Truck & Off-Highway Engineering - June 2022 - 10

TECHNICAL INNOVATIONS
ELECTRIFICATION
WAVE builds in-road inductive charging for large EVs
AVTA's fleet uses WAVE's
wireless chargers to help
power its battery-electric
buses. An in-road wireless
charging plate is shown in
front of the bus.
WAVE's CTO
Michael Masquelier.
" WAVE has
demonstrated
the ability to
scale to near
megawatt
levels,
previously
viewed as
impossible
for wireless
charging. "
scheduled to come to the depot for a midday charge because
of the miles required on those routes, " Rodriguez said.
At a scheduled wireless charging stop, an AVTA bus - fitThe
largest all-electric transit bus fleet in the U.S. serves as a
vivid example of commercial vehicles ditching diesel fill-ups.
" WAVE's wireless charging solution is purpose-built for medium-
and heavy-duty vehicles, and we remain laser-focused
on that sector, " said Michael Masquelier, chief technology
officer for Salt Lake City, Utah-based WAVE (Wireless
Advanced Vehicle Electrification).
Southern California's Antelope Valley Transit Authority
(AVTA) opted to transition from diesel-fueled to battery-electric
buses in 2014. Today, 48 of the current 54 BYD-built buses
are equipped with WAVE's patented wireless charging system.
Each BYD bus has two asynchronous three-phase motors. The
40-ft buses are 150 kW; the articulated 60-ft buses are 180 kW.
" Depending on the season, our cost of fuel - electric in this
case - is anywhere from 50 percent to 70 percent less than
our diesel fleet was. And we avoid about 2,700 metric tons of
CO2
ric tons avoided since we started the project, " said Esteban
Rodriguez, AVTA's director of Operations and Maintenance.
Wireless charging centers
Within a 100 sq. mi. (260 sq. km) area, AVTA has 12 wireless
charging centers, each providing 250 kW. " AVTA uses scheduling
software Optibus to optimize and extend the range of a
bus by adding en-route charging at designated layovers to get
a minimum of 10 minutes to a maximum of 20 minutes via
WAVE's inductive charging, " Rodriguez said.
Buses are charged overnight to provide a 100% state of
charge at the start of a day's route. " A handful of buses that
are not equipped with the WAVE charging equipment are
10 June 2022
emissions for every million miles driven, with 21,600 metted
with an undercarriage-mounted power receiver - is
parked on top of a ground-embedded transmitter packaged
within a ruggedized pad. " WAVE uses a single-pad design
that not only allows for a very sizable alignment window, but
it also helps deliver power transfer efficiency equal to or better
than some conductive chargers, " Masquelier explained.
WAVE's charging system typically reaches its maximum
power in a few seconds. " The pace at which full power is
reached is controlled by the vehicle's battery management system,
which varies based on a number of factors, including the
size of the battery pack and the pack's state of charge, "
Masquelier noted. The charging activity occurs within a 5- to
8-in. (127- to 203-mm) air gap between the vehicle and the
roadway. " We use a process called magnetic resonant inductive
power transfer, " he said.
Purpose-built for large EVs
To enable the inductive charging process, the all-electric buses
are fitted with a communications antenna, a system interface
controller, a user display and an undercarriage-mounted
power receiver that's positioned rearward of the front axle.
The wireless charging loop is completed via the in-ground
charging pads, each with an underground connection to an
above-ground box that contains the primary power electronics.
An adjacent above-ground box contains the primary power
supply with a cooling unit.
Seasonal weather changes are not considered problematic for
wireless charging. " With no moving parts, the ruggedized system
requires little maintenance. And being free of moving parts,
connectors or cables means there is nothing to break or freeze, "
Masquelier said. WAVE's wireless charging system substantially
differs from legacy plug-in and overhead charging systems.
TRUCK & OFF-HIGHWAY ENGINEERING
BOTH IMAGES: WAVE
Truck & Off-Highway Engineering - June 2022

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