Page 26 - PEN eBook July 2022

Motor Control SMART ENERGY

and less reliable than ceramic capacitors. Moreover, the electrolytic capacitors are limited by the
RMS current that can flow through them. When the frequency is increased to 100 kHz, designers can
use ceramic capacitors such as X7R. The EPC9173 reference design provides for both electrolytic and

ceramic capacitors, giving designers a chance to select their preferred switching frequency and to add
or remove the capacitors as preferred.

Power tools with trapezoidal modulation
Many power-tool applications are still using trapezoidal-modulation schemes and related inverter
schematics. With the current-limiting cycle-by-cycle scheme and low-inductance motors, the lower
the PWM frequency, the higher the current ripple. This in turn generates heat and unnecessary power
dissipation. Using a GaN inverter with the same trapezoidal scheme makes it possible to increase the
PWM frequency and then reduce the current ripple, obtaining higher efficiency, less heat, and fewer

vibrations.

CONCLUSION Sun to Wheels:

When dealing with motor applications, GaN inverters can increase the efficiency of the system if PWM
frequency is increased, the dead time is drastically reduced, and the input capacitance is converted Powering a Renewable
from electrolytic capacitors to ceramic capacitors. Using EPC’s new GaN ICs, such as EPC2152 and
EPC23101, results in increased power density and system efficiency while saving much system design

effort. Future with Silicon
Carbide
References

By Guy Moxey, senior director for power products at Wolfspeed
▶ A. Lidow et al. “GaN Transistors for Efficient Power Conversion.” Third
1
Edition, Wiley. ISBN 978-1-119-59414-7.
As the world advances toward a sustainable, greener future, many countries are powering down
fossil-fuel energy generation in favor of renewables. The global weighted-average cost of electricity
▶ A. Lidow. (2022). “GaN Power Devices and Applications.” Power Conversion from new utility-scale solar photovoltaic (PV) projects fell by 85% between 2010 and 2020, onshore
2
Publication. wind by 56%, and offshore wind by 48%. Renewables have thus become the typical route for energy
capacity addition in nearly all countries, and the compound annual growth rate of cumulative PV
▶ M. Palma et al. (2021). “GaN Devices for Motor Drive Applications.” 2021 IEEE installations, including off-grid, reached 34% between 2010 and 2020. 1
3
8th Workshop on Wide Bandgap Power Devices and Applications (WiPDA),
This growth is set to continue with the added thrust toward increasing energy efficiency. An
pp. 146–151.
International Renewable Energy Agency (IRENA) report asserts that limiting global warming to 1.5˚C

would require cutting 36.9 gigatons of annual CO emissions and has recommended a target of
2
▶ D. Cittanti et al. (2021). “PWM-Induced Losses in Electrical Machines: An an additional 444 GW/year of solar PV and 248 GW/year of wind energy until the year 2050. IRENA
4
Impedance-Based Estimation Method.” 2021 24th International Conference on estimates that significant increases in renewable energy and energy efficiency can each contribute
Electrical Machines and Systems (ICEMS). no less than 25% toward achieving the targeted emissions reduction, while another 20% can be
reached through electrification of such applications as transport. 2

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