Precharging Circuit for Intermediate Circuits with Interference Suppression
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Solution Overview
Problem
Existing circuits for precharging intermediate circuits in electrical systems often result in impermissibly high charging currents if not properly precharged, and lack effective methods for insulation fault detection and localization.
Innovation Solution
A circuit with controllable energy sources connected in series between the positive and negative branches of an intermediate circuit, including an interference suppression unit and a control device to generate output signal patterns for precharging and fault detection, utilizing a measuring device to measure voltages and currents, and alternately activating energy sources to generate output voltage test patterns for insulation fault localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the high-voltage battery is connected directly to the intermediate circuit without precharging, then the electrical system can be quickly powered up, but an impermissibly high charging current flows causing safety issues and component stress
Solution Approach 1:
The patent applies preliminary action by introducing a precharging circuit that charges the intermediate circuit capacitor before the main battery connection is established. This preliminary charging action raises the intermediate circuit voltage to near-battery voltage levels, ensuring that when the main connection occurs, only a minimal current surge is required, thus preventing impermissible high charging currents while maintaining quick system startup.
2Reliability
If traditional precharging circuits are used without interference suppression, then the precharging function is achieved, but conducted and radiated interference affects system reliability and insulation monitoring accuracy
Solution Approach 1:
The patent applies the intermediary principle by introducing an interference suppression unit as a mediator between the precharging circuit and the rest of the electrical system. This unit, containing filtering components and suppression elements, actively reduces conducted and radiated interference generated during precharging operations, thereby protecting the system from electromagnetic disturbances while maintaining precharging reliability.
3Device complexity
If insulation monitoring is not integrated into the precharging circuit, then the precharging circuit remains simple, but insulation faults cannot be detected or localized
Solution Approach 1:
The patent applies universality by designing the precharging circuit to perform multiple functions: precharging the intermediate circuit capacitor, suppressing interference, detecting insulation faults, and localizing fault positions. By integrating insulation monitoring capabilities directly into the precharging circuit, the system achieves comprehensive safety monitoring without requiring separate dedicated monitoring equipment, thus balancing complexity with enhanced reliability.
4Device complexity
If only single energy source precharging is used, then the circuit is simpler, but the system lacks redundancy and cannot tolerate energy source failures
Solution Approach 1:
The patent applies local quality by implementing a dual energy source configuration where each energy source can independently perform the precharging function. This redundancy ensures that if one energy source fails, the other can still complete the precharging operation, thereby enhancing system reliability without requiring complex coordination between multiple sources.
Data Source
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AI summary
The invention relates to a circuit (1) for pre-charging an intermediate circuit (50). The intermediate circuit (50) has a positive branch (2) and a negative branch (3), and the circuit (1) for pre-charging an intermediate circuit (50) has the following: - a first controllable energy source (4), - a second controllable energy source (5), said first control energy source (4) and second controllable energy source (5) being looped in series between the positive branch (2) and the negative branch (3) on the output side, - a suppression unit (26), said suppression unit (26) being looped between a connection node (N1) of the output of the first controllable energy source (4) and the output of the second controllable energy source (5) and a reference potential, and - a controller (30), wherein - the controller is connected to the first energy source (4) and the second energy source (5) for signaling purposes and - is designed to actuate the first energy source (4) and the second energy source (5) in order to generate an output signal pattern (Va, Vb) in order to pre-charge the intermediate circuit (50).