5 Motor control & motor settings
5.15 "DC-injection braking" function
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Lenze · i700 servo inverter · reference manual · DMS 3.0 EN · 06/2016 · TD06
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5.15 "DC-injection braking" function
The control modes for asynchronous motors provide the opportunity to use "DC-injection braking"
for the braking process.
DC-injection braking can be
• parameterised via bit 6 in the Lenze control word (0x2830
or 0x3030 for axis B) or
• as response to light errors. Response of the device in the event of an error
( 279)
Application cases for DC-injection braking
• DC-injection braking via bit 6 of the Lenze control word
The motor system itself can be used as an energy converter. This option is advantageous if
• a brake resistor required for absorbing the braking energy is not provided in the system. A
prerequisite for this process is that a sufficient braking torque can be reached using DC-
injection braking.
• the power of the brake chopper to be converted is limited and thus has to be used exclusively
for the main drives of the DC network. The quality of the deceleration ramp via DC-injection
braking is sufficient for auxiliary drives and unloads the brake chopper.
• a fan drive has to be braked in V/f characteristic mode.
• DC-injection braking as response to light errors
A light error can be an error of an encoder of an asynchronous machine as servo axis.
Due to the error, the quick stop function cannot be executed anymore. Optionally, the
controlled shutdown with low deceleration via DC-injection braking can be used.
Functional description
In this case, the motor control injects a DC current the amplitude of which can be set in the object
0x2B80
(or 0x3380 for axis B). For this purpose, it is required that the current control is adapted to
the corresponding motor. Setting and optimising the current controller
( 104)
0x2B80 | 0x3380 - DC-injection braking: Current
Braking current for DC-injection braking
Setting range (min. value | unit | max. value) Lenze setting
0.00 A 500.00 0.00 A
Write access CINH OSC P RX TX Scaling: 1/100 UNSIGNED_16
Note!
The r.m.s. value of the current is calculated from the time values by means of the use of
the factor "√2". This also happens in case of the field frequency 0 Hz (DC current). In case
of the DC injection braking, the r.m.s. value is thus given by the factor "√ too low in
0x2DD1:5
(or 0x35D1:5 for axis B).
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