EV Charging System Using LIT Rectifier and Medium-Frequency Transformer
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Solution Overview
Problem
Charging systems for electric vehicles require high power levels, leading to bulky frontends due to the need for large and expensive 50 Hz transformers, which increases manufacturing costs and footprint, while also necessitating galvanic insulation and efficient power delivery across multiple charging poles.
Innovation Solution
A charging system utilizing a Line Interphase Transformer (LIT)-based rectifier to convert AC medium-voltage power into medium-voltage DC, followed by a modular DC/DC converter with large step-down gain to produce high-frequency AC, and a Medium-Frequency Transformer (MFT) to transform this signal into low-voltage high-frequency AC for efficient power delivery to charging boxes, eliminating the need for large 50 Hz transformers and providing galvanic insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large 50 Hz transformers are used to deliver high power levels, then power delivery capability is improved, but system size and manufacturing cost increase
Solution Approach 1:
The patent changes the operating frequency parameter from 50 Hz to medium frequency (MF) range, and transforms the power conversion architecture from direct 50 Hz transformation to a multi-stage process involving rectification to DC, inversion to MF-AC, and then transformation. This parameter change enables the use of much smaller transformers while maintaining high power delivery capability.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic 50 Hz transformation system with an electronic power conversion system consisting of LIT-based rectifier, modular DC/DC converter, and MFT. This substitution eliminates the need for large 50 Hz transformers by using electronic switching and control mechanisms.
2Power
If large 50 Hz transformers are used for high power delivery, then power transmission capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the power conversion function into three independent modular units: LIT-based rectifier, modular DC/DC converter, and MFT. Each module can be manufactured, tested, and replaced independently, reducing overall manufacturing cost and improving ease of production compared to a single large 50 Hz transformer system.
Solution Approach 2:
By changing from 50 Hz operation to medium frequency operation, the patent enables the use of smaller, less expensive transformer components. The MFT at medium frequency requires significantly less core material and winding than a 50 Hz transformer of equivalent power rating, thereby reducing manufacturing cost.
3Productivity
If multiple charging poles are deployed to serve multiple vehicles, then charging capacity is improved, but frontend system complexity increases
Solution Approach 1:
The patent employs multiple independent charging boxes, each with its own MFT and power conversion chain. This segmentation allows each charging pole to operate independently with standardized modular components, simplifying the frontend system architecture compared to shared large-scale power conversion equipment.
Solution Approach 2:
The modular power conversion system with LIT-based rectifier, DC/DC converter, and MFT serves as a universal frontend architecture that can support multiple charging poles and different charging standards. This multi-functional design reduces overall system complexity by using the same core technology platform across multiple charging points.
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
The solution results in a compact, cost-effective, and low-loss charging system capable of delivering high power efficiently, compliant with electrical standards and legal requirements, while allowing for scalable and flexible power distribution across multiple charging poles.
Implementation Method 1
a LIT-based rectifier (LIT: Line Interphase Transformer), configured for connecting an input of the LIT-based rectifier to an AC medium-voltage power signal and for outputting a medium-voltage DC-signal
Implementation Method 2
a modular DC/DC converter with large step-down gain, configured for transforming the medium-voltage DC-signal into a medium-voltage HF-AC-signal
Implementation Method 3
a medium-frequency transformer, MFT, configured for transforming the medium-voltage HF-AC-signal into a low-voltage HF-AC-signal for the at least one charging box (HF: high frequency)
Data Source
AI summary
A charging system for electric vehicles includes a line interphase transformer, LIT-based rectifier configured for connecting an input of the LIT-based rectifier to an AC medium-voltage power signal and for outputting a medium-voltage DC-signal; a modular DC/DC converter with large step-down gain is configured for transforming the medium-voltage DC-signal into a medium-voltage HF-AC-signal; and a medium-frequency transformer, MFT, is configured for transforming the medium-voltage HF-AC-signal into a low-voltage HF-AC-signal for the at least one charging box.