E.1: Overview; E.1.1: Differential And Common Mode Filtering; E.1.2: Description And Functional Diagram; E.1.3: Pwm Output Plot - Copley Controls Xenus XSL User Manual

Xenus Filter

E.1: Overview

The XSL-FA-01 edge filter can be used to minimize noise on the output of any Xenus amplifier.

E.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 XSL-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.

E.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 amplifiers 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 RH
inductors and a proprietary passive circuit. The inductance will provide a total of 164RH 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 RH common mode toroid that works with the cable
capacitance to earth ground to remove common mode switching noise.
Filter
Amp
J1
U
J1-4
V
J1-3
W
J1-2
Common
Mode
J1-1

E.1.3: PWM Output Plot

+HV
90%
10%
500ns
150ns
174
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Motor
J2
U
J2-4
82uH
V
J2-3
82uH
82uH W
J2-2
Differential
Case GND
J2-1
Mode
Raw PWM
Filtered
Xenus XSL User Guide
Copley Controls Corp.