| 摘要 |
PURPOSE:To effectively utilize a memory by writing necessary data for obtaining a PWM wave in a memory having an address corresponding to an angle width divided from one period of the PWM wave in duplicated state. CONSTITUTION:A DC power source 2 is converted by a 3-phase inverter 1 formed of transistors Q1-Q6 of a switching element as 3-phase AC of pulse- width-modulation (PWM) wave, and supplied to a 3-phase load 3. To obtain the PWM waveform, data necessary therefore is written in an ROM 4 of 8 bits, this is read out by an address circuit 5 to control to drive the transistors Q1-Q6 through a selector 6 and a 3-phase PWM wave forming circuit 7. In this case, a plurality of data are written in the same address of the ROM 4 to write the data corresponding to the angle width smaller than 180 or 360 deg.. Since each address has 8 bits, a plurality of data can be simultaneously read out, but only necessary data are selected to form the PWM wave. |
