Project Three
MOTOR SPEED CONTROLLER
Ewan, Dave, Mitch, Simon, James and Chris
Background Motor Control
 DC Series Motor.
 Can be used for a variety of Industrial applications.
 Pumps
 Electric Trains
 Motor control achieved through varying terminal
voltage across the motor armature.
Series DC motor Circuit [1]
DC series type motor [2]
Background Siemens PLC
 S7-314C_2DP
 Industrial type PLC
 Middle of the range model
 Two S7’s were used for this project to act as a
controller and process.
Siemens S7-300 [3]
PLC’s of the Past
 Controller for Ferag Publishing Winder
 TTL and wire wrapped pins
 Siemens Controller
circa 1980
Background HMI
 TP177B-PN/DP 6”
 Discontinued model
 Ability to adjust outputs and read
operating conditions
TP177- Siemens HMI [4]
Objectives
 Utilise two Siemens PLC’s. (Controller and Process)
 Utilise PID control for the Process in TIA.
 Set point tracking
 Compensation load variations on the motor
 Additional Objectives:
 Correctly operating visual indicators through the HMI
 Delivery as a single multi-PLC project
Design: Overall Design
Controller and Process Design
Design: Initial Planning
 Identified early that planning would be extremely
important for managing 6 team members.
Differing programming styles
 Strengths and weaknesses

 Project leader nominated.
 The group decided on modelling a DC series motor.

Identified metrics for a successful simulation.
 A Gantt chart was used so all team members knew their
roles and responsibilities.
Controller PLC
 Process PLC
 Report and Documentation
 PID block
 HMI

Design: Process Model
 Process model was created in Simulink as a second
order system.
 A second order was selected because its response
most closely represents a typical motor speed curve.
• Initial slope of zero.
• Initial response of zero.
• Simulates the motor ‘lag’ in
response to a set point
change.
A second order response
Design: Process Model
 Discretised using Euler approximations.
 This was done because it enables easy manipulation
of gain, natural period and damping coefficient.
 The result of the Euler method was programmed in
TIA by utilising math blocks.
 Noise was simulated through the use of multiple sine
waves added to the final output.
 Load was simulated by the addition of a first order
disturbance to the output.
Design: Controller
 Second order system response was controlled in the
S7 using the standard PID block.
 The PID was originally used to achieve the desired
response.
No steady state offset
 Quick response
 No overshoot

 The PID was used to accommodate the
implementation of disturbance.
 The controller PLC also managed the extra functions
through use of the HMI.
Design: Entire Process
Simulink Model of Entire System
Design: HMI
 Interact with Controller PLC
 Monitor speed and controller response
 Manipulate set point
 Indicate fault status
 Communication over MPI
 Piggy-back off PLC
 Transfer over Ethernet
 Orders of magnitude faster than MPI
 Substantial difficulty
commissioning
Results
 Overall, system performed well.
 Simulated process adequately.
 Controller responded appropriately.
 HMI allowed for enhanced control.
 Responded as desired under all test conditions.
 Emergency stop and system reset
 Adding and shedding load:

Over and under speed responses.
Improvements
 Additional testing/tuning of PID block to increase
robustness.
 Increased safety measures and further condition
monitoring.
 PLC Interfacing over MPI or Profibus instead of
using digital and analogue I/O.
 Fault Screens on error.
Questions
References
 [1]DC series Motor Circuit. Online: http://electrical-engineering-
portal.com/4-types-of-dc-motors-and-their-characteristics .
Accessed:7/6/15.
 [2] DC Series Motor.
http://www.globalspec.com/reference/42926/203279/shunt-seriesand-compound-motors . Accessed: 7/6/15.
 [3] Siemens S7-300. http://www.nexinstrument.com/CPU-314C-2DP6ES7314-6CH04-0AB0_p_69.html . Accessed: 7/6/15.
 [4] TP177 HMI. http://www.comeon365.com/ProductInfo5165.html .
Accessed: 7/6/15.