# Thyristor voltage regulator with different fireing angle for each period with simulink

First of all I'm really low with EE so please, go easy on me. As home assigment we have to design Thyristor voltage regulator in simulink. It should run for 5 periods with different thyristor fireing angle for each period (30*, 60*, 90*, 120*, 150*). I managed to build it for single fireing angle with some matlab tutorials (first, second) and school book. The problem is I have no idea how to make it fire at different fireing angle each period (I mean, dynamically change the fiering angle for each period during single simulation, ex. 30* for first period, 60* for next etc.). Any tips how to do it?

The circuit and parameters: Here are parameters:

• AC Voltage source:

• Peak amplitude (V): 230
• Phase (deg): 0
• Frequency (Hz): 60
• Sample time: 0
• Measurements: None
• Pulse Generator

• Pulse type: Time based
• Time (t): Use simulation time
• Amplitude: 1
• Period (secs): 1/60
• Pulse Width (% of period): 1
• Phase delay (secs): (1/60) + (1/60) *1
• Pulse Generator1

• Pulse type: Time based
• Time (t): Use simulation time
• Amplitude: 1
• Period (secs): 1/60
• Pulse Width (% of period): 1
• Phase delay (secs): (1/60)+(1/120)+(1/160) *1
• Thyristor 1, Thryistor 2

• Resistance Ron (Ohms): 0.001
• Inductance Lon (H): 0
• Forward voltage Vf (V): 0.8
• Snubber resistance Rs (Ohms): 500
• Snubber capacitance Cs (F): 250e-9
• Series RLC Branch

• Branch type: RL
• Resistance (Ohms): 100
• Inductance (H): 0.2

*1 According to first matlab tutorial the 1/160 should give fireing angle of 135 degrees. The (1/120) is 180 degree delay. I have no idea what 1/60 is. However that math works for my case.

@edit 21.05.2015 My teacher mentoined about vector input (tho no details). How to add vector input into thyristors (so the fireing angle is changed during simulation)?

1. 1/(f)=time period of wave of frequency f
2. 1/(2*f)= time of half wave=Pi rad=180 Deg
3. if f=60 Hz then half wave period 1/(2*60)=1/120=8.33 mSe
4. 1/160=6.25 mSec
5. firing angle =6.25*180/8.33=135 deg
6. means Matlab Factor =1/((2*f)*(180/firing angle))

vtingole

• thanks for explanation of the math, however still i dont know how to change fiering angle dynamically during simulation :/ – user2475983 May 10 '15 at 18:52
• perhaps ..an increment and conditional loop would do.. – vijay ingole May 11 '15 at 19:08

Okey I figured it out. I also measure a lot of things so the circuit can be a bit messy. The repeating sequence stair with multiport switches controls the fiering angle. The parameters are:

• Repeating sequence stair:
• Vector of output values: [1 2 3 4 5]
• Sample time: 1/60 (its equal to the source's frequency but I'm not sure if that matters)

Every port of multiport switch is connected to pulse generator with different fireing angle. All but one parameters are the same among generators:

• Pulse generators:
• Amplitude: 1
• Period: 1/60
• Pulse Width: 1%
• Phase delay - the only parameter that differs:
• For generator 0,2,3,4,5: t1, t2, t3, t4, t5 (generator 0 -> t1, generator 2 -> t2 etc)
• For generator 6,1,7,8,9: 120 + t1, t2, t3, t4, t5 (generator 6 -> 120+t1, etc)

Where

• t1 = 1/720 (30* angle)
• t2 = 1/360 (60* angle)
• t3 = 1/240 (90* angle)
• t4 = 1/180 (120* angle)
• t5 = 1/144 (150* angle)

The source, thyristors and RLC branch parameters are equal to those in first post.

As you can see below the received current and voltage (the first 2 plots) change as demanded: 