Multivariable rotary hydraulic system and control method thereof

The invention belongs to the field of excavator hydraulic control, and particularly relates to a multivariable rotary hydraulic system and a control method thereof. The multivariable rotary hydraulic system comprises a rotary variable pump and a rotary variable motor, an upper oil port of the rotary variable pump is communicated with an upper oil port of the rotary variable motor, and a lower oil port of the rotary variable pump is communicated with a lower oil port of the rotary variable motor; a hydraulic control reversing valve is arranged between an upper oil port of the rotary variable displacement motor and a lower oil port of the rotary variable displacement motor, and a working oil port of the hydraulic control reversing valve is connected with a hydraulic oil tank; the closed hydraulic system consisting of the rotary variable pump and the rotary variable motor is also connected with the proportional electromagnetic valve; a working oil port of the proportional electromagnetic valve is communicated wi