| 摘要 |
PURPOSE:To reduce a surge voltage by superposing drive signals of transistors at a predetermined electric angle between phases, continuing currents to continue a regenerative current, and reducing a DC voltage rise at regenerative time. CONSTITUTION:Power from an AC power source 1 is supplied through a converter 3 and an inverter 4 to an AC induction motor 8. A controller 7 supplies drive signals 5, 6 to the converter 3 and the inverter 4, respectively. The drive signals 5 of transistors CTR1-CTR6 on the converter 3 are widened more than a zone 120 deg. (electric angle) that rectifiers D1-D6 are conducted from the phase slightly ahead of 30 deg. electric angle to the phase slightly behind 150 deg. electric angle width the phase voltage of the power source 1 as a reference, and the zone that the adjacent phases are superposed is provided.
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