SiC MOSFET Gate Driver Sensing for dv/dt and di/dt Control
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Solution Overview
Problem
Conventional gate drivers for high voltage and high power silicon carbide (SiC) MOSFETs face challenges in achieving the required control bandwidth under high current conditions, leading to issues such as voltage and current overshoots, electromagnetic interference, and inefficiencies due to the use of shunt resistors and other sensing components that are costly and inefficient.
Innovation Solution
The implementation of a gate driver circuitry that uses a capacitive divider to sense the drain voltage and a resistive divider to sense the current, allowing for dv/dt and di/dt control without the need for shunt resistors or current mirrors, enabling detection of overcurrent conditions and immediate protection without the need for external high voltage diodes or complex circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gate drivers use shunt resistors and current mirrors for sensing, then voltage and current can be detected, but the device complexity increases and cost increases
Solution Approach 1:
The patent extracts and eliminates the shunt resistors and current mirrors from the sensing circuit. Instead of using these complex components, the invention uses the intrinsic capacitance and resistance of the MOSFET itself along with simple RC circuits to achieve the same sensing function, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent makes the MOSFET serve multiple functions: it acts as both the power switching device and the sensing element. The intrinsic capacitance and resistance of the MOSFET are utilized for voltage and current sensing, eliminating the need for separate sensing components and reducing overall circuit complexity
2Measurement precision
If shunt resistors are used for current sensing, then current can be detected, but the efficiency decreases due to power loss
Solution Approach 1:
The patent removes the shunt resistors from the current sensing path. Instead of using external resistors that cause voltage drop and power loss, the invention uses the intrinsic resistance of the MOSFET and RC circuits to sense current, thereby eliminating the energy loss associated with traditional current sensing methods
Solution Approach 2:
The MOSFET's own intrinsic properties (capacitance and resistance) are used for sensing purposes. The device serves itself by utilizing its inherent characteristics rather than requiring external sensing components, which eliminates the energy loss that would otherwise be introduced by separate sensing elements
3Measurement precision
If conventional sensing components are used, then voltage and current can be sensed, but electromagnetic interference increases
Solution Approach 1:
The patent extracts and removes the problematic sensing components (shunt resistors and current mirrors) that generate electromagnetic interference. By using the MOSFET's intrinsic properties and simple RC circuits instead, the source of EMI is eliminated while sensing capability is maintained through alternative means
Solution Approach 2:
The patent replaces the physical sensing components (resistors and current mirrors) with an electrical field-based sensing method using the MOSFET's intrinsic capacitance and resistance. This substitution eliminates the need for additional conductive paths and components that would generate electromagnetic interference
4Reliability
If external high voltage diodes and complex circuitry are used for protection, then overcurrent protection can be provided, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the external high voltage diodes and complex protection circuitry. Instead, it uses simple RC circuits combined with the MOSFET's intrinsic properties to provide overcurrent protection, thereby maintaining reliability while significantly reducing the complexity of the protection circuit
Solution Approach 2:
The MOSFET and associated RC circuits serve multiple functions including switching, sensing, and protection. This multi-functionality eliminates the need for separate dedicated protection components, reducing overall circuit complexity while maintaining comprehensive protection capabilities
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 solution effectively senses and controls voltage and current in SiC MOSFETs, reducing electromagnetic interference, improving efficiency, and enabling faster response to overload conditions without the need for expensive or bulky sensing components, thus enhancing the reliability and performance of SiC-based power converters.
Implementation Method 1
A capacitive divider is coupled to the node, wherein the capacitive divider provides a first output
Implementation Method 2
A resistive divider is coupled to the node, wherein the resistive divider provides a second output
Data Source
AI summary
In circuitry for measuring a voltage at a node, a capacitive divider is coupled to the node, wherein the capacitive divider provides a first output. A resistive divider is coupled to the node, wherein the resistive divider provides a second output.