Toru Maruhashi

Computation of sensitivities with respect to conduction time of power semiconductors and quick determination of steady state for closed-loop power electronic systems

Two problems related to computer-aided analysis of power electronic systems are dealt with. Firstly, an efficient algorithm is proposed for computing sensitivities of system behavior with respect to conduction time of power semiconductors for general power electronic systems. The adjoint network approach based on Tellegens theorem is extended for computing those sensitivities in an accurate and efficient manner. Secondly, a method for quick determination of the steady state of power electronic systems with closed control loops is discussed. An efficient algorithm for computing the steady state is proposed that makes use of the computed sensitivities.<<ETX>>

Resonant vector control base high frequency inverter

The authors introduce a new configuration of resonant type high-frequency inverter which has inherent fast-response Variable Voltage Variable Frequency (WVF) strategy and high power adaptability.

A phase-difference angle control-mode PWM high-frequency resonant inverters using static induction-transistors and-thyristors

Power Conditioning and Processing of voltage-fed series resonant inverters and converters using Static Induction Devices are actually performed in terms of operating frequency control or fixed frequency variable voltage control schemes by the authors. These control methods have disadvantages of either restricted power control range or unreliable switching operation. The authors propose a new combined control-based on the basis of a phase-shifting angle control-mode PWM strategy between left and right switching arms of the series resonant full-bridge inverter with an adaptive frequency servo regulation function for maintaining switching-device operating-mode in a reliable-and an efficient condition. Practical implementation of this control circuit is described that utilizes two channel phase-locked loop systems together with a frequency tracking system by a resonant zero-cross current detection scheme. A novel type of high-power series resonant PWM inverter using Static Induction-Transistors and-Thyristors, which stably operates in a frequency range of 30 KHz to 100 KHz or more, is demonstrated for induction-heating and-melting, and DC-DC Converter. The simulated results and its performance characteristics in steady-state are described as compared with the experimental results.

A novel type induction-heating single-ended resonant inverter using new bipolar Darlington-Transistor

Demonstrated is a novel type of single-ended resonant inverter using a new Bipolar Darlington-Transistor that operates efficiently in the frequency range of 20kHz to about 50kHz. The inverter implementation for an induction-heating range includes a unique power control strategy. The analysis and performance evaluations for circuit design are carried out herein.

Reduction of vibration and acoustic noise in induction motor driven by three phase PWM AC chopper using static induction transistors

A three-phase pulse-width-modulated (PWM) chopper that uses a static induction transistor (SIT) to chop the three-phase AC voltage with a 20 kHz carrier frequency and control an induction motor is proposed. Harmonic components in the voltage and current waveforms do not appear in the audio frequency band with this method. When each terminal of the motor is connected to a 4 mu F capacitor, the terminal voltage and line current waveforms are almost sinusoidal. The motor speed is controlled by changing the on-time width of the gate signal. The power spectrum of the chopper-driven motor is calculated using a fast Fourier transform and measured. The results are used to reduce vibration and acoustic noise in the motor, which is confirmed by measurement. >

A general steady-state analysis program ANASP for thyristor circuits based on adjoint-network approach

Described is a new computer aided package program ANASP for computing the steady-state waveforms for any configuration of thyristor circuits. Newton-Raphson method is used to compute the initial state which generates the steady-state waveforms. For the efficient and accurate evaluation of the Jacobi an matrix the adjoint network is introduced into thyristor circuits containing power diodes and thyristors, and the method of sensitivity calculation is proposed. Using the program implemented, it is shown through examples that the computational time is considerably reduced to deter mine the steady state.

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.

A new computer-aided method of distortion sensitivity-analysis and its elimination scheme for power electronic circuits

A new general computer-aided algorithm for computing parameter sensitivities of distortion in power electronic circuits and its elimination scheme are proposed. The adjoint network approach is employed for calculating parameter sensitivities of the distortion factor and the ripple factor of current and voltage waveforms. An optimal filter design-algorithm to reduce undesirable harmonics is also proposed. Their performance is shown to be superior through demonstrated numerical examples.

Computer-aided analysis of power-electronic DC-motor drives: transient and steady-state analysis

Described are new and efficient computer-aided analysis packages for general power-electronic dcmotor drive systems. They compute both transient and steady-state waveforms for arbitrary field excitations and any thyristor configuration automatically. Users are only required to input circuit parameters, thyristor gate timing, machine constants and their connections in a free format.

A High-Frequency Resonant Inverter Using Current-Vector Control Scheme and Its Performance Evaluations

The authors introduce a new configuration of resonant-type high-frequency inverter having inherent fast control response of the output power and variable-voltage variable-frequency (VVVF) capability. The circuit is composed of a parallel combination of two series-resonant inverters with common input and output terminals. Both inverter units are operated at synchronous frequency and with an adjustable phase difference from 0° to 180°, allowing control of the output power from full to null power, respectively. Operation of this inverter is explained and computer-simulated operating waveforms and characteristic curves are shown in terms of normalized control variables and circuit parameters. A prototype inverter using Power MOSFET modules has been originally tested with a high-frequency induction heating and melting load to demonstrate experimentally the proposed control principle and the steady-state inverter performances under parallel tuned load conditions.