Power supplies used on the electric power environment test process for electronic products and audio-amplifiers are required to generate arbitrary ac voltage waveforms in the wide frequency range. Traditionally, analogue amplifier technologies have been used for those application even though those have the disadvantages of low-efficiency, bulky in volume, and heavy in weight. Recently, however, research on the arbitrary waveform power generator becomes to be attractive among power electronics engineers, because the audio amplifiers utilizes the D-Mode switching technologies have been move into the market. This paper presents an arbitrary ac power generator utilizes a novel instantaneous waveform control method for a single-phase voltage source PWM inverter. A remarkable feature of this control method is that an adaptive frequency band-pass filter based on a rotation frame transformation and a command generator on the rotation frame is used. The proposed method can suppress the resonance caused by the LC filter at the output line, and hence it enables to generate a rectangular voltage waveform without overshoot. The command generator generates both an instantaneous frame angle and accurate voltage commands on the rotating frame from one an analogue signal. The effectiveness of this method is verified through 500W experimental set-up.
This paper introduces a takeoff and landing control technique related to a helicopter. The presented control system consists of a small toy electrically-powered helicopter for indoor flights, a flight base under which a focre sensor is set, and a helicopter control terminal which is connected to a system controller. The force sensor use is intended to realize soft takeoff and landing control. When the helicopter stands on the base, the force sensor outputs lift force data corresponding to the weight of the helicopter. As the operational voltage rises, the helicopter almost takes off from the base. Concurrently, the forse sensor output closes to 0. Thus, if the system controller controls the voltage arbitrarily, it is expected to realize the soft takeoff and landing control. This paper introduces the design process including modeling based on ststem identification technique, and shows the simulation and experimental results of the lift force control.
It is necessary for secure commercial train services to keep the contact wires in a regular condition. Most of the contact wires are inspected by the special dedicated train set for exclusive use of measurement, such as Doctor Yellow. However it is expected to develop the inspection system using normal passenger trains and normal business operation hour, without the expensive special inspection train set. Here we developed original and compact inspection system installed on the commercial bullet train of KYUSHUSHINKANSEN. This system measured the contact points of trolley and pantograph by using image processing which acquires the sequential images of the pantograph circumference during a high-speed run with cameras installed on the narrow limits of the train roof. This report describes the image processing procedures and some measurement result of the pantograph height and contact point deviation.
There is no doubt that Hybrid Electrical Vehicle can preserve the environment. These vehicles have several electrical power sources. The power flows among these sources are controlled generally using DC/DC converters. Therefore the DC/DC converter is the important device in HV. This paper shows the method how to reduce the inverter device current of the Multi-Functional Converter System (MFCS) in our laboratory. The MFCS consists of a motor, inverters and additional wires except of DC/DC converters. The MFCS can realize controlling the power among several AC or DC electrical power sources besides controlling motor torque. The characteristic of this MFCS in this paper is that the MFCS has two three-phase star connected coils in one motor. The proposed method is realized using the characteristic. This paper shows the validity of the proposed method using the experiment examinations.
This paper develops a probe for measuring the high frequency grounding potential and demonstrates its effectiveness. The developed probe is applied to a motor drive system and measures a potential difference between a grounding terminal and the motor frame connected by a grounding conductor. Moreover, this paper attempts to visualize noise propagation in a grounding system. An experimental system is constructed on a lattice-shaped ground plane. A three-phase cable stretched on the ground plane connects between a common-mode voltage source and a motor, and the motor frame is earthed to the ground plane. In experiment, the developed probes detect 25-point potentials, and reconstructing these 25 waveforms makes it possible to visualize noise propagation. In addition, influence of a common-mode choke upon the noise propagation are shown experimentally.
This paper presents principle and basic characteristics of a novel linear synchronous motor based on “half-wave rectified self excitation principle”. The field winding is short circuited through a diode and the armature winding is conventional 3-pahase windings. If the amplitude of the balanced 3-phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at bias frequency and moves at synchronous velocity. This pulsating magnetomotive force induces the electromotive force with bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode of the field winding. In this paper, we design and build the experimental machine and confirm the basic characteristics. We also deduce the performance equations and investigate on the thrust ripple reduction.
An improved configuration of SC coils, whose end coils have small size is studied to reduce their leakage flux. This paper examines the harmonic characteristics when the improved configuration of SC coils applies to the 120-degree coil pitch ground coil. An adequate combination of length and m.m.f. in the end coils can provide proper performance of harmonics and basis.
Chip mounters and surface mount device (SMD) inspection systems use image processing techniques for the placement of SMDs onto printed circuit boards (PCB) and the inspection of SMDs. Such techniques require the part shape data which define the shape of SMDs; however, the creation of this data is currently not automated. The goal of this paper is to make a system that generates part shape data automatically by processing images of SMDs. There are several target parts, such as IC, BGA (ball grid array), chips, and connectors, etc., for which data can be generated. In this paper we will focus on generation of data for IC parts.
New modeling of a synchronous reluctance motor SynRM which has non-linear magnetic characteristics is proposed. And a control method of the SynRM using the new model is developed. The new model is based on the inductance data table or the flux linkage data table which is calculated with the flux linkages of the SynRM at each current (id, iq). Detailed calculation method of the inductances is described. The calculated torque TA with the inductance data table is compared with the torque Tfem which is calculated by FEM and the difference is less than 5% at the rated torque. Therefore the accuracy of the new model is certified. And the same method is applicable to an interior permanent magnet synchronous motor IPMSM. The high performance motor control is realized. The exact current commands (id, iq), the exact voltage feed-forward commands (FFd, FFq) and the adaptive current loop gain (Gd, Gq) are obtained using the FEM data of the motor.
We are developing a gradationally controlled voltage inverter without output transformers for LSM in the Maglev Line. In this paper, it is first demonstrated that the gradationally controlled voltage inverter can suppress current waveform distortions with PWM control even at low frequencies in an experimental inverter model. Furthermore, we propose an active cancellation method for the zero-sequence voltage which adjusts the sum of the three-phase voltages to zero giving the advantages of a small-step and flexible output voltage. We also demonstrate that the zero-sequence current was reduced to 10% in the inverter model with the active cancellation method under the experimental condition that the output filter inductance was 2mH, 1/25 the inductance of the common filter in the Yamanashi Maglev system.
A new contactless power transfer system using series and parallel resonant capacitors is described. If the primary series resonant capacitor and the secondary resonant capacitor are set proper values, the equivalent circuit of the transformer with these capacitors becomes very simple at the resonant frequency. Ignoring the winding resistance and the core loss, the equivalent circuit is the same as an ideal transformer. Therefore the circuit analysis is easy, and if the input voltage is constant, the output voltage is also constant regardless the output current. The paper describes the determination of the series and the parallel capacitor values, the derivation of the equivalent circuit and the test results which shows the usefulness of the new contactless power transfer system.
In order to reduce costs of inverters for home electrical appliances using the PMSM, the AC current sensor-less control is required as well as the position sensor-less control. This paper proposes a PWM technique suitable for calculating AC currents from sampled DC current data in the one-shunt system, which is one of the AC current sensor-less methods. The proposed PWM technique using a triangle carrier wave leads to the dc current sampling at near the top and bottom of the carrier wave, and AC current calculation within one cycle of the carrier under normal conditions. To reduce errors in the AC current calculation caused by the PWM current ripple, the current ripple waveforms are calculated from the instantaneous inverter output voltages and used for the compensation. The principles of the PWM technique and the AC current calculation are explained, as well as experimental results.
This paper describes a bi-directional isolated dc/dc converter having a high-frequency transformer with a unity turn ratio, where the input and output dc voltages are different from each other. Theoretical analysis reveals that power loss in the dc/dc converter, as well as peak current flowing in the high-frequency transformer and auxiliary inductors, imposes limitations on the maximum transferable power. The 10-kW, 20-kHz dc/dc converter designed and constructed in this paper is operated with one dc voltage fixed to 320V and the other ranging between 180V and 360V without excessively increased power loss. The effect of the so-called “dead time” on the operating performance is also discussed in this paper. Such wide range of dc voltage may bring about a various application fields to the dc/dc converter.
This paper examines the cogging torque of permanent magnet (PM) motors resulting from the asymmetry property of the magnetic poles. Starting from the theoretical analysis of motor internal magnetic energy, we indicate that the pulsation number per revolution of the above-mentioned cogging torque component can be expressed as the multiple of the number of slots. We show the condition that the above-mentioned cogging torque component is generated as the relation between the MMF spatial distribution mode and the motor design parameters; the number of poles and the number of slots. We propose a motor quality prediction method from the viewpoint of the cogging torque resulting from the asymmetry property of the magnetic poles before the rotor is set into the stator—the magnetic flux density around the rotor is measured first, the measured value is squared, and then the componential analysis is made by DFT. The cogging torque amplitude is predicted by the content rate of the causal asymmetrical component. The effectiveness of the proposed method was confirmed experimentally. The verification motor has 32 poles and 36 slots, which is sensitive to the asymmetry property of the magnetic poles.
This paper presents an approach to Genetic Algorithm (GA)-based computer-aided autonomous electromagnetic design of 2-phase Switched Reluctance Motor drives. The proposed drive is designed for compressor drives in low-priced refrigerators as an alternative to existing brushless DC motors drives with rare-earth magnets. In the proposed design approach, three GA loops work to optimize the lamination design so as to meet the requirements for the target application under the given constraints while simultaneously fine-tuning the control parameters. To achieve the design optimization within an acceptable CPU-time, the repeated-calculation required to obtain fitness evaluation in the proposed approach does not use FEM, but consists of geometric flux tube-based non-linear magnetic analysis and a dynamic simulator based on an analytical expression of the magnetizing curves obtained from the non-linear magnetic analysis. The design results show the proposed approach can autonomously find a feasible design solution of SRM drive for the target application from huge search space. The experimental studies using a 2-phase 8/6 prototype manufactured in accordance with the optimized design parameters show the validity of the proposed approach.