single phase ac winder drive
babatundeawe said:
cameo_2007 said:
3 phase or single phase motor ??
there are even lot more specs you need to say like power rating,frequency,type of control(speed or direction) etc...
pls be specific with your questions.
thanks for your response.
this are my specs
1. 50hz
2. speed
3. direction
4. single phase
5. from 1kw upward
6. nominal voltage of 230 volts.
thanks for your help.
I've seen such design (PWM based) on a washing machine.
Usually you will need an 230V inverter (it generate sinusoidal output voltage with variable frequency between 10Hz and 150Hz) which is difficult for manufacturing (but not impossible even in Nigeria)
No I'm not nigerian but when I'm working for some rich people I have the feeling I am (even I'm white)... so I understand your life quite well.
For the PWM AC variation, you need a motor with two coils (one for capacitor called in folcklore as "fake phase" and another one for the 230V supply).
Changing the capacitor position will change the motor direction (ie clockwise if the capacitor is in series with coil 1, the coil1 + capacitor and coil2 is connected directly to de 230V, anticlockwise if the capacitor is connected in series with coil2 while coil1 and coil2 assembly is connected directly to 230V)
The speed can be modified if the coil connected to 230V gets a PWM instead of a permanent AC voltage. However the mechanical couple is poor and the PWM must have a small frequency (around a few Hz, less than 50Hz anyway).
I found an application note describing in figures what I said in words:
https://ww1.microchip.com/downloads/en/AppNotes/00887a.pdf
The schematic about is figure6 page4. If you change the capacitor position from starting winding to main winding you've got reversal direction. On 1KW motors, there is a small diameter wire difference between start winding and main winding. You mai use even a triphasic motor and use only two phases, but then the starting scheme is the one from figure7.
Controlling the main winding in PWM is a challenge. Solutions could be Gate Turn Off (hard to find I've guess)
https://en.wikipedia.org/wiki/Gate_turn-off_thyristor
a simple thyristor with turn off at zero load (difficult because the motor is an inductive load and you need to sense the current) or even a relay with a PWM with max frequency of 1Hz. In this last way you need a gear coupled at the motor shaft and a mechanical load at the end of the gear (looking like the rotor of a gyroscope:
https://en.wikipedia.org/wiki/Gyroscope), to keep constant the motor speed.
Success,