Modular Multilevel Converter Ring Topology for Multi-Phase Motor Control
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Solution Overview
Problem
Conventional batteries and electric drive systems face challenges in providing AC voltage with low amplitude and high frequency, leading to high losses and distortions, especially in electric vehicles, where a higher number of phases would improve torque control but increases complexity, and existing inverters struggle to produce multiple phases efficiently.
Innovation Solution
A modular multilevel converter system with a multiplicity of windings and individual modules connected in a ring configuration, allowing for the creation of additional phase terminals and voltage differences, enabling finer control of the rotating field and increased failsafety by dynamically reconfiguring energy storage and switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional inverters are used to produce AC voltage, then the system can operate with a standard three-phase configuration, but the system suffers from high losses and high voltage distortions when the required voltage amplitude is much lower than the maximum amplitude
Solution Approach 1:
The battery pack is divided into multiple individual modules (first battery module, second battery module, etc.), each with its own voltage output. These modules are connected in parallel to form a composite battery pack that can independently control voltage amplitude for each phase, enabling low amplitude AC voltage output without high losses.
2Reliability
If the number of phases in the electric motor is increased to improve torque control and reduce differential voltages, then the motor performance is improved, but the system complexity increases
Solution Approach 1:
The battery pack is segmented into multiple independent modules corresponding to different phases. Each module can be independently controlled to provide the required phase voltage, enabling complex multi-phase motor control while maintaining a relatively simple overall system architecture through modular design.
Solution Approach 2:
The composite battery pack structure allows the same modular architecture to support different phase configurations (three-phase, five-phase, etc.) and different voltage requirements, making the system universally applicable to various motor types and control strategies without requiring complete system redesign.
3Device complexity
If conventional hardwired battery units are used, then the battery structure is simple, but the system lacks failsafety and cannot continue operation if one battery part fails
Solution Approach 1:
The battery pack is divided into multiple independent modules connected in parallel. If one module fails, the other modules can continue to supply power independently, providing inherent failsafety without requiring complex backup systems. The modular structure allows graceful degradation of performance rather than complete system failure.
Solution Approach 2:
Each battery module has its own characteristics and can be independently managed. The system allows different modules to have different states of charge or performance characteristics while maintaining overall system functionality. This local independence enables targeted replacement or maintenance of individual modules without affecting the entire battery pack.
Data Source
AI summary
An electric machine has a multiplicity of windings having a first terminal and a second terminal. At least one node exists to which one of the two terminals of a respective winding from the multiplicity of windings is electrically connected. The corresponding other terminal of a respective winding from the multiplicity of windings is electrically connected to a phase terminal, and to a modular multilevel converter that has a multiplicity of individual modules that are connected up in series to form a ring. At least one tap can be arranged between two respective adjacent individual modules and provides a phase terminal to which the first or the second terminal of a winding from the multiplicity of windings of the electric machine is electrically connected. A number of taps of the modular multilevel converter corresponds exactly to a number of windings from the multiplicity of windings of the electric machine.