Capacitive DC-DC Converter Eliminates High-Cost Transformers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-cost transformers in existing DC-DC converters for high-voltage DC transmission limit cost-effectiveness, and the amplitude of circulating alternating current in capacitive coupling is not freely selectable due to the absence of inductive voltage conversion.
Innovation Solution
A DC-DC converter design using a coupling device with series-connected two-pole coupling modules comprising power semiconductor switches and capacitors for capacitive coupling, allowing flexible power exchange without transformers, and an additional parallel branch with capacitors and optional inductance to minimize AC components in DC currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transformer is used in the coupling device for inductive coupling of partial converters, then electromagnetic induction enables power transmission between converters, but the cost of the transformer increases significantly
Solution Approach 1:
The patent extracts and removes the transformer component from the coupling device, replacing the traditional inductive coupling mechanism with a purely capacitive coupling approach using coupling capacitors and circulating alternating current, thereby eliminating the high-cost transformer while maintaining power transmission capability
Solution Approach 2:
The patent changes the coupling mechanism from inductive (transformer-based) to capacitive (capacitor-based), fundamentally altering the physical parameter of the coupling device from magnetic field interaction to electric field interaction, which enables cost reduction while preserving functionality
2Ease of manufacture
If a purely capacitive coupling is used to reduce costs, then transformer costs are eliminated, but the amplitude of circulating alternating current cannot be freely selected due to absence of inductive voltage conversion
Solution Approach 1:
The patent introduces dynamic control of the circulating alternating current amplitude through the converter sections, enabling the system to adapt and optimize power exchange efficiency despite the fixed characteristics of capacitive coupling, thereby compensating for the loss of inductive voltage conversion flexibility
Solution Approach 2:
The patent employs control devices in the converter sections that monitor and adjust the circulating alternating current amplitude based on system conditions, creating a feedback mechanism that optimizes power transmission efficiency while maintaining the cost advantages of purely capacitive coupling
3Adaptability or versatility
If coupling modules with power semiconductor switches and capacitors are used, then flexible power exchange is enabled, but the device complexity increases compared to simple transformer coupling
Solution Approach 1:
The coupling modules serve multiple functions: they provide capacitive coupling between converter sections, enable flexible power exchange through controllable switches, and facilitate circulating alternating current for power transmission. This multi-functionality justifies the increased complexity by consolidating several functions into integrated modules
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 reduces costs by eliminating transformers and allows for efficient power exchange with adjustable circulating alternating current amplitude, optimizing power transmission in high-voltage DC applications.
Implementation Method 1
the coupling device provides a purely capacitive coupling of the partial converters. In other words, the power exchange between the partial converters takes place solely on the basis of an electrical capacitance that is provided by the coupling device
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a DC-to-DC converter (1) comprising a first partial converter (2) and a second partial converter (3) which are connected in series with one another to form a converter series circuit (4), wherein the converter series circuit (4) extends between a first and a second high-voltage side DC voltage pole (5, 6) and the second partial converter extends between a first and a second low-voltage side DC voltage pole (7, 8), wherein an AC voltage connection (14) of the first partial converter and an AC voltage connection (24) of the second partial converter are connected via a coupling device (32). The invention is characterized in that the coupling device (32) provides a purely capacitive coupling of the partial converters (2, 3).