Output feedback decoupling-based low switching frequency control method for PWM converter

The invention discloses an output feedback decoupling-based low switching frequency control method for a PWM converter, and belongs to a control method for the PWM converter. The method comprises the steps as follows: by a double closed-loop control, a phase-locked loop unit obtains a grid voltage vector angle theta to achieve coordinate transformation; an outer voltage loop controls a direct current side capacitor voltage of the PWM converter, and a set value, as shown in the specification, of a d axis of a grid-side current output by the outer voltage loop, and the set value, as shown in the specification, of a q axis of the grid-side current are taken as inputs of an inner current loop; reference voltages, as shown in the specification, obtained by the inner current loop are subtracted from grid voltages e and e , then decoupling compensation voltages u and u obtained by an output feedback decoupling unit are subtracted from the grid voltages, and the result is taken as modulation voltages as shown in the specification; and finally a power device control signal s of a drive converter is obtained by a space vector pulse width modulation. According to the output feedback decoupling unit disclosed by the invention, system coupling caused by a time delay can be eliminated at a low switching frequency; a relatively good decoupling control can be obtained under the conditions of a system steady state, a sudden load change and a voltage jump; and the control performance of the system is improved.