User Manual V 1-4.XX User guide

Control Block Diagrams B-21
Understanding the Bus Regulator
The bus regulator limits the maximum bus voltage for systems that do
not have brake or regen (regenerative) capabilities.
Refer to Chapter 9, Applications, for more information on using the
bus regulator for braking.
Understanding the Power Limits
The power limits let you set limits on the maximum power limits in
the positive and negative directions. Without these limits, you could
receive a Bus Overvoltage Trip, which is a hardware fault.
The power limits first perform a full wave rectify to separate the input
from the bus regulator into a positive value and a negative value. Once
these values are separated, the minimum/maximum selection
functions compare the values from the full wave rectify with the value
of Autotune Torque (parameter 164) and the value of either Pos
Torque Lim (parameter 74) or Neg Torque Lim (parameter 75) to
determine which value is closest to zero (the most conservative
value). The drive then passes the values to the torque limit function.
Understanding the Torque Limit
The torque limit function uses the values it receives from the power
limit function.
If a value is limiting the torque or current in either the positive or
negative direction, a bit is set in Torque Limit Sts (parameter 87).
file:
Application
group:
Bus Control
file:
Control
group:
Control Limits
If bit 10 of
Bus/Brake Opts
(parameter 13) is:
Then:
Set (1) to indicate that the
system has a brake or regen
capability
The drive uses the value of Regen Power Lim
(parameter 76).
Clear (0) to indicate that the
system does not have a
brake or regen capability
The bus regulator limits the maximum bus voltage by
automatically adjusting the value of Regen Power Lim.
In this case, you should use a default value of -25%. If
the drive system has significant losses, you can
decrease this value until bus voltage faults occur.
file:
Autotune
group:
Autotune Setup
file:
Control
group:
Control Limits
If Min Flux Level
(parameter 71) is:
The values
are:
Not 100% Passed directly to the torque limit selector.
Set to100%
Multiplied by 1/flux and Motor Flux % (parameter 88) is
applied before the values are passed to the torque limit
selector.