Masahiro Matsushima

Power-factor-corrected distortion-free constant-voltage constant-current AC power supply using variable capacitance devices

An entirely new hype of AC voltage/current regulator is proposed by the use of our original variable capacitance devices. This circuit theoretically makes no distortion of output waveform, because only linear reactance devices are utilized in the power stage. For output voltage/current control and input power-factor correction, two variable capacitance devices were employed as a linear capacitor. Two small boost-type DC-to-DC converters were used as a high-speed driver for these devices. These converters deliver no power in steady state. Input current of the proposed power supply becomes almost zero with the load shorted.

Analysis of an overload-protected current-feedback magnetic multivibrator

A detailed analysis is presented of our original overload-protected current-feedback magnetic multivibrator. Since current-feedback magnetic multivibrators are highly efficient and are suitable for high-frequency operation, they are widely used as power sources for electronic equipment. Unlike voltage-feedback multivibrators, however, their circuits have no ability to protect themselves from overloading. We therefore proposed a new current-feedback multivibrator with overload protection. In this paper, the conditions for cessation of oscillation are derived by using our model of bipolar junction transistors. This model takes account of power dissipation, because the common-emitter static forward current transfer ratio depends on the collector current and the junction temperature.

Overload-protected frequency-compensated current-feedback magnetic multivibrator

Current-feedback magnetic multivibrators are widely used as power sources for electronic equipment, because they are highly efficient and reliable. However, these circuits have no ability to protect themselves from overloading, and the oscillation frequency changes according to the load current. In this paper, we propose a new current-feedback multivibrator with overload protection and frequency compensation. In addition, the condition for cessation of oscillation and that for fixed frequency of oscillation are derived by analysis. These conditions can be determined independently of each other.

Current-feedback magnetic multivibrator with feedback-controlled frequency compensation circuit

An improved current-feedback magnetic multivibrator having a constant frequency of oscillation is proposed. Current-feedback magnetic multivibrators are noise-proof, reliable, and highly efficient. However, the frequency of oscillation varies with the load. The proposed multivibrator can compensate the oscillation frequency by feedback control. This circuit succeeds to advantages of self-excited multivibrators.

Higher-harmonic distortion canceller using a switching amplifier with minimum output power

A new feedforward-controlled higher-harmonic distortion canceller is presented in this paper. The input currents of electronic apparatus or industrial machines are pulsatile and contain many higher harmonic components, because capacitor-input smoothing circuits, phase-controlled rectifiers and so on are utilized. These higher-harmonic currents distort the line voltage waveform, and influence the equipment connected with the same line. The proposed circuit was composed by making use of our original noise superimposer, and decreased the total harmonic distortion from 5.07% to 0.34%.

Improvement Method of Input-Impedance Characteristics in Electronic Choke for Wire Communication System; -Effective Use of Electric and Magnetic Couplings in Inductor

Most wire communication systems utilize communication lines as power lines. The powered terminal needs to separate ac communication signals and dc supply power in its input part connected to the communication lines. In our communication system, it is preferable that the electronic choke be bidirectional. So, we have already proposed a low-loss electronic choke with small inductors and an amplifier. This circuit can be also used in the powering terminal. The electronic choke has high input impedance against communication signals. The frequency range of acceptable signals is determined mainly by resonance frequency of the inductors. In this paper, a method fitting this frequency range to the communication signal is proposed. To realize this, we introduce an inductor having new structure and external connection. By the effective use of electric coupling and magnetic coupling in windings, input impedance of the electronic choke is increased.

Analysis of an overload-protected frequency-compensated current-feedback magnetic multivibrator

A detailed analysis is presented of our original overload-protected frequency-compensated current-feedback magnetic multivibrator. Current-feedback magnetic multivibrators are highly efficient and are suitable for high-frequency operation. However, these circuits have no ability to protect themselves from overloading, and the oscillation frequency varies according to the load current. We therefore proposed a new current-feedback multivibrator with overload protection and frequency compensation. In this paper, the condition for cessation of oscillation and that for fixed frequency of oscillation are derived by using our model of bipolar junction transistors. This model takes account of power dissipation, because the common-emitter static forward current transfer ratio and the junction voltage depend on the junction temperature.