Research On The Energy Feedback Breaking Control System Of The Ship Loader Luffing Machanism

The shipment team of No.6company of Qinhuangdao port corporation, has fourmaterial taking machine(R), one taking and piling machine(SR) and three loadingmachine(SL), all of them are the main production equipment of No.6company, use veryfrequent. In coal loading and unloading process played an important role. The walkingcontrol system of the eight machines and the pitching control system of the SL all becompleted by the inverter.the system be comprised of the handle in the driver’s room,instruction relay, inverter, control relay, main contactor, drive motor, braking unit and thebraking resistance etc. they are braking all by braking energy, although the braking issimple, but has some shortcomings like waste energy, it’s hard to maintenance theresistance box、braking performance is not good etc. The faults led the braking to the smalland medium-sized system, who owns a small capacity like dozens of kilowatts. But eachof the machines we have owns at lest one hundred kilowatts. Especially the motor of theloading machine who owns two hundred kilowatts. So we can say that the braking we areusing now is not suitable for the drive system in the practical application.In order to further increase the electrical energy, optimization the inverter controlsystem function, realize saving, by analysis the original braking modes’ faults and theelectrical energy feedback braking system’s advantages and feasibility, we decided taketransformation for the part of pitch of the loading machine, designed the inverter’s energyfeedback system for the pitch port of the loading machine. The main contents include:Retain the brake units and the braking resistance of the original system, andadditional a set of energy feedback unit, by the actual situation decided to use the feedbackunit who belongs to jianengs’ IPC-PF series. Pick up the inverter’s dc bus with thefeedback unit’s imports, connect the feedback unit’s export with the grid, to realize thepower feedback. The voltage of feedback unit’s start-up more below than the brake unit’s.When produce the feedback energy in braking process, feedback unit start up first, andtake the redundant energy from dc bus to grid. When instantaneous energy is bigger, thespare parts will be consumed by the braking resistance. So as to ensure the security of thesystem. From real-time monitor the voltage of dc bus in the production process we can seethat the transformation system can take the huge renewable energy produced in slowing orbraking to the grid, the feedback rate can reach90%, and help the system realize fast brakeat the sometime.