Lenze 9400 Manual - Manual (Page 272)

Regenerative power supply modules
Rated data (devices for 400/500V mains)
Regenerative feedback with brake chopper
7

272 EDS94SPP101-7.1
7.3.4 Regenerative feedback with brake chopper
Operation in motor mode
The regenerative power supply modules provide the energy for the DC bus from which the
axis controllers are supplied. If the peak voltage of the mains is higher than the peak
voltage of the DC bus, a current flows from the mains via the DC-bus into the DC-bus
connection.
Operation in generator mode
When drives are decelerated, the excessive energy is fed into the DC bus via the controllers.
The DC-bus voltage rises.
Regenerative feedback
If the DC-bus voltage exceeds the peak value of the mains voltage, the regenerative
feedback is activated.
Up to the maximum regenerative power P
Mmax
, the controller can dissipate the energy
into the mains. If the regenerative energy and, accordingly, the DC-bus voltage continues
to rise, the ”Clamp mode” device protection is activated. This leads to an overvoltage
switch-off.
In this way, the devices are protected, but the drives coast to standstill.
Regenerative feedback with brake chopper
It is possible to use the integrated brake chopper to avoid the ”Clamp mode”. For this,
connect the brake resistor recommended as additional component.
With regenerative powers of P
gen
> P
Bron
, the brake chopper starts to dissipate part of the
energy via the brake resistor. The following formula applies: P
gen
= P
Mgen
+ P
Br
.
The following diagram shows how the regenerative power is divided between the mains
and the brake resistor.
P
BR
P
Mgen
P + P
Mmax BRmax
P
Mmax
P
BRon
P
BRmax
P
gen
P
94SSPVR050 (R)
Fig. 7-1 Power regeneration - power characteristics for deceleration in the limit range (legend: Fig. 7-2)