Jinming Yang

High-precision position control of a novel planar switched reluctance motor

This paper presents the position control of a novel two-dimensional (2-D) switched reluctance (SR) planar motor. The planar motor consists of a six-coil moving platform and a flat stator base made from laminated mild steel blocks. Unlike conventional x-y tables, which stack two moving slides on top of each other, the proposed 2-D planar motor has the advantages of simple mechanical construction, high reliability, and the ability to withstand harsh operating conditions. Together with the two linear encoders attached to the x-axis and y-axis, the motor can be controlled under closed-loop mode. To combat the problem of force nonlinearity, this paper proposes a cascade controller with force linearization technique to implement the drive controller. Due to the unique structure of the planar motors magnetic circuit, there is very little coupling between the x-axis and y-axis, and no decoupling compensation is needed. Preliminary results show that the proposed SR planar motor has a positional accuracy of 5 /spl mu/m and a maximum acceleration/deceleration rate of 2 G.

A Self-Tuning Regulator for the High-Precision Position Control of a Linear Switched Reluctance Motor

In the high-technology mass manufacturing industry, high-speed and high-precision motion is an indispensable element in the automated production machines. In recent years, there has been a growing tendency to employ direct drive permanent magnet linear synchronous motors in demanding motion applications. Although the overall performance is good, its implementation cost remains high. This is mostly due to the cost of the Neodymium-Boron magnets, the manufacturing of the magnetic rails, and the precision of the overall mechanics. In this paper, a much cheaper alternative is proposed-to use a low-cost linear switched reluctance motor (LSRM) and an adaptive control strategy to overcome the tolerances and difficult control characteristics inherent in the motor. The LSRM has simple and robust structure, and it does not contain any magnets. However, its force is solely drawn from the reluctance change between the coil and the steel plates. Variations on the behavior of these two elements due to different operating conditions will change the motion behavior of the motor. Also, to keep the overall cost low, the LSRM sets a marginal mechanical tolerance during its mass production. This leads to characteristic variations in the final product. Finally, since the LSRM is a direct drive motor, any variations on the motor characteristics will directly reflect on the control system and the motion output. In this paper, a self-tuning regulator (STR) is proposed to combat the difficulties and uncertain control behaviors of the LSRM. This paper first introduces the motor winding excitation scheme, the model of the LSRM, and the current control method. The LSRM system is modeled as a single-input single-output discrete model with its parameters estimated by the recursive least square (RLS) algorithm. Then, an STR based on the pole placement algorithm is applied to the LSRM for high- performance position tracking. Both the simulation investigation and the experimental verification were conducted. In both cases, the results verified that the proposed RLS algorithm can estimate the parameters with fast convergence. The STR can provide quick response and high precision which is robust to the change of system parameters. Combined with STR control, the LSRM is a low-cost solution to fast, accurate, and reliable position tracking for many demanding motion control applications.

High-Precision Position Control of a Linear-Switched Reluctance Motor Using a Self-Tuning Regulator

High-precision position control of linear-switched reluctance motor (LSRM) is important in motion-control industry. The static model-based controller sometimes cannot give satisfactory output performance due to the inherent nonlinearities of LSRM and the uncertainties of the system. In this paper, a self-tuning regulator (STR) based on the pole-placement algorithm is proposed for high-precision position tracking of the LSRM. Following the time-scale characteristics analysis of LSRM position-tracking system and force-characteristic investigation, the position-tracking model is treated as a second-order system. Different from the static model-based control schemes, the dynamic model of the LSRM can be obtained by online estimation. Also, some practical aspects are taken into account. Owing to the unmodeled dynamics and high-frequency measurement noises, there are some oscillations in the practical control signals, and they can be reduced by a properly designed filter. Both the simulation and experimental results demonstrate that, in the control of the proposed STR, the position-tracking system can reproduce the reference signal with the desired performance in harsh ambient. These results confirm that the method is effective and robust in the high-precision position tracking of LSRM.

Position Estimation and Error Analysis in Linear Switched Reluctance Motors

In this paper, a continuous position estimation scheme is presented for linear switched reluctance motors (LSRMs). The scheme uses diagnostic current injection into an unenergized phase to detect the motor position. This paper proposed that a new current integration index be used to quantify the measurement of current waveform. Hardware implementation results demonstrate the effectiveness of the proposed estimation scheme for the LSRM. This paper also performs a study on the accuracy of the estimated position. Through the detailed experimental data, the approach of polynomial fitting is compared with the lookup table with regard to characteristic curve representation. The estimation error distributions and their standard deviation show that the accuracy and precision are close between these two approaches.

Sliding Mode Control of Active and Reactive Power for Brushless Doubly-Fed Machine

The brushless doubly-fed machine (BDFM) has prospect application in the wind energy conversion system (WECS) for its abilities of speed regulation and variable-speed constant-frequency. The decoupled control of the active and reactive power is crucial to the applications of the BDFM in WECS. The robust control strategy based on sliding mode theory is applied for the independent control of active and reactive power of the BDFM. The controller is designed through the Lyapunov stable theory to ensure the stability of controller and achieve the required control result. The effect of the proposed method is tested with the matlab/simulink software. Simulation results illustrate the good performance of the controller and proves the power control strategys feasibility.

Passivity-based control in wind turbine for maximal energy capture

The question of maximal energy capture in the nonlinear wind energy conversion system with stochastic wind variety is presented. This article adopted the two inputs, that is pitch angle and trigger angle. The control strategy was based on passivity theory and designed a control system with strong robust and favorable dynamic characteristic. This control system combined the maximal wind energy capture to system stability, adopting the methods of selecting appropriate steady state and damp rejecting. The simulation results showed the control strategy can capture the maximal wind energy for that wind energy conversion system which has the stochastic wind and parameter variety.

A phase synchronization control scheme for LCL-T type high-frequency current source in parallel connection

Summary Considering the applications of high voltage gate driving system and contactless power transmission, a current-based power distribution is adopted as a kind of replacement of voltage based high-frequency Alternating Current (AC) power distribution system. In order to implement high-frequency current source, an LCL-T resonant inverter is examined with constant current characteristic and high conversion efficiency. First, the resonant topology is studied as a high-frequency power source, including circuit principle, operational cycle analysis, and AC analysis. The effective control and high conversion efficiency are both achieved by LCL-T resonant inverter. Second, the phase angle control scheme is explored to improve the synchronization performance in parallel system formed by multiple of LCL-T resonant inverters. Lastly, a prototype of parallel system is evaluated by simulation and experiment results, both of which are constructed by two resonant inverters with rated peak current of 2 A, rated output frequency of 30 kHz, and rated output power of 100 W. The experimental results in accordance with simulation prove that the better phase synchronization of output currents is achieved by the phase angle control. Hence, the high-frequency resonant topology and phase control scheme are a feasible realization of current source that can be used to feed current-based high-frequency power distribution system. Copyright

Passivity-based control of linear switched reluctance motors

Abstract In this paper, a non-linear controller for linear switched reluctance motors (LSRMs) is developed by utilizing their properties and the energy dissipation theory. As the electrical time constant is much smaller than the mechanical time constant, the whole LSRM driving system can be treated as a two-time-scale system. It is then decomposed into an electrical subsystem and a mechanical subsystem, which are interconnected by negative feedbacks. Controllers for these two subsystems are designed to guarantee that both systems are passive. Because a system consisting of two passive subsystems connected through negative feedbacks is still passive as a whole, stability of an LSRM driving system can be achieved at system level. The proposed control strategy is characterized by a simple structure and easy implementation. Experimental results are also provided to prove the effectiveness and robustness of the proposed position control for LSRM.

A Voltage-Feed High-Frequency Resonant Inverter With Controlled Current Output as a High-Frequency AC Power Source

A current-based power distribution is presented for the applications of high-frequency ac power distribution system (PDS). Comparing with the traditional voltage-based counterpart, the current-based system can be applied into some specific applications, such as high-voltage gate-driving system, contactless power transmission, etc. A modified resonant topology based on LCL-T tank is proposed to implement high-frequency current source. The effective magnitude control and high conversion efficiency are both achieved. First, the proposed topology is examined with circuit principle, operational cycle analysis, and soft-switching description. Second, the phase-shifted control scheme is explored to calculate the equivalent resonant capacitor of LCL-T resonant tank, as well as the relations between current gain ratio and phase-shifted angle control are discussed in depth. Finally, the simulation model and experiment prototype are implemented with rated peak current of 2 A, rated output frequency of 30 kHz, and rated output power of 50 W. The experimental results in accordance with simulation prove that the constant current characteristics are maintained with high conversion efficiency. Hence, the proposed circuit topology and control scheme are a feasible realization of current source that is used to feed high-frequency PDS.

Experiments in the Position Detection of Linear Switched Reluctance Motor

Position detection is very important in operation of linear switched reluctance motors (LSRMs). With increasing application of LSRMs, the position detection techniques would get more and more attention. In this paper, a position detection scheme is proposed for LSRM. In the scheme, the position is estimated by the injection of a series of small current into phase winding and measurement of the increase of phase current. The preliminary experiments in position detection are performed on the proposed LSRM. The experimental results confirm that the scheme is effective for position detection of LSRM.