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

AUTOMOTIVE ELECTRICAL TESTING - COMPONENT LEVEL

15. January 2024 05:23 by Christian in EMC/EMI, EMC TEST PLAN, Test Methods
1. Immunity to Short Circuits in the Supply Voltage Input and Load Output Lines Using 13.5 Volts on

1. Immunity to Short Circuits in the Supply Voltage Input and Load Output Lines

  • Using 13.5 Volts on all supply lines, verify proper DUT operation.
  • Connect a power supply to one supply line or load output line, set it for 13.5 volts. Then, switch it from the 13.5 volts to ground for 5 seconds.
  • Repeat the above process for all supply lines and load output lines verifying proper operation each time.

2. Immunity to Short Circuits in I/O Signal Lines

  • Using 13.5 Volts on all supply lines, verify proper DUT operation.
  • Connect a power supply to one I/O line, set it for 13.5 volts.
  • Record the steady state current. Then, switch from the 13.5 volts to ground.
  • Repeat the above process for all I/O lines verifying proper operation each time.
  • Unless the test plan specifies otherwise, maximum steady state current recorded shall be less than 200 mA.

3. Resistance to Overload

  • Fuses/Fusible Links/Circuit Breakers - short the output line to ground using the switch and measure both the current and time needed to open the circuit protection device. The current and time values and limits shall be given in the test plan. If no circuit protection device is used the DUT shall withstand a short circuit to ground for five minutes without damage to the DUT.
  • Electronic Breakers - short the output line to ground using the switch and measure both the current and the time needed to open the circuit protection device. Verify proper operation of the Electronic Breaker and DUT per test plan.

4. Supply Voltage Offset

  • Using 13.5 Volts on all supply lines, verify proper DUT operation.
  • Connect a power supply to one supply line, set it for 14.5 volts, and verify proper DUT operation. Repeat for 12.5 volts.
  • Repeat the above two steps for all battery and switched ignition supply lines in any combination.
  • Repeat entire procedure two more times for a total of three complete measurement cycles.

5. Ground Reference Offset

  • Apply a 13.5 Volt supply voltage to the DUT and verify proper operation.
  • Connect a power supply to one ground line, set it for 1 volt, and verify proper DUT operation.
  • Repeat for –1 volt.
  • Repeat the above two steps for all ground paths in any combination.
  • Repeat entire procedure two more times for a total of three complete measurement cycles.

Christian Rosu

 

Conducted Emissions – Harmonics on AC Power Lines

This test is intended to measure the level of harmonics generated by the DUT in configuration "REESS

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.

 

DUT I/O activation and monitoring during EMC validations

The main goal is to EMC validate DUT's hardware design assuming that DUT's software was developed to

The goal is to EMC validate DUT's Hardware Design assuming that DUT's Software was developed to serve the DUT's Hardware. Following a successful EMC validation, the DUT software may be subject to multipe updates and upgrades to serve the original hardware design w/o altering the outcome of overall product EMC validation.

DUT's software is used to exercise and monitor I/O lines and functions. The use of DUT production software should not be mandatory since may not be finalized prior to validation. The use of specialized DUT software is recommended since the production software may not be efficient enough to otimize the EMC testing time. The use of specialized DUT software is allowed provided that:

1) SW diagnostic timers are set to minimum detection values such that during the maximum 2-second RF exposure time all DUT response error flags are being captured and reported. Using production intent software would extend the DUT activation dwell time beyond 10 seconds such that long duation functions and/or sequential activation of various functions becomes possible.

2) DUT's state and fault conditions are reported directly via communication bus or indirectly via cyclying the outputs (e.g. changes to PWM duty cycle, monitoring LED flash rate, inadvertent status change).

3) DUT monitored data, I/O status values, analog input voltages, operating state are queried via parameter requests to ensure bi-directional communication during RF Immunity. Monitoring functional status via DUT scheduled or periodic broadcast messges is not recommended.

Module to Vehicle Interface Connector and User Interface I/O

Analog Inputs are set nominally to mid-range values and reported:
  • directly via communication bus
  • indirectly via cyclying the outputs (e.g. changes to PWM duty cycle, monitoring LED flash rate, inadvertent status change) 
Analog Outputs are set nominally to mid-range values and reported:
  • directly via Fiber Optic system
  • indirectly via loop back method (e.g. monitoring the simulated load using a DUT input)
Digital Inputs are dynalically cycled "on-off-on" during RF exposure and their state reported:
  • directly via communication bus
  • indirectly via cyclying the outputs (e.g. changes to PWM duty cycle, monitoring LED flash rate, inadvertent status change).
Digital Outputs are dynamically cycled "on-off-on" during RF exposure and their state reported:
  • directly via Fiber Optic system
  • indirectly via loop back method (e.g. monitoring the simulated load using a DUT input)
Communication Bus message loading
  • The analog properties of the bus electrical signal (e.g. Vdominant, Vrecessive, etc. must be validated during RF immunity.
  • This may require special software to decrease the data rate to be within the bandwidth limitations of analog fiber-optic transmitters.
RF I/O (Telematics, GPS, Wi-Fi, Bluetooth, RKE, TPMS) must be activated during EMC testing:
  • Received signals must be set to 3 dB above specified minimum sensitivity level.
  • The RF level is to be established with DUT installed in test chamber.
  • Bit Error Rate (BER) is the preferred metric with an acceptance threshold set by RF device specifications. 
  • BER must be monitored directly through the communication bus via parameter requests (never via scheduled, or periodic, broadcast messages).
  • Transmitted signals must be monitored by an appropriate RF receiver, again monitoring BER, acceptable threshold set by RF device specifications.

 

MCU Connector “Internal” I/O 

For such internal I/O (not connected to Vehicle I/O connector), the monitoring must be done via communication bus data or via indirect methods. Direct monitoring using attachments leads to external monitoring devices is not allowed.
  • MCU Analog Input is set to nominal operating value/condition for the specified test mode with the value reported either directly via the DUT communications bus or, indirectly through the DUT monitoring the input and changing the state of an output in a known, pre-determined manner. These functions are based on internal Printed Circuit Board (PCB) operating conditions and are not expected to
    be controlled or changed during testing; it is not necessary to force a mid-value for these inputs as with vehicle harness interface I/O.
  • Digital Input - Non-dynamic (Steady State I/O). Examples include feedback fault indication, over/under current monitoring via discrete comparator circuit, etc. The input is set to the nominal operating value/condition for the specified test mode with the value reported either directly via the DUT communications bus or, indirectly through the DUT monitoring the input and establishing the state of an output in a known, pre-determined manner. Not to include reset, address/data lines and communication between the microprocessor and electronically erasable programmable read-only memory (EEPROM), etc.
  • Digital State Input - Dynamic Cycling I/O. Requires state change between asserted to non-asserted back to asserted states during radiated immunity RF “on” exposure, reported directly by communication or indicate indirectly via output state change by detected input. Reset, address/data lines and communication between the micro and EEPROM are not included. The following MCU I/O types do not require direct monitoring since are indirectly monitored by the inherent operation of the device: Discrete outputs, Analog outputs, Internal communication bus.

Christian Rosu

Reference: Automotive OEM EMC specs

 

Measurement Instrumentation Uncertainty – (RE, CE-V,CE-I) Automotive Electronic Components

3. April 2023 14:29 by Christian in EMC/EMI, Test Methods, Uncertainty
CISPR 25 Conducted Emissions - Current Method - MU Sources CISPR 25 Conducted Emissions - Voltage -

CISPR 25 Conducted Emissions - Current Method - MU Sources

CISPR 25 Conducted Emissions - Voltage - MU Sources 

CISPR 25 Radiated Emissions - ALSE Method - MU Sources

CISPR 25 RF EMISSIONS INPUT QUANTITIES - PROBABILITY DISTRIBUTION FUNCTION

CISPR 25:2021

CISPR 25 Conducted Emissions Measurements.

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

 

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