dc motor control using triac and bluetooth

triac control

Hello,

I have triac circuit which I want to use to control a split phase motor. Currently I am trying to send some pulse train using a micro to switch the triac on and off but I don't seem to get anything at the output of the triac.

I am trying to based triac switching on this application notes from Toshiba. **broken link removed**

I have attached the schematic for the triac circuit.

Paul

triac speed control

Assuming 5 volt VCC, the circuit should work.

I think, that a 1 nF capacitor for the snubber is near to non existing (e. g. 47 nF is an usual dimensioning). This may be a reason for self-trigger with mains interferences (and possibly dangerous for a heater without a hardware safety thermostat), but doesn't prevent from normal operation.

Also, an inductive load as a fan may possibly not operate correctly with ZCD control. At worst case, you get trigger for one half-wave only and a DC voltage damaging the motor. For smooth switching of an (mostly) inductive load, it should be switched at maximum voltage rather than zero crossing, by the way. This avoids saturation of the core.

P.S.: I realized, that the capacitor is actually 10 nF. Better but not good. As an additional remark, in the usual circuit, I know, the capacitor also filters the MOC30xx supply, resultíng in a slightly higher dV/dt strength.

triac motor control circuit

Thanks for info. I have been trying to work on zcd for a couple of days and you are right that I get the half sine wave which seem to cause the motor to overheat but what would be the best way to control the fan speed instead of using ZCD?

triac phase control

You should use a non ZCD opto-triac instead. Or add a resistive dummy load.

how does a triac work

So if I use a non ZCD opto-triac then I would be able to use the phase control as described in Toshiba app note and also increase the capacitor to reduce the dv/dt.

For a non-zcd opto-triac, would Vishay IL440 (**broken link removed**) be suitable? It seems to have the similar characteristics.

motor control triac

I have been using MOC3021 since decades, but it needs a higher drive current. MOC3023 or IL440-6 would be O.K.

triac control circuit

Thank you very much. I will make the modification tomorrow.

Cheers
Paul

triac zcd

Just a quick question, why does zcd opto-triac behave in this fashion compare with a non-zcd opto-triac?

I am still waiting for opto from the Farnell but won't arrive until next week so I would have to test it next week.

phase control triac

The operation principle of ZCD is to allow triggering of the triac only below a voltage threshold. After a trigger occured, the triac should go to on state, normally. This happens only, if the triac holding current is exceeded, but with an inductive load, the current is initially too low and the triac goes to off state again. Cause the triac behaviout isn't exactly symmetrical, this may happen for one half-wave only.

triac cfl

i have a small que to fvm ,

i also use same ckt to switch on off the cfl , but instead of one , i connect the 4 cfl in parallel of [having chok in series] . after switch on the cfl using mc , my mc get reset .
all other appliances work fine such as fan , tube light , etc
i try moc3021 ,moc3041 , non zcd,zcd ot
what should i do ?

Added after 48 seconds:

i have a small que to fvm ,

i also use same ckt to switch on off the cfl , but instead of one , i connect the 4 cfl in parallel of [having chok in series] . after switch on the cfl using mc , my mc get reset .
all other appliances work fine such as fan , tube light , etc
i try moc3021 ,moc3041 , non zcd,zcd ot
what should i do ?

how triac works as a switch

I don't think, that this is a particular problem of the trigger circuit. Non ZCD couplers (MOC3021) are generally required, also a RC snubber should be present at the triac in any case. But the voltage spikes generated by the cfl won't cross the MOC3021, there must be another part of your circuit susceptible to interferences.

triac speed controller

I got the phase control working. The only problem is the slight humming which is a bit annoying and I guess that is the inherent nature of using phase control with triac. I decided to try another method using the zcd opto-triac which I measured from a commercial product. The method is switching on and off the triac to allow a group of sine wave to control the motor speed. To vary the speed, I have to apply different switching time to allow different sequence of sine waves. This seems to work well without any overheating but I had to trim the switch on time for the triac as it was generating a half wave. Hopefully the circuit is fine so I can finish off the rest of the software.

Cheers
Paul

triac motor speed control

WRONG !!!!!!!

triac control circuits

Manish

If you referring to my circuit, I'm afraid to tell you that the control works fine for a popular commercial ventilation product sold in NZ.

Paul

triac control capacitor motor

you mean to this

in 1 slot , 2nd slot , 3 slot
2 w , 4w , n w

i think this will work fine but , still there will be hum , and for non inductive it is power switch making on and off .

how does triac work

I am switching the triac on/off allowing different sequence of sine waves. Sorry, when I mentioned humming, I meant a buzzing noise from the triac when running at low speeds. So by using the ZCD method, the buzzing sound from the triac does not seem to occur. I have tested the ZCD method on a 85W motor and it works fine for more than 1 hour and the client seems to be happy with it but compare to the phase control, the buzzing sound was too noticeable hence the reason for it to be rejected by our client. I have measured two ventilation systems that use the two different methods. The phase control system does not have a large range of speeds compare to the ZCD method. The only problem I've found is when moving to a larger motor 115W, the motor overheats at certain speeds or sequence of sine waves. The overheating seems to happen when 50/50 on/off sequence like for example 1 on/1 off, 2on/2off, 3on/3off and so on. By changing to a non 50/50 sequence, the overheating seem to have been cured but I am awaiting for our client to test it thoroughly to determine the final outcome. By the way, what is this method of speed control called?

how triac work

The software has been approved by our client and the 115W motor does not overheat.

phase control of triac

Hi,
For motor control, Pulse Skipping System as described by ezigguart is preferable than AC Phase Angle Cutting method. Thanks.