Multi-speed EV Power-on Upshift Oscillation Damping
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Solution Overview
Problem
Electric vehicles with multi-speed gearboxes experience oscillations in vehicle acceleration during clutch-to-clutch shifts, leading to a perceived low-quality transmission shift, particularly noticeable during power-on upshifts, which affects the comfort and drive experience of occupants.
Innovation Solution
A method of shift control that involves detecting a shift event, actuating clutches to effectuate gear ratio changes, and modulating the second electric motor to generate a torque oscillation out-of-phase with the first axle torque oscillation, thereby compensating for the oscillation and reducing overall vehicle acceleration oscillation, using calibrations correlated with accelerator pedal travel to achieve high drive shift quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a clutch-to-clutch shift is used to effectuate gear ratio change in a multi-speed gearbox, then the gear ratio change is achieved, but vehicle acceleration oscillation occurs during the shift event
Solution Approach 1:
The system applies preliminary anti-action by detecting the shift event and immediately actuating the clutch to preemptively counteract the upcoming torque oscillation. The clutch is actuated before the oscillation fully develops, preventing the harmful effect rather than merely reacting to it after occurrence.
Solution Approach 2:
The system changes parameters by modulating the second electric motor's torque output during the shift event. By dynamically adjusting the torque parameter of the second motor, the system compensates for the oscillation caused by clutch actuation, thereby stabilizing overall vehicle acceleration.
2Stability of the object's composition
If the first electric motor is modulated to compensate for the first axle torque oscillation, then the vehicle acceleration oscillation is reduced, but the overall system complexity increases
Solution Approach 1:
The second electric motor serves multiple functions: it provides drive torque to the second axle for vehicle propulsion and simultaneously acts as a compensation mechanism to counteract oscillations from the first axle. This multi-functionality reduces the need for separate compensation devices, thereby limiting the increase in system complexity.
Solution Approach 2:
The system implements feedback by detecting the shift event, actuating the clutch, and then modulating the second electric motor in response to the detected oscillation. The controller continuously monitors and adjusts the second motor's torque output based on the shift event characteristics, creating a closed-loop control system that manages complexity through intelligent regulation.
Data Source
AI summary
A method for multi-speed electric vehicle shift control for damping an acceleration oscillation of the electric vehicle. The method includes determining a percentage of accelerator pedal travel and then retrieving a clutch calibration, a first electric motor calibration, and a second electric motor calibration correlating with the determined percentage of accelerator pedal travel. The method then applies the clutch calibration in actuating a clutch-to-clutch gear ratio change, thereby generating a vibration fluctuation in a first axle, and applies the first electric motor calibration in modulating a first electric motor to dampen the vibration fluctuation. The clutch actuation and first electric motor modulation together produces a first axle torque oscillation. The method applies the second electric motor calibration in modulating the second electric motor to generate a second axle torque oscillation sufficiently out-of-phase with the first axle torque oscillation, thereby dampening the vehicle acceleration oscillation of the electric vehicle.