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Most convertors suffer from a problem
called switching loss. To convert from DC to
AC, an invertor uses switches - transistors
- that turn on and off frequently. However,
every time a switch opens or closes, some
power is dissipated as heat. This results in lost
energy that can no longer be used for driving
an electric motor.
A solution to switching losses exists, and it’s called
soft-switching. Compared to the most straightforward
method of building inverters (called hard-switching),
soft-switching uses an auxiliary circuit to control the
timing of the switches in such a way as to eliminate
power losses. However, soft-switching techniques are
difficult to implement, and typically work within a
limited range of power inputs and outputs. Thus, soft-
switching hasn’t proven effective in real-world applica-
tions like EVs.
Now, Renouard’s company has looked at the soft-
switching technique and reworked it to come up with a
new solution: pre-switching. Using an auxiliary circuit
along with artificial intelligence (AI) algorithms, pre-
switching promises to virtually eliminate switching
losses while remaining adaptable to a wide variety of
inputs.
Pre-switching
Pre-Switch is a solution that augments an existing
inverter with a few additions: some passive compo-
nents, an active switch, and an integrated circuit that
Pre-Switch calls the Pre-Flex IC. This IC contains
Pre-Switch’s AI algorithms, which are implemented
on a field programmable gate array (FPGA). The IC
monitors information about the inverter and uses it
to control the timing of its switches.
“We listen to about twenty different parts of the
system,” explained Renouard. “We do a very fast ana-
log to digital conversion, and then we pump that digi-
tal information into our algorithm.” The algorithm’s
output is simple: it controls the timing of the aux-With AI algorithms,
pre-switching
promises to
virtually eliminate
switching losses
while remaining
adaptable to a wide
variety of inputs.
Pre-Switch augments
an existing inverter with
some passive components,
an active switch, and an
integrated circuit that Pre-
Switch calls the Pre-Flex IC.
THE TECH