PCM-Embedded Precharge Resistor Assembly for Inrush Heat Control
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Solution Overview
Problem
Existing resistor circuits in electric machines fail to effectively manage and dissipate excess inrush current, leading to potential component damage and reduced lifespan due to thermal energy accumulation.
Innovation Solution
A resistor assembly embedded in a phase change material (PCM) container that absorbs thermal energy by changing states to dissipate heat away from resistors, allowing them to remain immersed for additional inrush current instances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor circuit is used to control inrush current, then inrush current is limited, but thermal energy accumulates causing component damage and reduced lifespan
Solution Approach 1:
The patent applies phase change material (PCM) that undergoes phase transition from solid to liquid state when absorbing thermal energy from the resistor. This phase transition occurs at a specific temperature range, allowing the PCM to absorb large amounts of heat without significant temperature increase, thereby protecting the resistor from thermal damage and extending component lifespan.
Solution Approach 2:
The PCM acts as an intermediary thermal management component between the resistor and the environment. It mediates the heat transfer process by first absorbing thermal energy directly from the resistor through phase change, then gradually dissipating the stored thermal energy to the surrounding environment, preventing direct thermal damage to the resistor.
2Temperature
If thermal energy is dissipated continuously, then component temperature is controlled, but the system requires larger heat sink structures and increased complexity
Solution Approach 1:
The PCM utilizes its phase transition properties to provide passive thermal management. During the phase change process, the material absorbs thermal energy without significant temperature rise, effectively controlling the resistor temperature without requiring complex active cooling systems or large heat sinks. The phase change process itself serves as the primary heat dissipation mechanism.
Solution Approach 2:
The thermal management system operates autonomously without external control. The PCM automatically absorbs thermal energy when the resistor temperature rises and gradually releases it when the temperature decreases, providing self-regulating temperature control. This eliminates the need for complex control systems, fans, or external cooling infrastructure.
3Reliability
If multiple resistors are used to handle repeated inrush current instances, then current control is maintained, but the device complexity and space requirements increase
Solution Approach 1:
The PCM enables a single resistor to handle repeated inrush current events by absorbing the thermal energy from each event during its liquid phase. The phase change material continuously cycles between absorbing heat during inrush events and dissipating heat to the environment, allowing the same resistor to be reused indefinitely without thermal damage, eliminating the need for multiple resistors or complex switching arrangements.
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
Effectively manages inrush current thermal energy, preventing component overheating and damage by repeatedly absorbing and dissipating heat, reducing the need for multiple resistors and extending component lifespan.
Implementation Method 1
The PCM absorbs thermal energy associated with the one or more heat impulses by changing a state of the PCM from a first state to a second state to dissipate the thermal energy away from the at least one resistor
Implementation Method 2
The resistor assembly includes at least one resistor configured to control one or more instances of inrush current from a power source of the power system to a capacitor of the power system and generate one or more heat impulses corresponding to the one or more instances of inrush current
Data Source
AI summary
A resistor assembly for a precharge circuit of a power system is described. The resistor assembly includes at least one resistor configured to control one or more instances of inrush current from a power source of the power system to a capacitor of the power system and generate one or more heat impulses corresponding to the one or more instances of inrush current. The resistor assembly includes a container filled with a phase change material (PCM) and the resistor embedded in the PCM. The PCM absorbs thermal energy associated with the one or more heat impulses by changing a state of the PCM from a first state to a second state. When the state of the PCM changes to the second state, the resistor remains embedded or immersed in the PCM to receive additional thermal energy corresponding to additional instances of inrush current.