Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

A new nonlinear disturbance observer (NDO) for robotic manipulators is derived in this paper. The global exponential stability of the proposed disturbance observer (DO) is guaranteed by selecting design parameters, which depend on the maximum velocity and physical parameters of robotic manipulators. This new observer overcomes the disadvantages of existing DOs, which are designed or analyzed by linear system techniques. It can be applied in robotic manipulators for various purposes such as friction compensation, independent joint control, sensorless torque control and fault diagnosis. The performance of the proposed observer is demonstrated by the friction estimation and compensation for a two-link robotic manipulator. Both simulation and experimental results show the NDO works well.

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A nonlinear disturbance observer for robotic manipulators

A torque sensorless control for a multi-degree-of-freedom manipulator is described. In the method, two disturbance observers are applied to each joint. One is used to realize a robust motion controller. The other is used to obtain a sensorless torque controller. A robust acceleration controller based on the disturbance observer is shown. To obtain the sensorless torque control, it is necessary to calculate the reaction torque when the mechanical system performs a force task. The calculation method for the reaction torque is explained. Then the method is expanded to workspace force control in the multi-degree-of-freedom manipulator. Several experimental results are shown to confirm the validity of the proposed sensorless force controller. >

Torque sensorless control in multidegree-of-freedom manipulator

A review of power converter topologies for wind generators

The speed regulation problem for permanent magnet synchronous motor (PMSM) servo system is studied in this paper. In order to optimize the control performance of the PMSM servo system, the predictive functional control (PFC) method is introduced in the control design of speed loop. The PFC-based speed control design consists of two steps. A simplified model is employed to predict the future q -axis current of PMSM. Then, an optimal control law is obtained by minimizing a quadratic performance index. However, it is noted that the standard PFC method does not achieve a satisfying effect in the presence of strong disturbances. To this end, an improved PFC method, called the PFC+ESO method, is developed. It introduces extended state observer (ESO) to estimate the lumped disturbances and adds a feedforward compensation item based on the estimated disturbances to the PFC speed controller. Simulation and experiment comparisons are made for these PFC methods and proportional-integral method with antiwindup control method to verify the effectiveness of the proposed methods.

Speed Control for PMSM Servo System Using Predictive Functional Control and Extended State Observer

Simple and high-performance path tracking control and force control based on an acceleration control are proposed. To realize the acceleration control, disturbance feedback is necessary. The disturbance observer whose inputs are a current reference to the power converter and a position signal by simple computation works as if it were a disturbance detector. The control poles of the observer are varied in accordance with the velocity of the motor for precise positioning. The proposed method was applied to the linear synchronous motor, which is used for direct drive linear motor, and was tested. Results are presented. >

Disturbance observer-based motion control of direct drive motors

The authors propose an inexpensive wind power generating system in this paper. Existing wind power generating systems are mostly of large capacity (over 100 kW) and high-priced (about 1000 USS/kW). Because of the erratic changes of wind power and of smoothing peak power, an AC/DC converter-fed battery system is recommended. Thus, one requires the exact rotating speed of generators (especially in the case of synchronous generators) to use AC/DC converters with high quality. These factors are increasing the cost of such systems. The authors adopt a compact permanent magnet type synchronous generator, which doesn't need exciting current, and a step-up/down buck-boost chopper to wind power generating system of a few kW output without position or speed sensor. In addition, they employ an inexpensive rectifier circuit using a diode bridge instead of an AC/DC power converter with PWM method. Using these methods, they achieve a simple and inexpensive wind power generating system.

A simple wind power generating system with permanent magnet type synchronous generator

Existing wind power generating systems are mostly of large capacity (over 500 kW output) and high-priced These systems require a wide area for construction. Therefore, we propose a small-scaled (about 5-10 kW output) generating system. This system has the advantage of system flexibility against the large one. But the small-scale system has a weak point of system efficiency. Then, we have to construct a simple and inexpensive system. Because of the erratic change of wind power, an AC/DC converter-fed system is recommended. Therefore, we adopt a compact permanent magnet type, synchronous generator which doesn't need exciting current, and step up/down buck boost chopper to wind power generating system without position or speed sensor. In addition, we employ an inexpensive rectifier circuit using a diode bridge instead of an AC/DC converter with a PWM method. Using these methods we achieve a simple and inexpensive wind power generating system. Furthermore, we propose a simple maximum power tracking control system with analog circuit and achieve aver 90% output of maximum power in any circumstance.

An improvement of performance for small-scaled wind power generating system with permanent magnet type synchronous generator

In this paper, the authors propose a method to obtain the compensation signal to suppress the vibration of the. motor frame by the repetitive control installing an online Fourier transform and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor (microphone) detected by a microphone placed close to the motor frame. The sensor is used only for the acquisition of the feedforward compensation data. Also presented is a new method of the feedforward compensation control adapting to change of operating point of the motor. The effectiveness of the proposed method is confirmed by experimental results.

Suppression control method for torque vibration of AC motor utilizing repetitive controller with Fourier transformer

In earlier papers, it has been reported that a fast and precise servo system, which has low-sensitivity to parameter variation and disturbance, can be realized with simple structure by using a high order disturbance observer. However, a clear and simple design method satisfying specifications for robust stability, influence of measurement noise, and relative stability has hardly been proposed. In this paper, we clarify the class of the robust servo system realized by adjusting the order of the disturbance observer and show design of an estimated disturbance feedback by the disturbance observer, which can represent a classical control approach. We apply this strategy to a design of a position servo system and realize the high performance robust servo system using the high order disturbance observer.

Muneaki Ishida

Papers

Disturbance observer-based motion control of direct drive motors

A simple wind power generating system with permanent magnet type synchronous generator

An improvement of performance for small-scaled wind power generating system with permanent magnet type synchronous generator

Suppression control method for torque vibration of AC motor utilizing repetitive controller with Fourier transformer

Analysis and classical control design of servo system using high order disturbance observer