BEV powertrain analytics from NVH to EMC topics

The interaction of electric, electronic and mechanical components defines the quality of a BEV’s powertrain. Component selection, their integration and calibration aim at meeting legal requirements for EMC and safety and competitive targets for efficiency, NVH and driving comfort. These tasks in particular need attention on electromagnetic events on the DC bus, the highpower electronics of inverters, the e-motors, and the drive shaft. Each component within this environment is defined by its electromechanical features with variabilities selected from a large set of software accessible operating parameters. Consequently, a complete powertrain and its controllers give rise to endless combinations for powertrain operation. How to understand and avoid riskful and ineffective parameter options, how to find powertrain control parameters for safe, efficient and comfortable operation? And how to find solutions within competitive development timeframes? Two examples: • A high voltage DC bus is full of AC components imposing risks for auxiliaries. • Powertrain dynamics and resonance events can compromise NVH quality and driving comfort. Such issues are addressed with extensive system simulations and gradually replacing “software components” as hardware prototypes become available. Insight into electric, electronic (E/E) and mechanical behavior is achieved with adequate sensors, signal recorders and data analytics. The focus of this paper is on E/E and NVH interrelations and signal analytics guiding the integration and optimization of powertrain modules: • E/E challenges arise within a wide frequency range: we find voltage bursts at MHz frequencies related to excitations of the harnesse’s RLC architecture. Here the task is to reduce the harnesse’s sensitivity as well as any burst excitation events. • Inverter frequency and ramp induced E/E oscillations with the safety aspect of avoiding voltage breakdown of insulation material • Current ripples related to auxiliaries on the HVDC bus must avoid overcurrents • Rotor and drive shaft dynamics must not compromise NVH quality and component durability