Average-Differential-Coordinates-Based Variable Slip Ratio Control of Electrified Vehicles with Torque Vectoring Differential

These days, the vehicle dynamics control of electric vehicles (EVs) with multi-actuated architectures has been widely investigated. Such EVs have a torque vectoring differential (TVD), which can generate a torque difference between the left and right wheels. As one of TVDs, a two-motor-torque difference amplification mechanism (TDA-TVD), has been proposed. The TDA-TVD can generate a greater torque difference compared to an individual-wheel-drive (IWD) system. However, it has controllability difficulties due to its two resonance modes. Previous studies first proposed a frequency response model of the TDA-TVD and anti-vibration feedforward torque controllers based on an average-differential coordinates (ADC) transformation. Subsequently, wheel speed control (WSC) and slip ratio control (SRC) based in the ADC were presented. However, only the WSC was designed with frequency domain analysis, and the SRC was designed with manual tuning. In this study, the closed loop of the SRC of the TDA-TVD is modeled in the frequency domain, and a parameter determination method based on Nyquist plot and sensitivity function analysis of the SRC, which is the outer loop of the WSC, is suggested. Next, several SRC strategies are proposed, depending on the driver’s preference. Lastly, experimental results using a real vehicle with the TDA-TVD on slippery surfaces are shown. Newly proposed and conventional SRCs are compared. The effectiveness of the proposed strategies is analyzed and presented.