Six-Phase Stator Winding to Suppress MMF Harmonics
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Solution Overview
Problem
Existing AC induction motors face challenges with high rotor losses due to stator MMF harmonics, particularly the 5th and 7th harmonics, leading to increased rotor temperature and demagnetization risk, especially in high-speed applications, while permanent magnet synchronous motors (PMSMs) suffer from low field weakening capability and high rotor current.
Innovation Solution
A six-phase winding scheme is introduced for AC motors, comprising two separate sets of three-phase connections with a 30-degree phase shift, reducing higher order harmonics and maintaining fundamental harmonics, thereby improving reliability and performance without altering the motor's geometry or size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional three-phase winding connection is used, then the motor structure is simple, but higher order harmonics (5th and 7th) cause high rotor losses and increased rotor temperature
Solution Approach 1:
The three-phase winding connection is segmented into two separate sets of three-phase connections (first and second sets), each with its own power supply. This segmentation allows independent control of harmonic components, enabling suppression of 5th and 7th harmonics while maintaining fundamental harmonics for torque production, thereby reducing rotor losses without excessive complexity increase
Solution Approach 2:
The invention changes the electrical parameters by introducing a 30-degree phase shift between the two sets of three-phase connections. This parameter change fundamentally alters the harmonic spectrum, causing 5th and 7th harmonics to cancel out while preserving fundamental harmonics, thus reducing rotor losses through parameter optimization rather than structural complexity
2Power
If permanent magnet synchronous motors are used, then high torque is achieved, but field weakening capability is low and rotor current is high
Solution Approach 1:
The invention implements dynamic control by allowing independent adjustment of the two sets of three-phase power supplies. This dynamic capability enables real-time optimization of field weakening during high-speed operation while maintaining high torque at lower speeds, making the motor adaptable to varying operational requirements without being constrained by fixed characteristics
3Reliability
If six-phase winding configuration is implemented, then higher order harmonics are suppressed and rotor losses are reduced, but the winding connection becomes more complex
Solution Approach 1:
The invention extracts and eliminates harmful 5th and 7th harmonics from the motor operation through the six-phase winding configuration, separating them from the useful fundamental harmonics. This extraction approach improves reliability by removing harmful components while preserving beneficial ones, achieving net reliability improvement despite increased connection complexity
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 six-phase winding configuration significantly reduces rotor losses and maintains torque at high speeds, enhancing motor performance and reliability by suppressing higher order harmonics without increasing weight or size, and ensuring efficient operation.
Implementation Method 1
the motor that converts the alternating current into mechanical power by using an electromagnetic induction phenomenon is called an Alternating Current (AC) motor
Data Source
AI summary
A six phase stator winding of a motor that has reduced MMF harmonics characteristics is provided. The stator winding has two sets: a first set and a second set of three phase winding connection. The first set and the second set of the three phase winding connection are connected parallel to each other, such that the two sets of the three-phases are shifted by 30-degree electrical angle with respect to each other, where the second set of is leading.