Arc-Shaped Inverter Busbar Layout for Compact Electric Drives
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Solution Overview
Problem
Existing onboard electric drive units for vehicles face challenges due to the large size and weight of inverters, which generate heat and noise, and require significant cooling, leading to inefficiencies and limitations in vehicle design.
Innovation Solution
The electric drive unit incorporates a thin case with a thickness of less than 50 mm, featuring a unique arrangement and shape of power modules, a smoothing capacitor, and busbars, which reduces the size and weight while improving heat dissipation and controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the busbar has a long wiring length to connect power modules to smoothing capacitor, then the inverter can accommodate all components, but electric resistance increases and copper loss is generated
Solution Approach 1:
The busbar is configured to extend in the circumferential direction rather than radially, changing the spatial dimension of current flow. This circumferential arrangement shortens the effective current path length while maintaining proper electrical connections, thereby reducing copper loss without compromising inverter compactness
2Ease of operation
If the busbar has a complex shape to connect components, then all connections can be made, but noise, vibration, and electromagnetic interference increase
Solution Approach 1:
The busbar features an arc-shaped inner edge portion that smoothly connects to the smoothing capacitor terminal. This curved geometry eliminates sharp corners and abrupt directional changes in the current path, reducing electromagnetic radiation and interference while maintaining effective electrical connectivity between components
3Temperature
If the inverter is made large to accommodate components with adequate spacing, then heat dissipation can be improved, but the inverter becomes heavy and difficult to dispose in vehicle
Solution Approach 1:
The inverter is integrated with the motor by disposing it adjacent to the motor in the rotational axis direction, merging two previously separate components into a compact assembly. This integration reduces overall weight and eliminates the need for separate mounting spaces, while the thin case design maintains adequate thermal management through optimized component arrangement
4Volume of moving object
If the inverter case is made thin to reduce size, then vehicle design flexibility improves, but accommodating all electronic components becomes difficult
Solution Approach 1:
Power modules are arranged in the circumferential direction around the smoothing capacitor, utilizing the radial-circumferential space within the thin case. This two-dimensional circumferential arrangement allows all components to be accommodated in a compact thickness while maintaining proper spacing and connectivity
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 achieves size and weight reductions, enhances performance by improving heat dissipation and reducing noise, and increases flexibility in vehicle design, leading to better fuel and electricity consumption.
Implementation Method 1
When the wiring length (corresponding to a distance over which current flows) of the busbar increases, electric resistance increases accordingly, and a copper loss is generated during energization
Implementation Method 2
since large current is turned on and off at a high speed by switching control in the inverter, a large change in magnetic field is generated in the busbar accordingly
Implementation Method 3
a plurality of power modules each of which includes at least one switching element, the plurality of power modules constituting an inverter circuit configured to convert direct-current power into alternating-current power
Data Source
AI summary
An inverter is disposed adjacent to one end of a motor in a rotational axis direction. The inverter includes a plurality of power modules each including a switching element, a smoothing capacitor, busbars that connect the power modules to the smoothing capacitor, and a thin case that accommodates these components. The plurality of power modules are disposed at the periphery of the smoothing capacitor and arranged in the circumferential direction. The busbars are formed to extend in the circumferential direction. An inner edge portion of each of the busbars connected to a terminal of the smoothing capacitor has an arc shape or a circular shape.