| 摘要 |
PURPOSE:To suppress ripples contained in output by suppressing the change rate of total phase instruction, which controls the output current of a converter equipped with a smoothing reactor on the DC side of the converter, below a specified value. CONSTITUTION:An AC power source 1 is converted into DC with a converter 3, and drives an inverter through a reactor 4, and generates VVVF so as to rotate a motor 7. A power source synchronous signal 13 and the difference between a detected 8 DC current i1 and a current instruction value i1 are input into a microcomputer 11. A function unit 100 makes up a phase instruction theta*and a conduction ratio instruction gamma*. A normal processing means F1000 calculates the phase instruction theta* and the conduction ratio instruction gamma*, and secondly calculates a total phase instruction theta*r. The change ratio of theta*r is checked and suppressed below a specified value. Next, the order and the timing of extinguishing and firing of main switching elements 31-36 are set and output to a converter 3. Hereby, ripples are suppressed, and torque ripples and noise are prevented. This is suitable for use in an elevator. |
