| Traditional variable frequency/work frequency switching control systems only make frequency and turning (phase sequence) of AC motor identical switching around, as difference of AC power supply phases switching around, often can result in instantaneous impact of fluctuations of motor current and torque, this can bring serious impact to transducer, electrified netting, motor and load, produces harsh noise pollution, shorten equipment life at the same time, even leads to damage equipments.This paper studies a sort of the phase-locked synchronization control system of AC motor variable frequency/work frequency switching based on SOC (C8051F015). This study includes the major: (1) the frequency and phase detection of strong, weak electricity signals; (2) realizing the phase-pocked loop (PLL) which includes transducer control by C8051F series SOC; (3) completing the smooth switching control system by programming and system debugging. The paper designs one composition program which makes transducer as a tache of PLL; puts forward a new control method about the comparing of frequency/phase combination system by the switching way of time-sharing and make PI regulator replace the low-pass filter; Aimed at the problem that is the fundamental wave phase check of transducer output, we bring forward a new phase detection circuit and design parameters method of PWM wave.This system realizes intelligent software analysis judgment by SOC and periphery hardware, uses PLL close loop to make output frequency of transducer fulfill self-regulation, after output frequency and phase of transducer is the same as electrified netting, produces control instruction signals to make contactors switch, completes phase-locked synchronization control of variable frequency/work frequency smooth switching. By computer simulation and analyzing a great many of experimental results, the validity and feasibility of this systematic scheme and control circuit is verified. |
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