Research On Energy Recycling Speed Control System Of Grab Ship Unloader

Grab ship unloader is one of the main transport equipment in our country. It has been used in lots of habour in recent years ,because it is applicable for discharging different bulk cargo .With the development of carring trade ,demandment of stronger transport equipment become more and more .The habour corporations over the world demand more automatic large scale transport equipment which can save energy ,so they can enhance capability of competition .This paper is based on project which is aimed on modificating bridge-type grab ship unloader in Wisco .It pay more attention to research on energy recycling control system.For old unloader adopt dynamic braking mode when loading and discharging ,which waste big power ,we appeal to adopt energy feedback mode which can recycle energy .So we mainly do research on regenerative braking mode of bridge-type grab ship unloader ;According to its operating mode ,we probably estimate its retrievable energy ,find the key link for recycling power ,determine the scheme of composition about energy feedback system in bridge-type grab ship unloader--normal frequency converter plus dc-to-ac inverter .In this scheme ,frequency converter is in charge of electrical motor operation ,and dc-to-ac inverter preside recycling regenerative energy from electrical motor to power line .Thinking about electrical energy quality ,we also research on control strategy about three phrase PWM inverter .Through building up mathematic model of voltage mode inverter circuit ,we design its double closed loop control system--current inner loop and voltage external loop control .Finally ,we apply matlab to build emulation model of bridge-type grab ship unloader energy feedback system ;through the emulation result ,superior dynamic response and synchronizing ability with electrical line have been certificated .The research production has successfully been used in the project named"Bridge-type Grab Ship Unloader Modification Works",and acquire good effectiveness .It can supply successful experience to large-scale unloader modification works .In particular ,it can provide certain theoretical guidance and actual value of promotion to enhancing energy saving ability about bridge-type grab ship unloader.