Electrical Motor Braking; Drive Dynamic Braking; Regeneration Braking; Functional Description - Kollmorgen AKD 2G-S Series Installation Manual

AKD2G-S Installation Manual, Safety 1 | 6 Technical description and data

6.6 Electrical Motor Braking

6.6.1 Drive dynamic braking

Drive Dynamic braking is a method to slow down a servo system by dissipating the mechanical energy driven by the
motor back EMF.
Drive dynamic braking is not functional safe.
The AKD2G has a built in advanced drive dynamic braking mode which operates fully in hardware. When activated,
the drive powers the motor terminals with voltages to maximize the stopping force per amount of motor current. This
advanced method forces all of the dynamic braking current to be stopping current and insures the fastest stopping
per ampere of motor terminal current.
When current is not being limited, the mechanical energy is being dissipated in the motor winding resistance.
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When current is being limited, energy is returned to the drive bus capacitors.
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The drive also limits the maximum dynamic braking motor terminal current by using the AXIS#.DBILIMIT
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parameter to insure that the drive, motor, and customer load do not see excessive currents/forces.
Whether and how the AKD2G uses dynamic drive braking depends on (AXIS#.DISMODE).

6.6.2 Regeneration braking

When the amount of returned energy from the motor builds the bus capacitor voltage up enough the drive activates
the regenerative braking circuit to start dumping the returned energy in the regen resistor (also called regenerative
resistor or brake resistor). All AKD2G offer internal resistor plus the ability to connect an external resistor depending
on the application requirements.
External regen resistors are described in the regional Accessories Manual.

6.6.2.1 Functional description

1. Individual drives, not coupled through the DC bus link circuit (+DC, -DC)
When the energy fed back from the motor has an average or peak power that exceeds the preset level for the brake
power rating, the drive generates the warning "W2010 Regen Energy Critical". If the power exceeds the set fault
level, the regenerative circuit will switch off and the drive will disable.
2. Several drives coupled through the DC bus link (+DC, -DC)
Using the built-in regenerative circuit, several drives of the same series can be operated from a common DC-bus link
(➜ # 92), without any additional measures. 90% of the combined power of all the coupled drives is always available
for peak and continuous power. If the power of the drive with the lowest switch-off threshold (resulting from
tolerances) exceeds the set fault level, the regenerative circuit will switch off on that drive.
Switch-off on over voltage: With the regenerative circuit switched off, the returned energy is not dissipated and
therefore the DC-bus link level increases. The drive reports an over-voltage fault if the DC-bus voltage threshold is
exceeded. When this happens, the drive power stage is immediately disabled and the load coasts to a stop with the
fault message "F2006 Bus Over voltage".
The ready to operate contact (terminals X21/B5-B6) is opened (➜ # 161).
Observe the regeneration time (some minutes) after full load with peak brake power.
40 Kollmorgen | kdn.kollmorgen.com | June, 2023