To achieve the aims of reducing energy consumption and CO2 emissions, Fully Electric Vehicle (FEV) needs to reach significant market shares. However, the advent of FEVs in mass production presents new challenges to automotive manufacturers due to the immaturity of the new building blocks, which can reduce FEV's safety and reliability. Among them, is the electric powertrain: i.e. electric traction motors and power electronics controller.
Another factor to be taken into account is electromagnetic interference due to the switching technology of power electronics. Furthermore, power electronics and the circulation of high currents from the battery to the motor will emit additional electromagnetic fields (EMF), including Low Frequency (LF) emissions not covered within the current automotive EMC standards.
- To develop an in-vehicle Prognostic Health Monitoring System (PHMS) for the electrical powertrain, comprising the electric traction motor and its associated power electronics. The PHMS will perform an online assessment of the powertrain condition and failsafe state, estimate its degradation level, diagnosis the type of failure and predict its Remaining Useful Life (RUL), thus enabling a condition based maintenance policy.
- To assess the possible effects of the emitted electromagnetic field (EMF) on EMC issues and the human body, and whether these fields, which may differ from those experienced in conventional cars, could exceed exposure limits. In that case, suitable reference levels will be proposed and the PHMS will also monitor the EMF in order to ensure that occupant exposure remains below acceptable limits. Additionally, design guidelines with mitigation techniques and EMC test procedures will be proposed.
Figure 1: The HEMIS project concept
The HEMIS PHMS concept is outlined in Figure 2 below. On-line assessment of the powertrain condition is based on in-vehicle sensing of suitable physical parameters, such as voltages, currents, temperatures or vibration (see Figure 1) and other relevant variables available from the vehicle communications networks, like vehicle speed. Diagnostic and prognostic algorithms developed within the project will then use the values of these physical parameters to assess the powertrain’s condition and failsafe state, and estimate the RUL of its critical components. Valuable powertrain condition information will also be provided to the maintenance service.
Figure 2: The HEMIS PHMS concept