EMC FLEX BLOG A site dedicated to Automotive EMC Testing for Electronic Modules

Using DC Power Supply to simulate Automotive Battery for EMC testing

19. April 2021 08:23 by Christian in EMC/EMI, EMC TEST PLAN, Load Simulator
The DC Power Supply should be selected as follows:Rs (Internal Resistance) < 0.01 OHM DCZs (Inter

The DC Power Supply should be selected as follows:
Rs (Internal Resistance) < 0.01 OHM DC
Zs (Internal Impedance) = Rs for frequencies < 400 Hz.
Output Voltage:
▶ does not deviate more than 1 V from 0 to maximum load (including inrush current)
▶ recovers 63% of its maximum excursion within 100 ms
Vr (Superimposed Ripple Voltage):
▶ does not exceed 0.2 V peak-to-peak
▶ maximum frequency of 400 Hz

NOTE:
 When a battery is used for EMC testing, a charging source is needed to achieve the specified voltage reference levels.

It is important to ensure that the charging source does not affect the test.

 Linear Power Supplies are preferable vs Switching Power Supplies.

 Prior to CISPR 25 test methods ensure that the RF noise produced by the power supply is at least 6 dB lower than the limits specified in EMC Test Plan.

 If the Power Supply is located outside of the EMC test chamber, ensure thzt a bulkhead RF filter is used to prevent RF noise from entering or leaving the shielded enclosure.

 If using a HV battery, then it must be contained in a shielded enclosure.

 12V Power Supply Volatge = 13.5 (+0.5/-1.0)V

 24V Power Supply Voltage = 26 (+1.0/-2.0 V

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