Automotive Engineering - March 2021 - 34

READER
FEEDBACK

EV opinions, Hybrid questions

I really liked your Editorial about the Hyundai Kona EV
(Nov.-Dec.). I think my decision for a PHEV Toyota is smart,
especially considering the still-poor charging network in
Germany - and the extreme temperature range we have in
southwestern Germany.
Wolfgang Sexauer
Battery-electric vehicles are not really the
best way to go. Hydrogen fuel cell vehicles (HFCVs) are a better way and more
sustainable. The hydrogen generation and
delivery infrastructure does not exist, but
the existing oil/gas distribution systems
may be adaptable to low-pressure hydrogen. The BEVs are losers in the all-seasons game. HFCVs have the advantages.
H2 will go into the big commercial vehicles as a matter of economics, but
smaller passenger vehicle prices should
actually be lower than those for ICE vehicles. The current pricing is arbitrary.
Constantine Kortesis

Your editorial on the Kia Niro EV complements your Nov. 2019
feature story of a road trip in a battery-electric Jaguar that
took three times as long and cost four times as much as the
same trip in a 10-year-old BMW. And some wonder why battery electric cars still have less than a 2%
market share?
Also in the Nov.-Dec. issue there is a
graph predicting that the cost of lithiumion batteries will fall by about 60% by
2030. Two pages later there's a graph
predicting that BEV sales will increase
about 20-fold. My experience as a capitalist tells me that a 20-fold increase in demand is very unlikely to cause prices of a
key component to fall. A much more likely
outcome, especially since lithium-ion batteries rely on a natural resource that has
to be mined (usually in remote parts of
the world) is that the price will rise. Of
course, that might affect the predicted
20-fold increase in vehicle sales.
Bob Elton

About those hybrid P's

P0 (P-zero): This basic mild-hybrid system is commonly
known as a BSG - Belt-Starter Generator. It's the least costly
hybrid set-up, typically replacing the conventional 12-V alternator with a 48-V machine connected (by belt) to the combustion engine through its front-end accessory drive (FEAD). P0
hybrids offer start/stop functionality, regenerative braking, and
supplemental propulsion torque. They're input-torque limited,
however, and their belt drives incur parasitic losses.
The " P " nomenclature for hybrid-electric systems architecture
P1: This mild-hybrid arrangement does away with the belt
indicates the position of the electric machine, starting at the
drive. The e-machine is connected directly to the ICE's crankfront of the vehicle (P0) and working toward the rear (P4). Its
shaft. Examples include the 2009 Honda Insight and 2010
origin is not clear; we've heard that the P-nomenclature was
Mercedes S400 BlueHybrid.
devised by either a Bosch or Mercedes-Benz engineer but canP2: Popularized by Nissan and Hyundai, this configuration
not confirm either. The schematic below provides illustration:
positions the e-machine between the
ICE and transmission in the convenient torque-converter (bell housing)
space. Or it can be side-mounted and
connected via belt. P2 hybrids offer
greater energy recuperation potential.
P3 and P4: These layouts offer optimum energy recovery potential and a
modicum of electric drive. P3 systems
use a gearset on the output side to
connect the e-motor with the transmission, decoupling the motor from
the ICE. P4 hybrids connect the eREADERS: Let us know what you think about Automotive Engineering magazine. Email
machine to the rear axle via a gear
the Editor at Lindsay.Brooke@sae.org. We appreciate your comments and reserve the
mesh and can provide awd and torque
right to edit for brevity and clarity.
vectoring. - Lindsay Brooke, Editor
As a sophomore engineering student who plans to work in
mobility propulsion, I read the SAE Automotive Engineering
for the latest technology trends. I often see references to " P0 "
and " P2 " in your articles about Hybrid vehicles. What does
this mean, and where did this originate?
John Chen

34 March 2021

AUTOMOTIVE ENGINEERING

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Automotive Engineering - March 2021

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