| 摘要 |
<p>PURPOSE: To improve the detecting accuracy by computing the effective value on the basis of the alternating current input voltage, which is detected in the input stage, and the PWM signal output from a PWM controller for controlling a switch element, and controlling the power on the basis of the effective value. CONSTITUTION: Alternating current input voltage effective value V1 Nerms is detected from the alternating current input voltage by using an absolute value circuit, a LPF 3 and an AMP circuit with the mean value method. At the time of computing D<1/2> , the serrate signal 1' synchronized with the PWM signal is input to an integrator so as to obtain the output signal 2'. This signal 2' is converted to a formula by level conversion, and input to one of comparators as the reference signal. The signal VPWMSV, which is obtained by meaning the PWM signal 3' with the level conversion and LPFI, is input to the other comparator. At the time of computing the effective value, V1 Nrms is input to the SW1, and the signal 7 is obtained by the ON/OFF control of the SW1 on the basis of the reversing signal of the signal 6, and the signal 7 is averaged by the LPF 2 so as to obtain the output signal 8. V1 Nrmsx D<1/2> as the effective value can be obtained on the basis of the signal 8.</p> |
