inverters for electric vehicle chargers - artemis-ioe.eu · pdf filedr. ashot melkonyan, dr....

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DC/DC converter for bi-directional battery charger using SiC power switches

Dr. Ashot Melkonyan, Dr. Kai Kriegel

Siemens AG, CT RTC PET POE-DE, Munich

Inverters for Electric Vehicle Chargers

“ecoCity eMotion” 24-25th September 2014, Erlangen, Germany

European Conference on Nanoelectronics and Embedded Systems for Electric Mobility

http://www.artemis-ioe.eu/events/ecar_home.htm


1. The role of bi-directional charger in energy management system

2. Architecture of the battery charger and grid inverter

3. Short topology description of the DC/DC converter and the power switches demands

4. Improvements of the commutation processes by using SiC devices

5. The prototype power board and summary

Overview


1. The role of bi-directional charger in energy management system

Bi-directional power flow

• Increase of localised electric power generation through renewable

technologies demands a grid stabilization and its robust regulation.

• Vehicle-to-Grid (V2G) integration enables an Electric Vehicle owner to

transfer energy from the EV traction battery back to the grid at times of

peak-loading, in exchange for some cost-benefit incentive.

For smart grid interfacing an isolated

bi-directional converter is required !


=

3 ~

M

=

3 ~

M

3-phase motor inverter

Renewable energy source

Battery

380 V

~

=

=

=

The Smart Grid and Electric Vehicles integration concept

Mass-produced electric vehicles or PHEV (plug-in hybrid) can be used as

a mobile intermediate electrical energy buffer

Battery charging, power flow control

and galvanic isolation

Grid interfacing and power

factor correction


General AC-DC / DC-AC converter architectures with Grid Interfacing Power Factor Correction

Switch mode AC/DC

Rectifier / Battery charger

Isolated Non-Isolated

Bidirectional Unidirectional Bidirectional Unidirectional

Single stage Two stage Two stage Single stage Two stage Single stage Two stage

2. Architecture of the battery charger and grid inverter

Single switch, multi-swicth, resonant, bridge / H-bridge, reconfigurable,

two level, multilevel, voltage source, current source etc. topologies


3. Bi-directional isolated AC/DC rectifier – DC/DC converter

~

Bidirectional

DC/DC converter (isolated, full bridge)

Energy Storage (Battery)

Filter

Active Front-End rectifier

(non-isolated PFC)

Bi-directional isolated

two-stage converter with PFC

PFC is realized at Stage I

• Easy reconfigurable for single and 3-phase systems

• Inverter control is realized by means of FOC

Galvanic Isolation is realized at Stage II

• DC/DC buck conversion using transformer

• Accurate output current and voltage control

• EMI reduction due to soft switching and isolation transformer

I stage

II stage


~

=

HF Bidirectional DC/DC converter - inverter

=

= 700V DC Grid

380 V

Topology of the integrated battery charger / inverter

Battery

(B) (C)

380V

DC

Bu

s

Batt

ery

DC/DC converter 150kHz 17 kHz DC/AC grid inverter

70

0V

DC B

us

Stage I

350V - 400V 600V - 700V

Bi-directional battery charging

Stage II

650-700Vdc 380Vac

Bi-directional grid inverter

SiC


3. Topology description – hard and soft switching operation modes

During commutation the current flow direction is:

from the switch to the diode

Soft switching

D3

D4

Current flow direction during commutation is:

from the diode to the switch

Hard switching


+

4. Improvements of the commutation processes by using SiC

Switching with SiC JFET and LV

mosfet cascode (1200V)

Switching with MOSFET and

ultrafast soft recovery diode (600V)


5. Power Board of the 3 Phase Bi-Di Charger / Inverter

3phase bi-di Charger / Inverter

DC Input

uC Connector

Low Voltage

Gate Driver

SiC Gate Driver

Low Voltage

DC Bus

AC Grid Relais

HV DC Bus

DCAC

Gate Drivers

DCDC Trafo

AC Filter

Inductors


First results of the bidirectional DC-DC converter (DAB)

Boost mode operation

discharging battery and recuperating energy into AC Grid

Buck mode operation :

Charging battery from AC Grid


Summary

Decentralised electric power generation through renewable technologies

requires a strong and stable utility grid with robust and smart regulation

Bi-directional power converters are the enabling technology to interact the Electric Vehicles

with Smart Grids. Implementing a bi-directional vehicle-to-grid communication and controlled

battery charging, this technology enables an effective integration of the electric vehicles and

their charging infrastructure into energy management system. (e.g. in Building Energy Manager)

Using bi-directional converters, the mass-produced electric vehicles or PHEV (plug-in hybrid)

can be turned into mobile intermediate electrical energy buffers.

Progress beyond the state of the art has been made by bi-directional on-board chargers – scalable

through modularity, efficient, compact and light-weight.

A 6kW soft switching converter system has been designed, constructed and validated, which

weights ~9kg incl. forced air-cooling and achieved over >96% efficiency.

With new SiC transistors very high current slew rates can be handled. This results in excellent

dynamic behavior and lower EMI under hart-switching operation modes.


Thank

for your attention !

inverters for electric vehicle chargers - artemis-ioe.eu · pdf filedr. ashot melkonyan, dr....

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