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The Relationship Of PLC Controller,Servo Drive And Load

Shenzhen ECON Technology Co.,Ltd | Updated: Aug 23, 2017

 The relationship of PLC controller,Servo drive and Load 


One,PLC controller frequency with servo drive and load speed



Known the servo drive Pm = 10000Pulse / r, PLC controller output frequency f (puls / s), how to calculate the load shaft speed n (r / s)


1.When the servo motor directly connect to the shaft, set the electronic gear ratio the molecular of the denominator for the N.


1.png


n=(f*N)/Pm ..........The unit of this formula is r/s,output pulse counts in 1s divided by one round pulse is one second running rounds


n :load speed,unit: r/s。


f :frequency from controller,unit:pls/s。


N:servo drive ratio。


Pm:,servo drive resolution,unit:Pulse/r。


2、Based on formula 1,Can be reasoned when the load shaft with a turntable or pulley, you can calculate the belt speed V


2.png


V=r*ω=r*2πn


Substituting Formula 1 :


V= πd ((f*N)/Pm)


d:pulley,load axis shaft,unit:mm。


n :load speed,unit: r/s。


f :controller frequency,unit:pls/s。


N:drive ratio。


Pm:drive resolution,unit:Pulse/r。


3、There are insufficient occasion at site,and use gear box condition,assume ratio to K

3.png


From formula 1,we know the output speed n of motor shaft,then can get gear box output speed n1。


n1=n/k=(f*N)/(Pm*K)...............r/s


n1=n/k=(f*N*60)/(Pm*K)...............r/min


Assuming n1 axis with slider,we can get the speed V of slider moving


V=n1*D=(f*N*D)/(Pm*K)............mm/s


Similar derived f=(V*Pm*K)/(N*D)


n :motor straigt axis speed,unit: r/s。


n1:add gear box output speed,unit: r/s。


K: gear box ratio。


V: slider moving speed,unit:mm/s。


D:screw lead,unit:mm




Two.PLC controller output pulse relationship with displacement


Based on above information,here take a detail discussion:


See below picture,servo drive Pm=10000Pulse/r,screw lead is(screw distance,explain to motor run one round,screw move a lead)D,PLC controller output pulse counts

is P, assume gear ratio is 1。

How to calculate the moving distance S of the corresponding working table?

4.png



4、S=(D/Pm)*P......First,get 1 pulse move disreplacement,times pulse counts to get the moving distance.If set the gear ratioN,then S=(D/Pm)*P*N....since P*N is the actual pulse

 that servo drive send to motor。


D:screw lead,unit:mm


P:controller output pulse counts,unit:pc


If following system,so how to calculate the distance of the movement? The mechanical part of the system is equipped with reducer,and ratio is K

5.png


5、S=(D/(Pm*K))*P*N.........same as 4,get 1 pulse move disreplacement,due to add gear box,1 pulse disreplacement reflect to load axis is smaller than 4.


It can be seen that the displacement is inversely proportional to the gear structure of the system reducer, and is proportional to the servo-drive electronic gear 

ratio.According to above formula,similarly, it also can get, if it is with a disc structure, the number of pulses corresponding to the angle of rotation of the disc,D=360 degree


Above 4,5 mentioned"get 1 pulse disreplacement",actual it is pulse equivalentδ。



Three.Pulse equivalentδ


Refer 4,5,(D/Pm)is the pulse equivalent without reducer,D/(Pm*K)add reducer system pulse equivalent.If the mechanical structure is determined, the value is

determined too, a pulse corresponding to the displacement is determined, that is, the accuracy of the system is determined. Such as 5mm lead screw,directly connect

with ECON servo drive, the accuracy is 5 / 10000mm. This system has a pulse equivalent of 5 / (10000 * 40) mm if the gearbox with a external reduction ratio of 40. 

Above determined parameters are called the system's intrinsic pulse equivalent.


Suppose it need to adjust the system precision to 1um / pls. What need to do? At this time the servo-drive electronic gear ratio came in handy.


Use below formula work out:


1:5*1000/(10000*40)=1:1/80=80:1,set servo drive gear ratio molecule P1-00 to 80,denominator P1-01 to 1。


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