Line Voltage Sensorless Control of Grid-Connected Inverters Using Multisampling

Multisampling control provides an attractive way to improve the dynamics and stability of high-power three-phase grid-connected inverters. Beyond the desired performance in current control, more information can be acquired through multisampling. However, such an assumption is rarely discussed in grid-connected inverters. In order to fill this gap, a line voltage sensorless control scheme is proposed for LCL-filtered inverters. In this article, a multisampling is performed on the inverter-side current, and the linear regression of the multisampled current during zero vectors of inverter-modulation voltage is employed to estimate the filter capacitor voltage. Consequently, the cost of line voltage sensors is reduced and the failure of line voltage sensors is prevented when using multisampling current control. Furthermore, to address start-up transients, the line voltage can still be estimated by temporarily locking the upper arms of the inverter, and dc-link voltage can be precharged to the target value at the same time. Experimental results validate the effectiveness of the method on a down-scale inverter.