EVSE Charging Level Adjustment via Load Center Monitoring
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Solution Overview
Problem
Residential electrical systems often face over-current situations when charging electric vehicles, leading to the tripping of main breakers due to excessive power draw, which can be exacerbated by simultaneous operation of other electrical components, exceeding the maximum amperage rating of the utility service.
Innovation Solution
A monitoring and limiting device (MLD) is integrated into the load center to monitor power or current usage of electrical loads and adjust the charging level setting of the electric vehicle supply equipment (EVSE) to prevent over-current situations, using wireless communication protocols like ZIGBEE to manage the charging level dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If EVSE charges electric vehicle at high current, then charging speed is improved, but main breaker trips due to exceeding maximum amperage rating
Solution Approach 1:
The system dynamically adjusts the charging current based on real-time monitoring of total load conditions. The EVSE controller receives signals from the load center controller that indicate current usage levels, enabling the charging rate to vary adaptively rather than operating at a fixed high current level.
Solution Approach 2:
A feedback loop is established where the load center controller continuously monitors power or current usage of electrical loads and communicates this information to the EVSE controller. The EVSE controller uses this feedback to adjust charging parameters, ensuring the total load does not exceed the maximum amperage rating and preventing main breaker trips.
2Loss of time
If EVSE operates at maximum charging capacity, then charging time is reduced, but over-current situations occur when other electrical components operate simultaneously
Solution Approach 1:
The system performs preliminary monitoring of load conditions before initiating or adjusting charging operations. The load center controller assesses current usage levels and communicates available capacity to the EVSE controller in advance, allowing the charging process to be optimized within safe current limits from the outset rather than reacting to over-current conditions.
Solution Approach 2:
The charging current parameter is dynamically changed based on the operational state of other electrical loads. When monitoring indicates low overall usage, the EVSE operates at higher current to reduce charging time. When usage approaches the maximum amperage rating, the charging current is reduced to prevent over-current situations.
3Reliability
If monitoring and control system is added to manage charging levels, then over-current protection is improved, but device complexity increases
Solution Approach 1:
A load center controller acts as an intermediary device that centralizes the monitoring and coordination functions. This single controller communicates with both the utility service and the EVSE, simplifying the overall system architecture compared to having multiple distributed monitoring devices. The intermediary manages power distribution and charging level adjustments through standardized communication protocols.
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
An electric vehicle charging system is disclosed. More particularly, the system encompasses a load center having one or more electrical loads coupled thereto, electric vehicle supply equipment (EVSE) to charge an electric vehicle (EV), and a monitoring and limiting device (MLD) to monitor power or current usage of at least the one or more loads coupled to the load center, and adjust a charging level setting of the EVSE based upon the level of the usage. MLD apparatus and methods of charging a vehicle with electric vehicle supply equipment (EVSE) are provided, as are other aspects.