On-board detection of SCR system insufficient and improper reductant by magnetically coupled resonators

Selective catalytic reduction (SCR) is a standard aftertreatment technique to meet current engine emission regulations. In SCR system, AdBlue is always used as the reductant to be injected into the exhaust stream to convert NO
_x
into N
₂
. In order to ensure engine emissions compliance, insufficient or improper reductant in tank needs to be detected. In this paper, a non-contact method is proposed to detect the reductant in AdBlue tank. Two magnetic resonance coupling circuits are designed for the AdBlue level detection and AdBlue concentration detection respectively. With an adjustable source coil structure, the impedance matching can be achieved and the sensitivities of the measurements are greatly improved. The feasibility of the proposed method is validated by simulation and experimental results.