| 摘要 |
PURPOSE:To contrive to form the power factor detector of a load to be driven by an inverter in a small size by a method wherein a voltage between the base and emitter of a transistor is compared with the prescribed value to obtain a transistor current feeding signal, and the phase difference between the signal thereof and an intermittent control signal is detected. CONSTITUTION:The voltage between the base and emitter of the transistor at the inverter is detected, and the detected value thereof is inputted to a comparator COM, and is compared with the prescribed value to obtain the transistor current feeding signal. The transistor current feeding signal thereof is differentiated in a differentiating circuit D and is inputted to a phase difference detector PD, while the intermittent signal of the transistor is differentiated in a differentiating circuit D and is inputted to the phase difference detector PD, and the phase difference between both is detected. Output of the phase difference detector PD is led out through a filter F to obtain a power factor signal. |
