Multi-Battery Pre-Charge Control for Inrush Current Limiting
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Solution Overview
Problem
Pre-charging techniques for inductive and capacitive loads in vehicles, such as heavy-duty trucks and buses, face challenges including high complexity, increased costs, and prolonged charging times due to the need for additional circuitry and control mechanisms, which can lead to voltage imbalances and potential damage from inrush currents.
Innovation Solution
A computer system with processing circuitry that controls multiple battery packs to provide pre-charge in a supportive mode, monitoring voltage differences between battery packs and the load to discontinue pre-charge if a battery pack's voltage is below the load voltage, thereby reducing the risk of uneven voltages and shortening pre-charge time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pre-charging circuitry and control mechanisms are used to limit inrush current, then the electrical system is protected from excessive currents, but the system complexity increases and additional components are required
Solution Approach 1:
The battery management system automatically monitors voltage differences between battery packs and the load, and autonomously controls the pre-charging process without requiring external intervention or complex additional control mechanisms. The system serves itself by detecting when pre-charging is complete and disconnecting the pre-charging circuitry automatically.
Solution Approach 2:
The existing battery management system is made multi-functional by adding voltage difference monitoring capabilities to its existing functions. The same control system that manages battery charging now also controls pre-charging operations, eliminating the need for separate dedicated pre-charging control circuitry.
2Reliability
If traditional pre-charging with gradual voltage application is used, then inrush current is limited, but the pre-charging time is prolonged
Solution Approach 1:
The system continuously monitors the voltage difference between the battery pack and the load during pre-charging. When the voltage difference falls below a threshold (indicating the load voltage is within 5% of the battery voltage), the system receives feedback that pre-charging is complete and automatically disconnects the pre-charging circuitry, preventing unnecessary time extension.
Solution Approach 2:
The pre-charging process is made dynamic by continuously adjusting the monitoring and control based on real-time voltage differences. The system transitions from a static fixed-time pre-charging approach to a dynamic adaptive approach that adjusts the pre-charging duration based on actual electrical conditions.
3Productivity
If multiple battery packs are used for pre-charging, then pre-charging capacity is increased, but voltage imbalances may occur between battery packs
Solution Approach 1:
The system applies different control strategies to different battery packs based on their individual voltage levels. Each battery pack's contribution to pre-charging is independently monitored and controlled, allowing the system to optimize the performance of each pack while maintaining overall system stability.
Solution Approach 2:
The system monitors voltage differences between multiple battery packs and the load, ensuring that all battery packs operate at compatible voltage levels during pre-charging. By detecting when voltage differences exceed thresholds, the system prevents significant voltage imbalances from developing between parallel battery packs.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A computer system (100) is presented. The computer system (100) comprises processing circuitry (110) configured to control a first battery pack (210a) and a second battery pack (210b) to provide pre-charge to a load (29). The processing circuitry (110) is further configured to configure the first battery pack (210b) to provide pre-charge in a supporting pre-charge mode, and during pre-charge in the supporting pre-charge mode, monitor a first voltage difference indicator indicating a difference between a load voltage (314) and a first battery pack voltage (312a). The processing circuitry (110) is further configured to, responsive to the first voltage difference indicator indicating that first battery pack voltage (312a) is at or below the load voltage (314), control the first battery pack (210a) to discontinue pre-charge of the load (29).