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This paper introduces a new insertion index selection method to control a Back-to-Back Modular Multilevel Converter (MMC) laboratory platform. The test bench is based on a Power-Hardware-In-the-Loop (PHIL) setup constructed from two 6kVA, 3-phase, 10 cells per arm MMC systems connected in Back-to-Back configuration. The proposed insertion index selection method uses the arithmetic mean of available...
Reliability is one of the key features that is sought after in converter design. Electrolytic capacitors are the most common capacitor type in switching mode power supplies to be used as a DC bus energy storage. However, electrolytic capacitors are known to degrade due to aging. This paper introduces a capacitance degradation detection method for a step-down DC-DC converter that is based on introducing...
Whereas bipolar DC microgrid has several advantages over monopolar DC grid [1], [2], its disadvantages cannot be underestimated. The currents in the pole lines can become asymmetric, and the neutral conductor carries non-zero current. To eliminate the current imbalance caused by unipolar loads/generators in bipolar DC microgrids, different types of current redistributor have been proposed and implemented...
The superior harmonic performance of the modular multilevel converter facilitates reduction in passive filtering requirements. However, in practice, any volume and weight reduction brought about by using smaller filtering components, is offset by the increase in stored capacitor energy inside the converter. This paper proposes injection of high-frequency circulating currents and zero-sequence voltages,...
Light-emitting-diodes (LEDs) are solid-state devices with specific v-i characteristics. In this paper we study the basic requirement of the driving circuits and discuss the proper approach to driving LEDs from the circuit theoretic viewpoint. We compare voltage source driving and current source driving, and discuss their relative advantages and constraints. We specifically introduce the use of duality...
This paper proposes a DC-DC converter for ultra-low power battery management. The proposed circuit consists of a switched capacitor converter (SCC) and self-biased linear regulator (SBLR). The SBLR monitors an output load current and controls the switching frequency of the SCC to achieve both ultra-low stand-by power and wide load current capability. Measurement results demonstrated that the converter...
The complete inrush current elimination depends on the veracity of the residual flux prediction for transformers. The precedent methods cannot satisfy the increasingly strict engineering requirements. Considering the chopping current and shunt capacitor influence on residual flux, a method for predicting residual flux based on the dynamic Jiles Atherton hysteresis model is proposed in this paper by...
This paper deals with the observability analysis and the observer design for the multicellular converter by taking into account its hybrid behavior. Firstly, we study the observability by using the recent results of the geometric approach, this study provides a simple necessary and sufficient condition of the observability of the converter for a given switching sequence. Secondly, we show the gathering...
Series of commissioning tests are needed before UHV transmission system putting into operation. In this paper, with the characteristics of Huainan-Shanghai 1000kV transmission system, electromagnetic transient simulation results and experimental data portion commissioning tests were compared and analyzed. Three typical experiments were studied, including the switching capacitor of low-voltage side...
Grid connected Voltage Source Converters (VSCs) with LCL filters usually have voltage measurements at the filter capacitors, while it can be important to control the active or reactive power injection at the grid-side of the LCL filter, for instance at a Point of Common Coupling (PCC). Synchronization to the PCC voltage can be obtained by Virtual Flux (VF) estimation, which can also allow for voltage...
In this paper we present the realisation of an HVDC experimental platform with modular multilevel converter and two-level voltage source converter. Local control strategies for both converters are outlined in detail. The experimental platform is configured in such a way that the power-flow is controlled by the modular multilevel converter, while the DC voltage is regulated by the two-level voltage...
A DC-link capacitance estimation method is presented for a three-phase voltage-source converter. The measured phase currents and DC-link voltage of the converter are used in formulation of the input and output signals for the estimator. The estimator is based on the ordinary least squares method. The capacitance can be estimated during the startup of the converter or while the converter is in normal...
An efficient three phase interleaved DC-DC converter is proposed with inductor current and voltage control. The use of multiple sensors for each phase current is eliminated using current reconstruction. This reduces the number of current sensors and improves the reliability. The inductor current control is achieved using single current sensor which measures DC-link current. The proposed converter...
The complexity of power systems and the change of demand load at the consumer make it necessary to control the voltage to avoid any unnecessary voltage drop beyond the limits allowed within the international standards and achieve optimum energy efficiency. This paper introduces a simple method that can regulate the voltage of a system without the sophisticated electronic devices. The method that controls...
This paper aims to focus on the smooth output of Buck converters under the input perturbations and load disturbances using the high-order sliding mode controller with a differentiator (HOSMD) based on the only measurement of output voltage. Theoretical analysis and design procedures of the controller designed by prescribed control law, one of the high-order sliding modes, are presented in detail....
In microgrid systems one or more inverters should be grid-forming in order to control the voltage during island mode operation. Usually the voltage regulation is operated controlling the capacitor voltage of the LCL filter interconnected between the converter and the load. In the present paper a cascade control is proposed for a Three-Level Neutral Point Clamped (3L-NPC) inverter where the voltage...
In this paper a new voltage measurement technique for modular multilevel converter (MMC) capacitors is proposed. While all the capacitors voltages should be known for closed loop control of MMCs, only the arms voltages are measured employing the proposed method. Therefore, the number of voltage sensors reduced dramatically to one per arm. The capacitors voltage quantities are updated continuously...
This paper proposes a novel integrated light-emitting diodes (LEDs) driver with power-factor correction (PFC), suitable for streetlighting applications. The presented LED driver integrates a buck-boost converter with a flyback converter into a single-stage conversion circuit topology. The inductor inside the buck-boost-type sub-circuit is designed to operate in discontinuous-conduction mode (DCM)...
The Modular Multilevel Converter (MMC) control presents more technical challenges than the regular 2-level Voltage Sourced Converters (VSC) one. One of the most common type of control investigaded in literature is based on techniques such as the Phase Opposite Disposition PWM (POD-PWM), which include balancing capacitor voltages and circulating current control. This paper presents some details that...
This paper presents a Two-Switch Forward Converter (2SFC) designed to charge small arrays of battery cells. Such battery charger can be used to analyze the influence of different charge profiles on batteries and on their indicators, like in State Of Health (SOH) and State Of Charge (SOC) ones, beyond of in active balancing studies. The main design steps for the 2SFC will be presented along with the...
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