DC−bus operation
Braking operation in a drive system
Basic considerations
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EDS94SPP101 EN 10.2
7.6 Braking operation in a drive system
7.6.1 Basic considerations
If the regenerative power of a drive exceeds the storage capacity of the DC bus, the
excessive energy must be consumed or dissipated. Target of the DC bus is to use the
excessive energy for other axes.
Check for all DC−bus operations if the brake power provided by the brake choppers is high
enough for the maximum regenerative power that may occur. If necessary, controllers with
an integrated brake chopper (single−axis controller instead of a multi−axis controller) must
be integrated into the drive system to increase the brake power.
If several brake choppers are used, the following conditions must be met:
ƒ The thresholds of the brake choppers must be the same for all controllers.
ƒ The brake choppers of several controllers are independent of each other. The brake
choppers are protected by changing the duty cycle or switching them off
temporarily. They are automatically switched on again.
ƒ The limiting monitorings must be considered when dimensioning the continuous
brake power for the DC bus:
– Brake chopper monitoring
– Brake resistor monitoring
ƒ The temperature monitoring of the brake resistors must lead to power−off,
otherwise the brake resistors or devices may be destroyed.
ƒ The peak brake power can be used for 0.5 s in 5−s cycles.
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