This paper proposes a novel robust design method of the full-order observer for vector controlled induction motors. The full-order observer has been widely employed to estimate rotor flux, but pole location for robust flux estimation against parameter deviations has not been clear unfortunately. In this paper, robust flux estimation problem is regarded as a phase shaping problem of a transfer function because it is the most important for the vector control to suppress axis deviation. Accordingly, the proposed design method utilizes γ-positive real problem, gain-scheduled H∞ control and linear matrix inequality technique so that axis deviation might be suppressed against parameter deviations at all operating point. Robust performance of the proposed method is evaluated by the frequency response function. Finally, feasibility and effectiveness of the proposed method are shown by experimental results.
In this paper, an estimation method of both torque coefficient and moment of inertia of the windmill by using genetic algorithm is proposed. Generally, the torque coefficient is dependent on the shape of the windmill and is represented as a nonlinear function of the tip speed ratio. To simulate the nonlinearity, the torque coefficient is split into the m areas with respect to the tip speed ratio and is approximated by a piecewise linear equation in each area. The gains of the piecewise linear equation in each area and the moment of inertia are regarded as the gene and adjusted by the genetic algorithm so that the estimated windmill speed and acceleration correspond to the actual values. The results demonstrate the effective of the proposed scheme for estimation of the windmill parameters.
H∞ robust controllers are mathematically designed in the frequency domain using loop-shaping techniques under the given control characteristics. In the design process, however, knowledge and/or experience is generally required to define the appropriate weighting functions which satisfy the desired control performance. This prevents the controller design from being simple and cost effective. The paper proposes a novel autonomous design strategy for the weighting functions in the H∞ compensator design, where GA can optimize both structuring and parameterization of the weighting functions in order to achieve the specified control performance in the time domain. The effectiveness of the proposed design was verified by numerical simulations and experiments using a prototype.
Recently, it is popular to study about ER fluid in a field of mechatronics and fluid mechanics. An ER fluid is one of the smart fluid, and it has the character that the apparent viscosity can be controlled according to strength of an applied electric field. We also have already developed of the one shaft type ER clutch using a homogeneous ER fluid that is one of the ER fluids. The homogeneous ER fluid has a character that the particle does not subside and the gap between electrodes can be narrowed due to be able to get the shearing stress in the same electric field. In addition, it also has a character that its viscosity is susceptible to the temperature variation. However, there are no reports about the temperature characteristics for the clutch using the homogeneous ER fluid. In this paper, we study about thermal characteristics of the clutch using the homogeneous ER fluid. First, we discuss about the torque performances of the homogeneous ER clutch for the increasing its temperature. Here, it was found that the output torque of the clutch depends on the temperature variation. Next, we also discuss about an exothermic element of the homogeneous ER fluid given by the clutch. The result of experiment and simulation clearly shows that the most of exothermic elements of the homogeneous ER fluid is caused by the dissipation of viscosity energy in the fluid. As a result, suitable using method for the homogeneous ER clutch seems reasonable to drive the clutch with low rotating speed for the short time.
A novel object transfer system named “Magic Carpet” composed of linear actuator array and driven by autonomous decentralized type control algorithm is proposed. An object is manipulated by a large number of contact points with many actuators, which differs from conventional systems like belt conveyor. In this paper, the control algorithm for such “distributed manipulation” is proposed. Due to recent development of micromachine technology, distributed manipulation becomes more important. This system has a big advantage in its fault tolerance because it has a lot of actuators with poor performance to move a large heavy object. However, it has a serious wiring problem to be solved and homogeneous structure should be introduced because of a large number actuators. To solve these problems, “combined control of central /autonomous decentralized algorithms” is proposed and evaluated by computer simulation and experiment.
This paper presents a fully digital direct torque control (DTC) scheme for a five-phase induction motor based on a 32-bit floating-point TMS320C32 Digital Signal Processor (DSP). The similarities and differences of DTC of the five-phase and three-phase induction motors are analyzed and investigated. In the case of the five-phase induction motor, DTC method has unique advantages. Compared with 8 voltage vectors of the three-phase induction motor drive system, DTC of the five-phase motor drive system has 32 space voltage vectors with different magnitudes. The increased number of the space voltage vectors enables DTC of the five-phase induction motor greater flexibility in selecting the inverter switching states, and achieves a better control of the stator flux and torque. Simulation and experimental results validate the theoretical analysis, and further demonstrate that DTC of the five-phase induction motor yields better performance than that of the three-phase induction motor.
Since maximum power point tracking (MPPT) control is useful to realize an efficient PV system, many papers on MPPT scheme have been proposed. In most cases, they basically depend on so-called mountain climbing method which depends on the information of output power of PV array. Authors previously proposed a new MPPT control scheme for PV system connected in parallel with the ac system line. The system also depends on mountain climbing method. However, it needs no sensors or calculation for PV array power detection, and utilizes an interior control signal of dc link voltage control loop itself. For this reason, system response and stability greatly depend on the main circuit and control system parameters. This paper shows system design to ensure well-damped stable operation and fast response based on system analysis. Response of the experimental system has been proved fast enough for practical use.
This paper proposes a new speed servo system of PM motor without current sensor, which is constructed by the current simulator of PM motor. The proposed speed servo system is simple and economical. The sensor of the proposed system is only a position sensor such as an encoder. Hence, the proposed speed servo system has little influence of the switching noise of PWM inverter. Moreover, the resolution of proposed current simulator can be higher than of the conventional actual current feedback system. In this paper, the experimental results point out that the proposed current sensorless speed servo system has the desired current and speed response. The current waveform of the proposed system is smooth and clean. Moreover, this paper proposes a new identification algorithm of motor resistance Ra and main flux Φfa by using only position sensor.
Conventional unmanned helicopters are used to spray agricultural chemicals and take aerial photographs. In the near future, the aircrafts are expected to be used for a wide array of activities, such as rescuing and fire fighting. Then, an autonomous flight using several sensors typified by a global positioning system (GPS) is highly expected. In this paper, first, system identification experiments for a large-scale unmanned helicopter are carried out to obtain a numerical model of aircraft dynamics. The attitude error of the helicopter is compensated by a stability augmentation system that permits the experiments during the flight. System identification results are shown on the dynamics using the measured input and output data. Next, the position control systems based on the _??_∞ control theory is constructed by using the identified model. Finally, the position control experiments suggest that the proposed modeling and design approach is effective enough for practical applications.
In order to share environment with human for a mobile robot, it is necessary to avoid dynamic obstacles like human. Then, in this paper, an avoidance of an obstacle which governed by probabilistic equation, is realized. The paper proposes the probabilistic potential field adopted in the trajectory planning. It is possible to take a sudden change of an environment into account in the proposed method by assigning priority to the latest data. The numerical and experimental results show viability of the proposed method.
This paper describes a quasi-resonant ZVS-PWM high frequency inverter using SITs under fixed frequency mode. It is designed so as to operate at soft switching PWM condition in order to minimize switching losses and electrical dynamic stresses in its switching power devices over wide output power regulation ranges. The operating principle of this inverter and its PWM controlled power regulation procedure are presented for induction heating. Its performances are evaluated and discussed from a practical point of view.
This paper presents the motor shaft current suppression scheme which is based upon three-phase voltage source inverter with an auxiliary quasi-resonant dc link snubber. The soft commutation operation in steady state of the active auxiliary quasi-resonant dc link snubber incorporated into the voltage source inverter treated here is described and the effectiveness on the motor shaft current suppression is substantially demonstrated on the basis of the experimental results.
This paper proposes high frequency electronic ballast for HID lamps with a hot restarting circuit. The proposed circuit is composed of voltage source half bridge inverter, immittance conversion circuit, parallel LC resonant circuit, HID lamp, and igniter. The voltage source is converted into current source and vice versa by the effect of immittance conversion circuit. The ballast supplies not only high cold start voltage to the lamp, but also stable current during lamp operation. The igniter is also capable of the supplying the high voltages required to discharge a hot lamp.
In this work, the authors suggest the use of a new waveform of exciting current for microstep drive of a two-phase stepping motor. In the derivation of the waveform, maximization of torque produced by the motor and equalization of the intervals of microsteps are taken into account. The advantage of this driving method is demonstrated by measuring the positional error, the speed-resonance characteristic and the speed-torque characteristic.