| 摘要 |
The present invention relates generally to the reduction of odd harmonics of phase angle controlled loads. One embodiment relates to an apparatus for reducing odd harmonic currents introduced into an alternating current (AC) supply by a load having a zero crossing detector and a processor coupled to the zero crossing detector. The zero crossing detector is coupled to the AC current supply for measuring voltage zero crossings of the AC current supply. The processor receives a user control signal for controlling the load, such as, for example, a speed control, determines phase angles required at the voltage zero crossings of the AC current supply to implement the user control signal, and selectively modulating the phase angles when they are in a predetermined range of undesired phase angles in order to selectively reduce odd harmonics within the AC current supply.
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