| 摘要 |
PURPOSE:To stably execute the overexcitation operation of the hysteresis motor by periodically opening a switch provided between a power supply and the motor for short time and closing it again to flow a current higher than the maximum value at normal time. CONSTITUTION:When the switch 2 is opened with an open command from a control circuit 4, a hysteresis motor 3 becomes free running state as isolated from a power supply 1. When the open command is released after predetermined short time to close the switch 2, sum of a normal current and transient current flows through the motor 3. Since the motor 3 has low input power factor and large time constant, the current becomes higher than the maximum value of the normal current. In this manner the magnetic flux density Bm of the rotor is increased higher than that before opening the switch 2 after reclosing the switch 2, but when the phase angle phi of the fundamental magnetic flux density wave of the rotor and the gap magnetomotive force is represented by phi, if the torque T represented by the formula T=KBmsin phi is constant, is reduced. Accordingly, the input power factor of the motor 3 is improved to reduce the input current. In this manner it can stably operate the overexitation operation of the motor. |
