Digital Controller Design Based on Active Damping Method of Capacitor Current Feedback for Auxiliary Resonant Snubber Inverter with LC Filter

Abstract

Abstract:In some high-performance applications, an LC filter must be added to the auxiliary resonant snubber inverter (ARSI) to reduce the output current ripple. However, resonance occurs due to the additional LC filter, which makes the traditional closed-loop control not suitable to be used directly. Therefore, this paper presents a double-loop digital control based on the active damping method of capacitor current feedback to stabilize the system. Most of the studies on active damping methods are focused on the grid in consideration of zero resistance. However, the load resistance should not be neglected in the drive system. Therefore, the load resistance and digital control delays are considered in this paper. Moreover, an improved loading method is proposed to improve the duty ratio range. In order to verify the effectiveness of the controller, a prototype was developed. The simulation and experimental results demonstrate that soft-switching can be realized for the entire load range. The maximum duty ratio is improved by 0.01 by using the proposed loading method. The resonance can be eliminated by using the proposed control method.

Solar Powered Unmanned Aerial Vehicle With Active Output Filter Under Non-Linear Load Conditions

“…Fig. 3 (b) shows the proposed closed-loop control strategy for AOF to produce an active compensation resistance technique, which is used widely in energy conversion control systems [30]. The closed-loop control strategy provides a resistance emulator in series with the H-bridge topology which creates a voltage injection across it to dampen the undesirable harmonics generated from the AOF.…”

“…Conversely, reducing the switching frequency requires bulky passive LC output filters to provide a sinusoidal load output voltage [24]. Challenges to use the active filtration techniques by voltage or current injection have been made since the 1970's to reduce the use of passive filters [30]. In particular, series active filters are capable to suppress voltage harmonics generated by the load or source especially with aggressive deployment in inverter system into electrical vehicles with renewable energy systems [31][32][33].…”

Low-Loss Active Grid Impedance Cancellation in Grid-Connected Inverters with LCL Filter

“…The passive damping method acts on the LCL filter by inserting the impedance around the filter resonant frequencies at the expense of additional power loss and degradation of filtering attenuation [3][4][5]. The active damping (AD) approach is to integrate the damping function into the inverter control so that the inverter equivalent output impedance around the filter resonant frequencies or over the frequency range is increased [2,[6][7][8][9][10][11][12][13]. Among them, active damping methods are preferred because no additional power consuming resistor is required.…”