Abstract: A DC-DC converter that has an AC link includes an input current type inverter and an output voltage type inverter coupled together by a transformer. The negative terminal of the current type inverter is connected in series with the positive terminal of the voltage type inverter. Controlled rectifiers are used in the current type and voltage type inverters and the angle, relative to a fixed point in the AC cycle, at which the controlled rectifiers are turned on and off is varied to obtain desired converter action. A substantially smaller transformer, thus, is required.

Abstract: An inverter device operating under pulse width modulation (PWM) principle in which chopping pulse is formed by crossing points of a triangle waveform and a function waveform in order that pulse width of the inverter input current decreases towards later half of pulse train in each period of pulse repetition series so as to make the average input current for each one of the pulses substantially constant.

Abstract: An inverter device operating under pulse width modulation (PWM) principle in which chopping pulse is formed by crossing points of a triangle waveform and a function waveform in order that pulse width of the inverter input current decreases towards later half of pulse train in each period of pulse repetition series.

Abstract: A rotary machine type quadruple frequency converter of which a stator is mounted with a primary and a secondary winding having a pole ratio of 1 to 4. The rotor is arranged to have the same number of poles as the number of poles of the primary winding. The rotor pole is arranged to have a shape for producing magnetic flux of 4th harmonics of the source frequency which is supplied to the primary winding. A quadruple frequency power is generated on the secondary winding operating the converter with the source frequency power.

Abstract: A treble frequency converter comprising a stator and a synchronously rotating rotor. The stator is provided with a primary winding connectable to a polyphase alternating current source and a secondary winding from which treble frequency power can be taken, the secondary winding having three times as many poles as does the primary winding. The rotor has the same number of poles as does the primary winding and the rotor poles are shaped so that the air-gap between the stator and rotor poles will serve to produce third harmonic flux waves effectively and economically.