Reza Tavakoli, Aleksandar Jovicic,Niranjan Chandrappa, Ryan Bohm, and Zeljko Pantic (Assistant Professor)

Utah State University

Design of a Dual-Loop Controller forDynamic Wireless Charging of an Electric Bus

SELECT Annual Meeting and Technology Showcase – Logan, Utah – September 27-28, 2016

MOTIVATION In the past decade, there has been a significant interest toward transportation electrification and more specifically

electrification of roadways.

Limited onboard energy and power storage is identified as the main challenge toward successful implementation of

Electric Vehicles (EVs).

Emerging technology of Dynamic Wireless Power Transfer (DWPT) offers an alternative solution for limited onboard

energy resources through hybridization between vehicles battery storage and the power grid.

This technology not only extends the EV range significantly but also results in the considerable reduction of battery size

and capacity.Retrieved from: http://money.cnn.com/2015/08/18/technology/uk-electric-cars-roads/

PROBLEM STATEMENT

Sec.Comp.

Buck Battery Pack

Pri.Comp.

Inverter 20-100 kHz

AC Main( 60 Hz)

Primary coils

Secondary coil

PrimaryCurrent

Pri

ma

ry S

ide

Seco

nd

ary

Sid

e

• Energize Primary Coils Successively

• Control the primary coil current at the reference value

• Limit the transferred power

SYSTEM OVERVIEW

Current Controller Giv(s)

Power Controller

Gpi(s)PDC

P*

PDC

Err I* IPri,RMS

SS model ofLCC & Primary coil

SS model of LCC & DC link

Err Vinv,f

EVDS signal

Controller System Model

IPri

PIController

Initial Start-up

I*

IPri

Vinv,fPI

Controller

Equation

I*

IPri

P*

PDC

CONTROLLER OPERATION

BatteryCurrent

PrimaryCurrent

BatteryCurrent

PrimaryCurrent

BatteryCurrent

PrimaryCurrent

INITIAL START-UP

Pri

. Cu

rren

t (A

)

RM

S P

ri. C

urr

ent

(A)

Energizing of each primary coil is initiated after EV is detected:

Feedforward loop (6 ms)+Delay (1.5ms)+ PI controller (2.5 ms) = 10 ms

SEGMENTED COIL OPERATION

• When the detection system detects an

EV, the controller automatically

energizes the 1st coil.

• If the PDC is more than the limit (20

kW), the controller reduces the primary

current to keep the transferred power

constant.

• When the power transfer is finished,

the controller turns off the primary coil.

• The controller estimates the EV speed

and energizes the 2nd coil after a

calculated delay.

• This activation scheme can be repeated

for additional coils in the same manner.

ACKNOWLEDGMENTFunding provided by USTAR, the Governor’s Office of Energy Development in Utah, and Utah State

University. The Authors acknowledge research support from the Electric Vehicle and Roadway group

at Utah State University.