Abstract
Active damping is a common way to stabilize the current control of LCL-filtered converters. In this paper, the stable region of −180º-phase-crossing is firstly identified within a predefined range of grid impedance and LCL parameter variations. Once the phase of the current control loop is in the identified region, a stabilization control can be attained. Subsequently, digital filters can be adopted to achieve active damping by reshaping the open-loop phase. Various digital filters are selected and benchmarked in this paper. It is confirmed that the all-pass filter has a unity gain and adjustable lagging phase before the Nyquist frequency, thereby being a promising solution to the phase reshaping. Therefore, the all-pass filter is employed to move the phase of the open-loop control (i.e., −180°-phase crossing) into the targeted region for active damping. Notably, the current controller and the all-pass filter-based active damping can be separately designed, indicating the easy implementation of the active damping. Experimental tests demonstrate that the proposed method can ensure the system stability over a wide range of parameter variations (e.g., grid impedance changes and LCL-filter parameter drifts) while maintaining fast dynamics with the grid-side current control.
Original language | English |
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Article number | 8758378 |
Journal | I E E E Transactions on Power Electronics |
Volume | 35 |
Issue number | 3 |
Pages (from-to) | 3114-3126 |
Number of pages | 13 |
ISSN | 0885-8993 |
DOIs | |
Publication status | Published - Mar 2020 |
Keywords
- All-pass filter
- Active damping
- LCL filter
- Digital control
- Parameter variations
- PWM converters
- parameter variations
- pulsewidth modulation (PWM) converters.
- digital control