Alternator Field Winding Control for FEAD Speed
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Solution Overview
Problem
Conventional vehicle alternators face inefficiencies in meeting increased electrical loads, particularly in autonomous vehicles, due to varying engine speeds and inefficient operation of front end accessory devices (FEAD), leading to insufficient electrical output and increased vehicle mass when alternator size is increased.
Innovation Solution
An electric machine with multiple armature and field windings, where the controller adjusts current supplied to the second field winding to control FEAD speed, ensuring efficient operation and balanced power distribution between alternators, thereby optimizing vehicle driveline efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the alternator size is increased to provide sufficient electrical output for increased loads, then the electrical power capacity is improved, but the vehicle mass increases, thereby decreasing fuel efficiency
Solution Approach 1:
The patent applies dynamics by making the alternator's mechanical load variable through electronic control of field current. The alternator can dynamically adjust its torque demand on the engine based on electrical load requirements, allowing a smaller alternator to provide sufficient electrical output when needed without continuously dragging down engine efficiency. This resolves the contradiction by enabling high power capacity on demand while maintaining low mass and good fuel efficiency during normal operation.
Solution Approach 2:
The patent changes the parameter of field current to control the alternator's operational characteristics. By adjusting field current, the system can vary the alternator's electrical output capacity and mechanical torque demand independently of its physical size. This allows the same alternator to operate at different power levels, providing high electrical output when needed while maintaining lower mass and better fuel efficiency during normal operation.
2Adaptability or versatility
If the engine speed varies to meet driving conditions, then the adaptability to different driving scenarios is improved, but the alternator operates at speeds where it is less efficient, and FEAD devices operate inefficiently
Solution Approach 1:
The patent applies dynamics by enabling the alternator to dynamically adjust its field current and torque demand in response to varying engine speeds. Rather than requiring fixed-speed operation for efficiency, the system can adapt to different engine speeds by modulating electrical and mechanical output, allowing the engine to operate in its optimal speed range while the alternator compensates to maintain efficient operation of both electrical output and FEAD devices.
Solution Approach 2:
The patent implements feedback control where the controller monitors engine speed, electrical load requirements, and FEAD operational status to continuously adjust field current. This feedback mechanism ensures that the alternator operates efficiently across varying engine speeds by making real-time adjustments to balance electrical power generation with mechanical torque demand on the engine, preventing energy losses from mismatched operating conditions.
3Adaptability or versatility
If a clutch is installed between FEAD accessories and the engine to enable variable speed operation, then the speed control capability is improved, but the driveline efficiency decreases
Solution Approach 1:
The patent replaces the mechanical clutch system with an electronic control system that regulates FEAD speed by controlling the alternator's field current. Instead of using a mechanical disconnect device that would introduce losses and complexity, the system uses electromagnetic control to achieve variable speed operation of FEAD devices. This substitution maintains driveline efficiency while providing the necessary speed control capability for optimal FEAD operation across different driving conditions.
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 improves FEAD device speed control, enhances driveline efficiency, and tailors mechanical and electrical outputs to meet the demands of autonomous vehicles without increasing vehicle mass or decreasing fuel efficiency.
Implementation Method 1
a second field winding, the first field winding and the first armature winding at least partially wrapped by the second field winding
Data Source
AI summary
Control of alternator/starters for providing electrical power to a vehicle and rotating an engine is disclosed. In one example, the alternator/starter provides a differential action whereby torque on an input side of the alternator may be maintained while speed of an output side of the alternator may be varied. The alternator/starter includes two armature windings and two field windings.