Motor Cables And Motor Chokes - maxon motor EPOS4 Module 50/5 Hardware Reference Manual

Motherboard Design Guide
Requirements for Components of Third-party Suppliers
4.1.4
The Module is not equipped with internal motor chokes.
The majority of motors and applications do not require additional chokes. However, in case of high sup-
ply voltage with very low terminal inductance, the ripple of the motor current can reach an unacceptably
high value. This causes the motor to heat up unnecessarily and causes instable control behavior. The
minimum terminal inductance required per phase can be calculated using the following formula:
L
Phase
L
Phase
V
CC
f
PWM
A [ ]
I
N
L
Motor
If the result of the calculation is negative, no additional chokes are necessary. Nevertheless, the use of
chokes in combination with additional filter components can be useful to reduce the emission of electro-
magnetic interference.
An additional choke must feature electromagnetic shielding, an adequate saturation current, minimal
losses, and a nominal current greater than the continuous current of the motor. The below wiring exam-
ple refers to an additional inductance of 2.2 μH or 10 μH. If a different additional inductance is required,
also the filter components must be adapted accordingly. Should you need further help with the filter
design, contact maxon Support at http://support.maxonmotor.com.
Example 1
4-74

Motor Cables and Motor Chokes

1
V

≥ -- - ⋅ CC
----------------------------- –

2 ⋅ ⋅
6 f
I
PWM N
[ ]
H
Additional external inductance per phase
V [ ]
Operating voltage +V
[ ]
Hz
Switching frequency of the power stage = 50'000 Hz
Nominal current of the motor (line 6 in the maxon catalog)
[ ]
H
Terminal inductance of the motor (line 11 in the maxon catalog)
Document ID: rel8003
© 2018 maxon motor. Subject to change without prior notice.

( ⋅ )
0.3 L

Motor
CC
Edition: May 2018 EPOS4 Module/Compact 50/5 Hardware Reference
maxon motor control
EPOS4 Positioning Controller