Field Winding Synchronous Machine Interpole Gap Design
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Solution Overview
Problem
Field winding type synchronous machines face issues with large torque ripples and insufficient torque generation at maximum load due to magnetic flux saturation in interpole portions, and existing excitation methods are inefficient at low rotational speeds or when rotation is stopped.
Innovation Solution
The design includes a rotor with main and interpole portions, where the interpole windings produce induced current by a magnetic flux generated by time harmonic currents superimposed on the fundamental wave of the stator coil, with larger electromagnetic gaps between interpole portions and the stator to prevent saturation, and a rectifier circuit to energize the main pole windings, allowing for increased torque production at maximum load and effective excitation across a wide range of rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interpole portions are used to reduce torque ripple, then torque ripple is reduced, but interpole portions become saturated at maximum load resulting in insufficient torque generation
Solution Approach 1:
The patent changes the electromagnetic gap parameter specifically for interpole portions, making it larger than the gap for main pole portions. This parameter change prevents magnetic flux saturation in interpole portions at maximum load, allowing both torque ripple reduction and sufficient torque generation to be achieved simultaneously
2Device complexity
If conventional excitation methods are used, then the system is simple, but sufficient excitation cannot be maintained at low rotational speeds or when stopped
Solution Approach 1:
The patent introduces a rectifier circuit as an intermediary component that converts induced current from interpole windings into field current for main pole windings. This intermediary mechanism enables effective excitation at low rotational speeds by rectifying the induced current, while maintaining system functionality across the full speed range
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 enables the production of larger torque at maximum load and maintains effective excitation even at low rotational speeds or when stopped, making it suitable for hybrid or electric vehicles with varying rotational speeds.
Implementation Method 1
The interpole windings produce the induced current by a magnetic flux generated by a time harmonic current superimposed on a fundamental wave of the stator coil
Implementation Method 2
a rectifier circuit that rectifies the induced current to a field current and energizes the field current to the main pole windings
Implementation Method 3
main pole portions making a field magnetic flux flow to the stator core
Data Source
AI summary
A field winding type synchronous machine has a stator having a stator core to which a stator coil is wound, and a rotor that rotates while facing a peripheral surface of the stator with an electromagnetic gap therebetween. The rotor includes a rotor core having a plurality of main pole portions and interpole portions, main pole windings wound around the main pole portions, interpole windings wound around the interpole portions, and a full-wave rectifier circuit for energizing the field current to the main pole windings. The interpole windings produce the induced current by a magnetic flux generated by a time harmonic current superimposed on a fundamental wave of the stator coil. The electromagnetic gaps between the interpole portions and a circumferential surface of the stator are configured larger than electromagnetic between the main pole portions and the circumferential surface of the stator.