Inverter Module Busbar Layout for Balanced Current Sharing
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Solution Overview
Problem
Conventional inverter designs experience unbalanced current sharing between power units due to different impedances caused by the connection of DC sides with a DC support capacitor cell module through two bus-bars, leading to inefficiencies and increased complexity.
Innovation Solution
The inverter module addresses this by connecting the positive poles of DC sides equidistantly with a capacitor head terminal, negative poles with a capacitor end terminal, and midpoints with a capacitor midpoint, using integrated conductive bars to ensure balanced current sharing and reduced parasitic inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC sides of power units are connected with DC support capacitor cell module through capacitor bus-bar and power bus-bar, then electrical connection is established, but impedances between capacitor module and individual power units become different resulting in unbalanced current sharing
Solution Approach 1:
The patent applies equipotentiality by connecting the positive poles of all power units to the positive terminal of the DC support capacitor through a common positive bus-bar, and negative poles to the negative terminal through a common negative bus-bar. This ensures all power units experience equal impedance and achieve balanced current sharing, eliminating the unbalanced current distribution problem caused by different connection distances in conventional designs.
Solution Approach 2:
The patent merges the positive bus-bar and negative bus-bar into an integrated bus-bar structure that simultaneously provides electrical connection for multiple power units. This consolidation simplifies the connection structure by reducing the number of separate connection components while maintaining balanced impedance across all power units, thus resolving both current sharing balance and device complexity issues.
2Ease of manufacture
If different connection distances are used for DC sides of power units to capacitor potentials, then connection is simplified, but unbalanced current sharing occurs between power units
Solution Approach 1:
The patent ensures equipotential connection by designing the bus-bar structure such that all power units are connected to the same potential points (positive and negative terminals of the DC support capacitor) through equal impedance paths. This maintains balanced current sharing while allowing flexible physical arrangement of power units, thus achieving both ease of manufacture and current sharing balance.
3Device complexity
If conventional two bus-bar connection method is used, then connection structure is established, but parasitic inductance and connection points are increased
Solution Approach 1:
The patent merges the positive and negative bus-bars into an integrated bus-bar structure where multiple power units are connected in parallel between the same two potential points. This reduces the total number of separate connection components and minimizes parasitic inductance by shortening current paths, while maintaining balanced impedance for current sharing.
Solution Approach 2:
The patent extracts and eliminates unnecessary intermediate connection points and redundant bus-bar segments from the conventional design. By directly connecting all power units to the terminal points of the DC support capacitor through streamlined bus-bars, the design removes excess connection points that contribute to parasitic inductance, thus reducing harmful factors while simplifying the overall connection structure.
Data Source
AI summary
An inverter module and an inverter are provided. The inverter module includes at least two capacitors and at least one power unit group. The at least one power unit group each comprises one or more power units. The capacitors are connected in series and parallel to form a capacitor head terminal, a capacitor end terminal and a capacitor midpoint, where capacitance between the capacitor midpoint and the capacitor head terminal is the same as capacitance between the capacitor midpoint and the capacitor end terminal. Positive poles of DC sides of the power units are equidistantly connected with the capacitor head terminal, negative poles of the DC sides of the power units are equidistantly connected with the capacitor end terminal, and midpoints of the DC sides of the power units are equidistantly connected with the capacitor midpoint.