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变压器 SPICE 模型  

2008-06-16 22:30:13|  分类: 集成电路(IC设计 |  标签: |举报 |字号 订阅

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铁芯变压器的一个 SPICE 模型

 

Here is the 3f4 Spice transformer I have used with some accuracy:

*XXFMR:Core Transformer Subcircuit Parameters ×铁芯变压器子电路参数

*XXFMR:PRIT:|Primary number of turns [0,]|1 ×初级绕组圈数

*XXFMR:PRIR:|Primary resistance [0,]|0.1 ×初级阻抗

*XXFMR:PRIL:|Primary leakage inductance [0,]|1u ×初级漏感

*XXFMR:SECT:|Secondary number of turns [0,]|1 ×次级绕组圈数

*XXFMR:SECR:|Secondary resistance [0,]|0.1 ×次级阻抗

*XXFMR:SECL:|Secondary leakage inductance [0,]|1u 次级漏感

*XXFMR:AREA:|Cross-sectional area [0,]|1" ×交叉部分面积

*XXFMR:LEN:|Core length [0,]|1" ×铁芯长度

*XXFMR:DOMAIN:|Input smoothing domain [1e-12, 0.5]|0.01" ×输入平滑范围

*XXFMR:FRAC:|Smoothing fraction/abs switch [T/F]|TRUE"

*XXFMR:MODE:|Mode switch (1= pwl, 2=hyst) [1,2]|1" ×模式开关

*XXFMR:LOW:|Input low value|0" ×输入低值

*XXFMR:HIGH:|Input high value|1" ×输入高值

*XXFMR:HYST:|Hysteresis [-1,]|0.1" ×磁滞

*XXFMR:LOWER:|Output lower limit|0" ×输出下限

*XXFMR:UPPER:|Output upper limit|1" ×输出上限

*XXFMR:H1:|Magnetic field array value|0" ×磁场矩阵值

*XXFMR:B1:|Flux density array value|0" ×磁通密度矩阵值

*XXFMR:H2:|Magnetic field array value|0" ×磁场矩阵值

*XXFMR:B2:|Flux density array value|0" ×磁通密度矩阵值

*XXFMR:H3:|Magnetic field array value|0" 磁场矩阵值

*XXFMR:B3:|Flux density array value|0"

*XXFMR:H4:|Magnetic field array value|0"

*XXFMR:B4:|Flux density array value|0"

*XXFMR:H5:|Magnetic field array value|0"

*XXFMR:B5:|Flux density array value|0"

{PRIT=1 PRIR=0.1 PRIL=1u SECT=1 SECR=0.1 SECL=1u AREA=1 LEN=1

DOMAIN=0.01 FRAC=TRUE MODE=1 LOW=0 HIGH=1 HYST=0.1 LOWER=0 UPPER=1

H1=0 B1=0 H2=1 B2=1 H3=1 B3=1 H4=1 B4=1 H5=1 B5=1}

*Generic type:xfmr

.SUBCKT XXFMR 1 2 3 4

RPRI 1 5 {PRIR}

LPRI 5 6 {PRIL}

RSEC 3 7 {SECR}

LSEC 7 8 {SECL}

APRI 6 2 9 0 PRILC

ASEC 8 4 10 0 SECLC

ACORE 9 10 CORE

.MODEL PRILC lcouple(num_turns={PRIT})

.MODEL SECLC lcouple(num_turns={SECT})

.MODEL CORE core(area={AREA} length={LEN} input_domain={DOMAIN}

+ fraction={FRAC} mode={MODE} in_low={LOW} in_high={HIGH}

+ hyst={HYST} out_lower_limit={LOWER} out_upper_limit={UPPER}

+ H_array=[{H1} {H2} {H3} {H4} {H5}]

+ B_array=[{B1} {B2} {B3} {B4} {B5}] )

.ENDS XXFMR

*Default alias:XXFMR {PRIT=5000 PRIR=1500 PRIL=0.25 SECT=2000 SECR=300

SECL=0.0005 LEN=1.25 FRAC=TRUE}

.PARAM ADEFAULT

Change only the figures in "*Default alias:". Set up your PRIT with

your calculated primary turns deduced from the tranny's AL parameter.

The SECT can be figured out from the impedance ratio you want. The

PRIR and SECR are the resistance values that you can determine from

the gague of wire that you will use and roughly how long the winding

will be. PRIL and SECL are leakage inductances. They will usually be

less than 1% on a well designed transformer and their variables lay

largely in how careful you wind the thing. Their values are in H. LEN

is the physical core length in inches.

How to calculate transformer AL value:

Each laminated tranformer can give different results. For audio

windings, you will need to know the AL of each transformer before

winding. For power transformers, you only need to know the turns per

volt ratio and leave the primary alone.

You can get this by measuring the secondary voltage at full load,

unwind the secondary noting the amount of turns. Divide the turns by

the secondary's voltage and you have the turns per volt ratio. Usually

between 7 and 8 for 20-30 watters. Multiply this value by 120 (or

whatever voltage the primary is rated at) and you have the approximate

amount primary turns. Usually between 800 to 100 for a 20-30 watter.

Then take a known mylar or poly (preferably with a "J" [5%] tolerance

stamp) capacitor value between 0.1 and 0.47uF and put this in series

with the primary winding. On the opposite primary winding, place a

220-470 ohm resistor. Hook up an audio signal generator with the free

capacitor end grounded and the hot lead to the resistor. Place a

high-Z AC meter between the ground and the transformer side of the

resistor. As you sweep the audio range, you will find a frequency that

gives you a dip, or null in reading. Note this frequency.

Now the math.

XL = Xc @ resonance

Xc Ohms = 1/(6.28 * CuF  * fMHz)

LuH = Xc/(6.28 * fMHz)

AL uH/turn = LuH/PRI turns

To make the formula easier to handle for transformers, divide the uH

by 1,000,000 to get Henries/turn.

What inductance do you need?

Rule of thumb - for best LF response, use four times the plate load

resistance at the lowest expected frequency. Therefore:

Tube RL = 10,000 ohms

Fmin = 15 Hz

Xpri = 40,000 @ 15 Hz

XL = 425 Henries

Hope this helps

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