Abstract
The double-frequency (2ω) power flows through the DC side of the single-phase quasi-Z-source inverter (QZSI) leads to the 2ω voltage ripple of capacitors and 2ω current ripple of inductors. This paper proposes a ripple vector cancellation modulation strategy (RVCMS) based on the thought of ripple vector cancellation. By analyzing the mechanism of ripple generation and transmission, we can obtain a variation of a shoot-through duty cycle to generate a compensated 2ω ripple used to cancel the 2ω current ripple of inductors caused by the 2ω ripple of DC link current, and the 2ω compensated variation of a shoot-through duty cycle with a specific amplitude and phase is added to the constant shoot-through duty cycle. Finally, simulation and experimental results demonstrate the correctness and effectiveness of the proposed modulation strategy for the single-phase QZSI.
Highlights
The single-phase quasi-Z-source inverter (QZSI) consists of two modules, a quasi-Z-source network, and an H-bridge, and the quasi-Z-source network includes two inductors, two capacitors, and a diode [1]
In [11], an active-filter-integrated single-phase QZSI was proposed: The active power filter (APF) consists of an extra switch leg and a second-order filter; the 2ω pulsating power of the AC load is transferred to the filter and the extra leg; the capacitor voltage and the inductor current in the DC side will no longer have the 2ω ripple component with this method, but an extra circuit means a higher cost and more complicated control
This paper mainly focuses on the suppression of the 2ω current ripple of inductors and proposes a new modulation strategy based on ripple vector cancellation
Summary
The single-phase quasi-Z-source inverter (QZSI) consists of two modules, a quasi-Z-source network, and an H-bridge, and the quasi-Z-source network includes two inductors, two capacitors, and a diode [1]. In [11], an active-filter-integrated single-phase QZSI was proposed: The APF consists of an extra switch leg and a second-order filter; the 2ω pulsating power of the AC load is transferred to the filter and the extra leg; the capacitor voltage and the inductor current in the DC side will no longer have the 2ω ripple component with this method, but an extra circuit means a higher cost and more complicated control. Reference [21] proposed a model-based current control approach based on the inherent relationship between the ripple component inductor and capacitor voltages in the DC side This approach can reduce the DC side inductor current ripple with active damping and constant virtual time for single-phase grid-tied QZSI with an LCL filter.
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