Brushless Electric Starter Motor Torque Control
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Solution Overview
Problem
Conventional brushed electric starters in vehicle propulsion systems face issues such as motor degradation due to physical contact wear, limited torque near the upper speed range, and sequential solenoid actuation leading to time delays and voltage drops, which affect engine restart efficiency and responsiveness.
Innovation Solution
A brushless electric machine with a pinion gear and a controller assembly that converts direct current into multi-phase alternating current using pulse width modulation, allowing for rapid engine restarts and reduced voltage sag, eliminating the need for supplemental power sources and boosting means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brushed electric starter is used, then the system structure is simpler and cost is lower, but the motor degrades over time due to physical contact wear
Solution Approach 1:
The patent replaces the mechanical brush contact system with a brushless electric machine that uses electromagnetic fields to transfer power. This eliminates physical wear between moving parts, significantly improving motor durability and reliability while reducing maintenance requirements.
Solution Approach 2:
The patent extracts and removes the brush component from the electric starter system. By eliminating the brushes that cause wear, the system achieves longer operational life without requiring the complex brush assembly structure.
2Force
If a brushed motor is used, then the device complexity is lower, but the torque output is substantially zero near the upper bound of speed range
Solution Approach 1:
The patent substitutes the brushed motor with a brushless electric machine that uses permanent magnets and electronic commutation. This design maintains high torque output across the entire speed range, including near the upper bound, by eliminating the mechanical limitations of brush contacts.
Solution Approach 2:
The patent changes the operational parameters of the electric machine by using electronic control to vary current phases and timing. This allows the brushless motor to maintain optimal torque production across a wider speed range compared to brushed motors.
3Productivity
If sequential solenoid actuation is used, then the device complexity is lower, but there are time delays and voltage drops affecting restart efficiency
Solution Approach 1:
The patent replaces the sequential mechanical solenoid actuation system with an electronic control system using pulse width modulation (PWM). This eliminates mechanical delays and voltage drops by using electronic switching, significantly improving engine restart efficiency and responsiveness.
Solution Approach 2:
The patent uses pulse width modulation with periodic switching of power electronics to control the electric machine. This periodic electronic action replaces the sequential mechanical solenoid operation, eliminating time delays and reducing voltage drops while maintaining precise control.
4Force
If conventional brushed starters are used, then the manufacturing cost is lower, but the torque consistency over speed range is poor
Solution Approach 1:
The patent employs electronic control parameters including PWM duty cycle variation and phase angle adjustment to maintain consistent torque output across the speed range. The brushless electric machine's permanent magnet design combined with electronic commutation allows precise torque control that brushed motors cannot achieve.
Solution Approach 2:
The substitution of the brush contact mechanism with electromagnetic fields and electronic control enables superior torque consistency. The brushless design eliminates the mechanical wear and contact resistance variations that cause torque fluctuations in brushed motors.
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
The brushless electric starter system provides consistent torque over a wider speed range, reduces engine restart time, and mitigates voltage drops, enhancing propulsion system responsiveness and efficiency.
Implementation Method 1
The controller is also programmed to operate a plurality of switches in connection with the power supply using pulse width modulation (PWM) to generate the multi-phase alternating current
Implementation Method 2
The starter module includes a brushless electric machine to generate an output torque to crank start the engine
Implementation Method 3
The rotor includes a plurality of permanent magnets that are driven to rotate in response to power supplied to the plurality of windings of the stator
Data Source
AI summary
A vehicle propulsion system includes an engine configured to be selectively activated to provide torque to propel the vehicle and a starter module coupled to the engine and configured to start the engine from an inactive state. The starter module includes a brushless electric machine to generate an output torque to crank start the engine. The starter motor also includes a pinion gear coupled to the electric machine, where the pinion gear is actuatable to selectively engage a cranking input of the engine. A controller assembly is programmed to cause actuation of the pinion gear to engage the cranking input of the engine and transfer a cranking torque to activate the engine.