L3: Stall Prevention - YASKAWA GA500 Series Programming

2.9 L: Protection Functions
Does DC injection braking and short circuit braking as specified by b2-04 [DC Inject Braking Time at Stop] and b2-
13 [Short Circuit Brake Time @ Stop].
■
L2-31: KEB Start Voltage Offset Level
No.
Name
(Hex.)
L2-31 KEB Start Voltage Offset
Level
(045D)
Expert
The drive uses this formula to calculate the KEB start voltage:
KEB start voltage = L2-05 [Undervoltage Detect Level (Uv1)] + L2-31
◆

L3: Stall Prevention

L3 parameters set the Stall Prevention function and overvoltage suppression function.
■
Stall Prevention
If the load is too heavy or the acceleration and deceleration times are too short, the motor can slip too much because it
cannot work at the same rate as the frequency reference. If the motor stalls during acceleration, current increases as
the slip increases to cause an oC [Overcurrent], oL2 [Drive Overload], or oL1 [Motor Overload] and the drive will
stop. If the motor stalls during deceleration, too much regenerative power will flow back into the DC bus capacitors,
and cause the drive to fault out from ov [Overvoltage] and the drive will stop.
The stall prevention function will let the motor get to the set speed without stalling and it is not necessary for you to
change the acceleration or deceleration time settings. You can set a separate stall prevention functions for
acceleration, operating at constant speeds, and deceleration.
■
Overvoltage Suppression Function
Decreases the regenerative torque limit and increases the output frequency when the DC bus voltage increases to
prevent ov. This function can drive loads with cyclic regenerative operation, for example punch presses or other
applications with repeated crank movements. When you use this function, set L3-11 = 1 [Overvoltage Suppression
Select = Enabled].
The drive adjusts the regenerative torque limit and the output frequency during overvoltage suppression to make sure
that the DC bus voltage is not more than the level set in L3-17 [DC Bus Regulation Level].
Set these parameters as necessary when you use the overvoltage suppression function:
• L3-20 [DC Bus Voltage Adjustment Gain]
• L3-21 [OVSuppression Accel/Decel P Gain]
• L3-24 [Motor Accel Time @ Rated Torque]
• L3-25 [Load Inertia Ratio]
Note:
• When overvoltage suppression is triggered, the motor speed is more than the frequency reference. Do not use overvoltage suppression for
applications where the frequency reference and the motor speed must align.
• When you use a braking resistor, set L3-11 = 0 [Disabled].
• The overvoltage suppression function is enabled only when you operate immediately below the maximum frequency. Overvoltage
suppression does not increase the output frequency to more than the maximum frequency. Make sure that the motor and machine
specifications are correct for the application, then increase the maximum frequency.
• If there is a sudden increase to a regenerative load, ov can occur.
■
L3-01: Stall Prevention during Accel
No.
Name
(Hex.)
L3-01 Stall Prevention during
Accel
(048F)
374
V/f OLV OLV/PM AOLV/PM EZOLV OLV/PM
Sets the KEB start voltage offset.
V/f OLV OLV/PM AOLV/PM EZOLV OLV/PM
Sets the method of the Stall Prevention During Acceleration.
Description
Description
YASKAWA TOEPYAIGA5002A GA500 Programming
Default
(Range)
Determined by A1-02
(200 V Class: 0 - 100 V,400
V Class: 0 - 200 V)
Default
(Range)
1
(0 - 3)