[SOLVED] soft starter for single phase induction motor

[hoss3inf]

I was thinking how can i make a soft starter (and not speed controller) for a single phase induction motor, like in refrigerator compressors. does anybody know where should i start?

 

[chuckey]

Refrigerators use a NTC resistor, its high in value when cold , so the current is limited until it gets hot. Problem with thermal devices is that if the mains in interrupted for a second or so, because the device is hot, there is no current limiting when the fridge restarts.
Frank

 

[hoss3inf]

Refrigerators use a NTC resistor, its high in value when cold , so the current is limited until it gets hot. Problem with thermal devices is that if the mains in interrupted for a second or so, because the device is hot, there is no current limiting when the fridge restarts.
Frank

i didnt know about this resistor, but my problem is the shock when the compressor starts, i want it to start in low speed and increase it to reach the peak speed, what is the solution?

 

[mobinmk]

make a drive...

by varying frequency you can control the speed

u can use pwm ic like SG2535 IC or microcntroller and use igbt or mosfet for h bridge inverter.

also try with triac..

ceiling fan speed is controlled by Triac

 

[kam1787]

this is a simple circuit