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converter module to the battery. The
WT5000 has a specified basic AC
power measurement accuracy of
±0.03% and a DC measurement
accuracy of ±0.07%. The
measurement bandwidths of 10MHz
for voltage and 5MHz for current
greatly exceed the switching
frequency of a solar converter, and
the sampling rate of 10Msamples/s
meets the data refresh rate required
to validate the fuel gauge system.
The wide dynamic current range of
the WT5000 is therefore also
indispensable for tests on energysaving
designs. Users are able to
make measurements on up to seven
inputs simultaneously and view
them all together on the highresolution
10.1in touchscreen.
The next Bridgestone World Solar
Team Challenge will take place in
2021, which may see even less
di erence between the teams due
to the use of high precision power
measuring instruments such as the
Yokogawa WT5000, to validate the
higher conversion e iciencies, and
the race will ultimately be decided
on aerodynamics, weight and its
distribution, and team decisions.
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is being measured in order to
validate it.
A variety of such high accuracy
measurements are required in the
development of a World Solar Team
Challenge car. With an e iciency
of 99.65% in a solar DC conversion
circuit, the maximum possible
improvement being chased is as
little as 0.35%. The accuracy of
the car’s ‘fuel gauge’, the on-board
sensor measuring the battery’s state
of charge, needs to be validated.
This system measures current
flowing into the battery (from the
solar panels) and flowing out of
the battery (to the motor). By
subtracting the output from the
input, the residual charge in the
battery can be calculated. This
requires extremely accurate
continuous measurement of current
flows. The power output of the
motor system, including the inverter
and the motor itself, needs to be
measured at a range of power input
values, to be able to refine the
design and incrementally improve
its e iciency. This requires extremely
accurate power analysis at a high
sampling frequency.
The Yokogawa WT5000 Precision
Power Analyzer is meeting these
solar race team needs. In one case,
the power measurement of the
WT5000 was seen to be so precise
that it detected a small power loss
attributed to a change of resistance
in the connector linking the solar
Using a 2.64m² Gallium Arsenide solar panel to power an engine integrated into its
rear wheel, a power analyzer helped the team measure and maximize its effi ciency
Measuring only 2.9m (9.5ft) long and
1.4m (4.5ft) wide, the Red E was the
smallest car in the competition
The WT500 Precision Power
Analyzer provides simultaneous
measurement of voltage, current,
power, and harmonics
Photo: Martina Ketelaar.
Photo: Martina Ketelaar.
/PEHV
/www.electrichybridvehicletechnology.com