Masakatsu Nomura

Direct Space Vector PWM Strategies for Three-Phase to Three-Phase Matrix Converter

This paper proposes 3 types of new direct space vector modulation methods for three-phase to three-phase matrix converters. The space vector modulation method allows a direct understanding of switching patterns and their characteristics from the viewpoint of analysis and control. Output voltage harmonics and switching losses can be reduced across the entire voltage region by making use of the direct AC/AC conversion approach. The switching count can be reduced even further by fully utilizing the output current detection value. The conventional virtual indirect conversion approach is first described and then the selection method of space vectors is explained along with the duty calculation technique in direct space vector modulation. Finally, the validity of the proposed method is proven from simulation and analysis results.

Periodic learning suppression control of torque ripple utilizing system identification for permanent magnet synchronous motors

This paper introduces two torque ripple suppression control methods for permanent magnet synchronous motor. With a system identification technique, the system model from compensating current input to torque detection output can be expressed as the speed-adjustable 1-dimension complex vector in the coordinate system synchronizing with the torque ripple frequency. The first method introduces a periodic learning I-P control system of compensating current to create the feed-forward compensation tables. The second introduces a speed-adjustable periodic disturbance observer which can improve the transient suppression characteristics. Both methods are suitable for the adjustable-speed drive, so the control parameters and reference model can be adjusted automatically. The most important thing is with these methods excellent performance for mechanical resonance suppression caused by torque ripples can be gotten. And this paper shows the analysis and experimental results to support the methods.

A high response induction motor control system with compensation for secondary resistance variation

A high response digital speed control system for the induction motor drive, which is based on the decoupled control method, has been developed. This control system can compensate the error of the time constant caused by the variation of temperature in the secondary circuit of the induction motor. This paper presents the principle of the control system and experimental results and discusses the compensation for the error of the secondary time constant.

Control of Standard Engine Test Bench System for Dynamic Road Load Tests

We developed a new engine test bench system available for dynamic road load tests. The mechanical system of the engine test bench system is as same as a standard engine test bench system. To control it, we adoped I-PD-like 3rd order controller, a virtual vehicle model and engine angular velocity estimator. Our engine test bench system enables to do various tests of an engine without a driveline or a vehicle body, but the engine is loaded as if it were mounted in a vehicle

Prototype and characteristics measurement of bearingless motor with wide air gap structure

Nowadays, more and more applications have been developed along with continuous research on magnetic suspension. In these applications, wide air gap structure always plays an important role. Therefore, bearingless motor with such structure which can provide large magnetic suspension force was proposed. This paper shows the experimental results of such bearingless motor based on a prototype model and high efficiency and stabilized transitional characteristic were specified.

Decoupling torque control system for automotive engine tester

This paper presents a novel decoupling control method for the engine torque control of an automobile engine tester. The engine tester is mainly composed of a dynamometer control system and an engine control system. The conventional engine tester has the problem that the performance of the engine torque control system is deteriorated by the influences of the interference between the dynamometer speed control system and the engine torque control system. The authors proposed the practical engine torque control system based on an observer and an identification system to eliminate the interference of the dynamometer speed control system. The effect of observers parameter error on the engine torque estimation response was analyzed. According to the result of this analysis, a practical method is proposed to identify the engine inertia moment and the shaft spring coefficient that are parameters of the observer. The authors confirmed through simulation and experiments that the proposed decoupling engine torque control system realizes a robust control system from the interference with the dynamometer speed control system.

A new boost type cascaded inverter with single DC source

Cascaded multilevel inverters with Y-connection or Delta-connection have been proposed for high voltage applications. However, these topologies always require isolated transformers for each inverter cell, which makes cost high and wiring complex. Furthermore, system weight and volume also increase accordingly. This paper presents two new types of boost type delta-connection cascaded inverters with only a single DC source. Based on it, a suitable voltage control with PWM modulation is also proposed to improve the inverter control performance and DC capacitors voltage fluctuation. Verification has been carried out by simulation with MATLAB.

Load following characteristics and operating temperature control of SOFC simulation

Among different types of fuel cells, solid oxide fuel cells (SOFCs) show great potential applications due to many advantages such as low emission, high efficiency, and high power rating. On the other hand, SOFC systems are beneficial because they can convert fuel such as natural gas which is supplied by popular systems in many countries into electricity efficiently using internal reforming. In facts, the load demand changes flexibly and fuel cell life time decreases by rapid thermal change. Therefore, it is important to acquire the load following performance as well as control of operation temperature. This paper addresses components of the simple SOFC power unit model used for following the variation of load demand at a local location that considers temperature characteristics using the Simulink.

An integrated function of photovoltaic generator supplying to nonlinear load: Active power filter

The PV generation is increasingly popular nowadays while typical loads require more high power quality. Basically, one PV generator supplying to nonlinear load is desired to be integrated with a function as an active power filter (APF). In this paper, the proposed three-phase three-wire system including PV generation, DC/DC boost converter to extract maximum radiation power by using MPPT and DC/AC converter to acts as an APF will be presented. The instantaneous power theory is applied to design the PV-APF controller which shows reliable performances. The Matlab/SimpowerSytem tool has proved that combined system can simultaneously inject maximum power from PV unit and compensate harmonic current drawn by nonlinear loads.

Reliable Impedance Islanding Detection for Power Distribution Systems with High Motor Penetration

Regarding to dispersed generation field, an islanding is known as a situation that those generators are disconnected from the utility feeders and a bunch of local loads being powered by them is isolated. Accordingly, anti-islanding schemes are used to immediately detect that phenomenon in facilitating the detachment the DG or adaptive controlling of autonomous operation. Negative-sequence impedance measurement is considered as a novel method of detecting electrical islands in DG networks. However, in the case of high induction motor penetration, this method might malfunction. Using two-round impedance measurement, this paper deals with that problem while making typical assessments on how the impedance tolerant values are selected and how these values vary with network configuration. The simulation in PSCAD/EMTDC and experiments validate the methodology.