On-board Power Conversion System with Capacitive Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
On-board power conversion systems for mobile transport vehicles face challenges in reducing volume while effectively filtering power variations at twice the frequency of the AC side, leading to increased costs, size, and reliability issues due to the need for large passive or active components.
Innovation Solution
The proposed system incorporates a medium voltage electric power conversion system with isolated DC-DC power conversion stages and a capacitive circuit between the transformer's intermediate point and the DC-AC primary converter, allowing for efficient magnetic coupling and reduced filtering requirements through a repetitive loop of operating phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large passive or active filtering components are used to filter power variations at twice the AC frequency, then power filtering performance is improved, but system volume and cost increase
Solution Approach 1:
The invention extracts and addresses only the twice-AC-frequency power variation component using a dedicated filtering stage, rather than using large filtering components for all power variations. This selective filtering approach reduces the required filter size while maintaining effectiveness for the specific problematic frequency component.
Solution Approach 2:
The invention changes the filtering approach by operating the filtering stage at a higher frequency (multiple times the AC frequency) rather than at the fundamental AC frequency. This parameter change allows smaller filtering components to achieve the same filtering effect, reducing overall system volume.
2Reliability
If voltage oversizing of DC side components is used to absorb power variations, then power variation absorption is improved, but component size and cost increase
Solution Approach 1:
The invention extracts the power variation absorption function from the main DC side components and implements it in a separate, dedicated filtering stage. This allows the main components to be sized for average power handling while the filtering stage handles the variations, reducing overall component size and weight.
Solution Approach 2:
The invention uses periodic switching at a frequency multiple times higher than the AC frequency to absorb and manage power variations. This high-frequency periodic action allows smaller components to handle the same power variation energy, reducing component size and weight.
3Reliability
If specific filtering for twice AC frequency is implemented, then power variation filtering is improved, but device complexity increases
Solution Approach 1:
The invention merges the filtering function with the existing power conversion architecture by integrating a filtering stage that operates in conjunction with the AC-DC conversion stages. This unified approach achieves specific twice-frequency filtering without adding completely separate complex filtering systems.
Solution Approach 2:
The filtering stage is designed to perform multiple functions: it filters twice-AC-frequency variations, enables voltage transformation between different DC levels, and provides galvanic isolation. This multi-functionality reduces overall system complexity by combining what could be separate systems into one integrated stage.
4Power
If multiple conversion slices are used to handle medium voltage, then voltage handling capability is improved, but system volume increases
Solution Approach 1:
The invention nests multiple conversion slices within a compact modular architecture where each slice contains an AC-DC stage and a DC-DC filtering stage. This nested arrangement allows efficient space utilization and reduces overall system volume compared to distributed arrangements.
Solution Approach 2:
The invention changes the operating frequency parameter of the DC-DC conversion stage to operate at a frequency multiple times higher than the AC frequency. This parameter change allows smaller magnetic components and reduced volume while maintaining the required power handling capability across multiple slices.
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 solution reduces the volume of the system by effectively managing power variations, minimizing the need for bulky filtering components and enhancing reliability and cost-effectiveness.
Implementation Method 1
a transformer (36B) having a primary winding, connected to the downstream side of the primary converter and a secondary winding, downstream
Data Source
Figure 1
Figure 2
Figure 3~4D
AI summary
The invention relates to an on-board system and a method for converting medium-voltage electrical power for a movable transport vehicle (10), comprising a plurality of conversion blocks (38.i) each having an upstream AC-DC stage (34) and an isolated downstream DC-DC stage (36), of the type in which, for each conversion block (38.i), the isolated downstream DC-DC power conversion stage (36) comprises a primary DC-AC converter (36A) produced in the form of a full bridge of controlled electronic switches and a transformer (36B) having a primary winding (36B1), connected to the downstream side of the primary converter and a secondary winding; characterised in that, for each conversion block (38.i), the primary DC-AC converter (36A) comprises a capacitive circuit (56) electronically inserted between an intermediate point (54) of the primary winding of the transformer (36B) and one side (48, 50) of the full bridge of the primary DC-AC converter (36A).