Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title A Novel Control Algorithm of a Three-phase PWM Inverter with LC Filter
Authors Kwang-Seob Kim ; Dong-Seok Hyun
DOI 10.6113/TKPE/2015.20.3.239
Page pp.239-246
ISSN 1229-2214
Keywords Three-phase inverter; PWM(Pulse Width Modulation); LC filter; FOC(Field Oriented Control)
Abstract A novel control method of a three-phase PWM inverter with LC filter is proposed. The transfer function of LC filter is the same as that of second-order low pass filter(LPF) , which has a zero damping ratio. A simple method of implementing second-order LPF with damping ratio is to add a resistor in an LC circuit. However, in a real power system, adopting damping resistors is impractical because it results in losses proportional to the square of the current flowing through the resistors. Instead of inserting resistors, the proposed control strategy utilizes the measured capacitor voltages to control the oscillation of LC circuit. The overall transfer function of the proposed method is the same as a second-order LPF, and its damping ratio is controllable via control variables. The current controller can have overshoots caused by LC filter. Improved current controller is implemented by an equivalent second-order of LC filter. A 7.5 kVA PWM converter and a PWM inverter with a 5.5 kW induction motor are set up to verify the proposed control algorithm. Test waveforms are also presented to verify the proposed LC filter control algorithm.