Self-tuning control strategies have been developed for systems with uncertainties. However, owing to the undesirable reliability of the parameter estimation, they have not been hardly employed for real systems. In this paper, two self-tuning control techniques which enable us to implement for real systems are introduced. Furthermore, the effectiveness of them is discussed by employing for real chemical processes.
An effective system control method is presented for applying a three-phase current-source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt-type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a two-dimensional deadbeat control scheme is applied to APF current control. Further more, in order to cancel both the delay in the two-dimensional deadbeat control scheme and the delay in DSP control strategy, an adaptive Line Enhancer (ALE) is introduced in order to predict the desired value of three sampling periods ahead. ALE has another function of bringing the robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be reduced as much as possible compared to the case that ideal identification of controlled system could be made. The experimental results obtained from the DSP-based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low.
This paper presents a novel prototype of lowered loss snubber circuit topology suitable for multilevel voltage source inverter and rectifier for high power applications. The reduced power loss characteristics and voltage capability performances of the proposed voltage clamped snubber circuit are evaluated in comparison with conventional RCD snubber circuit designed for 4-level voltage source inverter using IGBTs on the basis of experimental results.
The ultrasonic motor has a heavy nonlinearity, which varies with driving conditions and possesses variable dead-zone in the control input associated with applied load torque. The dead-zone is a problem as an accurate positioning actuator for industrial applications and it is important to eliminate the dead-zone in order to improve the control performance. This paper proposes a new position control scheme of ultrasonic motors to overcome dead-zone employing model reference adaptive control (MRAC) with fuzzy inference. The dead-zone is compensated by fuzzy inference, and backstepping control performs accurate position control. As compared with MRAC which uses an augmented error, backstepping control can analyze a transient response. Mathematical models are formulated and experimental results are given to validate the proposed position control scheme.
A pulsed power supply with sag compensation using controlled gradational voltage to increase the flatness of output waveforms has been developed.The sag compensation circuit consists of compensation units connected in series. Each compensation unit consists of capacitances, diodes, and semiconductor switches. The capacitances of each unit are charged with different voltages by 2n (V0, 2V0, 4V0, ···). The compensation voltages, which has 2n-1 steps, is generated by switching the semiconductor switches of each unit in a binary sequence. Using this method, compensation voltage waveforms up to 6.2kV with 31 steps can be obtained with 5 compensation units. The sag compensation circuit has been adapted to a direct switch type pulsed power supply, which generates 7kV pulsed voltage with a pulse width of 700μs, thus realizing sag compensation.
Recently, attention has been paid to a voltage-sag compensator or the so-called dynamic voltage restorer (DVR), the power circuit of which consists of series and shunt converters. However, few discussions have been made on which is more practical for the DVR, a circuit configuration installing the shunt converter on the load side or that installing it on the supply side. This paper focuses on the circuit configuration installing the shunt converter on the load side, along with comparisons between the two configurations. As a result, the conventional configuration installing the shunt converter on the supply side requires a large-capacity energy storage device such as a dc link capacitor bank. On the other hand, the configuration characterized by installing it on the load side does not require any energy storage device in principle. Its operating characteristics and theoretical discussions are confirmed by computer simulation using the software package PSCAD/EMTDC.
This paper presents a method of minimizing the smoothing capacitor of the buck converter with isolated transformers and synchronous rectifiers, which is used for the low voltage-high current applications. The principle is to remove the ripple voltage by applying two-phase configuration of asymmetry switching. A detailed analysis is given using averaging method and cleared the operations of the circuit. Especially the smoothing capacitor can be shifted to the high voltage side, as a results the capacity is extremely lessened to be few μF. In this circuit, small capacitor of several hundred μF is necessary to use in the output (low voltage side). The capacitors in the primary and secondary sides being both small, the ceramic capacitors of low ESR are possible to use. From the experimental result, the efficiency of about 92% was obtained under the conditions of the input 140V and the output 1.5V/20A with the primary capacity of 0.33μF, the secondary capacity of 200μF and the switching frequency of 100kHz.
Several topologies of active-clamped DC-DC converters have been proposed before. This paper compares the common-mode noise properties of the conventional type using a pulse transormer for a gate driver and the common-source type proposed recently. Using a noise measuring system composed of LISN (Line Impedance Stabilization Network) and EMSCAN (Electromagnetic Scanning System), it was clarified that the common-source type has the superiority on noise reduction to the conventional one.
Normalized correlation template matching is applied to industrial image processing fields. However a target image area must be searched has the right potion and the same scale as a registered template image. This paper proposed a method to search a target image area that has free location and inclination in a gray-scaled image of printed circuit boards. Because electrical components and wires are set vertically and horizontally on a printed board, it is likely that edge directions are distributed vertically and horizontally a lot. The proposed method can estimate the inclination of a target image area by feature of edge directions and can reduce the computational cost for template matching. The inclination is measured by the edge direction histogram based on edge strength. The experimental results show that the inclinations of target image areas were measured with the averaged accurate of ± 2 degree and the computational cost was reduced to about 1% in comparison with the conventional method.
A magnetic vibration simulator is one of the most important test tools to evaluate the basic performance of superconducting magnet (SCM) for EDS maglev. In this paper, we propose a new magnetic vibration simulator which can also suspend car and bogie mounted with the SCMs to evaluate the performance of not only SCMs but also vehicle dynamics with levitation. This system is composed of magnetic exciting coils which can simultaneously suspend and vibrate the SCMs and inverters which can simultaneously control 3-phase and zero-phase currents. This paper describes the principle, analytical method and control method of this system, and using numerical example, the vehicle dynamics and the vibration response of SCM are revealed.
This paper proposes a practical approach to suppressing both shaft voltage and leakage current in an ac motor driven by a voltage-source PWM inverter. This approach is characterized by using a neutral line of the ac motor. A common-mode inductor is connected between the inverter and the motor. Moreover, a resistor and a capacitor are connected in series between the motor neutral point and the inverter negative dc bus. This unique circuit configuration makes the common-mode inductor effective in reducing the common-mode voltage appearing at the motor terminals. As a result, both shaft voltage and ground current are significantly suppressed with low cost. Over-voltages at the end of a cable can be suppressed by a normal-mode inductor and a resistor which are connected in parallel. The validity and effectiveness of the new approach are verified by experimental results from a 5-kVA laboratory system.
A permanent-magnet induction generator (PMIG) is a special induction machine self-excited from the inside of the squirrel-cage rotor by a permanent-magnet rotor (PM rotor). In order to evaluate the practical value of the PMIG, its steady-state performance is analyzed theoretically and experimentally. As a result, it was found that the PMIG exhibits good power factor and efficiency compared to a general-purpose induction generator (GPIG) of the same size.
In industrial robot arms, high speed and high accurate operation is required. However in case of high speed operation, it often arises high jerk, i, e., rapid change of acceleration. Jerk causes deterioration of control performance such as vibration of a tip of a robot arm. It is, therefore, important to reduce jerk during robot arm operation. In this research, spline interpolation is used to reduce jerk under torque and speed constraints. Effectiveness of the proposed method was assured by experimental results and simulation results of an actual robot arm.
This paper proposes the on-line parameter identification method of PM motor system including inverter. The d and q-axis inductances, phase resistance and voltage drop of inverter can be identified from the detected currents and voltage references at standstill. The validity of the proposed method is confirmed by experimental results.
In this paper, a novel full-bridge soft-switching phase-shifted PWM DC-DC power converter circuit is presented. A tapped inductor filter is implemented in the proposed converter topology to achieve soft switching commutation for the active power switches under wide load variation range, to minimize circulating current without using additional resonant circuit and/or auxiliary switching devices. The effectiveness of the proposed soft-switching DC-DC power converter is verified in experiment with 2kW-100kHz breadboard circuit using IGBTs.