PRODUCTS & SERVICES
E-drive innovation
How smart technology is being employed to simultaneously improve e-drive
energy efficiency, performance, mass and cost
Hybrid Permanent Magnet-assisted Synchronous Reluctance (HSM) electric
machines with MavelTech enhances effi ciency throughout the operating range
www.electrichybridvehicletechnology.com // July 2019 // 203
Nestled in the Italian Alps,
away from the hustle and
bustle of the world’s automotive
capitals, a committed team of
engineers at Mavel is at work
developing the next generation of
electric machines. While the initial
shift to EVs and PHEVs yielded
a massive gain in vehicle energy
e iciency, the ‘game is on’ to
implement new technologies that
will progressively make electric
propulsion more e icient still, with
widespread benefits in drivability,
driving range and – both directly
and indirectly (through smaller
batteries) – vehicle mass and cost.
Particularly for automotive
traction applications, MavelTech
technologies are maximizing the
potential of Hybrid Permanent
Magnet-assisted Synchronous
Reluctance (HSM) electric
machines. Although the HSM
topology currently o ers the best
balance of attributes – given its
inherent e iciency, output density,
and (lower) copper and magnet
content – there are hurdles. HSM
maximum speed is typically limited
by rotor flux barrier ‘bridge’
mechanical constraints, and are
challenging to control, which as a
result then require precise magnetic
fields misalignment and position
sensor measurements.
The following are some of the
solutions developed and
implemented by Mavel, and their
combined benefits. Regarding
inverters and controls there is (a)
VSSW – Variable Soft Switching –
to reduce IGBT overvoltage and
switching losses (while especially
suitable for high-speed machines,
it is still meaningfully beneficial for
traction units) and improve
e iciency and inverter durability by
autonomously varying switching
frequency according to motor RPM;
(b) ASVE – Adaptive State Variable
Estimator – for performance
optimization through precise motor
control in every region of the
operating range; (c) HRTD2 –
High Residual Torque at Deep
Deflux – to limit the gap between
the system’s ‘apparent power’ and
‘e ective power’ for cost and mass
optimization; (d) MSHP – Motor
State of Health Predictor – for
real-time monitoring of motor
vibration for early detection of
incipient failure.
The solutions for motors from
Mavel include: TFX – Tailored Flux
Barrier – to minimize ‘torque ripple’,
and associated NVH, without the
e iciency drawbacks of a ‘skewed’
design; ARC – Active Rotor Air
Cooling – for uniform temperature
distribution and magnet
temperature reduction at high
speed; and MPS – Multi-functional
Position Sensor – for precise rotor
and position sensor magnetic fields
alignment, and shaft acceleration
measurement, increasing power
throughout the whole speed range
and continuous system state-ofhealth
monitoring
The verified benefits of these
technologies in comparison to an
equivalent 100kW IPM (interior
permanent magnet) machine are
substantial, including: Vehicle-level
energy e iciency improvement
of 2% on WLTP, and significantly
more in the typical real-world
driving; 12% lower material cost
driven by lower ‘apparent’ inverter
power and lower copper and
magnet content: and 9% lower dry
weight, for the same reasons.
The first client electric machines
with the MavelTech technologies
are under development. The benefits
can already be experienced though,
as the first of Mavel’s own portfolio
of modular 350V e-drive units –
a 90kW and 160Nm integrated unit
for light vehicle applications – has
completed its development and
is being industrialized.
As EVs and PHEVs increasingly
become more mainstream, the
requirement for enhanced
performance/cost ratio will be ever
more pressing. For companies
looking to engage in a codevelopment
project (or purchase
and integrate a fully developed
and industrialized unit), Mavel
is a valuable partner.
Topology of MavelTech is shown on Mavel’s 90kW e-drive unit, which is designed
for light vehicle applications and currently being industrialized
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visit: www.magupdate.co.uk/PEHV
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