Core losses in dual big inductors

[Joerg]

On Sat, 27 Jul 2013 15:36:45 -0700, Jim Thompson wrote:

Though some have said there's a "Chan" model in LTspice. Is Joerg
overlooking a built-in solution for those who adhere to "free" ?

Quick and dirty simulation to plot B-H loop of EP7 core in H5A ferrite.
Ungapped, alter parameter LG for required gap (in meters):

Use the plot file (at end) to set plot to read directly in amp/meter and tesla.

Version 4
SHEET 1 1008 680
WIRE 192 80 -32 80
WIRE 448 80 304 80
WIRE 512 80 448 80
WIRE 304 96 304 80
WIRE 448 96 448 80
WIRE -32 128 -32 80
WIRE 192 128 192 80
WIRE -32 256 -32 208
WIRE 80 256 -32 256
WIRE 192 256 192 208
WIRE 192 256 80 256
WIRE 80 288 80 256
FLAG 80 288 0
FLAG 512 80 OUT
IOPIN 512 80 Out
FLAG 304 176 0
FLAG 448 176 0
SYMBOL ind 176 112 R0
WINDOW 3 29 104 Left 2
SYMATTR Value Hc=8 Br=100e-3 Bs=410e-3 Lm=15.7e-3 Lg=0 A=10.3e-6 N=10
SYMATTR InstName L1
SYMBOL bv 304 80 R0
SYMATTR InstName B1
SYMATTR Value V=idt(v(n001))
SYMBOL current -32 208 R180
WINDOW 0 24 80 Left 2
WINDOW 3 -106 36 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName I1
SYMATTR Value SINE(0 .5 1000)
SYMBOL res 432 80 R0
SYMATTR InstName RB1
SYMATTR Value 1meg
TEXT -40 296 Left 2 !.tran 0 2m 0 100n


Plot File:

[Transient Analysis]
{
Npanes: 1
{
traces: 1 {524290,0,"V(out)/(10*10.3e-6)"}
Parametric: "I(L1)*10/15.7e-3"
X: (' ',0,-420,70,420)
Y[0]: ('m',0,-0.4,0.08,0.4)
Y[1]: ('_',0,1e+308,0,-1e+308)
Volts: ('m',0,0,0,-0.4,0.08,0.4)
Log: 0 0 0
GridStyle: 1
}
}

Thanks, Fred!

Am I correct in assuming, no loop, no losses?

Does saturation have a loss mechanism?

I find that I can lose semiconductors when magnetics saturate !

boB

No, no, you don't really lose them. They just transfer from a solid
state into a vapor state but they are still there, somehow ...

 

[Fred Abse]

I find that I can lose semiconductors when magnetics saturate !

 

[Fred Abse]

Thanks, Fred!

Am I correct in assuming, no loop, no losses?

Does saturation have a loss mechanism?

Use this .plt file, with the model I already posted, giving losses in the
inductor.

Make sure that you set rser=0 l-(

Play with the Chan model constants, you'll find that losses are due to
coercivity, rather than saturation. Ignore the Spice artifact spikes
(smaller maxstep helps).

Hysteresis loss isn't the whole enchilada, by any means.

Plot file:

[Transient Analysis]
{
Npanes: 2
Active Pane: 1
{
traces: 1 {524290,0,"V(out)/(10*10.3e-6)"}
Parametric: "I(L1)*10/15.7e-3"
X: (' ',0,0,30,330)
Y[0]: ('m',1,0,0.0001,0.0012)
Y[1]: ('_',0,1e+308,0,-1e+308)
Volts: ('m',0,0,1,0,0.0001,0.0012)
Log: 0 0 0
GridStyle: 1
},
{
traces: 1 {524291,0,"V(N001)*I(L1)"}
X: ('u',0,0,2e-005,0.00018)
Y[0]: ('m',0,0,0.007,0.07)
Y[1]: ('_',0,1e+308,0,-1e+308)
Units: "W" ('m',0,0,0,0,0.007,0.07)
Log: 0 0 0
GridStyle: 1
}
}

 

[Fred Abse]

I also found a paper by Hermann Haus and Jim Melcher (one of my grad
student mentors while I was at MIT) which thoroughly discusses the
problem. I'll see if I can't set the math to a behavioral model that will
work with all flavors of Spice.

I look forward to it.

I wish that LTspice would allow you to label axes, like I can do with
Berkeley, using gnuplot.

 

[Fred Abse]

PSpice allows text, arrows, circles, etc. to be added to plots.

So does LTspice.

 

[Fred Abse]

Thanks, Fred, I'll get it a twirl.

For some reason, the plot file I posted "windows" the plot.

You need the full data.

Either "zoom full extents", before integrating the power waveform, or use
this one instead:

Increasing Hc from 8 to 20 approximately doubles the hysteresis loss.

Here's a plot file that does what I intended:


[Transient Analysis]
{
Npanes: 2
Active Pane: 1
{
traces: 1 {524290,0,"V(out)/(10*10.3e-6)"}
Parametric: "I(L1)*10/15.7e-3"
X: (' ',0,-420,70,420)
Y[0]: ('m',0,-0.4,0.08,0.4)
Y[1]: ('_',0,1e+308,0,-1e+308)
Volts: ('m',0,0,0,-0.4,0.08,0.4)
Log: 0 0 0
GridStyle: 1
},
{
traces: 1 {524291,0,"V(N001)*I(L1)"}
X: ('m',1,0,0.0002,0.002)
Y[0]: ('m',0,-0.028,0.007,0.049)
Y[1]: ('_',0,1e+308,0,-1e+308)
Units: "W" ('m',0,0,0,-0.028,0.007,0.049)
Log: 0 0 0
GridStyle: 1
}
}