Vehicle Simulations Development to Predict Human Exposure and Magnetic Field Level in Low Frequency

Recently, the development of electric vehicles has been progressed, rapidly, to achieve Carbon neutrality by 2050. There have been increasing concerns about Electromagnetic Compatibility (EMC) performance due to increasing power for power trains of vehicles. Because same power train system expands to some vehicles, we have developed numerical simulations to predict the vehicle EMC performances. In this study, we propose a method for predicting human exposure levels and magnetic field levels in the frequency range from 1 Hz to 400 kHz, as defined in IEC 62764-1, JASO D018 and GBT 37130. These testing levels were generated by high voltage wire harness in the vehicle cabin in this study. As a result, by using the measured time characteristic of the current flowing through high voltage wire harness and the 3D simulated correlation factor between the current and the magnetic fields, we verified that the human exposure levels of the calculation results exhibited the same tendencies as the measurement result. We achieved an accuracy of approximately 4% in predicting the maximum human exposure level. We also compared the frequency characteristic of the magnetic fields. It was confirmed that we can calculate the peaks of the magnetic fields with an accuracy of approximately 5 dB, when the measurement position is near the radiated noise sources (e.g., the magnetic field probe on high voltage wire harness)

I. Introduction

Recently, the automotive industries have been striving to achieve carbon neutrality, aiming for zero CO2 emissions through the entire lifecycle of an automobile. One key initiative is the promotion of the development of electric vehicles (EVs). The powertrain system installed in EVs has several high-voltage components, including a rear inverter and motor for driving and a direct current to direct current (DCDC) converter for charging the auxiliary battery from the high-voltage battery. The harmonics of the switching frequencies impact to the vehicle EMC performance. Because these high voltage (HV) components use switching frequencies in the range of several kHz, the harmonics significantly impact to the vehicle EMC performance. This performance is attracting attention because of the recent demand for higher power train performance [1].