Manabu Ishitobi

Inductor snubber-assisted series resonant ZCS-PFM high frequency inverter link DC-DC converter with voltage multiplier

A variety of high voltage DC power supplies employing the high frequency inverter have difficulty in achieving soft switching considering a quick response and no overshoot response under the wide load conditions which are used in a medical-use X-ray high voltage generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1.25 A, respectively. The authors develop a soft switching high voltage DC power supply designed for X-ray power generator applications, which uses lossless inductor snubber-assisted series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the secondary side of a high frequency high voltage transformer with a large turns ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary side of turn numbers and stray capacitance of high voltage high frequency transformer is greatly reduced. It is proved that the proposed zero current switching (ZCS) DC-DC high voltage converter topology with dual mode frequency modulation mode control scheme can obtain good transient response and steady-state performance in high voltage X-ray tube load. The effectiveness of this high voltage converter with a high frequency link is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

Current-source type parallel inductor-compensated load resonant inverter with PDM control scheme for efficient ozonizer

This paper is concerned with a study on the high-frequency current source-fed type parallel inductor-compensated load-resonant inverter for an ozonizer, together with some output regulation characteristics. In addition, an effective power control method for a current-source inverter type ozonizer is introduced. This inverter can operate under the principle of the PDM (pulse density modulation) and PWM hybrid power regulation strategy. It is noted that this inverter makes the control system simple, thus leading to improve the ozone generation efficiency.

Pulse width and pulse frequency modulation pattern controlled ZVS inverter type AC-DC power converter with lowered utility AC grid side harmonic current components for magnetron drive

The grid voltage of commercial utility power source in Japan and USA is 100 V, but in China and European countries, it is 200 V. In recent years, in Japan, 200 V output single-phase three-wire power systems have begun to be used for high power applications. In 100 V utility AC power applications and systems, an active voltage clamped quasi-resonant inverter circuit topology using IGBTs has been effectively used so far for the consumer microwave oven. In this paper, the authors present a half bridge type voltage-clamped high-frequency inverter type AC-DC power converter using which is designed for consumer magnetron drives used in consumer microwave ovens on 200 V utility AC power systems. This zero voltage soft switching inverter can use the same power rated switching semiconductor devices and three-winding high frequency transformer as those of the active voltage clamped quasi-resonant inverter using the IGBTs that has already been used for 100 V utility AC power sources. The operating performances of the voltage source single ended push pull type inverter are evaluated and discussed for a consumer microwave oven. The harmonic line current components in the utility AC power side of the AC-DC power converter operating at ZVS-PWM strategy were reduced and improved upon the basis of sine wave like pulse frequency modulation and sine wave like pulse width modulation for the utility AC voltage source.

Transformer parasitic parameters and lossless inductive snubber assisted zero current soft switching DC-DC converter for high power magnetron drive

This paper presents a novel prototype of a high-frequency transformer parasitic parameter and a lossless inductive snubber assisted series-resonant ZCS-PFM DC-DC power converter, which is designed for high power magnetron. When a conventional series-resonant PFM DC-DC converter is designed for magnetron drive, it is very difficult to implement zero current soft switching commutation due to the influence of the magnetizing current through a high-frequency transformer. In order to implement soft switching commutation, the new topology that can actively utilize the magnetizing current is proposed and discussed on the basis of simulation and experimental results.

Transformer parasitic parameter and lossless inductive snubber assisted zero current soft switching power supply for power microwave generator

This paper present a novel prototype of a high-frequency transformer parasitic parameter and a lossless inductive snubber assisted series-resonant ZCS-PFM DC-DC power converter, which is designed for high power magnetron. When a conventional series-resonant PFM DC-DC converter is designed for magnetron drive, it is very difficult to implement zero current soft switching commutation due to the influence of the magnetizing current through a high-frequency transformer. In order to implement soft switching commutation, the new topology that can actively utilize the magnetizing current is proposed and evaluated the performance in the prototype of power microwave generator.

Pulse pattern modulated soft commutation inverter-type AC-DC power converter with harmonic current components reduction in utility power side

In this paper, a circuit topology of a half bridge quasi-resonant ZVS-PWM high frequency inverter type AC-DC converter using IGBTs for the consumer magnetron drive is presented, which can use the high frequency high voltage transformer, voltage doubler and power semiconductor switching devices (IGBTs) used in active voltage clamped quasi-resonant PWM inverters suitable for 100 V utility AC power systems. The operating analysis and characteristic evaluations of a switching power supply converter circuit for a microwave oven in a 200 VAC utility power system used in Europe, China and Japan are discussed on the basis of simulation and experimental results. Moreover, a new 60 Hz sinewave partial pulse modulation pattern control scheme of the pulse operating frequency modulation and pulse width modulation is proposed and discussed in order to improve harmonic current components in 200 V utility AC power grid under a condition of the peak limitation of the magnetron anode current.