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.
