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Non-destructive testing (NDT) has preoccupied a growing number of scientists in recent years. In the field of NDT, the eddy current testing is widely used in industry occasions. It is important to optimize the parameters of the planar eddy current coil to improve the sensitivity of non-destructive testing. In this paper, a planar eddy current excitation coil with the multi-frequency signal on a printed...
This paper investigates the harmonic voltage control strategy of direct torque control for five-phase induction generator (IG) system. In high/medium power applications, the generating function requires the performance of fast dynamic response, good static performance and high utilization of the dc bus voltage. For IG generating system, the direct torque control strategy has the advantages of easy...
High-speed and high-capacity flywheel energy storage system with high-performance is a research focus in the energy field. A 200kW, 15000rpm high-speed permanent-magnet machine that used in flywheel energy storage system is investigated in this paper, and its discharge performance is analyzed through establishing a field-circuit coupling model. The relationship between the load and the performance...
This paper presents a symmetrical hybrid nine-level inverter with reduced voltage sensors. A capacitor voltage estimation method is proposed based on phase-shifted PWM by only measuring the total DC-link voltage and the multilevel phase voltage. Under certain conditions, a modified algorithm to further reduce the number of voltage sensors is given. Simulation results are presented to demonstrate these...
Owing to Insulated Tubular Bus-bar has a significant advantage in the way of mechanical strength, current-carrying capacity, insulating performance and so on. Currently, it widely applies to electric power, petrochemical engineering etc. However, the device operation stability is low, frequent failures and bad influence, due to lacking of correlative standard and management. Most of these failures...
This paper presents a multifunctional interface circuit for the battery-ultracapacitor hybrid energy storage system (HESS). Both the voltage equalization of the battery banks and energy exchanging between two kinds of energy source will be realized, by using the appropriate control strategy. Thus the reliable work and the health of the battery bank can be maintained, and the ultracapacitor (UC) can...
This, paper proposes a method to eliminate the dc component in the measured three-phase grid voltage as the input signals of phase-locked loop (PLL). The dc component in the input signals of PLL causes a low-frequency oscillation of grid frequency. The dc component elimination can be achieved by replacing the integrator in the second-order generalized integrator (SOGI) with a differentiator, named...
A control scheme of the voltage ripple suppression for the permanent magnet exciter generator is proposed in this paper. The output voltage of the permanent magnet excitation generator is affected by the field current, load current and the engine speed. The engine speed can be controlled by the engine governor. However, the actual frequency changes at starting and sudden load variation. As a result,...
This paper proposes a novel technique to estimate online the inductances of a Permanent Magnet Synchronous Machine (PMSM) based on the measurement of the current derivatives excited by two active-voltage vectors and one zero-voltage vector within a PWM cycle. The d- and q-axes inductances of PMSMs are calculated during normal operation of the drive system. The influence of the magnetic saturation...
This paper presents a sensorless control method for IPMSMS drives over a wide speed range operation, including zero speed. The rotor position estimation of this method is based on relating the measured current derivative response which excited from fundamental PWM sequences to the incremental inductance. Compared to other saliency tracking sensorless control schemes, this method doesn't require additional...
The hybrid AC/DC microgrid structure is considered to be the future trend of power systems, due to the vital necessity of connecting more renewable energy sources and storage elements to supply modern AC and DC loads. This paper proposes a power sharing and control strategy for hybrid AC/DC microgrids using the droop control technique. A new structure of the hybrid microgrid is suggested by connecting...
In this paper, more than ten different iron loss models are experimentally evaluated, which covers alternating and rotating fields, influence of temperature, DC bias flux density and distorted flux density due to PWM inverter. Iron loss models considering alternating fields are evaluated by the measured results of a lamination ring specimen. The iron loss model considering rotating field and nonsinusoidal...
A sliding-mode model reference adaptive (MRA) observer-based model predictive current control (MPCC) strategy is developed for permanent magnet synchronous motor (PMSM) drive systems with DC-link voltage sensorless. Generally a DC-link voltage sensor is indispensable for PMSM drive fed by voltage source inverter (VSI) to implement MPCC. In response to DC-link voltage sensor fault, by combination of...
This paper examines several techniques for determining the parameters of the Brushless Doubly Fed Reluctance Machine (BDFRM). Even though the mathematical model for this machine is like that of a double-fed induction machine, the very high leakage inductances prevent the use of the normal locked rotor/unloaded rotor tests. The accuracy of the parameters found is validated by machine testing and comparison...
Insulation failure between the electrical sheets of electrical machines or transformers might occur due to the burrs formed during the cutting process. Together with welding seams or screws used to hold the stack together, the burrs provide a conducting path for eddy currents. In this paper, equivalent conductivities of the EI core with and without interlaminar contacts are determined using 3D finite...
In this paper, position sensorless control method of IPMSM applying three shunt sensing PWM inverter using predictive current for phase current reconstruction and EMF calculation is proposed. Considering the price and volume of the system, a motor drive system applied with shunt and sensorless has been recently studied. However, there is some area that cannot measure three phase current especially...
A hybrid railway power conditioner (HRPC) is developed based on chopper cell modular multilevel converter (MMC) with four legs. The HRPC is able to compensate unbalance currents and reactive power. Its operational voltage at one phase is much lower than the voltage of the railway supply system. This phase of the MMC is connected to the 27.5kV bus without coupling transformer by using a MMC. The application...
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