| 摘要 |
PURPOSE:To simplify the controlling circuit for an inverter and to enhance the conversion efficiency by calculating the output of a ring counter and the output of a converter to obtain continuous PWM waveform. CONSTITUTION:An output frequency instructing unit 1 produces a voltage signal corresponding to the frequency to be outputted from an inverter, and a V/F converter 2 converts the voltage signal into a frequency signal. This frequency signal is counted by a counter 3, and the counted value from the counter 3 is inputted to a sexanary ring counter 4, a converter 5 and an up-down converter 6. The output of the counter 4 is inputted to an inverter controlling circuit. The converter 5 is formed of exclusive OR logic circuit, which produces a switching signal. The output of the converter 6 designates the addresses of the ROMs 7, 8 to produce pulse modulation output in accordacne with the pulse width modulators 9, 10 to the switching circuits 11, 12. |
