• For resolver, separate twisted-pair shielded cables should be used for the primary excitation and the
sine and cosine secondary signals.
• The cable shield should be connected to the control 0V.
• Ensure that the shield does not connect the motor chassis back to the encoder ground terminal.
This is to avoid motor power cable current returning through the encoder cable shield.
CANbus
A multi-core shielded cable should be used. The inner cores must be twisted pairs. The twisted pair
should be used for CANH and CANL. Ensure that there is a common ground connection for all nodes on
the CAN bus. If there is a node on the bus which is galvanically isolated from the Dragon8 controller
then the CAN ground on this node must be connected to the Dragon8 controller control 0V. The cable
shield should be connected to the control 0V terminal at the Dragon8 controller
Additional measures
Where it has not been possible to meet the required EMC specifications using the standard measures
listed above it may be necessary to use one or more of the following measures:-
• Use of shielded cable for all control connections
• Use of a Faraday cage around the controller and motor
• Addition of an LC filter on the keyswitch supply
• 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 recievers.
Measures taken on a vehicle to improve EMC can unitentionally 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 Dragon8 controller along the signal wiring to the device and back to the controller via the
vehicle chassis.
• When using shielded 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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