EVSE Interchangeable Cords with Thermistor Voltage Detection
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Solution Overview
Problem
Electric vehicle supply equipment (EVSE) lacks the ability to efficiently switch between 120 VAC and 240 VAC charging standards, leading to prolonged charging times and potential damage from improper voltage configurations when users interchange power cords.
Innovation Solution
An EVSE assembly with interchangeable power supply cords conforming to NEMA 5-15 and 6-20 standards, featuring thermistors for temperature monitoring and a controller for automatic voltage detection and switching, ensuring safe and efficient charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hard-wired NEMA 5-15 power supply cord is used for 120 VAC charging, then the charging equipment is simple and reliable, but the charging time is prolonged (8-10 hours) and the equipment cannot adapt to 240 VAC standards
Solution Approach 1:
The power supply cord is segmented into two separate interchangeable cords: a NEMA 5-15 cord for 120 VAC operation and a NEMA 6-20 cord for 240 VAC operation. Each cord can be independently connected to the EVSE unit, allowing voltage standard adaptability without requiring a single complex integrated connector. The connector housing includes separate receptacles for each cord type, enabling users to switch between voltage standards by simply plugging in the appropriate cord.
2Productivity
If interchangeable power supply cords are provided to enable both 120 VAC and 240 VAC operation, then charging time is reduced by up to 50%, but the risk of improper cord configuration and potential damage increases
Solution Approach 1:
The EVSE unit incorporates a control system that provides feedback to detect which power supply cord is currently connected. The controller monitors the electrical characteristics of the connected cord and automatically configures the charging parameters based on the detected voltage standard (120 VAC or 240 VAC). This feedback mechanism prevents improper operation by ensuring the charging circuit is properly configured for the connected cord type, thereby maintaining reliability while enabling fast charging capability.
Solution Approach 2:
The system performs automatic self-configuration upon detecting the connected cord type. The control system automatically adjusts internal circuitry and charging parameters without requiring manual intervention from the user. This self-service approach eliminates the risk of user error in configuring the charging system, ensuring safe operation while enabling the productivity benefit of faster charging when 240 VAC is available.
3Adaptability or versatility
If a single EVSE unit must support both 120 VAC and 240 VAC standards, then the equipment becomes more versatile, but the complexity of voltage detection and automatic switching increases
Solution Approach 1:
The EVSE unit is pre-configured with separate receptacles and circuitry for both 120 VAC and 240 VAC connections before operation. The control system is pre-programmed with the electrical characteristics of both cord types. When a cord is connected, the system performs preliminary detection of the cord type and automatically switches to the appropriate voltage configuration. This preliminary preparation reduces the complexity of automatic switching during operation, as the system only needs to detect and select from pre-configured options rather than dynamically adapt.
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
Enables automatic switching between 120 VAC and 240 VAC operation, reducing charging time by up to 50% and providing enhanced safety through temperature and voltage monitoring, preventing damage from improper cord changes.
Implementation Method 1
The interchangeable power supply cord plugs each include a thermistor adapted to monitor plug temperatures
Data Source
AI summary
An electric vehicle supply equipment (EVSE) assembly for an electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV), often referred to as, optionally having one of at least two interchangeable power supply cords with plugs that conform to different technical standards, such as National Electrical Manufacturers Association (NEMA) 5-15P or 6-20P. The interchangeable power supply cord plugs each include a thermistor adapted to monitor plug temperatures. The electronic module is configured to disable charging until a proper resistance of the thermistor in the plug is detected. The electronic module is also configured to automatically switch between 120 volt and 240 volt operation based on which of the interchangeable power supply cords is connected to the electronic module.