Series MOSFET-IGBT Power Line Layout for Overcurrent Suppression
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Solution Overview
Problem
Existing semiconductor devices with integrated MOSFETs to protect IGBTs from overcurrent fail to suppress current effectively, leading to increased IGBT and device size due to the need for high breakdown withstand.
Innovation Solution
Connecting MOSFETs in series with IGBTs on the power source line, allowing current suppression via ON resistance, eliminating the need for large-current-resistant IGBTs, and ensuring the MOSFETs are always in an ON state to prevent sudden overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MOSFET is connected between drive circuit and IGBT to detect ON voltage and block overcurrent, then high voltage protection is improved, but current suppression capability deteriorates
Solution Approach 1:
The patent introduces a current suppression circuit as an intermediary component between the MOSFET and the IGBT. This mediator circuit actively detects overcurrent conditions and responds by controlling the MOSFET gate, thereby suppressing harmful current while preserving the MOSFET's primary function of high voltage protection. The mediator circuit resolves the contradiction by adding a control layer that enables current suppression without compromising voltage blocking capability.
2Object-generated harmful factors
If IGBT is designed with high breakdown withstand to resist overcurrent, then current resistance is improved, but device size increases
Solution Approach 1:
The current suppression circuit acts as a mediator that protects the IGBT from overcurrent without requiring the IGBT itself to be oversized. The circuit detects overcurrent conditions and activates the MOSFET to block current flow, thereby protecting the IGBT while allowing it to maintain a compact, optimized design for its primary switching function.
Solution Approach 2:
Instead of designing the IGBT to withstand excessive current throughout its operation, the patent applies partial protection only when needed. The current suppression circuit activates the MOSFET selectively during overcurrent events, allowing the IGBT to operate at full capacity during normal conditions while receiving protective intervention only when harmful current levels are detected.
3Object-generated harmful factors
If MOSFET is added to suppress current in power source line, then overcurrent protection is improved, but device complexity increases
Solution Approach 1:
The patent merges the current suppression function with the existing MOSFET that is already present for voltage protection purposes. By utilizing the same MOSFET component for dual functions (voltage blocking and current suppression), the design avoids adding separate protection components, thereby reducing overall circuit complexity while achieving comprehensive protection.
Solution Approach 2:
The MOSFET is designed to serve multiple functions: it acts as a voltage blocking device for high voltage protection and simultaneously serves as a current suppression element when activated by the current suppression circuit. This multi-functionality eliminates the need for separate dedicated components, simplifying the overall device architecture while providing robust overcurrent protection.
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 configuration increases the degree of freedom in IGBT selection, enabling downsizing of the semiconductor device while effectively managing current flow during short circuits and overcurrents.
Implementation Method 1
current flowing in a power source line is suppressed by ON resistance of the MOSFET
Data Source
AI summary
A technique disclosed in the specification of the present application is a technique for increasing a degree of freedom of an IGBT in a device, and as a result, achieving downsizing of the device. A semiconductor device relating to a technique disclosed in the specification of the present application includes a plurality of IGBTs connected in series on a power source line in which bus current flows and a MOSFET connected to the plurality of IGBTs in series. The bus current flows via a drain terminal and a source terminal of the MOSFET.