Hydraulic control system for boom floating of excavator and control method thereof

A hydraulic control system for boom floating of an excavator, comprising a boom cylinder, a hydraulic circuit and a controller, wherein the hydraulic circuit comprises a main oil circuit and a pilot oil circuit, a main pump and a boom reversing valve are arranged on the main oil circuit, the main pump supplies oil to the boom cylinder through the boom reversing valve, and two working ports of the boom reversing valve are connected to a rod cavity and a rodless cavity of the boom cylinder respectively;

• a rod cavity floating valve is connected to an oil circuit between the rod cavity of the boom cylinder and the boom reversing valve, a rodless cavity floating valve is connected to an oil circuit between the rodless cavity of the boom cylinder and the boom reversing valve, and the rod cavity and the rodless cavity of the boom cylinder are connected to an oil tank through the rod cavity floating valve and the rodless cavity floating valve respectively;
• the controller is connected to a control terminal of the rod cavity floating valve, a control terminal of the rodless cavity floating valve and a control terminal of a floating pilot solenoid valve;
• a pilot oil pump and a handle pilot valve are arranged on the pilot oil circuit, an oil inlet of the handle pilot valve is connected to the pilot oil pump, and two pilot ports of the handle pilot valve are connected to two reversing control ports of the boom reversing valve respectively, wherein said end of the passage of the rod cavity floating valve is connected to the oil tank through an adjustable throttling valve.