This paper proposes an improved position sensorless control method for switched reluctance motor (SRM) based on a sliding mode observer (SMO) using nonlinear polynomial flux linkage model. Firstly, in order to balance...
This paper proposes an improved position sensorless control method for switched reluctance motor (SRM) based on a sliding mode observer (SMO) using nonlinear polynomial flux linkage model. Firstly, in order to balance the accuracy and complexity of SMO, a nonlinear polynomial flux linkage model with variable coefficients is introduced. Then, a modified SMO utilizing the switching function is designed to estimate rotor position and speed. Finally, comparison simulation results are presented to verify the accuracy and robustness of the proposed sensorless method.
The output voltage of the traditional diode-rectified doubly salient electro-magnetic generator (DSEG) system will change significantly when the load current changes rapidly. Besides, it’s difficult to regulate the o...
The output voltage of the traditional diode-rectified doubly salient electro-magnetic generator (DSEG) system will change significantly when the load current changes rapidly. Besides, it’s difficult to regulate the output voltage by adjusting the field current because of the large time constant. In order to solve the problem, a modified angular position control (APC) strategy based on the controllable rectifier DSEG system is proposed. Using the back propagation neural network (BPNN) to predict proper switching angles according to the speed and field current, the improved APC strategy is helpful to slow down the charge and discharge process of the capacitor and greatly reduced the output voltage fluctuation. Finally, the effectiveness of the proposed strategy is proved by simulations on a 6/4 pole DSEG with controlled rectifier.
With the rapid development of global low-carbon energy, water electrolysis for hydrogen production attracts significant attention as a crucial energy conversion method. For industrial electrolysis setups, the large-sc...
With the rapid development of global low-carbon energy, water electrolysis for hydrogen production attracts significant attention as a crucial energy conversion method. For industrial electrolysis setups, the large-scale application is limited by the issue of low efficiency. To address this issue, one promising approach is to regulate the electrolysis process by imposing an external magnetic field. However, current relevant studies usually focus on static electrolysis systems within beaker-like containers, ignoring the narrow flow channel structure and the circulating flow of electrolyte in industrial electrolyzers. Therefore, an electrolyzer using a microfluidic platform as a phantom is established. Based on the platform, this paper investigates the effects of magnetic field under different magnetic flux densities, electrolysis voltages and electrolyte flow rates. The results indicate that the magnetic field contributes to an enhancement in current density and the increase in current density shows a trend of first increasing and then decreasing with the increase of voltage or flow rate within a certain range. Moreover, The improvement increases with the increment in magnetic flux density.
Parameters’ accuracies are essential for model-based sensorless control in synchronous machine drives. In this paper, a multiparameter adaptive observer and a position error optimizer are presented to obtain real-tim...
Parameters’ accuracies are essential for model-based sensorless control in synchronous machine drives. In this paper, a multiparameter adaptive observer and a position error optimizer are presented to obtain real-time parameter information in the absence of rotor position data for unified synchronous machine (SM). The adaptive observer is based on the misaligned dq-axes’ small-signal impedance model where dq-axes EMF coupling terms are well considered. All parameters can achieve high accuracy under entire operation region. In the case of isotropic SMs, the estimated parameters can be directly utilized in the model-based observer to acquire high precision position observation. And, for anisotropic SMs, an optimizer is introduced to correct parameter inaccuracies caused by position error. The effectiveness of the proposed adaptive observer and optimizer is evaluated through a combination of experiments and simulations, providing comprehensive validation of their performance. 1
The dc-link current is an important parameter in voltage source inverter (VSI)-fed Interior Permanent Magnet Synchronous Motor (IPMSM) system. On the one hand, the average value of dc-link current reflects the power l...
The dc-link current is an important parameter in voltage source inverter (VSI)-fed Interior Permanent Magnet Synchronous Motor (IPMSM) system. On the one hand, the average value of dc-link current reflects the power level of dc-side and plays a crucial part in system protection, power management and efficiency optimization. On the other hand, using estimation method instead of dc-link current sensor to obtain the value of dc-link current can reduce system cost and increase system reliability. However, in practical application, some non-ideal factors such as digital delay, dead time effect and current sampling error caused by low carrier ratio may affect the accuracy of estimation. Therefore, an accurate dc-link current estimation method for VSI-fed IPMSM drive system with space-vector pulse width modulation (SVPWM) is proposed in this paper. Both simulation and experimental results of proposed estimation method are presented to verify the feasibility and accuracy of the proposed estimation method.
The 2D axisymmetric model of crater with flowable heat transfer is combined with the mass, momentum, and heat transfer equations. However, it is considered that the initial cold cathode surface does not have current d...
The 2D axisymmetric model of crater with flowable heat transfer is combined with the mass, momentum, and heat transfer equations. However, it is considered that the initial cold cathode surface does not have current density. Under the new simulation condition of electric field, two typical distributions of temperature are obtained for different external parameters. At higher pressure relative to the heating efficiency, a distribution of temperature on droplet head much higher than the central area is formed. When the heating efficiency is large enough, the temperature of central area increases continuously, resulting in the same temperature as the metal droplet head.
Controllable reactors (CR) are general FACTS (Flexible AC Transmission System) apparatuses, which have played a crucial role in improving the power flow distribution of the system, adjusting the reactive power balance...
Controllable reactors (CR) are general FACTS (Flexible AC Transmission System) apparatuses, which have played a crucial role in improving the power flow distribution of the system, adjusting the reactive power balance of the power grid, stabilizing the voltage, and improving the stability of the system. This paper summarizes the characteristics of various types of controllable reactors, classifies reactors with different structures, and compares different controllable reactors from the perspectives of reactance change, response speed, harmonic problem, and control accuracy. A transformer-type controllable reactor based on flux compensation is proposed, the design scheme of secondary side multi-winding is adopted to realize the large-capacity reactor, the unity of single control winding and multi-control winding in the application is expanded, and the general principle of controllable reactor is obtained through the control of the “linear two-port network” port, and the design principle of such reactor is summarized.
As a key link between the DC source and the grid, the L-type grid-connected inverter must have good and stable control performance. In this paper, the current inner loop of L-type inverter is studied and the PR contro...
As a key link between the DC source and the grid, the L-type grid-connected inverter must have good and stable control performance. In this paper, the current inner loop of L-type inverter is studied and the PR controller is designed by analog method and direct digital method. The performance differences between the discretization methods are compared, and the effect of sampling frequency on the discrete error is also analyzed. In the direct numerical method, the law between the controller parameters and the open-loop root trajectory is analyzed, and two sets of PR controllers are designed based on this. Through simulation experiments, it is verified that the PR controller designed by the direct digital method in this paper can achieve smaller overshoot and faster regulation.
The safe operating area is an operating area with high reliability for SiC MOSFET, and its degradation may cause power electronic system failure. The safe-operating-area degradation and the failure modes of 1200 V/66A...
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High-temperature superconducting (HTS) cable may suffer from various types of fault hazards during operation, and lead to the quench, endangering cable safety. The temperature distribution along HTS cable is usually i...
High-temperature superconducting (HTS) cable may suffer from various types of fault hazards during operation, and lead to the quench, endangering cable safety. The temperature distribution along HTS cable is usually inhomogeneous, which is a direct factor in determining the superconducting performance and operational stability of the cable. However, it is still difficult to achieve effective monitoring of temperature distribution along the cable in actual projects. In this paper, thermal characteristic of concentric HTS cable under various fault scenarios is analyzed, focusing on the temperature distribution of the cable. The results will provide a reference for the study of condition monitoring schemes for the HTS cable.
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