Self-Powered Electrical Protective Circuit for Overvoltage
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Solution Overview
Problem
Existing electrical protective circuits for overvoltage and reverse polarity protection suffer from high losses and require external energy sources, leading to inefficiencies and limitations in current or voltage supply.
Innovation Solution
An electrical protective circuit with a controllable switch, sensor device, and energy supply device that converts voltage drops into supply voltage, allowing for efficient protection without external energy sources, using components like FET transistors and converters to manage voltage and polarity fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thyristor is used as the short-circuit switch in a crowbar circuit, then the protective function is ensured, but high losses occur across the thyristor and fuse limitations restrict the connected power source
Solution Approach 1:
The patent changes the operating parameters by using a FET instead of a thyristor, allowing for lower on-resistance and reduced power losses while maintaining the protective function. The FET's voltage-controlled operation enables more efficient current management during fault conditions.
Solution Approach 2:
The patent replaces the mechanical/fixed operation of a thyristor with an electronically controlled FET system, enabling more flexible and efficient control of the switching path through voltage signals from the sensor device.
2Reliability
If an external energy source is used to control the FET short-circuit switch, then the protective function is ensured, but additional costs and failure risks are introduced
Solution Approach 1:
The patent implements self-service by having the sensor device generate the control voltage directly from the input voltage to drive the FET gate. This eliminates the need for separate external energy sources while ensuring the protective circuit remains fully functional and autonomous.
Solution Approach 2:
The sensor device serves multiple functions: it detects incorrect main input voltages, generates control signals for the FET, and provides the necessary gate drive voltage, thereby eliminating the need for dedicated external energy sources.
3Device complexity
If the control voltage of the FET is provided by the input voltage of the crowbar circuit, then external energy sources are eliminated, but the protective function may not be ensured in the case of reverse polarity
Solution Approach 1:
The patent uses the input voltage in its normal configuration without reversal, allowing the sensor device to correctly detect reverse polarity conditions and generate appropriate control signals to close the switching path, thereby protecting against reverse polarity while maintaining simplicity.
4Reliability
If switches are used in overvoltage protectors, then overvoltage protection is provided, but high losses occur during regular operation and switches can only be used for short periods
Solution Approach 1:
The patent employs periodic action by keeping the FET in a high-impedance off state during normal operation and only activating it periodically when overvoltage or reverse polarity conditions are detected, thereby minimizing losses during regular operation while maintaining protection capability.
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 energy-efficient protection against overvoltages and reverse polarity, reducing energy consumption and eliminating the need for external energy sources, while ensuring reliable operation across varying voltage conditions.
Implementation Method 1
an energy supply device, which is connected in parallel to the switching path and is designed to convert a voltage drop across the closed controllable switch into a supply voltage
Data Source
AI summary
The present disclosure relates to an electrical protective circuit, comprising: an input terminal to which a main input voltage can be applied; a switching path arranged in parallel with the input terminal, wherein a controllable switch is configured to close the switching path; a sensor device connected to the input terminal and configured to detect an incorrect main input voltage present at the input terminal, wherein the sensor device is further configured to transmit a control signal to the controllable switch to close the switching path when an incorrect main input voltage is detected; and an energy supply device connected in parallel with the switching path and configured to convert a voltage drop across the closed controllable switch into a supply voltage and to apply the supply voltage to the sensor device.