A Novel Sliding Mode Control Technique for Indirect Current Controlled Active Power Filter

Abstract

A novel sliding mode control (SMC) method for indirect current controlled three-phase parallel active power filter is presented in this paper. There are two designed closed loops in the system: one is the DC voltage controlling loop and the other is the reference current tracking loop. The first loop with a PI regulator is used to control the DC voltage approximating to the given voltage of capacitor, and the output of PI regulator through a low-pass filter is applied as the input of the power supply reference currents. The second loop implements the tracking of the reference currents using integral sliding mode controller, which can improve the harmonic treating performance. Compared with the direct current control technique, it is convenient to be implemented with digital signal processing system because of simpler system structure and better harmonic treating property. Simulation results verify that the generated reference currents have the same amplitude with the load currents, demonstrating the superior harmonic compensating effects with the proposed shunt active power filter compared with the hysteresis method.

A Refined Self-Tuning Filter-Based Instantaneous Power Theory Algorithm for Indirect Current Controlled Three-Level Inverter-Based Shunt Active Power Filters under Non-sinusoidal Source Voltage Conditions

“…In other words, it changes the DCC-based operation to ICC-based operation. Unlike DCC-based operation, ICC-based operation which has been reported in [43][44][45]47] to possess exact information on switching ripples existing in the source current, allows accurate generation of reference currents to continuously control the operation of the SAPF and thus eliminates any unnecessary problem caused by SAPF switching operations.…”

“…To date, the conventional STF-pq theory algorithm still produces a non-sinusoidal reference current [7,40,42] and thus forces the SAPF to operate based on a direct current controlled (DCC) scheme [43][44][45]. From previous literature [45][46][47], it is revealed that the SAPF switching operation produces switching ripples which potentially degrade the THD value of the mitigated source current.…”

“…From previous literature [45][46][47], it is revealed that the SAPF switching operation produces switching ripples which potentially degrade the THD value of the mitigated source current. However, the DCC scheme which generates pulse-width modulation (PWM) switching pulses based on error signals resulting from the difference between the measured injection current and its non-sinusoidal reference current counterpart [43][44][45], does not possess accurate information on the characteristics of the actual source current. Therefore, even if the source current is contaminated by switching ripples, DCC scheme is unable to alleviate the problems due to a lack of exact information.…”

“…As a result, a mitigated source current of higher THD value is produced. Although the indirect current controlled (ICC) scheme which generates PWM switching pulses based on error signals resulting from the difference between the actual source current and its sinusoidal reference current counterpart [2,22,43,44] has been proven to overcome this weakness of the DCC scheme, there is still no work on STF-pq theory which has been conducted together with ICC scheme. In fact, the working principle of the conventional STF-pq theory algorithm has limited its application to DCC schemes.…”

A Simplified Synchronous Reference Frame for Indirect Current Controlled Three-level Inverter-based Shunt Active Power Filters

“…To date, the conventional SRF algorithm is still producing a non-sinusoidal reference current through a derivation of the extracted harmonic current, and forcing the switching signals meant for controlling the switching activities of the SAPF to be generated based on the direct current controlled (DCC) scheme [30]- [32].…”