Modular Static Transfer Switch Using Wide-Bandgap Transistor Paralleling
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Solution Overview
Problem
Existing static transfer switches (STS) lack modularity, requiring different thyristor power modules and heatsink assemblies for various current ratings, leading to logistical and supply chain challenges. Thyristors are prone to thermal runaways and cannot be used in parallel or turned off before external current reversal, which is undesirable in mission-critical systems.
Innovation Solution
A modular static transfer switch assembly using wide-bandgap transistors, such as MOSFETs, JFETs, or IGBTs, organized in individual assemblies that can be connected in parallel to achieve higher current ratings. The assembly includes a controller for transferring power between sources, a galvanic isolator for disconnecting faulty modules, and an N+1 redundancy for maintaining operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thyristors are used in existing STS designs, then the device can handle high current ratings, but the device lacks modularity and requires different power modules for different current ratings
Solution Approach 1:
The STS device is divided into modular units, each containing a semiconductor powertrain with wide-bandgap transistors. These modules can be connected in parallel to achieve different current ratings, eliminating the need for completely different designs for 200A/250A, 400A, and 600A ratings.
Solution Approach 2:
A universal modular design is implemented where the same semiconductor powertrain module can be used across different current ratings by simply changing the number of modules connected in parallel. This single modular design serves multiple current rating requirements (200A/250A, 400A, 600A).
2Power
If thyristors are connected in parallel to increase current capacity, then the current rating increases, but thermal runaway occurs due to negative temperature coefficient
Solution Approach 1:
The patent changes the semiconductor material parameter from conventional silicon-based thyristors to wide-bandgap transistors (SiC MOSFETs, GaN HEMTs). These wide-bandgap devices have positive temperature coefficient characteristics, enabling stable parallel operation without thermal runaway while maintaining high current capacity.
3Ease of operation
If thyristors are used, then the device can conduct current, but the device cannot be turned off before external current reversal
Solution Approach 1:
The patent replaces the mechanical/physical limitation of thyristor turn-off (which requires external current reversal) with electronically controllable wide-bandgap transistors. These transistors can be turned off immediately by removing the gate signal, providing full controllability and eliminating turn-off delay.
4Power
If different thyristor power modules are used for different current ratings, then the current rating requirement is met, but logistics and supply chain burden increases
Solution Approach 1:
The STS is segmented into standardized modular units that can be combined in different quantities to meet various current rating requirements. This segmentation into uniform modules simplifies manufacturing, inventory management, and supply chain logistics compared to maintaining completely different designs for each current rating.
Data Source
AI summary
A modular static transfer switch (STS) assembly comprises a semiconductor powertrain constructed with wide-bandgap transistors. A first input of the STS assembly is electrically coupled to a first power source and a second input of the STS assembly is electrically coupled to a second power source. An output of the STS assembly is electrically coupled to a load, wherein the load is powered using the first power source via the STS modular assembly. A galvanic isolator like relay or contactor or breaker or fuse disconnects any faulty semiconductor powertrain. The STS also comprises a controller to execute the transfer of power supplied to the load from the first power source to the second power source by electrically decoupling the first power source from the load, verifying that the first power source is disconnected from the load, and providing instructions to electrically couple the second power source to the load.