Capacitive Current Measurement in Power Semiconductor Devices
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Solution Overview
Problem
Semiconductor devices, such as MOS-based power semiconductor devices, face challenges in withstanding overload currents without damage, as they are typically designed for nominal load conditions and may suffer damage from prolonged overload situations.
Innovation Solution
A semiconductor device with a control electrode and an electrically floating sensor electrode capacitively coupled to the load current path, allowing for capacitive current measurement and adaptive control to prevent damage during overload conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor device is designed for nominal load conditions, then the device operates efficiently under normal conditions, but the device cannot withstand prolonged overload currents without suffering damage
Solution Approach 1:
The patent implements preliminary action by measuring the load current before damage can occur and triggering protective measures in advance. The current measurement circuit continuously monitors the load current, and when an overload condition is detected, the control unit activates protective measures such as reducing the control signal to the semiconductor device or triggering a shutdown sequence, preventing damage before it happens.
Solution Approach 2:
The patent employs feedback by using the measured load current information to adjust the control of the semiconductor device. The control unit receives feedback from the current measurement circuit and modifies its control signals accordingly - reducing power dissipation during overload conditions or shutting down the device when current exceeds safe thresholds, thereby protecting the device while maintaining adaptability.
2Reliability
If a current measurement circuit is implemented to detect overload conditions, then the device can be protected from damage, but the device complexity increases
Solution Approach 1:
The patent uses an intermediary approach by introducing a floating sensor electrode that is capacitively coupled to the load current path without direct electrical connection. This intermediary measurement method allows current detection while maintaining electrical isolation, reducing the complexity of the measurement circuit compared to direct current sensing methods that would require additional isolation components and complex wiring.
Solution Approach 2:
The patent replaces traditional electrical current measurement methods with a capacitive coupling-based measurement system. Instead of using current shunts, Hall effect sensors, or other electrical measurement techniques that require direct electrical connections and additional components, the invention uses the capacitive effect to sense current through voltage changes on the floating electrode, simplifying the overall system 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
Enables the semiconductor device to safely manage overload currents by detecting and responding to excessive load currents, preventing damage and ensuring continuous operation.
Implementation Method 1
an electrically floating sensor electrode arranged adjacent to the control electrode, wherein the sensor electrode is electrically insulated from each of the semiconductor body and the control electrode and is capacitively coupled to the load current path
Data Source
AI summary
A semiconductor device includes a first load terminal, a second load terminal and a semiconductor body coupled to the first load terminal and the second load terminal. The semiconductor body is configured to conduct a load current along a load current path between the first load terminal and the second load terminal. The semiconductor device further includes a control electrode electrically insulated from the semiconductor body and configured to control a part of the load current path, and an electrically floating sensor electrode arranged adjacent to the control electrode. The sensor electrode is electrically insulated from each of the semiconductor body, and the control electrode and is capacitively coupled to the load current path.