EMC testing solutions for electric vehicles under real operating conditions

EMC in electric vehicles: new problems from new powertrains

The shift from internal combustion engine (ICE) vehicles to electric vehicles (EV) is not only a change in powertrain technology, but also entails a series of new electronic systems: such as HV battery packs, inverters, electric motors, ECUs, and all of which are potential sources of electromagnetic interference (EMI).

In particular, inverters are the strongest EMI-causing components due to their high switching frequencies and high voltages. When EVs use new technologies such as GaN inverters, the noise level can be 10 times higher than that of traditional IGBTs. These noises affect safety systems such as radar, cameras, and lidar sensors in ADAS, making EMC testing a mandatory requirement.

EMC testing under dynamic driving conditions

Most current EMC standards, such as CISPR 12 or CISPR 25, only require vehicles to operate at a fixed speed (e.g. 40 km/h). But in reality, electric vehicles operate continuously in many different modes: acceleration, deceleration, recharging, driving on slopes, city streets, highways, etc.

Lab measurements that do not adequately simulate these conditions will have difficulty detecting dangerous noise peaks, making the system susceptible to failure in real-world environments.

For example, the same car running at 40 km/h and 120 km/h will give completely different noise emission results, in many cases exceeding the standard threshold when entering dynamic mode.

The problem is: synchronizing test bench and measurement software

To test EMC under dynamic conditions, it is not possible to use only conventional measuring equipment. Enterprises need a test bench capable of accurately simulating the operating states of the vehicle: changing torque, increasing speed, recharging conditions, ambient temperature, etc.

However, a big challenge is how to synchronize these technical parameters with the EMC measuring software, so that the measurement takes place at the right time, at the right load conditions with the highest risk of generating interference.

Rohde & Schwarz and AVL Combined Solution: Unified EMC Test Platform

To address all of the above issues, Rohde & Schwarz has teamed up with AVL - a leading expert in simulation and dynamic testing - to develop a unified EMC test platform for real-world electric vehicle operating conditions.

System structure includes:

Rohde & Schwarz EMC system: R&S®ELEKTRA software, EMI receiver, generator, antenna, turntable

AVL PUMA test bench: simulation of motors, torque, batteries, environmental conditions, heat cabinets...

Common control interface: automatic synchronization between two software, no need for separate operation.

Outstanding features:

- Real-time synchronization of parameters: speed, torque, voltage, current, temperature...

- Detailed noise spectrum analysis according to each load condition

- Accurately determine dangerous noise frequencies and arising conditions

- Run automatic tests according to standard profiles: WLTC, NEDC, J10...

- Export full reports, easy to compare and analyze

Practical application: Full-process synchronous EMI/EMS testing

- With this system, engineers can:

- Plan EMC tests according to acceleration/deceleration cycles

- 2-way communication between PUMA and ELEKTRA to trigger measurements at the right time of high risk

- Monitor real-time noise spectrum

- Compare results between EMS modes on/off, with/without load to determine the actual impact