Rotating Electric Machine Torque Ripple Control
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Solution Overview
Problem
Existing rotating electric machine configurations face challenges in achieving required performance at both low-speed and high-speed ranges with high torque efficiency, as they either incur high costs or require complex switching of stator winding characteristics, and the half-wave driving process results in increased torque ripple.
Innovation Solution
A rotating electric machine apparatus with a double-layer winding configuration, utilizing a full-bridge inverter and neutral point switches, performs full-wave and half-wave driving processes to manage torque ripple, where the half-wave process is optimized by shifting energization control timings and using neutral point switches to opposite current flow directions in the coils, reducing torque ripple and increasing average torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a half-wave driving process is performed at high-speed range, then the rotating electric machine can operate in high-speed range, but torque ripple increases
Solution Approach 1:
The stator winding is segmented into two independent sets (first stator winding and second stator winding), each connected in different configurations (delta and star respectively). This segmentation allows selective activation of appropriate windings based on operating conditions, enabling half-wave driving at high speeds while maintaining torque quality through proper winding selection and combination.
Solution Approach 2:
The system dynamically switches between different winding configurations and driving modes (full-wave vs. half-wave) based on rotation speed requirements. The control device selects appropriate stator windings and switching patterns in real-time, allowing the machine to adapt to varying speed conditions while minimizing torque ripple through optimized control strategies.
2Adaptability or versatility
If DCDC converter is provided to vary voltage for wide rotation-speed range, then required performance at low-speed and high-speed ranges can be obtained, but the configuration becomes costly
Solution Approach 1:
Different portions of the stator winding are designed with different characteristics (delta-connected first winding for high-speed, star-connected second winding for low-speed). This local differentiation in winding quality allows the same machine to deliver optimal performance across wide speed ranges without requiring external voltage conversion equipment like DCDC converters.
Solution Approach 2:
The rotating electric machine achieves multi-functionality by incorporating both delta-connected and star-connected stator windings within a single machine structure. This universal design enables the machine to operate efficiently across both low-speed and high-speed ranges, replacing the need for separate machines or additional power conversion equipment.
3Adaptability or versatility
If stator winding characteristics are switched during operation, then required performance at different speed ranges can be obtained, but the configuration becomes complex and operation must be temporarily stopped during switching
Solution Approach 1:
Both delta-connected and star-connected stator windings are pre-configured within the machine structure before operation begins. This preliminary preparation of multiple winding configurations eliminates the need for complex real-time switching operations, allowing seamless transitions between operating modes without stopping the machine or introducing operational interruptions.
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 solution effectively reduces torque ripple and increases average torque in the rotating electric machine during the half-wave driving process, enhancing performance across speed ranges while maintaining a simple configuration and reducing heat generation.
Implementation Method 1
a full-bridge inverter that performs electric power transfer with the rotating electric machine
Implementation Method 2
a first coil of each of N phases that is wound around a stator core and is connected by a star connection; and a second coil of each of N phases that is wound around the stator core while being electrically insulated from the first coil
Data Source
AI summary
A rotating electric machine apparatus includes a rotating electric machine and a full-bridge inverter. The full-bridge inverter includes first high-side switches, first low-side switches, second high-side switches, and second low-side switches. The rotating electric machine apparatus includes: first and second neutral point switches; a full-wave driving unit that performs a full-wave driving process in which switching control of the switches is performed in a state in which the first and second neutral point switches are turned off; a half-wave driving unit that performs a half-wave driving process in which switching control of the first high-side switches and the second low-side switches is performed in a state in which the first and second neutral point switches are turned on, and the first low-side switches and the second high-side switches are turned off; and an executing unit that selects and performs either of the full-wave driving process and the half-wave driving process.