Solid-State Transformer Power Conversion for Fast EV Charging
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Solution Overview
Problem
Conventional high-power EV charging stations face issues with heavy, bulky line-frequency transformers, high standby iron loss, and low efficiency due to multiple stages of power conversion, which hinder flexible and efficient high-voltage and high-current charging.
Innovation Solution
A power conversion system for solid state transformers comprising a DC link with capacitors and power conversion module assemblies, where input sides are connected in series and output sides in parallel or series, to provide flexible and efficient power supply configurations, and a charging system that includes an AC-to-DC conversion circuit coupled with the power conversion system to meet high-voltage and high-current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a line-frequency transformer is used for power conversion, then voltage transformation can be achieved, but the transformer becomes heavy and bulky
Solution Approach 1:
The patent replaces the traditional line-frequency transformer (a mechanical/electromagnetic device) with a solid-state power conversion system using DC conversion modules, capacitors, and semiconductor switches. This substitution eliminates the heavy iron core and windings of conventional transformers, achieving voltage transformation through electronic switching and capacitor voltage division, thereby dramatically reducing weight and volume while maintaining power transformation capability.
2Power
If a line-frequency transformer is used, then voltage transformation is possible, but standby iron loss increases
Solution Approach 1:
The patent replaces the transformer with a solid-state power conversion system that uses DC conversion modules with capacitive voltage transformation. This eliminates the iron core completely, removing the source of standby iron loss. The system achieves voltage transformation through semiconductor switching and capacitor voltage division, resulting in minimal energy loss during standby operation.
3Adaptability or versatility
If multiple stages of power conversion are used, then voltage and current can be adjusted, but system efficiency decreases
Solution Approach 1:
The patent combines multiple power conversion functions into a single integrated solid-state system. The DC conversion modules, capacitors, and control circuitry work together in one unified architecture to simultaneously achieve voltage transformation, current regulation, and power factor correction. This integration eliminates the need for separate transformer and power converter stages, reducing cumulative energy losses while maintaining full power adjustment flexibility.
4Power
If a conventional power system with transformer and multiple converters is used, then power conversion can be achieved, but device complexity increases
Solution Approach 1:
The patent integrates the transformer function, power conversion, and voltage regulation into a single solid-state system. The DC conversion modules with series-connected capacitors perform both voltage transformation and power conversion in one unified structure, eliminating the need for separate transformer and converter components. This integration significantly simplifies the overall system architecture while maintaining full power conversion capability.
Solution Approach 2:
The solid-state power conversion system performs multiple functions simultaneously: voltage transformation, current regulation, power factor correction, and protection. The DC conversion modules and control circuitry are designed to handle various operating conditions and power levels, making the system universally applicable to different charging power requirements without needing additional specialized 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
The solution enhances the flexibility and reliability of electric vehicle charging, increases efficiency, and supports fast charging with improved safety by reducing weight, iron loss, and the number of power conversion stages.
Implementation Method 1
A DC link is provided, a plurality of capacitors are coupled in series between the positive bus and the negative bus
Implementation Method 2
Each of the power conversion module assemblies includes a plurality of DC conversion modules
Data Source
AI summary
A power conversion system applied to a solid state transformer includes a DC link, a plurality of capacitors, and a plurality of power conversion module assemblies. The plurality of capacitors is coupled in series between a positive bus and a negative bus of the DC link. Each of the power conversion module assemblies has a plurality of DC conversion modules. In any of the power conversion module assemblies, input sides of the DC conversion modules are connected in series to form two input ends of the power conversion module assembly, and output sides of the DC conversion modules are connected in parallel to form two output ends of the power conversion module assembly. Each of the plurality of power conversion module assemblies is correspondingly connected to each of the plurality of capacitors.