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This paper presents an ac ripple repression method for neutral-point voltage of three-level inverter system with electrolytic capacitor less. To reduce the volume of three-level inverter system, electrolytic capacitor with huge capacitance is must eliminated from dc-link. In the inverter system applying film capacitors, however, the ac ripple component in neutral-point voltage of dc-link is increased...
As a key component of DC medium voltage breaker, the switch mechanism is required to open in high-speed and can withstand the breaking voltage which is generated during opening motion. Thus, the design of driving circuit of switch mechanism is very important to optimize the mechanism structure and improve mechanism opening characteristics. First the motion principle of high-speed switch was given...
This paper presents a flyback converter based partial power processing structure for battery energy storage system (BESS). It combines both of the battery balancing functionality and power stage regulation functionality into one system. The proposed BESS only have one control variable which is the common duty cycle for all the flyback converters. It is used for the voltage or current regulation. There...
This paper presents a DC microgrid integrated dynamic voltage restorer (DVR) system to mitigate the grid voltage sag and swell. The DC source of the DVR is the DC microgrid, including the PV array and hybrid energy storage system consisting of lithium-ion battery and supercapacitor. Compared to the conventional DVR supplied by pure energy storages, the DC microgrid will prolong the operation the DVR...
A novel positive to negative voltage converter and a novel LDO regulator are proposed in this paper. Compared with the conventional voltage converter, the proposed one has a higher efficiency for a certain process. The novel negative voltage LDO circuit has a good temperature characteristic with a simple and chip-saving control circuit. The proposed whole circuit is verified with simulation in CSMC...
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...
This paper proposes modeling and control system design for PV based Quasi-Z-Source Inverter (QZSI) for grid connected applications. The control system is designed based on the dynamical characteristics of the converter and introduces two cascaded controllers. Firstly, output current controller designed in the stationary frame. The second is DC-link voltage controller. Also, Modified Direct Incremental...
Recent years, multilevel inverters have become more attractive for researchers due to low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a three-phase cascaded H-bridge quasi-switched-boost inverter (CHB-qSBI). The advantages of the proposed inverter are as follows: buck-boost voltage with single stage power conversion, reduced...
This paper discusses the dead-time effect of dual bridge series resonant DC/DC converter (DBSRC). The phase-shift modulation is usually adopted in DBSRC. However, the phase-shift angle is usually small, and voltage polarity reversal (VPR) may occur in dead-time, which may deteriorate EMI/EMC and increase loss. This paper analyzes the commutation of DBSRC when VPR occurs and proposes a method to eliminate...
In order to reduce the ripple of DC-link voltage and capacitor current, this paper presents a method to select suitable capacitance for the rectifier (full-wave controlled) and inverter. Meanwhile, a braking unit is developed to prevent the overvoltage of DC bus. The impact of the length of cable, connected between the braking unit and the inverter, is researched from a mathematical point of view...
In this paper, a step-up dc-dc converter for mobile device applications is proposed. The converter is operated with 1 MHz high switching frequency. The power stage of converter includes an inductor, an output capacitor, MOS transistors and feedback resistors for control loop. The control stage consists of an error amplifier, comparator, a ramp generator for PWM block, bandgap reference and soft start...
The paper presents the method of digital modelling of process of switching on by vacuum switch in capacitive circuits. Currently, there are few descriptions of vacuum switch models used for capacitive circuits switching on. More often researchers focus on vacuum switch models used for switching of the circuits (also previous works of the Authors) and even more often models used for switching of the...
Single-phase inverters suffer from double-frequency ripple of the input power. For mitigation, an input capacitor is applied but the fluctuation range of power across it is limited according the desired fluctuation in the dc-link voltage. To realize power decoupling without changes in the main circuit and in the control strategy of it, an additional independent power decoupling circuit can be applied,...
This paper presents the design and analysis of a Modular Multilevel Matrix Converter (M3C) working as a frequency changer to facilitate the deployment of offshore Low Frequency AC (LFAC) transmission system. The converter consists of nine branches, each with n cascaded H-bridge submodules connected in series with the arm inductor. The paper proposes a new energy balance control method, which manages...
This paper presents an output-capacitorless low-dropout (LDO) regulator with with −132dB power supply rejection ratio (PSRR) at 1KHz. By using a Rising-Class-A voltage buffer, the non-dominant parasitic poles can be pushed to higher frequencies and leads to good stability in power supply rejection ratio (PSRR) performance. The proposed circuit is designed with 0.18-µm CMOS process technology. The...
With the development of wireless sensors, wireless technology and micro-electromechanical systems, the micro power supply system attracts people more attention. And since mechanical vibration energy is widely distributed in nature and is subject to less restrictive environmental factors, it is gradually becoming a new study object for energy collection. At present, according to the latest study, the...
Traditional mechanical OLTC has some disadvantages while changing the taps, such as causing arc, switching slowly, having high malfunction rate. This paper proposed a kind of intelligent OLTC which equips with vacuum interrupters controlled by permanent magnetic actuators (PMA) as its switching parts. In this paper, the overall structure and electrical circuit scheme of the OLTC were designed on the...
The boost inverter is an attractive solution for photovoltaic (PV) microinverters since it is a single stage architecture. Indeed, in comparison, most of the microinverters topologies consist of two-stage structures, a DC-DC converter for voltage elevation and an inverter for grid connection, resulting in a lower efficiency. The boost inverter consists of two DC-DC boost converters connected in differential...
This paper proposes the control strategy of a multi-input boost converter for renewable energy system applications. The desired high output voltage with a constant level can be achieved using the multi-input boost converter. The low multi-input voltage sources are generated from renewable energy sources such as PV modules and wind turbines. The control of the multi-input boost converter is based on...
❑ Context: DC railway vehicles are subjected to surge transients specific to the traction system environment. ❑ Transient Event Specifications: • Standards. • Transit authorities may specify their own requirements. • Each project requires custom design. ❑ Vehicle Manufacturers Main Task: • Demonstrate during the qualification testing phase the performance of both the equipment and the overall system...
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