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CGD12HB00D DIFFERENTIAL
TRANSCEIVER COMPANION TOOL
• CGD12HB00D Differential
Transceiver Companion Tool
• Single-ended inputs for interfacing
with 3.3V or 5V microcontrollers
• Differential outputs for increased
noise immunity
Learn more >
The high density and maximized efficiency were essential,
given the need to optimize space and weight in an electric
vehicle. Wolfspeed's OBC solution consists of a bi-directional
AC-DC converter followed by an isolated bi-directional DC-DC
converter, as it was found to provide high efficiency and a wide
output voltage range in both charging and discharging modes.
To address conduction losses, the company eschewed a
conventional PFC boost converter as the conduction losses of
the diode bridge rectifier are not efficient, nor does it support bi-
directional operation. Because of the favorable reverse recovery
performance of the body diode of SiC MOSFETs, an interleaved
CCM totem pole PFC is enabled as the front-end stage of a
3.3kW OBC instead.
Thermal management is also critical when designing an
OBC. Typically, MOSFETs in a TO-247 package are reverse-
assembled on the PCB then mounted on a flat cooling
baseplate. However, since MOSFETs are bent down, the PCB
area is increased. This negatively impacts the overall power
density of the system. So, a tooled heat sink was used to
accommodate both semiconductors and magnetics. Vertical
MOSFET assembly is made possible by mounting power
semiconductors on the outer side of the heat sink, which, in
turn, reduces the PCB footprint. Magnetics are then potted
using a thermal compound inside the slots of the heat sink. As
a result, the thermal resistance from the tooled aluminum (Al)
heat sink to the system cooling baseplate is low.
The experimental results for the SiC MOSFET-based 6.6kW
bi-directional OBC's converter operating in the charging mode
and discharging mode manifest both high efficiency and power
density. The result is that a bi-directional OBC not only charges
and cycles the battery efficiently, it can also more effectively feed
power back to the grid.
A Power-Efficient Prototype
By designing and evaluating a 6.6kW bi-directional OBC using
its new 650V SiC MOSFET, Wolfspeed has demonstrated how a
DC-link voltage range can be optimized to 385V to 425V per a
normal battery voltage range of 250V to 450V for an OBC.
Further, the prototype built verified the performance and thermal
integrity of the design. By integrating the power semiconductors
and power magnetics on the same tooled heat sink, high power
density and high efficiency can be achieved in bi-directional
high-power conversion applications such as an OBC, owing to
the low power loss of the 650V SiC MOSFET.
Wolfspeed PRODUCT SPOTLIGHT
CRD-3DD12P
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