EV Charging Circuit with Bidirectional Power Buffer

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Solution Overview

Problem

Electric vehicle charging stations face challenges in meeting the increasing power requirements of electric vehicles without exceeding grid capacity, which can destabilize the grid and damage charging circuit elements due to high input currents.

Innovation Solution

The electric vehicle charging circuit incorporates a first power converting circuit with AC/DC and DC/DC converters to convert grid voltage to a bus voltage, and a second power converting circuit with isolated bidirectional converters to manage power between a power storage device and the bus, allowing for bidirectional power transmission and controlling the output current to meet charging demands without exceeding grid limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high power is used to charge electric vehicles quickly, then charging time is reduced, but grid stability deteriorates and circuit elements are damaged due to excessive input currents

Engineering Contradiction:

Improvecharging speedVSAvoidgrid stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces a power storage device (battery) as an intermediary between the grid and the EV charging system. This mediator buffers the power flow, allowing the system to deliver high charging power to EVs while drawing limited power from the grid, thus preventing grid instability and circuit damage while maintaining fast charging capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary charging of the power storage device from the grid at normal power levels, then uses the pre-charged storage device to provide additional power during EV charging. This preliminary energy storage action enables subsequent high-power delivery without immediately stressing the grid

Inventive Principle:

Principle #10Preliminary action

2Productivity

If high power is used to charge electric vehicles quickly, then charging time is reduced, but the input current exceeds the rated limit causing circuit damage

Engineering Contradiction:

Improvecharging speedVSAvoidcircuit damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The power storage device serves as a protective intermediary that decouples the high-power EV charging demand from the grid connection. By buffering power through this intermediary, the system achieves fast charging while preventing excessive input currents that would otherwise damage circuit elements

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system provides beforehand cushioning by using the power storage device to absorb and regulate power fluctuations. This cushioning effect protects the circuit from harmful current spikes while enabling high-power charging operation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If grid power alone is used for charging, then the system is simple, but it cannot meet increasing power requirements without exceeding contract capacity

Engineering Contradiction:

Improvepower capacity flexibilityVSAvoidsystem structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The power storage device performs multiple functions: it stores energy from the grid for later use, provides supplemental power during EV charging, and acts as a buffer to manage power flow. This multi-functionality enables the system to meet varying power demands without proportionally increasing system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the grid power source with the power storage device to create a hybrid power system. This combination allows the system to leverage both the unlimited capacity of the grid and the immediate response capability of the storage device, achieving adaptability while maintaining reasonable complexity through integrated design

Inventive Principle:

Principle #5Merging (Combining)

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 efficient charging of electric vehicles by balancing power from the grid and a power storage device, ensuring stable grid operation, reducing the risk of circuit damage, and allowing for flexible expansion to meet increasing power needs while maintaining cost-effectiveness.

Implementation Method 1

an AC/DC converter configured to convert an AC voltage to a bus voltage to the bus

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS10752118B2Electric vehicle charging circuit and control method thereof

Publication Date: 2020.08.25 DELTA ELECTRONICS INC(CN)

AI summary

An electric vehicle charging circuit includes a first power converting circuit configured to provide an output current to charge an electric vehicle, a power storage device, and a second power converting circuit electrically coupled between the power storage device and a bus, and configured to bi-directionally transmit power between the storage device and the bus. The first power converting circuit includes an AC/DC converter configured to convert an AC voltage to a bus voltage to the bus, and a DC/DC converter electrically coupled to the AC/DC converter at the bus and configured to output the output current. The second power converting circuit includes an isolated bidirectional converter.