JPS558214A - Inverter control circuit - Google Patents

Abstract

PURPOSE: To retain equal radio waveforms of respective phases and readily switch the waveform shape of an inverter by synthesizing symmetrical triangular wave repeated in front and rear half periods and a standard value with a gate signal and controlling the number of pulses to the number of standard value.

CONSTITUTION: A signal 3072f obtained by the 3072 times of the inverter fundamental frequency f if applied to a 1/512 frequency divider 1 and an up and down counter 2. The frequency divider 1 thus produces its output signal of six times of the inverter fundamental frequency f, which is applied to a sexenary ring counter 3 and to the up and down counter 2 as an up and down instruction. The counter 2 produces upon reception of the input a triangular wave TRI. This wave TRI is applied to one input of a digital comparator 4. The comparator 4 receives at its other input information from a memory 5 to comapare the wave TRI with the information. The address of the memory 5 is determined by the output F of a frequency detecting circuit 6. The output of the comparator 4 is processed in a logic processor 7, which thereupon produces a modulation control signal L, which is then applied to a waveform synthesizer 8, which synthesizes the signal L with the input to the counter 3 to thereby produce a gate signal.

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