PWM AC Motor Speed Controller

[wyl86]

Can anyone help me with this circuit.
I would like to know how this works.
I intending to try out this circuit and build it myself.
Can anyone help me explain on how this circuit works.

Thanks

 

[Grossel]

The circuit loks like a dimmer. You got a triac together with something that looks like a simple diferential amplifier circuit. But there is no sign of voltage levels or other component values.

 

[wyl86]

The circuit controls both low voltage (from 24VAC to 240VAC at 5.5A) AC motors and mains voltage (110VAC or 220VAC) loads.

R1: 4.7K resistor
R2: 3.3K resistor
R3: 680 ohm resistor
R4, R5: 22K resistors
R6: 1.5K resistor
R7: 47K (50Hz), 10K (60Hz)
R8: 100K resistor
R9: 100 ohm resistor
R10: 120 ohm resistor
R11: 68 ohm resistor
R12: 1K resistor
R13: 27 ohm resistor
R14: 390K resistor
RV1, RV2: 100K trim potentiometers
C1: 470uF electrolytic capacitor
C2: 1uF electrolytic capacitor
C3: 100nF capacitor
C5: 47nF capacitor
C6: 100nF/400V capacitor
C7: 47nF/400V capacitor
D1, D2, D7: 1N4007 diodes
D3-D6: 1N4148 diodes
T1-T3: BC547B transistors
T4: BC517 transistor
TRI1: BT137F-600 Triac
F1: 250mA slow fuse
F2: 5A slow fuse
L1: 50uH/1kHz coil
Trafo1: 2x6V/1x0.3A
Heatsink for the triac
terminal blocks (VAC, load and mains)
J1, J2 mains voltage jumpers

 

[RCinFLA]

T1 is just a half cycle 60 Hz amp.

When T2 shuts off the variable resistors and cap C2 determine the turn-on cycle delay to trigger the Triac.

T3 & T4 is a voltage comparitor with R12 & R3 providing the reference.

The Triac shuts down on zero current crossing.

L1 & C7 just EMI filter. R13 C6 is snubber across Triac to prevent false trigger by inductive load.

 

[BrownOut]

What does D7 do?

Also, doesn't appear to be any bias on Q4 collector circuit. I don't think it will actually work.

Even it it did. There should be a much easier way to do this.

 

[wyl86]

thanks for the reply..
so if there is a better to do it..
can u pls help me?
i need help in the AC Motor Speed Controller

thanks in advance..

 

[BrownOut]

The only thing you have to do is delay the trigger signal to the triac. Look at this linked webpage. This is a very simple circtuit. The resistors, capacitors and diac determine the trigger phase, and thus the power delivered to the motor.

I reached this site by goggling "triac motor control" There are lost more.



AC MOTOR CONTROL

 

[wyl86]

i need to make some changes to the AC Motor..
i need to change from 240V to 48V
can i still use the circuit from the website "AC Motor Control"?

 

[Sydney]

For an AC motor may I suggest an incandescent lamp (about 100W) as a parralel load to improve performance.