| Abstract |
A novel three-level pulsewidth modulation (PWM) rectifier/inverter is proposed. The single-phase
three-level rectifier with power factor correction and current harmonic reduction is proposed to
improve the power quality. Three-phase three-level neutral point clamped (NPC) inverter is adopted to
reduce the harmonic content of the inverter output voltages and currents. In the adopted rectifier, a
switching mode rectifier with two AC power switches is adopted to draw a sinusoidal line current in
phase with mains voltage. The switching functions of power switches are based on a look-up table. To
achieve a balance DC-link capacitor voltage, a capacitor voltage compensator is employed to achieve
this goal. In the NPC inverter, the three-level PWM techniques based on the sine-triangle PWM and
space vector modulation are used to reduce the voltage harmonics and drive an induction motor. The
advantages of the adopted three-level rectifier/inverter are 1) the blocking voltage of power devices
(T1, T2, Sa1~Sc4) is clamping to half of the DC-link voltage, 2) low conduction loss with low
conduction resistance due to low voltage stress, 3) low electromagnetic interference, and 4) low
voltage harmonics in the inverter output. Based on the proposed control strategy, the rectifier can draw
a high power factor line current and achieve two balance capacitor voltages. The current harmonics
generated from the adopted rectifier can meet the international requirements. Finally, the proposed
control algorithm is illustrated through experimental results based on the laboratory prototype. |
