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This paper proposed a novel flying-capacitor-clamped five-level inverter based on bridge modular switched-capacitor topology. The inverter features the switched-capacitor circuit with step-up ability and the multilevel inverter circuit with flying-capacitor-clamped performance. With the composite structure, the number of components is cut down compared with the topology of conventional multilevel...
The matrix converter is an AC-to-AC direct power conversion system that can generate variable voltage variable frequency output. There is a topology of Matrix converter having sinusoidal waveforms using output LC filter. It enabled that to provide lower EMI, lower common-mode current, and lower shaft voltage. However, there are some problems that filter size become bulky because of the restriction...
This paper presents a Multi-Phase Sliding Mode(MPSM) Control Strategy for solving chattering issues inherently existing in DC-DC converters. The main idea of the proposed methodology is to implement a MPSM Control for geometrically nullifying the amplitude of ripple currents yielded by the switching patterns. The benefits of the proposed Multi-Phase Sliding Mode Control strategy involve low-switching...
The controller design for wind energy conversion systems (WECS) is complicated considering the highly nonlinear properties of electric machines and power converters. Targeting at a controller for WECS, this article adopts a passivity-based PI control (PI-PBC) method, to which the stability can be analytically guaranteed. Then, a comparative study between the proposed method and a standard PI is provided...
The complete design of the current control loop for single-phase inverters connected to weak grids is presented. The problems associated to the design of current control loop when highly distorted grid voltages are present and LCL filters are used to couple the inverters to the grid, are analyzed. Fourier coefficients decomposition is used to obtain an ahead-of-time version for the nonideal voltage...
Models of converters based on averaging have been used widely with numerous benefits. Multifrequency averaging (MFA) model can predict both the fundamental and switching behavior of converters and has the faster simulation run times associated with average-value models. Third harmonic injection is commonly used in the modulation signal for three-phase inverters to increase the inverter maximum output...
The MMC operated in Current Source Mode (CSM) with branch current control shows excellent fault limiting capability. With proper design, the same capability is achieved in Voltage Source Mode (VSM). The key is combining the VSM and CSM controls and having same state variables. Seamless transition between CSM and VSM is ensured by the change of references triggered either by the user or by internal...
The distributed inverters are integrated into grid without coordinated PWM and the switching ripples of inverters are randomly accumulated at point of common coupling (PCC). Global synchronous pulse width modulation (GSPWM) can attenuate the accumulated switching ripples. This paper proposes time compensation method which compensates the time delay of synchronization signals for inverters in distance...
This paper proposed a modified pulse energy modulation (PEM) technique for a single-phase single-stage three-switch buck-boost inverter, solving the issue existed in practical applications that the requirement for sampling circuits is too high to achieve. The three-switch buck-boost inverter was investigated for both standalone and grid-connected operations. Simulation and experimental results verified...
As electrolytic capacitor is apt to fail in power system, it is very important to monitor its ESR and C. A novel online monitoring method of capacitor's ESR and C for DCM Flyback Converter is proposed in this paper. Based on the ac component of capacitor voltage, the calculation model is founded. The method needs no current sensor and is effective for the converter operating at any switching frequency...
This paper proposes a parallel-connected system where two three-phase three-level T-Type photovoltaic inverters with common ac and dc sides to improve the power rating. However, zero-sequence circulating currents (ZSCCs) will occur, which will distort currents, decrease efficiency, and increase loss. In this paper, the fundamental mechanism of ZSCCs based on the derived model of ZSCCs is analyzed...
Circulating current has been the major concern for the implementing of paralleled converters. Extensive studies have been conducted in reducing the circulating current with different modulation strategies. However existing methods are either suffering from poor performances or too complicated for implementation. This paper proposes an interleaved carrier phase-shift (ICPS) PWM to reduce the peak value...
Digital control system usually introduces a beat of delay, which includes PWM upload delay and zero-order holder delay. The delay not only reduces the system phase margin, but also changes the impedance characteristics of active damping, which influences the system minimum phase property and threatens the stability of the injected current. In this paper, a PWM real-time upload method and the detailed...
This paper proposes a permanent magnet (PM) machine position sensorless drive for high speed (>10-krpm) applications. A fully discretized back electromotive force (EMF) estimator is designed to overcome several high speed rotor position estimation issues, including the voltage error due to pulse-width-modulation (PWM), dq inductance cross-coupling effect and the deviation between the estimated...
This paper presents a carrier-based modulation strategy for 3×1-modular matrix converters (MC) to achieve zero common mode voltage (CMV). A geometric method is introduced to determine the range of the modulation signals. Due to the nonzero CMV during the commutation time with the traditional four-step current-based commutation method, a modified four-step current-based commutation method is presented...
For the cost reduction of the inverter system, a DC link shunt resistor can be used to obtain the phase current of the AC motor. However, the phase current cannot be obtained from the shunt resistor when the duration of the active vector is shorter than the minimum time to sample the DC link current accurately. Conventional methods to reconstruct the phase current have some problems such as the high...
This paper evaluates the capability, compatibility, and usability of Hardware-in-the-Loop platforms for DC-DC converter. This was accomplished by interfacing the platforms with a physical power stage as well as a controller. The employed platforms are Hi-Rel Power-pole board, Texas Instruments Digital Controller, RTDS, OPAL-RT, dSPACE, and Typhoon. Two sets of experimentation were performed: the power...
This paper proposes a PWM method reducing harmonics of two interleaved converters at twice the switching frequency region. If harmonics at twice the switching frequency region can be reduced by the PWM method, the size of filter interfacing the grid and converter would be reduced. Based on Fourier series of phase voltage in every switching period, offset voltage for PWM minimizing harmonics at twice...
In this paper, a method of optimizing efficiency of hybrid photovoltaic-grid power system by changing dc bus voltage is introduced. The hybrid photovoltaic-grid power system composed of a solar cell, grid, DC bus, solar cell interface converter (Boost + full-bridge LLC resonant converter), grid interface converter (single-phase PWM rectifier) and load interface converter (half-bridge LLC resonant...
According to the control requirements of modular power used in energy storage systems, a parallel control strategy for bi-directional DC-DC converter is proposed and applied to the bi-directional DC-DC converter combined by current-fed half bridge and voltage-fed half bridge. While converters operate in parallel, the master-slave control based on digital communications can solve the problem of unequal...
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