CAR and Driver - March 2017

illustrations by CHRIS PHILPOT

60 – U.S. electric grid alternating current

148 – Ferrari F12tdf crankshaft rotation at redline

200 – Hummingbird wingbeat

1000 – Sensing frequency for magnetorheological dampers

3667 – Infiniti V-6 turbocharger peak rotation

7667 – Dental drill peak rotation

Hz so good

The frequency at which certain objects switch, spin, sense,

and search, in Hertz, or cycles per second:

Power inverter and

motor controller

SICK SIC IS SLICK

Silicon-

carbide

power

inverters

Increasingly, electricity is

the race fuel of the future.

Formula E recently saw an

influx of automaker cash, money that’s

being used to develop more-efficient

electric-drive systems, just as in

electric road-car research.

Battery-pack voltage is climbing in

Formula E, from around 670 cur-

rently to at least 800 by 2018, and

turning the direct-current (DC)

flow from the battery into the

three-phase alternating

current (AC) required by the

motor takes power inverters

that can handle a lot of juice

without getting hot, as

heat creates power-

sapping resistance.

These solid-state,

high-speed switching

mechanisms—basi-

cally semiconductors

that have two termi-

nals in from the battery

and three terminals out

to the motor—have to

switch up to 40,000

times per second to keep

up with the demands of

Formula E’s furious drive

motors. Use of silicon carbide in power inverters is

the breakthrough. Formed at temperatures about

3000 degrees Fahrenheit, SiC semiconductors only

0.2 inch thick can handle hundreds of amps in a

power inverter with 95 percent efficiency. The

downside is cost; one Formula E team said its last

chipset cost $18,000, so it may be a while before we

see this technology in street electrics.

SOME (NEW) BATTERIES
REQUIRED

FORMUL A E’S

NEXT-GEN BATTERY
Supplier McLaren Applied
Technologies, an offshoot
of the road- and racing-car
business, is mum on the
details of the changes to
the cells and the cooling
strategy, which is vital to
holding down the pack’s
temperature and making
the batteries last. Any-
thing above a mere
144 degrees Fahrenheit
would cook the current
batteries. But it’s known
that capacity will roughly
double in McLaren’s new
packs to 54 kWh, and it’s
certain that voltage will go
up to somewhere between
800 and 1000 volts.
Higher voltage means
lower amperage for the
same power, allowing for
thinner, lighter wiring and,
with an optimized cooling
system, less heat, which
allows heavier-duty cycles
with faster recharging.
Higher voltages create
an upward spiral of
benefits that the automo-
tive industry wants to
jump on for production
electric vehicles.

40,000 – Silicon-carbide power

inverter switching

63,000 – Google searches

Racing’s

offspring:

• Formula 1’s carbon-
  carbon brake tech
  descended to produc-
  tion cars as carbon-
  ceramic brakes on
  mega-exotics such as
  the Ferrari Enzo in

2002. Carbon-ceramics
      are now a common
      option on performance
      cars, from the Chevy
      Corvette to the BMW
      M3/M4.

• Ferrari introduced
  paddle shifting to F1 in
  1989, and by 1997 a
  street version was in
  production with the
  Ferrari 355 F1. Since
  then, single-clutch
  automated gearboxes
  have given way to
  smoother and quicker
  dual-clutch transmis-
  sions, and nearly every
  car, from the Bentley
  Continental to the
  Honda Civic hatch, has
  sprouted shift paddles.


• Modern F1 steering
  wheels are renowned
  for cramming together
  knobs and buttons.
  Such driver-changeable
  modes have migrated to
  road cars, with systems
  such as GM’s Perform-
  ance Traction Manage-
  ment giving Corvette
  drivers, for example, a
  wide range of stability,
  traction, and suspen-
  sion modes to choose
  from. We can also thank
  racing for the develop-
  ment of launch
  control—even though
  it’s outwardly banned in
  most series nowadays.


• Computer airflow
  simulation combined
  with actual wind-tunnel
  work is what gives some
  racers the edge in
  tightly regulated series.
  All this intense aerody-
  namic development in
  recent years has paid
  automakers real
  dividends, especially
  those trying to cut drag
  or induce downforce in
  high-performance
  models. Many produc-
  tion cars, such as the
  Acura NSX, have
  sprouted flying but-
  tresses or grown
  under-car air tunnels.


• Carbon fiber became
  the standard material
  for F1 tubs in the
  mid-1980s and eventu-
  ally filtered down. Its
  appeal to the wider auto
  industry has been
  obvious: high strength
  and low weight. Now
  that billions have been
  spent on its develop-
  ment, we see ever wider
  deployment, both as
  nonwoven molded
  composites for struc-
  tural and closure panels
  and as woven parts for
  roof panels and other
  exterior pieces.

Battery Pack

Power module

MOSFET

(metal-oxide-

semiconductor

field-effect

transistor),

one of the

controller’s

three solid-

state switching

devices

62. FE ATURE. CAR AND DRIVER. MAR/2017

Semiconductor

made from

silicon-carbide

wafer