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A novel, genetic-algorithm based, design method of the passive filter-based phase shifting transformers is presented. The method improves the reliability, effectiveness, and accuracy of the filter. The filter is employed in an interphase power controller (IPC), a FACTS device unique in its power-transmitting properties. The paper demonstrates how the implementation of the proposed filter in the IPC...
This paper proposes a novel seamless transfer control strategy of three-phase grid-connected inverter between grid-connected (GC) and stand-alone (SA) modes which can cover from no load to full load, even in non linear (NL) loads. The three-phase grid-connected inverter which uses in distributed generation (DG) system can be operated in both GC and SA control modes, especially for energy storage systems...
A flux-switching permanent magnet (FSPM) machine using ferrite magnet is proposed to replace the permanent magnet synchronous motors (PMSMs) in elevator doors. In order to improve both mechanical robustness and manufacturability, bridges around permanent magnet (PM) slots have been adopted in the C-shaped core of an FSPM machine. The optimization of the C-shaped stator is conducted, and its prototype...
This paper presents a new power control strategy of grid-connected converter under grid fault conditions. Positive-and negative-sequence reactive power are controlled separately in order to effectively support unbalanced grid voltage. Both maximum phase current limit and maximum active power oscillation limit are taken into consideration which makes the converter operate safely under grid faults....
Severe distortion will occur in the output current of inverter when grid voltage is unbalanced with harmonics contained. In this paper a scheme of repetitive control for three-phase grid-connected inverters with LCL filter under stationary frame is proposed. The THD of the injected grid current is decreased obviously with the proposed scheme. Two separate decoupled control systems can be achieved...
A hybrid method based on artificial neural networks (ANNs) and Quasi-Newton algorithm is proposed to generate the switching angles for selective harmonic elimination (SHE), which makes a compromise among the memory consumption, executing efficiency and the solution precision. Unlike the other ANNs based methods which use ANNs to directly give the final switching angles, this hybrid method just uses...
The AHU (air handler unit) is one of the main research objects in HVAC (heating, ventilating and air conditioning) system containing coils, blower wheel, heater, etc. Most of the high efficiency blower wheels are driven by BLDC (brushless DC) motor. This paper mainly focuses on two severe problems in blower wheel, namely airflow blockage and unbalanced load of fan motor. Early diagnosis of these problems...
The complete design of the current control loop for single-phase inverters connected to weak grids is presented. The problems associated to the design of current control loop when highly distorted grid voltages are present and LCL filters are used to couple the inverters to the grid, are analyzed. Fourier coefficients decomposition is used to obtain an ahead-of-time version for the nonideal voltage...
For LCL-filtered grid-connected inverters, classical control methods such as the proportional grid voltage feedforward, the harmonic quasi resonant (HQR) control etc., are widely utilized to achieve low current distortion. However, the system stability is easily challenged by the grid impedance and the increased number of the paralleled inverters. Therefore, this paper orients to guarantee the harmonic...
This paper introduces a methodology to model and control a single-phase tri state integrated Buck-Boost inverter suitable for low power distributed generation with the capability to operate in grid connected and island modes. The tri-state modulation is adopted in order to achieve power decoupling by means of average inductor current. This way it is possible to control the DC/AC conversion independently...
This paper presents a novel algorithm for in situ efficiency estimation for induction motors operating with distorted unbalanced voltages. The proposed technique utilizes the genetic algorithm, IEEE Form F2-Method F1 calculations, large motor test database and a new stray-load loss formula. The technique is evaluated by testing 3 small- and medium-sized induction motors with 11 different combinations...
The harmonic issue of generator-rectifier system is discussed in this paper. A general method for determining the theoretical harmonic components of the regular sampled symmetrical SVPWM is presented. The analytical expression for SVPWM was validated by comparing the analytical calculated results with experimental measurements. The relationships among Total Harmonic Distortion, modulation index, Carrier/fundamental...
Models of converters based on averaging have been used widely with numerous benefits. Multifrequency averaging (MFA) model can predict both the fundamental and switching behavior of converters and has the faster simulation run times associated with average-value models. Third harmonic injection is commonly used in the modulation signal for three-phase inverters to increase the inverter maximum output...
This paper compares three possible linear motor topologies for an electromagnetic launch system to assist civil aircraft take-off. Assisted launch of civil aircraft has the potential of reducing the required runway length, reducing noise and emissions near airports and improving overall aircraft efficiency through reducing engine thrust requirements. A comparison is made of practical designs of a...
A new bidirectional multilevel converter topology called Hybrid Multilevel Converter (HMC) suitable for high power AC/AC applications is presented. It is based on cascaded connection of multiple half-bridge submodules in addition to nine thyristor-based low-frequency and soft-switched unfolders in a three-phase version. Compared with a conventional modular multilevel converter (MMC), HMC requires...
This paper proposes a novel control method for harmonic power sharing in an islanded microgrid, without employing any control interconnections between the distributed generation (DG) units. The fundamental real and reactive power is shared by implementing conventional P-f and Q-V droop control. A virtual negative output impedance at harmonic frequency is introduced to control the distribution of harmonic...
In the inverter-interfaced AC microgrid (IIAM), when a short-circuit fault occurs at the distribution line, the output fault current of inverter is commonly limited to two times over its rated current due to the limited overcurrent capacity of power electronic device. Therefore, the conventional overcurrent protection principle cannot be applied to IIAM. Aiming at addressing this issue, a new protection...
Induction motor rotor designs are investigated in this paper to reduce secondary winding harmonic losses in hybrid electric vehicle (HEV) applications. The induction motor is more and more popular to use for the traction drive, but its' secondary winding harmonic losses are significantly higher than the usual when having high frequency and high power density in the HEV application. Thus, the major...
The distributed inverters are integrated into grid without coordinated PWM and the switching ripples of inverters are randomly accumulated at point of common coupling (PCC). Global synchronous pulse width modulation (GSPWM) can attenuate the accumulated switching ripples. This paper proposes time compensation method which compensates the time delay of synchronization signals for inverters in distance...
As a mid-range wireless power transfer (WPT) technology, magnetically coupled resonant (MCR) WPT has become a reseach focus in recent years. In this paper, an equivalent circuit model of 4-coil MCR WPT system was presented, along with the formulas of the output power and transmission efficiency. Besides, to comfirm whether spatial misalignments will influence the transmission characteristics of the...
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