| 摘要 |
PURPOSE:To make a motor rotate with a constant torque by a method wherein a voltage ripple created in a DC output of a converter is added to a modulated wave and the modulated wave components having wave heights exceeding a predetermined wave height are limited to obtain the modulated wave having almost identical wave heights and the modulated wave is compared with a carrier wave to obtain the control signal of an inverter. CONSTITUTION:A modulated wave signal given from a modulator circuit 3 which creates the modulated wave from a voltage instruction V* and a frequency instruction f* is added to a DC voltage waveform signal given from a filter circuit 1 and the resultant signal is inputted to a limiter circuit 5. After the modulated wave components having high wave heights are limited by the limiter circuit 5, the limiter circuit 5 outputs the modulated wave to a comparator circuit 6. A carrier wave given from a carrier wave circuit 2 and the limited modulated wave which is limited by the limiter circuit 5 are compared with each other and the result of comparison is outputted to an inverter INV as a gate control signal. With this constitution, the output voltage of the inverter INV can be controlled to be constant without being influenced by the ripple of the DC voltage. |
