Hybrid Vehicle Generator Speed Limiting During Wheel Slip
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid electric vehicles, wheel slip events can lead to excessive generator speed when traction is regained, causing noise, vibration, and harshness (NVH) and reducing the durability of system components due to sudden increases in generator speed.
Innovation Solution
A controller is implemented to limit engine speed during a wheel slip event based on motor speed and generator speed, setting an engine speed limit to prevent generator speed from exceeding a threshold when the wheel slip event terminates, using a system comprising a transmission, internal combustion engine, planetary gearset, traction motor, generator, and traction battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vehicle operates in all-electric drive mode with the traction motor powering the drive wheels, then the vehicle can achieve good acceleration and efficiency, but the generator speed will be highest when the engine is off and the vehicle speed is limited to a maximum corresponding to maximum desired generator speed
Solution Approach 1:
The control system dynamically adjusts the engine speed parameter during wheel slip events based on motor speed and generator speed to prevent excessive generator speed when traction is regained, allowing the vehicle to operate at higher speeds without exceeding generator limits
2Productivity
If wheel slip events are allowed to occur during aggressive handling or on slippery roads, then the vehicle can maintain momentum and overcome loss of traction, but when the slipping wheel regains traction the sudden reduction in wheel speed causes corresponding increase in generator speed leading to noise, vibration, and harshness
Solution Approach 1:
The control system applies preliminary anti-action by limiting engine speed during the wheel slip event before traction is fully regained. This preemptive measure prevents the generator speed from exceeding the threshold when the wheel regains traction, thereby avoiding noise, vibration, and harshness while still allowing the vehicle to maintain momentum during the slip event
Data Source
AI summary
A method for controlling a hybrid vehicle having a transmission coupled to vehicle wheels, an internal combustion engine, a planetary gearset coupled to the engine and to a differential output shaft to drive the vehicle wheels, a traction motor coupled through gearing to the differential output shaft and the planetary gearset, a generator coupled to the planetary gearset and electrically coupled to the traction motor, a traction battery coupled to the generator and the traction motor, and at least one controller in communication with the engine, the traction motor, and the generator includes limiting engine speed in response to a wheel slip event to an engine speed limit based on motor speed and generator speed to prevent the generator speed from exceeding a corresponding threshold when the wheel slip event terminates.