Lenze DDS Function library 9300 Servo - Manual (Page 20)

Function block library Lenze9300Servo.lib
Special functions
2.1.2 Supply−failure control (L_MFAIL)
2−10
L
Lenze9300Servo.lib EN 1.1
Activation of the supply−failure control
·
bFault_b TRUE = activates the supply−failure control
·
bFault_b = FALSE triggers a timing element. After elapse of the preset time in wRetriggerTime
the supply−failure control is ended/cancelled.
( ^ 2−15: fast return of supply power)
– The drive is accelerated to the speed setpoint if the restart protection is not active.
– The drive is still braked to zero speed, if the restart protection is active.
( ^ 2−14: Restart
protection)
– When restart protection is active, the drive can only be reset by bReset_b = TRUE.
Function of the supply−failure control
The drive controller gains the required energy from the rotational energy of the driven machine. The
drive is braked through the power loss of the controller and the motor. The speed deceleration ramp
is thus shorter than for an uncontrolled system (coasting drive).
After activation of the supply−failure control:
1. The DC bus voltage is controlled to the value at nDCSet_a
2. At nNOut_a an internally generated speed setpoint is output. The drive can thus be braked to
zero speed (via the speed setpoint).
– The start value for the controlled deceleration is the value at nSet_a . This input is usually
connected to MCTRL_nNAct_a (actual speed), MCTRL_nNIn_a or L_MFAIL_nNOut_a (set
speed).
– The speed deceleration ramp (and thus the brake torque) results from the moment of inertia
of the driven machine(s), the power loss of the drive (group), and the parameter settings.
Stop!
·
If a connected brake unit is activated, the drive is braked with the maximum possible torque
(I
max
). In this case, it may be necessary to adapt the parameterization (see folowing page).
·
If the power stage is not supplied, the drive cannot generate a standstill torque (important for
active loads such as hoists).