YASKAWA OYMC V1000, Programming Manual

Page: 202 / 408

1.8 L: Protection Functions
202 YASKAWA ELECTRIC SIEP C710606 10A YASKAWA AC Drive - V1000 PRELIM. Programming Manual
Figure 1.82
Figure 1.82 Stall Prevention During Deceleration
Setting 2: Intelligent Stall Prevention
With this setting the drive adjusts the deceleration rate so that the DC bus voltage is kept at
the level set in parameter L3-17. This way the shortest possible deceleration time is achieved
while the motor is protected from stalling. The deceleration time that has been selected is
disregarded, but the achievable deceleration time can not be smaller than 1/10 of the set
deceleration time.
This function uses the following parameters for adjusting the deceleration rate:
• DC bus voltage gain L3-20
• Deceleration rate calculations gain L3-21
• Inertia calculations for motor acceleration time L3-24
• Load inertia ratio L3-25
Refer to these parameters descriptions for details.
Note: As the deceleration time is not constant, Intelligent Stall Prevention should not be used in
applications where stopping accuracy is a concern. Use braking options instead.
Setting 3: Stall Prevention with Braking Option
Enables the Stall Prevention function while using a braking resistor. Use this setting if
overvoltage occurs with L3-04 disabled when using a braking resistor. This makes it
possible to reduce the deceleration time.
Setting 4: Overexcitation Braking
Enables overexcitation deceleration. Overexcitation Braking (increasing the motor flux)
shortens the deceleration time compared to deceleration with no Stall Prevention (L3-04 =
0). Repetitive or relatively long overexcitation deceleration, however, can result in motor
overheat. In such situations, either shorten the deceleration time setting or consider using a
braking resistor option. Use parameters n3-13 and n3-23 for fine-tuning this function.
Note: Because the allowable flux level for overexcitation varies based on the flux saturation
characteristics of the motor, set the proper overexcitation level by adjusting the excitation gain in
parameter n3-13. Motor characteristics and inertia of the machine influence the deceleration
time during overexcitation deceleration.
Output frequency
Deceleration characteristics
when Stall Prevention was
triggered during deceleration
Time
Specified deceleration time