| 摘要 |
PURPOSE:To reduce the overall size and cost by providing a circuit for detecting source voltage drop together with a circuit for detecting higher harmonic current contained in source current. CONSTITUTION:Output voltage detected through a current transformer 2 for detecting source voltage is inputted, simultaneously with detection of higher harmonic current Ish contained in source current Is, to a voltage drop detecting circuit 3 where a voltage drop V is detected. Voltage drops are then combined in a reference voltage forming circuit 6 thus producing a reference voltage Vc* = K.Ish- V from a voltage generating circuit 7. The reference voltage Vc* is then provided to a suppression pulse generating circuit 10 in the voltage generating circuit 7 where it is compared with a wave and subjected to pulse width modulation. The pulse width modulated signal is employed for switching of a switching element in a voltage type inverter which then provides a compensation voltage, proportional to the reference voltage, to the secondary of a current transformer 12. |
