SiC Power Module Switching Loss Reduction
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Solution Overview
Problem
High-power electronic devices using silicon carbide (SiC) face challenges such as forward voltage degradation due to Basal Plane Dislocations and increased on-resistance at higher blocking voltages, leading to excessive power dissipation and limited switching frequencies, especially at high temperatures.
Innovation Solution
A power module design utilizing majority carrier devices formed from a wide bandgap material system, specifically SiC MOSFETs and Schottky diodes, arranged in configurations like the six-pack module, which reduces switching losses and allows for higher switching frequencies without additional circuitry, enabling efficient and cost-effective high-power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If bipolar devices are used to reduce drift layer resistance via conductivity modulation, then forward voltage is reduced, but forward voltage degradation occurs over time due to Basal Plane Dislocations in SiC
Solution Approach 1:
The patent extracts the problematic bipolar operation mechanism that causes forward voltage degradation due to BPDs and replaces it with unipolar MOSFET operation. The MOSFET structure eliminates the drift layer conductivity modulation mechanism that is susceptible to BPD-related degradation, thereby removing the source of forward voltage instability while maintaining low forward voltage through optimized drift layer design.
Solution Approach 2:
The patent changes the operational parameters by transitioning from bipolar to unipolar device operation. This fundamental parameter change in the conduction mechanism allows the device to achieve low forward voltage through different physical principles (field effect control rather than minority carrier injection) that are not affected by BPD-related degradation mechanisms.
2Power
If blocking voltage is increased to handle higher power applications, then power handling capability is improved, but on-resistance increases substantially due to increased drift layer thickness
Solution Approach 1:
The patent utilizes SiC wide bandgap material to create a composite semiconductor structure that enables high blocking voltage operation with lower on-resistance compared to traditional Si-based devices. The SiC material's superior breakdown field and carrier mobility allow the drift layer to simultaneously achieve high voltage blocking capability and low resistance, resolving the trade-off between power handling and conduction losses.
3Power
If drift layer thickness is increased to achieve higher blocking voltage, then voltage blocking capability is improved, but power dissipation increases due to bulk mobility reduction at high temperatures
Solution Approach 1:
The patent changes the material parameter from traditional Si to SiC wide bandgap material, which fundamentally alters the temperature dependence of carrier mobility. SiC's superior thermal properties and higher saturation velocity allow the device to maintain low on-resistance even at high temperatures and thick drift layers, enabling high voltage blocking capability without excessive power dissipation in harsh thermal environments.
Data Source
AI summary
The present disclosure relates to a power module that has a housing with an interior chamber and a plurality of switch modules interconnected to facilitate switching power to a load. Each of the plurality of switch modules comprises at least one transistor and at least one diode mounted within the interior chamber and both the at least one transistor and the at least one diode are majority carrier devices, are formed of a wide bandgap material system, or both. The switching modules may be arranged in virtually any fashion depending on the application. For example, the switching modules may be arranged in a six-pack, full H-bridge, half H-bridge, single switch or the like.