J. Yoshitsugu

Switched-mode PFC rectifier with high-frequency transformer link for high-power density single phase UPS

The general purpose of single-phase UPS topologies are indispensable for the considerable reduction of harmonic current components in AC mains as well as realization of unity power factor correction (PFC). In particular, the single phase PFC rectifier with a high-frequency isolation transformer link has some advantages as an electrically-isolated AC/DC conversion circuit for small scale UPS. This UPS is capable of eliminating harmonic currents, leak current components and realizing an isolation between AC input and DC output power stage as well as matching the DC voltage of the PWM inverter by means of incorporating a compact high frequency transformer into high-frequency intermediate state. Three types of isolated PFC rectifiers designed for 2 kVA, 3 kVA and 5 kVA-UPSs are put into practical use respectively, as new topology. This paper presents a high-frequency link PFC rectifier, its related operating principle and control strategy, together with the steady-state and dynamic state performances of these types of UPSs developed from a practical point of view.

Zero voltage soft-commutation PWM DC-DC converter with saturable reactor switch-cascaded diode rectifier

An improved single-ended push-pull (SEPP) half-bridge type zero-voltage soft-switching pulse width modulation (ZVS-PWM) DC-DC power converter is presented in this paper, which makes use of a saturable reactor-assisted lossless capacitor type zero voltage soft-switching method. The SEPP power converter with a high-frequency forward and flyback hybrid transformer link has some advantages such as lowered switching and conduction losses, soft-switching transition operation over a wide load range, constant frequency PWM regulation and minimized Electro Magnetic Interference (EMI) as well as Radio Frequency Interference (RFI) noises. Its operating principle is illustrated and its periodic steady-state circuit analysis is implemented. In order to demonstrate the remarkable effectiveness of this converters characteristics, feasibility experiments are conducted with a 150 W/200 kHz prototype of a high-frequency link ZVS-PWM DC-DC converter using power MOSFETs with an ultrafast soft-recovery diode.

Fuzzy auto-tuning scheme based on /spl alpha/-parameter ultimate sensitivity method for AC speed servo system

The authors introduce a load speed feedback control to prevent the mechanically-resonant vibration in AC servo motor drive motion system with two-mass mechanical motion load. In order to compensate three characteristic system gain parameters, the /spl alpha/-parameter ultimate sensitivity method based on partial model matching method is proposed. Moreover, a fuzzy reasoning algorithm is applied to compensate this parameter /spl alpha/. The effectiveness of this advanced auto-tuning control scheme in the AC speed servo system is verified by computer simulation.

Resonant DC link snubber-assisted soft switching inverter type AC servo driver with low common mode current characteristics

This paper presents an auxiliary active quasi-resonant DC link snubber-assisted three phase voltage source type soft-switching inverter used for the AC servomotor drive applications. At first, the operation of this quasi-resonant DC link snubber circuit and its circuit parameter design method are described. In the second place, three phase voltage source soft switching inverter using a quasi-resonant DC link snubber topology treated here is discussed and evaluated from an experimental point of view. Finally, its common mode current on the inverter driven motor side is evaluated for soft-switching inverter-fed permanent magnet AC motor drive system and compared with that of the conventional hard switching inverter system.

A feasible high-performance single-phase UPS incorporating switched mode rectifier with high-frequency transformer link

It is essential for an uninterruptible power supply (UPS) to eliminate harmonic currents in its input current and to get unity power factor. The switched mode rectifier (SMR) with a high-frequency transformer link has promising characteristics as an AC/DC conversion circuit for UPS. It does not only eliminate harmonic currents but also provides an isolation between AC input and DC output with a small high frequency transformer. We applied the SMR for the development of UPS with capacity of 2 kVA, 3 kVA and 5 kVA. This paper presents circuit configurations and control strategies of the SMR and the test results of the developed UPS.

Active edge-resonant DC link snubber-assisted three phase soft switching inverter for AC servo drive

This paper presents an auxiliary active quasi-resonant DC link snubber-assisted three phase voltage source type soft-switching inverter for AC servo motor drive applications. The operation of this quasi-resonant DC link snubber circuit and its circuit parameter design method are described and three phase voltage source soft switching inverter using a quasi-resonant DC link snubber treated here is evaluated and discussed from an experimental point of view. In addition to these, the motor current and the motor speed response under the soft switching are compared with that of the conventional hard switching condition. The effectiveness of the soft switching inverter-fed permanent magnet AC servo motor drive system is proven by the common mode current in the inverter driven motor side and the conductive noise in the mains terminal interface voltage as compared with those of the conventional hard switching inverter-fed permanent AC servo motor drive system.

Improved control strategy on single-phase PWM current source inverter with pulse area modulation

In recent years, single-phase PWM current source bridge inverters using active power switches in series with a diode have attracted special interest in place of voltage-fed PWM inverters in utility-interactive power systems. On the other hand, this type of inverter has a significant disadvantage to be improved in practical applications, in that the output current delivered from this inverter includes a large amount of harmonic components when the smoothing DC reactor is not large enough to sufficiently eliminate the ripple components in the DC current. Thus, this paper presents an effective pulse area modulation control strategy to eliminate the harmonic current components in the AC side of single-phase current source PWM inverters. The principle of the proposed control strategy for this inverter system is described, and its simulation results are introduced and evaluated.

Fuzzy logic based auto-tuning using /spl alpha/-parameter ultimate sensitivity method for AC servo motion drive

In this paper, an auto-tuning control scheme which is based on fuzzy reasoning logic with a load speed feedback scheme using the /spl alpha/-parameter ultimate sensitivity method is proposed and discussed for DC brushless motor-based AC servo drives in two-mass mechanical motion systems from a theoretical point of view.

Proposal of practical load speed observer for AC servo system with two-mass mechanically-resonant load and its experimental evaluation

In this paper, two types of load speed observers especially designed for load speed feedback compensation AC servo system with mechanically resonant load are proposed. The effectiveness of the observers are verified on the basis of both computer simulation and experiment.

A Novel Three-phase Active Ac/dc Converter Operating At Discontinuous Current Mode

Discontinuous current mode control scheme for single phase AC-DC converter with active power fdtering function and power factor correction has got widespread usages in telecommunication energy plants. This control scheme has a practical advantage of a simple codguration and is cost-effectiveness. However, it has not been effectively adopted for three phase input power supplies because the characteristics of conventional control scheme have some disadvantages for three phase AC mains. Thus, a new and simple circuit configuration with discontinuous current mode control scheme suitable for three phase AC mains is proposed newly. This paper presents an operating principle and unique features of the proposed three phase active AC/DC converter circuit topology, along with harmonic current evaluations on the basis of simula tion results of this con verter.