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In this paper, a variable dc bus control strategy is evaluated for a bidirectional grid connected electric vehicle (EV) charger topology. The EV charger under consideration comprises of an ac-dc 3-φ active rectifier stage followed by a dc-dc dual active bridge (DAB) converter. The voltage of the common dc-link between the ac-dc stage and the dc-dc stage is regulated such that it follows the voltage...
With the steady transition towards a more dominant decentralized power generation and the further reduction of conventional fossil fuel-based power plants, future utility grids require higher demands regarding voltage quality and supply reliability. Active power filters with energy storage capability, here referred to as Power Conditioning Systems (PCS), offer grid supporting and stabilizing measures...
In this paper, constrained model predictive control (MPC) based on parallel neural network optimization is proposed to apply to pulse width modulation (PWM) rectifier and improve power quality. An decoupled model of three-phase rectifier in abc coordinates is built. Then, the constrained MPC method is proposed. This method breaks the limits of predictive control with finite set and without constraints...
Droop control is widely used in distributed generators for relating their terminal parameters to power generation. These generators are usually assumed to have enough capacities for supplying the required power. This is however not always true, especially with renewable sources with no or insufficient storage. To deal with this issue, an improved droop-based control is proposed for single-phase two-stage...
This paper discusses the active and reactive power control method for a modular multilevel converter (MMC) based grid-connected PV system. The voltage vector space analysis is performed by using average value models for the feasibility analysis of reactive power compensation (RPC). The proposed double-loop control strategy enables the PV system to handle unidirectional active power flow and bidirectional...
Voltage deviations of dc-link capacitors are the main problem of multilevel diode-clamped converters (DCC). In this paper, a novel carrier-based voltage balance method is proposed to balance the dc-link capacitors of five-level DCCs. The proposed method is characterized by injecting proper zero-sequence voltages in the modulation signals of carrier-based modulators. The effects of the injected zero-sequence...
This paper proposes a single-phase ac-dc-ac converter composed of two three-leg converters connected in series with an H-bridge on its grid side. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental overvoltage...
Single-phase grid-connected inverters with LCL filter are widely used to connect photovoltaic systems to the utility grid. Among the existing control schemes, predictive control methods are faster and more accurate but also more complicated to implement. Recently, the Model Predictive Control (MPC) algorithm for single-phase inverter has been presented, where the algorithm implementation is straightforward...
This paper proposes the improved topology and control strategy of three-phase cascaded bridgeless rectifier (CBR) suitable to serve as the rectifier stage for a medium/high voltage multilevel converter. Compared with traditional H-bridge based multilevel rectifiers, the proposed topology adopts much fewer fully-controlled devices, which greatly reduces the control complexity, thus increasing the system...
This paper presents a new four-quadrant bridgeless boost type rectifier with the use of Active Virtual Ground (AVG) technology. The presented topology can step up the AC grid voltage to a regulated DC voltage under a stable bidirectional current flow with real power or reactive power delivery. By using bridgeless rectifier configuration and 3-level switching method, only two high frequency switches...
Recent design trends for induction heating appliances are leading to higher power burners that offer unprecedented performance levels to the user. However, this evolution is usually constrained by the maximum power that can be drained from the mains, which is usually limited by the maximum current per phase. To overcome this limitation, the design of multi-phase converters is tackled to increase the...
Using the conventional look-up table-direct power control (LUT-DPC) strategy with its two-level hysteresis comparators and conventional switching table, poor regulation of active power (abnormal fluctuations appeared in reactive power waveform), non-sinusoidal input currents with a little high THD and depressed power factor are obtained. This study therefore set out to solve these problems; the conventional...
A novel virtual voltage control strategy is proposed for modular multilevel converter in order to reduce the quantity of voltage sensors at the terminal. The output voltage of the inverter is obtained through the upper and lower arm currents of the converter and used to trace the reference active and reactive power, respectively. According to the Routh-Hurwitz criterion, the root trajectory of the...
In this paper, a predictive direct power control (P-DPC) strategy for a three level NPC rectifier under ideal grid voltage is proposed, discussed and applied. With the proposed P-DPC strategy, the control targets are the active power, the reactive power and the neutral potential voltage; neither hysteresis comparators nor switching table are needed; sinusoidal input current with low total harmonic...
Although the mechanism of electric energy flow for nonsinusoidal conditions is well described today, so fare is not yet available a generalized power theory, and theoretical calculations for the design of such devices as active filters or dynamic compensators. Therefore the task of designing compensators for optimize energy transmission with nonlinear time-varying loads in nonsinusoidal regimes is,...
This paper introduces a new power factor correction scheme for a flyback converter with primary regulation technique, to ideally eliminate the distortion of the ac input current (practically a Total Harmonic Distortion (THD) lower than 5%). The effectiveness of the new control scheme is proved in a 35W driver with universal input range (90VAC∼277VAC). Application target is Solid State Lighting (LED...
Many utilities may prefer that various distributed generation (DG) systems, particularly photovoltaic (PV) systems in this study, connected to their network are able to maintain a fixed power factor or higher (e.g., unity power factor) as a current source. On the contrary, some utilities may require that such a DG system participates in controlling reactive power for regulating voltage. Furthermore,...
In this paper, a new DC ice-melting scheme based on hybrid modular multilevel converter (MMC) is proposed considering the problems of existing DC ice-melting device, such as high harmonic content, complicated mode switching operation, large size and so on. In the scheme, a novel structure of MMC is composed of the upper bridge arm all using full bridge sub-module (FBSM) and the lower bridge arm all...
The paper proposes a moving average filter (MAF)-based model predictive control (MPC) for the electric vehicles (EVs) bidirectional chargers. Grid virtual flux is used to estimate the grid voltage through a low pass filter (LPF). An MAF, which acts as an ideal LPF, can eliminate the effect of unbalanced/distorted grid voltage and unknown characteristic harmonics. Both the two-cascaded LPF-based and...
A neutral point voltage feedback control strategy based on double modulation waves carrier-based PWM for three level converters is proposed in this paper. Using this strategy, neutral point voltage can be adjusted at will, output AC current can be guaranteed no distortion caused by imbalanced neutral point voltage, and the neutral point fluctuation can be eliminated completely. The strategy is suitable...
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