Here is the circuit I am using to control the motor. L2 is meant to represent the motor and C3 is the capacitor that comes with the motor. It is a single phase AC motor found here.
This circuit is taken from LTSpice. This particular simulation is designed to simulate firing the TRIAC at 50% power, at each peak of the sine wave. In the simulation I am seeing motor current ringing which causes the TRIAC to remain on for several AC half cycles.
In the real circuit, I only start to see this behaviour at power level of 65% or more. At 65% the TRIAC fires in the right place for the first half cycle, but for the next half cycle the TRIAC doesn't turn off due to non-zero current, and so 100% of the power is delivered to the motor for that half cycle. After that I guess current does go to zero because the TRIAC turns off. Then it fires again in the next half cycle and the process repeats. So the total average power delivered to the load is not 65%, it is (65 + 100) / 2 = 82.5%.
This is not stalling the project. We can manage it. I am just wondering if any of you have any suggestions for additions to be made to the circuit to help reduce this ringing for more reliable TRIAC control of the inductive load.