A High-Gain Observer-Based Adaptive Super-Twisting Algorithm for DC-Link Voltage Control of NPC Converters

Abstract

Acting as an interface between the grid and many energy systems, the active front-end (AFE) has been widely used in a large variety of industrial applications. In this paper, in order to ensure the fast dynamic performance and good disturbance rejection ability of the AFE, a high-gain observer (HGO) plus adaptive super-twisting algorithm (STA) for the three-level neutral-point-clamped (NPC) converter is proposed. Comparing with the conventional PI control strategy, the proposed controller implements the adaptive STA in the voltage regulator to provide a faster transient response. The gains of the adaptive STA keep varying according to the rules being reduced in steady state but increasing in transient conditions. Therefore, the chattering phenomenon is mitigated and the dynamic response is guaranteed. Additionally, to undermine the impact of external disturbances on the dc-link voltage, a high-efficiency HGO is designed in the voltage regulation loop to reject it. Experimental results based on a three-level NPC prototype are given and compared with the conventional PI method to validate the fast dynamic performance and high disturbance rejection ability of the proposed approach.

Estimation‐Based Event‐Triggered Adaptive Terminal Sliding Mode Control without Pressure Sensors for a Polymer Electrolyte Membrane Fuel Cell Air Feeding System

“…Remark 6. [34,35] Under the assumption of the boundness of ψ(t), the error system (24) has the bounded-input boundedoutput stability. This implies that the estimation error E i (i = 1, 2, 3) of RHGO is uniformly ultimately bounded by appropriately adjusting the observation coefficient ε ro .…”

“…Remark 3. [34,35] Assume that ρ(t) is bounded as |ρ(t)| ≤ ρ 0 with ρ 0 > 0 being a unknown but finite positive constant, then for the error system (11), there exist a positive scalar χ > 0 and a finite time T 2 > 0 to ensure the boundedness and convergence of estimation errors, that is, jjz $ jj ≤ χðε, z $ ð0ÞÞ, ∀t > T 2 with z $ ¼ ½z 1 , z2 T .…”

“…To reduce the complexity of the observer, a nonlinear disturbance observer [21] and extended state observers [31][32][33] were effectively employed to estimation of cathode pressure and OER; however, the use of fixed observation gains is difficult to maintain a desired balance between antidisturbance ability and antinoise ability, which may not always guarantee satisfactory estimation accuracy over a wide operating range. Furthermore, the high gain observer (HGO) has been widely used to estimate unavailable variables in other engineering fields [34,35] due to less need for prior information about the controlled system, which is rarely mentioned in the field of PEM fuel cell. An additional concern is that from the perspective of practical applications, fewer sensors installed in the fuel cell system help to reduce the whole production costs.…”

Third-Order Sliding Mode Applied to the Direct Field-Oriented Control of the Asynchronous Generator for Variable-Speed Contra-Rotating Wind Turbine Generation Systems

“…Experimental results showed the characteristics of the STA technique in improving the response time of a six-phase motor. STA technique was proposed to control the DC-link of the NPC inverter [54]. Internal permanent-magnet synchronous motors (IPMSMs) were controlled by an adaptive STA observer [55].…”

Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments

“…High-gain observers have been considered to estimate the state in processes with nonlinear dynamics because they have robust estimation properties and disturbance rejection capabilities [ 34 , 35 , 36 , 37 , 38 ]. Regarding process control using HGOs, some works have been reported in literature.…”