Lenze 8400 protec, Hardware Manual

Page: 149 / 198

Braking operation
Braking operation without additional measures
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EDS84DPS424 EN 5.0
Stopping of the ramp function generator
The "Stopping of the ramp function generator" response is set in C00175. If the brake
chopper threshold in the DC−bus connection which results from C00173 and C00174 is
exceeded, the ramp function generator is stopped.
This function is suitable for braking operations with reduced dynamics and torque
oscillations.
Inverter motor brake
During this alternative braking procedure which can be selected in C00175, the energy
conversion of the regenerative energy of the motor is achieved by dynamic
acceleration/deceleration while the ramp function generator is ramped down.
The ramp function generator is stopped during acceleration. Using a hysteresis controller,
the speed set in C00987 is added to the speed setpoint. The sign of the current actual speed
is considered in the process. The ramp function generator is also stopped if an overvoltage
occurs.
If the DC−bus voltage falls below a defined DC−bus voltage potential of the hysteresis
controller, the connected additive speed is removed and the ramp function generator is
enabled again.
The energy which results from the alternating acceleration and braking procedure due to
this switching operation is converted into heat in the motor.
In general, the following applies to the "Inverter motor brake" function:
ƒ
The regenerative energy converted in the motor can be increased and the braking
procedure can be accelerated if the additive speed setpoint is decelerated and the
corresponding filter time constant is reduced.
ƒ
There may be procedure−related torque oscillations. Mechanical vibrations can be
reduced by reducing the additive speed setpoint (C00987) or by increasing the filter
time constant.