but that does explain
.subckt diacBR100 1 24. Right click->create symbol
*Based on BR100 measured data
*Convergence problems often occur with this model
*If you have a better model please tell me
Vdummy 1 5 dc 0
Ediac 5 2 TABLE {I(Vdummy)} =
+ (-10.06m,-20.46) (-9m,-20.5) (-7.02m,-20.72) (-5.98m,-20.89)
+ (-5.05m, -21.11) (-3.26m,-21.91) (-2.15m,-22.96) (-1.6m,-23.99)
+ (-7.2n, -32.5) (-4.0n, -32) (-3.2n,-31) (-2.9n,-30) (-2.5n,-28.03)
+ (-2.3n,-25.27) (-2n,-20.15) (-1.9n,-15) (-1.8n,-7.96) (-1.5n,-1.2)
+ (0,0) (1.6n,1.24) (1.65n,5.15) (1.7n,7.91) (1.8n,10.1) (1.9n,15)
+ (2.1n,20) (2.4n,25.28) (2.9n,28.26) (3.3n,30.5) (1.6m,23.21) (2.3m,22.16)
+ (3.1m,21.44) (4.05m,20.99) (5.01m,20.65) (6.04m,20.32)
+ (6.98m,20.14) (8.09m,20.02) (9.08m,20.02) (10.12m,19.91)
.ends diacBR100
Time(seconds) | Resistance(Ohm) |
0" | 1100 |
10" | 1014 |
20" | 955 |
30" | 906 |
40" | 860 |
50" | 827 |
60" | 790 |
70" | 745 |
80" | 712 |
90" | 683 |
100" | 660 |
110" | 640 |
120" | 622 |
130" | 605 |
140" | 587 |
150" | 560 |
160" | 546 |
170" | 533 |
180" | 521 |
190" | 505 |
100" | 490 |
210" | 477 |
... However, it is assumed that the circuit element current is varying quasi-statically, that is, there is no instantaneous feedback between the current through the referenced device and the behavioural source output. ...and the macro model isn't in LTspice compatible syntax.
Yep. That's a PTC element. At 230V RMS supply, it will initially run at 189W from cold, dropping to 48W (or maybe 44W if you extrapolate to allow for the time delay from disconnecting till the first resistance reading), so with the diode in circuit that would be 22W, which matches up well enough with the iron's specs.This (pleasantly) surprises me, I expected that the manufacturer would be too...optimistic ::), as usually happens with these cheap electronics stuff.
The DIAC models from users.skynet.be/hugocoolens don't play well with LTspice.So, where can I find the correct models for the diac and the triac (BR100 & BTA12-600B)?
************************************************************************
* BR100: Diac, breakover voltage 32V, breakover current 10uA
* Pkg: Do-35, Ref: Philips, measured I-U characteristic by H. Coolens
* modelled phenomenologically as a current-dependent voltage source
* rise/fall times from parallel capacitance/serial resistance too small!
* BR100 rise time 1.5us typ. (discharge of 100nF with Ipeak=0.5A)
* DB3 rise time 2us max. (10%-90%, discharge of 100nF through 20Ohm)
* author: Detmar Welz
*
* Patched for LTspice syntax, but totally untested
************************************************************************
.subckt BR100 a b params: A=8.5 B=1u C=80m
Vdiac 1 a dc 0 ; ammeter
Cdiac 1 b 1n ; important for stability
Rdiac 1 2 1
Bdiac b 2 v={A}*atan(i(Vdiac)/{B})/i(Vdiac)**{C}
.ends BR100
************************************************************************
but don't blame me if it gives convergence errors or stalls the LTspice engine! Use with misc\DIAC.asy..lib Triac_st.lib
put the model files (.sub or .lib) in the same folder as the sim, add a .lib statement to invoke each of them and set the part no.s of the TRIAC and DIAC symbol each to the name of a model in your model files.1. I created a file BR100.sub in the same folder as my .asc file
Just a thought - I *think* that iron could be temperature controlled by a smart enough controller. If you run it from DC, the current through it can be used to calculate the element resistance, which can give you the element temperature, and, if the thermal resistance to the tip can be characterised, the bit temperature could be modelled from the excess power required to maintain the element temperature over that with the iron at rest.Sounds very interesting.
The devil would be in the details - maybe full wave rectify the mains then use a MCU to do fast PWM with a MOSFET, sensing the voltage and element current during the PWM on time. However the firmware would be non-trivial to write.
.inc BR100.sub
I don't see the problem. It isn't the output voltage that matters, its the proportion of the cycle for which the TRIAC is on.But 'proportion of the cycle that the Triac is on' and 'output Voltage'...aren't these two magnitudes proportional?
R1(ohm) | Ton (ms) | Duty cycle (D=Ton/T) |
1k | 1.42ms | 1.42ms/20ms=0.071=7.1% |
3k | 1.69ms | 1.69ms/20ms=0.0845=8.45% |
6k | 2.03ms | 2.03ms/20ms=0.1015=10.15% |
10k | 2.42ms | 2.42ms/20ms=0.121=12.1% |
15k | 2.8ms | 2.8ms/20ms=0.14=14% |
30k | 3.81ms | 3.81ms/20ms=0.1905=19.05% |
50k | 4.93ms | 4.93ms/20ms=0.2465=24.65% |
70k | 6ms | 6ms/20ms=0.3=30% |
90k | 7.19ms | 7.19ms/20ms=0.3595=35.95% |
100k | 7.94ms | 7.94ms/20ms=0.397=39.7% |
110k | 10ms | 10ms/20ms=0.5=50% |
TRIACs (and all thyristors) can have difficulty turning off when driving an inductive load including the leakage inductance of a transformer.We don 't have an inductive load here. Our load is a diode in series with a resistor (DLoad, RLoad).
A snubber network is still advisable, because even with a pure non-inductive resistive load, the TRIAC 'sees' all the wiring inductance, to the element and also back to the wall and from there to nearby appliances with a class X filter cap between L and N. Also, most mains soldering irons use a wound element so, depending on the winding structure, may not be non-inductive.TRIACs (and all thyristors) can have difficulty turning off when driving an inductive load including the leakage inductance of a transformer.We don 't have an inductive load here. Our load is a diode in series with a resistor (DLoad, RLoad).
* Parameterised three layer DIAC model
* for LTspice to match cuve of BR100/03
* without dicontinuities.
* Hand-crufted by Ian.M 22/08/2018
*
.subckt BR100 T1 T2 params: Vbr=30.5V, Ibr=30uA, Vfr=10.2V, If=10mA, Rs=1, Cp=1nF
*Precalculate consts.
.param K1={1.0141*Vbr}, K2={2.1481/Ibr}, K3={Vfr/Vbr}, K4={-7.0/If}, K5=(Vbr-Vfr)/Vbr
Rdiac N001 N002 {Rs}
Vdiac T1 N001 0 ; ammeter
Cdiac N001 T2 {Cp}
B1 N002 T2 v={K1}*tanh({K2}*I(Vdiac))*({K3}*exp({K4}*abs(I(Vdiac)))+{K5})
.ends BR100
I've tested the model under LTspice in the classic series dimmer circuit. Also, the iron in question has a PTC element (see reply #18 (https://www.eevblog.com/forum/projects/problem-with-diy-dimmer/msg1759205/#msg1759205)), so the variation of temperature with RMS voltage applied will be fairly small over a wide voltage range.So this is why this iron 's temperature stays at the same level no matter the position of the potentiometer!
The PTC element already acts to regulate the temperature (poorly as its regulating the element temperature not the bit temperature and theer is a considerable thermal resistance in between) to a predetermined temperature determined by its design. Reduce the duty cycle and thus the RMS voltage, and the element temperature drops, but that decreases the resistance, increasing the current till it reaches a balance at nearly the same power level and at only a slightly lower temperature. As there will typically be a several hundred degree difference between the tip temperature and the solder melting point, unless you have a thermocouple meter designed to measure tip temperature, you'll barely notice the temperature decrease.
Yes. When the temperature drops slightly, due to the potentiometer setting being reduced, the resistance decreases, resulting in increased power dissipation, causing it to heat up more.Also, the iron in question has a PTC element (see reply #18 (https://www.eevblog.com/forum/projects/problem-with-diy-dimmer/msg1759205/#msg1759205)), so the variation of temperature with RMS voltage applied will be fairly small over a wide voltage range.So this is why this iron 's temperature stays at the same level no matter the position of the potentiometer!
The PTC element already acts to regulate the temperature (poorly as its regulating the element temperature not the bit temperature and theer is a considerable thermal resistance in between) to a predetermined temperature determined by its design. Reduce the duty cycle and thus the RMS voltage, and the element temperature drops, but that decreases the resistance, increasing the current till it reaches a balance at nearly the same power level and at only a slightly lower temperature. As there will typically be a several hundred degree difference between the tip temperature and the solder melting point, unless you have a thermocouple meter designed to measure tip temperature, you'll barely notice the temperature decrease.
Right?
So this is why this iron 's temperature stays at the same level no matter the position of the potentiometer!If that's what its doing with a resistive load in parallel with the element + diode, or with the diode shorted out, yes.
Right?
If that's what its doing with a resistive load in parallel with the element + diode, or with the diode shorted out, yes.I have no load in parallel with the element + diode.
or if you have a large enough value pot in the dimmer to get the RMS voltage down to about 70V (on a true RMS multimeter's AC V range).How large?
If your dimmer circuit is a two terminal one (i.e. is entirely in series with the load)
If your dimmer circuit is three terminal (L, N and Load)
The BR100 DIAC holds off the voltage on C2 till it reaches its breakover voltage. It then allows C2 to discharge rapidly into the TRIAC gate, turning it on, and it stays on till the current though the load falls to zero.How can I see this on the simulation?
.model BA158 d(is=5u rs=0.1 cjo=22p bv=600 iave=1 vpk=600 type=silicon)
.step param Rshort list 1G 1Meg 1m
and you'll see what happens if the series diode in the iron is leaky..param Rshort=1G