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Existing control strategies of modular multilevel converter (MMC) have many drawbacks, such as need of several parameter controllers, complex parameter tuning and huge computational burden. This paper proposes a novel control method based on the hybrid architecture of proportional integral (PI) control and model predictive control (MPC). The PI controller is used as external controllers to control...
A control strategy of three-level multi-functional grid-connected inverter for distributed grid is proposed. According to different conditions of distributed generation, the multi-functional inverter can realize the function of injecting power from the distributed generation and suppling power into the grid simultaneously or separately, and the function of shunt active power filters such as the harmonic...
This paper presents an improved model predictive control strategy with fixed switching frequency. The proposed method adds four virtual voltage vectors to the four real voltage vectors of the conventional finite control set model predictive control to reduce the harmonic content of the grid current and uses a modulator to realize fixed switching frequency. Furthermore, a novel cost function, which...
Performance analysis and output voltage regulation of a cascaded step-up switched-capacitor converter (SCC) under zero voltage switching (ZVS) condition is analyzed in this paper. The ZVS condition (converter operation above its resonant frequency) provides 1) zero-voltage switching, which leads to a relatively higher efficiency compared to zero current switching (ZCS) under the resonant frequency...
This paper presents an isolated DB LLC resonant converter with frequency adaptive phase-shift modulation control which overcomes the unity gain problem of conventional DB converter. The proposed control maintains the Zero Voltage Switching (ZVS) to all switches under all operating voltage and load variations. The control proposed for this circuit based on two control variables: switching frequency...
Traditionally, single-input-multi-output power converters are used to power different parts of a system assembled on a printed circuit board (PCB). The imperfections of this strategy are well-known and include complicated PCB design and thermal management, poor load side voltage regulation, and reduced power density and efficiency. A DC distributed bus, obtained using a resonant LLC bus converter,...
LLC resonant converters are widely employed in industrial applications due to their high efficiency and power density. The design of closed-loop controllers for these converters is particularly challenging due to its non-linear behaviour and many different operating modes. The traditional linear techniques that are usually employed for this application require complex analysis or the use of empirical...
This paper discusses a MHz isolated HV/LV DC-DC converter for automotive applications. The proposed circuit is constructed with a low cost structure by using multitransformer and Si-MOSFETs to achieve frequency multiplying. Three circuit configurations namely, cascaded-type, parallel-type and cascaded-parallel-type, are considered and discussed. Fundamental control and switching behaviors are explained...
Recently, the medium frequency power electronic traction transformer (PETT) has received increased attention in the rail transit applications due to its small size, light weight, more space availability for passengers, multiple interfaces and other additional functionalities. However, the switching frequency is limited by the thermal tolerance of semiconductors which deteriorate as the switching frequency...
Envelope Tracking (ET) Technique can remarkably improve the efficiency of the power amplifier (PA) in the modern Mobile Communication Base Station. Switch-Linear Hybrid (SLH) ET power supply has become the mainstream structure, which gives consideration to high efficiency and high bandwidth. However, the SLH ET power supply with single switching converter suffers a low efficiency as increasing the...
Single stage power factor corrected (SSPFC) AC-DC converters are attractive in particular applications because they are less expensive than conventional two-stage converters. One of the main drawbacks of SSPFC converters, however, is that their intermediate DC bus voltage varies considerably when used in universal voltage range applications. A new method for reducing the DC bus voltage variation for...
In the field of high-speed electrical drives, the use of SiC MOSFET inverters represents a viable solution since this kind of devices allows an improvement of the converter efficiency. Notwithstanding issues related to the high frequency operation of the SiC MOSFET's, like the failure of the motor winding insulation due to the increased electrical stress and hence a reduced system reliability, are...
48V voltage regulator modules (VRMs) are critical for telecom power supplies, and is becoming popular for future data centers. By using a novel sigma converter topology, an outstanding performance in terms of efficiency (94%) and power density (420 W/in3) have been demonstrated in [11]. Both the efficiency and power density are much higher than state-of-art solutions. The sigma converter is a quasi-parallel...
The Class E dc-dc converter, operating with the switching frequency up to multi-megahertz, is usually regulated by the basic ON-OFF control. In this paper, it is found that in the basic ON-OFF control, the resonant inductor current of the Class E dc-dc converter will be increase with the rise of the input voltage, which will enhance the output capacity of the converter and also increase the ON-OFF...
The second-harmonic circulating current in the phase legs of modular multilevel converter (MMC) leads to additional power losses. Existing circulating current suppressing strategies are realized by injecting the second-harmonic component in arm voltage reference. This paper presents a modified circulating current suppressing strategy including two controllers with a fixed-band submodule (SM) state...
The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid State Transformer. The proposed topology uses a high-frequency transformer to optimize the size and weight of the converter. This converter has the capability of operating at fluctuating load conditions while it keeps the voltage regulated in different operation point. The converter is designed to maintain...
In Digital Grid which has been proposed as a new electric power grid, multi-inverters are operated in parallel and it may cause the cross-current among those inverters, since inverters do not have synchronizing mechanism. In this study, the authors propose a method to control the cross-current caused by the difference in switching frequencies of multi-inverters in parallel operation. An indirect hysteresis...
The aim of this paper is the conversion of the classical hysteresis controller into a constant frequency hysteresis current controller. The classical alternative to the hysteresis controller is the proportional-integrative controller which gives constant switching frequency and overall better performances with a cost of comprehensive parameter tuning and sensitivity at driven system change. The hysteresis...
Ultra-high speed machines have become more and more interesting to researchers in the past few decades. Switched reluctance machines (SRMs) are very attractive to researchers due to their simple geometry. However, traditional control methods are not suitable for ultra-high speed applications because of their super-high switching frequency. In this paper, a constant volts per hertz control for ultra-high...
In this paper, a constant frequency hysteresis-Space Vector Pulse Width Modulation (CFH-SVPWM) current tracking control strategy for parallel hybrid active power filter (APF) is proposed. Adaptive hysteresis bandwidth (AHB) is calculated according to the hysteresis current controller, which could ensure that the switching frequency of power devices is constant value with little deviation. And selected...
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