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In the conventional variable speed drive, the dc-link including the dc-choke and electrolytic capacitor is bulky with limited lifetime. The slim dc-link drive is thus proposed for the lower cost and longer lifetime by using the film capacitor to replace the electrolytic capacitor and dc-choke. However, such drive system suffers from the potential instability issue, due to the negative incremental...
This paper presents the suppression control of the source current harmonics of the bi-directional isolated AC/DC converter. The proposed circuit consists of three-phase AC to high-frequency single-phase AC matrix converter, high-frequency transformer, and single-phase AC to DC converter. The authors have achieved the soft-switching of all commutations of the both converters. The further downsizing...
One of the commonly used approaches to avoid the short circuit of power devices for pulse-width-modulation (PWM) inverters is to add dead-time into the control signals. The drawback of this approach is that severe distortion in phase currents and output voltages may occur. This paper proposes an adaptive-linear-neuron based nonlinearity compensation strategy to cope with the disturbance voltage caused...
Photovoltaic (PV) energy has been widely interested today because it is clean and endless energy without causing pollution. To produce electricity from solar energy, it would be required an inverter to convert the direct current into alternating current. The inverter is the cause of problems that affect the stability of the power system because it is a switching device served to adjust the frequency...
Lighting system is an important part in everyday life. Today, lighting technology has been developing in many aspects. Technology such as Light Emitting Diode (LED) luminaire has been applied to indoor lighting system to replace conventional luminaire. LED lamps have many advantages such as less energy consumption, long life cycle and environmental friendly issue due to without toxic component. However,...
Condition monitoring of marine propulsion motors is important in improving the overall reliability of a marine electrical power system. The focus of this research is to accurately model and diagnose the local demagnetization fault in a Surface mount Permanent Magnet Synchronous Motors (SPMM). The techniques used here for fault detection is based on time-frequency based signal analysis mainly Hilbert...
A square wave transmission based micro-grid, which is compatible with commercial AC sinusoidal grid components, is investigated in this paper for rural areas. The basic interface circuit unit, square wave generator (SWG) is designed to satisfy bidirectional power flow and square wave transfer. The square wave has larger power delivery compared to sine wave. The circulating current of paralleled SWGs...
The present paper deals with the sensorless harmonic speed control of a drive for repetitive mechanical systems and proposes a harmonic control scheme, in which a proportional-integral controller is dedicated to each single harmonic component of the speed error. In addition, the harmonic speed controller provides information that can be used for the estimation of the load torque and for a diagnostic...
In high-frequency (HF) pulsating voltage injection-based sensor-less surface-mounted permanent magnet synchronous motor (SPMSM) control, inverter nonlinearities and motor parameter asymmetries lead to harmonic errors in the estimated position. To eliminate these errors, the second-order generalized integrator (SOGI) is applied. An enhanced position observer with a selective harmonic error eliminator...
This paper presents the development of a position sensorless controlled synchronous reluctance motor (SynRM) drive. First, the basic vector controlled SynRM drive is established, including power circuit, sensing and commutation schemes. Then the high-frequency injection (HFI) based rotor position estimator is developed to yield the rotor position for making the vector control. After comprehending...
This paper proposes a predictive current mode control boost PFC converter adopting a novel active part switching technique to achieve both robust current shaping control to disturbances and high power conversion efficiency. This strategy consists of controlling the switching stop angle near the peak of the input voltage through the output voltage control and controlling the switching stop period near...
Recently, multiphase induction machines are proposed to replace traditional three-phase drives in low-voltage large power applications with high fault-tolerance ability. This paper concentrates on their speed sensorless vector control algorithm of multiphase induction machine. A full-order adaptive observer is adopted to observe the rotor flux and rotor speed, and a harmonic suppression method combined...
This paper proposes the class-E rectifier with harmonic-current injection. For injecting the harmonic current, a harmonic-component resonant circuit is added to the class-E rectifier. By injecting the harmonic current with proper amplitude and phase, the peak value of the diode voltage and current can be reduced effectively. This paper shows the design example along with the experimental results....
Interior permanent magnet synchronous motors often work under flux weakening state in electrical vehicles for higher speed but faults, such as overcurrent and overvoltage, might occur during that process, after which the power transistors are closed immediately and the battery packs are charged through three-phase uncontrolled rectifier composed of six fly-wheel diodes. It is called uncontrolled generation...
This paper proposes a controller design to compensate the current harmonics from the nonlinear load when a grid-connected inverter operates as an active power filter. When the LCL filter is installed at the output of inverter, the controller should be designed differently depending on the location of the nonlinear load. As this nonlinear load is connected to the grid before or after the grid side...
Photovoltaic (PV) power generation has become viable alternative due to the advantages of no fuel cost and abundance of sunlight. In a grid-connected PV inverter system, besides stability and reliability, the efficiency is always an important factor. To generate active power effectively, the grid-side current must be in phase with the grid voltage. Further, the current harmonics must be low enough...
In low-voltage ride-through or unbalance gird voltage condition, the fundamental fluctuation in the neutral-point (NP) voltage of three-level voltage source converter will appear under imbalanced grid voltage situation and has not been researched in detail. A new NP current model under imbalanced grid is developed to investigate the limitations of conventional nearest-vector modulation and to give...
This paper proposes a reducing technique of carrier noise of PWM inverters without increasing the carrier frequency during zero-speed drive of a permanent magnet motor. The feature of the proposed technique is that the frequency component of the carrier noise is diffused by zero-sequence voltage. In particular, the zero-sequence voltage is randomized by the M-sequence signal and added to the voltage...
The nonlinear loads in microgrid not only distort the voltage but also degrade the harmonic power distribution in a conventional droop-controlled microgrid. This paper starts with analyzing the trade-off between voltage total harmonic distortion (VTHD) and harmonic sharing effectiveness. A multi-framed droop controller is proposed to improve the harmonic power sharing without deteriorating VTHD by...
This study proposes an enhanced current control strategy to eliminate DC and harmonic current at the output current of three-phase grid-connected inverters caused by DC offset and scaling error in grid voltage measurement. The proposed current controller designed in the stationary (α-β) reference frame is developed with a proportional integral (PI) plus three resonant controllers where the resonant...
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