Hybrid Powertrain Torque Control for Seamless Gear Shifts
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Solution Overview
Problem
Motor vehicles with locobox-type gearboxes face challenges in achieving a torque reduction during gear changes that is imperceptible to the user, as existing control methods often result in sub-optimal torque distribution, negatively impacting the driving experience.
Innovation Solution
A method for controlling a hybrid powertrain with two electric machines and an internal combustion engine, which involves determining torque setpoints and supervising the torque reset phase to optimize torque distribution during gear changes, ensuring minimal perceptibility to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional torque control methods are used during gear changes, then the gear change can be completed, but the torque distribution becomes sub-optimal and the torque reduction is highly perceptible to the user
Solution Approach 1:
The control method performs preliminary actions by anticipating the gear change event and preparing the torque distribution strategy in advance. The supervisory controller pre-calculates the optimal torque reset profile and coordinates the electric machines and internal combustion engine to follow this pre-planned torque delivery schedule, ensuring seamless transition during gear changes.
Solution Approach 2:
The control system dynamically adjusts torque distribution among the internal combustion engine and multiple electric machines during the gear change process. The supervisory controller continuously monitors the gear change state and modifies torque setpoints in real-time, enabling adaptive torque management that optimizes the driving experience throughout the transition phases.
2Reliability
If torque reset is performed during gear change, then optimal torque distribution can be achieved, but complex coordination between multiple actuators is required
Solution Approach 1:
A supervisory controller acts as an intermediary between the gearbox control and the torque management system. This supervisory layer receives gear change commands, determines the optimal torque reset strategy, and coordinates the torque delivery among the internal combustion engine and multiple electric machines, simplifying the overall control architecture while achieving reliable torque distribution.
Solution Approach 2:
The control method segments the gear change process into distinct phases (torque delivery phase, gear change execution, torque reset phase). Each phase has specific control objectives and torque distribution strategies. This segmentation allows the complex gear change process to be managed through simpler, phase-specific control actions.
Data Source
AI summary
Method for controlling a hybrid motor vehicle powertrain fitted with a gearbox of Locobox type. The method comprises the following steps: determining,for each electric machine and for the internal combustion engine, a torque differential defined as being the absolute value of the difference between a torque setpoint at the preceding instant and a target torque setpoint at the end of the reapplication of torque, then a Boolean variable indicating the status of the torque reapplication phase and a Boolean variable indicating the end of the torque reapplication phase for the internal combustion engine as a function of a first instant, defined as being the instant of the start of reapplication of torque and of a second instant defined as being the instant of reapplication of torque, and torque differentials for each electric machine and for the internal combustion engine, as a function of the comparison between the present instant and the first and second instants, a raw torque setpoint, an unsaturated torque setpoint, a saturated torque setpoint, and an intermediate torque setpoint are determined, then the torque setpoints for the electric machines and for the internal combustion engine are determined as a function of the determined values and variables.