Solid-State Transformer Architecture for Compact HV AC to LV DC Conversion
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Solution Overview
Problem
Conventional power conversion systems from high voltage (HV) or medium voltage (MV) AC to low voltage (LV) DC are bulky, consume significant resources, and incur power losses due to the use of large power transformers for galvanic insulation.
Innovation Solution
A power conversion system comprising a high voltage switchgear, a solid-state transformer with two modules for converting HV AC to LV DC, and a low voltage switchgear with multiple sub-modules for scalable and redundant power distribution, providing galvanic insulation and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power transformer is used for galvanic insulation in HV/MV AC to LV DC power conversion, then safety and galvanic insulation are achieved, but the system becomes bulky, occupies large space, consumes significant raw materials, and creates power losses
Solution Approach 1:
The patent changes the operating parameters by using high-frequency AC signals (typically 20 kHz to 1 MHz) instead of low-frequency power system frequencies (50/60 Hz). This parameter change enables the use of smaller magnetic components while maintaining galvanic insulation, directly resolving the contradiction between achieving insulation and minimizing space occupation
Solution Approach 2:
The patent replaces the conventional low-frequency electromagnetic transformer with a solid-state high-frequency transformer system. This substitution uses electronic switching devices (IGBTs, MOSFETs) to generate high-frequency AC, which then passes through a smaller high-frequency transformer for galvanic insulation, eliminating the need for bulky low-frequency transformers
2Reliability
If a conventional power transformer is used for galvanic insulation, then safety is achieved, but significant weight is created
Solution Approach 1:
By changing the operating frequency parameter to high-frequency range (20 kHz - 1 MHz), the magnetic component sizes and weights are dramatically reduced. The high-frequency transformer required for galvanic insulation weighs significantly less than a low-frequency power transformer, thus resolving the contradiction between safety and weight
Solution Approach 2:
The patent segments the power conversion function into multiple independent modules: high-voltage switches, high-frequency AC generation stage, high-frequency transformer for insulation, rectification stage, and control system. This modular segmentation allows the use of lightweight high-frequency components while maintaining safety functions
3Reliability
If a conventional power transformer is used, then galvanic insulation is achieved, but power losses increase
Solution Approach 1:
The patent changes the frequency parameter to high-frequency operation, which reduces copper losses and core losses in the transformer. High-frequency transformers operate more efficiently with lower hysteresis and eddy current losses, thereby resolving the contradiction between maintaining galvanic insulation and reducing power losses
Solution Approach 2:
The replacement of low-frequency electromagnetic transformation with high-frequency solid-state transformation reduces energy losses. The solid-state switching devices and high-frequency magnetic components exhibit lower losses compared to conventional low-frequency transformers, achieving both insulation and efficiency
4Reliability
If a conventional low-frequency power transformer is used, then galvanic insulation is provided, but the system consumes a lot of raw materials
Solution Approach 1:
By operating at high frequencies, the required amount of magnetic material and copper winding is dramatically reduced. The high-frequency transformer uses far less raw material while providing the same galvanic insulation function, thus resolving the contradiction between insulation and material consumption
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 system minimizes footprint, reduces material consumption, and enhances efficiency by enabling unidirectional and bi-directional power flow with improved safety and control, particularly suitable for renewable energy integration into MV distribution networks.
Implementation Method 1
The first module is configured to convert a high voltage alternating current 'HV AC' signal into a high voltage direct current 'HV DC' signal
Implementation Method 2
The second module is configured to connect to an output of the first module and convert the HV DC signal from the first module into at least one low voltage direct current 'LV DC' signal
Data Source
AI summary
A power conversion system includes a high voltage (HV) switchgear; a solid-state transformer; and a low voltage (LV) switchgear. The HV switchgear connects to and disconnects from a HV or medium voltage (MV) network. The HV switchgear connects to an input of the solid-state transformer. The solid-state transformer comprises a first module and a second module. The first module converts a HV alternating current (AC) signal into a HV direct current (DC) signal. The second module connects to an output of the first module and converts the HV DC signal from the first module into at least one LV DC signal. The second module comprises at least one sub-module that converts the HV DC signal from the first module into a LV DC signal. The LV switchgear connects to an output of the solid-state transformer.