The document discusses computer-aided design (CAD) methods for electrical machines, including analysis, synthesis, and hybrid approaches, emphasizing the importance of computer programs for managing high variable counts in design. It introduces the finite element method (FEM) as a numerical technique for solving complex engineering problems and highlights its historical development and advantages in design optimization. The content also outlines input data requirements, various design parameters, and the role of FEM in enhancing engineering methodologies and reducing product development time.

1. Computer-Aided Design of Electrical
Machine

2. Computer-Aided Design
• Introduction to computer aided design.
• Analysis and synthesis methods -hybrid techniques.
• Introduction to Finite element method - historical background,
applications, advantages.
• Study of new computer aided machine software using Finite Element
Case study:
• Complete design of an ac machine –steps.(Assignment only)

3. Computer-Aided Design
• In any practical design the number of variables is so high that hand
calculations are impossible.
• The number of constraints is also large and for these to be satisfied by
final design, a lengthy iterative approach is required.
• This is only possible with the help of computer programs (refer
Flowchart I. J).

4. Computer-Aided Design

5. Computer-Aided Design
A
A
B
B

6. Computer-Aided Design
❖ Explanation of Details of Flowchart
1. Input Data to be Fed into the Program
2. Applicable Constraints I Maximum or Minimum Permissible Limits
3. Output Data to be Printed after Execution of Program
4. Various Objective Parameters for Optimization in an Electrical Machine
• Input Data to be Fed into the Program
• a) Data
• b ) Applicable curves in array format
• c) Applicable tables in array format like

7. Computer-Aided Design
• Explanation of Details of Flowchart
• Input Data to be Fed into the Program
a. Data
1. Rating of the machine (KW/KVA)
2. Rated Voltage
3. Rated Frequency (for AC only)
4. Rated Speed (RPM)
5. Type of Connection of Phases
(Star/Delta) for 3 ph AC only
6. Type of Winding (Lap/Wave)
7. Number of Parallel Paths
8. Shunt/Compound in case of DC Machine
9. Squirrel Cage/Slip Ring type for 3-ph Ind.
Motor
10. Rated Slip /Rotor speed for Ind.Motor
I1. Salient Pole/Round rotor type for 3-ph
Alternators
12. Rated power factor for 3-ph Alternators
13. Core/Shell type for Transformers
14 . Ratings of HV /L V for Transformers

8. Computer-Aided Design
• (b) Applicable curves in array format like,
• B/H for magnetic materials used for Core, Poles,
• 2. Loss Cuves for magnetic materials
• 3. Hysteresis loss vs. frequency
• 4. Carters coefficients for slots and vent ducts
• 5. Apparent Flux density
• 6. Leakage Coefficien~ of slots
• 7. HP ys. output coefficient for I-ph Ind.Motor

9. Computer-Aided Design
• Applicable tables in array format like,
• I. Output vs. Specific Electric Loading(q)
• 2. Output vs. Specific Magnetic Loading(Bav)
• 3. Output vs. AT/pole
• 4. No. of poles vs. Pole pitch
• 5. Depth of Shunt field winding vs. Arm Dia
• 6. Standard sizes of brushes
• 7. Powef·-Factor and Efficiency at different ratings of Ind. Motor
• 8. Frequency vs. Frequency constant of I-phlnd. Motor
• 9. No. of poles vs. DiiDe ratio for I-ph Ind. Motor
• 10. Efficiency and PF vs. output for I-ph In9._ Motor
• II. Thickness of Stator winding ins vs. Voltage for Rotating machines
• 12. Window space Factor vs. K V A for transformers.
• 1

10. Computer-Aided Design
• Computer aided design – Three approaches
• Analysis method
• Synthesis Method
• Hybrid Method

11. Computer-Aided Design
• Analysis method
• Choice of dimension , type of material and type of construction are
made by the designer and these are presented to the computer as the
input data
• The performance is calculated by the computer and is return to the
designer to analysis
• The designer analyze the performance and make another choice of
input if necessary and the performance is recalculated
• This procedure is repeated till the performance requirements are
satisfied

12. Computer-Aided Design
• Analysis method

13. Computer-Aided Design
• Analysis method – Advantages
• It is fairly easy to program to use and to understand
• Time saving
• Simple programs
• The results are highly acceptable by the designers

14. Computer-Aided Design
• Synthesis Method

15. Computer-Aided Design
B
B
A
A

16. Computer-Aided Design
• Synthesis Method
• The desired performance is given as the input to the computer
• The logical decisions required to modify the values of variables to arrive
at the desired performance are incorporated in the program as a set of
instructions
• Advantages
• Saving in time
• Dis – advantages
• Complex program
• Calculation cost is high

17. Computer-Aided Design
• Hybrid Method
• This method include both analysis as well as synthesis method in the
program

18. Introduction to Finite Element Analysis
• Introduction to Finite Element Analysis
• The Finite Element Method (FEM) is a numerical technique to find approximate
solutions of partial differential equations.
• It was originated from the need of solving complex elasticity and structural analysis
problems in Civil, Mechanical and Aerospace engineering.
• FEM allows for detailed visualization and indicates the distribution of stresses and
strains inside the body of a structure.
• Many of FE software are powerful yet complex tool meant for professional engineers
with the training and education necessary to properly interpret the results.
• Several modern FEM packages include specific components such as fluid, thermal,
electromagnetic and structural working environments.
•
•

19. Introduction to Finite Element Analysis
• Introduction to Finite Element Analysis
• FEM allows entire designs to be constructed, refined and optimized before
the design is manufactured.
• This powerful design tool has significantly improved both the standard of
engineering designs and the methodology of the design process in many
industrial applications.
• The use of FEM has significantly decreased the time to take products from
concept to the production line.
• One must take the advantage of the advent of faster generation of personal
computers for the analysis and design of engineering product with precision
level of accuracy.
•

20. Introduction to Finite Element Analysis
• Background of Finite Element Analysis
• The finite element analysis can be traced back to the work by Alexander Hrennikoff
(1941)and Richard Courant(1942).
• Hrenikoff introduced the framework method, in which a plane elastic medium was
represented as collections of bars and beams.
• These pioneers share one essential characteristic: mesh discretization of a
continuous domain into a set of discrete sub-domains, usually called elements. • In
1950s, solution of large number of simultaneous equations became possible because
of the digitalcomputer. • In 1960, Ray W. Clough first published a paper using term
“Finite Element Method”. • In 1965, First conference on “finite elements” was held.
• In 1967, the first book on the “Finite Element Method” was published by
Zienkiewicz and Chung. • In the late 1960s and early 1970s, the FEM was applied to a
wide variety of engineering problems.

21. Computer-Aided Design

22. Computer-Aided Design

23. Computer-Aided Design