The basic LEGO Power Functions motors (M, L, XL) use a fairly standard DC motor internally. The terms synchronous and asynchronous only apply to AC motors.

I'm not sure exactly where you are headed with this question, but if you are curious about whether or not PF motors can be controlled directly from a simple voltage source, the answer is yes. You don't need any complex control circuitry for the basic motors. Power is fed directly from the PF control lines (the middle two wires) to the motors.

More detailed information on the PF system can be found here:

http://www.philohome.com/pf/pf.htm

The basic LEGO Power Functions motors (M, L, XL) use a fairly standard DC motor internally. The terms synchronous and asynchronous only apply to AC motors.

I'm not sure exactly where you are headed with this question, but if you are curious about whether or not PF motors can be controlled directly from a simple voltage source, the answer is yes. You don't need any complex control circuitry for the basic motors. Power is fed directly from the PF control lines (the middle two wires) to a DC motor.

The following image shows the internals of the PF XL motor. It is electrically identical to the M motor. You can see that it has no control circuitry, and connects the control lines directly to the terminals of a basic DC motor. The only additional components are a couple of capacitors to help eliminate signal noise.

More detailed information on the PF system can be found here:

http://www.philohome.com/pf/pf.htm