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2

Analysing a drive system

Chapter outline
2.1 Rotary systems .............................................................................................................................. 38
2.1.1 Fundamental relationships................................................................................................. 38
2.1.2 Torque considerations ........................................................................................................ 42
2.1.3 Gear ratios ........................................................................................................................... 42
2.1.4 Acceleration without an external load............................................................................. 44
2.1.5 Acceleration with an applied external load..................................................................... 44
2.1.6 Accelerating a load with variable inertia......................................................................... 45
2.2 Linear systems............................................................................................................................... 46
2.3 Wheeled systems .......................................................................................................................... 46
2.4 Force based systems..................................................................................................................... 49
2.5 Friction............................................................................................................................................ 50
2.6 Motion trajectories ....................................................................................................................... 52
2.7 Assessment of a motor-drive system ......................................................................................... 56
2.7.1 Mechanical compatibility ................................................................................................... 57
2.7.2 Electromagnetic compatibility ........................................................................................... 58
2.7.3 Wiring considerations......................................................................................................... 59
2.7.4 Supply considerations ......................................................................................................... 60
2.7.5 Protection from the environment..................................................................................... 64
2.7.6 Hazards and risk.................................................................................................................. 65
2.8 Summary........................................................................................................................................ 71
References............................................................................................................................................. 71

To achieve satisfactory operation of any motion-control system, all the components
within the system must be carefully selected. If an incorrect selection is made, either in
thetypeorthe size of themotor and/or drivefor anyaxis, theperformance of thewhole
system will be compromised. It should be realised that over-sizing a system is as bad as
under-sizing; the system may not physically fit and will certainly cost more. In
the broadest sense, the selection of a motor-drive can be considered to require the
systematic collection of data regarding the axis, and its subsequent analysis.
In Chapter 1 an overview of typical applications was presented, and their broad
application requirements identified. This chapter considers broader issues, including the

Electric Drives and Electromechanical Systems. https://doi.org/10.1016/B978-0-08-102884-1.00002-9 37
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