Abstract: Each working cycle of hydraulic excavator includes two swing actions, and frequent swing acceleration and braking result in a lot of overflow loss and throttling loss. Aiming at the problem that the existing energy saving technology of excavator swing system can not solve the problem of eliminating throttling loss and recycling and utilizing braking energy at the same time, a hybrid driving swing system is proposed, which uses permanent magnet synchronous motor as the main power source to drive the swing system of the vehicle, and the hydraulic motor-accumulator recycle and utilize the braking kinetic energy. This system effectively eliminates the throttling loss of the original hydraulic excavator through the multi-way valve, and recycles and utilizes the braking kinetic energy in the braking process. Based on the direct torque control of series motor, the control strategy that the start of swing process is accelerated by the motor and the hydraulic motor, and the braking process is braked by the hydraulic motor alone is realized. The research shows that compared with the original hydraulic excavator swing system, the peak power of the power source of the large electric excavator swing system can be reduced by 24%-32%, and the system energy consumption can be reduced by 14.1%-50.5%.

Key words: electric excavator, swing system, electro-hydraulic hybrid drive, peak power, system energy consumption