YASKAWA A1000 Series Quick Start Manual page 89

Setting 0: Disabled
When this setting is used, the drive decelerates according to the set deceleration time. With high inertia loads or rapid
deceleration, an overvoltage (ov) fault may occur. In this case use dynamic braking options or switch to another L3-04
selection.
Setting 1: General-purpose Stall Prevention
With this setting the drive tries to decelerate within the set deceleration time. When the DC bus voltage exceeds the Stall
Prevention level, the drive pauses deceleration. Deceleration continues as soon as the DC bus voltage drops below that
level. Stall Prevention may be triggered repeatedly to avoid an overvoltage fault. The DC bus voltage level for Stall
Prevention depends on the input voltage setting E1-01.
Drive Input Voltage
200 V Class
400 V Class
Note: 1. This setting should not be used in combination with a Dynamic Braking Resistor or other dynamic braking options. If Stall
Prevention during deceleration is enabled, it will be triggered before the braking resistor option can operate.
2. This method may lengthen the total deceleration time compared to the set value. If this is not appropriate for the application consider
using a dynamic braking option.
Figure 78 illustrates the function of Stall Prevention during deceleration.
Figure 78
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 cannot 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)
Note: As the deceleration time is not constant, Intelligent Stall Prevention should not be used in applications where stopping accuracy
is a concern. Use dynamic braking options instead.
Setting 3: Stall Prevention with dynamic braking option
Enables the Stall Prevention function while using a dynamic braking resistor. Overvoltage problems in the DC bus can
occur if Stall Prevention during deceleration is disabled (L3-04) in OLV and a dynamic braking option is installed. Set
L3-04 to 3 to remedy this situation.
Setting 4: Overexcitation Deceleration 1
Overexcitation Deceleration 1 (increasing the motor flux) is faster than deceleration with no Stall Prevention (L3-04 = 0).
Setting 5: Overexcitation Deceleration 2
Overexcitation Deceleration 2 slows down the motor while trying to maintain the DC bus voltage at the level set in
parameter L3-17. By doing this, the achievable deceleration time can even be shorter than with Overexcitation
Deceleration 1.
YASKAWA ELECTRIC TOEP C710616 21C YASKAWA AC Drive - A1000 Quick Start Guide
Output Frequency
specified deceleration time
Figure 78 Stall Prevention During Deceleration
4 Start-Up Programming & Operation
Stall Prevention Level during Deceleration
377 Vdc
754 Vdc
Deceleration characteristics
when Stall Prevention was
triggered during deceleration
Time
4
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