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Direct power control (DPC) is an attractive control method for three-phase pulse-width modulation (PWM) rectifiers, due to the merits of simple structure, quick dynamic response and little tuning work. However, conventional switching table based DPC presents relatively high power ripples and current harmonics, which is especially serious when the grid voltages are unbalanced. Introducing space vector...
Full Feed-forward (FF) approach has been proved to be an effective method to suppress the output current distortion of the LCL type grid-connected inverter (GCI) due to grid voltage harmonics. Since most of the existing FF approachs are realized by digital control, a futher study of the digital control based (DCB) FF approach has been carried out in this paper firstly. It is shown that, there are...
Harmonic power can be shared by controlling the equivalent harmonic impedance of distributed generation (DG) units in islanded microgrids. This paper firstly reviews several methods for controlling the equivalent harmonic impedance of DGs and adopts the method based on resistive active power filter (R-APF). Then, a droop relationship between the equivalent harmonic impedance of DGs and their remaining...
This research analyzes the vibration phenomenon in certain types of fractional slot permanent magnet synchronous machines that excites low order radial forces. The study utilizes a motor topology from the group having 12-stator slots and 10-rotor poles (12s10p) to identify and propose several design-based solutions to reduce vibration. Some electromagnetic design feature variations in the motor geometry...
In an Organic Rankine Cycle (ORC) systems, the Permanent Magnet (PM) generator is directly coupled to high-speed turbine shaft, in order to increase system efficiency avoiding introduction of gear-box. On the other hand, current time harmonics induce high frequency currents in rotor parts, which cause a temperature increase. PMs are strongly affected by the operating temperature, since both remanence...
This paper presents an evaluation of noise and vibration in a distributed winding permanent magnet synchronous motor driven by voltage source pulse width modulation (PWM) inverters. The permanent magnet synchronous motor (PMSM) is widely used as an important driving source in a variety of fields. However, it generates electromagnetic noise and vibration because of PWM inverters. This paper describes...
For the control of electric motors, conventional inverters have utilized position and current sensors, but they undesirable in terms of cost and maintenance effort. For this reason, approaches without the sensors are developed by applying back electromotive force or signal injection-based method which also has some problems related to the the deterioration of control performance in low speed range...
Nonintrusive efficiency evaluation method based on the air gap torque and rotor slot frequency is generally used in industry application. However, this method has the following problems: 1) the number of rotor slots should be given in advance; 2) with some special number of pole pairs and rotor slots, the stator and rotor slot harmonics may be aliasing, which may lead to great errors in identification...
This paper proposes a hypothetic silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) power module for the medium voltage (MV) variable frequency drive (VFD). A peer-to-peer comparison between commercial silicon (Si) insulated-gate bipolar transistor (IGBT) and the proposed SiC MOSFET module results in some promising results to support the introduction of SiC power modules...
Multiphase induction machines (MIMs) are attractive for safety-critical applications, because they are able to operate under open-phase fault. On the other hand, algorithms for sensorless speed estimation improve reliability and decrease cost and maintenance. The approach based on rotor slot harmonics (RSHs) is especially popular, due to advantages such as its independence from time-varying parameters...
This paper presents the design of a digital controller for a 600 W Boundary-Conduction-Mode (BCM) interleaved boost converter used in an ac-dc Power-Factor-Correction (PFC) power supply. The output voltage of a typical boost PFC rectifier contains a 2nd harmonic ripple. Therefore to achieve good power factor, the output voltage compensator must have a low bandwidth, in order to sufficiently attenuate...
Current-controlled LCL-filtered inverters are usually paralleled together for interconnecting the renewable energy resources into the grid. When the inverter output impedance is not well designed, the harmonic circulating currents out of the control bandwidth may be easily aroused. To reveal this resonant phenomenon and to enhance the stability of the parallel system, this paper builds the parallel...
Diversifying the role of grid side converters (GSC) associated with distributed generation (DG) may have a technical and economic impact. The increasing number of residential photovoltaic rooftop systems can be exploited by distribution network (DN) operators in order to support and improve the power quality of the grid without considerable further investment. GSC can support the grid during abnormal...
As the penetration of renewable energy sources (RES) increases, variation of system impedance seen from grid-connected converters becomes much larger than expected. In this situation, stable operation of converter becomes more challenging. One of the issues caused by system impedance is resonance harmonic problem. Typically active damping control is used and designed based on the known conditions...
The control of PWM rectifiers under unbalanced network has become an important issue in recent years, especially in the applications with weak grid. Conventional methods is based on voltage oriented control (VOC), which requires several PI controllers in dual reference frame and the sequence extraction of grid/rectifier voltages and currents. To reduce the control complexity, recently direct power...
Power quality of ac bus voltage is a key issue for microgrids. A model-predictive-control (MPC)-based distributed bus voltage compensation methods using inverter-interfaced distributed generators (DGs) connected to the concerned bus is proposed. The presented method can compensate bus voltage unbalance and harmonics and share the compensated current between inverters autonomously, with neither communication...
Permanent magnet synchronous machines (PMSMs) have been used in many applications due to their outstanding advantages such as high torque/power density, high efficiency, light weight and good reliability. However the emerging field of electrical traction gave arise to issues which were in general hardly considered in the past Yet, even though well established methods for eDrive control are available,...
This paper further develops the concept of very large size flash-memory-based pulse-width-modulation (PWM) with the implementation of an over-modulation algorithm for a three-phase inverter. The compensation of voltage for linearization is incorporated within the same flash memory with a multi-optimal PWM generator. Using flash memory demonstrates a low cost alternative to advanced processors. This...
This paper proposes a novel frequency-based predictive sequence extractor that allows to isolate the harmonic components of both voltages and currents needed for the control of grid-tied converters. The proposed method is based on a modification of the Sliding Goertzel Transformation (SGT) that allows to include a predictive behavior with a prediction horizon equal to the processing window needed...
Wound rotor synchronous machines have gained popularity as an alternative to permanent magnet synchronous machines and methods to improve the efficiency of these machines are continuously sought after. At the same time, non-overlap windings have gathered ground because of its associated lower cost and good torque density. However, non-overlap windings are also characterized by relatively high sub...
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