Crossover Bus Bar Inductance Reduction in Locomotive Inverters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional inverter drive systems for large traction motors in locomotives experience increased inductance and undesirable circulating currents due to solid bus connections between inverters, leading to height issues and inefficiencies, particularly when trying to meet locomotive clearance requirements.
Innovation Solution
The implementation of a crossover bus bar with a combination of laminated and solid bus connections, where laminated bus sections are connected by solid bus bars, reducing inductance and circulating currents while allowing for a more compact design by locating the crossover bus bar at the bottom of the inverter assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid bus bar is used to connect inverters on opposed sides of the plenum, then electrical connection is achieved, but inductance increases and circulating currents increase
Solution Approach 1:
The bus bar connection is segmented into multiple laminated sections rather than using a single solid bus bar. Each inverter is connected to its own laminated bus section, which are then interconnected through the plenum. This segmentation reduces the effective inductance by breaking up the current path into smaller, more controlled segments with reduced magnetic coupling.
Solution Approach 2:
The plenum space between inverters on opposed sides is utilized as an intermediary pathway for electrical connection. Instead of spanning the plenum with a long solid bus bar, laminated bus sections extend from each inverter into the plenum and are interconnected there, using the plenum as a mediator that reduces inductance while maintaining electrical connectivity.
2Reliability
If a solid bus bar spans the plenum to connect opposed inverter arrays, then electrical connection is provided, but the height of the inverter assembly increases
Solution Approach 1:
The electrical connection approach transitions from a vertical dimension (spanning the plenum height with a long bus bar) to a horizontal/distributed dimension (laminated bus sections extending laterally from each inverter and interconnecting within the plenum plane). This dimensional change reduces the vertical height requirement while maintaining electrical connectivity.
Solution Approach 2:
The single long vertical bus bar connection is segmented into multiple shorter laminated sections distributed horizontally from each inverter. This segmentation eliminates the need for a tall vertical span, reducing the overall assembly height while providing the necessary electrical interconnection through distributed lateral connections.
3Temperature
If inverters are spaced apart by five feet to allow ventilation air circulation, then cooling is achieved, but inductance between inverters increases
Solution Approach 1:
The plenum space, which must exist for ventilation purposes, is repurposed as an intermediary electrical connection medium. Laminated bus sections extend into this plenum space and are interconnected, transforming the harmful inductive effect of the spaced-apart configuration into a beneficial low-inductance connection pathway that utilizes the existing spatial separation for both cooling and electrical connection.
Solution Approach 2:
The connection geometry parameters are changed from a single long-distance span to multiple short-distance laminated sections. By changing the physical configuration from one long bus bar to many short laminated segments distributed through the plenum, the inductance parameter is reduced while maintaining the five-foot spacing required for ventilation.
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 inductance and circulating currents, improves current distribution, and allows for a lower profile inverter drive assembly, enhancing electrical performance and meeting mechanical packaging constraints, thereby increasing ground clearance and reducing weight and cost.
Implementation Method 1
reducing inductance and circulating currents
Implementation Method 2
a solid bus connection interconnecting the first laminated bus section with the second laminated bus section
Data Source
AI summary
An inverter drive assembly includes a first array of inverters, a second array of inverters spaced from the first array of inverters and defining a plenum therebetween, and a crossover bus bar spanning the plenum and electrically connecting the first array of inverters to the second array of inverters. The crossover bus bar includes a first laminated bus section electrically connected to the first array of inverters, a second laminated bus section electrically connected to the second array of inverters, and a solid bus connection interconnecting the first laminated bus section with the second laminated bus section.