| 摘要 |
PURPOSE: To prevent commutation failure of each switching element by converting the voltage signal and the commutation voltage of each switching element to polar coordinates and calculating the control angle of each switching element based on the amplitude and phase difference of the commutation voltage. CONSTITUTION: The phase of, for example, a commutation voltage V1 detected by a commutation voltage detection means 11 and a voltage dial with a phase difference of 90 degrees are calculated and the voltage signal dtV1 and the commutation voltage Vl are converted to polar coordinates. Then, based on the conversion result, the amplitude √2.Vcoml of the commutation voltage V1 is calculated and at the same time the phase difference ϕcoml of, for example, the commutation voltage V1 for a reference phase is calculated. Also, based on the amplitude and phase which are calculated by an amplitude/phase difference operation means 12, for example, the control angle of each switching element is calculated by a control angle operation means 14. Then, each switching element is controlled according to, for example, the control angle which is calculated by the control angle operation means 14. |
