YASKAWA A1000 Series Technical Manual page 260

5.8 L: Protection Functions
Overvoltage Suppression Function
■
This function suppresses overvoltage faults by decreasing the regenerative torque limit and slightly increasing the output
frequency when the DC bus voltage rises. It can be used to drive loads with cyclic regenerative operation, such as a
punch press or other applications that involve repetitive crank movements.
The regenerative torque limit and the output frequency are adjusted during ov suppression so that the DC bus voltage
does not exceed the level set in parameter L3-17. In addition to the parameters explained below, ov suppression also uses
these settings for frequency adjustment:
• 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: 1. The motor speed will exceed the frequency reference when overvoltage suppression is triggered. Consequently, overvoltage
suppression is not appropriate in applications that require a perfect match between the frequency reference and the motor speed.
2. Disable overvoltage suppression when using a braking resistor.
3. Overvoltage may still occur if there is a sudden increase to a regenerative load.
4. This function is enabled only when operating just below the maximum frequency. Overvoltage suppression does not increase the
output frequency beyond the maximum frequency. If this is required by the application, increase the maximum frequency and change
the base frequency setting.
L3-11: Overvoltage Suppression Function Selection
■
Enables or disables the overvoltage suppression function.
No.
L3-11
Setting 0: Disabled
The regenerative torque limit and the output frequency are not adjusted. A regenerative load may trip the drive with an
overvoltage fault. Use this setting if dynamic braking options are installed.
Setting 1: Enabled
When the DC bus voltage rises due to regenerative load, an overvoltage fault is prevented by decreasing the regenerative
torque limit and increasing the output frequency.
■ L3-17: Target DC Bus Voltage for Overvoltage Suppression and Stall Prevention
Sets the target DC bus voltage target level used by the overvoltage suppression function (L3-11 = 1), Intelligent Stall
Prevention during deceleration (L3-04 = 2).
No.
L3-17 Target DC Bus Voltage for Overvoltage Suppression and Stall Prevention
<1> Values are for 200 V class drives and must be doubled for 400 V class drives.
<2> This value is initialized when E1-01 is changed.
L3-20: DC Bus Voltage Adjustment Gain
■
Determines the proportional gain used by overvoltage suppression (L3-11 = 1), Single Drive KEB 2 (L2-29 = 1), KEB
Ride Thru 2 (H1- = 7A or 7B) and Intelligent Stall Prevention during deceleration (L3-04 = 2) in order to control the
DC bus voltage.
No.
L3-20
Adjustment for Single Drive KEB 2 (L2-29 = 1) and Intelligent Stall Prevention During Deceleration
• Increase this setting slowly in steps of 0.1 if overvoltage or undervoltage occurs at the beginning of deceleration.
• If this setting is too high, then a fair amount of speed or torque ripple can result.
Adjustment for Overvoltage Suppression
• Increase this setting slowly in steps of 0.1 if overvoltage suppression is enabled (L3-11 = 1) and a sudden increase in a
regenerative load results in an overvoltage (ov) fault.
260
Name
Overvoltage Suppression Function Selection
Name
Name
DC Bus Voltage Adjustment Gain
YASKAWA ELECTRIC SIEP C710616 27C YASKAWA AC Drive A1000 Technical Manual
Setting Range
0 or 1
Setting Range
150 to 400 Vdc 370 Vdc
<1>
Setting Range
0.00 to 5.00 Determined by A1-02
Default
0
Default
<1> <2>
Default