Load Pre-Charge Circuit Using Parallel PTC Resistor Arrays
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Solution Overview
Problem
Existing pre-charge solutions for machines with high load capacitances result in increased space usage and cost due to the exponential increase in the number of positive thermal coefficient (PTC) resistors required, which can lead to machine damage from in-rush power and current.
Innovation Solution
A pre-charge circuit that includes a power resistor in series with arrays of PTC resistors arranged in parallel, reducing the total number of resistors needed while providing efficient pre-charging for high voltage and high capacitance machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTC resistors are used for pre-charging in machines with high load capacitances, then machine load damage from in-rush current is prevented, but space usage and cost increase exponentially
Solution Approach 1:
The pre-charge circuit is segmented into two functional parts: a power resistor for initial current limiting and multiple PTC resistors arranged in parallel arrays for sustained pre-charging. This segmentation allows each component to be optimized for its specific function, reducing the total number of PTC resistors needed while maintaining protection reliability
Solution Approach 2:
The patent combines power resistors and PTC resistors into a single integrated pre-charge circuit that operates in stages. The power resistor handles the initial high current phase, then transitions to the PTC resistor arrays for continued current limiting as capacitance charges, merging the functions of multiple components into a coordinated system
2Reliability
If multiple PTC resistors are used to handle high load capacitances, then pre-charging effectiveness is improved, but space usage increases
Solution Approach 1:
The patent transitions from a single-series PTC resistor configuration to a multi-dimensional parallel array structure. By arranging PTC resistors in parallel arrays with specific connectivity patterns, the circuit achieves effective pre-charging across multiple capacitance levels while occupying less physical space than equivalent single-series configurations
3Reliability
If the number of PTC resistors is increased to handle high capacitance loads, then pre-charging capability is improved, but cost increases
Solution Approach 1:
The pre-charge circuit operates dynamically, transitioning between different resistor configurations as the charging process progresses. The power resistor is initially active, then the circuit dynamically engages the PTC resistor arrays in parallel as capacitance levels increase, allowing the system to adapt its resistance profile to match changing electrical conditions rather than requiring fixed high numbers of PTC resistors
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 achieves space savings and increased safety by preventing machine damage from in-rush current, while maintaining the technical benefits of PTC resistors, particularly for high voltage/high capacitance machines.
Implementation Method 1
a plurality of arrays of positive temperature control (PTC) resistors, the plurality of arrays of PTCs resistors electrically coupled in parallel with one another
Implementation Method 2
The pre-charge circuit includes a power resistor electrically coupled in series with the one or more machine batteries
Data Source
AI summary
Systems and methods for load pre-charging may include a machine having one or more machine batteries, one or more machine loads, and a pre-charge circuit intermediary to the one or more machine batteries and the one or more machine loads. The pre-charge circuit may include a power resistor electrically coupled in series with the one or more machine batteries. The pre-charge circuit may include a plurality of arrays of positive temperature control (PTC) resistors, the plurality of arrays of PTCs resistors electrically coupled in parallel with one another, and in series between the power resistor and the one or more machine loads.