Page 25 - EE Times Europe September 2021

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Eggtronic Enables GaN-Based Charging for EVs

Figure 2: E Watt efficiency (Source: Eggtronic)
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lithically integrated analog drive circuits and receiver] is minimized using a second control frequent charging is a short-term goal to sup-
digital logic circuits integrated on the same loop that ensures minimum reactive energy in port EV adoption. Larger battery size as well
chip as the GaN power device. GaNFast power the system, Spinella said. as the higher rate of current flow and heat
ICs are rated at 2 MHz. High-speed operation Wireless charging is undeniably faster, generation are also considerations. Therefore,
offers reductions in size and the cost of power easier, and more convenient than wired integrating technology into electric cars and
conversion for fast-charging systems. alternatives. Not only is it more efficient, installing municipal and private charging
In addition to GaN technology, Microchip but it provides better thermal performance. stations could eventually reduce the need to
Technology’s dsPIC33 microcontroller with The latter is often seen as a secondary design connect vehicles for charging. ■
core DSP, high-speed ADC, and high- consideration by developers looking to bring
resolution pulse-width modulation enables their products to market faster. Maurizio Di Paolo Emilio is editor-in-chief of
the E Watt’s digital architecture to offer The ability to provide more power with less Power Electronics News and EEWeb.
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feedback control of the transmission while
optimizing the charging distance. Thanks
to its proprietary receiver technology, the
platform enables a significant drop in receiver
temperatures, Spinella said.
The E Watt transmitter (Figure 3) uses
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logic to convert AC power from the grid into
another AC frequency to activate the coil.
The base consists of a half-bridge circuit by
Navitas to stimulate the LC tank, which com-
plies with the Qi standard. The architecture
allows for direct high-input voltage (elim-
inating the need for an AC/DC converter in
series) and allows for zero-voltage switching
(ZVS) without the use of the resonant LC
tank, ensuring that ZVS is achieved in most
load conditions. It also allows for continuous
control from light to full load without using
burst mode, said Spinella. ZVS also reduces
the capacitive switching losses at turn-off
and turn-on, thereby eliminating the capac-
itive turn-on loss. That makes the approach
suitable for high-frequency operation.
The receiver acts both as a rectifier and as
a non-dissipative regulator. This is achieved
by controlling the ratio between active power
delivered to the load and reactive power
reflected to the primary side. “The reactive
power in the wireless system [transmitter and Figure 3: Block diagram of E Watt technology (Source: Eggtronic)
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www.eetimes.eu | SEPTEMBER 2021