Hollow Stator Windings for Direct Battery Coolant Heating
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Solution Overview
Problem
Existing automotive systems for heating vehicle batteries are inefficient, leading to significant heat loss and reduced effectiveness in transferring heat from the electric machine to the traction battery, particularly with Lithium Iron Phosphate (LFP) batteries.
Innovation Solution
The system employs hollow windings with coolant inside the stator slots of an electric machine, where a pump drives the coolant to absorb heat from the motor, and a control valve selectively directs the coolant between the motor windings and the battery coolant circuit based on temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant is directed through a complex coolant hose system and heat exchangers to heat the battery, then the battery can be heated, but heat loss increases and heating effectiveness decreases
Solution Approach 1:
The patent extracts the coolant flow path from the complex external hose system and heat exchangers, and redirects it directly through the electric machine windings to the battery, eliminating unnecessary intermediate components and reducing heat loss in the process
Solution Approach 2:
The patent merges the cooling function for the electric machine and the heating function for the battery into a single integrated coolant flow path, allowing heat transfer to occur directly as coolant flows from the motor windings to the battery without requiring separate systems
2Temperature
If a complex coolant system with multiple heat exchangers is used to transfer heat from electric machine to battery, then heat transfer can be achieved, but device complexity increases
Solution Approach 1:
The patent removes unnecessary intermediate heat exchangers and complex hose systems from the coolant path, retaining only the essential direct flow path from electric machine to battery, thereby simplifying the overall system architecture
Solution Approach 2:
The patent incorporates thermal management functionality directly into the electric machine structure during manufacturing, with coolant channels pre-integrated into the stator and rotor, eliminating the need for separate after-market heat exchanger installations
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
This configuration reduces heat loss at the motor, enhances cooling efficiency of the motor windings, and provides a more direct and effective heat transfer path from the electric machine to the battery, improving overall system performance and torque densities.
Implementation Method 1
A pump drives coolant through the hollow wires to cool the electric machine
Implementation Method 2
The controller, based on a temperature of a battery, selectively directs coolant through a coolant circuit for the battery and hollow windings of an electric machine
Data Source
AI summary
Responsive to a temperature of a battery being less than a threshold temperature, a controller directs coolant from hollow wires wound within slots of a stator to a coolant circuit for the battery. Responsive to the temperature being greater than the threshold temperature, the controller directs the coolant from the hollow wires back to the hollow wires while bypassing the coolant circuit.