Iet Electric Power Applications最新文献

An overall investigation of the electromagnetic force, vibration, and average torque of the Interior Permanent Magnet Synchronous Motors (IPMSM) in the dq model for electric propulsion ships is carried out, and the electromagnetic vibration characteristics of the PMSM under the vector control strategy is explored. Firstly, the space and frequency characteristics of the electromagnetic force of the dq model motor are derived using the Maxwell stress tensor method, and the influence of the dq-axes magnetic field on the electromagnetic force under different loads is discussed in detail. Secondly, the finite element method is used to verify the influence of dq-axes currents on motor electromagnetic force, vibration, and average torque. Finally, the experiments are conducted on an 8-pole 48-slot IPMSM, and the results are consistent with the theoretical analysis and simulation results. The results indicate that the electromagnetic vibration of the PMSM for electric propulsion ships increases with the increase of the current i_q and decreases with the increase of the current i_d. The electromagnetic vibration of the motor can be reduced by selecting the appropriate dq-axes current under the output torque constraint.

The authors propose a time-optimal finite control-set model predictive control (FCS-MPC) formulation, generalised to the three most common non-isolated DC–DC converters (buck, boost, buck–boost) tracking a constant switching frequency. The generalised switching model is used to formulate natural trajectories and the internal dynamic model for all three converters. The proposed FCS-MPC also allows the control designer to implement current and voltage constraints to limit current spikes and voltage deviations, respectively. The proposed FCS-MPC is compared to classical FCS-MPC and boundary controllers that also use natural trajectories for time optimality but at the cost of large voltage deviations. Classical FCS-MPC, time-optimal boundary control and the proposed FCS-MPC have been implemented in PLECS for all three converters. The current constraint does not impact control performance while the voltage constraint improves voltage deviation performances without significantly impacting the control speed compared to time-optimal boundary control. Finally, a hardware implementation of the proposed FCS-MPC on a buck converter proves that the control scheme is time optimal and mitigates current spikes while operating at a constant switching frequency at steady-state.

It is difficult to achieve low heat leakage and leak-free rotary sealing for conventional small- and medium-sized cryogenic liquid pumps (CLPs). This is because the motor in a room-temperature environment is connected to the pump impeller (in a cryogenic environment) via a long transmission shaft. An axial flux-concentration superconducting magnetic coupler (AFCSMC) is proposed for CLP to eliminate the transmission shaft. Firstly, the structure and the operation mechanism of AFCSMC are described. Then, a 2D electromagnetic modelling method for AFCSMC is established based on the H-φ formulation and also validated experimentally in terms of the prediction on the levitation force and the guidance force. Thus, the 2D numerical simulations of AFCSMC are performed in an equivalent static system instead of the actual double rotor motion system in which the moving mesh is quite complicated. It is investigated that dependences of the transmission torque on the key electromagnetic structural parameters, such as permanent magnet arrangement, number of pole-pairs, ferromagnetic yoke, operating slip, and so on. The results indicate that the average transmitting torque is less affected by the operating slip, and AFCSMC can start asynchronously and operate in steady state with a synchronous speed. With the advantages of low loss, risk-free of desynchronising, and overload protection, the proposed AFCSMC can provide a competitive candidate for mechanical power transmission technologies in cryogenic engineering.

A variable flux leakage starter-generator structure designed for helicopters is proposed. The research focuses on investigating the current distribution mechanism of the d-q axis to determine the feasibility of incorporating variable flux leakage (FL) in the machine model. By investigating the magnetic circuit models of machines under various operating conditions, we aim to uncover the performance advantages of variable FL starter-generator for helicopters in different scenarios. Subsequently, a variable flux leakage starter-generator is designed, and a prototype is implemented successfully. The experimental results validate the accuracy of the theoretical analysis conducted.

Accurate calculation of equivalent circuit parameters is a prerequisite for accurately calculating the large-capacity synchronous condenser parameter model. Due to its special transient operating conditions, the high transient magnetic saturation effect during operation causes the non-linearity and time-varying of the equivalent circuit parameters. The field mutual leakage reactance is the critical factor affecting the field current, and the time-varying of the equivalent circuit parameters is closely related to the field current. However, the existing equivalent circuit parameter calculation methods considering field leakage reactance cannot achieve time-varying parameters. A calculation method of time-varying equivalent circuit parameters based on a back propagation neural network algorithm is proposed, which solves the calculation problem of time-varying equivalent circuit parameters considering field mutual leakage reactance. Then, a 300MVar condenser is taken as the research object, and the proposed method is used to simulate the different operating conditions of the condenser and verified by the finite element method and experiment. The results show that the method improves the calculation accuracy of the equivalent circuit parameter model, reduces the calculation time, and applies to different operating conditions.

An online non-model-based procedure is presented for estimating the synchronous generator (SG) dynamic parameters using practical phasor measurement unit (PMU) signals in the presence of uncertainty and noisy data. For this purpose, considering 8th-order approximation, the SGs model is estimated in which, based on evaluating voltage and current phasors achieved from PMU data, dynamic parameters are estimated online. The proposed approach is a generalised concept of the Heffron–Philips model in which the variables and the gain factors are adaptable according to operating conditions. The proposed scheme is an online and non-model-based method in which the SG magnetic saturation behaviours are modelled through multivariable non-linear definition to extend the accurate controlling structure. In this case, two different studies are carried out. In the first study, considering a single SG is connected to the infinite bus, the ability of the proposed method through simulation studies is evaluated. In the second study, the proposed scheme is developed practically in the laboratory whereby performing the experimental structure on different types through real-time working mode, validation of the proposed estimated model through different operating points is evaluated. Experimental results show the effectiveness of the proposed practical scheme for estimating the generator's detailed model and non-linear dynamic parameters through real-time evaluations.

A new adaptive-linear-neuron- (ADALINE-) based dead-time compensation method is presented for permanent magnet synchronous motor (PMSM) drives. It is proposed to suppress the sixth current harmonics adaptively in the synchronous reference frame due to dead-time effects. In order to extract the sixth current harmonics, two ADALINE-based extractors are used without taking into account the electrical lead angle. An improved ADALINE algorithm is used to calculate compensation voltages, taking into account the phase shift of impedance. The proposed method is capable of operating not only at low speed but also at medium and rated speeds in contrast to the traditional compensation method of ADALINE only at low speed. The new method is effective in steady, load dynamic and speed dynamic states with no needs for any extra hardware to detect phase current polarity. The effectiveness of the proposed compensation method is verified on a 780 W PMSM drive through experiments.

A systematic definition of an aircraft generator's “available power” (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady-state performance. Using a geometric, data-driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real-time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real-time implementation.

To address the problem of considerable current distortions in traditional single-vector model predictive control (MPC) method for four-switch three-phase inverter (FSTPI)-fed permanent magnet synchronous motor, a double-vector MPC scheme has been studied. However, it still lacks a sufficient theoretical foundation, causing doubts about its effectiveness. To perfect this deficiency, a novel visualisation analysis scheme considering DC voltage pulsation is presented to demonstrate the validity of the traditional double-vector MPC method for FSTPI. The analysis results reveal for the first time that the traditional double-vector MPC method is not always superior to the single-vector method as there is no zero voltage vector for FSTPI. So, a new virtual voltage vector is defined to compensate the deteriorated control performance caused by the absence of zero voltage vectors, based on which an improved double-vector MPC method is further put forward to reduce the current ripples. Then, the presented visualisation analysis is adopted to demonstrate the validity of the improved MPC strategy under pulsating DC voltage conditions. Finally, a new voltage sector division technology is further put forward to simplify the implementation steps of the presented method. Contrastive experimental studies demonstrate the availability of the improved MPC strategy.

In the cost function of model predictive torque control (MPTC) of permanent magnet synchronous motor (PMSM), torque and flux linkage have different dimensions, and the weighting factor needs to be properly adjusted to optimise the control performance. Therefore, based on the discrete mathematical model of PMSM, the torque predictive error and flux predictive error expressions are mapped to the two-phase static coordinate system, which is equivalent to the distance expressions from the endpoint of the voltage vector to the straight line and to the circle respectively. Because they have the same dimension, they can be directly superimposed to form the cost function proposed, which eliminates the selection process of the weighting factor. Then, the candidate voltage vector is substituted into the cost function in turn, and the optimal voltage vector with the minimum cost function is selected as the voltage input of the next control cycle. Finally, the simulation model and an experimental platform are established to compare the steady-state and dynamic performance of the geometric solution-based weighting factor determined method proposed with other MPTC methods.