Problems To Avoid - Sevcon Gen4 Applications Reference Manual


Addition of an LC filter on the keyswitch supply

Battery cable should be screened with the screen connected to the battery chassis and
controller chassis.

Motor cable should be screened with the screen connected to the motor chassis and
controller chassis.

A common mode ferrite choke for all the small signal connections will attenuate common
mode emissions

Problems to avoid

EMC is a complex subject and on a typical vehicle there are many potential radiators and
receivers. Measures taken on a vehicle to improve EMC can unintentionally make the situation
worse.

Beware of devices that are connected to the small signal wiring which have a significant
(>10nF) capacitance to vehicle chassis. The capacitance to vehicle chassis can cause
currents to flow out of the Gen4 controller along the signal wiring to the device and back to
the controller via the vehicle chassis.

When using screened cable beware of generating ground loops in which currents may be
induced or which may cause noise currents to flow via unintended paths.
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