The invention discloses a
current source type PWM (Pulse-Width Modulation)
rectifier and a grid-connected control method based on a virtual
resistor. A grid-connected
rectifier consists of commercial power, an alternating-current filtering
inductor, an alternating-current filtering
capacitor, a three-phase
current source type
rectifier, a direct-current
inductor, a direct-current
capacitor and a digital controller. Sampled alternating-current filtering
capacitance voltage is transmitted to a
microprocessor to perform digital
phase locking, and after
phase locking is finished, the alternating-current filtering
capacitance voltage and phase are transmitted to an alternating-current controller. The alternating-current controller consists of a coordinate converter, a
virtual impedance regulator and a divider. The coordinate converter converts the three-phase alternating-current filtering
capacitance voltage into the voltage under a two-phase static coordinate
system, after the voltage is regulated by the virtual resistance
regulator, current passing through a virtual
resistor is obtained, control amount of the alternating-current side is obtained through the divider, the control amount is superposed on the control amount on the direct-current side, a driving
signal obtained through a PWM generator is transmitted to a driving plate, and after the
signal is amplified by the driving plate, the connection and disconnection of a three-phase
current source type rectifying bridge switch are controlled. The
control effect of the virtual resistance
regulator in the alternating-current controller is equivalent to the
control effect that a
resistor is directly connected in parallel on an alternating-current
capacitor, so that oscillation can be effectively damped, loss is not caused, and ultraharmonics in grid-connected current can be effectively inhibited. The rectifier is high in dynamic response speed, stable in dynamic response and high in
power factor, the
total harmonic distortion rate of the grid-connected current is low, and the method can be applied to an
uninterruptible power supply.