Search

The total harmonic distortion (THD) of a waveform is a standard way to quantify its deviation from a sinusoid. In three-phase systems, we are interested in minimizing 3THD: the component of THD produced by odd nontriplen harmonics. However, its definition involves an infinite sum, making it difficult to evaluate and analyze. This paper solves the problem of finding equivalent closed-form expressions for the 3THD of a staircase waveform. In particular, two expressions are rigorously derived, which reveal 3THD to be a piecewise differentiable function. One expression is shorter but describes the pieces implicitly. The other is longer but describes the pieces explicitly. We minimize 3THD using the closed-form expression and provide a comparison with previous techniques. Finally, we provide experimental results that show close agreement with the theoretical results.

Inductive power transfer (IPT) is commonly used to transmit power from an extended loop (track) to a number of galvanically isolated movable pick-ups. To maximize the power transfer and minimize converter requirements, various compensation circuits have been proposed for both the track (primary) and the pick-up (secondary). This paper investigates the suitability of the LCC series-parallel compensation for IPT primary design. A new compensation-circuit design procedure is proposed that considers high-order current harmonics and results in inverter zero-current switching. The proposed compensation is compared with the classical compensation designed for zero phase angle between the inverter voltage and current fundamental components. Expressions for the bifurcation boundary, voltampere rating of reactive-compensation elements, and the current at the moment of switching are derived and analyzed. Analytical results are verified both via PSpice simulations and experimentally using a 1-hp MOSFET-based prototype.

This paper presents a cascaded H-bridge inverter topology for the application of secondary-use batteries as grid-connected energy storage. The proposed control strategy allows a degree of control over individual battery currents while the total system follows an arbitrary current command. This enables the aggregation and optimal use of battery packs with different capacities and states of health, overcoming a significant drawback of existing implementations.

The 12-pulse diode rectifier has been widely used in high power applications. Although the dominant 5th and 7th harmonics of the input current are canceled out, the total harmonic distortion is still well above 5%. Therefore additional filtering is required to meet the pertinent standards. In this paper, several methods that deal with the input current harmonics are reviewed. The fundamentals behind these methods are discussed. By utilizing the concept of virtual resistor, a new approach is proposed in this paper to, not only eliminate the AC input current harmonics, but also eliminate DC output voltage harmonics. Moreover, the energy storage integration is possible with the proposed method. We analyze the control and operation of the proposed method. Simulation and experiment results verify the analysis.

The concept of track sectioning of roadway power system has been presented long time before. But the implementation of this concept is rarely found in literature. A solution based on the idea of dual-powered track sections is proposed in this paper. Current balancing issue along with this new topology is discussed and solutions are provided. Different control strategies are compared to find the optimal control for this topology.

This paper looks at the optimizing the electric vehicle supply equipment (EVSE) design for level 3 DC charging stations. By studying the power demand of the charging station, we conclude that the size of the grid tie can be reduced substantially by sizing for average rather than the peak power demand. Therefore the charging station architecture with a single AC/DC conversion and a DC distribution to DC/DC charging units is proposed. An energy storage system connected to the DC bus is used to supply power when the demand exceeds the capability of the grid tie. Specifically, this paper looks at the integration of energy storage on the DC bus to (1) provide power to the chargers in instances when their requirements exceed the grid tie capability (2) eliminate DC side ripple and (3) eliminate AC side harmonics.

In this paper we present a new circuit design for multi-pickup high-power inductive power transfer systems. The proposed design combines parallel compensated resonant tank with tri-state boost converter. By synchronizing tri-state boost switching period with the half-period of resonant tank voltage, we position the inherently discontinuous current pulse drawn by tri-state boost to control both active and reactive power flow from the resonant circuit to tri-state boost. Controllable reactive current can be used effectively to emulate appropriate inductance or capacitance to tune the resonant tank and achieve optimal power transfer.

This paper studies three fundamental switching patterns for resonant converters to achieve Zero Voltage Switching (ZVS) operation. To evaluate the performance of the three control methods, three resonant topologies are taken into consideration: series resonant, parallel resonant and seriesparallel resonant. The criteria functions for ZVS operation are derived for each control method and topology. The results show that the Asymmetrical Clamped Mode control (ACM) can guarantee lower switching frequency than other two control methods while keeping ZVS operation. Moreover, the circulating power for each control method is analyzed. The relationships between the switching frequency and the maximum power transfer of the three resonant topologies are derived and the series-parallel resonant topology shows a superior characteristic. Experiment results are given to verify some of the results.

In this paper the optimum design of a fast-charging station for PHEVs and EVs is proposed to minimize the strain on the power grid while supplying the vehicles with the required power. By studying the power demand of the charging station, a conclusion is reached that the size of the grid tie can be reduced substantially by sizing the grid tie for the average rather than the peak power demand. Therefore the charging station architecture with a single AC/DC conversion and a DC distribution to DC/DC charging units is proposed. An energy storage system is connected to the DC bus to supply power when the demand exceeds the average that can be provided from the grid. Various topologies for both the AC/DC and DC/DC conversion are studied to find the optimum design for this application.

There is a growing interest on plug-in hybrid electric vehicles (PHEV's) due to energy security and green house gas emission issues, as well as the low electricity fuel cost. As battery capacity and all-electric range of PHEV's are improved, and potentially some PHEV's or EV's need fast charging, there is increased demand to build high power off-board charging infrastructures. A charge station architecture for municipal parking decks has been proposed, which has a DC microgrid to interface with multiple DC-DC chargers, distributed renewable power generations and energy storage, and provides functionalities of normal and rapid charging, grid support such as reactive and real power injection (including V2G), current harmonic filtering and load balance. Several non-isolated bidirectional DC-DC converters suited for charge station applications have been reviewed and compared, as the major focus of this paper. Half bridge converter is a good candidate but it is difficult to maintain high efficiency in wide battery pack voltage range. A variable frequency pulse width modulation (VFPWM) scheme is proposed to mitigate this issue. Finally three-level bi-directional DC-DC converter is suggested to be employed in this application. A 10kW prototype verifies that 95.1–97.9% full load efficiency can be achieved in charging mode with 180–360V battery pack voltage. In addition, the inductor size is only one third of the half bridge counterpart, which is a great advantage for high power converters.

Economic and environmental issues are main motivation for developing efficient and sustainable electrical vehicle for urban transportation. Electrical vehicles (EV) have two main advantages compared to hybrid and gasoline vehicle: eliminated tailpipe emissions and simplified drive-train. However, electric vehicles have a limited range between recharges when fitted with the current state-of-the-art energy storage. To mitigate the limitations of the energy storage technology, we propose to use inductively coupled power transfer (ICPT) to supply power to the vehicle while it is moving. ICPT is an efficient technique for transferring power with no physical connection between the source and the load. In this paper we investigate the ICPT requirements for two types of vehicles operating in combination with ICPT system. The first vehicle makes use of a battery as primary and ICPT as secondary energy source for electric vehicle supplying. The goal is to achieve 300 miles range of covering. The second uses electrochemical capacitors (Ultracapacitors) as the power source and ICPT as the energy source. The goal is to provide unlimited range for the vehicle. The result is system analysis of feasibility of battery-ICPT and ultracapacitor-ICPT combinations for different driving conditions and vehicles as well as rough evaluation of expected length and optimal positions of ICPT track for specified driving cycles.

The cyclically switching operation of a novel zero-voltage-zero-current-switching three-level converter is briefly presented. Based on a steady-state time-domain analysis of each equivalent switching topology, an average model is obtained. Small-signal open-loop ac line-to-output, control-to-output, and output-current-to-output-voltage transfer functions are deducted. The stability, gain margin, and phase margin of the open-loop transfer functions are studied. After designing the closed loop, the study of the audiosusceptibility and closed-loop output impedance allows for a dynamic analysis: the transient responses to changes in the input voltage and load current are obtained. The results got from the small-signal modeling are compared and confirmed by those obtained by PSPICE simulation and those measured in the laboratory, on an experimental converter of 4.5 kW