[PIC] How to control the 230v ac voltage with PWM duty cycle.

[saikiran@ees]

Hi,

I want to make 230V AC Light Dimmer using dspic30f5011 micro controller.My circuit image uploaded.

In the circuit diagram, at R2 i want to connect PWM uc pin.I want to use PWM duty cycle to conduct diac and triac through diac and at last the bulb will glow with required voltage.


Thanks and Regards,
M SAI KIRAN.

 

[Easyrider83]

No way. You can't use triacs with PWM.
You need zero crossing circuit to sync with AC phase and switch triac every 10ms after curresponding delay, which will adjust the power.

 

[saikiran@ees]

Thank You Easyrider83,

Please tell me,is this circuit is fine or not and one more thing is R3 and C1 are connected in the loop.Is the both end connected are phase or one end is neutral.

Thanks and Regards,
M SAI KIRAN.

 

[DanyR]

Perhaps this project can be of some help: https://www.edaboard.com/threads/345069/

 

[saikiran@ees]

Thank You DanyR,

Is the zero crossing detector is used for switch on or off the triac.If it's on,then how much delay is required.And once triac is fired and how triac will be off.


Thanks and Regards,
M SAI KIRAN

 

[DanyR]

Is the zero crossing detector is used for switch on or off the triac.If it's on,then how much delay is required.And once triac is fired and how triac will be off.

It us used to switch the triac on. The delay required is 0..10 millisecs, to be set by changing the value of Timer 0 (0..255). The higher the timer value, the smaller the time, so 255 is the lowest time (most power in the load), 0 is the highest value (more that 10 ms, the triac will never ignite). Since the timer's clock frequency is 1 Mhz, and the prescaler is set to 64, the timer0 clock is 15625 Hz, so each step costs 64 microsecs, a total of 16.4 millisecs for 256 steps (value 0).

The triac will be switched off automatically when the next zero crossing (in the triac current) occurs.