Brushless Starter Motor Temperature Control via PI Torque Regulation
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Solution Overview
Problem
Internal combustion engine starter motors face challenges in regulating temperature during low-speed/high-torque operations, leading to potential overheating and inconsistent performance during automatic restart events.
Innovation Solution
An electric starter system with a polyphase brushless starter motor and a controller using proportional-integral (PI) control logic to manage temperature by adjusting motor torque based on machine temperature, incorporating temperature sensors and a state observer for real-time temperature estimation, and pulse width modulation to maintain the motor within a safe temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the starter motor operates at low speed and high torque during automatic restart events, then the engine can be restarted, but the machine temperature increases leading to overheating and inconsistent performance
Solution Approach 1:
The system implements a temperature feedback control mechanism where temperature sensors continuously monitor the starter motor's temperature and feed this information back to the controller. The controller then adjusts the motor torque accordingly, reducing torque when temperature exceeds thresholds and restoring it when temperature is within acceptable ranges, thereby maintaining reliable operation while managing thermal conditions
Solution Approach 2:
The system dynamically adjusts the starter motor's torque output based on real-time temperature conditions. By making the torque characteristic variable rather than fixed, the system can operate at high torque when cold and reduce torque when hot, preventing overheating while ensuring reliable engine restart capability across different thermal states
2Force
If the starter motor delivers high torque during engine cranking, then the engine can be started, but the output power increases causing excessive heat generation
Solution Approach 1:
The temperature feedback control mechanism monitors starter motor temperature and adjusts torque delivery in real-time. When temperature rises above predetermined thresholds during high-torque operation, the controller automatically reduces torque to limit heat generation, and restores torque when temperature returns to acceptable levels, thereby managing energy loss while maintaining starting capability
Solution Approach 2:
The system changes the operational parameters of the starter motor based on temperature conditions. By dynamically adjusting torque (a key operational parameter) in response to temperature measurements, the system optimizes the balance between delivering sufficient force for engine starting and minimizing excessive heat generation that would lead to overheating
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
Effectively regulates the starter motor's temperature during engine start events, ensuring consistent performance and preventing overheating, thereby extending the motor's operating life and reliability.
Implementation Method 1
One or more temperature sensors may be optionally connected to the brushless starter motor, such as to a pair of phase windings and/or a lamination slot or other physical structure of the brushless starter motor. The temperature sensors output electronic signals indicative of a temperature level of the brushless starter motor
Implementation Method 2
the controller is programmed with proportional-integral (PI) control logic forming a torque control loop. Execution of temperature regulation logic in response to the requested engine start event ultimately causes the controller to determine a required starting torque of the starter motor, and to transmit a torque command to the starter motor
Implementation Method 3
pulse width modulation to maintain the motor within a safe temperature range
Data Source
AI summary
An electric starter system is usable with a powertrain having an engine with a flywheel. The starter system includes a brushless starter motor having a machine temperature, and a solenoid operable for translating a pinion gear into meshed engagement with the flywheel and the starter motor in response to a requested engine start event. A controller has temperature regulation logic that includes a proportional-integral torque control loop. Execution of a method embodied by the logic, in response to the requested engine start event when the machine temperature exceeds a first temperature, causes the controller to determine a required starting torque of the starter motor using the control loop. The controller causes the starter motor to transmit the required starting torque to the engine at a level that reduces the machine temperature below the first temperature.