Bidirectional EV Charging Station Grid Energy Management

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Solution Overview

Problem

Current electric vehicle charging systems are inefficient due to AC-DC conversion losses and lack flexibility in utilizing surplus battery charge for grid support, especially when primary AC power sources are insufficient or expensive.

Innovation Solution

A charging station with a DC charger and inverter, controlled by a controller, that selectively switches between modes to provide DC power to the vehicle battery or draw power from the battery to supply the grid, optimizing energy usage based on price rates, grid stability, and renewable energy availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If AC power is used to charge the vehicle battery through an AC charger, then the vehicle can be charged from the power grid, but energy is lost during AC-DC conversion through internal rectifier circuitry

Engineering Contradiction:

Improveenergy loss during AC-DC conversionVSAvoidcharging flexibility

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent extracts the rectifier function from the vehicle's onboard AC charger and relocates it to the charging station. The charging station includes a rectifier that converts AC power to DC power before transmission to the vehicle battery, eliminating the need for the vehicle's internal AC-DC conversion and reducing energy losses.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The charging station acts as an intermediary between the AC power grid and the vehicle battery. It includes a rectifier that converts AC to DC, and a DC-DC converter that conditions the power for battery charging, thereby mediating the power transfer and eliminating direct AC-DC conversion in the vehicle.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the vehicle battery is charged to full capacity, then the vehicle has sufficient range, but surplus battery charge cannot be utilized for grid support or energy management

Engineering Contradiction:

Improveenergy utilization flexibilityVSAvoidwasted surplus battery charge

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The charging station is designed with multi-functionality to handle both charging and discharging operations. It includes a bidirectional DC-DC converter that can transfer power in both directions: charging the vehicle battery from the grid and exporting surplus battery power back to the grid or local loads, thereby enabling versatile energy management.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system incorporates a controller that monitors battery state of charge, grid conditions, and energy prices to make intelligent decisions about when to charge and when to discharge. This feedback mechanism enables optimal energy management by utilizing surplus battery charge when beneficial and avoiding waste.

Inventive Principle:

Principle #23Feedback

3Loss of energy

If a DC charger is implemented to provide direct DC power to the vehicle battery, then energy conversion efficiency is improved, but the device complexity increases due to additional components

Engineering Contradiction:

Improveenergy conversion lossVSAvoidcharging station complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated components at the charging station. The rectifier, DC-DC converter, and control systems are merged into a unified charging infrastructure, consolidating complexity at the stationary facility rather than requiring complex systems in each vehicle.

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 reduces energy losses by directly charging vehicles with DC power and providing surplus energy to the grid, enhancing energy efficiency and user savings while supporting grid stability and renewable energy utilization.

Implementation Method 1

The inverter includes a DC input operative to receive DC input power and is operative to convert DC input power to drive an inverter AC output to provide AC output power to the AC power grid

Methodology Applied

Scientific EffectDC to AC conversion:

Implementation Method 2

The PEV generally includes an AC charger that can receive AC power from an AC power source. However, the PEV operates on direct current (DC) power from an on-board vehicle battery, and AC chargers must convert AC power to DC power via internal rectifier circuitry

Methodology Applied

Scientific EffectAC to DC conversion:

Implementation Method 3

The charging station provides power to the PEV battery in certain operating modes, and may employ such alternative sources, for example, when a primary AC power source cannot provide sufficient power

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS9153847B2Grid connected solar battery charging device for home and vehicle energy management

Publication Date: 2015.10.06 HONDA MOTOR CO LTD

AI summary

A battery electric vehicle charging station is disclosed, having grid and vehicle connections with a DC charger and controller that selectively charges the vehicle battery directly with DC power in a first mode and converts DC power from the vehicle battery to drive an inverter in a second mode to provide AC power to a power grid.