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The modular multilevel converters (MMC) has become an attractive research subject of power electronics due to its special topology. In this paper, a novel sub-module circuit for the MMC is proposed. Compared with the traditional sub-module circuits, the number of power semiconductors used in the proposed circuit is reduced by a quarter. Then, an improved three-phase multilevel topology is also constructed...
A novel sub-module circuit is proposed in this paper based on the controllability theory. At first, traditional full bridge sub-modules (FBSM) of the MMC is modeled as a switched linear system, then controllability of the switched linear system model of the sub-module circuit is studied. It is found that the sub-module circuit is state controllable with only four operation modes adopted in the model...
This paper presents a full-order equivalent circuit model of Dual Active Bridge (DAB) converter. The proposed equivalent circuit facilitates the in-depth knowledge on the physical insight of DAB converter and can precisely retain both the steady state and dynamic behavior of the original system. This equivalent circuit can be divided into two parts: ac branch and dc branch. Both ac branch and dc branch...
In three-phase dual-active-bridge (DAB) converter, the zero-voltage-switching (ZVS) range, DC capacitor ripple current and converter efficiency are significantly impacted by the selectable system parameters, including transformer turn ratio n, switching frequency f and leakage inductance Lk. The converter performance also varies with different operation conditions, i.e., input voltage, output voltage...
Due to nonlinearity and uncertainty of induction cooker system, it is difficult to establish an accurate mathematical model for control purpose. This paper proposes an appropriate fuzzy control strategy for controlling pan temperature of induction cooker system, without an accurate control model. In induction cooker system, the temperature feedback is from the glass countertop instead of the pan....
Cascaded multilevel inverter (MLI) topologies have received an attractive solution for grid connected PV system. In this paper, two-cascaded MLI topologies are presented for grid connected PV system. These are seven level cascaded H-bridge multilevel inverter and three phase cascaded voltage source multilevel inverter. In both presented MLI configurations, each PV module is connected to one DC-DC...
Dead-time effect of dual active bridge (DAB) DC-DC converter is usually out of consideration in traditional optimized strategies, causing the deviation of the theoretical and actual results. In this paper, the current stress model of DAB with dead-time effect is given, and combining the transmission power model, a current-stress-optimized strategy is proposed. Meanwhile, the corresponding control...
H-bridge cascaded inverter can be used for harmonic compensation in medium and high voltage systems. As the equivalent switching frequency is high, L-type filter is commonly used for H-bridge cascaded inverter. Meanwhile, considering device safety and filtering effect, inductance value of L filter is large. When the command current contains harmonics, especially high harmonics, large connecting inductance...
As the fluctuation of sub-module capacitance voltage when MMC operates at low frequency, the application of MMC in the field of motor drive has been limited. Therefore, this paper proposes a low frequency control method for the MMC with tuned filter circuit. Based on the theoretical analysis for this tuned filter, the circulating current of 2nd frequency could be suppressed effectively at rated frequency...
This paper compares some performances of a six-phase switched reluctance motor (SRM) using asymmetrical half bridge (AHB) converter and m-switch converter. The topologies and characteristics of the two converters are firstly analyzed. The steady-state torque, current and voltage waveforms of SRM using the two converters are performed and compared under the same operation conditions. Simulation results...
This paper presents the influence of switching frequency on the dual active bridge (DAB) dc-dc converter on the power transmission characteristics and the soft switching realization. Based on this, a switching frequency optimization of dual phase shift control is proposed to realize ZVS over the whole load range. It is an optimization of the PWM plus phase-shift control, which can reduce switching...
Multilevel converters are an emerging industrial technology and are the subject of a substantial amount of research. However, they are yet to find their way into many mainstream engineering applications. This paper presents a method of quantifying the benefits and disadvantages of multilevel converters of increasing order. The analysis focuses on the cascaded H-bride topology for grid-tie battery...
This paper presents a novel method for fault detection and location in modular five-level converters (MFLC) based on stacked sparse autoencoder (SSAE). SSAE is composed of multiple SAE and a softmax classifier. The capacitor voltage signals of all sub-modules (SMs) in the MFLC circuit are combined into a multi-channel signal. By moving window along the multi-channel signal, a set of signal segments...
An optimized modulation based on model predictive control for current-fed dual active bridge converter achieving high efficiency in wide load range is proposed in this paper. The low voltage side switches can realize zero current switching by secondary clamping technique. The pulse width modulation of secondary side switches is encoded with instantaneous power. When in light load, the turn-on moment...
Grid connected PV systems are the most popular solar electric system on the market today. The most important device in the grid-connected PV system is the inverter. This paper presents a survey on the grid connected PV inverters and the system topologies used for grid connected PV system. The review describes different two level inverter topologies as well as multilevel inverter topologies. Cascaded...
The active-forced-commutated (AFC) bridge for high-voltage (HV) DC transmission has recently been proposed, which operates low-loss thyristor valves in the manner of a voltage source converter (VSC) with the assistance of a self-commutated full-bridge (FB) chain-link (CL) circuit, creating a hybrid VSC solution which retains the key advantage of high-efficiency performance found in conventional line-commutated-converters...
A novel topology is proposed that interfaces between one or multiple DC sources and a three-phase machine. The DC-side converter consists of two half-bridges that form a specialized converter. The half-bridges operate at a reduced voltage which reduces inductor effort and switching losses. The resulting four DC-link levels power two three-phase bridges that can drive open-winding machines. The circuit...
As the development and building of 220kV and 500kV Unified Power Flow Controller (UPFC) in Jiangsu grid of China, a higher requirement is put forward by power grid analysis on the accuracy of modelling and simulation. UPFC has different characteristics under different control strategies, and Modular Multilevel Converters (MMC) simulation is a difficult task. In order to study its dynamic characteristics,...
This paper describes the analysis of a Dual Active Bridge converter (DAB) with soft switching and the minimum RMS current for the whole power range, using Triple Phase Shift (TPS) modulation. This analysis shows the conditions needed to have zero voltage switching (ZVS) and zero current switching (ZCS), furthermore the minimum RMS current, for all output power range. The validation has been done by...
This paper presents a case study of different control approaches for a single phase Dual Active Bridge (DAB) based MVDC Shipboard power system (SPS). The Line Regulating Converters (LRCs) are based on DAB topology and the load side converters or Point of Load Converters (POLs) are based on buck topology. The tightly controlled POLs exhibit a constant power load (CPL) behaviour, which has a destabilising...
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