Drivability Optimization of Electric Vehicle Drivetrains for Brake Blending Maneuvers

Abstract

Electric vehicle drivetrains are considered a way to reduce greenhouse gas emissions from road traffic. The use of electric drives in automotive vehicles offers advantages, such as the potential to recover energy during braking (regenerative braking). The limitation of the maximum air gap torque of the vehicle drive machine by several factors requires a temporary standalone or simultaneous use of the conventional vehicle wheel brake. In several studies, it is shown that during braking operations, the drive machine and the vehicle wheel brake can induce torsional oscillations in the drivetrain, which have a negative influence on the driving comfort and lead to a high mechanical load. To reduce these oscillations, the simultaneous use of an active anti-jerk control is necessary. Due to the problem of oscillation excitations caused by a brake intervention, the used drivability function (integrated prefilter, anti-jerk control) is investigated and optimized with regard to brake blending maneuvers and the effectiveness for damping torsional oscillations. Therefore, the dynamics of the drivetrain are adapted to the dynamics of the braking system using the prefilter, which leads to precise fulfilment of the driver’s braking desire, even during dynamic brake blending maneuvers. All investigations are carried out with a hardware-in-the-loop test bench to create reproducible results.

Detection of Torque Security Problems Based on the Torsion of Side Shafts in Electrified Vehicles

“…The experimental investigations in this research are carried out with the use of a HiL test bench, which was also used in [25][26][27][28][29].…”

“…For the close-to-reality reproduction of the oscillation behavior of the drivetrain, a series-produced vehicle side shaft with typically torsional stiffness is integrated into the HiL test bench [30]. In [25][26][27][28][29]31], it is proven that the oscillation behavior of the HiL test bench in combination with the HiL simulation model corresponds to the oscillation behavior of a real electrified vehicle drive system.…”

“…As mentioned above, the drivability function with integrated anti-jerk control described in [25,28] is used to reduce the jerk oscillations that typically occur in the drivetrain. The drivability function modifies the desired torque of the vehicle's drive machine M DrMD , as shown in Figure 2.…”

“…The drivability function modifies the desired torque of the vehicle's drive machine M DrMD , as shown in Figure 2. The structure of the drivability function is described and developed in [25] and optimized in [28]. The drivability function consists of the prefilter and anti-jerk control subsystems.…”

“…The desired drivetrain torque M DrTrnD is used as the input variable. According to the explanations in [25,28], the prefilter can be derived from a simplified system model for the vehicle side shaft torque. Additionally, pole-zero compensation is performed.…”