AC Current Control for EV Onboard Chargers
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Solution Overview
Problem
Conventional onboard charging systems for electric vehicles inefficiently utilize AC power, leading to increased charging time and costs due to conservative assumptions about DC efficiency, which can result in reduced Amp-hours delivered to the battery and longer charging cycles, increasing the risk of fire and inefficiency.
Innovation Solution
An AC current-controlled charging system that establishes a maximum DC charging current based on real-time available AC power, using a dual feedback control loop to adjust the DC charging current, eliminating the need for redundant DC current sensors and reducing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conservative DC efficiency assumptions are used in conventional charging systems, then safety risks are reduced, but charging time increases and system efficiency decreases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors actual DC efficiency and adjusts AC current draw in real-time. The controller compares assumed efficiency with actual efficiency measurements and dynamically modifies charging parameters, replacing conservative static assumptions with adaptive feedback control to optimize both safety and charging speed.
Solution Approach 2:
The system transitions from static conservative efficiency assumptions to dynamic real-time efficiency measurement and adjustment. AC current limiting circuitry dynamically adapts charging parameters based on measured actual efficiency, allowing the system to optimize performance continuously rather than relying on fixed conservative estimates.
2Reliability
If conservative DC efficiency assumptions are used, then AC current draw is limited for safety, but full AC wall power is not utilized
Solution Approach 1:
The feedback control system measures actual DC efficiency in real-time and uses this information to safely increase AC current draw when actual efficiency exceeds conservative assumptions. This allows full utilization of AC wall power while maintaining safety through continuous monitoring and adjustment.
Solution Approach 2:
The system changes the operating parameters of AC current draw based on measured actual efficiency. When actual efficiency is higher than assumed, the controller increases AC current utilization; when lower, it reduces current draw, thereby optimizing power utilization while maintaining safety margins.
3Quantity of substance
If conservative DC efficiency is assumed, then fewer Amp-hours are delivered to the battery, but this increases charging time
Solution Approach 1:
The system uses feedback control to continuously monitor actual DC efficiency and adjust charging current accordingly. By measuring real-time efficiency and adapting AC current draw, the system maximizes Amp-hour delivery to the battery within safe operating limits, reducing charging time without compromising battery health.
Solution Approach 2:
The charging system dynamically adjusts current delivery based on measured actual efficiency rather than static conservative assumptions. This dynamic adaptation allows the system to deliver maximum safe Amp-hours to the battery, optimizing charging speed while maintaining safety margins.
4Reliability
If conservative DC efficiency assumptions are used, then auxiliary loads operate longer, but this increases energy consumption
Solution Approach 1:
The feedback control system reduces auxiliary load operation time by enabling faster charging through real-time efficiency-based AC current optimization. By measuring actual efficiency and adjusting charging parameters dynamically, the system shortens overall charging duration, thereby reducing the cumulative energy consumption of auxiliary loads like pumps and regulators.
Data Source
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AI summary
A charging system and method that improves utilization of available AC power during onboard charging of energy storage systems of electric vehicles. An onboard charging method for an energy storage system of an electric vehicle, the method using an AC power source, includes a) establishing a maximum DC charging current for the energy storage system responsive to a control signal indicating real-time available current/power from the AC source; and b) controlling a charging system to provide an actual DC charging current, up to the maximum DC charging current, to the energy storage system.