistance is some 7 ohms so vin at the input to the SMPS will be some 650V)
We wish to put these common mode chokes at the input to each of the 14 DCDC modules.
Please help in locating ferrite torroids with sufficiently high permeability at >30MHz?
So, We have 14 DCDC modules in parallel. They are isolated, but we don’t need isolation, so we are connecting their primary and secondary grounds together, since isolated SMPS’s are generally more noisy (Common mode noise) than non-isolated SMPS’s.
However, the lack of isolation in each module means that the paralleled array presents many ground current loops (going under each module) in which noise currents can be induced.
As such, in order to arrest these noise currents we are going to add a common mode choke to the input of each DCDC module.
We are conscious that off-the-shelf offerings of common mode chokes for 800V, 2A input are too large for us. Also, the few small ones available have multiple windings close together and so interwinding capacitance will be an issue. Also, the availability of offtheshelf offerings is so poor that we are going to wind our own as attached.
The main point of this common mode choke is that it should limit these circulating noise currents which may actually get into the control inside the DCDC modules and stop them from working….ie rather than the main concern being passing EMC…the main concern here is to stop the power supply from malfunctioning due to the noise.
Do you know of any torroids with higher permeability at up to 60MHz than the 742701703 torroid from wurth? It appears to be a real difficulty finding ferrite torroids that have any kind of decent permeability above 1MHz.
742701703 torroid.
https://www.we-online.com/catalog/datasheet/742701703.pdf
We wish to use Common mode chokes to reduce circulating currents in a large parallel array of SMPS modules. Power is 12kW….Vin = 650V and Vout = 48VDC.
(Actually vin = 800vdc but the input cable resistance is some 7 ohms so vin at the input to the SMPS will be some 650V)
We wish to put these common mode chokes at the input to each of the 14 DCDC modules.
Please help in locating ferrite torroids with sufficiently high permeability at >30MHz?
So, We have 14 DCDC modules in parallel. They are isolated, but we don’t need isolation, so we are connecting their primary and secondary grounds together, since isolated SMPS’s are generally more noisy (Common mode noise) than non-isolated SMPS’s.
However, the lack of isolation in each module means that the paralleled array presents many ground current loops (going under each module) in which noise currents can be induced.
As such, in order to arrest these noise currents we are going to add a common mode choke to the input of each DCDC module.
We are conscious that off-the-shelf offerings of common mode chokes for 800V, 2A input are too large for us. Also, the few small ones available have multiple windings close together and so interwinding capacitance will be an issue. Also, the availability of offtheshelf offerings is so poor that we are going to wind our own as attached.
The main point of this common mode choke is that it should limit these circulating noise currents which may actually get into the control inside the DCDC modules and stop them from working….ie rather than the main concern being passing EMC…the main concern here is to stop the power supply from malfunctioning due to the noise.
Do you know of any torroids with higher permeability at up to 60MHz than the 742701703 torroid from wurth? It appears to be a real difficulty finding ferrite torroids that have any kind of decent permeability above 1MHz.
742701703 torroid.
https://www.we-online.com/catalog/datasheet/742701703.pdf
