Ride-through study for matrix-converter adjustable-speed drives during voltage sags

The ride-through capability issues associated with adjustable-speed drives (ASD) have become an important area of concern due to the susceptibility of ASD to power interruptions. Furthermore due to the absence of the dc link capacitor in matrix-converters (MC), MC adjustable speed drives are more vulnerable to such power disturbances. This paper presents a study of a ride-through strategy for MC adjustable-speed drives. With hysteretic control on the magnitude of motor currents, the strategy comprises of keeping the motor continuously operating through a combination of input voltage vector application, aligned in the flux direction, and zero vector application, along with discontinuation of MC switches. The strategy aims to enhance the ride-through duration and achieve minimum possible flux deviation during the voltage sag period to allow minimum transients during power system restoration. The paper also investigates the effect of different load torques and reference currents at different voltage sags on the maximum possible ride through time.