| 摘要 |
PROBLEM TO BE SOLVED: To significantly save power consumption without reduction in amount of the wind within the constant range of voltage in a blower, using a three-phase induction motor. SOLUTION: The three-phase induction motor operates mostly within rated values. In this case, when an input voltage is lowered, an excitation current (stator field) is increased, but the input power is not reduced. However, since a blower feeds wind with blades, when the number of revolutions is low, resistance is small, and when the number of revolutions increases, this resistance is also increased. Namely, higher drive torque is not required. Moreover, the torque will not change, to a large extent during rotation; and when the number of rotations is constant, even if the input voltage is lowered, the number of rotations will not change largely and an excitation current does not increased. As a method of lowering the voltage, a reactor is inserted, in series with the blower to lower the voltage applied to the motor of blower, and thereby an input voltage can be lowered. The voltage is reduced in the range of about 0 to 30% of the rated power supply. If the voltage lies within this range, changes in the number of revolutions are small. |
