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Unidrive SP Regen Installation Guide 109
Issue Number: 2 www.controltechniques.com
The value of this parameter is used for the thermal protection in regen mode.
This parameter defines the required switching frequency. The drive may automatically reduce the actual switching frequency (without changing this
parameter) if the power stage becomes too hot. The switching frequency can reduce from 12kHz to 6kHz to 3kHz, or 16kHz to 8kHz to 4kHz. An
estimate of the IGBT junction temperature is made based on the heatsink temperature and an instantaneous temperature drop using the drive output
current and switching frequency. The estimated IGBT junction temperature is displayed in Pr 7.34. If the temperature exceeds 135°C the switching
frequency is reduced if this is possible (i.e >4kHz) and this mode is enabled (see Pr 5.35 on page 109). Reducing the switching frequency reduces the
drive losses and the junction temperature displayed in Pr 7.34 also reduces. If the load condition persists the junction temperature may continue to
rise. If the temperature exceeds 145°C and the switching frequency cannot be reduced the drive will initiate an O.ht1 trip. Every 20ms the drive will
attempt to restore the switching frequency if the higher switching frequency will not take the IGBT temperature above 135°C. The following table gives
the sampling rate for different sections of the control system for different switching frequencies.
All switching frequencies can be used in regen mode with reduced losses at the higher switching frequencies.
The drive thermal protection scheme (see Pr 5.18 on page 109) reduces the switching frequency automatically when necessary to prevent the drive
from overheating. It is possible to disable this feature by setting this bit parameter to one. If the feature is disabled the drive trips immediately when
the IGBT temperature is too high.
5.07 Regen drive rated current
Drive mode Regen
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
12 1 111
Range Regen 0 to RATED_CURRENT_MAX A
Default Regen Drive rated current (Pr 11.32)
Second motor
parameter
Regen Pr 21.07
Update rate Background
5.18 Maximum switching frequency
Drive mode Regen
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
1 1 111
Range Regen 0 to 5 (3, 4, 6, 8, 12, 16 kHz)
Default Regen 0 (3 kHz)
Update rate Background
3, 6, 12kHz 4, 8, 16kHz Regen
Level 1 3 = 167µs, 6 = 83µs, 12 = 83µs 125µs Current controllers
Level 2 250µs 250µs Voltage controller
Level 3 1ms 1ms
Level 4 4ms 4ms Time critical user interface
Background N/A N/A Non-time critical user interface
5.35 Disable auto-switching frequency change
Drive mode Regen
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
111
Default Regen 0
Update rate
Background
NOTE
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