Semiconductor Switching Circuit for Limiting Starting Current Impulses
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Solution Overview
Problem
Existing methods for limiting starting current in intermediate voltage circuits, such as using NTC resistors or fixed resistors, are either costly or inefficient, leading to potential damage from high initial charging currents.
Innovation Solution
A circuit arrangement using a semiconductor structural element with a gate, a resistor, and a transistor to sequentially charge a storage capacitor with multiple charging current impulses, limiting the charging current through controlled switching states and voltage monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an NTC resistor is used to limit starting current, then the current after turning on is limited, but the resistance value drops very low when warm and the starting current impulse increases very greatly
Solution Approach 1:
The patent uses a dynamic switching mechanism where a semiconductor switch transitions between conducting and blocking states based on the charging status of the capacitor. This dynamic control allows the circuit to adapt its resistance characteristics in real-time, preventing the starting current impulse problem inherent in static NTC resistors whose resistance changes unpredictably with temperature.
Solution Approach 2:
The patent implements a feedback mechanism where the control circuit monitors the voltage across the capacitor and uses this information to control the switching element. This feedback ensures that the switch remains conducting only during the initial charging phase when current limitation is needed, and blocks current afterward, providing reliable and consistent current limitation regardless of temperature effects.
2Object-affected harmful factors
If a fixed resistor is connected in series to the intermediate circuit capacitor, then the starting current is limited, but an additional switching element is necessary which must also be regulated
Solution Approach 1:
The patent combines the functions of current limitation and switching control into a single integrated circuit arrangement. The semiconductor switch with its gate control mechanism serves both to limit the starting current and to automatically disconnect the series resistor after charging, eliminating the need for separate switching elements and reducing overall circuit complexity.
Solution Approach 2:
The control circuit serves multiple functions: it monitors the capacitor voltage, controls the timing of the semiconductor switch, and manages the disconnection of the series resistor. This multi-functional design reduces the number of separate components needed while maintaining effective current limitation and circuit protection.
3Reliability
If the drain source stretch of the semiconductor structural element is arranged in series with the storage capacitor, then the charging current is limited through controlled switching, but the circuit complexity increases compared to simple resistor solutions
Solution Approach 1:
The patent replaces mechanical or simple passive components (like thermal NTC resistors or mechanical switches) with a semiconductor-based electronic switching system. This substitution provides more precise and reliable control over the charging current while enabling automatic operation based on electrical parameters, ultimately reducing overall system complexity despite the advanced components used.
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
This solution effectively reduces starting current peaks, minimizing losses and ensuring reliable operation with fewer safety measures, thus protecting structural elements and reducing overall installation costs.
Implementation Method 1
a charging circuit is provided between a feed voltage source and the storage capacitor which comprises at least one semiconductor structural element with a gate, a resistor and a transistor
Implementation Method 2
the gate of the semiconductor structural element is connected or (depending on the switching state) can be connected to the mass potential via the drain source stretch of the transistor connected to this gate
Implementation Method 3
During the flowing of this charging current via the resistor a voltage drops on the latter which is applied via an (intermediate) tap on the transistor gate
Data Source
AI summary
The invention relates to a method and to a circuit arrangement for limiting the starting current for intermediate voltage circuits that have at least one storage capacitor.