Using Wolpert


Equations without losses

$$\frac{E_s}{E_p} = \frac{N_s}{N_p}$$$$\frac{I_s}{I_p} = \frac{N_P}{N_S}$$

$E_s$ = Secondary voltage
$E_p$ = Primary voltage
$I_s$ = Secondary current
$I_p$ = Primary voltage
$N_s$ = Secondary turns
$N_p$ = Primary turns

$$VA = E_p * I_p = E_s * I_s$$


Equations with losses

$$VA = E_s * I_s$$$$I_p = \frac{VA * efficiency}{E_p}$$$$Area_{effective} = Area_{core} * stackingFactor$$

$Area_{effective}$ = core area (tongue width * stack height)
stackingFactor = use 0.92 for 1x1 interleave and 0.95 for butt stack

$$N_p = \frac{E_p * 10^8}{4.44 * B * A * F}$$

4.44 is a constant for sine wave operation
B = flux density in $\frac{lines}{inch^2}$
A = $Area_{effective}$
F = line frequency

$$N_s = \frac{N_p}{E_p} * lossFactor * E_s$$

lossFactor = factor to adjust turns to compensate for losses

$$T_{rise} = \frac{totalLoss}{0.1*{(\frac{weight}{1.073})}^\frac{2}{3}}$$$$\%_{regulation} = \frac{E_{noLoad} - E_{fullLoad}}{E_{fullLoad}} * 100\%$$

Calculation Steps

  • Sum desired secondary VAs, voltage * current
  • Calculate primary current including efficiency
  • Calculate effective core area using stacking factor
  • Calculate primary turns
  • Calculate secondary turns
  • Calculate primary and secondary wire diameters
  • Calculate primary and secondary layer count
  • Loop
    • Calculate all windings mean path length
    • Calculate all windings resistance
    • Calculate all winding voltage drops
    • Find secondary turn count that minimizes abs($V_{desired} - V_{out}$)
  • Calculate winding weight
  • Calculate transformer weight including extras: lead wire, bells, brackets
  • Calculate temperature rise above ambient, ($T_{ambient} + T_{rise}$) < 105C, Wolpert p25

Additional Considerations

  • Choice of flux density affects primary turn count, which results in an integer
    • Voltage ratios are a fractional number of 2 integer divisions
    • By changing the flux density, you can minutely alter the secondary output voltages
    • The fluxFind() method scans flux densities and returns density with minimal output error
    • While fluxFind() finds optimal density, you may opt for lower density to avoid saturation when using recycled, or unknown, laminations
  • Lowering circularMilsPerAmp results in smaller gauge wire with higher operating temperature. The default value of 800 is fairly conservative. If you're design doesn't quite fit, lower circularMilsPerAmp and see what happens to bobbin fill percentage and temperature rise
  • 29M6 GOSS laminations have coreLoss of 0.66 watts/lb, see Wolpert P24. Foster rep loosely stated their non-oriented lamination loss is 5W/lb at 13kGauss. You can see this in data sheets from AK Steel of ATI. In summary, non-oriented steel will have higher core losses hence higher temperature rise. However, they also have lower inrush current. If you're recycling laminations, chances are they are not oriented. You also don't know saturation, so choose a low flux density, which will increase turns and fill your bobbin.

In [2]:
%matplotlib notebook
import Winding,Transformer
import matplotlib.pyplot as plt
import numpy as np
import math

Here are the default transformer parameter values

laminationVA           = lamva      
circularMilsPerAmp     = 800.0
coreLoss               = 0.66  # watts/lbs
efficiency             = 0.90  # 1/1.11 in wolpert p10
                               # estimate w/o calculating primary leakage inductance
lineFrequency          = 60.0       
stackingFactor         = 0.92  # stacking factor wolpert p11 
                               #  0.92 1x1 interleave, 0.95 butt stack
lossFactor             = 0.95  # 1/1.05 in wolpert p11
isolationThickness     = 0.003 # 1 mil kapton
wrappingThickness      = 0.015      
weightExtra            = 1.15  # percentage of extra: bells, brackets, screws
insulationLayers       = 3

In [10]:
# Simple 12V 3A filament transformer

%reload_ext autoreload

primary      = Winding.Winding('p',115.0,0.0)
secondary    = Winding.Winding('s', 12.6,3.0,taps=[50])

t = Transformer.Transformer([primary,secondary],50,have=1)

t.circularMilsPerAmp = 600

#t.fluxDensity = 87000

t.fluxDensity = t.fluxFind(bmax=90000)

t.compute()
t.report()
t.fluxTable()


Requirements
  Primary              = 115.0 V
  Secondary            =  12.6 V @ 3.000 A Taps 50
  Size                 = EI-1
  AWG Selection        = 40 37 34 32 31 27 24 22 20 18 15 
  VA Selection         = 50.0 VA

Transformer
  VA Computed          = 37.8 VA
  Flux Density         = 87000 lines, 13485 gauss
  Circular Mils/Amp    = 600
  Weight               = 2.6lbs
  Loss                 = 2.6W
  Temp Rise            = 14C

Lamination
  Size                 = EI-1
  Stack Height         = 1.25
  Stacking Factor      = 0.920
  Core Area            = 1.250 in*in
  Core Area Effective  = 1.150 in*in
  Window Height        = 0.5
  Window Length        = 1.5

Windings
  Type                  Primary     Secondary   
  Voltage V             115.0       12.6        
  Current A             0.4         3.0         
  Turns                 431         49          
  Layers                7           3           
  Turns/layer           62          22          
  AWG                   24          15          
  Wire Diameter         0.0215      0.059       
  Ohms/1000 feet        25.6800     3.1836      
  Mean Path Length inch 5.42        6.76        
  Wire Length feet      194.7       27.6        
  Resistance            5.0009      0.0878      
  Voltage Drop          1.826       0.263       
  Voltage Out                       12.60       
  Voltage No Load                   13.07       
  Voltage Regulation                3.74        
  Fill Last Layer       True        True        

Bobbin
  Winding Length       = 1.340 in
  Winding Stack
    Description          Layers Turns T/L   Height LHeight
    Bobbin Base          1      1     1     0.040  0.040  
    Primary 24AWG        7      431   62    0.150  0.021  
    Insulation           3      1     1     0.009  0.003  
    Secondary 15AWG      3      49    22    0.177  0.059  
    Wrapping             3      1     1     0.045  0.015  
  Stack Height         = 0.42 in
  Window Height        = 0.50 in
  Fill                 = 84.3 % 


Core Size EI-1
FluxDen  Gauss  Fill  Loss     12.60  No Load   Error
-----------------------------------------------------------------------------------------
50000    7751   121   4.2      12.67  13.65     8.26
51000    7906   117   4.0      12.65  13.59     7.85
52000    8062   117   4.0      12.64  13.56     7.58
53000    8217   117   3.9      12.58  13.48     7.27
54000    8372   117   3.9      12.53  13.40     7.59
55000    8527   113   3.8      12.64  13.49     7.04
56000    8682   113   3.7      12.56  13.39     6.91
57000    8837   113   3.7      12.64  13.46     6.78
58000    8992   113   3.6      12.53  13.33     6.88
59000    9147   113   3.6      12.59  13.38     6.28
60000    9302   113   3.5      12.66  13.43     6.57
61000    9457   108   3.4      12.54  13.28     6.40
62000    9612   108   3.4      12.58  13.31     5.98
63000    9767   108   3.4      12.62  13.34     5.83
64000    9922   97    3.3      12.65  13.34     5.89
65000    10077  97    3.3      12.67  13.35     5.95
66000    10232  97    3.2      12.69  13.36     6.01
67000    10387  92    3.2      12.70  13.35     5.89
68000    10542  92    3.1      12.69  13.33     5.78
69000    10697  92    3.1      12.69  13.32     5.66
70000    10852  92    3.1      12.68  13.30     5.54
71000    11007  92    3.1      12.67  13.29     5.41
72000    11162  92    3.0      12.64  13.24     5.09
73000    11317  92    3.0      12.61  13.20     4.76
74000    11472  92    3.0      12.57  13.16     4.83
75000    11627  92    2.9      12.54  13.11     5.05
76000    11782  88    2.9      12.51  13.06     5.09
77000    11937  88    2.9      12.67  13.22     4.92
78000    12093  88    2.8      12.61  13.15     4.36
79000    12248  88    2.8      12.54  13.07     4.68
80000    12403  88    2.8      12.71  13.24     5.04
81000    12558  88    2.8      12.64  13.16     4.46
82000    12713  88    2.8      12.57  13.09     4.26
83000    12868  88    2.7      12.72  13.23     4.95
84000    13023  88    2.7      12.65  13.15     4.35
85000    13178  88    2.7      12.55  13.04     4.33
86000    13333  84    2.7      12.71  13.19     4.63
87000    13488  84    2.6      12.60  13.07     3.76
88000    13643  84    2.6      12.50  12.96     4.52
89000    13798  84    2.6      12.65  13.11     4.04
90000    13953  84    2.6      12.51  12.96     4.33
91000    14108  84    2.6      12.67  13.12     4.10
92000    14263  84    2.6      12.52  12.97     4.14
93000    14418  84    2.5      12.68  13.13     4.15
94000    14573  72    2.5      12.55  12.97     3.81
95000    14728  72    2.5      12.68  13.10     3.95
96000    14883  72    2.5      12.53  12.94     3.90
97000    15038  72    2.5      12.69  13.11     4.01
98000    15193  72    2.4      12.51  12.91     3.99
99000    15348  72    2.4      12.64  13.05     3.54
100000   15503  72    2.4      12.48  12.88     4.10
101000   15658  68    2.4      12.63  13.02     3.32
102000   15813  68    2.4      12.74  13.12     4.12

In [14]:
print t.gcode()


(-----------------------------------------------------------)
(-- Requirements -------------------------------------------)
(  Primary              = 115.0 V                           )
(  Secondary            =  12.6 V @ 3.000 A Taps 50         )
(  Size                 = EI-1                              )
(  AWG Selection        = 40 37 34 32 31 27 24 22 20 18 15  )
(  VA Selection         =  50.0 VA                          )

(-- setup -------------------------------------)
( inches, work offset 54, absolute, linear 125%)
G20 G54 G90
G1 F125

(-- winding -  115.0V Primary    --------------)
( load #24 AWG wire                            )
( winding  368 turns, fill last True           )
( move to 0.0                                  )
( wind leadin                                  )
M0
X1.3330     Y62.0000        ( right            )
X0.0000     Y124.0000       ( left             )
X1.3330     Y186.0000       ( right            )
X0.0000     Y248.0000       ( left             )
X1.3330     Y310.0000       ( right            )
X0.0000     Y368.0000       ( left             )

(-- winding -   12.6V Secondary  --------------)
( load #15 AWG wire                            )
( winding   42 turns, fill last True           )
( move to 0.0                                  )
( wind leadin                                  )
M0
X0.6490     Y11.0000        ( right tape       )
M0                          ( right tape       )
X1.2390     Y21.0000        ( right tap        )
M0                          ( right tap        )
X1.2980     Y22.0000        ( right            )
X0.0000     Y42.0000        ( left             )



In [ ]:
# Simple 12V filament transformer
# now use fluxfind

%reload_ext autoreload

primary      = Winding.Winding('p',115.0,0.0)
secondary    = Winding.Winding('s', 12.6,3.0,taps=[50])

t = Transformer.Transformer([primary,secondary],50,have=0)

t.fluxDensity = t.fluxFind(bmax=100000,inc=100) # this scans through flux densities and finds minimal error for output voltage
t.compute()
t.report()

In [ ]:
# Simple 12V filament transformer
# now use fluxfind and force bigger wire gauge to improve regulation

%reload_ext autoreload

primary      = Winding.Winding('p',115.0,0.0)
secondary    = Winding.Winding('s', 12.6,3.0,taps=[50])

t = Transformer.Transformer([primary,secondary],50,have=0)
t.circularMilsPerAmp = 1000

t.fluxDensity = t.fluxFind(bmax=100000,inc=500) # this scans through flux densities and finds minimal error for output voltage
t.compute()
t.report()

In [ ]:
# Simple 12V filament transformer
# now use fluxfind and choose from wire I have

%reload_ext autoreload

primary      = Winding.Winding('p',115.0,0.0,fill=0)
secondary    = Winding.Winding('s', 12.6,3.0,taps=[50])

t = Transformer.Transformer([primary,secondary],50,have=1)

t.fluxDensity = t.fluxFind(bmax=100000,inc=500) # this scans through flux densities and finds minimal error for output voltage
t.compute()
t.report()

In [ ]:
t.plot(1)

In [ ]:
print t.gcode()

In [25]:
# 6V6GT Push-Pull AB2 Power Transformer, Fender Deluxe 5E3
# 1 12AX7, 1 12AY7, 2 6V6GT, 1 5Y3

%reload_ext autoreload

primary      = Winding.Winding('p',115.0,0.0)
secondary5   = Winding.Winding('s',  5.0,2.0,fill=0)              #filament rectifier
secondary6   = Winding.Winding('s',  6.3,1.7,taps=[50])    #filaments 6v6,12ax7, 12ay7
secondary325 = Winding.Winding('s',325.0,0.125,taps=[50])  #plate
secondary20  = Winding.Winding('s', 20.0,0.002,None)       #fixed bias

t = Transformer.Transformer([secondary5,secondary6,primary,secondary325,secondary20],65) # windings order by gauge
t.coreLoss           = 0.66  # watts/lb GOES lam
t.wrappingThickness  = 0.005
t.insulationLayers   = 2
t.circularMilsPerAmp = 650

#t.fluxDensity = 75000
t.fluxDensity = t.fluxFind(bmax=100000,inc=500) # this scans through flux densities and finds minimal error for output voltage
t.compute()
t.report()
t.fluxTable()


Requirements
  Primary              = 115.0 V
  Secondary            =   5.0 V @ 2.000 A 
  Secondary            =   6.3 V @ 1.700 A Taps 50
  Secondary            = 325.0 V @ 0.125 A Taps 50
  Secondary            =  20.0 V @ 0.002 A 
  Size                 = EI-1 1/8
  AWG Selection        = 40 37 34 32 31 27 24 22 20 18 15 
  VA Selection         = 65.0 VA

Transformer
  VA Computed          = 61.4 VA
  Flux Density         = 99000 lines, 15345 gauss
  Circular Mils/Amp    = 650
  Weight               = 3.2lbs
  Loss                 = 4.0W
  Temp Rise            = 19C

Lamination
  Size                 = EI-1 1/8
  Stack Height         = 1.125
  Stacking Factor      = 0.920
  Core Area            = 1.265 in*in
  Core Area Effective  = 1.164 in*in
  Window Height        = 0.5625
  Window Length        = 1.6875

Windings
  Type                  Secondary   Secondary   Primary     Secondary   Secondary   
  Voltage V             5.0         6.3         115.0       325.0       20.0        
  Current A             2.0         1.7         0.6         0.1         0.0         
  Turns                 17          21          374         1098        67          
  Layers                1           1           6           12          1           
  Turns/layer           36          36          71          99          424         
  AWG                   18          18          24          27          40          
  Wire Diameter         0.0421      0.0421      0.0215      0.0154      0.0036      
  Ohms/1000 feet        6.3840      6.3840      25.6800     51.4800     1049.0400   
  Mean Path Length inch 4.99        5.35        6.06        7.34        8.11        
  Wire Length feet      7.1         9.4         188.8       671.2       45.3        
  Resistance            0.0451      0.0597      4.8474      34.5542     47.5207     
  Voltage Drop          0.090       0.102       2.874       4.319       0.095       
  Voltage Out           5.01        6.19                    324.86      19.99       
  Voltage No Load       5.23        6.46                    337.62      20.60       
  Voltage Regulation    4.41        4.25                    3.93        3.05        
  Fill Last Layer       0           True        True        True        True        

Bobbin
  Winding Length       = 1.527 in
  Winding Stack
    Description          Layers Turns T/L   Height LHeight
    Bobbin Base          1      1     1     0.040  0.040  
    Secondary 18AWG      1      17    36    0.042  0.042  47% layer filled
    Insulation           2      1     1     0.006  0.003  
    Secondary 18AWG      1      21    36    0.042  0.042  58% layer filled
    Insulation           2      1     1     0.006  0.003  
    Primary 24AWG        6      374   71    0.129  0.021  
    Insulation           2      1     1     0.006  0.003  
    Secondary 27AWG      12     1098  99    0.185  0.015  
    Insulation           2      1     1     0.006  0.003  
    Secondary 40AWG      1      67    424   0.004  0.004  15% layer filled
    Wrapping             2      1     1     0.010  0.005  
  Stack Height         = 0.48 in
  Window Height        = 0.56 in
  Fill                 = 84.6 % 


Core Size EI-1 1/8
FluxDen  Gauss  Fill  Loss     5.00   No Load 6.30   No Load 325.00 No Load 20.00  No Load   Error
-----------------------------------------------------------------------------------------
50000    7751   144   7.3      4.94   5.43   6.37   6.98   325.03 356.33 19.96  21.42     9.72
51000    7906   141   7.2      5.05   5.54   6.36   6.96   325.03 355.60 19.93  21.35     9.47
52000    8062   141   7.1      5.01   5.48   6.35   6.94   325.07 355.00 20.05  21.45     9.03
53000    8217   134   6.9      4.97   5.43   6.34   6.91   324.99 353.72 20.04  21.39     8.79
54000    8372   134   6.8      5.07   5.53   6.32   6.87   325.06 353.21 19.97  21.29     8.74
55000    8527   131   6.7      5.02   5.46   6.28   6.82   324.97 352.51 20.04  21.33     8.29
56000    8682   131   6.6      4.96   5.39   6.25   6.77   324.94 351.95 19.93  21.19     8.47
57000    8837   131   6.5      5.06   5.48   6.37   6.90   325.06 351.55 19.99  21.23     8.36
58000    8992   125   6.3      4.99   5.40   6.33   6.84   325.07 350.58 20.04  21.24     7.77
59000    9147   125   6.2      5.08   5.49   6.28   6.78   324.92 349.94 20.06  21.24     7.97
60000    9302   115   5.9      5.01   5.40   6.24   6.70   325.03 348.35 19.93  21.03     7.34
61000    9457   115   5.9      4.92   5.30   6.35   6.81   324.93 347.84 19.92  21.00     7.50
62000    9612   115   5.8      5.01   5.38   6.28   6.73   324.99 347.50 20.09  21.15     6.95
63000    9767   112   5.7      4.92   5.28   6.21   6.65   324.92 346.96 20.08  21.12     7.44
64000    9922   112   5.6      5.00   5.36   6.32   6.75   324.91 346.59 20.03  21.05     6.59
65000    10077  112   5.6      5.09   5.45   6.23   6.66   325.08 346.41 19.98  20.98     7.09
66000    10232  108   5.5      4.98   5.32   6.33   6.75   324.97 345.61 20.10  21.08     6.56
67000    10387  105   5.4      5.06   5.41   6.25   6.65   324.98 345.21 20.05  21.00     6.66
68000    10542  105   5.3      4.94   5.28   6.34   6.75   325.07 345.00 19.95  20.89     6.51
69000    10697  105   5.3      5.02   5.35   6.24   6.64   324.96 344.57 20.06  20.99     6.31
70000    10852  103   5.2      4.90   5.22   6.34   6.74   325.10 344.35 19.96  20.87     6.53
71000    11007  103   5.1      4.97   5.29   6.23   6.61   324.93 343.90 20.03  20.93     6.20
72000    11162  103   5.1      5.04   5.36   6.32   6.70   324.95 343.66 20.10  20.99     6.03
73000    11317  103   5.0      4.90   5.21   6.20   6.56   324.98 343.42 19.96  20.83     6.52
74000    11472  103   5.0      4.98   5.28   6.29   6.66   324.99 343.16 20.03  20.89     5.68
75000    11627  96    4.9      5.05   5.35   6.38   6.75   324.90 342.44 19.89  20.72     6.05
76000    11782  96    4.8      4.90   5.18   6.24   6.60   325.09 342.41 19.92  20.74     6.11
77000    11937  96    4.8      4.97   5.26   6.34   6.69   325.07 342.13 19.99  20.80     5.49
78000    12093  96    4.7      5.04   5.33   6.20   6.54   325.02 341.85 20.02  20.82     5.74
79000    12248  96    4.7      5.11   5.39   6.28   6.62   324.96 341.57 20.05  20.84     5.70
80000    12403  93    4.6      4.94   5.22   6.37   6.71   324.94 341.27 20.08  20.86     5.62
81000    12558  93    4.6      5.01   5.28   6.21   6.54   325.11 341.23 20.12  20.89     5.44
82000    12713  93    4.6      5.07   5.34   6.29   6.62   325.00 340.93 20.10  20.86     5.35
83000    12868  93    4.5      4.89   5.16   6.38   6.70   324.91 340.62 19.88  20.63     5.75
84000    13023  93    4.5      4.95   5.22   6.20   6.52   325.04 340.57 20.12  20.86     5.49
85000    13178  93    4.5      5.01   5.28   6.28   6.59   324.92 340.25 20.10  20.84     4.94
86000    13333  91    4.4      5.07   5.34   6.35   6.67   325.08 340.20 20.09  20.81     5.29
87000    13488  87    4.3      4.88   5.13   6.18   6.48   324.94 339.60 20.08  20.79     5.69
88000    13643  87    4.3      4.94   5.19   6.26   6.56   325.05 339.54 20.07  20.76     4.98
89000    13798  87    4.3      5.01   5.25   6.33   6.63   324.90 339.19 20.05  20.73     4.60
90000    13953  87    4.2      5.06   5.30   6.40   6.70   324.98 339.14 19.98  20.66     5.02
91000    14108  87    4.2      5.12   5.37   6.21   6.50   325.08 339.07 19.96  20.63     5.28
92000    14263  84    4.2      4.90   5.14   6.28   6.56   324.93 338.72 19.89  20.55     4.96
93000    14418  84    4.1      4.97   5.20   6.36   6.65   325.03 338.64 19.87  20.52     4.73
94000    14573  84    4.1      5.02   5.25   6.43   6.71   325.10 338.58 20.08  20.72     4.82
95000    14728  84    4.1      5.07   5.31   6.21   6.49   324.89 338.22 20.00  20.64     4.82
96000    14883  84    4.0      5.13   5.36   6.28   6.55   324.96 338.15 19.93  20.56     4.84
97000    15038  84    4.0      4.90   5.12   6.35   6.62   325.03 338.08 20.14  20.77     4.89
98000    15193  84    4.0      4.95   5.17   6.42   6.69   325.09 338.00 20.07  20.69     4.75
99000    15348  84    4.0      5.01   5.23   6.19   6.46   324.86 337.62 19.99  20.60     4.39
100000   15503  81    3.9      5.06   5.28   6.26   6.53   324.96 337.54 19.91  20.51     4.43
101000   15658  81    3.9      5.11   5.33   6.32   6.58   325.00 337.48 20.08  20.68     4.52
102000   15813  81    3.9      4.86   5.07   6.39   6.65   325.06 337.40 20.00  20.59     4.86

In [26]:
t.plot(0)



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print t.gcode()

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t.fluxTable()
t.fluxTable(sort='error')

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%reload_ext autoreload

# here's a filament transformer design using EI150 lamination
# I'm using this for a bench power supply
# 5.0V@5A, 6.3V@8A, 12.6V@6A

primary      = Winding.Winding('p',115.0,0.0,None)
secondary5a  = Winding.Winding('s',5.0 ,2.5,[50])
secondary5b  = Winding.Winding('s',5.0 ,2.5,[50])
secondary6a  = Winding.Winding('s',6.3 ,4.0,[50])
secondary6b  = Winding.Winding('s',6.3 ,4.0,[50])
secondary12a = Winding.Winding('s',12.6,3.0,[50])
secondary12b = Winding.Winding('s',12.6,3.0,[50])

t = Transformer.Transformer([primary,secondary6a,secondary6b,secondary12a,secondary12b,secondary5a,secondary5b],160,have=1)
t.coreLoss           = 0.8  # watts/lb, using AK DI-MAX M-13 at 12kG
t.isolationThickness = 0.003
t.wrappingThickness  = 0.005
t.insulationLayers   = 2

t.fluxDensity = t.fluxFind(bmax=100000,inc=500) # this scans through flux densities and finds minimal error for output voltage
t.compute()
t.report()

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print t.gcode()

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# grid bias transformer

primary   = Winding.Winding('p',115.0,0.0,None)
secondary = Winding.Winding('s',100.0 ,0.020,[50])

t = Transformer.Transformer([primary,secondary],7)
t.coreLoss           = 0.66 # watts/lbs, goes

t.fluxDensity = t.fluxFind(bmax=100000)
#t.fluxDensity = 90000
t.compute()
t.report()
t.fluxTable()
t.fluxTable(sort='error')

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# power transformer for a flyback tube output stage screen bias 200V

primary       = Winding.Winding('p',115.0,0.0,None)
secondary5    = Winding.Winding('s',5.0,2.0,None)
secondary6    = Winding.Winding('s',6.3,2.0,[50])
secondary200  = Winding.Winding('s',200.0,0.05,None)
secondary500  = Winding.Winding('s',500.0,0.100,[50])

t = Transformer.Transformer([secondary5,secondary6,primary,secondary500,secondary200],90)
t.circularMilsPerAmp = 700
t.coreLoss           = 0.88 # watts/lbs
t.wrappingThickness  = 0.05

t.fluxDensity = t.fluxFind()
t.compute()
t.report()

t.fluxTable()
t.fluxTable(sort='error')

To Do

$$L_S = \frac{10.6N^2MT(2nc + a)}{10^9n^2b}$$
  • $L_S$ = leakage inductance of both windings in henrys, referred to the winding having N turns
  • $MT$ = mean length of turn for the whole coil in inches
  • $n$ = number of dielectrics between winding ( $n$ = 2 in Fig 57, see link above )
  • $c$ = thickness of dielectric between winding in inches
  • $a$ = winding height in inches
  • $b$ = winding traverse in inches
  • Calculate primary voltage drop using leakage inductance instead of efficiency estimate

  • if tap lands at route direction change, tap doesn't show up on plot

  • secondary VA calculation incorrect if secondary driving a rectifier, winding needs rectifier option


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