1© 2015 The MathWorks, Inc.

Modeling and Simulation of Electromechanical

Systems

Dhirendra Singh

dhirendra.singh@mathworks.in Vivek Raju

Application Engineer Application Engineer

2

Challenges

Working with Multi-Domain systems (Mechanical, Electrical)

Modeling Kinematics & Mechanisms of Mechanical design

Determine the sizing of the electrical components like motors and optimize the parameters

Develop appropriate control logic (Field oriented control and event based control logic)

Perform real-time simulation for rapid control prototyping and hardware-in-the-loop simulation

3

Demo

Electrically Assisted Power Steering

4

Challenge 1:

Working with Multi-Domain systems (Mechanical,

Electrical)

To address this challenge

We need to have a platform which allows working with Electrical, Mechanical

and Control system in a single environment

5

Introduction to Simscape

Enables physical modeling (acausal)

of multidomain physical systems

Eases process of

modeling physical systems

– Build models that reflect

structure of physical system

– Leverage MATLAB to create

reusable models

Used by system and control

engineers to build models

with the same structure

as the physical system

V+

V-

6

Develop Complex Multidomain Systems

Physical

Hardware

S1

S2S3

Software &

Algorithms

A B

P TT

PID+-

if (..)

x = …

else

x =

Inputs and outputs

Software components

Physical connections

Simultaneous equations

Use the right language for the right task

Use Model-Based Design on the entire system

7

Challenge 2:

Modeling Kinematics & Mechanisms of Mechanical

design

To address this challenge

We need to have platform to model kinematics and mechanisms of mechanical

systems and simulate the dynamics.

We also require to import existing enterprise CAD models.

8

Modeling Kinematics & Mechanisms of Mechanical design

Enables multibody simulation

of 3D mechanical systems

Construct model using

bodies, joints, and forces

– Model matches structure of system

– No need to derive and program equations

Primary uses

– System-level analysis of

mechanical and multidomain systems

– Control development in Simulink

9

Modeling Mechanical Systems

Foundation library of basic

mechanical components

– Mass, spring, damper

– Friction

– Translational or rotational

– Mechanisms (gear, rack-pinion)

Combine components to create

reusable systems

Combine with Simscape Driveline

and Simscape Multibody

to model more complex systems

10

Working with

Simscape Multibody

Build components

– Predefined solids

– Extrusions defined in MATLAB

Parameterize components

– MATLAB variables

– Custom dialog boxes

Connect with joints

– Sense and actuate

– Guide assembly

11

CAD to MATLAB

to Simscape Multibody

1. Export from CAD to MATLAB code

– SolidWorks:

CAD2MATLAB_SolidWorks.swp

– Other CAD System: Adapt code

to your CAD system’s API

2. Run MATLAB code to create

data structure in MATLAB

3. Run data2smixml.m to generate

Simscape Multibody XML file

4. Import Simscape Multibody XML file

to create Simscape Multibody model

parameterized with STL files

for animation.

CAD

robot.m

smiModel

robot.xml

robot.slx

>> robot.m

>> smimport(‘robot.xml’)

2

4

part.STL

CAD2MATLAB_SolidWorks.swp

3

1

>> data2smixml(smiModel,’robot.xml’)

12

Key Takeways

Provides libraries for modeling

3D mechanical systems

Use 3D visualization to animate

simulation results and explore model

Connect to other physical domains

and controller in a single environment

13

Challenges

Working with Multi-Domain systems (Mechanical, Electrical)

Modeling Kinematics & Mechanisms of Mechanical design

Determine the sizing of the electrical components like motors and optimize the parameters

Develop appropriate control logic (Field oriented control and event based control logic)

Perform real-time simulation for rapid control prototyping and hardware-in-the-loop simulation

14

Challenge 3:

Determine the sizing of the electrical components like

motors and optimize the parameters

To address this challenge

We need to model the motor, analyze the behavior by simulating the model and

optimize the parameters of the electromechanical system.

15

Model and Simulate DC Electromechanical System.

Problem: Model a DC motor with

a configurable PWM controller

in the Simulink environment

Solution: Use Simscape Electronics

to model the mechatronic system

Model:

DC Motor

Motor

Servoamplifier

+-

16

Modeling 3-Phase Electrical Systems

Problem: Build a modular,

intuitive model of a 3-phase

electric motor without deriving

equations.

Solution: Use Simscape Power

Systems to model the System.

Model:

a

b

c

17

Estimating Model Parameters of Motor

R L J K B

3 0.01 0.01 0.02 0.5

Problem: Simulation data does not

match measured data because the

parameters are incorrect

Solution: Use Simulink Design

Optimization to automatically tune

model parameters

Model:

+- 12V

Up

Up Down

Down

V+V-

R = Resistance

L = Inductance

J = Inertia

B = Friction

K = Back EMF Constant

R L J K B

4.03 1e-4 0.11 0.45 1.07

18

Challenge 4:

Develop appropriate control logic (Field oriented

control and event based control logic)

To address this challenge

We need to tune the proportional and integral values to an

appropriate level for a smooth steering control.

19

Optimize System-Level Performance

and Meet Design Requirements

Simulating plant and controller in one environment allows you to optimize

system-level performance

Plant

+u y

Controller

s1 s2

s3

20

Demo: Field Oriented Control of PMSM

3-Phase

Inverter

PMSM

Motor

Va Vb Vc

Space

Vector

PWM

Position & Speed

Sensing

PIInv_Park

Transform

d,q

To

alpha,beta

Clark

Transform

a,b,c

to

alpha, beta

Ia

Ib

Park

Transform

alpha, beta

to

d, q

Is_alpha

Is_beta

Vs_alpha

Vs_beta

PI

PI

Vsq_ref

Vsd_refIsd_ref

_

_

+Isq_ref

Is_d

Is_q

Desired

RPM

_

RPM

theta

21

Challenge 5:

Perform real-time simulation for rapid control prototyping and

hardware-in-the-loop simulation

To address this challenge

We need to have a real-time operating system to quickly prototype the control

system before implementing in an embedded processor and also perform an

hardware-in-the-loop simulation.

22

Simulink Real-Time Enables Real-Time

Simulation and Testing

Rapidly create real-time applications from Simulink

models and run and test them with your hardware under

test at normal operating frequencies, speeds, and timing. Metso was able to

achieve multiple goals

simultaneously. They

were able to developed a

sophisticated controller

for digital hydraulics that

is more reliable, accurate,

and efficient than

previous systems, and

they were able to

accelerate their

development.

“Simulations in Simulink

and real-time testing with

Simulink Real-time

helped us deliver an

exceptionally reliable

control system.”

Kari Leminen, Metso

23

I/O Output I/O InputI/O Output I/O Input

Real-Time Simulation and Testing Tasks: Rapid Control Prototyping

Physical Plant Hardware

Wiring and

Signal Conditioning

0

0

Target Computer Hardware

24

Wiring and

Signal Conditioning

Embedded Controller HardwareTarget Computer Hardware

Real-Time Simulation and Testing Tasks: Hardware-in-the-loop (HIL) Simulation