| 摘要 |
PURPOSE: To obtain an inverter which is constituted so as to simply detect a DC component in an inverter output voltage by providing a feedback circuit in which a certain amount is subtracted from a seine-wave command value by an arithmetic circuit, in which a DC portion in the intermediate potential between sine waves of its output and triangular waves is detected and in which an amount which has multiplied the DC portion to several tens of times is used as amount to subtract the sine-wave command value. CONSTITUTION: A sine-wave command value as the input signal of a comparator 7 and triangular waves are branched from the input side of the comparator 42. The sine-wave command value and the triangular waves take an intermediate potential, and only a DC portion in the intermediate potential is input to an operational amplifier 10 through a capacitor 13. Then, when the DC portion does not exist, the input signal of the operational amplifier 10 is 0. As a result, only when the DC portion exists, the DC portion is detected automatically, and a correction value signal is fed back to an operational amplifier 6 so as to be output. In the correction value signal, the DC portion in the sine-wave command value is subtracted by the operational amplifier 6, and the DC portion can be removed from a PWM signal. Consequently, a DC portion in the inverter output voltage can be corrected. |
