Masataro Nishimura

Overlapping commutation-mode analysis of a high-frequency inverter

This paper describes the steady-state operating analysis and performance evaluation of a high-frequency inverter for high-intensity ultrasonic power supply. The high-frequency inverter using reverse-conducting thyristors (abbreviated RTh type inverter) is analysed with an R–C load model of the ultrasonic transducer System. The steady-state characteristics and circuit operation, in which the overlapping commutcation-mode is considered, are quantitatively discussed and compared with those of a basic series-capacitor-commutated inverter (abbreviated basic type inverter). The necessary data for circuit design of the power supply are also presented.

Overlapping commutation mode analysis and stable operating regions of a basic series-inverter circuit

The overlapping commutation mode analysis of a basic series-inverter circuit is analytically explained in relation to the normalized loading parameter λ and normalized control variable μ. The operation of this circuit in overlapping modes is introduced and the circuit stable operating regions are exactly defined, also some interesting characteristics which contradict the traditional analogies are pointed out. For simplifying the calculations the circuit is analysed with a resistive load at the steady state and the mutual coupling between two inductors of this circuit is not considered in this paper.

Load Characteristics of Ultrasonic Power Supply for Fuel Improvement

Typical load characteristics of a high-power ultrasonic homogenizer equipment for used with fuel improvement are described.The load equivalent circuit as an electrical-acoustic conversion system is derived from practical consideration of power supply designing. On the basis of that equivalent circuit, the load variations such as depth, clearance, viscosity, and output frequency changes are analyzed as load admittance changes. The load characteristic is experimented by a constant current system.Especially, in the case of mechanical resonance frequency tracking strategy, a result that the load admittance variation with load change is extremely small is proved.Further, a tracking strategy method of mechanical resonance frequency is investigated.

Stable Operation of High-Power Ultrasonic Power Supply for Fuel Improvement

The high-intensity ultrasonic homogenizer equipment, which is composed of high-power ultrasonic transducer and mechanical resonant couplers, is to be noted for the fuel improvement system.As a power supply for that system, the high-frequency thyristor inverters are more hopeful than power transistor oscillators.This paper describes the transient-state operating analysis and performance evaluations of a high-frequency inverter for high-intensity ultrasonic power supply. The high-frequency inverter using reverse-conducting thyristors (abbreviated RTh type inverter) is analysed with an R-C load model of the ultrasonic transducer systems.The transient-state characteristics and circuit operation, in which the overlapping commutationmode is considered, are quantitatively discussed comparing with those of basic series-capacitor-commutated inverter (abbreviated basic type inverter), and the necessary data for circuit design of the power supply are supplemented here.

Laser Radar, Data Processing System and Measurements of Air Pollutions

Summary Laser raday systems for documenting spatial and temporal variation of relative density of aerosols using Mie backscattering, and that for detecting NO 2 in atmosphere using the resonance fluorescence of NO 2 are presented. For observation of aerosols, a very flexible data processing system using both a mini-computer and microprocessor has been assembled to meet the needs of various controls and computations including data acquisition, data transfer and storage, computations of the radar equation and display on CRT. The combination of the second harmonic of a Nd: YAG laser, a synchronous single photo-electron technique and a narrow pass band optical filter employed for separation of scattered light by NO 2 resonance fluorescence offers a sensitive system for remote monitoring of NO 2 in atmosphere. Experimental results by these system are also presented.