Electric Machine Thermal Management via Rotor Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric machines, particularly in electric and hybrid vehicles, face overheating issues due to uneven loading, leading to reduced torque and potential destruction of power electronics when stationary and under high torque conditions.
Innovation Solution
A method and device that implement a special operating mode with cyclical value modulation to distribute power losses evenly among switch branches, using a closed-loop control device to detect operating states and modulate the rotor's movement, preventing excessive thermal loading and component destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric machine is regulated to reduce torque to avoid overheating, then the power electronics are protected from destruction, but the available torque is considerably reduced
Solution Approach 1:
The patent applies periodic action by introducing a cyclical modulation of the setpoint value that causes the rotor to oscillate between different positions. This periodic movement redistributes the thermal loading across different switch branches over time, allowing the system to maintain full torque while avoiding localized overheating through time-varying operation patterns
Solution Approach 2:
The patent implements dynamics by transitioning from a static rotor position to a dynamically oscillating rotor position through cyclical modulation. The rotor is made to move cyclically between extreme positions, creating dynamic thermal distribution patterns that prevent permanent hot spots while maintaining full power capability
2Power
If the electric machine operates at high torque while stationary, then the full torque capability is utilized, but the switch branches experience uneven loading and overheating
Solution Approach 1:
The patent uses periodic action by modulating the setpoint value cyclically to create rotor oscillations that periodically shift the thermal loading between different switch branches. This prevents any single branch from continuously bearing the full thermal burden, enabling sustained high torque operation without overheating
Solution Approach 2:
The patent applies parameter changes by introducing a cyclical modulation component to the setpoint value, which changes the rotor position parameter over time. This parameter variation transforms the thermal distribution pattern, converting a static uneven loading scenario into a dynamic balanced loading scenario across different switch branches
Data Source
AI summary
The invention relates to a method for operating an electric machine (6), and to a control device (10) that is configured to carry out the method. The method comprises a normal mode (ψnormal) and a special mode (ψspecial) in dependence on a preset target value (Mtarget), wherein the normal mode (ψnormal) comprises the steps of detecting an operating state, wherein, in the event that the detected operating state is a special state, the special mode (ψspecial) is carried out. The special mode (ψspecial) comprises the steps of modulating a cyclic value (Mcysl) on the present target value (Mtarget) and detecting the operating state, wherein, in the event that the operating state is a normal state, the normal mode (ψnormal) is carried out.