DC Bus Arrangement for Oscillation Dampening in Frequency Converters
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Solution Overview
Problem
High power density in frequency converters leads to resonance currents due to interconnected capacitances, causing extra power losses and warming of components, particularly when resonance frequency matches the switching frequency of the inverter unit.
Innovation Solution
A compact liquid-cooled power electronics device design where the DC bus current conductors are arranged apart from each other by a thin insulating layer on a metal frame, inducing eddy currents that dampen resonance oscillations and increase serial resistance, reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If DC bus current conductors are arranged close together to minimize inductivity and power losses, then power losses are reduced, but resonance oscillations are amplified
Solution Approach 1:
The patent converts the harmful resonance oscillations into a beneficial effect by deliberately arranging the DC bus current conductors to form a resonant LC circuit with the capacitances. The resonance is designed to occur at a frequency that dampens the harmful high-frequency disturbance signals, transforming the previously harmful resonance into a useful filtering mechanism that reduces electromagnetic interference without requiring additional external components.
Solution Approach 2:
The patent merges the DC bus current conductors with the metal frame structure by arranging the conductors on opposite sides of the frame and connecting them to form a closed loop. This integration combines the structural support function of the metal frame with the electrical function of the DC bus, creating a compact design that provides both mechanical support and electromagnetic interference filtering without requiring separate components.
2Object-affected harmful factors
If DC bus current conductors are arranged apart from each other to dampen resonance oscillations, then resonance is reduced, but serial resistance increases and power losses increase
Solution Approach 1:
The patent merges the DC bus current conductors with the metal frame structure by arranging the conductors on opposite sides of the frame and connecting them to form a closed loop. This integration combines the structural support function of the metal frame with the electrical function of the DC bus, creating a compact design that provides both mechanical support and electromagnetic interference filtering without requiring separate components.
Solution Approach 2:
The patent replaces traditional electrical damping components (such as external resistors or complex filtering circuits) with a mechanically integrated solution using the metal frame structure. The frame serves as both the mechanical support and the electrical pathway, eliminating the need for additional damping components and reducing overall device complexity while maintaining effective resonance dampening.
3Loss of energy
If traditional DC bus arrangement is used with conductors arranged to minimize resistivity, then power losses are minimized, but resonance current causes extra power losses and component warming
Solution Approach 1:
The patent converts the harmful resonance oscillations into a beneficial effect by deliberately arranging the DC bus current conductors to form a resonant LC circuit with the capacitances. The resonance is designed to occur at a frequency that dampens the harmful high-frequency disturbance signals, transforming the previously harmful resonance into a useful filtering mechanism that reduces electromagnetic interference without requiring additional external components.
Solution Approach 2:
The patent merges the DC bus current conductors with the metal frame structure by arranging the conductors on opposite sides of the frame and connecting them to form a closed loop. This integration combines the structural support function of the metal frame with the electrical function of the DC bus, creating a compact design that provides both mechanical support and electromagnetic interference filtering without requiring separate components.
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 design effectively dampens resonance oscillations without external components, allowing for a compact and cost-effective solution that minimizes power losses and maintains filtering functionality.
Implementation Method 1
the DC bus current conductors are arranged apart from each other by a thin insulating layer on a metal frame, inducing eddy currents that dampen resonance oscillations
Implementation Method 2
inducing eddy currents that dampen resonance oscillations and increase serial resistance, reducing power losses
Data Source
AI summary
Power electronics device, such as a frequency converter, comprising power units (REC1, INU1, INU2, CDC1), a metal frame (31) and a DC bus arrangement in which the power units are connected. The power units may be assembled inside the metal frame (31) wherein the shape of the metal frame is elongated with rectangular cross-sectional shape, consisting of a bottom part (33) and from that essentially vertical oriented side wall parts (32). The DC bus arrangement is arranged on top of the bottom part (33) of the metal frame (31) and separated by an insulator layer (S1) from the metal frame (31). The DC bus arrangement comprises a first DC bus current conductor (DC+) and a second DC bus current conductor (DC−) which are arranged apart from each other. The DC bus current conductors (DC+, DC−) have a flat shape in such a way that their thickness dimension is essentially shorter than their width dimension.