Inductance Augmenter for Electric Machine Stator Extension
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designers of permanent magnet alternators face challenges in optimizing inductance and machine performance, particularly when the machine is used as both a generator and a motor, due to conflicting requirements for the number of control winding turns and inductance, which can lead to voltage loss and heating issues, and the need for additional regulation systems that increase weight and complexity.
Innovation Solution
The electric machine incorporates a stator extension made of magnetic material coaxial with the stator, with control windings wrapped around it, extending beyond the rotor, creating a magnetic circuit that remains unsaturated to increase the inductance of the control windings, maintaining minimum inductance even at high saturation levels, and utilizing multiple magnetic circuits to enhance inductance regardless of saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of control winding turns is increased to increase inductance, then current ripple is minimized and inductance is increased, but voltage loss and heating increase
Solution Approach 1:
The invention extends the control winding axially beyond the rotor terminus into an extended stator region, adding a spatial dimension to the magnetic circuit. This axial extension creates additional magnetic path length that increases inductance without requiring additional turns in the radial direction, thereby avoiding the voltage loss and heating associated with increased turn count.
Solution Approach 2:
The invention changes the magnetic circuit parameters by extending the stator axially and providing a dedicated magnetic path in the extended region. This parameter change allows the same control winding to achieve higher inductance through geometric modification rather than increasing current, thus reducing I²R losses and voltage drop.
2Reliability
If a shunt regulation system is added to control voltage in low- or no-load conditions, then voltage regulation is achieved, but weight and complexity increase
Solution Approach 1:
The extended stator with control windings serves multiple functions: it provides voltage regulation in low- or no-load conditions, controls output voltage and frequency, and maintains inductance across operating conditions. This multi-functionality eliminates the need for separate shunt regulation systems, reducing overall system complexity and weight.
Solution Approach 2:
The control winding system in the extended stator is self-regulating through its inductance characteristics. By controlling current through the control winding, the system automatically regulates voltage without requiring external regulation apparatus, making the machine self-sufficient for voltage control.
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 increases the inductance of the control windings, maintaining minimum inductance at high saturation levels, reducing voltage loss and heating, and allowing for efficient control of output voltage and current without the need for additional regulation systems, thus improving machine performance and reducing weight and complexity.
Implementation Method 1
the stator extension configured such that in use the magnetic circuit remains unsaturated thereby increasing inductance of at least one control winding
Implementation Method 2
a stator extension of a magnetic material, the stator extension disposed coaxially with the stator, the stator extension having only the at least one control winding wrapped therearound
Data Source
AI summary
The electric machine comprises a rotor and stator, the rotor and stator having generally equal axial lengths. The stator has at least one primary and at least one control winding disposed around the stator. The electric machine comprises a stator extension of a magnetic material. The stator extension is disposed coaxially with the stator and has only the at least one control winding wrapped therearound. The stator extension extends axially adjacent the stator beyond an axial terminus of the rotor and defines a magnetic circuit around the at least one control winding. The stator extension is configured such that in use, the magnetic circuit remains unsaturated thereby increasing inductance of at least one control winding in an electric alternator/motor.