SED3: The Control System

This is a sub-section of my posts describing the Sustainable Energy Design 3 course group project to Design and Build a Micro Wind Turbine – for more information see here

Overall System

sed3_controlsystem_diagram
Figure 1 – Control System Diagram || Erin Nolan 2016 || pigeonsblue.com

The control system is designed to monitor variables across the overall system and feedback so as to improve and optimise the outputs. The potential system for the turbine is shown in Figure 1 with the outputs and inputs labelled on the arrows.

There are two main different methods of monitoring and providing feedback and that is through either:

  • hardware circuit design
  • programming software design

Although mechanical methods are also possible, the relevant methods are generally too inefficient for this application.

Hardware used to be the most popular method of control in micro wind due to the smaller costs of components than the cost of a microcontroller necessary to run software, however as microcontrollers have become more popular over recent years, their cost has dropped and so this comparison is less relevant. As software allows for greater control of variables, allows them to be communicated in more useful formats (such a text file to be read on a computer as opposed to an LED screen display) and ease of correction, we are going to use software for our overall control system.

Turbine

sed3_control1
Figure 2 || Erin Nolan 2016 || pigeonsblue.com

 

Generator

sed3_control2
Figure 3 || Erin Nolan 2016 || pigeonsblue.com

 

Rectifier

sed3_control3
Figure 4 || Erin Nolan 2016 || pigeonsblue.com

 

Microcontroller

sed3_control4
Figure 5 || Erin Nolan 2016 || pigeonsblue.com

Battery Management System

sed3_control5
Figure 6 || Erin Nolan 2016 || pigeonsblue.com

Maximum Power Point Tracking

sed3_control6
Figure 7 || Erin Nolan 2016 || pigeonsblue.com

Wind Speed Measurement

sed3_control7
Figure 8 || Erin Nolan 2016 || pigeonsblue.com

Choice of Microcontroller

There are a variety of microcontrollers available, including those that are specialised with code already pre-written and implemented for use in similar systems to ours but as these are considerably more expensive than a generic, programmable one, we have decided to not use them.

Raspberry Pi

The Raspberry Pi is not just a microcontroller, but a microcontroller and other units containing many unnecessary features and components not relevant to this application. It was originally designed not so much to enable efficient connectivity for projects like this but to be used more as an educational tool.

Arduinos

The most popular generic microcontrollers are Arduinos which, due to their popularity, have a lot of resources and support available to them. However, they come with the problem of communication as further modules are necessary to implement effective connectivity. This means increasing workload an/or costs.

The basic modules were being offered pre-paid for by the University and we suspect some of Stein’s own personal supply so they would come with the advantage of that cost removed. However there were a limited supply available to the course, and I had my own personal supply of different microcontrollers that could be used and thus negating that advantage somewhat.

ARM mBeds

These at the time of the project were less accessible in terms of ease of development, amount of support available, and costs, in addition to the communication problem of the Arduinos.

Particle Cores

Particle Core microcontrollers were still relatively new at the time of the project, with more limited support than Arduinos or Raspberry Pis. However they use a variant of the C/C++ based Wiring as Arduino but just normally developed within the online Particle Core IDE, so its ease and time for development would be comparable to the Arduino, allowing me to tap into the larger Arduino support.

Additionally they had faster read times for quicker response for control system which makes it more effective at minimising losses.

Finally, and most importantly, you could get either the WiFi enabled ‘Photon’ or the 3G enabled ‘Electron’ both allowing users to maintain internet connectivity in a practical, wireless form.

Particle Core Microcontroller

Therefore one of the two Particle Cores was chosen to be used. In the end, there was insufficient time left in the project to complete and test the control system and so the connectivity benefits were never trialled. I had not long received my Electron in the post from backing the Kickstarter campaign and so although the Photon may have been sufficient for demo purposes I developed on the Electron anyway and was rather gutted at never finishing.

The most important features of the microcontroller for our application:

  • 8 channels (A0 to A7)
  • 12-bit resolution
  • it will map input voltages between 0 and 3.3 volts into integer values between 0 and 4095
  • a resolution between readings of: 3.3 volts / 4096 units or, 0.0008 volts (0.8 mV) per unit.
  • one AC-DC converter – every analogRead() has to be run serially through that one converter because that makes the fast read/write time periodic for each function, so the more readings I take, the less frequently each reading is taken.
photon-jtag
Figure 9 – Pinout Diagram for the Particle Photon Microprocesor

Next: Battery Management System

This is a sub-section of my posts describing the Sustainable Energy Design 3 course group project to Design and Build a Micro Wind Turbine – for more information see here

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s