Control strategy schematic and hybrid APF circuit diagram (compensation for harmonic current

Control strategy schematic (compensation for harmonic current)

As shown in the figure. The power supply current is closed-loop controlled, and the reference current and the actual current are output as the inverter voltage reference value after passing through the current controller. Then, the switching signal of the inverter is obtained by using the space vector modulation (SVPWM) technology to control the hybrid APF for harmonic compensation. The DC bus voltage control is achieved by adjusting the reactive current. The error between the DC bus voltage and the reference signal is generated by the PI controller to generate a control signal, and then the dq inverse transformation is performed. Finally, the voltage regulation signal is added to the current reference signal. If only the harmonic current is compensated, the phase φ(t) of the current reference can be directly obtained by sliding Fourier transforming the load current; if the harmonic and reactive current are compensated at the same time, φ(t) can be obtained by sliding Fourier analysis of the grid phase voltage.

Hybrid APF circuit diagram (compensation for harmonic current)

The circuit structure of the hybrid APF used to compensate for current harmonics is shown in the figure. The hybrid APF and nonlinear load (diode rectifier bridge with resistance and inductance load) are connected to the grid in parallel, and a harmonic current with equal amplitude and opposite phase is generated through the switching action of the IGBT to offset the harmonic current generated by the nonlinear load.