Power Switch Protection Circuit Using Single-Terminal Fault Sensing
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Solution Overview
Problem
Switched mode power converters face challenges in protecting power switches from overvoltage and overcurrent conditions, especially as operational voltages increase, leading to complex and costly protection circuitry that struggles to detect and respond effectively across a wide range of parameters.
Innovation Solution
A switch controller with a switch fault detector that monitors voltage and current signals at a single sense terminal to detect overcurrent, short circuits, and overvoltage conditions, actively clamping voltages and turning off the power switch to prevent damage, using a combination of resistive and capacitive components to sense and respond to fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional protection circuitry is used for power switches, then protection against overvoltage and overcurrent conditions is provided, but the circuitry becomes complex and costly
Solution Approach 1:
The patent combines overvoltage detection and overcurrent detection circuits into a single integrated protection system that shares common components such as the sense terminal, resistive divider network, and control logic. This merging approach maintains comprehensive protection capabilities while reducing overall circuit complexity and component count.
Solution Approach 2:
The protection circuit is designed with multi-functional elements that can detect and respond to multiple fault conditions (overvoltage, overcurrent, short circuits) using a unified architecture. The single sense terminal and shared resistive divider serve multiple detection purposes, eliminating the need for separate dedicated circuits for each protection function.
2Reliability
If traditional protection circuitry is used for power switches, then protection against overvoltage and overcurrent conditions is provided, but the cost increases
Solution Approach 1:
By merging multiple protection functions into a single integrated circuit with shared components (sense terminal, resistive dividers, control logic), the bill of materials is reduced and manufacturing complexity is lowered, directly decreasing production costs while maintaining comprehensive protection.
Solution Approach 2:
The universal protection circuit design uses multi-functional components that perform multiple protection tasks, reducing the total number of parts required and simplifying assembly processes, thereby lowering manufacturing costs compared to traditional multi-circuit approaches.
3Measurement precision
If protection circuitry is designed for a narrow range of parameters, then detection and response is effective, but the circuitry cannot manage a wide range of operational parameters
Solution Approach 1:
The protection circuit incorporates dynamic threshold adjustment mechanisms where the detection thresholds for overvoltage and overcurrent protection can adapt to different operational conditions. The control logic dynamically responds to varying load conditions and switching frequencies, maintaining precise detection across a wide range of parameters rather than using fixed thresholds.
Solution Approach 2:
The circuit design allows detection parameters such as voltage thresholds and current thresholds to be adjusted based on operational conditions. The resistive divider ratios and sensing parameters can be optimized for different voltage levels and current ranges, enabling the same circuit to maintain precise detection across diverse operational parameters through parameter adaptation.
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
The solution provides robust protection against overvoltage and overcurrent conditions, enhancing the reliability and efficiency of power converters by simplifying the protection circuitry and reducing costs, while effectively managing a wide range of operational parameters.
Implementation Method 1
a capacitance coupled between the sense terminal and a reference potential. The capacitance slows down a rate of increase of a voltage at the sense terminal
Implementation Method 2
a resistance having one end coupled to the sense terminal and the other end coupled to the first terminal. The resistance discharges the capacitance
Data Source
AI summary
Driver circuitry for driving a power semiconductor switch having a control input and main terminals is described. The driver circuitry includes control terminal driver circuitry coupled to the control input and configured to provide a drive signal, a sense terminal coupled to the main terminal, a current mirror coupled to the sense terminal to mirror a current input into the sense terminal during turn-off, a first current comparator configured to compare a current signal received from the current mirror to a first current threshold and output a first signal representative of the comparison, and a second comparator configured to compare a signal received from the sense terminal to a turn-on threshold and output a second signal representative of the comparison. The turn-on threshold represents a highest voltage of the main terminal during turn-on. The first current threshold represents a highest voltage of the main terminal during turn-off.