Distributed Inverter Layout for Low-Voltage High-Current Drives
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Solution Overview
Problem
Low-voltage multipole motors face challenges with high current requirements leading to cable losses and the need for complex wiring, particularly for neutral point connections, which complicates the design and increases costs.
Innovation Solution
The electric drive incorporates first and second inverters at opposite axial ends of the stator, eliminating the need for neutral point wiring by connecting DC links across the stator, using half- or full-bridge setups with controllable semiconductor switches and capacitors to supply field conductors, and employing stacked inverters to manage high current demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If low-voltage supply is used for multipole motors, then motor size can be reduced, but cable losses increase and transformer current rating requirements increase
Solution Approach 1:
The motor windings are segmented into multiple pole groups, with each group connected to a separate inverter module. This segmentation allows the use of lower voltage per inverter while distributing the total power across multiple channels, reducing the current burden on individual cables and transformers.
Solution Approach 2:
The patent transitions from a single centralized power conversion system to a distributed multi-module architecture. By adding the dimension of spatial distribution across multiple inverter modules, the system achieves lower voltage operation without proportionally increasing cable losses, as each module handles a fraction of the total current.
2Power
If high current is required for low-voltage operation, then motor power can be maintained, but wiring complexity and neutral point connections increase
Solution Approach 1:
The power conversion system is divided into multiple independent inverter modules, each handling a subset of pole groups. This segmentation eliminates the need for complex neutral point wiring by providing separate return paths for each module, significantly reducing wiring complexity while maintaining the required motor power.
Solution Approach 2:
The patent resolves the wiring complexity issue by moving from a single-phase reference system to a multi-phase distributed system. Each inverter module operates independently with its own DC link, creating additional dimensional separation that eliminates the need for neutral point connections and reduces overall wiring complexity.
3Stress or pressure
If multiple pole groups are connected in series across DC link, then high voltage operation is achieved, but amount of wiring particularly for neutral points increases
Solution Approach 1:
Instead of connecting multiple pole groups in series to achieve high voltage (which increases wiring), the patent inverts the approach by using multiple parallel inverter modules, each operating at lower voltage. This inversion eliminates the need for neutral point wiring while maintaining the ability to drive high-power motors through distributed power delivery.
Solution Approach 2:
The patent segments the power conversion system into multiple independent inverter modules, each with its own DC link and control circuitry. This segmentation allows high voltage operation to be achieved through series connection of multiple module outputs rather than series connection of pole groups, thereby reducing wiring complexity and eliminating neutral point connections.
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 configuration reduces wiring complexity and parasitic effects, lowers current requirements, and simplifies power conversion, while maintaining efficient operation and reducing costs, especially for high-power motors.
Implementation Method 1
The stator comprises a plurality of field conductors for generating a magnetic field for conveying a torque to the rotor
Data Source
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AI summary
An electric drive, particularly a low-voltage, high current electric drive featuring bars as field conductors has first inverters arranged at a first axial end of the stator and second inverters arranged at a second axial end of the stator, the second axial end being opposite the first axial end.