DC bus capacitor assemblies for vienna VFD in air conditioning systems
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Solution Overview
Problem
Existing air conditioning system drives require large capacitance between the AC-DC converter and DC-AC inverter, resulting in a large footprint and weight due to the need for substantial capacitors.
Innovation Solution
The drive incorporates a Vienna rectifier with separate converter and inverter assemblies, where the inverter capacitance is electrically parallel to the converter capacitance, allowing for smaller capacitors and a reduced overall capacitance requirement, thereby minimizing the drive's footprint and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large capacitance is used between the AC-DC converter and DC-AC inverter, then the filtering and decoupling performance is improved, but the drive footprint and weight increase
Solution Approach 1:
The patent divides the capacitance into two separate parts: converter capacitance (C1, C2) integrated with the Vienna rectifier and inverter capacitance (C3) integrated with the DC-AC inverter. This segmentation allows each capacitor to be optimized for its specific function and reduces the total capacitance required compared to a single large capacitor, thereby reducing drive weight while maintaining filtering and decoupling performance.
2Reliability
If large capacitance is used between the AC-DC converter and DC-AC inverter, then the filtering and decoupling performance is improved, but the drive footprint increases
Solution Approach 1:
The patent segments the capacitance into converter capacitance (C1, C2) and inverter capacitance (C3) that are physically integrated with their respective assemblies. This segmentation eliminates the need for a single large capacitor, reducing the overall footprint of the drive while maintaining the required filtering and decoupling performance.
Solution Approach 2:
The patent merges the capacitance functions directly into the converter and inverter assemblies by integrating capacitors C1 and C2 with the Vienna rectifier and capacitor C3 with the DC-AC inverter. This merging eliminates the need for separate large capacitor components, thereby reducing the drive footprint while maintaining functional performance.
3Area of stationary object
If separate converter and inverter assemblies are used, then the drive footprint is reduced, but the system complexity increases
Solution Approach 1:
The patent combines the capacitance functions directly into the converter and inverter assemblies, merging multiple functions into integrated units. This merging approach reduces the overall system footprint while managing complexity through functional integration rather than separate discrete 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 configuration reduces the drive's size and weight while maintaining effective power conversion, achieving a more compact and efficient air conditioning system drive.
Implementation Method 1
A capacitance is used between the AC-DC converter and a DC-AC inverter to filter the DC output voltage decouple the AC-DC converter and a DC-AC inverter
Data Source
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AI summary
A drive for an air conditioning system includes a converter assembly including a Vienna rectifier having a converter capacitance across a positive DC bus and a negative DC bus; and an inverter assembly including an inverter capacitance across the positive DC bus and the negative DC bus, the inverter capacitance in electrical parallel with the converter capacitance; wherein the converter assembly and the inverter assembly are physically separate assemblies.