TY - JOUR
T1 - Aliasing Suppression of Multisampled Current-Controlled LCL-Filtered Inverters
AU - He, Shan
AU - Zhou, Dao
AU - Wang, Xiongfei
AU - Blaabjerg, Frede
PY - 2022/4
Y1 - 2022/4
N2 - Multisampling control provides an attractive way to reduce the control delays in LCL-filtered grid-connected inverters. Thereby, the bandwidth and stability margin will be improved. However, high frequency switching harmonics (SHs) is introduced in the control loop when the inverter-side current is sampled. In order to investigate the effect of multisampled high frequency SHs, the relationship between the double-update pulse width modulation (PWM) and multi-update PWM is deduced through geometric deduction. It is shown that the multi-update PWM is equivalent to double-update PWM with sampling instant shift, and the equivalent Nyquist frequency is equal to the switching frequency. Moreover, the non-averaged value of current is sampled within one switching period and aliased low-order harmonics will appear in the grid-side current. Hence, filtering the multi-sampled SHs is necessary, and an improved repetitive filter is proposed to remove all the sampled SHs and keep the advantage of phase boost by using the multisampling control. The method is evaluated with a single-loop inverter-side current control, and its effectiveness is verified through the simulation and experiment.
AB - Multisampling control provides an attractive way to reduce the control delays in LCL-filtered grid-connected inverters. Thereby, the bandwidth and stability margin will be improved. However, high frequency switching harmonics (SHs) is introduced in the control loop when the inverter-side current is sampled. In order to investigate the effect of multisampled high frequency SHs, the relationship between the double-update pulse width modulation (PWM) and multi-update PWM is deduced through geometric deduction. It is shown that the multi-update PWM is equivalent to double-update PWM with sampling instant shift, and the equivalent Nyquist frequency is equal to the switching frequency. Moreover, the non-averaged value of current is sampled within one switching period and aliased low-order harmonics will appear in the grid-side current. Hence, filtering the multi-sampled SHs is necessary, and an improved repetitive filter is proposed to remove all the sampled SHs and keep the advantage of phase boost by using the multisampling control. The method is evaluated with a single-loop inverter-side current control, and its effectiveness is verified through the simulation and experiment.
KW - Control systems
KW - Harmonic analysis
KW - Modulation
KW - Multisampling
KW - Power harmonic filters
KW - Pulse width modulation
KW - Switches
KW - Switching frequency
KW - aliasing
KW - improved repetitive filter (IRF)
KW - low-order harmonics
KW - switching harmonics (SHs)
UR - http://www.scopus.com/inward/record.url?scp=85099583896&partnerID=8YFLogxK
U2 - 10.1109/JESTPE.2021.3050886
DO - 10.1109/JESTPE.2021.3050886
M3 - Journal article
SN - 2168-6777
VL - 10
SP - 2411
EP - 2423
JO - I E E E Journal of Emerging and Selected Topics in Power Electronics
JF - I E E E Journal of Emerging and Selected Topics in Power Electronics
IS - 2
M1 - 9319657
ER -