Understanding Shield Effectiveness

Shielding, or screening effectiveness, is essential to the safe operation of electric vehicles (EVs). There was a time when the noise generated by the spark plugs firing in an internal combustion engine caused an annoying buzz when listening to the AM radio. Circuit designs have since evolved, and this issue was eventually resolved, but now the issue is back. To drive the electric motors, EVs are switching over a hundred amps at 500 to 900 VDC at perhaps a 10 to 20 kHz rate. Here, the potential interference is more than an annoyance, it can affect the Automatic Driver Assistance Systems (ADAS) or other critical systems, which affects the safety of both the driver and the passengers. Controlling interference is therefore a critical requirement and understanding the shielding effectiveness of the transmission lines carrying power and data is essential to mitigating it.