Vehicle Driveline Powershift Control Under Thermal Current Limits
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Solution Overview
Problem
Existing powertrain systems in electric vehicles experience high thermal stress and reduced service life due to high electrical currents and temperature swings during electrodynamic shifts, particularly affecting electrical machines and power electronics.
Innovation Solution
A method and control device that adjust powershifts by limiting heating through temperature and current limits, extending shift duration, reducing supporting torque, and limiting electrical phase currents to mitigate thermal stress on electrical machines and power electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high electrical currents are used to provide high torques during powershifts, then short shift durations are achieved, but heating and thermal stress increase reducing service life
Solution Approach 1:
The patent applies dynamics by continuously monitoring actual temperature and adapting the powershift execution in real-time. The control device adjusts the electrical current and torque profiles dynamically based on thermal conditions, transitioning from static high-current shifts to adaptive thermal-managed shifts that balance speed and temperature constraints.
Solution Approach 2:
The patent changes operational parameters (electrical current, torque, shift duration) based on temperature conditions. When temperature exceeds thresholds, the system modifies the powershift parameter profile to reduce current and extend duration, thereby controlling thermal stress while maintaining acceptable shift performance.
2Power
If high electrical currents flow through windings during powershifts, then high torques are provided, but losses in power electronics increase causing strong heating
Solution Approach 1:
The patent implements feedback by monitoring actual temperature and power loss conditions during powershifts. The control device uses this feedback to adjust electrical current and torque profiles, reducing current when thermal conditions indicate excessive losses, thereby optimizing the balance between power output and energy efficiency.
3Duration of action of moving object
If powershifts are executed with high torque requirements, then short shift durations are achieved, but service life of electrical machines and power electronics is reduced
Solution Approach 1:
The patent applies preliminary action by monitoring temperature conditions before executing powershifts. The control device assesses thermal state in advance and pre-adjusts the powershift profile to prevent excessive heating, thereby protecting service life while maintaining acceptable shift duration through proactive thermal management.
4Adaptability or versatility
If electrodynamic shifts are used with asymmetric electrical machine operation, then powershift functionality is achieved, but heating and thermal stress occur
Solution Approach 1:
The patent changes operational parameters (torque distribution, current profiles, shift duration) based on thermal conditions. The control device adapts the asymmetric operation parameters of electrical machines during powershifts to control thermal stress, modifying the degree of asymmetry and current magnitudes to balance powershift capability with thermal management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces thermal aging and extends the service life of electrical machines and power electronics by effectively managing heating during powershifts.
Implementation Method 1
a first electrical machine (2) and a second electrical machine (3), wherein a transmission (4) is connected between the two electrical machines (2, 3) and an output (5) on which both electrical machines act together
Implementation Method 2
High electrical currents cause high losses, especially in the power electronics of the electrical machine
Data Source
AI summary
A vehicle powertrain features a first electrical machine with first power electronics, a second electrical machine with second power electronics, and a transmission connected between the electrical machines and an output. To execute a powershift, the first and second electrical machines are operated so that one of the electrical machines is used as the main drive machine, and the other electrical machine is used for tractive force support during the execution of the powershift. When a temperature of at least one of the electrical machines and/or of at least one of the power electronics exceeds a temperature limit value, and/or when a target electric current flowing through at least one of the electrical machines and/or at least one of the power electronics exceeds a current limit value, a powershift is adapted to limit heating of the respective electrical machine and/or the respective power electronics.