Page 24 - EE Times Europe November 2021 final

24 EE|Times EUROPE

Silicon Carbide Modules Unlock Higher Power Density in Motor Drives

ers can create noise on sensitive low-voltage
signals, such as those from current sen-
sors. The current sensor’s proximity to the
switching nodes makes them even more sus-
ceptible. This is true as well for the cabling
between the sensor and the controller, which
can pick up the noise as it is routed around
the system.
The sensor chosen by Wolfspeed requires
only a laminated U-shaped magnetic shield to
protect against external fields and homog-
enize the field. A ground layer in the PCB
blocks capacitive coupling from the busbar to
the sensor. The use of differential signaling
significantly reduces the impact of radiated
noise from the switching. Additionally, using
shielded, twisted-pair Cat 6 cabling between
Figure 7: The output busbar arrangement offers flexibility to enable applications the sensor boards and the controller ensures
requiring higher-current outputs from a single inverter. that any noise is common-mode on both
signals of the differential pair.

a compact PCB that can then be attached the need for a large ferromagnetic core TESTING PERFORMANCE
directly to an output busbar. The flexibility of (Figure 6). This assembly occupies A clamped, inductive-load, double-pulse test
the PCB mount allows simplification of the 91.6 mL against the 800-mL volume of was conducted under aggressive switching
output busing. Moreover, the MLX91208 uses another popular sensor assembly used in the conditions using a low gate resistance to
an integrated magneto-concentrator (IMC) automotive industry. validate the entire power loop. The
deposited on the CMOS die, which eliminates The high dV/dt rates typical in SiC invert- constant-current–load waveforms showed a

Figure 8: Inverter power losses (left) and efficiency (right) at 800 V, 10 kHz, 25°C coolant

Table 1:
The CRD00DA12E-XM3
achieves a power density
of 72.5 kW/L, which
is 3.6× higher than
that possible with an
equivalent-rated IGBT
design.

NOVEMBER 2021 | www.eetimes.eu