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This paper proposes a new developed switched-capacitor converter to achieve high-voltage pulses with adjustable voltage level and frequency. The proposed topology generates repetitive high-voltage pulses by using low-voltage power supply with reduced number of components, including power semiconductors and capacitor. Therefore, a converter based on switched-capacitor units with high voltage gain and high efficiency can be achieved. Operation principles and design steps of the converter as well as comparative study with conventional converters are described in this paper. Finally, simulation and experimental results of a two-stage structure of the proposed circuit validate the operation principles and features of this topology. [ABSTRACT FROM AUTHOR]

Self-powered realization for synchronous switching circuits is a hot spot for piezoelectric vibration energy harvesting. As a well-known approach, the electronic breaker is widely used for its simplicity and reliability. It plays an important role on the performance of the piezoelectric generator by affecting the available open-circuit voltage and the switching phase lag. In this paper, a comprehensive model is developed for improved performance analysis with missed factors included in comparison with previous investigations. The combined influence of the envelope resistor and the capacitor on both the phase lag and the open-circuit voltage is newly considered while the additional phase lag effect induced by charging the switch parasitic capacitance with the envelope capacitance is supplemented. Experiments and simulations validate the proposed model with better accuracy and the results show that these supplemented factors are important to the generator performance, especially for the micropower energy harvesting with small piezoelectric capacitance or displacement magnitude. Moreover, more detailed design guidelines are deduced from the proposed model. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel current link topology with a diode rectifier and magnetic energy recovery switch (MERS) using a current source inverter for offshore-wind-farm application. Despite the use of a diode rectifier, the proposed topology is capable of regulating individual turbine torque partially. Because offshore wind condition is more stable and has less turbulence intensity (typically 0.08) than that of onshore wind, the individual full-range controllability realized typically by pulse-controlled converters is not necessary. Instead of them, the proposed scheme, a diode rectifier with MERS, has only partial controllability of the individual generator torque which is estimated to be sufficient to achieve the maximum power point tracking operation for offshore-wind-farm application. The proposed topology is aiming to be applicable for offshore wind farms where maintenance reduction is conclusively a critical issue because of the inaccessibility. In this paper, experimental results represent the effectiveness of the topology. Moreover, a new control strategy for offshore wind farms with the proposed topology is also proposed. [ABSTRACT FROM PUBLISHER]

In this paper, the concept of an all-dc wind park with series-connected turbines is investigated as an alternative to the classical ac parallel or radial wind park. This paper presents a literature overview of all-dc wind park concepts with series connection. A three-phase conversion system with permanent magnet machine, ac–ac converter, high-frequency transformer, and diode bridge rectifier is suggested in this paper for the series connection of dc turbines. The dc series park with the suggested conversion system is compared in terms of losses, cost, and reliability to the state-of-the-art park configuration which is the ac radial park with HVDC transmission. It is found that the dc series park becomes comparable with the ac radial design for high ratings of the dc turbines. Furthermore, the comparison shows that emphasis must be put on reducing the losses in the conversion system of the dc turbine and, particularly, the ac–ac converter. Therefore, the efficiency of the ac–ac converter is compared for three different topologies: the direct matrix converter, the indirect matrix converter, and the conventional back-to-back converter. The direct matrix converter is found to be the most efficient, suitable for the suggested conversion system. [ABSTRACT FROM PUBLISHER]

This paper presents a new high-voltage pulse generator, which is based on positive and negative buck-boost (BB) converters fed from a relatively low voltage dc supply. The proposed generator is able to generate unipolar or bipolar high-voltage pulses via operating the BB converters with series or parallel connected outputs respectively using a common input dc source. The components of each converter are rated at half of the pulsed voltage magnitude in the unipolar mode. The converters in the proposed pulse generator operate in discontinuous conduction mode. This enhances system efficiency, as the circuit only operates when it is desired to generate a pulsed output voltage, otherwise the circuit is switched to idle mode with zero current. Detailed illustration of the proposed approach is presented along with a full design of the system components for given output pulse specifications. Finally, simulation and experimental results are presented to validate the proposed concept. [ABSTRACT FROM PUBLISHER]

This paper presents a new buck converter with optimum-damping and dynamic-slope compensation techniques. The optimum-damping control is a well-known current control method, and the proposed dynamic-slope generator can achieve frequency compensation to prevent subharmonic oscillation. When the system is disturbed, the proposed dynamic-slope generator can stabilize the circuit in a single cycle. Hence, the dynamic-slope compensation can be used to replace traditional extra slope compensation in the optimum-damping-control circuit. The measured transient time of the load current is 2 μs from 50 to 500 mA, and 3 μs from 500 to 50 mA. The optimum-damping-control techniques can rapidly reach desired output voltage in 2–3 switching cycles. The experimental and simulation results confirm that the proposed approach can achieve the slope compensation and accelerate the transient response. The proposed converter has been fabricated with TSMC 0.18 μm CMOS 1P6M technology. The converter's operating frequency is 1 MHz, the maximum output current is 500 mA, and the peak power efficiency is 89.68% under 300-mA load current. The chip area is only 1.0376 mm × 1.0599 mm (include PADs). [ABSTRACT FROM PUBLISHER]

This paper studies a distributed consensus algorithm for economic dispatch in a smart grid, which aims at minimizing the total generation cost. The proposed algorithm only needs each generator in the network be aware of its local cost parameters and its neighbors’ virtual incremental cost variables. The proposed algorithm is “anytime.” It does not break the supply–demand balance even in the transient process. It overcomes the defect that the trajectories of traditional consensus based algorithms are not feasible solutions before convergence. The proposed algorithm is also “anywhere.” It is applicable for the jointly connected switching undirected topology. It can gradually drive any connected region of a power system to approach its own optimal state. Simulation studies on several cases demonstrate its effectiveness. [ABSTRACT FROM AUTHOR]

In this paper, a class-D audio amplifier which combines the advantages of the phase-shifted carrier pulsewidth modulation (PWM) and the multiple-level carrier PWM is proposed with a dual-level dual-phase carrier (DLDPC) PWM. The proposed closed-loop amplifier includes a second-order integrator and a DLDPC triangular wave generator. Two sets of 180° out-of-phase triangular waves are used as carriers, and each set has its respective offset voltage level with nonoverlapping amplitude. By performing the double Fourier analysis, it can be found that the linearity can be enhanced and the distortion can be reduced with the proposed modulation. Experimental results show that the proposed fully differential DLDPC PWM class-D audio amplifier features a total harmonic distortion lower than 0.01% with an output voltage swing of $\pm$5 V. [ABSTRACT FROM PUBLISHER]

The switched reluctance machine (SRM) has certain advantages such as robustness and the absence of permanent magnets which have encouraged its use in recent years. One of its applications is as a self-excited generator. This behavior is produced when a capacitor is series or parallel connected to each single phase forming a nonlinear pseudoresonant circuit. This application can be used in isolated sites with a wind turbine for energy generation. This paper describes a novel method used for the specific design of a 1-kW self-excited SRM for wind power applications based on torque considerations. The machine volume, dimensions, finite-element analysis, model verification, simulations, and experimental results are all presented. [ABSTRACT FROM AUTHOR]

This paper discusses the operation of a multiphase system, which is aimed at both variable-speed drive and generating (e.g., wind energy) applications, using back-to-back converter structure with dual three-phase machine-side converters. In the studied topology, an asymmetrical six-phase induction machine is controlled using two three-phase two-level voltage source converters connected in series to form a cascaded dc link. The suggested configuration is analyzed, and a method for dc-link midpoint voltage balancing is developed. Voltage balancing is based on the use of additional degrees of freedom that exist in multiphase machines and represents entirely new utilization of these degrees. The validity of the topology and its control is verified by simulation and experimental results on a laboratory-scale prototype, thus proving that it is possible to achieve satisfactory dc-link voltage control under various operating scenarios. [ABSTRACT FROM PUBLISHER]

Vienna rectifier as generator-side converter of wind energy conversion system (WECS) using a permanent-magnet synchronous generator (PMSG) has several advantages compared to conventional back-to-back inverter, such as higher efficiency and improved total harmonic distortion. On the other hand, direct torque control (DTC) of the generator in WECS is of interest, particularly for low-power applications due to several merits, including fast torque response, insensitivity to PMSG model and associated parameters, elimination of rotor position sensor, and reduced computations. In this paper, the effects of Vienna rectifier voltage vectors on instantaneous PMSG torque and stator flux are derived, and DTC of PMSG by the Vienna rectifier is implemented, considering the constraints imposed by the Vienna rectifier. Experimental tests for a 1-kW prototype are presented, which confirm the simulations and theoretical results. [ABSTRACT FROM PUBLISHER]

This paper presents a new control strategy for power factor correctors (PFCs) used to drive high-brightness light-emitting diodes (HB-LEDs). This control strategy is extremely simple and is based on the use of standard peak-current-mode integrated controllers (PCMICs), reducing its cost and complexity in comparison to traditional PFC controllers. In fact, this method is an alternative implementation of the one-cycle control to PFCs belonging to the flyback family of converters, without introducing high complexity for reducing the total harmonic distortion. In this case, the use of a simple exponential compensation ramp instead of a linear one is the proposed solution for drawing a sinusoidal input current. Moreover, the line current is cycle-by-cycle controlled, and therefore, the input-current feedback loop is extremely fast, which allows the use of this type of control with high-frequency lines. The proposed idea is to apply this simple control to a one-stage PFC in order to design a low-cost ac–dc HB-LED driver. However, the application of this control strategy to PFC belonging to the flyback family of converters is not obvious. Design-oriented considerations about its implementation in PCMIC will be provided. Finally, an experimental prototype of this driver was developed. [ABSTRACT FROM PUBLISHER]

With the increasing use of low-voltage portable devices and growing requirements of functionalities embedded into such devices, efficient dc/dc conversion and power management techniques are needed. In this paper, an architecture for boosting extremely low voltages (about 100 mV) to the typical supply voltages of current integrated circuits is presented which is suitable for power harvesting applications too. Starting from a 120-mV supply voltage, the converter reaches an output voltage of 1.2 V, providing an output current of 220 \mu\A and exhibiting a maximum power efficiency of about 30%. Along with the dc/dc converter, a power management circuit is presented, which can regulate the output voltage and improve the overall efficiency. A test chip was fabricated using a United Microelectronics Corporation 180-nm low-threshold CMOS process. [ABSTRACT FROM PUBLISHER]