The current paper is dedicated to present browser-based multimedia-rich software tools and e-learning curriculum to support the design and modeling process of power electronics circuits and to explain sometimes rather sophisticated phenomena. Two projects will be discussed. The so-called Inetele project is financed by the Leonardo da Vinci program of the European Union (EU). It is a collaborative project between numerous EU universities and institutes to develop state-of-the art curriculum in Electrical Engineering. Another cooperative project with participation of Japanese, European and Australian institutes focuses especially on developing e-learning curriculum, interactive design and modeling tools, furthermore on development of a virtual laboratory. Snapshots from these two projects will be presented.
The analysis and design of nearly unity power-factor and fast dynamic response of the modular three-phase ac to dc converter using three single-phase isolated SEPIC rectifier modules with minimized dc bus capacitor is discussed, based on power balance control technique. The averaged small-signal technique is used to obtain the inductor current compensator, thus resulting in the output impedance and audio susceptibility become zero, that is, the output voltage of the converter presented in this paper is independent of the variations of the dc load current and the utility voltage. The proposed system significantly improves the dynamic response of the converter to load steps with minimized dc bus capacitor for Distributed Power System (DPS). A 600W prototype modular three-phase ac to dc converter comprising three 200W single-phase SEPIC rectifier modules with the proposed control scheme has been designed and implemented. The proposed system is confirmed by experimental implementation.
This paper presents an excellent PWM method for power conversion circuits. The proposed method is called a Vector Frequency Modulation (VFM) in this paper. VFM does not belong to any conventional PWM methods. Although an idea of space voltage vector is employed in VFM, any traditional equations to calculate the periods of the voltage vectors are not used. The voltage vectors are classified into two groups, zero vectors and non-zero ones. Instead of the complicated equations, a very simple algorithm is employed in VFM. One vector period is fixed and the zero vectors are distributed among the non-zero vectors in the ratio determined by the command voltage or frequency. The behavior of VFM is performed in software and any modulation-wave oscillators, comparators and up-down counters are not needed. At first, a reversible chopper is modulated by VFM and a 2kW DC motor is driven by the chopper. The motor speed is regulated by modern control theory. Next, a three-phase inverter is modulated by VFM and a 2.2kW induction motor is driven by the inverter. Experimental results are shown to prove that VFM is actually useful for power conversion circuits.
We present a three-phase PWM converter without ac voltage and ac current sensors. The phase angle used in the control system is adjusted by using a PLL controller without sensing ac voltage. To prevent over-current at startup, the initial phase angle of the source voltage is estimated from the shunt current using a novel strategy. Furthermore, the phase currents can be reconstructed from the shunt current without any modification of PWM pattern. To reduce the effect of current ripple, the shunt current is sampled twice for every phase in one PWM period and the sample timings are carefully adjusted. All of the proposed control schemes can be implemented using a single chip microprocessor (SH7046, Renesas Tech.). Simulation and experimental results with a 5-kW prototype confirmed that the schemes worked well.
This paper proposes analysis a dead-time error voltage compensation method with a disturbance observer for vector control, and analyses the proposed method. The dead-time compensation is very important to improve performances in the low speed region. The proposed compensation method is composed in the d-q rotational frame with the disturbance observer. As a result, a disturbance transmission characteristic becomes same as a high-pass filter. Then a stability of the proposed controller is hardly affected by controller parameters. In this paper, the validity of analysis is confirmed by experimental results under some conditions. The experimental results are similar to analyzed characteristics and indicate a validity of the analysis results.
The dependence of forward voltage degradation on crystal faces for 4H-SiC pin diodes has been investigated. The forward voltage degradation has been reduced by fabricating the diodes on the (000-1) C-face off-angled toward <11-20>. High-voltage 4H-SiC pin diodes on the (000-1) C-face with small forward voltage degradation have also been fabricated successfully. A high breakdown voltage of 4.6kV and ΔVF of 0.04V were achieved for a (000-1) C-face pin diode. A 8.3kV blocking performance, which is the highest voltage in the use of (000-1) C-face, is also demonstrated in 4H-SiC pin diode.
A definition of the visual walking proposed by authors is that the robot autonomously walks by making decision based on the image feature motion. One of the achievements is “visual tracking walk”. In the past conference, authors proposed a hybrid control for “visual walking”. In this paper, the four vertexes of a square surrounding the red target in the image plane are selected as image features. Using such image features, the robot moves in front of the desired position. The rotation orientation of the robot is improved by the feature values caused by the walking motion. The proposed control law is verified by simulations and experiments.
This paper presents a current control design for switched reluctance motors (SRMs). The electric transfer characteristic of the motors is studied first. Their transfer function is brought out to be represented by a pure resistive component, which is not constant but varies depending on the motor current and speed. The current control design for SRMs follows the classical design technique used for dc machines, where the zero of PI controller cancels the pole of Ls+R. Because the transfer function of SRMs does not have any poles, an I controller is suitable for them. The integral gain should be adjusted in order to compensate the non-linearity, that is, the variation in the equivalent resistor of the SRMs' transfer function. The values of the integral gain are tuned and tabulated for the motor speed and current. Simulation and experiment demonstrate that the current and speed of the SRMs presents good responses without dependence on the motor speed and current.
In some motor applications, it is very difficult to attach a position sensor to the motor in housing. One of the examples of such applications is the dental handpiece-motor. In those designs, it is necessary to drive highly efficiency at low speed and variable load condition without a position sensor. We developed a method to control a motor high-efficient and smoothly at low speed without a position sensor. In this paper, the method in which permanent magnet synchronous motor is controlled smoothly and high-efficient by using torque angle control in synchronized operation is shown. The usefulness is confirmed by experimental results. In conclusion, the proposed sensor-less control method has been achieved to be very efficiently and smoothly.
This paper proposes a space voltage vector modulation (SVM) method for a speed servo system to obtain a quick current response. The proposed SVM method shortens the control lag time of the conventional SVM inverter. In addition, this proposed method is easily implemented of the hardware using a FPGA (Field Programmable Gate Array) because the proposed SVM equations is transformed into the expressions that hardly needs multiplication. By using the proposed SVM method, the servo system realizes a quick and stable current control with wide bandwidth. Moreover, by using PI controllers considering the voltage saturation and the torque limiter to the speed servo system, the servo system carries out a stable speed control on voltage saturation. Both the proposed SVM method and the PI controllers considering the voltage saturation are applied to a speed servo system of a vector controlled induction motor. The effectiveness of both the proposed SVM method and the PI controllers considering voltage saturation is verified by the experimental results.
This paper describes an unusual behavior detection system based on an omni-directional vision sensor as one of the important elements in realizing “Sensing and Robotic Support Room” for elderly people. Such support rooms are expected to be further developed in the future with the high performance to automatically recognize elderly people's actions and behavior patterns and detect the unusual patterns using some sensors and to support their daily motions using some robotic manipulator control systems. The proposed monitoring system using an omni-directional vision sensor automatically learns the daily behavior patterns and detects the unusual behavior patterns and actions using Bayesian Network approach. The Bayesian Network is constructed using image feature values such as the area and center of gravity values extracted from the captured image sequence and the respective behavior patterns are represented as the conditional probabilities. Unusual behavior patterns can be automatically detected based on the low generation probability values. Some experiments based on the investigation of elderly people's typical daily behavior patterns show the effectiveness of the proposed system.
This paper proposes a hysteresis regulator with a frequency characteristic, which reduces specific harmonic power in a direct power control system of a current-source PWM rectifier. The method virtually adjusts the hysteresis bandwidth in association with frequencies of the power pulsation; hence the regulator is capable to filter specific frequency components of the input current as well as the power. The paper describes a theoretical aspect of the proposed approach, and presents some experimental results of a particular case, where the 5th and the 7th harmonic input currents are mainly suppressed by eliminating the 6th harmonic component of the active power.
A power assist system for automobile slide doors that can provide comfortable operational feelings has been developed. The system incorporates a reference door model having preferable operational feelings. In order to follow virtual motion of the ideal door, both feedforward- and feedback-controllers are employed to drive a power assisting motor. Simulations and experiments have proved that the motion of the actual door corresponds well with that of the ideal door.