Testing Hybrid Technology Cars: Static and Extremely Low-Frequency Magnetic Field Measurements

Static and extremely low-frequency (ELF) magnetic fields are encountered in hybrid technology cars. These fields are mainly due to the currents flowing through the circuits, the motor, and the battery. To determine the magnetic field levels in the passenger compartment, measurements were made in all four seats at three heights (feet, chest, and head) in various types (full or mild hybrid) and models of hybrid cars. Because the magnetic flux density ^Bh changes constantly as the car travels, following the functioning sequence of the combustion engine and the electric motor, measurements were performed in four different driving conditions: stationary (idling) and traveling at 20-40 km/h, 80-120 km/h (during high-speed cruising), and over 120 km/h. The static and ELF magnetic field values were measured in the frequency range 0-32 kHz. The corresponding percentages of the 1998 International Commission on Nonionizing Radiation Protection (ICNIRP) reference values for the exposure of the general public were derived for all driving conditions. The results showed that the higher values- which instantaneously reached 78.8% of the ICNIRP's 1998 reference values for the general public-were measured in the foot area of the passenger's seats and during braking and accelerating.