S. Hansen et al., An integrated single-switch approach to improve harmonic performance of standard PWM adjustable-speed drives, IEEE IND AP, 36(4), 2000, pp. 1189-1196
In this paper, an integrated single-switch approach to improve harmonic per
formance of standard pulsewidth modulation adjustable-speed drives (ASD's)
is presented. The approach is essentially an add-on solution to a standard
ASD topology. The approach is based on circulating a third harmonic current
to reduce the harmonics of the line current. The dynamic braking chopper a
vailable in standard ASD's is used to control the amplitude of the third ha
rmonic circulating current. Analysis, design, and simulations are presented
to determine the performance of the proposed scheme with different line im
pedance and with and without de-link inductance in the ASD, Utility input c
urrent distortion well below 15% is obtained. This paper also presents how
this new approach is capable of reducing the harmonic distortion in multipl
e drives. The paper includes experimental results using a 480-V 10-kW comme
rcial ASD retrofitted with the proposed approach.