EV Charger Dry Contact Load Alignment Using a CT Clamp
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Solution Overview
Problem
Existing solutions for aligning electric vehicle (EV) charging load with whole circuit consumption require additional expensive meters or digital communication, which may not be feasible in all locations.
Innovation Solution
A dry contact-based system that uses a current transformer (CT) clamp installed on an external electrical circuit to measure current and generate a calibrated signal, allowing the EVSE to automatically adjust the charging load by large steps down and adaptable steps up, without the need for additional accurate current meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional accurate current meters are installed to measure circuit current for EV charging alignment, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a current transformer (CT) clamp as an intermediary device that clamps around the circuit breaker cable to indirectly measure circuit current. This CT clamp converts current into a proportional voltage signal that can be read by the EVSE's existing dry contact input, eliminating the need for additional accurate current meters while maintaining measurement capability
Solution Approach 2:
The patent replaces the need for complex electronic current measurement systems with a simpler electromagnetic induction-based CT clamp. The CT clamp uses magnetic field induction to transform circuit current into a measurable voltage signal, substituting complex electronic measurement with a more straightforward electromagnetic sensing approach
2Measurement precision
If additional meters or digital communication infrastructure are added to enable EV charging load alignment, then alignment accuracy is improved, but ease of operation and installation ease deteriorate
Solution Approach 1:
The CT clamp serves as a non-intrusive intermediary that clamps around existing cables without requiring circuit disconnection or installation inside electrical panels. This allows the system to tap into existing circuit breaker infrastructure and dry contact inputs, eliminating the need for complex digital communication setup or panel modifications
Solution Approach 2:
The system utilizes existing infrastructure components (circuit breaker cables, dry contact inputs) to perform measurement functions. The CT clamp automatically detects circuit current through electromagnetic induction, and the EVSE's existing dry contact logic is repurposed to trigger charging alignment, making the system self-configuring without requiring additional installation complexity
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 solution enables automatic alignment of EV charging load with whole circuit consumption without the need for additional expensive meters, ensuring efficient and cost-effective operation while maintaining safety and adaptability.
Implementation Method 1
a current transformer (CT) clamp, which: a. is attached to the electrical circuit, and b. outputs an analog voltage through a wire proportional to the current passing through the electrical circuit
Data Source
AI summary
A system for dry contact-based automatic alignment of electric vehicle (EV) charging load to whole circuit consumption comprises an electric vehicle supply equipment (EVSE) including a charger relay circuit, a dry contact input and a current transformer (CT) clamp that is installed on an external electrical circuit to be measured against. The CT clamp outputs a signal that can be calibrated to generate an analog signal that passes a minimum threshold of the dry contact input. Normally the inputs at the dry contact input in the EVSE are programmed. A logic behind the external electrical circuit is modified to: a) turn off delivery of power to the EV when a calibrated current on the CT clamp is exceeded b) turn back on power to the EV if the calibrated current is no longer exceeded for over X seconds.