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A muti resonant controller for high-frequency-link single-phase inverter is proposed in this paper. An equivalent circuit, which behave just like conventional unipolar PWM inverter is proposed for the converter. The dynamic model of the inverter, which built in continuous domain, is built. The inverter has the advantages of high efficiency, high power density, low-cost, low noise, bidirectional power...
We propose a plug-and-play realization of the virtual infinite capacitor (VIC), which is an electronic circuit recently proposed in the literature for DC voltage filtering. The VIC is meant to replace large, expensive and unreliable electrolytic capacitors, and is mainly intended for applications where random fluctuations of the DC bus voltage may occur (i.e., the VIC is not tuned to one particular...
The aim of this paper is to explain a novel technique to improve voltage and frequency profiles on microgrids controlled using the droop control scheme. The method consists on retuning the controller according to the present load scenario by adjusting the droop coefficients in a way that is proportional to the load changes. The proposed technique is tested through numerical simulations and the results...
This paper presents a control strategy for a flexible single-phase microgrid that can operate in grid-connected or in islanded mode. The microgrid adopted is composed of two voltage source inverters (VSIs) operated in parallel and two local nonlinear loads. This approach is based on a hierarchical structure which consists of inner, primary and secondary levels. The inner control regulates the output...
This paper studies and compares control schemes for fully-integrated step-up dc-dc converters. The paper analyzes both a pulse-width-modulated and a pulse-frequency-modulated control schemes, and discusses the differences in terms of load currents and output voltages. Both control schemes were designed and simulated in a CMOS 65-nm technology. The paper also compares the analytic models to simulation...
Repetitive control (RC) scheme presents an attractive solution to achieve excellent steady-state tracking error and low total harmonic distortion (THD) for periodic signals. RC can produce extremely large gains at fundamental and each harmonic frequency of reference signal to achieve all harmonics suppression. However, a DC-AC inverter always has uneven THD distribution, e.g. THD concentrates at 4fc...
The aim of this study is to analyze and compare three droop controller schemes to regulate the operation of a microgrid. Three droop control schemes are selected because of their capability to regulate voltage, frequency and power sharing without using communication links and complex measurement systems. Specifically, the conventional droop controller and two of its variants are compared, the angular...
This manuscript presents modified scheme of synchronous space-vector modulation allowing providing nonlinear dependences between the fundamental voltage and fundamental frequency of dual three-phase open-winding ac drive with four modulated inverters. Behavior of the system with six control modes (characterized by different dc-voltages and switching frequencies of inverters) and two nonlinear Voltage/Frequency...
Materials of this paper show possibility of realization of any nonlinear dependences between voltage and frequency (nonlinear V/F (Volt/Hertz) dependences) of the open-loop six-phase drive on the base of four inverters, controlled by specialized algorithms of space-vector modulation. Specific continuous and discontinuous schemes of modulation allow providing in this case symmetry of the phase voltage...
In this paper the asymmetrical pulse width modulation (APWM) is proposed for the control of galvanically isolated impedance-source series resonant DC/DC converters in the buck mode. Contrary to the variable frequency control, which is most widespread control technique of the series resonant converters, the APWM features fixed frequency operation and reduced circulation energy of the converter. This...
High switching frequency is one of the effective methods to improve power density for a LLC resonant converter. However, conventional controllers such as a digital signal processor (DSP) and an analog controller have a performance of the limited frequency resolution which introduces high primary and secondary side current variations and poor output voltage regulation at high switching frequency. In...
A controller is proposed for a medium voltage medium frequency (MVMF) AC collection grid for utility scale Photovoltaic (PV) farms. A new MVMF AC collection grid was presented in previous work. It enhanced the system modularity, increased the system efficiency and reduced the passive component sizes. The MVMF AC collection grid comprises modules of inverter and medium frequency transformer that are...
For constant voltage constant frequency pulse-width modulation (PWM) inverter system, repetitive control (RC) can achieve zero steady-state tracking error for any periodic signal. Multi-rate repetitive control (MRC), which is featured by a fast system sampling rate and a reduced RC rate, is able to lower CPU computation load while achieving low tracking error and fast convergence speed. To accurately...
Energy technologies have a central role in social and economic development at all scales, from household and community to regional, national, and international. Among its welfare effects, energy is closely linked to environmental pollution and degradation, economic development, and quality of living. In this paper, we will give a look at important of distributed generation as an approach in integration...
This paper presents a new controller of a microgrid connected converter to reduce harmonic components to ensure high quality of electrical power, although the microgrid connected inverter with an LCL filter has the ability of attenuating the higher order harmonics. The major advantage of the proposed controller is that it can attenuate both the higher and lower order harmonics with a small size line...
Direct power control (DPC) and model predictive control (MPC) are two well known methods to achieve direct control of active power and reactive power in PWM rectifiers. They both select a voltage vector, according to a switching table or by minimizing a cost function, and then apply it in the next control period. The use of only one voltage vector during one control period leads to high power ripples...
A bi-frequency PFM controlled boost DC-DC converter is designed and implemented in this paper to improve the electro-magnetic interference (EMI) and efficiency of the system in a wide load range. The spectral energy of proposed bi-frequency PFM controlled converter is distributed to more frequency points to decrease the discrete harmonic peak, achieving low EMI. A control IC for the boost converter...
Flying capacitor multicell (FCM) converter is one of the well-known breeds of multilevel converters. There are several configurations of flying-capacitor-based converters presented and reviewed in the literature. One of the promising topologies of the FCM converter suitable for single/threephase applications requiring isolated converters is H-Bridge (Full-Bridge) FCM converter wherein two FCM converters...
This paper presents a control scheme for Static Compensators applied in distribution systems (DSTATCOM), that are used for regulation of voltage magnitude at point of common coupling (PCC) and it also has the function of eliminating harmonics of voltage through PCC-voltage-detection method. Voltage-magnitude regulation is accomplished through quadrature-current injection at PCC and harmonic mitigation...
The requirements of generating various low frequency voltage waveshapes are usually catered by using linear amplifiers, which results in low overall efficiency. High frequency voltage source inverters with low pass filter at the output are not suitable for these applications, as it is difficult to produce waveshapes containing high frequency components, and variation in frequency. A Boost Inverter...
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