Tian-Hua Liu

Model-Free Predictive Current Control for Interior Permanent-Magnet Synchronous Motor Drives Based on Current Difference Detection Technique

A model-free predictive current control (PCC) of interior permanent-magnet synchronous motor (IPMSM) drive systems based on a current difference detection technique is proposed. The model-based PCC (MBPCC) of IPMSM requires knowledge of parameters such as resistance, q-axis inductance, and extended back EMF. This paper develops a new model-free approach that alleviates the need for excessive prior knowledge about the system and only utilizes the stator currents as well as the current differences corresponding to different switching states of the inverter. Despite the salient difference of the proposed approach, it adopts a measure similar to that in the MBPCC approach to obtain the next switching state of the inverter by minimizing a cost function. It is noteworthy that the proposed method is easy to implement due to its simplicity and free of any multiplication operation. For comparison purposes, a digital signal processor, TMS320LF2407, is used to execute the two aforementioned current control techniques. Several experimental results show that the proposed method can significantly improve the current-tracking performance.

Improvement of Matrix Converter Drive Reliability by Online Fault Detection and a Fault-Tolerant Switching Strategy

The matrix converter system is becoming a very promising candidate to replace the conventional two-stage ac/dc/ac converter, but system reliability remains an open issue. The most common reliability problem is that a bidirectional switch has an open-switch fault during operation. In this paper, a matrix converter driving a speed-controlled permanent-magnet synchronous motor is examined under a single open-switch fault. First, a new fault-detection method is proposed using only the motor currents. Second, a novel fault-tolerant switching strategy is presented. By treating the matrix converter as a two-stage rectifier/inverter, existing modulation techniques for the inverter stage can be reused, whereas the rectifier stage is modified by control to counteract the fault. However, the proposed techniques require no additional hardware devices or circuit modifications to the matrix converter. Experimental results show that the proposed method can maintain the motor speed with a maximum ripple of 2%-a fivefold improvement over the uncompensated system. The proposed method therefore offers a very economical and effective solution for the matrix converter fault tolerance problem.

Position Control of an Interior Permanent-Magnet Synchronous Motor Without Using a Shaft Position Sensor

This paper proposes a novel sensorless position control system for an interior permanent-magnet synchronous motor. In this paper, a novel rotor position/velocity estimation technique is proposed. This estimation technique only relates to the slopes of the stator currents and does not relate to the parameters or operating conditions of the motor. Neither an extra circuit nor an external high-frequency exciting signal is required here as compared to other position estimation techniques. In addition, the proposed estimator works well in transient, steady-state, and standstill conditions. As a result, the proposed method is very robust and useful. To improve the performance of the position-control system, an optimal controller is proposed. By using this controller, a fast transient response, good load disturbance rejection capability, and satisfactory tracking ability can be achieved. A digital signal processor, TMS-320-LF-2407, is used to execute the rotor position/velocity estimation, the current-loop control, the velocity-loop control, and the position-loop control. As a result, a fully digital position-control system is achieved. Several experimental results validate the theoretical analysis.

Position control of a sensorless synchronous reluctance motor

This paper presents a novel position control for a sensorless synchronous reluctance drive system. By measuring the three-phase currents of the motor, a rotor position estimator is achieved. Then, a velocity estimator is derived from the estimated rotor position by using a state estimating technique. The estimated velocity tracks the real velocity well. Next, a robust position controller is designed to improve the transient and load disturbance responses. By using the proposed estimating techniques and control algorithm, a high-performance sensorless synchronous reluctance drive is obtained. A digital signal processor, TMS-320-C30, is used to execute the estimating and control algorithms. No hardware circuit or external signal is added as compared with the traditional drive system with an encoder or resolver. To evaluate the performance of the position control system, a moving table is connected with the drive system. The drive system can precisely control the moving table. Experimental results show that the proposed system has good performance. Several experimental results validate the theoretical analysis.

Nonlinear adaptive-backstepping controller design for a matrix-converter based PMSM control system

This paper proposes a novel controller design for a matrix-converter based PMSM control system. A nonlinear adaptive backstepping controller is proposed to improve the speed and position responses of the PMSM control system. By using the proposed controller, the system can track both speed and position time-varying commands well. A satisfactory servo performance can be achieved. In addition, the realization of the controller is very simple. All of the control loops, including current-loop, speed-loop, and position-loop, are implemented by a 32-bit TMS320C40 digital signal processor. The hardware, therefore, is very simple. Several experimental results are shown to validate the theoretical analysis.

A High-Performance Sensorless Position Control System of a Synchronous Reluctance Motor Using Dual Current-Slope Estimating Technique

This paper proposes an adaptive sensorless position control system for a synchronous reluctance motor (SynRM). By using the proposed dual current-slope estimating technique, the rotor position of the SynRM can be precisely obtained. In addition, a comparison which shows that the proposed dual current-slope method has better performance than the traditional single current-slope method is discussed. To improve the transient responses and load disturbance rejection capability, an adaptive controller and a novel online self-tuning-gain state estimator are proposed here. A TMS-320F-28335 digital signal processor is used to execute the rotor position estimation, self-tuning-gain state estimation, adaptive control algorithm, d-q to a-b-c coordinate transformation, and PWM switching strategy. As a result, the hardware circuit is very simple. Experimental results show that the proposed system has satisfactory performance and good robustness. The estimated position error of the proposed dual current-slope estimating method can be reduced to 50% as compared to the traditional single current-slope position estimating method. Several experimental results are provided to validate the theoretical analysis.

Design and Implementation of an Online Tuning Adaptive Controller for Synchronous Reluctance Motor Drives

The paper proposes a new adaptive controller design for a synchronous reluctance motor drive system. In this paper, an online tuning adaptive controller, which is based on the least-mean-square algorithm, is proposed. The adaptive controller is constructed by using an adaptive model and an adaptive control. Both the adaptive-model parameters and the adaptive-control parameters are online tuned. A nonlinear programming optimization technique is used to improve the convergence rate of the online tuning method. By using the proposed method, the transient responses, load disturbance responses, and tracking responses of the drive system are improved. The experimental results show that the implemented drive system can perform a wide range in adjustable speed from 1 to 1800 r/min and a precise position control as well. A digital signal processor, TMS-320F-28335, is used to execute the adaptive current-loop, speed-loop, and position-loop controllers. Experimental results can validate the theoretical analysis and show the feasibility and correctness of the proposed method.

Modeling and torque pulsation reduction for a switched reluctance motor drive system

This paper presents a new method for analysis and design of a three-phase switched reluctance drive system. First, the mathematical models of a switched reluctance motor under an a-b-c stationary frame and a d-q synchronous frame are proposed. Next, two current command waveforms that produce a lower torque pulsation than traditional switched reluctance drives are discussed. Finally, some simulation and experimental results are presented to validate the theoretical analysis. This paper presents a new direction in analysis and control of a switched reluctance motor.

Adaptive backstepping PI sliding-mode control for interior permanent magnet synchronous motor drive systems

An adaptive backstepping PI sliding-mode control is proposed for speed control of the drive of an interior permanent magnet synchronous motor (IPMSM) subjected to load disturbances. First, a nonlinear model with uncertainties is derived for the IPMSM, and then an adaptive backstepping sliding-mode controller incorporating a linear load torque estimator is designed. Next, the parametric uncertainties of the model are handled with adaptive laws in the design of the controller. To attenuate the chattering problem without sacrificing the feature of the sliding-mode control, an adaptive Pi-saturation function is used to approximate the signum function within the boundary layer. Asymptotic stability of the proposed control method is proven by Lyapunov stability theory and Barbalats lemma. A digital signal processor, TMS320LF2407, is adopted to implement the proposed control scheme. The experimental results show that the proposed system can effectively reduce the chattering phenomenon and has fast transient response, good load disturbance rejection response, and good tracking response.

Design and Implementation of a Robust Controller for a Micro Permanent Magnet Synchronous Speed Control Systems

This paper proposes an Hinfin state feedback controller is used in the speed control for a micro permanent magnet synchronous motor. In addition, the genetic algorithms are used to determine the weighting functions of the Hinfin controller. An optical encoder with 100 pulses/revolution is used to achieve the rotor position of micro permanent magnet synchronous motor, which has fast response and good load disturbance rejection capability. The digital signal processor TMS320LF2407 is used as the control center to execute the estimation and control algorithms. Experimental results validate the theoretical analysis to show the correctness and feasibility of this dissertation.