EVSE Virtual Branch Current Control Without Service Upgrades
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Solution Overview
Problem
Existing methods require expensive service entrance upgrades to install Electric Vehicle Supply Equipment (EVSE) in homes with insufficient service sizes, as conventional systems fail to account for existing loads and adhere to National Electrical Code (NEC) requirements.
Innovation Solution
A virtual branch circuit system with a current sensor and control module that senses total current of non-EVSE loads, allowing the EVSE to operate within a maximum branch current threshold without upgrading the service size, ensuring NEC compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If service entrance upgrade is performed to install EVSE, then EVSE installation is enabled, but installation cost increases significantly
Solution Approach 1:
The system dynamically adjusts the EVSE current demand based on real-time monitoring of existing branch circuit loads. The control module continuously senses the total current drawn by non-EVSE loads and dynamically calculates the remaining available current capacity, allowing the EVSE to operate at variable power levels rather than requiring a fixed high-capacity service upgrade.
Solution Approach 2:
The system implements a feedback loop where the control module continuously monitors the total current on branch circuits through current sensors, compares it against the maximum available capacity, and adjusts the EVSE current demand accordingly. This closed-loop control ensures the EVSE operates within available capacity without requiring service upgrades.
2Ease of manufacture
If EVSE is installed without service upgrade, then installation cost is reduced, but NEC compliance becomes problematic
Solution Approach 1:
The control module continuously monitors branch circuit current consumption and uses this feedback to dynamically adjust EVSE current demand, ensuring the total load never exceeds the branch circuit breaker rating. This real-time compliance monitoring and adjustment mechanism ensures NEC requirements are met without requiring service upgrades.
Solution Approach 2:
The system transitions from static NEC compliance calculations to dynamic compliance verification by continuously monitoring actual load conditions and adjusting EVSE current demand in real-time, allowing compliance with NEC requirements while operating within existing service capacity.
3Productivity
If maximum current demand is allocated to EVSE, then charging speed is maximized, but existing loads may experience power interruption
Solution Approach 1:
The system dynamically balances power allocation between EVSE and existing loads by continuously monitoring total branch circuit current and adjusting EVSE current demand in real-time. This dynamic load management ensures that the sum of EVSE and existing load currents never exceeds the branch circuit breaker rating, preventing power interruptions to existing appliances while maximizing charging speed within available capacity.
Solution Approach 2:
The system allows the EVSE to draw up to the maximum available current capacity calculated as (branch circuit rating - existing load current), which may vary from moment to moment. This partial action approach ensures the EVSE receives as much power as available without exceeding safe operating limits, optimizing charging speed while maintaining reliability.
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 the installation of EVSE without service upgrades by dynamically managing current demand, maintaining branch current within limits and adhering to NEC standards, thus reducing installation costs.
Implementation Method 1
a current sensor disposed in operative communication with circuit wires of a plurality of circuits of a virtual branch
Data Source
AI summary
A virtual branch circuit system for an electric vehicle supply equipment (EVSE) can include a current sensor disposed in operative communication with circuit wires of a plurality of circuits of a virtual branch. The current sensor can be disposed between a plurality of circuit breakers and a plurality of respective loads. At least one of the plurality of loads is not an EVSE. The current sensor can be configured to sense a virtual branch total current comprising total current of all non-EVSE loads on the virtual branch. The system can include a control module operatively connected to the EVSE to control a maximum EVSE current based on the virtual branch total current to maintain the virtual branch total current at or under a maximum branch current threshold.