Local TVS for SSPC Parasitic Inductance Management
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Solution Overview
Problem
In multi-semiconductor solid state power controllers (SSPCs), the distributed parasitic inductance between transient voltage suppressors (TVSs) and switching devices can cause avalanche breakdown due to high voltage transients, which existing protection circuits fail to manage effectively, leading to potential damage.
Innovation Solution
The implementation of smaller local TVS devices in parallel with switching devices and parasitic inductances, along with main TVS devices, to dissipate energy stored in parasitic inductances, thereby reducing the risk of avalanche breakdown and optimizing performance while minimizing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple semiconductor devices are used to increase current ratings, then power handling capability is improved, but distributed parasitic inductance increases causing voltage transients
Solution Approach 1:
The protection system is segmented into multiple TVS devices: main TVS devices for bulk transient suppression and local TVS devices for targeted parasitic inductance compensation near each switching device. This segmentation allows each TVS to be optimally positioned and sized for its specific function, reducing overall voltage transients while handling high power.
Solution Approach 2:
Local TVS devices act as intermediary protection elements between the switching devices and main TVS devices. They specifically target and suppress voltage transients generated by parasitic inductances in their local vicinity, preventing these transients from propagating to switching devices while allowing main TVS to handle bulk transient energy.
2Reliability
If main TVS devices are used for voltage clamping, then protection coverage is improved, but parasitic inductance of TVS allows voltage greater than clamp voltage across switching devices
Solution Approach 1:
Different TVS devices are deployed with different characteristics: main TVS devices provide bulk voltage clamping with higher power handling, while local TVS devices provide targeted voltage suppression near switching devices with lower parasitic inductance. This local quality differentiation ensures that switching devices receive adequate protection from both distributed and localized TVS elements.
Solution Approach 2:
The protection architecture transitions from a single-dimension (bulk TVS only) to a two-dimensional approach by adding local TVS devices in parallel with main TVS devices. This creates a hierarchical protection structure where local TVS handles fast, localized transients and main TVS handles slower, bulk transients, effectively covering multiple transient response dimensions.
3Object-affected harmful factors
If more TVS devices are added to reduce parasitic inductance effects, then transient management is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using a single large TVS device that would require high power rating and have high parasitic inductance, the solution uses multiple smaller TVS devices. Each local TVS device handles only the transient energy from its associated switching device's parasitic inductance, providing sufficient protection with lower individual power ratings and lower parasitic inductance values.
Solution Approach 2:
Multiple lower-cost, lower-power-rated local TVS devices are used instead of a single expensive, high-power-rated TVS device. Each local TVS device is simpler and cheaper individually, and their combined effect provides superior transient management. The distributed architecture allows using less expensive components that collectively achieve the protection goal.
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 approach effectively manages transients in SSPCs by dissipating energy stored in parasitic inductances, preventing damage to switching devices and reducing the number of TVS devices required, thus optimizing performance and reducing unit costs.
Implementation Method 1
Each of the plurality of local TVSs is connected in parallel with the series combination of the switching device and at least one parasitic inductance of the plurality of parasitic inductances to dissipate energy stored within the at least one parasitic inductor
Data Source
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AI summary
Provided is a method and system that includes a solid state power controller system (200) comprising a plurality of switching devices (220) connected in parallel for performing switching; one or more main transient voltage suppressors (230) configured to perform voltage clamping; a plurality of parasitic inductances (234a-234d), each connected in series with a switching device of the plurality of switching devices (220); a plurality of local transient voltage suppressors (236a-236c), each connected with a respective switching device (220) of the plurality of switching devices (220) and configured to dissipate energy stored within at least one parasitic inductance (234a-234d) of the plurality of parasitic inductances (234a-234d); and a plurality of bias resistors (235a-235c), each connected with a respective switching device (220) of the plurality of switching devices (220); wherein each local transient voltage suppressor (236a-236c) of the plurality of local transient voltage suppressors (236a-236c) is connected in series with a respective bias resistor (235a-235c) of the plurality of bias resistors (235a-235c).