Overvoltage Protection Circuit With Emergency Load Operation
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Solution Overview
Problem
Existing overvoltage protection systems struggle to effectively manage both transient and temporary overvoltages, particularly in low-voltage consumer systems, as transient overvoltages can cause significant strain and temporary overvoltages require emergency operation capabilities.
Innovation Solution
A circuit arrangement using controlled semiconductor switches in series and transverse branches with capacitive and inductive components, along with a microcontroller for detection and control, ensures emergency operation with constant power by employing a combination of surge arresters, mechanical switches, and capacitive voltage dividers to handle both transient and temporary overvoltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If arresters are used to limit temporary overvoltages, then some protection is provided, but the arresters experience very high strain due to the long duration of temporary overvoltages
Solution Approach 1:
The patent replaces traditional mechanical arresters with controlled semiconductor switches in the series branch. The first semiconductor switch, controlled by the control unit, can rapidly open to interrupt temporary overvoltages, eliminating the high strain that would otherwise be placed on mechanical arresters and significantly improving their durability.
2Reliability
If a mechanical switch is used in the series branch, then protection is provided, but the mechanical switch has inertia that delays response to transient overvoltages
Solution Approach 1:
The patent replaces the mechanical switch in the series branch with a first semiconductor switch that can be rapidly activated and deactivated by the control unit. This substitution eliminates the mechanical inertia that would otherwise delay the response to transient overvoltages, enabling microsecond-level response times.
3Speed
If semiconductor switches are used for rapid switching, then response speed to transient overvoltages is improved, but power loss increases during operation
Solution Approach 1:
The control unit implements periodic monitoring of the input voltage and activates the first semiconductor switch only when temporary overvoltage conditions are detected. During normal operation, the switch remains off, minimizing power loss. This on-demand activation strategy maintains rapid response capability while significantly reducing energy consumption during steady-state operation.
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 comprehensive protection against both transient and temporary overvoltages, enabling continuous operation of safety-relevant loads with reduced power loss and extended switch lifespan by leveraging capacitive voltage dividers and inductive decoupling for quick response to transient events.
Implementation Method 1
a series capacitance (C seri es), in particular a DC-blocking capacitance
Implementation Method 2
a parallel connection of a second surge arrester, in particular a varistor and a transverse capacitance (C quer)
Implementation Method 3
a series inductance (L), in particular a decoupling inductance
Implementation Method 4
a parallel connection of a second surge arrester, in particular a varistor
Data Source
AI summary
The invention relates to a circuit arrangement for combined protection of a load from temporary and transient overvoltages with emergency operation of the load in the presence of a temporary overvoltage and with integrated follow current limitation, wherein a first surge arrester, in particular a spark gap or a varistor, is provided between network-side input terminals and a second surge arrester, in particular a varistor, is provided between load-side output terminals for follow current limitation. According to the invention, at least one controlled semiconductor switch is provided in each case in the series branch between the input terminal and the output terminal and in the output-side parallel branch, wherein a mechanical switch and a series capacitance are connected in parallel with the semiconductor switch in the series branch. Furthermore, the semiconductor switch in the parallel branch is part of a series circuit comprising a parallel circuit comprising a second surge arrester and a parallel capacitance. A series inductance is provided in the series branch between the input terminal and the parallel circuit comprising the series capacitance, the controlled semiconductor switch and the mechanical switch. A microcontroller for controlling the semiconductor switches is also present, wherein the microcontroller is connected to a current detector in the series branch.