Electric Machine Control System Thermal Map Selection
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Solution Overview
Problem
Existing control methods for electric machines in vehicles, when overheating occurs, degrade energy performance by switching to non-optimized maps that delay torque reduction but compromise vehicle range and cause unpleasant jolts during acceleration or braking.
Innovation Solution
A method and system for controlling electric machines with a wound stator and rotor that dynamically select among three current maps based on temperature thresholds to minimize electrical losses, delaying the return to nominal mode only when necessary, thereby optimizing energy efficiency and reducing torque degradation while minimizing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a non-optimized map is used to delay torque reduction during overheating, then torque degradation is reduced, but energy performance and vehicle range deteriorate
Solution Approach 1:
The system dynamically switches between three different current maps (first, second, and third maps) based on real-time temperature conditions of the rotor and stator. This dynamic adaptation allows the system to optimize the balance between torque maintenance and energy efficiency according to thermal states, rather than using a fixed non-optimized map throughout the overheating condition.
Solution Approach 2:
The invention changes the electrical parameters (current distribution between stator and rotor) by selecting different maps. The first map optimizes for energy efficiency, the second map prioritizes rotor temperature control, and the third map prioritizes stator temperature control. This parameter change allows flexible trade-offs between torque maintenance and energy loss based on which component is closer to its temperature limit.
2Productivity
If a non-optimized map is used to delay torque reduction, then torque degradation is reduced, but vehicle range deteriorates
Solution Approach 1:
The system dynamically switches between three different current maps (first, second, and third maps) based on real-time temperature conditions of the rotor and stator. This dynamic adaptation allows the system to optimize the balance between torque maintenance and energy efficiency according to thermal states, rather than using a fixed non-optimized map throughout the overheating condition.
Solution Approach 2:
The invention changes the electrical parameters (current distribution between stator and rotor) by selecting different maps. The first map optimizes for energy efficiency, the second map prioritizes rotor temperature control, and the third map prioritizes stator temperature control. This parameter change allows flexible trade-offs between torque maintenance and energy loss based on which component is closer to its temperature limit.
3Ease of operation
If map switching is delayed beyond a predetermined time when returning to nominal mode, then driver discomfort is reduced, but energy efficiency deteriorates
Solution Approach 1:
The system prepares for mode transitions by using intermediate maps (second and third maps) that gradually adjust current distribution. When transitioning from overheating protection to nominal mode, the system can use the first map (optimized for energy efficiency) immediately once temperature conditions permit, rather than delaying the switch for driver comfort, because the intermediate maps serve as缓冲 during actual overheating events.
Solution Approach 2:
The system continuously monitors rotor and stator temperatures and uses this feedback to determine when to switch between maps. The switching decision is based on real-time temperature comparisons against threshold values, allowing the system to return to the energy-optimized first map as soon as thermal conditions permit, minimizing energy loss while still protecting against overheating.
Data Source
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AI summary
The invention relates to a control system (SYS) for an electric machine (ME) with a wound stator and rotor, comprising: - a first current map (CART1) minimizing electrical losses in the machine (ME), - a second current map (CART2) minimizing rotor electrical losses, - a third current map (CART3) minimizing stator electrical losses, - a means for selecting (MS) a map based on the temperatures of the rotor (Tr) and the stator (Ts), to supply the electric machine (ME), - a time-delay means (MT) of the selection means (MS), as long as a torque setpoint (T) remains above a threshold, - and a means for inhibiting (MI) the time-delay means (MT) beyond a predetermined time when the new map is the first map (CART1).