IEEE Power Electronics Magazine - March 2022 - 45

Copper Pour
The two points acting as signal points can also be routed
as differential pairs for better accuracy and easy routing.
Via Stitching
FIG 7 High current routing of power traces.
be added to stitch traces or polygon pours on multiple layers
to conduct high current, as shown in Figure 7.
■ Thermal Management-With high-level integration
and high current capacity, these integrated gate drivers
and MOSFETs dissipate power from ohmic loss
() .RDSon
A design engineer takes every step to minimize these
losses, but they cannot be eliminated. The best way to
provide thermal management is to provide copper pours
for the components with high power dissipation. Thermal
vias also help in transferring heat from the power
devices. As shown in Figure 7, we can see that MOSFETs
T1 to T6 have solid copper beneath them with thermal
vias to transfer heat away from the components. A combination
of thermal vias with solid copper acts as a miniature
heat sink and is the best ally of design engineers
for thermal management.
■ Current Measurement-FOC algorithms require accurate
current sensing. Therefore, the sense resistor and the
sense amplifier design are critical. A Kelvin connection
ensures the accuracy of the current measurement by providing
a four-wire connection, as shown in Figure 8.
Summary
This article aims to provide a quick reference guide on
designing BLDC motor controller hardware. A basic introduction
of different motor controller components has been
provided along with their function. Different types of integration
levels available in off-the-shelf gate drivers have
been highlighted. The use case for integrated gate driver in
low voltage medium current application has been established
with a comparative evaluation based on BOM and
design complexity. Then a step-by-step guide to manufacturer-independent
component selection for a BLDC motor
controller prototype has been laid out to enable the enduser
to design their hardware. This document also pointed
out the main design challenges and constraints to consider
when designing the PCB for the hardware. A list of references
to enhance the knowledge in the domain has also
been included for enthusiastic readers.
About the Author
Prabhat Ranjan Tripathi (iamprt@ieee.org) leads the
Power Electronic System Design group at FleetRF Pvt. Ltd.,
New Delhi, India. He received his B. Tech from SRM University,
Chennai, India in 2012, specializing in electrical and
electronics engineering. He was a doctoral candidate in the
electrical and electronics engineering department, Birla
Institute of Technology, Mesra, Ranchi, India, till August
2021. He has been a visiting student at the center of
research on microgrid (CROM), Aalborg University, Denmark
[May-December 2020] and the Electrical Engineering
Division at the University of Cambridge, UK [September
2017-March 2018]. He has hands-on experience in the hardware
design of various DC-DC, DC-AC converters, motor
controllers, and battery management systems. He is a senior
member of IEEE (IES, IAS, PES, and PELS).
Current
Flow
Direction
References
[1] " Application note, best practices for board layout of motor drivers, " 2021.
[Online]. Available: www.ti.com
[2] " Motor control and drive design solutions motor control and drive, "
White Paper. [Online]. Available: www.microchip.com/motor
[3] " The changing face of industrial drives, " Infineon, White Paper, 2019.
[Online]. Available: www.infineon.com
[4] I. Husain, S. Hasan, R. Veillette, and J. Carlotta, " Power Generation in
Series Mode, " IEEE Ind. Appl. Mag., vol. 16, no. 2, pp. 12-21, Mar. 2010, doi:
10.1109/MIAS.2009.935493.
[5] " Global sliding-mode control. Improved design for a brushless DC
motor, " IEEE Control Syst., vol. 21, no. 3, pp. 27-35, Jun. 2001, doi:
10.1109/37.924795.
Kelvin Connection Points
FIG 8 Kelvin connection for current measurement through the
sense resistor.
[6] T. Maetani, S. Morimoto, K. Yamamoto, Y. Isomura, and A. Watanabe,
" Comparing brushless DC motors: A method of suppressing the shaft voltage
even in a grounded motor frame, " IEEE Ind. Appl. Mag., vol. 21, no. 6, pp.
29-35, Nov. 2015, doi: 10.1109/MIAS.2014.2345800.
March 2022 z IEEE POWER ELECTRONICS MAGAZINE 45
http://www.ti.com http://www.microchip.com/motor http://www.infineon.com
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