Efficient Networks S120 Vector control 4.1 Sensorless vector control Slvc, 6WDUW, OrvhgOrrs

Vector control 4.1 Sensorless vector control (SLVC)

I	6WDUW
	&ORVHGORRS
S
	2SHQORRS
	W

I	=HURFURVVRYHU
	&ORVHGORRS
S
	2SHQORRS
	W
	S

Figure 4-2 Start-up and passing through 0 Hz in closed-loop operation

Closed-loop operation up to approx. 1 Hz (settable via parameter p1755) and the ability to start or reverse at 0 Hz directly in closed-loop operation (settable via parameter p1750) result in the following benefits:

●No switchover required within closed-loop control (smooth operation, no dips in frequency).

●Steady-state speed-torque control is possible up to approx. 1 Hz.

Note

When the motor is started or reversed in closed-loop control at 0 Hz, it is important to take into account that a switchover is made from closed-loop to open-loop control automatically if the system remains in the 0 Hz range for too long (> 2 s or > p1758).

Permanent-magnet synchronous motors (PEM) are always started and reversed in open- loop operation. The changeover speeds are set to 10% or 5% of the rated motor speed. Changeover is not subject to any time condition (p1758 is not evaluated). Prevailing load torques (motor or regenerative) are adapted in open-loop operation, facilitating constant- torque crossover to closed-loop operation even under high static loads. Whenever the pulses are enabled, the rotor position is identified.

Drive Functions	117
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4