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

This test is intended to measure the level of harmonics generated by the DUT in configuration "REESS charging mode coupled to the power grid" through its AC power lines in order to ensure it is compatible with residential, commercial and light industrial environments.

REESS means the rechargeable energy storage system that provides electric energy for electric propulsion of the vehicle

This CE testing must be performed per:

1. IEC 61000-3-2 for input current in charging mode ≤ 16 A per phase;
2. IEC 61000-3-12 for input current in charging mode > 16 A and ≤ 75 A per phase.

The measurements of even and odd current harmonics shall be performed up to the 40th harmonic.
The limits for single phase or three-phase DUTs in configuration "REESS charging mode coupled to the power grid" with input current ≤ 16 A per phase are given in Table 1 below:

The limits for single phase DUTs in configuration "REESS charging mode coupled to the power grid" with input current > 16 A and ≤ 75 A per phase are given in Table 2 below:

The limits for three-phase DUTs in configuration "REESS charging mode coupled to the power grid" with input current > 16 A and ≤ 75 A per phase are given in Table 3 below:

Test Setup and Procedure

• The DUT must be in configuration "REESS charging mode coupled to the power grid".
• The state of charge (SOC) of the traction battery shall be kept between 20 per cent and 80 per cent of the maximum SOC during the whole time duration of the measurement (this may lead to the measurement being split into different time slots with the need to discharge the vehicle’s traction battery before starting the next time slot).
• If the current consumption can be adjusted, then the current shall be set to at least 80 per cent of its nominal value.
• The observation time to be used for the measurements shall be as for quasi-stationary equipment as defined in Table 4 of IEC 61000-3-2.
• The test set-up for single phase DUT in configuration "REESS charging mode coupled to the power grid" is shown in Figure 1 of Appendix 1 to Annex 17, ECE Regulation 10.
• The test set-up for three-phase DUT in configuration "REESS charging mode coupled to the power grid" is shown in Figure 2 of Appendix 1 to Annex 17, ECE Regulation 10.

CISPR-25 indicates that both CE-V and CE-I must be carried out to validate an automotive electronic device.

CE-V in dBuV is measured on B+ and GND lines using the LISN port.

CE-I in dBuA is measured using a “current probe” clamped at 5 cm, then at 75 cm from DUT’s connector. The probe is clamped on the whole harness, then on each connector separately. The RF noise measured may be coupled from DUT directly as well as from wire-to-wire along the 1.7 m test harness.

CISPR 25 is not very specific about supply lines CE “redundancy”, therefore we test everything for CE-I.

Chrysler is the only OEM that specifies in CS.00054 as exception from CISPR 25 to remove from “current probe” all Supply Lines (power and ground).

CS.00054 is asking to run CE-I on all wires not tested at CE-V, however measurements are aquired only at 5 cm from DUT's connector.

2022-06-29

Christian Rosu

RF Boundary is the element of an EMC test setup that determines what part of the harness and/or peripherals is included in the RF environment and what is excluded. It may consist of, for example, ANs, BANs, filter feed-through pins, RF absorber coated wire and/or RF shielding.

RF Boundary is also an RF-test-system implementation within which circulating RF currents are confined

• to the intended path between the DUT port(s) under test and the RF-generator output port, in the case of immunity measurements (ISO 11452-2, ISO 11452-4, ISO 1145-9), and

• to the intended path between the DUT port(s) under test and the measuring apparatus input port, in the case of emissions measurement (CISPR 25),

and outside of which stray RF fields are minimized.

The boundary is maintained by insertion of BANs, shielded enclosures, and/or decoupling or filter circuits. The ideal RF boundary replicates the circuitry of the device connected to DUT in vehicle.

The standard test harness lenght for automotive EMC electronic components is (1700mm -0mm / +300mm). This 1.7m test harness runs between the DUT and the Load Simulator (Shielded Enclosure) that plays the role of RF Boundary.

If the Load Simulator enclosure does not include all DUT loads and activation/monitoring support equipment, additional support devices may be placed directly on the ground plane. The connection of additional devices to LS enclosure must be done via short wiring running on the ground plane.

Testing at subsystem level is preferable to any simulation. Whenever possible, use production intent representative loads.

Running long coax cables directly from DUT outside the chamber via SMA bulk filter panel would violate the 1.7m test harness length rule invalidating the test result. Ideally is to use Fiber Optic to exchange data with devices placed outside the test chamber.

Running long coax cables between Load Simulator and a support device placed outside the chamber is acceptable as long as the I/O line in question is not just an extension from DUT without proper RF boundary at the end of maximum 2-meter length of standard test harness.

It is critical to use the test harness length as defined by CISPR-25, ISO 11452-2, ISO 11452-4, and ISO 11452-9 to achieve valid compliance for your product. The length of the test harness as well as the grounding method (remote vs local) can result in different RF emissions level. Longer the test harness, higher RF emissions above 100 MHz due to its resonance pattern. The local grounding would show less magnitude variation across resonance peaks above 100MHz.

Christian Rosu

2022-02-20

An incorrect DUT grounding scheme can easily make the difference between compliance and non-compliance to CISPR 25 CEI limits. Sometimes we have to evaluate CEI from two modules, one used as DUT and the other one used as DUT's load (e.g. Module #1 is a PWM maker while Module #2 is an LEDs Lamp).

Christian Rosu, 2021-06-09

A few remarks on correct Load Simulator configuration for CISPR 25 Conducted Emissions Current test method.

First of all you have to show the LISN in your EMC Test Plan block diagrams. The way the LS is connected is not identical for each CISPR 25 test method. I will never use a Load Simulator unless is no other way around or I would want to turn it into a RF filter box. Examples of CEI good and bad setups are shown below:

CEI WRONG CONFIGURATION

CEI GOOD CONFIGURATION

To clarify how a PWM maker is connected:

From EMC compliance perspective the goal is to avoid as much as possible common line impedances:

Christian Rosu

2021-04-13