User guide

Xenus Plus User Guide Xenus Plus Filter
Copley Controls 140
D.1: Overview
The XTL-FA-01 edge filter can be used to minimize noise on the output of any Xenus Plus drive.
D.1.1: Differential and Common Mode Filtering
Most noise is capacitively coupled from the motor power cable to neighboring cables. To minimize
this noise, the XTL-FA-01 edge filter uses both differential edge filtering and common mode
filtering. Differential edge filtering reduces the high frequency component of the PWM signal, thus
producing a signal with less energy that can be coupled during transmission. Common mode
filtering reduces the unnecessary common mode noise generated by PWM signals.
D.1.2: Description and Functional Diagram
The differential filter increases the rise time by at least a factor of 3, substantially reducing noise in
the system. Copley Controls drives typically have a 150 ns rise-time (high frequency component in
the MHz range). Thus, the edge filter can increase rise time to 500 ns, reducing the high frequency
noise emissions by the square law. The differential filter is designed with 82 µH inductors and a
proprietary passive circuit. The inductance will provide a total of 164µH in series with the load,
helping to reduce ripple current. This brings low inductance motors into the required range.
The common mode filter is designed with a 220 µH common mode toroid that works with the cable
capacitance to earth ground to remove common mode switching noise.
D.1.3: PWM Output Plot
Amp
Filter
Motor
U
V
W
J1
J1-4
J1-3
J1-2
J1-1
Common
Mode
82uH
82uH
82uH
Differential
Mode
J2
J2-4
J2-3
J2-2
J2-1
U
V
W
Case GND
+HV
500ns
10%
90%
Raw PWM
Filtered
150ns