April 2013 1.5 New functions 37
Only CC 6xxx: Crossover Position Filter (CPF)
The CPF can be used only in dual-encoder systems with rotary and position
encoders. In such systems, the CPF is used to passively dampen certain
machine vibrations caused by the drive components in the drive chain. In
order to stabilize the position control loop in such systems with resonances,
the position signal from the position encoder, which is filtered through a
low-pass filter, and the position signal from the motor speed encoder, which
is filtered through a high-pass filter, are added and made available to the
position controller as actual position value. The filter frequency (separation
frequency) is set in MP2609 for this. The typical filter frequency values in
MP2609 are between 20 Hz and 80 Hz.
The separation frequency can be determined with the position-controller
Bode diagram of the TNCopt PC tool. The frequency at which an excessive
resonance occurs is to be selected as the value for MP2609. After the
separation frequency has been defined, the kV factor can be increased.
The block diagram shows how the crossover position filter works:
1: Crossover position filter (CPF) with high-pass (HP) and low-pass (LP)
2: Position controller
3: Speed controller
4: Current controller – power module
5: Motor
6: Machine
7: Linear encoder
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