| 摘要 |
PURPOSE:To reduce the cost of a pulse width modulation type inverter by using a relatively simple element such as a counter and an analog switch, etc. to produce a PWM control signal, thereby simplifying the circuit configuration. CONSTITUTION:A VCO1 outputs a pulse of frequency corresponding to the voltage level of the set value Fv of the output frequency and voltage of an inverter. This output is inputted to an up-down counter 2, and also to a counter 4 through a frequency divider 3. The outputs of counters 2, 4, an inverter 5 and voltage dividers 7, 8 are inputted to pulse width modulators 9U, 9V, 9W, which have analog switches 10-12 and comparators 13, 14. A distributor 15 applies a no control signal to the PWM signals from the modulators 9U, 9V, 9W, sorts and adds the PWM control signals of oblique positive and negative sides, and outputs a PWM control signal of a switching element of an inverter main circuit. |
