Industrial Electrical Engineering and Automation Lund University, Sweden Electromagnetic Compatibility Problems in Automotive Applications Sabine Marksell

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Outline  Problem  Suggested solutions  Implementation  Experimental results  Conclusions

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Problem  Pulse Width Modulation, PWM  Long, unshielded cables  AM-band on the radio

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Suggested solutions  Shielded cable  Current return through conductor  Randomly varying switching frequency  Increasing the gate resistor

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Implementation  Shielded cables  Shield grounded in both ends  Current return through ground plane  Connectors mounted at both ends of ground plane  Randomly varying switching frequency  Switching frequency 10 kHz :250: 40 kHz  Gate resistor  3  and 330  respectively

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Experiments Set-up

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Experiments Test site

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Reference set-up  Switching frequency: 20 kHz  Gate resistor: 3   Current return through cables placed on ground  Unshielded cables Reference set-up

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Shielded cables  Switching frequency: 20 kHz  Gate resistor: 3   Current return through cables placed on ground  Shielded cables Shielded cables Reference set-up Unshielded cables

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Current return through ground plane  Switching frequency: 20 kHz  Gate resistor: 3   Current return through ground plane, cable placed on ground  Unshielded cable Current return through ground plane Reference set-up Current return through conductor

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Current return through ground plane  Switching frequency: 20 kHz  Gate resistor: 3   Current return through ground plane, cable placed 11 cm over ground  Unshielded cable Lead-in cable 11 cm above ground plane Lead-in cable placed on ground plane

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Randomly varying switching frequency, RPWM  Switching frequency: 10 kHz :250: 40 kHz  Gate resistor: 3   Current return through cables placed on ground  Unshielded cable Fix PWM (dB  A/m) Random PWM (dB  A/m) Frequency (kHz) PeakQuasi Peak PeakQuasi Peak RPWM Reference set-up fix switching frequency

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Results Using a 330  gate resistor  Switching frequency: 20 kHz  Gate resistor: 330   Current return through cables placed on ground  Unshielded cable Gate resistanceRise timeFall time 3  545 ns38 ns 330  1.42  s 94 ns 330  Reference set-up 3 

Industrial Electrical Engineering and Automation © Sabine MarksellElectromagnetic Compatibility Problems in Automotive Applications Conclusions  The current return should to the greatest possible extent be through a conductor  Varying the switching frequency gives good results in the switching frequency range  Using a high value of the gate resistance mitigates the disturbances in the higher frequency areas