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A maximum efficiency control for a dual-motor drive system is presented in this paper. The torque sharing between two motors is optimized by using the perturbation and observation method. A fuzzy-logic controller is implemented for the perturbation and observation method. As a result, the step of perturbation can be adaptively modified to improve the performance. In addition, a simple calculation...
The differential-mode Ćuk inverter (DMCI), with outstanding features, has a good chance to replace the conventional topologies in grid connected application for renewable energies. Two modulation schemes have been introduced for the inverter in literature. Discontinuous-modulation scheme (DMS) uses one module in each half line cycle, whereas the continuous-modulation scheme (CMS) continuously uses...
The Maximum power point tracking (MPPT) algorithms are widely used in micro-inverters to maximize the PV panel's output power. The perturb and observe (P&O) algorithm is the most commonly used method due to its simple implementation. However, since the switching frequency of the BCM micro-inverter is variable, the switching duty ratio or the panel voltage could not be simply used as the perturbed...
In some cases it is unavoidable that part of the rooftop PV array is periodically shadowed by an adjacent object, greatly reducing yield. Usually, the time and amount of shadowing is known, and is considered as extra loss due to the location. Module Integrated Converter (MIC) systems are known to be a good solution for such cases, having the potential to increase the yield with as high as 25%, although...
The micro-converter Photovoltaic (PV) system which is composed of several cascaded Buck-Boost converters and a central inverter, enables each PV panel to operate at its local maximum power point (MPP). The cascaded buck-boost converter can operate in buck, boost or pass-through mode to realize a wide output voltage range without inverted polarity. However, there is a difficulty in keeping power balance...
Harvesting renewable energies is the solution to the global energy crisis. The performance of the grid-connected voltage source inverter (VSI) with an LCL-filter, used for renewable energy power conditioning, is dictated by the control technique used to regulate its output current. The closed-loop current control system is also responsible for providing active damping to damp the resonance introduced...
A controllable output impedance method for parallel inverters system is proposed in this paper. The control strategy uses LCL filter in output side and add a current loop to adjusting the output current of the inverter bridge. With this modification, the output impedance of inverter is compensated to a specific value then the difference of line and filter impedance can be neglected. Redesigned output...
This paper examines the issue of staying within the voltage capacity of a fixed bus voltage inverter during increasing magnetization state (MS) of variable flux permanent magnet synchronous machines (VF-PMSMs). MS manipulation using a fast stator id pulse is shown to induce a large voltage even at low speeds. In order to utilize the power conversion capability and improved efficiency regions of VF...
Hysteresis current control is an attractive nonlinear current control method for voltage source inverters when a fast system response is required. A well-known disadvantage of hysteresis current control is that the system has to operate over a wide switching frequency range. This causes an increase in the switching losses of the system and increases the difficulty in designing the output filter. The...
Through a case study in the secondary control of the droop-controlled inverter-based microgrid (MG), we illustrate the problem of distributed control subject to constraints on the control inputs. In order to eliminate the frequency deviation caused by the primary control while keeping the real and reactive power sharing property, the designed distributed controllers need to meet the requirement that...
In this work, a proof of concept prototype for a photovoltaic array emulator based on a DC-DC Boost converter is presented. This design arises from the need to study in the laboratory new PV inverters based on Silicon Carbide (SiC) devices in order to evaluate their performances. The lack of space for installation of real photovoltaic panels and the high costs of the commercial emulators lead to alternative...
In this paper, we present closed loop sampled-data linear quadratic regulator (LQR) based control scheme. Suggested scheme is applied on a practical linear system of a grid tie inverter for tracking a reference signal in the presence of external disturbance. LQR functions on the basis of minimization of a well-defined cost function. Prior knowledge about the external disturbance is utilized by the...
When paralleled inverters feed a common load, it is required that the load is shared according to their power ratings. In this paper, the robust droop controller (RDC) proposed in the literature for achieving accurate proportional power sharing for paralleled inverters is implemented in a way to ensure a bounded closed-loop performance. Using non-linear Lyapunov methods, it is shown that the controller...
An improved Trans-Z-Source Inverter (TZSI) shows advantages due to its high boost capability, which can overcome the mutual limitation between the shoot-through duty ratio and modulation index. This paper derives the state equations through analyzing the equivalent circuit of the TZSI, and then achieves the transfer functions through small signal analysis in detail. Based on the mathematical model,...
We propose a consensus-based distributed voltage control (DVC), which solves the problem of reactive power sharing in autonomous meshed inverter-based microgrids with inductive power lines. Opposed to other control strategies available thus far, the DVC does guarantee reactive power sharing in steady-state while only requiring distributed communication among inverters, i.e. no central computing nor...
This paper presents a robust control strategy for voltage controller of grid-connected inverter. The combining of feedback-feedforward control and ℋ− repetitive control is introduced to improve tracking performance and reduce the period disturbance. The achieved objective is robustly regulate voltage, good dynamic and tracking response. The proposed controller is tested in simulation by MATLAB/SIMULINK...
In recent years, the research on control strategy of three-phase grid-connected inverter has attracted significant attention. Proportion integration (PI) control method is widely utilized to control the grid-connected inverter. However, coordinate transformation is an essential and complex step during the design process of the conventional PI controller. It is difficult to implement in practice due...
Control techniques, applied to single-phase two-stage grid-connected photovoltaic (PV) systems, mainly achieve functions of maximum power point tracking (MPPT), voltage adjustment at inverter DC-link, and grid current control. Conventional control techniques require measurements of PV voltage and current, DC-link voltage, and grid voltage and current. Commonly, sensorless techniques are proposed to...
This paper aims to study the recent work regarding the maximum power point tracker (MPPT) based on a sliding-mode manner for a PV array. Such a MPPT accompanies a perturbation and observation algorithm as well as a boost converter. Moreover, it needs a straight sliding-line and some adjustments on its location until a PV characteristic curve and this sliding line cross each other at the maximum power...
This article presents a detailed three-phase grid connected PV model which includes important control systems required for EMT-type simulation. A one diode model for the PV array is used to simulate environmental constraints such as solar irradiation. A detailed control system including dc voltage control, inner current control, MPPT and PWM control are implemented in order to simulate the model during...
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