Truck & Off-Highway Engineering - April 2024 - 23

TESTING | ELECTRIFICATION FEATURE
Electrical system testing
Traditional ICE testing typically measures speed,
torque and a few temperatures, pressures and flows.
Very precise control of speed and torque is typically
not required in testing IC engines, so dynamometers
used for standard combustion-engine testing (for example,
water brake and eddy current) were never designed
to handle the types of precision required by
hybrid or electric powertrains. Nor can they test the
regenerative (motoring) modes of operation.
Hybrid/EV test systems must provide all the functionality
of traditional systems, with the added ability
to test high-power regenerative electrical drives, highvoltage
battery and charging systems and communicate
with any number of smart control modules.
For many larger hybrid/electric drivetrains, there is
a strong trend toward using higher voltage, higher
efficiency drive systems. Going from the traditional
12/24-volt DC electric system to one using 240 volts
AC will typically require one-eighth or less of the current
to deliver the same power. Not only is this more
efficient, but it also requires much smaller/lighter wiring
and smaller components to transfer the energy.
Many current designs operate at 800 volts or more,
making the vehicles even more efficient.
Hybrid and electric vehicles use four-quadrant motor/
inverter technology, meaning that the electric motor can
control velocity or torque in either direction - the motor
can accelerate, run and decelerate forward or backward.
A four-quadrant motoring dynamometer with the ability
to drive or load in either direction is essential to simulate/test
all modes of operation in a hybrid or EV. A
standard dynamometer is not capable of testing the
system during braking when it is in regenerative mode.
Creation of high-efficiency, AC-powered systems
typically involves the use of three-phase, inverterbased
technology to precisely control the electric
motor(s) in the system. These systems tend to be
very efficient but also generate a great deal of harmonic
distortion in the power output. So, in addition
to the motoring dynamometer, a hybrid/EV test system
typically includes a three-phase power analyzer.
This unit must be specifically designed to measure
high-power electrical values with a great deal of harmonic
distortion present.
To meet the need for a system that can fully test hybrid
and EV drive systems, SAKOR developed
HybriDyne, a comprehensive test system for determining
the performance, efficiency and durability of all aspects
of hybrid drivetrain systems, including electrical
assist (parallel hybrid), diesel electric (serial hybrid) and
full-electric vehicle systems.
HybriDyne integrates components of SAKOR's
DynoLab powertrain and electric motor data acquisition
TRUCK & OFF-HIGHWAY ENGINEERING
DynoLab can be adapted to automate all aspects of electric powertrain testing
including motors, inverters, batteries and other drivetrain elements.
and control systems. Coupled with one or more of its AccuDyne AC
Motoring Dynamometers, and one or more precision power analyzers,
the modular HybriDyne can test individual mechanical and/or electrical
components, integrated sub-assemblies and complete drivetrains with
a single system.
High-voltage battery simulation and testing
A critical element of hybrid or electric vehicles is the high-voltage
battery and charging system. To accurately test a high-voltage hybrid
or electric drivetrain, the test system must provide precise, repeatable
high-voltage DC power. Since battery performance changes over
time depending upon their charge state, ambient conditions and age,
April 2024 23
EV motor production test stand installed at a Tier 1 supplier's facility.
BOTH IMAGES: SAKOR TECHNOLOGIES
Truck & Off-Highway Engineering - April 2024

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