Tracking Control for a DC Microgrid Feeding Uncertain Loads in More Electric Aircraft: Adaptive Backstepping Approach

Abstract

More electric aircrafts (MEAs) comprise a vast amount of power electronic loads, which usually behave as constant power loads (CPLs). The incremental negative impedance of CPLs threatens system stability. To ensure an effective control of power flow in MEAs, eliminating the undesired behavior of CPLs is a necessity. This aim requires spontaneous power estimation of the time-varying uncertain loads. In this paper, an adaptive backstepping controller, which is interconnected to a 3 rd degree cubature Kalman filter (CKF), is developed for a DC MG feeding non-ideal CPLs. At first, the load power is considered as an artificial state and augmented into the system states, which enables estimation of not only the DC MG states but also the unknown value of the load power. The estimated load power is then forwarded to a backstepping controller. The systematic approach of this controller allows obtaining the control signal, which is the duty ratio of the switch, to not only system stabilizing but also tracking a desired voltage of the DC bus under the load power variations. The proposed adaptive controller is tested on a DC MG that has one CPL. The conducted experimental results verify the proposed nonlinear control in tracking the desired voltage of the DC bus under slow and fast variations of the load power.Index Terms-More electric aircraft power system, DC microgrid (MG), Constant power load (CPL), Cubature Kalman filter (CKF), Adaptive backstepping controller.

Tracking Control for Hydrogen Fuel Cell Systems in Zero‐Emission Ferry Ships

“…e primary control objective is to manipulate the DC/DC boost converter that stabilizes the voltage of the DC bus V CPL toward its desired value V ref . e control signal is then used to generate pulse-width modulation (PWM) gate signals for the converter [32]. Moreover, the secondary goal is to manipulate the fuel cell generator to provide the power to the loads.…”

“…Here, since only CPLs are considered, the total power demand will be the net sum of the instantaneous CPL power. Without loss of generality, consider one CPL with the power level P CPL and the one resistive load R. us, the current should track the reference [32] Figure 2: Circuit diagram of the marine DC MG with a fuel cell and a CPL.…”

“…ese dynamics are not in the form of the conventional strict-feedback forms as the virtual inputs P H 2 and P O 2 are not affine in (2) and the overall dynamics comprise three control inputs. So, the conventional backstepping design procedure [32] is not applicable. However, in this paper, such difficulties are handled by (i) defining the tracking error e 3 as a nonlinear function of the virtual inputs, (ii) splitting the overall design procedure into two parts, and (iii) introducing an additional time-varying reference for the current of the fuel cell based on the properties of the nonlinear DC MG. ese are the main distinctive features of the proposed approach over the existing backstepping techniques.…”

A Hybrid Predictive Control for a Current Source Converter in an Aircraft DC Microgrid

“…where x[n] denotes the value of variable x at the beginning of the nth sampling period. Note that the sampling time is T so for Equation (5). For the load voltage model, the only controllable variable is the output current i o .…”

“…The onboard power system is a typical microgrid (MG) system with distributed supplies and loads [2]. The DC MG has been widely considered as a preferable solution for the future onboard MG and has garnered great attention [3][4][5]. A typical paradigm of the DC MG is shown in Figure 1.…”