FILTER CIRCUIT FOR PWM INVERTER

摘要

PROBLEM TO BE SOLVED: To determine the constants of a reactor and a capacitor used for a filter only by the specifications of an inverter by decreasing the common-mode voltage of a carrier frequency component by a large extent, and decreasing the occurrence of loss caused by dumping. SOLUTION: A common-mode reactor 1 is inserted between a PWM inverter 11 and an AC motor driven by the inverter thereof. A three-phase star- connection reactor 3 is connected to the connecting point of the common-mode reactor 1 and the motor 12. A capacitor 2 grounds the neutral point of the reactor 3. These parts are provided. This is the filter circuit for the PWM inverter, wherein the resonant trequency by the common-mode reactor 1 and the capacitor 2 is located at the intermediate point between the output fundamental frequency of the inverter 11 and the carrier frequency and the inductance of the common-mode reactor 1 and the capacitance of the capacitor 2 are selected so as to be separated sufficiently from both frequencies.