Chang-Ming Liaw

A fuzzy controller improving a linear model following controller for motor drives

Since the dynamic response trajectory of a traditional fuzzy controller can not be quantitatively controlled, a fuzzy model following controller is proposed in this paper. In the proposed controller, an output feedback linear model following controller (LMFC) is first designed according to the roughly estimated plant model to let its response follow the output generated by a reference model. Then a model following error driven control signal is synthesized such that good model following characteristics can be preserved at various operating conditions. The proposed controller is applied to the speed control of an induction motor drive. Dynamic signal analysis of the model following behavior is made and the procedure for constructing the control algorithms is described in detail. The performance of the drive and the effectiveness of the proposed controller are demonstrated by some simulated and experimental results. >

Development of a Compact Switched-Reluctance Motor Drive for EV Propulsion With Voltage-Boosting and PFC Charging Capabilities

This paper presents a compact battery-powered switched-reluctance motor (SRM) drive for an electric vehicle with voltage-boosting and on-board power-factor-corrected-charging capabilities. Although the boost-type front-end DC/DC converter is externally equipped, the on-board charger is formed by the embedded components of SRM windings and converter. In the driving mode, the DC/DC boost converter is controlled to establish boostable well-regulated DC-link voltage for the SRM drive from the battery. During demagnetization of each stroke, the winding stored energy is automatically recovered back to the battery. Moreover, the regenerative braking is achieved by properly setting the SRM in the regenerating mode. The controls of two power stages are properly designed and digitally realized using a common digital signal processor. Good winding current and speed dynamic responses of the SRM drive are obtained. In addition, the static operation characteristics are also improved. In the charging mode, the power devices that were embedded in the SRM converter and the three motor-phase windings are used to form a buck-boost switch-mode rectifier to charge the battery from utility with good power quality. All constituted circuit components of the charger are placed on board, and only the insertion of power cords is needed.

Design and implementation of a fuzzy controller for a high performance induction motor drive

A limit-cycle controlled induction motor drive with a fuzzy controller has been designed and implemented. The torque and flux of the proposed drive system are regulated by the limit-cycle control technique. It follows that very quick torque response can be achieved. Since the dynamic model of this type of drive system is not easy to obtain, a fuzzy controller was developed and used in the speed control feedback loop to obtain good dynamic rotor speed response. The fuzzy algorithms in the proposed controller are systematically found from intuition and experience about the drive systems. The experimental results indicate that good dynamic speed performance can be achieved by the proposed controller. Moreover, since the rotor parameters are not needed in the implementation of the drive system, and due to the inherent feature of high adaptive capability possessed by the fuzzy controller, the performance of the controller drive system is rather insensitive to the parameter and operating condition changes. >

On the Design of Power Circuit and Control Scheme for Switched Reluctance Generator

The establishment and control for a switched-reluctance generator (SRG) are presented in this paper. First, the switching behavior and the DC-link ripple characteristics of a SRG are studied. Accordingly, its circuit and control models are established. And the power circuit components are properly designed to minimize the DC-link voltage ripples caused by commutation and pulsewidth modulation switching. Second, the quantitative voltage feedback control of the SRG system considering the effects of voltage ripples is made. In this issue, a unified approach is developed to estimate the plant dynamic model parameters from measurements. Then conversely, the feedback controller is designed according to the prescribed regulation voltage control specifications. Third, a dynamic commutation shift controller (DSC) is devised to enhance the voltage control performance of a SRG. As the voltage feedback control is failed when winding current becomes single-pulse mode, the proposed DSC is actuated automatically. The turn-on and turn-off angles are dynamically and automatically shifted to assist voltage feedback regulation control. More stable and better regulation control performance can be obtained. Finally, the energy conversion efficiency improvement via static commutation shift under static operation is evaluated experimentally. Theoretical bases of the proposed control approaches are derived, and their effectiveness is demonstrated by some simulation and measured results.

Adaptive positioning control for a LPMSM drive based on adapted inverse model and robust disturbance observer

The adaptive robust positioning control for a linear permanent magnet synchronous motor drive based on adapted inverse model and robust disturbance observer is studied in this paper. First, a model following two-degrees-of-freedom controller consisting of a command feedforward controller (FFC) and a feedback controller (FBC) is developed. According to the estimated motor drive dynamic model and the given position tracking response, the inner speed controller is first designed. Then, the transfer function of FFC is found based on the inverse model of inner speed closed-loop and the chosen reference model. The practically unrealizable problem possessed by traditional feedforward control is avoided by the proposed FFC. As to the FBC, it is quantitatively designed using reduced plant model to meet the specified load force regulation control specifications. In dealing with the robust control, a disturbance observer based robust control scheme and a parameter identifier are developed. The key parameters in the robust control scheme are designed considering the effect of system dead-time. The identification mechanism is devised to obtain the parameter uncertainties from the observed disturbance signal. Then by online adapting the parameters set in the FFC according to the identified parameters, the nonideal disturbance observer based robust control can be corrected to yield very close model following position tracking control. Meanwhile, the regulation control performance is also further improved by the robust control. In the proposed identification scheme, the effect of a nonideal differentiator in the accuracy of identification results is taken into account, and the compromise between performance, stability, and control effort limit is also considered in the whole proposed control scheme.

Control of indirect field-oriented induction motor drives considering the effects of dead-time and parameter variations

A speed controller that considers the effects of system dead time and parameter variations is presented. An indirect field-oriented induction motor drive is implemented, and its dynamic model is found, using a stochastic approach. A two-degree-of-freedom speed controller is designed to match the prescribed speed command tracking and load regulating specifications. Since the performance of the closed-loop controlled plant is greatly influenced by the presence of the inherent system dead time and parameter variations during wide-range operations, a dead-time compensator and a model-following controller are proposed to enhance the robustness of the two-degree-of-freedom speed controller. The simulated and experimental results show that good control performance both in speed command tracking and load regulating characteristics is achieved. >

Establishment of a Switched-Reluctance Generator-Based Common DC Microgrid System

This paper presents a dc microgrid including a switched-reluctance generator (SRG) with isolated boost dc-dc converter, a battery energy storage system, and a single-phase three-wire (1P3W) load inverter for generating ac 220/110 V 60-Hz outputs. The 400-V dc grid is established by the SRG with dc 48-V output followed by a current-fed push-pull (CFPP) dc-dc converter. The robust commutation and dynamic control schemes are developed for the SRG to have excellent output performances. For providing the domestic load power sources, a 1P3W transformerless 220/110 V inverter is established. A master and slave robust control schemes are proposed to yield balanced sinusoidal output voltage waveforms in both voltage outputs under varying load conditions. To improve the dc grid power supporting reliability, a battery energy storage system with bidirectional buck-boost interfacing converter is established. It can support the common dc bus voltage immediately when the main power source fault occurs. Conversely, the battery bank can be charged from the common dc bus through the same converter. Particularly, an auxiliary charger formed by a flyback switch-mode rectifier is equipped to allow the battery to be charged from the plug-in utility power as the long duration of microgrid fault occurs. Normal operation and good operating performance of the established microgrid are verified experimentally.

Analysis, design, and implementation of a random frequency PWM inverter

Random pulse width modulation (RPWM) approaches can make the harmonic spectrum of inverter output voltage be continuously distributed without affecting the fundamental frequency component, and thus the acoustic noise and mechanical vibration of an inverter-fed AC motor drive are greatly reduced. However, the analysis and design of the RPWM mechanisms are generally not so trivial for practical engineers that their applications are limited. In this paper, a random frequency PWM (RFPWM) inverter and its practical design procedure are presented. First, the effects of the attributes of a random signal on the inverter output harmonic spectrum distribution characteristics are analyzed using an intuitive concept, then based on which, the quantitative design. Simulink simulation and implementation of the proposed RFPWM inverter are introduced. The proposed RFPWM inverter is employed to power an indirect field-oriented induction motor drive. The simulated and measured results indicate that the uniform random distribution of inverter output harmonic spectrum and thus smaller acoustic noise and mechanical vibration are obtained by the proposed RFPWM scheme.

An Integrated Driving/Charging Switched Reluctance Motor Drive Using Three-Phase Power Module

This paper develops an integrated driving/charging switched reluctance motor (SRM) drive for electric vehicles using off-the-shelf three-phase intelligent power modules (IPMs). Five legs of two IPMs are employed to construct the four-phase SRM modified Miller converter. Moreover, its front-end dc/dc boost converter is formed by the remaining one leg to boost the dc-link voltage from a battery. Proper current and speed control schemes are designed to yield satisfactory driving performance. In particular, the performance under higher speed is enhanced by the boosted dc-link voltage and the advanced shift of commutation instant. In idle case, some imbedded IPM power devices and SRM windings are arranged to form a buck-boost type or a buck-type switch-mode rectifier (SMR) for charging the battery from a utility with good charging control characteristics and a line drawn power quality. The rating derivations, performance analyses, and controller designs for these two SMRs are performed in detail. All constituted circuit components of the charger are naturally placed onboard; only the insertion of a power cable to the ac source socket is needed. A common digital signal processor is used to realize all control schemes fully digitally, and their control performances are demonstrated experimentally.

Adaptive speed control for induction motor drives using neural networks

In this paper, the adaptive speed control of induction motor drives using neural networks is presented. To obtain good tracking and regulating control characteristics, a digital two-degree-of-freedom (2DOF) controller is adopted and a design procedure is developed for systematically finding its parameters according to prescribed specifications. The parameters of the controller corresponding to various drive parameter sets are found off-line and used as the training patterns to estimate the connection weights of neural networks, Under normal operation, the true drive parameters are real-time identified and they are converted into the controller parameters through multilayer forward computation by neural networks. The parameters of the 2DOF controller can be adapted to match the desired specifications under various operating conditions. >