The frequency control system below condition of potential energy load is designed

95 above, at the same time leave out timing contactor, positive and negative turns the software such as contactor, solved a tradition completely to promote the inherent blemish of mechanical existence, make equipment performance goes great rise. 2, promotion machinery uses the timing character of potential energy load at promotion or drop potential energy is laden, no matter be to pass to balance or owe balance configuration, inevitable existence is dynamoelectric generate electricity with second birth two works area, its timing character if the graph is shown 2 times with the graph. Graph the timing that one rotor loop strings together resistor is characteristic 　 of 　 of 　 of 　 of 　 of 　 　 　 pursues if character of 2 communication frequency control pursues be shown, loop of rotor of electromotor of the type that wind a string is strung together when receiving resistor timing, pass resistor classification switch and positive and negative turn contactor switch, timing of solid existing level and positive and negative turn control. Among them, working place １ and job are nodded 2 for dynamoelectric condition, the job is nodded 3 for condition of apply the brake of specific power consumption, the job is nodded 4 for condition of second birth dynamo. Frequency control character is a group of parallel curves, it is OK to be the same as the frequency at transducer successive and adjustable, can implement flowing stepless speed regulation consequently. Graph 2 in １ area is electric division, 2 area generates electricity for second birth area, electric energy passes on the dc side to transducer, carry release of component of apply the brake. 3, when the capacity of transducer chooses to promote machinery to use transducer to undertake controlling, can change uses squirrel cage motor, mechanical to using the promotion of electromotor of the type that wind a string formerly, can receive the rotor weak point of electromotor of the type that wind a string, regard as basket model electric machinery is used. Commonly used electromotor circles line electromotor for YZ series squirrel cage electromotor and YZR series, the electromotor of these two series, it is with duty S3 and load lead the norm of 40% to serve as fiducial norm continuously. After the rating make choice of of electromotor, should choose corresponding transducer capacity. The overload moment of force of YZ and YZR series electromotor is commonly 2.

2-2.

8 times, to develop the laden ability of electromotor adequately, improve the safety performance that has heavy facility, after using transducer to undertake controlling, must assure transducer - electromotor system is had 2.

2-2.

The overload ability of 8 times. Because the overload ability of common transducer is a minute 150% commonly, moment of force of transient state overload can be achieved only 180% - 200% , because this must raise place comfortable fit transducer capacity, so that raise transducer - the instantaneous overload ability of electromotor system. By afore-mentioned knowable, should increase the size of transducer only 20% the left and right sides, can make transducer - the instantaneous overload ability of electromotor system rises 2.

0-2.

4 times, satisfy a requirement basically. Accordingly, should choose transducer nominal capacity to be the 120% above of electromotor nominal capacity, increase the size of transducer namely a grade. Be like the electromotor of 45KW, should configure the transducer of 55KW, and transducer should have larger overload capacity, overload rate is in a minute of 150% above. 4, of component of apply the brake reasonable if the graph is shown 3 times,choose, the mechanical energy when second birth generates electricity is changed into electric energy, on the capacitor that passes on transducer dc side, its will make the voltage of dc loop elevatory as a result, lift when voltage some set is worth (like 750V) , discharge of automata of unit of apply the brake guides with switch canal, electric energy to the release on resistor of apply the brake. After motion of unit of apply the brake, the energy of release is more than pass on energy, the electric grave of dc loop begins to drop, drop to establish one value to some when it (like 630V) , criterion discharge of automata of unit of apply the brake uses switch canal to shut, stop to discharge. This charges to be finished automatically by transducer and component of apply the brake with discharge process, maintain dc loop voltage to be in a safe limits. By afore-mentioned knowable, the basic principle that chooses component of apply the brake is: 1, the energy of discharge of the biggest instantaneous of component of apply the brake is more than be equal to the biggest instantaneous to pass on energy. 2, the average discharge energy of component of apply the brake is more than be equal to pass on energy on average. Normally, the place of rated electric current that by its discharge switch runs decides the capacity of discharge of the biggest instantaneous of component of apply the brake, and average discharge ability depends on the rated power size of resistor of apply the brake. With the industrial and mining enterprises commonly used travel condole is exemple, show component of apply the brake choose a method. Graph sketch map of system of 3 frequency conversion pursues the 4 travel condole that are a model operating speed graph. Travel condole promotes a heavy thing with speed N1 in a certain place, translation goes to another ground to nod, next with clog of speed N1 transfer to a lower level, farewell continues to work to place, such move back and forth. Set working cycle to be T, when clog of transfer to a lower level electromotor second birth generates electricity, duration is T ｂ , the laden torsion that the clog forms on electromotor axis is M ｚ , mechanical efficiency is η , criterion: The biggest instantaneous passes on ｂ of T of time of apply the brake of 　 of MzN1 of energy Pm= η inside pass on 　 of MzN1 of η of ＝ of energy P ｂ on average inside periodic T pass on MzN1Tb/T 　 of η of ＝ of energy P ａ on average to press the rated parameter that does algorithm to choose package: 1, discharge switch is in charge of 　 of Ibe>Pm/750 of 　 of 　 of Ibe of rated electric current to press ＝ of Mz of normal overload condition 1.

5Me, n1=Ne will consider, take Ibe>1.

5 η MzNe/750=1.

5 η Pe/750 　 among them, me, Ne, Pe is the rated torsion of electromotor, rated rotate speed and rated power respectively. 2, resistance of apply the brake ≈ of Rb of 　 of Rb 　 　 (750-800)/Ibe(Ω ) 　 3, the permission of resistor of apply the brake of 　 of Pbe of rated power of resistor of apply the brake the function that overload coefficient K is time, its typical characteristic curve is shown 5 times like the graph. Make by 　 of Pe(Tb/TXMzN1/MeNe) of η of MzN1Tb/T= of η of Pa= of 　 of 　 of 　 of Pe(MzN1/MeNe) of η of Pb= η MzN1= K1=MzN1/MeNe, make for K2=Tb/T of coefficient of load of apply the brake, call make rate, criterion 　 of 　 of K1K2Pe 　 of η of ＝ of Pa of 　 of Pb= η K1Pe is calculated according to operating condition a Pa and Pb, and the overload coefficient Kb from fish of curve of character of resistor of apply the brake and Tb correspondence (it is a standard with the environmental temperature of 40 ℃ ) , consider certain safe size at the same time, choose Pbe>1.

2Max(Pb/Kb, pa) 5, the rate that timing controls a method to use frequency control pilot to promote machinery to still can use a convention controls a method, if the speed of travel condole is controlled, still use traditional cam controller, different archives gave out to rise or drop directional instruction and multistage speed instruction, input the control end of transducer, realize directional control and timing. There already was a condole frequency conversion now special controller is rolled out, apply it to be able to simplify control system design, reduce breakdown point. Frequency control implement still can offer more first yes closed-loop control method, if cooperate craft,implementation promotion and descendent different rate move etc. Lifting platform of rolling mill of some steel ironworks uses frequency conversion transmission, balance the cooperative control of the orgnaization to realize electromotor and fluid hardness, the control technology with advanced application realized the gearshift below different balance moment of force to control, fluid hardness was solved to balance cold starting problem of the system below the circumstance that does not increase transducer size. 6, the design of frequency control system below condition of load of last word potential energy must be a basis with actual and laden circumstance, ability achieves the goal of economic investment. Of component of electromotor, transducer, apply the brake reasonable match the key that is a design. In designing methodological application to wait for many frequency conversion to transform a project at lifting platform of overhead traveling crane, tower crane, rolling mill originally, got favorable result. Company of Guangzhou steely group transforms even frequency conversion of overhead traveling crane of 20t of make friends factory, because the design is reasonable, saved investment already, what assured overhead traveling crane again is basic moving function, equipment investment moves more than one year, the case is good, did not produce any breakdown. CNC Milling CNC Machining