EVSE Parallel Contactor Sequencing for In-Rush Current and Wear
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Solution Overview
Problem
Existing electric vehicle supply equipment (EVSE) systems do not effectively manage the sequential closure of contactors to minimize in-rush current and ensure even wear, leading to potential inefficiencies and reduced contactor lifespan.
Innovation Solution
The proposed system and method involve a controller that sequentially closes a pair of parallel contactors in the EVSE, with the last contactor to be closed based on a zero-voltage crossing of power, and the first contactor not closed based on a zero-voltage crossing, to manage in-rush current and distribute wear evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contactors are closed simultaneously in EVSE, then the connection is established quickly, but in-rush current increases and contactor wear becomes uneven
Solution Approach 1:
The patent divides the simultaneous closure action into sequential steps by closing one contactor first, then closing the second contactor after a predetermined time delay. This segmentation of the closure process reduces the peak in-rush current while maintaining acceptable connection speed.
Solution Approach 2:
The patent applies preliminary action by closing the first contactor before the second contactor, preparing the circuit in stages. This preliminary closure of one contactor allows the system to establish partial connectivity before completing the full connection, thereby controlling current surge.
2Ease of operation
If contactors are closed simultaneously in EVSE, then the system is simple to operate, but contactor wear becomes uneven reducing lifespan
Solution Approach 1:
The controller automatically implements preliminary action by sequencing the contactor closures, eliminating the need for manual coordination while ensuring even wear distribution. This automated sequencing maintains ease of operation while extending contactor lifespan.
Solution Approach 2:
The system incorporates feedback through timing mechanisms that monitor and control the closure sequence, ensuring that contactors are closed at optimally spaced intervals. This feedback-controlled timing distributes wear evenly across both contactors while maintaining automated operation.
3Object-affected harmful factors
If contactors are closed with sequential timing in EVSE, then in-rush current is reduced, but the control complexity increases
Solution Approach 1:
The patent employs periodic action through a predetermined time delay mechanism that automatically sequences the contactor closures at fixed intervals. This periodic timing approach reduces in-rush current while maintaining relatively simple control logic based on time-based sequencing rather than complex real-time monitoring.
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 approach reduces in-rush current and promotes even wear of the contactors, enhancing the efficiency and longevity of the EVSE system.
Implementation Method 1
a last of the pair to be closed is closed based on a zero-voltage crossing of power associated with the power source and a first of the pair to be closed is not closed based on a zero-voltage crossing of the power
Data Source
AI summary
Electric vehicle supply equipment may include a pair of parallel contactors that electrically connect a vehicle with a power source. It also includes a controller that closes one of the pair before the other of the pair based on a cumulative exposure to in-rush current of each of the pair.