Research on the flow-coupled hydraulic transmission with secondary regulation converting hydraulic energy to electrical energy

摘要

This paper presents flow-coupled hydraulic transmission with secondary regulation using two identical SPWM IGBT bridges as converter and inverter given four full quadrant control capabilities in a cylinder driven hydraulic load for electricity regeneration and generation.. During motoring, hydraulic oil is supplied to the cylinder which pulls the counter weight downwards to lift up the weight while during regeneration (down stroke), the induction motor acts as a generator and returns a near sinusoidal current to the mains/grid. At this point, the speed of the induction motor rotor begins to turn faster than the synchronous speed set by the drives output, converting mechanical power available in the induction motor shaft into electrical energy which is fed back to the power line. The discharge of the pump/motor can be adjusted either by the pump displacement controller or the inverter which controls the induction motor speed and the motion of the driven load is sensed by the encoder, which is mounted at the beginning and the end of the cylinder rod length. The output of the encoder is decoded and fed back to the personal computer via an interface card. The system simulation is done with Mathlab/Simulink. Experimental result proves that the system is effective in energy generation and regeneration.