Yushin Yamamoto

Three phase parallel processing UPS using multi-functional inverter

A parallel processing uninterruptible power supply (UPS) system is proposed in which a three-phase pulse-width modulation (PWM) inverter is connected in parallel to a utility power source through an inductance and an electronic switch. In this system, when the utility power is on, the inverter controls the voltage regulation of the inductance so as to control the output voltage constantly in synchronization with the utility. The batteries are charged by the inverter at the same time. The inverter also absorbs the load harmonics so as to obtain a sinusoidal output voltage. When a power failure happens, the electronic switch in the input line is turned off and the inverter operates alone with no break of power supply to the load. Using only one inverter, the parallel processing UPS realizes a combined system of a constant voltage power source, an uninterruptible power supply, and a harmonics absorbing active filter. This system can also link new types of DC power sources, such as fuel cells or photovoltaic cells, to utility power systems.<<ETX>>

Dead beat control of three phase PWM inverter

This paper proposes new method of high performance current and/or voltage control of three phase PWM inverter, especially suitable for high speed switching devices such as Transistor and BIMOS. As the controller for calculation of the dead beat algorism, a high speed digital controller, such as the digital signal processor is assumed. Following new methods are successfully adopted and combined to realize high quality. (1) Three phase inverter current and voltage are transformed to synchronizing d-q-0 frame, and discretized equations of current and voltage are derived, which clearly reveal coupling of voltage and current of inverter on d-q frame. (2) Using above discretized equation of main circuit, algorism of Dead Beat control with compensation for decoupling is developed. (3) New method for compensation of computing time delay and full utilization of sampling interval for inverter output pulse width is developed, which utilizes 2nd order load current prediction and discretization with twice time of sampling period. (4) Double Dead Beat control system is developed for sinusoidal output voltage inverter, which has high speed current minor loop to constrain inverter current within safety limit. Validity of these techniques has been confirmed by simulation using a hybrid computer.

UPS Systems using Multi-functional Inverters

This paper proposes a high performance multi-functional inverter and its several applications for UPS systems. High frequency PWM voltage source inverter using high speed switching devices such as BIMOS are adopted as the multi-functional inverter. The inverter has current minor control loop and functions as a sinusoidal wave voltage source, an active harmonic suppressor and a high power factor charger with sinusoidal wave input current. Dead beat control (finite-time settling control) is successfully adopted as the current and voltage control of this inverter. The inverter has quick response characteristics and can operate at plural output frequencies such as 50, 60 and 400 Hz. The combination of the multi-functional inverters and high speed electronic switches realizes several new types of redundant UPS system with minimum number of converters.

A novel active common-noise canceler combining feedforward and feedback control

This paper proposes a novel type of an active common noise canceler (ACC) combining feedforward and feedback control. The ACC attenuates the common-mode (CM) voltage and suppresses EMI emissions by adding the CM voltage of reverse polarity to the CM voltage generated by inverters in AC motor drive system. The proposed ACC uses feedforward and feedback control whereas the original ACC [19] uses feedforward control only. Experimental evaluation is presented for comparison between the proposed ACC, a feedforward ACC, and common-mode chokes (CMCs) which are widely used as passive filters. The experimental results show that the proposed ACC has large CM voltage attenuation of up to 50 dB in the wide frequency range. The attenuation performance of the proposed ACC is larger than the feedforward ACC and a CMC, which uses the same ferrite core and windings used in the proposed ACC.