The invention discloses a PWM variable spraying
system and a control method thereof. The PWM variable spraying
system comprises a
pesticide box, a variable spray head
assembly, a PWM variable spraying
control system, an intelligent center control platform, a spraying main pipeline, at least one spraying
branch pipeline, a
backflow pipeline, a
pesticide liquid pump, a control valve set, a collection
assembly and a pressure stabilizing filtering
assembly. And the control valve group comprises a main switch valve, a main pipeline switch valve, a
branch switch valve and a proportional overflow valve. According to the method, a three-layer measurement and control structure of'spray opening and closing circulation-pressure regulation and control circulation-flow regulation and control circulation 'is constructed, the
coupling effect of'pressure change caused by flow regulation and flow change caused by pressure regulation' is reduced, long-period and short-period cooperative scheduling is adopted, and the
recovery speed and the control stability under the state transition working condition are improved. And total spraying flow feedback is introduced to construct flow closed-loop correction, so that the spraying quantity control precision and robustness are improved.