| 摘要 |
A power converter which drives a high-voltage AC motor at a variable speed. A conventional inverter system has such problems that the system cannot cope with technical tasks required by the market such as the energy and resource saving for environment conservation, miniaturization, higher efficiency, and suppression of distortion of voltage and current waveforms, and the system cannot cope with a technical task to improve the redundancy such as the operation of the system with a sound part when a fault occurs. This power converter is a multiplex three-phase pulse width modulation cycloconverter and drives a high-voltage motor (10) at a variable speed by controlling two-way semiconductor switches (11-16) by a pulse width modulation so that the voltages of AC ouputs outputted to the single-phase AC terminals (u and v) of three-/single-phase pulse width modulation cycloconverters (1-9) are in phase in the same unit and the electrical angles of the fundamental wave voltage phases of the three units are shifted by 120~ from each other. When one of the cycloconverters (1-9) fails, the motor (10) is driven at a variable speed by short-circuiting the single-phase AC terminals (u and v) of the faulty cycloconverter and successively short-circuiting at regular intervals the three pairs of two-way semiconductor switches respectively connected to the three-phase AC terminals (r, s, and t) of the cycloconverters of the other tow units, belonging to the same group as that of the faulty cycloconverter. A current converting method is also disclosed. |
