Power Conversion Apparatus Bus Bar Impedance Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion apparatuses, such as inverter systems, face challenges in reducing the load on capacitors and minimizing their size while effectively managing surge currents and ripple currents, as they struggle to balance impedance between power modules and capacitors, leading to increased capacitor size and potential overheating.
Innovation Solution
The apparatus employs a bus bar configuration that creates inter-phase current paths with lower impedance than intra-phase current paths, allowing for increased cancellation of ripple currents between power modules and reduced current flow to capacitors, thereby minimizing capacitor size and preventing surge currents from reaching power modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitors are arranged with low impedance connection to power modules, then surge voltage absorption is improved, but capacitor size increases and load on capacitors increases
Solution Approach 1:
The invention divides the capacitor arrangement into multiple units, each associated with a specific power module. Instead of using a single large capacitor or fewer capacitors with high individual loads, the system segments the capacitance distribution to balance the load across multiple smaller capacitor units. This segmentation allows each capacitor to handle a reduced individual load while collectively providing the necessary surge voltage absorption capability.
Solution Approach 2:
The invention applies different impedance characteristics to different current paths: the inter-phase current path is designed with lower impedance for ripple current circulation, while the intra-phase current path to capacitors has higher impedance. This local differentiation of impedance quality allows ripple currents to circulate locally between power modules without overloading capacitors, reducing the load on capacitors while maintaining effective surge voltage absorption.
2Object-affected harmful factors
If wiring between capacitors and power modules is made short, then wiring inductance is reduced and surge voltages are lowered, but the load on capacitors is not reduced and capacitor size cannot be minimized
Solution Approach 1:
The invention segments the current circulation paths by creating distinct inter-phase current paths between power modules and intra-phase current paths to capacitors. This segmentation allows ripple currents to circulate through the inter-phase paths without necessarily flowing through the capacitor connections, reducing the effective load on capacitors even with short wiring that minimizes inductance for surge voltage protection.
Solution Approach 2:
The invention creates local current circulation loops between adjacent power modules through inter-phase current paths with lower impedance. This local quality differentiation allows ripple currents to be handled locally between power modules rather than being forced through the capacitor paths, reducing capacitor load while maintaining short wiring for surge voltage management.
3Volume of stationary object
If power modules are arranged radially around direct current input section, then compactness is improved, but impedance balance between power modules and capacitors deteriorates, leading to increased capacitor load
Solution Approach 1:
The invention applies different impedance design characteristics to different current paths within the radial arrangement. The inter-phase current paths between radially arranged power modules are designed with lower impedance to facilitate ripple current circulation, while the intra-phase current paths to capacitors have higher impedance. This local quality differentiation maintains impedance balance even in the compact radial configuration, preventing excessive capacitor load.
Solution Approach 2:
The invention segments the impedance characteristics by path type within the radial arrangement, creating distinct impedance profiles for inter-phase versus intra-phase current paths. This segmentation allows the compact radial layout to be maintained while ensuring that ripple currents preferentially flow through the lower impedance inter-phase paths rather than overloading the capacitors through the intra-phase paths.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power conversion apparatus (1) includes a plurality of power modules (2,3,4), a plurality of capacitors (5,6,7) and a bus bar (8). Each of the power modules has a direct current terminal section and an alternating current terminal section. Each of the power modules is configured and arranged to convert a direct current inputted from the direct current terminal section into a respective phase of a multiple-phase alternating current and to output the multiple-phase alternating current to the alternating current terminal section. Each of the capacitors is arranged with respect to a corresponding one of the power modules. The bus bar forms an inter-phase current path between the power modules that are adjacent and forms an intra-phase current path between one of the power modules and a corresponding one of the capacitors such that an impedance of the inter-phase current path is smaller than an impedance of the intra-phase current path.