Field Winding Synchronous Machine Drive Torque Ripple Reduction
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Solution Overview
Problem
Field winding synchronous machines experience torque ripple due to harmonic components in the stator magnetic field, which are not effectively mitigated by existing technologies.
Innovation Solution
A field winding synchronous machine drive system that includes a stator and rotor with specific configurations for stator coils and inverters, where time-harmonic currents are superimposed on fundamental-wave currents and phase-shifted to cancel each other out, reducing torque ripple. The system uses multiple inverters to supply m-phase alternating currents to stator coils, with phase differences set to minimize torque ripple, and includes a bridge circuit and capacitor to manage excitation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If time-harmonic currents are superimposed on fundamental-wave currents to generate torque, then torque generation is improved, but torque ripple increases due to harmonic components
Solution Approach 1:
The patent applies the principle of converting harm into benefit by utilizing time-harmonic currents, which initially cause torque ripple as a harmful effect, but by superimposing multiple sets of time-harmonic currents with different phase relationships, the harmful torque ripple components are transformed into beneficial torque generation. The harmonic components that would normally cause vibration and torque fluctuation are instead harnessed to produce additional torque, thereby converting the harmful effect into a useful one for improving overall torque generation capability.
Solution Approach 2:
The patent employs parameter changes by modifying the phase relationships and frequency characteristics of multiple time-harmonic currents. By adjusting the phase differences between different sets of time-harmonic currents and controlling their superposition, the system optimizes the torque generation while minimizing torque ripple. This involves changing the temporal and phase parameters of the current waveforms to achieve desirable torque characteristics.
2Object-generated harmful factors
If multiple inverters supply m-phase alternating currents with phase differences to cancel time-harmonic currents, then torque ripple is reduced, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the current supply system into multiple independent inverter units, each responsible for supplying m-phase alternating currents to specific stator coils. This segmentation allows each inverter to be controlled independently to generate time-harmonic currents with specific phase relationships, enabling the cancellation of torque ripple components while maintaining modular system architecture that manages complexity through division of functions.
Solution Approach 2:
The patent implements universality by designing the inverter system to perform multiple functions: generating fundamental-wave currents for primary torque generation, superimposing time-harmonic currents for torque ripple cancellation, and coordinating phase relationships across multiple inverters. This multi-functionality allows the same inverter architecture to handle both torque generation and torque ripple mitigation without requiring separate dedicated systems.
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 system effectively reduces torque ripple by canceling time-harmonic currents and managing excitation currents, leading to improved torque consistency and reduced magnetic saturation in the rotor.
Implementation Method 1
The stator includes N m-phase stator coils wound on the stator core to create a rotating magnetic field
Implementation Method 2
The rotor includes at least one main field winding wound on the rotor core to create field magnetic flux
Implementation Method 3
each of the inverters supplies the corresponding m-phase stator coil with the m-phase alternating current which includes a fundamental-wave current and a time-harmonic current superimposed on the fundamental-wave current; the time-harmonic current has a shorter period than the fundamental-wave current
Data Source
AI summary
A field winding synchronous machine drive system includes a field winding synchronous machine having a stator and a rotor and a drive apparatus configured to drive the field winding synchronous machine. The stator has N m-phase stator coils wound on a stator core to create a rotating magnetic field, where N is an integer not less than 2 and m is an integer not less than 3. The rotor has at least one main field winding wound on a rotor core to create field magnetic flux. The drive apparatus includes N inverters each of which supplies m-phase alternating current to a corresponding one of the N m-phase stator coils. Specifically, each of the inverters supplies the corresponding m-phase stator coil with the m-phase alternating current which includes a fundamental-wave current and a time-harmonic current superimposed on the fundamental-wave current; the time-harmonic current has a shorter period than the fundamental-wave current.