Multi-Harmonic FOC for Poly-Phase Torque and Rotor Loss Control
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Solution Overview
Problem
Traditional poly-phase motor and generator systems face inefficiencies due to excessive power losses in rotor windings from harmonic currents, which are typically avoided in three-phase designs, limiting their torque output and overall performance.
Innovation Solution
Implementing a multi-harmonic field-oriented control (FOC) method that integrates harmonic injection techniques with FOC in poly-phase systems, allowing for coordinated control of torque and magnetizing components across active harmonic planes to enhance energy transfer and torque generation at multiple frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If harmonic injection techniques are used to improve voltage capability, then voltage capability is improved, but power losses in rotor windings increase
Solution Approach 1:
The patent segments the control of different harmonic planes independently, allowing each harmonic component to be controlled separately. This enables selective injection of harmonics that improve voltage capability while minimizing those that cause excessive rotor losses, thus resolving the contradiction between voltage capability and power losses.
Solution Approach 2:
The patent changes the control parameters by extending field-oriented control to multiple harmonic planes, allowing dynamic adjustment of harmonic current magnitudes and phases. This enables optimization of voltage capability while controlling rotor losses through parameter tuning of each harmonic component.
2Power
If harmonic currents are injected to enhance torque output, then torque density is improved, but power losses in rotor windings increase
Solution Approach 1:
The patent segments torque production across multiple harmonic planes, allowing torque to be generated at different frequencies independently. This enables optimization of torque density by selecting harmonics that produce useful torque while minimizing those that cause excessive rotor losses.
Solution Approach 2:
The patent converts the typically harmful harmonic currents that cause rotor losses into beneficial torque-producing components by carefully selecting and controlling specific harmonic planes. Harmonics that would normally be suppressed are instead utilized to generate additional torque while maintaining acceptable loss levels.
3Device complexity
If traditional FOC based on fundamental frequency is used, then control simplicity is maintained, but performance in poly-phase machines is limited
Solution Approach 1:
The patent extends the universal field-oriented control framework to multiple harmonic planes, allowing the same control methodology to be applied across different frequency components. This maintains the simplicity and systematic approach of traditional FOC while enhancing performance through multi-frequency operation.
Solution Approach 2:
The patent adds the frequency dimension to traditional FOC by controlling multiple harmonic planes simultaneously. This transforms the control from a single-frequency approach to a multi-frequency approach, enhancing performance while maintaining the structured control methodology through systematic extension to additional dimensions.
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 approach improves the efficiency and power density of poly-phase motor/generator systems by effectively managing harmonic currents, reducing losses, and optimizing torque output across multiple harmonic planes.
Implementation Method 1
a plurality of power converters connected to respective windings, wherein the plurality of power converters is configured to control currents of the plurality of windings
Data Source
AI summary
A method includes configuring a motor drive system with a motor/generator and a plurality of inverters coupled to the motor/generator, configuring a plurality of active harmonic planes to generate a torque on each of the active harmonic planes, and applying a harmonic plane synchronization mechanism to the plurality of active harmonic planes so that torque components and magnetizing components of currents are controlled in coordination on different active harmonic planes to output a desired torque from the motor/generator.