Half-Bridge Power Module Gate Short-Circuit Switching
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Solution Overview
Problem
In half-bridge output circuits, the rapid rise in drain-to-source voltage of MOSFETs leads to displacement currents that cause gate-to-source voltage increases, potentially turning on the MOSFETs and resulting in penetration currents, especially when one MOSFET is turned on while the other is off.
Innovation Solution
Incorporating gate short-circuit switching devices between the gate and source of each MOSFET, which short-circuit the gate-to-source portion when the other MOSFET is turned on, preventing the rise in gate-to-source voltage and reducing the size of the power module by mounting these devices on the same substrate and using SiC semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MOSFETs are used in half-bridge output circuits with rapid switching, then switching speed and power conversion efficiency are improved, but displacement currents cause gate-to-source voltage increases that may unintentionally turn on MOSFETs and create penetration currents
Solution Approach 1:
A gate short-circuit switching device is introduced as an intermediary component between the gate and source of each MOSFET. This device actively monitors and short-circuits the gate-to-source path when displacement currents occur, preventing the gate voltage from rising to dangerous levels that could cause unintended MOSFET turn-on and penetration currents, thus resolving the reliability issue while maintaining fast switching performance
2Reliability
If gate short-circuit switching devices are added to prevent gate-to-source voltage rise, then penetration current risk is reduced, but device complexity and module size increase
Solution Approach 1:
The gate short-circuit switching devices are merged with the existing MOSFET structure by mounting both devices on the same substrate. This integration approach allows the protective function to be added without significantly increasing module size, as the short-circuit switching devices share the same physical platform and electrical connections with the MOSFETs they protect
Solution Approach 2:
The invention uses SiC (silicon carbide) semiconductor devices for the gate short-circuit switching components, which have superior electrical and thermal properties compared to traditional silicon devices. This material parameter change enables smaller, more efficient components that provide the same protective function with reduced size and improved performance
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
Effectively prevents the rise in gate-to-source voltage, reducing the risk of penetration currents and minimizing the module's size by short-circuiting displacement currents and utilizing high-performance SiC semiconductor devices.
Implementation Method 1
a first gate short-circuit switching device connected between a gate and a source of the first power switching device, and a second gate short-circuit switching device connected between a gate and a source of the second power switching device
Implementation Method 2
utilizing high-performance SiC semiconductor devices
Data Source
AI summary
A power module (2) includes a first high-side main-circuit MOSFET (21) and a second low-side main-circuit MOSFET (22) connected in series thereto. The series circuit of the MOSFETs (21, 22) is connected in parallel to a power source (4). A first short-circuit MOSFET (25) is connected between the gate and the source of the first main-circuit MOSFET (21). A second short-circuit MOSFET (26) is connected between the gate and the source of the second main-circuit MOSFET (22).