Gate Driver Voltage Sensing for SiC MOSFET dv/dt and di/dt Control
Find Innovative SolutionsGenerate Solutions
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 proposed solution involves 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 additional pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gate drivers use shunt resistors and current mirrors for sensing, then current measurement is achieved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the current sensing function from traditional shunt resistors and current mirrors, replacing them with a capacitive divider circuit that measures current indirectly through voltage division. This eliminates the need for complex sensing components while maintaining measurement capability.
Solution Approach 2:
The patent replaces the electrical sensing mechanism (shunt resistors and current mirrors) with a capacitive voltage division mechanism. The capacitive divider uses voltage division principles to derive current information without direct current path interruption, substituting the traditional electrical sensing approach.
2Measurement precision
If shunt resistors are used for current sensing, then current detection is enabled, but power loss and efficiency decrease
Solution Approach 1:
The patent removes shunt resistors from the current sensing path, eliminating the power loss associated with resistive sensing. The capacitive divider senses current through voltage division without creating a resistive path that dissipates power.
Solution Approach 2:
The patent substitutes resistive current sensing with capacitive voltage division, replacing the power-consuming shunt resistor mechanism with a lossless capacitive sensing approach that derives current information without direct current flow through sensing elements.
3Measurement precision
If conventional sensing components are used, then voltage and current measurement is achieved, but electromagnetic interference increases
Solution Approach 1:
The patent extracts the sensing function from traditional resistive components that generate electromagnetic interference and implements it through a capacitive divider. The capacitive sensing approach eliminates the resistive elements that are primary sources of EMI in conventional current sensing circuits.
Solution Approach 2:
The patent replaces the electromagnetic sensing mechanism based on resistance with a capacitive voltage division mechanism. This substitution eliminates the resistive heating and associated electromagnetic radiation, providing a cleaner sensing solution with reduced EMI.
4Reliability
If high voltage diodes and additional pins are used for protection, then overcurrent protection is achieved, but device complexity and cost increase
Solution Approach 1:
The patent makes the capacitive divider circuit multi-functional, using it for both normal voltage sensing and overcurrent protection detection. The same capacitive division network provides protection functionality without requiring separate high voltage diodes or additional protection circuitry, reducing overall device complexity.
Solution Approach 2:
The patent merges the voltage sensing and overcurrent protection functions into a single capacitive divider circuit. By combining these functions, the patent eliminates the need for separate protection components such as high voltage diodes and additional pins, simplifying the overall device architecture.
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 approach effectively measures and controls voltage and current across transistor nodes, reducing electromagnetic interference and improving efficiency by allowing for immediate protection against overcurrent conditions without the need for costly sensing components, thus enhancing the performance and reliability of SiC MOSFET drivers.
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.