Grounding System for Semiconductor Modules in Variable Speed Drives
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Solution Overview
Problem
Plastic heat sinks used in variable speed drives for HVAC&R applications can cause parasitic currents and electrical charges to build up, interfering with control signals and leading to malfunction or damage due to the lack of grounding, which is not effectively addressed by existing technologies.
Innovation Solution
A grounding system is introduced that connects the base of semiconductor modules to earth ground or a suitable voltage reference point through conductive layers, preventing electrical charge accumulation and reducing parasitic currents, thereby eliminating shoot-through currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic heat sinks are used to reduce material costs, then manufacturing cost is reduced, but parasitic currents and electrical charges build up causing malfunction
Solution Approach 1:
A grounding system with conductive elements is introduced as an intermediary between the plastic heat sink and the semiconductor module base. This mediator provides a path for electrical charges to dissipate to ground potential, preventing charge accumulation and parasitic current formation while maintaining the cost advantages of plastic heat sinks.
Solution Approach 2:
The electrical properties of the heat sink system are modified by adding conductive grounding elements. This changes the electrical parameter of the plastic heat sink from completely insulating to having a controlled path to ground, thereby preventing charge buildup while maintaining the mechanical and thermal benefits of plastic material.
2Ease of manufacture
If nonconductive heat sinks are used to reduce material costs, then manufacturing cost is reduced, but parasitic currents interfere with control signals
Solution Approach 1:
The grounding system acts as an intermediary that provides a controlled path for parasitic currents to safely discharge to ground. This prevents the parasitic currents from interfering with control signals while maintaining the cost benefits of nonconductive plastic heat sink material.
Solution Approach 2:
The grounding system converts the potentially harmful effect of charge accumulation in plastic heat sinks into a beneficial controlled discharge path. By providing a dedicated grounding path, the system transforms what would be dangerous parasitic currents into controlled, harmless current flow to ground potential.
3Ease of manufacture
If semiconductor modules are mounted on plastic heat sinks, then material costs are reduced, but electrical charges accumulate between base and conductive layers
Solution Approach 1:
The grounding system introduces conductive elements as intermediaries between the semiconductor module base and ground. These intermediaries provide a path for electrical charges to dissipate, preventing charge accumulation between the base and conductive layers while maintaining the cost advantages of plastic heat sinks.
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 grounding system effectively reduces parasitic currents and electrical charges, ensuring safe and reliable operation of semiconductor modules by preventing accidental switching and potential damage to the modules and other electronic components.
Implementation Method 1
A grounding system is introduced that connects the base of semiconductor modules to earth ground or a suitable voltage reference point through conductive layers, preventing electrical charge accumulation and reducing parasitic currents
Data Source
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AI summary
A grounding system for a semiconductor module of a variable speed drive includes a first conductive layer, a second conductive layer; a substrate disposed between the first conductive layer and the second conductive layer; and a base attached to the second conductive layer, the base being connected to earth ground via a grounding harness. The first conductive layer is in electrical contact with the semiconductor module and the substrate, and electrically insulated from the second conductive layer by the substrate. The second conductive layer is in electrical contact with the substrate and disposed between the substrate and the base in electrical communication with an earth ground. The first conductive layer, the substrate and the second conductive layer form a capacitance path between the semiconductor module and the base as well as electrical conductors and the base for reduction circulating currents within the semiconductor module.