Speed control

For operation of synchronous motors in the ELSM^® control mode, there are two modes, i.e. open-loop and closed-loop operation.

Open-loop operation is active when starting from idle state and below a transition speed. The transition speed is about 2% of the nominal speed. Above this transition speed value, the drive is operated in closed-loop operation.

The time during which the drive is in open-loop operation should be as short as possible, since the position of the rotor is not detected in this mode and the drive is only operated in speed-controlled mode.

If the drive is in open-loop operation, a current of at least 150% of the standstill current of the connected motor is impressed to stabilize the drive, which is why the motor heats up significantly in an idle state and at low speeds.