Vehicle Motor Temperature Control via Dynamic Current Adjustment
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Solution Overview
Problem
The torque output of electric motors in vehicles varies with the temperatures of their components, such as the rotor, stator, IGBT, and inverter diode, leading to inefficiencies and potential overheating, which existing control systems fail to adequately address.
Innovation Solution
A temperature-based control system that determines a maximum stator current and torque output by considering the temperatures of these components, using a temperature module to adjust d-axis and q-axis current commands, and a switching control module to manage power application to the electric motor, thereby optimizing torque production and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric motor operates at high torque output, then productivity is improved, but temperature of components increases leading to overheating and reliability degradation
Solution Approach 1:
The control system continuously monitors temperatures of multiple components (stator, rotor, IGBT, inverter diode) and uses this feedback to dynamically adjust the maximum stator current and torque output. This closed-loop temperature-based control prevents overheating while maximizing torque production within safe thermal limits.
Solution Approach 2:
The system dynamically adjusts operating parameters (stator current, torque output) based on real-time temperature conditions. The maximum stator current is not fixed but varies according to the thermal state of components, allowing the motor to operate at higher torque when cool and reduce torque when temperatures approach critical levels.
2Power
If the electric motor operates at high stator current, then torque output is improved, but loss of energy increases due to resistive heating
Solution Approach 1:
The system changes the operating parameter (stator current) based on temperature conditions. By adjusting the maximum stator current according to component temperatures, the system optimizes the balance between torque production and resistive heating losses, preventing excessive energy loss while maintaining required torque output.
3Device complexity
If existing control systems are used without temperature-based adjustment, then device complexity is reduced, but reliability decreases due to inadequate overheating prevention
Solution Approach 1:
The temperature control module integrates multiple temperature monitoring functions and control operations into a single unified system. It simultaneously manages stator current limiting, torque adjustment, and protection for multiple components (motor and inverter), providing comprehensive overheating prevention without requiring separate complex control systems for each function.
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 solution maximizes torque output while preventing motor or inverter overheating by dynamically adjusting current commands based on component temperatures, enhancing the efficiency and reliability of electric motor performance in vehicles.
Implementation Method 1
A temperature module is configured to, based on a motor torque request for an electric motor of the vehicle, (i) determine a plurality of stator current values based on a plurality of temperatures
Implementation Method 2
A switching control module is configured to, based on the d-axis current adjustment and the q-axis current adjustment, control switching of an inverter module and apply power to stator windings of the electric motor from an energy storage device
Data Source
AI summary
An electric motor control system of a vehicle includes a temperature module configured to, based on a motor torque request, (i) determine a plurality of stator current values based on a plurality of temperatures and (ii) generate a maximum stator current based on a lowest value of the plurality of stator current values. A torque module configured to, based on the maximum stator current, the motor torque request, and a maximum allowable flux, generate a maximum torque output. A current command module configured to, based on a speed of a rotor of the electric motor and the maximum torque output, generate a d-axis current adjustment and a q-axis current adjustment. A switching control module configured to, based on the d- and q-axis current adjustments, control switching of an inverter module and apply power to stator windings of the electric motor from an energy storage device.