Page 98 - NEW Armstrong Book - 2

Enhancing Industrial Drive
Energy Efficiency with
SiC MOSFETs
By Stefano Lovati
ndustrial power applications are based on powerful electric motors, which can be found in fans, pumps, servo drives, compressors, sewing machines,
and refrigerators. The three-phase electric motor is the most common type of motor, and it is driven by appropriate inverter-based drives. It can account for up to 60% of the entire power requirement of an industry, thus being essential for the drives to provide high efficiency levels.
In industrial power applications, electronics designers can achieve tremendous benefits by using silicon carbide– based transistors (SiC MOSFETs), which offer significant efficiency improvements, smaller heatsink size, and lower cost compared with traditional silicon-based solutions such as insulated gate bipolar transistors (IGBTs). SiC technol- ogy achieves very low drain-source on-resistance (RDS(on)) per
unit area, high switching frequencies, and negligible energy losses during the reverse-recovery phase that occurs follow- ing the turn-off of the body diode.
Inverter-based drive
The most common three-phase inverter-based drive cir- cuit is shown in Figure 1. This topology, widely used at industrial level, is based on two-level three-phase inverters, mostly using discrete or power-module IGBTs, depending on power requirements, plus free-wheeling diodes. The six power transistors are connected in three half-bridge legs, which generate three-phase AC for electric machines or other loads. Each half-bridge is forced to switch at a certain frequency on an ohmic-inductive load (the motor) to be able to control its speed, position, and electromagnetic torque.
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ASPENCORE GUIDE TO SILICON CARBIDE