dc motor speed control wiht ssr
dc motor speed control wiht ssr
(OP)
? want to make a speed control for a dc motor(3-15v),my question is 'can ? use S216SE2 (SSR, ZCD 6kv 600V 16A TUV SIP4) this one,can ? use this part to control dc device ,? look st's site but ? didn't understand (ac or dc) :)





RE: dc motor speed control wiht ssr
coupled -- SSR.
You may use the oscillation induced on inductive load
to turn off the SCR.
You can use HI voltage SCR it is just more expensive...
<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032
RE: dc motor speed control wiht ssr
RE: dc motor speed control wiht ssr
1) The 600V scr will work but it is better and more efficient to use a 50 volt device, it is more efficient because to get higher voltaged device, the dopeing is decreased resuling in "ON" voltage higher than a low voltage device, this higher "voltage X crurrent" will need also bigger heat sink to dissipate.
2) if you plan to use it on DC, use a transistor is better, there is an SCR type you can turn it OFF with gate control some have to gated on gave and off gate,but more expensive and the circuit is more complicated
3) Never use high AC (Mains supply) directly to get low voltage DC for two reasons,
A) A low voltage like 12 v is expected to be isolated (safe), this safety is due to transformer isolation.
B) if for any reason, a pulse in the wrong time turns on the scr,the high AC voltage will be rectified and supplied instead of 12V, that may cause damage
RE: dc motor speed control wiht ssr
RE: dc motor speed control wiht ssr
So, for low cost use 2 scr's and 2 diodes, use a pulse width modulation to rectify AC and get the DC you want.
Let the pulse synchronized to the zero crossing point where the scr will turn off automatically.
You may start also with light dimmers used with incandesect lamps too, then move to a more accurate circuit.
DC motors WILL change speed with loading. To prevent that a feedback is needed either from output voltage to fix it at desired level when it drops under load, or in larger motors where accurate and more torque is needed a "tacho" is used to comapre the output speed in the feedback and fix it
Maged A. Mohamed
http://magedm.freeyellow.com
http://www.magedsoft.com
RE: dc motor speed control wiht ssr
RE: dc motor speed control wiht ssr
You may see the first method in European TV's operating as line output stage (and EHT too in the horizontal output stages) like Telefunken and Grundig.
The second in older UPS systems before FET and bi polar transistors cold handle high currents in excess of 100 Amps
Maged A. Mohamed
http://magedm.freeyellow.com
http://www.magedsoft.com