YASKAWA GA700 Technical Manual page 847

Drive Input Voltage
200 V class
400 V class
The following figure illustrates the function of Stall Prevention during deceleration.
2 : Automatic Decel Reduction
The drive adjusts the deceleration rate so the DC bus voltage is kept at the level set to L3-17 [DC Bus Reg Level].
This produces the shortest possible deceleration time while protecting the motor from stalling. The selected
deceleration time is disregarded and 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:
• L3-20 [DC Bus Voltage Adjustment Gain]
• L3-21 [Accel/Decel Rate Calculate Gain]
• L3-24 [Motor Accel Time for Inertia Cal]
• L3-25 [Load Inertia Ratio]
Note:
The deceleration time is not constant. Use dynamic braking options instead and set L3-04 t= 0 in applications where stopping accuracy
is a concern. Set L3-04 = 3 if an ov occurs.
3 : General Purpose w/ DB resistor
This setting requires a dynamic braking resistor. Enables the Stall Prevention function while using a dynamic
braking resistor.
4 : Overexcitation/High Flux
Enables Overexcitation Deceleration 1. Enables deceleration times shorter than that when L3-04 = 0.
Note:
• A long overexcitation time and frequent repetitions of deceleration can trigger oL1 [Motor Overload]. If an oL1 is detected, either
shorten the deceleration time or install a braking resistor to the drive.
• The deceleration time during Overexcitation Deceleration varies depending on the motor characteristics and machine inertia. Adjust the
levels set by n3-13 [Overexcitation Deceleration Gain] and n3-23 [Overexcitation Operation Select]. Refer to "n3: High Slip Braking
(HSB), Overexcitation Deceleration" for details.
5 : Overexcitation/High Flux 2
Enables Overexcitation/High Flux 2. This function shortens the achievable deceleration time more than by using
Overexcitation/High Flux.
The drive slows down the motor while trying to maintain the DC bus voltage at the level set to L3-17.
Lower the values set in n3-13 and n3-21 if an oL1 is detected. Increase the value set in C1-02, C1-04, C1-06, and
C1-08 [Deceleration Time] if an ov is detected.
Note:
• While Overexcitation/High Flux 2 is operating, both Hunting Prevention in V/f Control and Speed Control using torque limit in OLV
Control are disabled.
• Refer to "n3: High Slip Braking (HSB), Overexcitation Deceleration" for details.
YASKAWA ELECTRIC SIEP C710617 01B YASKAWA AC Drive GA700 Technical Manual
Table 11.57 Decel Stall Prevention Level
377 V
754 V
Figure 11.131 Decel Stall Prevention Operation
11.9 L: Protection Function
Decel Stall Prevention Level
11
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