Four-Layer Bus Bar Structure for DC Inductance Reduction
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Solution Overview
Problem
The conventional power conversion device's three-layer bus bar structure with an intermediate connection bus bar between positive-electrode-side and negative-electrode-side bus bars results in insufficient reduction of DC wiring inductances, leading to spike voltage issues in semiconductor switching elements.
Innovation Solution
A power conversion device with a 4-layer bus bar structure where two positive-electrode-side bus bars are connected in parallel and one negative-electrode-side bus bar, along with an intermediate connection bus bar, are stacked in close contact with insulating layers, forming non-adjacent connection lines to cancel out DC wiring inductances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an intermediate connection bus bar is interposed between the positive-electrode-side bus bar and the negative-electrode-side bus bar to form a three-layer structure, then the current flows of adjacent bus bars can be made opposite to each other, but the distance between the positive-electrode-side bus bar and the negative-electrode-side bus bar becomes large, resulting in insufficient inductance reduction
Solution Approach 1:
The positive-electrode-side connection is segmented into two separate bus bars (first and second positive-electrode-side bus bars) that are positioned adjacent to the negative-electrode-side bus bar. This segmentation allows the current paths to be optimized for inductance reduction while maintaining compact spacing between opposing current flows.
Solution Approach 2:
The patent transitions from a conventional three-layer stacked structure to a four-layer structure by adding another dimension of bus bar arrangement. The first and second positive-electrode-side bus bars are arranged in parallel adjacent to the negative-electrode-side bus bar, creating a multi-dimensional current path configuration that reduces inductance more effectively than the traditional three-layer approach.
2Object-generated harmful factors
If a three-layer bus bar structure is used with an intermediate connection bus bar, then the structure is simpler to manufacture with identical bus bar shapes, but the inductance reducing effect is not sufficiently obtained
Solution Approach 1:
The positive-electrode-side connection is divided into two separate bus bars arranged in parallel, creating a four-layer structure. This segmentation enables better current path optimization for inductance reduction while maintaining manufacturing simplicity through standardized bus bar designs.
Solution Approach 2:
The first and second positive-electrode-side bus bars are connected in parallel to form the positive-electrode-side connection, combining multiple current paths to achieve lower inductance. This merging of parallel paths provides the inductance reducing effect while maintaining structural regularity.
3Object-affected harmful factors
If the distance between positive-electrode-side bus bar and negative-electrode-side bus bar is increased to accommodate the intermediate connection bus bar, then the three-layer structure can be formed, but spike voltage of the semiconductor switching element increases
Solution Approach 1:
The patent employs a four-layer bus bar structure where the first and second positive-electrode-side bus bars are arranged in parallel adjacent to the negative-electrode-side bus bar. This multi-dimensional arrangement creates shorter current paths and reduces the distance between opposing current flows, thereby reducing inductance and suppressing spike voltage.
Solution Approach 2:
By segmenting the positive-electrode-side connection into two parallel bus bars, the patent creates multiple current paths that are positioned closer to the negative-electrode-side bus bar. This segmentation enables shorter current loops and reduced inductance, effectively suppressing spike voltage without requiring increased bus bar spacing.
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 significantly reduces DC wiring inductances, suppressing spike voltage and preventing deterioration of semiconductor switching elements, while maintaining ease of production due to identical outer shapes of bus bars.
Implementation Method 1
DC wiring inductances of the power conversion device can be greatly reduced
Data Source
AI summary
Four bus bars, which are two positive-electrode-side bus bars connecting a positive electrode of a capacitor series circuit and a positive electrode of a power conversion section, a negative-electrode-side bus bar connecting a negative electrode of the capacitor series circuit and a negative electrode of the power conversion section, and an intermediate connection bus bar connecting in series two smoothing capacitors in the capacitor series circuit, are stacked in close contact with one another via insulating layers, to form a 4-layer bus bar. The two positive-electrode-side bus bars are not adjacent to each other and are connected in parallel to each other. The positive-electrode-side bus bar which is one of them and the negative-electrode-side bus bar are disposed adjacent to each other, thereby to reduce DC wiring inductances of the wiring structure in which the capacitor series circuit and the power conversion section are connected.