Electric Drive Speed Setpoint Control for Smooth Clutch Torque Increase
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Solution Overview
Problem
During speed regulation phases in vehicles with electric drive machines and automated gearboxes, sudden increases in torque demand can cause a drop in the electric motor's speed and clutch engagement, leading to a jolt felt by passengers and increased electrical energy consumption.
Innovation Solution
A control method that calculates a new engine speed setpoint as the sum of the previous setpoint and a chosen positive value to compensate for the increased torque demand, allowing the electric motor's torque dynamics to adjust, preventing speed drops and clutch sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clutch is kept engaged in its slippery state to maintain driving pleasure, then the clutch may stick when torque demand suddenly increases, but if the clutch is allowed to engage fully, then driving pleasure is reduced due to jolts
Solution Approach 1:
The control method anticipates sudden torque demand increases during speed regulation phases and proactively adjusts the electric motor's speed setpoint by adding a positive value before the torque demand actually increases. This preliminary action ensures the motor is already prepared to deliver the required torque when the clutch experiences sudden load changes, preventing both clutch sticking and excessive engagement shocks, thus maintaining both driving pleasure and clutch engagement stability
Solution Approach 2:
The invention dynamically changes the speed setpoint parameter of the electric motor during speed regulation phases by adding a positive value to the previous setpoint when torque demand increases. This parameter adjustment allows the motor to operate at an optimized speed that balances clutch engagement smoothness with the ability to respond to torque demands, resolving the contradiction between driving pleasure and clutch reliability
2Reliability
If the electric motor speed is controlled to maintain a non-zero speed difference with the gearbox input shaft, then clutch sticking is prevented, but electrical energy consumption increases
Solution Approach 1:
The invention optimizes the speed setpoint parameter by adding a positive value during torque demand increases, allowing the motor to maintain the necessary speed difference for clutch non-sticking operation only when needed, rather than continuously maintaining a conservative speed margin. This reduces unnecessary electrical energy consumption while ensuring clutch reliability during critical moments
Solution Approach 2:
By proactively adjusting the speed setpoint before torque demand increases occur, the system prepares the motor to efficiently handle clutch torque variations without needing to maintain excessive speed margins throughout operation, thereby reducing overall electrical energy consumption while preventing clutch sticking
3Speed
If the electric motor torque dynamics respond quickly to sudden torque demand increases, then acceleration response is improved, but clutch engagement causes jolts felt by passengers
Solution Approach 1:
The invention adjusts the speed setpoint parameter by adding a positive value during torque demand increases, creating an optimized speed trajectory that allows the motor to deliver torque smoothly through the clutch engagement process. This parameter optimization enables fast acceleration response while minimizing the speed differential that causes jolts, thus improving acceleration without compromising passenger comfort
Solution Approach 2:
By proactively increasing the speed setpoint before torque demand spikes occur, the system prepares the motor to respond to acceleration demands in a controlled manner that maintains clutch engagement smoothness, achieving fast acceleration response without the harmful jolts that would result from reactive torque delivery
Data Source
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AI summary
A method is implemented in a vehicle comprising an electric drive unit designed to operate at a speed defined by a speed setpoint to provide engine torque, and an automated gearbox comprising at least one input shaft receiving at least a portion of the engine torque via an associated clutch. This method includes a step (10-30) in which, when an increase in the torque demand to be received by the input shaft occurs, representing a driver's desire to accelerate, during speed regulation with a previous speed setpoint, a new speed setpoint is calculated, equal to the sum of this previous speed setpoint and a chosen positive value, to continue this regulation.