Overvoltage Protection Circuit Using Voltage Divider Scaling
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Solution Overview
Problem
Existing overvoltage protection circuits for power semiconductor switches have high temperature dependency and aging tolerance, leading to inefficiencies in responding to short overvoltage peaks and requiring large safety margins, which can result in damage to the switches.
Innovation Solution
A voltage divider is used to reduce the voltage across power semiconductor switches, allowing for the use of low-voltage overvoltage detectors like Zener or suppressor diodes with improved operating parameters, reducing temperature dependency and aging, and enabling better response behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage overvoltage detectors are used directly across the power semiconductor switch, then overvoltage protection can be provided, but the temperature dependency and aging tolerance increase
Solution Approach 1:
The voltage monitoring function is segmented into two parts: a voltage divider that scales down the high voltage to a lower level, and a low-voltage overvoltage detector that monitors the scaled signal. This segmentation allows the detector to operate in a more favorable voltage range with reduced temperature dependency and improved aging tolerance.
Solution Approach 2:
The voltage divider acts as an intermediary between the high-voltage power semiconductor switch and the low-voltage overvoltage detector. It transforms the high-voltage signal into a proportional low-voltage signal that the detector can monitor with improved thermal and aging characteristics.
2Reliability
If high-voltage overvoltage detectors are used directly, then protection coverage is achieved, but the tolerance to aging increases
Solution Approach 1:
The protection system is segmented into a voltage divider stage and a detector stage, allowing the detector to operate at lower voltages where aging effects are reduced, thereby improving long-term reliability while maintaining full protection coverage.
Solution Approach 2:
The voltage level parameter is changed from high voltage (direct monitoring) to low voltage (scaled monitoring) through the voltage divider. This parameter transformation reduces the stress on the detector component, lowering aging tolerance requirements and extending component lifespan.
3Reliability
If conventional overvoltage protection is used, then basic protection is provided, but the response behavior to short overvoltage peaks is insufficient due to low dynamics
Solution Approach 1:
The voltage level parameter is transformed from high to low through the voltage divider, enabling the use of detectors with optimized operating parameters including faster response times. Low-voltage detectors can react more quickly to overvoltage events, improving the system's ability to respond to short peaks.
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 reliable overvoltage protection with reduced temperature fluctuations and aging, allowing for more precise adaptation to the breakdown voltage of the semiconductor switch, thus preventing damage and improving overall system stability.
Implementation Method 1
a voltage present across a power semiconductor switch is converted by means of a voltage divider to a low voltage signal corresponding to the voltage present at the power semiconductor switch
Implementation Method 2
an overvoltage detector can be used in a significantly lower voltage range by lowering the voltage using a voltage divider... an overvoltage detector is preferably a semiconductor diode which becomes conductive when a predetermined voltage is exceeded
Data Source
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AI summary
The invention relates to an overvoltage protection circuit (5) and a method for protecting a power semiconductor (31, 32) from over-voltages. For this purpose, a voltage applied across a power semiconductor switch is first converted to a lower voltage signal corresponding to the voltage applied to the power semiconductor switch by means of a resistance voltage divider. The reduced voltage signal is then evaluated by means of an overvoltage detector, such as a Zener or suppression diode, and the power semiconductor switch to be protected is activated if the response voltage of said diode is exceeded. By lowering the voltage level by means of a voltage divider, a Zener or suppression diode having a lower voltage level can be used for monitoring the overvolatage, said Zener or suppression diode having improved operating properties in comparison with corresponding diodes having a higher voltage level.