Hiroyasu Kifune

A novel ZCS high frequency inverter with complex resonance and design procedure for high amplitude of output current

A novel ZCS (zero current switching) high frequency inverter with complex resonance applied for the induction heating (IH) of a steam superheater is developed. The complex resonant technique is adopted for the high frequency power supply to realize the high amplitude of output current. The switching stress of the main active switch as peak current and peak voltage is suppressed. The ZCS operation of all the switches can be performed using overlapping commutation phenomenon. The ZCS characteristics are investigated and the ZCS high frequency inverter is effectively applied for the IH load.

Novel constant frequency time ratio controlled series load resonant high frequency soft switching inverter

Series load resonant high frequency soft switching inverter with constant frequency power regulation function is presented. Proposed inverter supplies high frequency power to load by push pull operation which is provided by series load resonance and two ZCS switching cells as main switches. Main switching cell consists of reverse blocked active power switch and unidirectional lossless inductor snubber. Power regulation under constant output frequency is achieved by the PWM-ZVS auxiliary switch. The principle of ZCS operation using overlapping commutation and power regulation scheme are described. Test circuit is designed for actual induction heating application based on the numerical analysis. The characteristics of the power regulation with PWM provided by auxiliary switch in constant frequency are evaluated and verified experimentally. The soft switching operation for all switching devices is ensured through the high frequency induction heating application.

Novel load adaptive frequency tracking control scheme for high frequency inverter without PLL scheme

A Load adaptive frequency tracking control scheme that is named conduction time balanced loop (CTBL) for the high frequency inverter is presented without PLL scheme. Using this control method for the gate circuit of the high frequency inverter that operates in resonant frequency, it is realized to have both the power regulation function and the load adaptive tracking control function by one inverter, though the conventional PLL high frequency inverter cannot do. This paper describes the principle of the proposed control scheme with high frequency inverter operation and the relation between the CTBL and the power regulation by the phase shift modulation.

A method of power regulation applied to the high frequency inverter for the IH home appliances

This paper describes a power regulation concept; CFPDM (Commercial Frequency Pulse Density Modulation) of the high frequency inverter for induction heating home appliances. CFPDM is a new type of PDM and it is easy to put CFPDM into practical use for any circuit topologies without any additional switches and passive components. Conventional PDM (Pulse Density Modulation) enables the high frequency inverter to control the output power over a broad range and to realize high power conversion efficiency at the same time. However, the resonant frequency of non-smoothing filter is close to the duty frequency of PDM, which may cause other harmonic current problems. In CFPDM, the duty frequency is set to lower than the line frequency unlike PLL. Therefore CFPDM surpass the advantages of PDM and also avoids generating harmonic current. This paper shows the sample of CFPDM controller and the operation principle by using simulated results. A prototype soft switching SEPP high frequency inverter controlled by CFPDM has been tested. Some experimental results of it are shown finally.

Cost effective soft-switching PWM high frequency inverter with minimum circuit components for consumer induction heater

This paper presents a novel prototype soft-switching PWM high frequency inverter with minimum circuit components, which can achieve the wider and more stable soft commutation, simpler circuit configuration, smaller size, lower cost and higher-efficiency as compared with active voltage clamped ZVS-PWM and single-ended ZVS-PFM high frequency inverters developed previously. This quasiresonant soft-switching PWM high frequency inverter operating under ZVS and ZCS arms-related soft commutation is including the voltage-clamped ZVS-PWM inverter in the constant frequency variable power scheme as well as a single-ended ZVS-PFM inverter. The operation principle of soft switching PWM high frequency inverter treated here is described on the basis of the simulation and experimental results, together with its comparative operating performances in steady state. The practical effectiveness of a novel type high frequency soft-switching PWM inverter using state-of-the-art IGBT power modules is actuary proved for consumer induction heated appliances as cooker, super heated steamer and hot water producer.

ZCS high frequency inverter for induction heating with quasi-constant frequency power control

This paper describes a novel zero current switching (ZCS) high frequency inverter with quasi-constant frequency power control (Q-CFPC) developed for induction heating of a marine application. The principle of the ZCS operation of Q-CFPC are illustrated and graphically compared with conventional ZCS high frequency inverters. The characteristics of ZCS operation in Q-CFPC are analyzed on the basis of simulation and verified experimentally.

A method of circuit design based on the experimental analysis of high-intensity ultrasonic transducer and the numerical analysis of zero current soft switching inverter using current overlapping commutation

This paper describes the electrical characteristics of an ultrasonic transducer through the results of experiments from the point of view of driving by inverter. In order to realize ZCS operation of the inverter, the characteristics of inverter are calculated using normalized numerical analysis. Optimized circuit design based on the experimental and numerical analyses is presented with consideration of switching stresses.

The design based on the numerical analysis of the SEPP-ZCS inverter for high-intensity ultrasonic homogenizer

The inverter circuit for high-intensity ultrasonic generator is demanded to work over a wide range of load, because the ultrasonic transducer has extremely high mechanical quality factor and slight difference of load condition to it greatly influences its operation. This paper proposes a method of circuit design based on the numerical analysis to achieve zero current soft switching operation in any load condition of the inverter, to suppress switching stresses, and to reduce distortion factor of inverter output voltage.

Fuel Saving Effect of Hybrid Propulsion System - Case: Tugboat is not in Service

Harbor tugboat has two middle-high speed and high power engines than general cargo vessel of similar size so that it pushes and pulls large vessels. Fig.1 shows a sample of real data which was measured a trend of a demanded output power while the tugboat is operated in one working cycle for about three hours. This data is classified to analyze the tugboat’s operation into two situations. In service situation, the tugboat works to push or pull the large vessel under pilot order. Not in service situation shows the left of the working time including transit time between tug’s base and the working spot and waiting time for starting service. Fig.2 illustrates the demanded propulsion power and its frequency in use. As is clear from Fig.2, a wide range of propulsion power is required in service situation. On the other hand, in transit and waiting situation, a demanded propulsion power is not high but low power less than 20%. In other words, the duration time that tugboat’s main engines are operated at low loaded condition is long in both situations. Generally, the thermal efficiency of engine for ship is low in low loaded condition. Tugboat’s engine tends to be operated in low load and low efficiency for a long time. For this reason, it is effective to improve the thermal efficiency in low loaded condition. By focusing on this characteristic, several challenging projects have implemented to save fuel by employing hybrid propulsion system (1) (3). It is reported that an efficiency of propulsion system is improved by using large capacity rechargeable battery as one of power source and an energy buffer when the demanded power is low. However, an initial cost for ship building goes up in price since it is necessary to add several apparatuses which include battery, motor generators, electric power converters, and their controller for realizing the system. Thus, many of Fuel Saving Effect of Hybrid Propulsion System

Development of Diesel Particulate Filter Constructed from Nonwoven Fabric Metallic Fiber Filter Applying Induction Heating

近年,ディーゼルエンジンから排出される粒子状 物質(PM)は,喘息や肺がん,アレルギーの原因と して対策が重要視されおり,カリフォルニア沿岸 など,一部地域では具体的数値による PM 排出規制 が行われている.また、国際海事機構(IMO)では MALPOL 条約の付属議定書VIにおいて,燃料中の硫 黄分濃度の低減という形で規制されている.しか し,船舶のディーゼルエンジンの燃料油は,ディー ゼル車の軽油と違って,硫黄分の多い重油であり, ディーゼル車用 DPF 技術は適用できず,新しい DPF 技術の開発が必要となる.そこで,様々な PM低減技 術が開発されているが,それらの多くは,PM の二次 処理が必要など,メンテナンス上の問題がある. 本研究では,不織布金属フィルタに捕集された PM は,約 650°C以上まで誘導加熱によって加熱さ れ,短時間で燃焼処理することにより,DPF の再生 を行い,メンテナンス性の良い同一装置内での PM の捕集と DPF再生システムを実現している.本研究 では,PM 捕集実験による DPF の性能評価,およ び,DPF 再生実験による評価・検討,並びに連続運転 による繰り返し実験を実施したので報告する.