Distribution Transformer EV Charging Control Under Load Limits
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Solution Overview
Problem
The rapid adoption of electric vehicles (EVs) is overloading existing distribution transformers and primary cables, threatening equipment failure and requiring urgent infrastructure upgrades, as traditional grid systems were not designed to handle such high loads.
Innovation Solution
A wireless communication system using microcontrollers with temperature and current sensors at transformers, coordinating with EV chargers to schedule charging based on vehicle state and user input, ensuring transformers operate within safe limits and prolonging their lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple EVs charge at high rate (19 kW) on a single distribution transformer, then charging speed and user convenience are improved, but transformer loading exceeds design capacity causing equipment failure
Solution Approach 1:
The system dynamically adjusts EV charging rates based on real-time transformer loading conditions. The controller monitors transformer status and modifies charging power levels accordingly, transitioning from static fixed-rate charging to dynamic adaptive charging that responds to grid conditions
Solution Approach 2:
The system implements periodic monitoring of transformer loading and cyclic adjustment of charging rates. Rather than continuous high-power charging, the system periodically assesses transformer status and adjusts charging in cycles, allowing transformer cooling and preventing thermal overload
2Duration of action of stationary object
If EV charging load is limited to protect transformer, then transformer lifespan is extended, but charging capability and user satisfaction are reduced
Solution Approach 1:
The system employs feedback control where the controller continuously monitors transformer loading, temperature, and health status, then adjusts charging rates in response. This closed-loop control ensures transformer protection while maximizing charging capability within safe operating limits
Solution Approach 2:
The system performs preliminary assessment of transformer capacity and charging demands before initiating high-power charging. By pre-evaluating system state and scheduling charging sessions, the system prepares protective measures in advance, allowing higher overall charging throughput while preventing overload damage
Data Source
AI summary
Electric Vehicles (EV's) are becoming common place and uncontrolled charging eventually will require upgrading existing electrical infrastructure before the end of life of the equipment. By considering the loading on the existing transformer and not charging all vehicles on the transformer at the same time, existing distribution transformers can remain in use for their normal lifespan without degradation. Examining the load involves using data collected from sensors on the transformer and chargers connected to the transformer, and incorporating current limiting functions to maximize charging capability without harming the existing distribution network. The present invention uses a wireless (Wi-Fi, Bluetooth, radio etc.) communicating microcontroller in the distribution transformer to communicate with another wireless communicated device that is talking to the electric vehicle. With the given data, an electrical board that is in the transformer will provide charging direction in terms of time and total current draw. The present invention will enable controlled charging of multiple EV's.