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n3: High Slip Braking (HSB) and Overexcitation Braking
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High Slip Braking (V/f)
HSB works in V/f Control only and decreases the stopping time compared to normal deceleration without using dynamic
braking options. HSB reduces the output frequency in large steps to stop the motor and produce a high slip, which dissipates
the regenerative energy created from decelerating the load in the motor windings. Due to the increased temperature of the
motor windings, do not use HSB to frequently stop the motor. The duty cycle should be around 5% or lower.
Notes on Using High Slip Braking
• The set deceleration time is ignored during HSB. Use Overexcitation Deceleration 1 (L3-04 = 4) to stop the motor within a
specified time.
• Braking time varies based on the load inertia and motor characteristics.
• Enabling HSB and KEB Ride-Thru simultaneously will trigger an oPE03 error.
• HSB must be triggered by a digital input set to H1-
oo
= 68. After the HSB command is given, the drive will not restart
until the motor is completely stopped and the Run command is cycled.
• Use parameters n3-01 through n3-04 to adjust HSB.
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Overexcitation Deceleration (Induction Motors)
Increases the flux during deceleration and allows shorter deceleration time settings. Enabled by setting L3-04 to 4 or 5.
to L3-04: Stall Prevention Selection during Deceleration on page 113
.
Notes on Overexcitation Deceleration
• Frequently applying Overexcitation Deceleration raises the motor temperature because regenerative energy is mainly
dissipated as heat in the motor. In cases where frequent application is required, make sure the motor temperature does not
exceed the maximum allowable value of Overexcitation Deceleration.
• During Overexcitation Deceleration 2, Hunting Prevention in V/f Control is disabled.
• Overexcitation Deceleration can be most efficiently used in a V/f Control.
• Overexcitation Deceleration cannot be used with PM motors.
Parameter Adjustments
• Use parameters n3-13 through n3-23 to adjust Overexcitation Deceleration.
• When repetitive or long Overexcitation Deceleration causes motor overheat, lower the overexcitation gain (n3-13) and reduce
the overslip suppression current level (n3-21).
• During Overexcitation Deceleration 1 (L3-04 = 4), the drive decelerates at the active deceleration time (C1-02 or C1-04).
Set this time so no overvoltage (ov) fault occurs.
• During Overexcitation Deceleration 2 (L3-04 = 5), the drive decelerates using the active deceleration time while adjusting
the deceleration rate to keep the DC bus voltage at the level set to L3-17. The actual stopping time will be longer or shorter
than the set deceleration time depending on the motor characteristics and the load inertia. Increase the deceleration time if
overvoltage occurs (ov).
• Entering a Run command during Overexcitation Deceleration cancels overexcitation operation and the drive reaccelerates
to the specified speed.
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n3-13: Overexcitation Deceleration Gain
Multiplies a gain to the V/f pattern output value during Overexcitation Deceleration to determine the level of overexcitation.
The drive returns to the normal V/f value after the motor has stopped or when it is accelerating to the frequency reference.
No.
Name
Setting Range
Default
n3-13
Overexcitation Deceleration Gain
1.00 to 2.00
1.10
The optimum setting for n3-13 depends on the motor flux saturation characteristics.
• Gradually increase the gain to 1.25 or 1.90 to improve the braking power of Overexcitation Deceleration.
• Lower n3-13 when flux saturation characteristics cause overcurrent. A high setting sometimes causes overcurrent (oC),
motor overload (oL1), or drive overload (oL2).
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n8: PM Motor Control Tuning
These parameters adjust the control performance in the vector control modes for permanent magnet motors.
1.9 n: Special Adjustments
130
YASKAWA ELECTRIC SIEP C710636 10C Z1000U HVAC MATRIX Drive Programming Manual
