VAV control method and system of exhaust cabinet

The invention discloses a VAV control method and a system of an exhaust cabinet. Firstly, feedback control is performed by adopting window displacement, after the condition that the window displacement is increased by one level is detected, the excessive variable air volume delta V and the parking time delta t are calculated, the exhaust air volume of an air valve of the exhaust cabinet is adjusted to the set exhaust air volume V1 of the air valve, the excessive variable air volume delta V can be quickly increased, or the air volume of the air valve is reduced, so that the adjusting response speed of the air valve is high; then feedback control is performed by adopting the surface wind speed, the real-time surface wind speed of the exhaust cabinet is obtained in short parking time delta t,and the exhaust air volume of the air valve is adjusted according to the real-time surface wind speed of the exhaust cabinet, so that the real-time surface wind speed of the exhaust cabinet reaches the target surface wind sp