Abstract: This system uses the digital control method to obtain the frequency and phase signal of the rotator induced emf. in a main motor. The step sine wave, then, is formed by technology of dislocation, frequency difference, counting, sine wave shaping etc.. This step sine wave can be used as trigger signal for SCR. Meanwhile, for carrying out the automatic control of the complete system, this invention uses the technology of amplitude-adjusting, phase-adjusting, property compensating, circulating current locking etc.. Hence, this invention is an apparently improvement of the current same type speed adjusting method, such as the misadjustment nearby synchronizing domain, the rotation instability in the undefined domain, the higher harmonic components, the power factor can not be adjusted automatically etc..
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