1 2 34 5LCL filter contactor1LCL filter2Line-side converter3DC capacitors4DC link5AC voltage and current waveformsThe AC current is sinusoidal at a unity power factor. The LCL filter suppresses the ACvoltage distortion and current harmonics. The high AC inductance smooths the line voltagewaveform distorted by the high-frequency switching of the converter. The capacitivecomponent of the filter effectively filters the high-frequency (over 1 kHz) harmonics.ChargingCharging is needed to power up the DC link capacitors smoothly. Discharged capacitorscannot be connected to the full supply voltage. The voltage must be increased graduallyuntil the capacitors are charged and ready for normal use. The drive contains a resistivecharging circuit consisting of fuses, contactor and charging resistors. The charging circuitis in use after start-up until the DC voltage has risen to a predefined level.￭ Motor-side converterThe motor-side converter converts the DC back to AC that rotates the motor. It is also ableto feed the braking energy from a rotating motor back into the DC link. The motor-sideconverter is controlled by a type CCU-24 control unit. This is called the drive control unit orcontrol unit in this manual.Operation principle and hardware description 27
