Power Wiring
ANCA Motion
D-000129 Rev 09
77
5
5.9
Regeneration
Regeneration (Regen) refers to the process whereby a decelerating (braking) motor acts as a generator, and
kinetic energy of the associated mechanical system is regenerated back through the drive into the common DC
Bus as electrical energy. The DC Bus capacitors in the PIU, Drives & Capacitor Modules are capable of storing a
limited amount of this energy as the DC Bus voltage rises. To prevent equipment damage to the common DC
Bus, voltage rise is clamped at 806V by the PIU which connects a resistor across the common DC Bus, and
further regenerative energy is dumped into the resistor.
Regenerative Brake Resistor
5.9.1
shows the Regenerative Brake Resistor components. The PIU contains an IGBT which automatically
connects the external resistor across the DC Bus to clamp the voltage rise during regeneration, or to discharge
the DC Bus when the PIU detects a fault. All resistor energy is dissipated as heat to the environment. During
regeneration the connection of the brake resistor causes the DC Bus voltage to drop until at 786V the regen
resistor is switched off. If regeneration is still present the DC Bus voltage will rise until at 806V the regen resistor
is turned on again. This 20V hysteretic control results in the DC Bus voltage bouncing between 786V & 806V
during the regeneration cycle. However, it is important that the Brake Resistor has the appropriate resistance for
the application. If the Brake Resistor is not capable of absorbing the amount of peak regenerated power, then
the voltage will continue to rise and an overvoltage trip will occur. The selection of the appropriate resistance
value for the Brake Resistor is dependent on the application AND the PIU rating.
The regenerative Brake Resistor for the 15kW PIU can have a resistance range of between 36
Ω and 18Ω, which
results in a peak resistor power dissipation of 18kW (for 36
Ω), or 36kW (for 18Ω) when the DC Bus rises above
806V. Use a preferred value of 36
Ω unless the peak power of 18kW is insufficient for the application.
The regenerative Brake Resistor for the 24kW PIU can have a resistance of between 36
Ω and 9Ω, which results
in a peak resistor power dissipation of 18kW (for 36
Ω), or as much as 72kW (for 9Ω) when the DC Bus rises
above 806V. Use a preferred valued of 18
Ω (36kW) unless the peak power of 36kW is insufficient for the
application.
NOTE
: The Brake Resistor peak power dissipation is quite different to the continuous rms dissipation. For
example, in a given application, it is quite possible to require a peak power capability of 36kW, and have a
continuous rms resistor dissipation of 3kW. In selecting and sizing the Brake Resistor, BOTH the peak power
capability AND the continuous rms capability must be satisfied.
X1
P.E.
Regenerative Brake Resistor
AMD5x PIU
X5
AMD5x Drive(s)
Over-temperature
Switch
1
2
1
2
+DC
-DC
Figure 5-23: Regenerative Brake Resistor Components
Warning:
The regeneration resistor can reach high temperatures and should be located with adequate ventilation
and with protection against electric shock. Use cables with high temperature insulation rating. Do not allow
contaminants such as dust and oil to accumulate on the resistor.
