EE361-Electromechanical Energy Conversion

class: center, middle

# EE-361
# Speed Control of DC Motors

## Ozan Keysan

[ozan.keysan.me](http://ozan.keysan.me)

Office: C-113 <span class="meta">•</span> Tel: 210 7586

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# Motor = Generator

## No difference between a [DC motor and generator](http://www.youtube.com/watch?v=6kgzrXFSDwA)

## Richard Feynman in [Electric Motors](https://youtu.be/qhh32JYkQPk?t=23s)
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# DC-Machine Equations

- ## Induced Voltage Proportional to Speed
## \\(E\_a = K\_a \omega\_m \Phi\_{pp}\\)
--

- ## Torque Proportional to Armature Current
## \\(T =K\_a  \Phi\_{pp} I\_a \\)
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# DC-Machine Equations

- ### The direction of \\(I_a\\) is determined by the relation between \\(V_t \\) and \\(E_a \\)
--

- ### If \\(V_t > E_a \\) it's motoring mode.
--

- ### If \\(E_a > V_t \\) it's generating mode.
--

- ### The speed changes depending on the net torque and inertia

## \\(T\_{elec} - T\_{mech} = J \dfrac{d \omega}{dt}\\)
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# DC Machine Types
## Different ways to supply and control the field winding

### - Separately Excited (The most common type)
### - Shunt Excited
### - Series Excited
### - Compound Machines

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# DC Machine Types
## Different ways to supply and control the field winding

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# Series DC Motor
--

<img src="http://electriciantraining.tpub.com/14177/img/14177_44_1.jpg" alt="Drawing" style="width: 300px;"/>
## What happens if AC is applied?

### Series DC Motor = Universal Motor (Works both with AC and DC)
[How universal motors work?](http://woodgears.ca/motors/dc.html)

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# What is the origin of AC/DC band's name?

## [Highway to Hell](https://youtu.be/gEPmA3USJdI?t=89)

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<img src="images/ee361/singer.jpg" alt="Drawing" style="width: 800px;"/>

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# Steady State Operating Point
### Intersection of motor characteristics and load curve (\\(T\_{elec}=T\_{mech}\\))

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# Separately Excited Motor

## What happens if the field current is increased in a motoring mode?

## What happens if we swap the field winding terminals?

-->
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# Four Quadrant Operation

[Riding a robot hand](https://www.youtube.com/watch?v=IwE6VIPTcFg)
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# Generating (or Braking) Mode

## 1-Regenerative Braking

### Generated energy is sent to the source 
### Energy is not dissipated, so it is quite efficient way of braking
### Voltage source has to be bi-directional
### \\(I_f\\) can be controlled to adjust \\(E_a\\)

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## 1-Regenerative Braking Case study

## Formula-1 [Kinetic Energy Recovery System: KERS](https://en.wikipedia.org/wiki/Kinetic_energy_recovery_system)
<img src="./images/ee361/formula_kers.png" alt="Drawing" style="width: 800px;"/>

[Renault KERS](https://www.youtube.com/watch?v=w7hLY_U5OUE), [F1 Energy Recovery System](https://www.youtube.com/watch?v=vgBdlOgCmJU), [BBC KERS](https://www.youtube.com/watch?v=n9fAnjgR8lA),
[KERS explained](https://www.youtube.com/watch?v=k8lyBFmkAKw), [Power Unit Regulations](https://www.fia.com/sites/default/files/publication/file/FIA%20F1%20Power%20Unit%20leaflet.pdf)

[KERS specs](https://www.quora.com/What-is-KERS-and-how-it-is-used-in-Formula-One), [specs2](http://jalopnik.com/how-formula-ones-amazing-new-hybrid-turbo-engine-works-1506450399)

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## 2-Dynamic Braking

### Kinetic energy is dissipated using a braking resistor
### It is not very efficient
### Easy to implement (no need for bidirectional voltage source)

#### A braking resistor for elevators

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## 2-Dynamic Braking

### Kinetic energy is dissipated using a braking resistor

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## 2-Dynamic Braking

### Case Study: Locomotives

[Dynamic Brake Noise](https://www.youtube.com/watch?v=YGc8Y2KQ7-c), [Braking in Trains](https://www.youtube.com/watch?v=TX_QW6h1jH0)
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## 2-Dynamic Braking

### Case Study: Locomotives

[Dynamic Brake Noise](https://www.youtube.com/watch?v=YGc8Y2KQ7-c), [Braking in Trains](https://www.youtube.com/watch?v=TX_QW6h1jH0)

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## 3-Plugging

### Suddenly reverse the polarity of \\(V_t\\)

### Fastest way to stop the motoring

### Not suitable for continuous operation as all the kinetic energy is dissipated in the motor

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# Electric Braking

## 3-Plugging

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# Electric Braking

## 3-Plugging

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# Speed Control of DC Motors
### What are your options, if you want to change the operating point?
--

- ## Vary the terminal voltage (\\(V_t\\))
--

- ## Vary Field Current (\\(I_f\\)) (and hence flux)
--

- ## Vary Both

<!--
# Hybrid Car
## Toyota Prius

![](https://inhabitat.com/wp-content/blogs.dir/1/files/2011/01/PriusEngine.jpg)

# Hybrid Car
## Toyota Prius

![](http://l.yimg.com/us.yimg.com/i/us/aut/ph/gc/greencar_f32_img2.jpg)

## What happens if you drive uphill?
-->
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# Armature Voltage Control

--
- ## Speed control over a wide range
- ## Commonly used

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# Armature Voltage Control

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# Armature Voltage Control Techniques:

## How can you generate a variable voltage from a constant voltage source?
--

## Inefficient and unsuitable methods

- ### Voltage divider resistances
- ### BJT transistors

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# Armature Voltage Control Techniques:

## Pulse-Width Modulation (PWM)

![](https://circuitdigest.com/sites/default/files/inlineimages/DC%20motor%20control%20figure1.gif)
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# Armature Voltage Control Techniques:

## Pulse-Width Modulation (PWM)

![](http://ebldc.com/wp-content/uploads/2009/08/pwm_speed.jpg)

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## Pulse-Width Modulation (PWM)

## But you can't drive a motor like that. WHY?

![](https://circuitdigest.com/sites/default/files/inlineimages/DC%20motor%20control%20figure1.gif)

## Pulse-Width Modulation (PWM)

## Solution use a switch with a free-wheeling diode:

## Step Down (Buck) Converter

## Simplified Buck Converter

## Let's obtain voltage and current characteristics.

# Armature Voltage Control Techniques:

## Uni-directional Control

-->
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# Armature Voltage Control Techniques:

## [H-Bridge](http://www.modularcircuits.com/blog/articles/h-bridge-secrets/h-bridges-the-basics/) : Bi-directional Control

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# Field Current Control
--

- ## An external resistor or variable voltage supply
--

- ## Usually used to achieve higher speeds -->
--
Decrease \\(I_f\\) (Flux weakening)
--

- ## Speed control over a narrow range
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# Field Current Control

<img src="http://www.electrical4u.com/electrical/wp-content/uploads/2013/04/Field-Flux-Control-of-DC-Motor-9-3-15.gif" alt="Drawing" style="width: 800px;"/>
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## Operating Range of Electrical Machines

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## Operating Range: Audi E-tron

#### [The Electric Drivetrain with Three-motor Layout of the Audi E-tron S](https://link.springer.com/article/10.1007/s38313-020-0254-2)
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## Operating Range: Audi E-tron

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## Operating Range: Audi E-tron

#### [The Electric Drivetrain with Three-motor Layout of the Audi E-tron S](https://link.springer.com/article/10.1007/s38313-020-0254-2)
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## Operating Range: Audi E-tron

#### [The Electric Drivetrain with Three-motor Layout of the Audi E-tron S](https://link.springer.com/article/10.1007/s38313-020-0254-2)
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# Equivalent Circuit with Mechanical System

<img src="http://ctms.engin.umich.edu/CTMS/Content/MotorSpeed/System/Modeling/figures/motor.png" alt="Drawing" style="width: 500px;"/>
## Dynamic response limited by: Inertia & Inductance

[Fast robotic arm](https://youtu.be/SOESSCXGhFo?t=15s)
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# Equivalent Circuit with Mechanical System

[Integrated modeling and analysis of dynamics for electric vehicle powertrains](https://www.sciencedirect.com/science/article/pii/S0957417413008129)
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# Control Dynamics:
### What are the factors affecting dynamic precision?
--

- ### Inertia (or mechanical forces)
--

- ### Motor Inductance
--

- ### Measurement
--

- ### Processing
--

- ### Power Electronics

[Robot table tennis](http://www.youtube.com/watch?v=tIIJME8-au8), [Robot katana](http://www.youtube.com/watch?v=cR-YlZ9NdIA), [fast robot](https://www.youtube.com/watch?v=vN7BPyy69Ds)

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## You can download this presentation from: [keysan.me/ee361](http://keysan.me/ee361)

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# Electric Commutator
![](http://1.bp.blogspot.com/-13XK9MkbZHA/T6_omiWJm7I/AAAAAAAAB_c/A6GBqsp2700/s640/COMMUTATOR+EXAMPLE.JPG)

# Can you find a way to remove commutators?

## Brushless DC Motors
### Rotating Magnets, Stationary Coils

![](http://img.frbiz.com/pic/z1be797c-0x0-0/1050kv_11_1v_brushless_dc_strong_style_color_b82220_outrunner_strong_motor.jpg)![](http://www.ezcfn.com/images/dc_fan_fp_108_d_dc.jpg)

# Brushless DC Motors
### Rotating Magnets, Stationary Coils

[How brushless DC motors work?](http://www.youtube.com/watch?v=bCEiOnuODac)

# Brushless DC Motors
### Rotating Magnets, Stationary Coils

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