An interior permanent magnet (IPM) motor drive system which has regenerating capability augmented by electric double-layer capacitors (EDLCs) is proposed. In the proposed system, EDLCs are arranged in series with batteries so that a lesser number of the EDLCs and batteries will be required. The proposed system has two bi-directional voltage boosters: one is for both the batteries and EDLCs to control the dc-link voltage of a PWM inverter and the other is for only the EDLCs and is used to control the energy flow from and to the EDLCs. In this paper, a strategy to control the energy flow to and from the EDLCs is explained and its effectiveness is confirmed by simulation and experimental results. Furthermore, the efficiencies of the voltage booster, inverter, PM motor, and whole system are measured for the system with the basic configuration, i.e., which consists of only one bi-directional voltage booster and PWM inverter. Then, the steady-state characteristics are determined. Finally, the efficiency of the voltage boosters in the proposed system is determined, and the advantage of the proposed PM motor drive system is discussed.
The power conversion efficiency of soft-switching inverter can be improved by using loss-less snubber commutation; however, the main switches of the inverter fail in zero-voltage turn-on when the output current is small. As a solution to this problem, adjustable dead time control that involves adjusting the dead time in a loss-less snubber commutation according to the magnitude of output current has been proposed. Adjustable dead time control achieves zero-voltage turn-on of the main switches of the inverter in a loss-less snubber commutation in the range of low output current; however, the inverter output current waveform is distorted. In this paper, we propose a scheme for adjustable dead time control with dead time compensation for soft-switching inverters. Moreover, the effectiveness of the proposed control scheme is verified by performing experiments. The results of the experiments reveal that when the proposed control scheme is adopted, the power conversion efficiency in the range of low output power improves up to about 3% and the THD is improved within 3%.
We propose a new design support system that can color illustrations according to a person's color preferences that are determined on the basis of the color patterns of illustrations prepared by that person. Recently, many design tools for promoting free design have been developed. However, preferences for various colors differ depending on individual personality. Therefore, a system that can automatically color various designs on the basis of human preference is required. In this study, we propose an automatic modeling system that can be used to model illustrations. To verify the effectiveness of the proposed system, we simulate a coloring design experiment to determine the color patterns preferred by some subjects by using various design data. By using the design data, we determine each subjects preferred color pattern, and send feedback on these individual color patterns to the proposed system.
A line-start permanent-magnet synchronous motor (LSPMM) consists of a stator with symmetrical three-phase armature windings and a salient pole rotor with a permanent magnet for excitation and a starting winding similar to the squirrel-cage winding of an induction motor. In this paper, a general analytical method based on tensor analysis is proposed for practical performance calculation of a three-phase LSPMM. The general equation for the currents of the three-phase LSPMM is derived from the transient impedance tensor expressed in polyphase symmetrical axes, and the general equation for vibratory and non-vibratory torques is derived from the current equation.
This paper presents novel bridgeless power factor correction circuits that achieve both high reliability and high efficiency. The proposed circuits can protect silicon carbide Schottky barrier diodes, MOSFETs, and body diodes against flowing high inrush current without impairing efficiency. This paper introduces the principle of operation including the control scheme and the simulation and experimental results.
In recent years, contactless transfer of electric power has received worldwide attention. Among many contactless electric power transmission systems, an electromagnetic resonant system showed a remarkable ability to turn on a 60 watt light bulb that was at a distances of 2 meters from a power source. Several papers that explain the principle of the system have been published, but an analytical explanation of this principle has not been provided. In this paper, the author provides an analytical explanation of the principle behind the power transfer system. The analysis can facilitate the evaluation of the characteristics of the system, such as resonant frequencies, transferable power, efficiency, coil voltages, etc., and may be useful in the synthesis of contactless power transfer systems.
Two-wheeled systems have many advantages compared to statically stable systems. This paper describes a control strategy of dynamically-balanced two-wheeled wheelchair system that does not have any front casters. In this system, rider can sit the seat and control the motion of the system by adjusting CoG of his/her body. Unlike other commercial two-wheeled systems, CoG position of the upper body is mainly determined by the position of the user. Thus, there is a possibility that CoG position may not overlap with the wheel axis. In that case, sensor information cannot be used to measure the exact position of the CoG. This paper shows an estimation of method of the unknown CoG position for Two-Wheeled Dynamically-Balanced Wheelchair (TWDBW) is considered. Gravity torque observer with a compliance control is utilized to realize stable compensation according to the variable CoG position. Backstepping based nonlinear control design is applied to regulate and track the CoG motion of the upper body in the TWDBW. The validity of proposed method is verified by simulation and experimental results.
Anti-slip control or slip ratio control can help improve the stability of EVs on a low-µ road. However, these control methods cannot control the driving torque. In this paper, we propose a driving torque control method for EVs with in-wheel motors. By using this method, we can control the driving torque directly. Simulations and experiments are carried out to demonstrate the effectiveness of the proposed method.
When electric double-layer capacitors (EDLCs) are connected in series, cell voltage imbalance that results due to non-uniform cell properties is observed. Cell voltage imbalance should be minimized to prolong cycle lives and maximize the available energy of cells. In this study, we propose a series-parallel reconfigurable cell voltage equalizer that is considered suitable for energy-storage systems using EDLCs instead of traditional secondary batteries as main energy-storage sources. The proposed equalizer requires only EDLCs and switches as its main circuit elements, and it utilizes EDLCs not only for energy storage but also for equalization. An equivalent circuit model using equivalent resistors that can be regarded as an index of equalization speed is developed. Current distribution and cell voltage imbalance during operation are quantitatively generalized. Experimental charge-discharge tests were performed for EDLC modules to demonstrate the performance of the cell voltage equalizer. All the cells in the modules could be charged/discharged uniformly even when a degradation-mimicking cell was intentionally included in the module. The resultant cell voltage imbalances and current distributions were in good agreement with those predicted by mathematical analyses.
Conventional cell/module voltage equalizers or equalization chargers based on traditional dc-dc converters require numerous switches or transformers as the number of series connections increases; therefore, their cost and complexity tend to increase and their reliability decreases as the number of connections increases. This paper proposes a novel voltage equalization charger that consists only of passive components such as capacitors, diodes, and a transformer. The fundamental operating principle, major features, and derivation of equivalent dc circuits are presented. A symmetrical configuration is also proposed to mitigate the RMS current flowing through energy storage cells in the charging process. Simulations and experimental charging and cycle tests were performed on series-connected electric double-layer capacitor modules to demonstrate the equalization performance. The experimental and simulation results were in good agreement, and the voltage imbalances were gradually eliminated as time elapsed even during charge-discharge cycling.
The measurement of circuit parasitic parameters and evaluation of equivalent circuit models are necessary for a noise analysis or a high-speed operation circuit design of power electronics circuits. Recently, time domain reflectmetry (TDR) has emerged as a technique for measuring circuit parameters. This paper proposes a TDR method for measuring the voltage-dependent capacitance of a power MOSFET. This method can be used to measure the output capacitance Coss of a MOSFET for any DC bias voltage. The Coss of a MOSFET with VDS=350 V was measured in an experiment, while the datasheet gives values of Coss only for V DS values in the range 35-100 V.
Recently, multi-dimensional actuators have been attracting considerable interest because of the solution for increase in size and weight. In this paper, we propose a position feedback control method using optical image sensors for an actuator with three degrees of freedom. The validity of this control method is verified on the basis of the measurement results.
Power conversion electronics for photovoltaic (PV) systems are desired to operate as efficiently as possible to exploit the power generated by PV modules. This paper proposes a novel PV system in which a dc-dc converter is partially connected to series-connected PV modules. The proposed system achieves high power-conversion efficiency by reducing the passing power and input/output voltages of the converter. The theoretical operating principle was experimentally validated. Resultant efficiency performances of the proposed and conventional systems demonstrated that the proposed system was more efficient in terms of power conversion though the identical converter was used for the both systems.
A novel three-phase triple-voltage rectifier circuit is presented. The proposed circuit applies the single-phase diode charge pump scheme to the three-phase system and the direct output voltage is about 3 times much than input line-to-line voltage. The validity for the proposed circuit is demonstrated by the simulations and the experiments.
This paper proposes an image based measurement system of physical motion of vehicle driver for motion analysis and evaluation of the driving feelings. The optical marker for the measurement consists of high intensity LEDs and it can optically specify the marker number. This copes with problems in marker based measurement systems, such as occlusions and swappings. Experimental results show that steering delay of the driver lowers when it sets front suspension of the vehicle to high dumping.
In this paper, the fuel consumption of the hybrid electric vehicles is analyzed by the rated power of the engine and the motor. The analysis was based on the published data only. Hybrid ratio and normalized fuel consumption are defined. As the result, the key for the high mileage of hybrid electric vehicle is to use the high power motor and the low power engine.