Prioritized Backup Power System

Transcription

1 Prioritized Backup Power System Texas Instruments Analog Design Contest Entry Prepared by John Kruckenberg, Andrew Lippolis, Eric Schacht, and Chris Seeley The Ohio State University

2 Executive Summary This document presents a prototype design of a residential backup power system for seamless transition among available backup power sources during residential power outages. The system provides a standard way to interface with many different types of power sources so they can be used appropriately when needed. In addition to the backup power transition, the system also relays power usage information to a computer that has been wirelessly connected to receive the usage data. The system works in real homes with the rated capacity of power circuits while complying with electrical safety standards. Introduction Society is becoming increasingly more dependent on electrical power, but concern about the pollution from wasted energy is growing. Due to the current demand for energy management devices and the simultaneous need to provide backup energy in the event of a power outage, a prioritized backup system could allow modern and future energy sources to interface adaptively with current and future residential electrical systems. Design The design of the prioritized backup power system was broken up into several categories and the team followed a strict design model to ensure a structured and realizable finished product. The overall system design consisted of hardware and software subsections to minimize system complexity, and to allow for a more modular design approach. This approach led to better distribution of human resources and also allowed for more system modularity, which allowed for better troubleshooting and upgradable components. Testing and Validation The system was simulated in MATLAB/Simulink in order to test the various conditions that the system would encounter during normal operation. Simulink s graphical nature allowed for rapid prototyping using hardware models for the system. The simulation environment helped identify potential system issues before the physical system was constructed. The system met all of the performance, reliability and safety requirements that were constituted in the original system framework. Design Review Many concerns and issues were discovered during the design and construction process. Noise issues, the interaction of high and low voltage circuits, and the non-trivial nature of measuring the power of reactive loads presented considerable design challenges for the group. A new system would include several changes that would reduce signal noise, decrease power consumption, and isolate high and low voltage equipment to maintain reliability, robustness, and safety. The dynamic nature of the prioritized backup power system necessitated many independent electronic components. Texas Instruments provided a powerful selection of well-engineered, robust, and easy to use components that allowed for the construction of a remarkable and reliable system. Prioritized Backup Power System i

3 Table of Contents Executive Summary... i List of Figures... iii 1. Introduction Purpose Relevance Problem Statement Scope Design Design Process Model System Requirements System Design Hardware Design Software Design Testing and Validation Software Simulation Hardware in the Loop System Calibration Validation of System Design Performance Reliability Safety Design Review Commentary on TI Products TI Component Selection Review Design Features that Should Change Design Features that Should Not Change Further Applications Prioritized Backup Power System ii

4 List of Figures Figure 1: Distribution of Residential Energy Usage in the United States... 1 Figure 2: V Model for Verification and Validation... 3 Figure 3: Subsystem Communication... 4 Figure 4: Overall Design Flow Diagram... 5 Figure 5: Completed System and Locations of Components... 6 Figure 6: TI Low Side Driver Relay Switching Circuit... 7 Figure 7: Primary Load Monitoring and Control Circuit Board... 8 Figure 8: Op-Amp Rectifying and Filtering Circuit... 9 Figure 9: System Simulation Model Top Level Figure 10: Circuit Breaker Box Subsystem Model Figure 11: Controller Subsystem Model Figure 12: Simulation Data Showing Chattering from Controller Figure 13: Simulation Data Showing Delayed Switch Condition to Prevent Chatter Figure 14: Hardware in the Loop Testing Figure 15: Calibration Curve for Resistive Loads Figure 16: LM317 Regulator Figure 17: UCC37324 MOSFET drivers Figure 18: ez430-rf2500 Wireless Development Tool Figure 19: OPA2344 Op-Amp Prioritized Backup Power System iii

5 1. Introduction 1.1 Purpose The purpose of the Prioritized Backup Power System is to distribute a limited supply of energy to the most important circuits at the expense of the least important ones. In order to do so, a priority must be assigned to each circuit by the user. This document presents a prototype design for assigning priorities to circuits while seamlessly transitioning among available power sources in the case of power shortages. Power shortages can occur if power from the electrical grid is not available and a backup source is used. The same concept can be used to encourage reductions of energy use. We built a system based on three principles of success in energy management that we have observed: 1. Consumers will buy more efficient products if they are priced reasonably 2. Consumers will use less energy if they get feedback and learn how to reduce consumption 3. Energy management is successful when features of the system are increased rather than limited 1.2 Relevance Society is becoming increasingly more dependent on electrical power, but concern about the pollution from wasted energy is growing. New growing technologies such as green energy generation, smart power grids, and alternative energy vehicles are beginning to find their ways into the homes of consumers, which presents opportunities to use these new technologies along with existing ones to provide the convenience of backup electrical power when it could not otherwise be available. It is notable that the power consumption of home loads may not be related to its importance in a power outage. For many consumers, powering the refrigerator, freezer, and communication mediums such as the telephone and internet devices may be very important, while the air conditioning, plasma TV, and water heating are less important. Automatically powering only necessary devices allows a home to run longer with a backup power source, or even use a backup source that is not powerful enough to run the entire house. Figure 1: Distribution of Residential Energy Usage in the United States Prioritized Backup Power System Page 1

6 New technologies are becoming commercially available, offering opportunities to provide backup power to a residence through an intelligent distribution box. While the following technologies are not typically used to provide backup power, the priority backup design can make use of the potential they offer: 1. Electric vehicles 2. Engine-powered vehicles 3. Solar power 4. Wind power 5. Sterling engines 6. Portable generators 7. High capacity battery backup systems Existing technologies are growing around the market of home energy management, but there are significant differences and advances in our design that are not seen elsewhere. Existing systems are all device-oriented. Systems like the X-10 hardware and Google Smarter Power allow monitoring or switching of individual components, but this process is remarkably tedious and difficult to troubleshoot. The priority backup system is centralized for ease of use and simple, reliable operation. Due to the current demand for energy management devices and the simultaneous need to provide backup energy in the event of a power outage, this design could be the solution that meets customers needs. The ability to meet multiple consumer needs makes this product a relevant one for today s society and culture. 1.3 Problem Statement Power outages are inconvenient and expensive, especially in modern society. However, extensive electrical outages are still occurring in recent years and in developed cities despite an over-developed sense of security that people may have. Examples of extensive power outages in Columbus, OH in recent years are the week-long outage due to Hurricane Ike in autumn 2008 and the Northeast Blackout in Power outages are disastrous and difficult to mitigate without very expensive backup power systems. 1.4 Scope The proposal is limited to a prioritized backup system and its common protocol for power and energy. The system is implemented as an information-based circuit switching system and a wireless interface to an automobile. While proposed as possible, the system does not include generating backup power or managing power use other than switching entire house circuits on or off based on optimization criteria. The proposal does not include managing other potential power sources such as solar cells. Prioritized Backup Power System Page 2

7 2. Design 2.1 Design Process Model In order to follow a consistent design process through the design and testing stages of development, the Prioritized Backup Power team followed the V-model. Advantages of this model include collaboration among team members, mbers, a reduction of project risks, and assured validation of design goals. A diagram representing the steps of the V model is shown below in Figure 2. Figure 2: V Model for Verification and Validation The steps of the V-model are described below: SYSTEM REQUIREMENTS The necessary specifications of the designed system are determined and a plan to test these requirements is written for future validation. SYSTEM DESIGN The high-level design is determined without considering low-level level subsystem details. DETAILED HARDWARE DESIGN Hardware is designed in detail such that it can be constructed. DETAILED SOFTWARE DESIGN Software is designed in detail so that it is ready for implementation. IMPLEMENTATION The hardware and software are combined in a working system for validation. SOFTWARE SIMULATION Software is tested in computer simulation in order to validate functionality of basic logical functions. HARDWARE in the LOOP Hardware is added to the controller simulation with some functions still emulated in software. SYSTEM CALIBRATION Using actual hardware, sensor readings are calibrated such that measured values are correct for accurate use. SYSTEM VALIDATION Entire calibrated system is tested to ensure that system requirements are met. Prioritized Backup Power System Page 3

8 2.2 System Requirements As a solution to the problem statement, technical specifications have been determined to be requirements for the system design. These include performance, reliability and safety considerations. 2.3 System Design The prioritized backup power system detects power loss, engages a backup power circuit, and manages the power used. To produce the system, an MSP430, a standard breaker box, a set of power relays, current sensors, and a voltage sensor were used. Communication between various backup sources, the residential circuit breaker box, and a user s PC occurs as described below. Backup Power Sources Home Electrical Loads PC User Interface Figure 3: Subsystem Communication The MSP430 series of microcontrollers meets the demand for: a high number of I/O channels, built in LCD drivers, high frequency sampling, and an on-chip comparator. The system monitors system voltage and currents on sources and circuits. The controller then reacts to power loss by disconnecting the grid and connecting and/or enabling available backup power sources. In addition to automatically connecting the backup source, the controller monitors and switches load circuits to maintain functionality for important loads while using a power-limited or capacity-limited backup source. Prioritized Backup Power System Page 4

9 Figure 4: Overall Design Flow Diagram After switching the system to operate on a backup power source, the system must determine which, if any, circuits need to be turned off to avoid overloading the backup source. The system defaults all circuits to the off state and turns the backup source on when the grid power is lost. When the source is available it iteratively adds the circuits according to available power and energy. The process of using the backup source and turning prioritized circuits on and off is summarized in Figure 4 which shows the flow diagram for load changing. Prioritized Backup Power System Page 5

10 The total system constructed includes three circuit boards to house all the hardware for monitoring and controlling the system. To power the control system, two power supplies for 120 volts AC to 12 volts DC connect to each AC source separately aand nd the 12 volts is connected in parallel to the primary circuit board. The grid power is switched by a large external relay shown in the breaker box. The backup source relay is integrated into the main control and monitoring board allowing for a very compact c design. Figure 5:: Completed System and Locations of Components 2.4 Hardware Design The load switching of the power system is very important to overall functionality. The hardware must be quick, robust,, and compact. For these reasons, TI low side drivers were used to switch mechanical relays that would in turn, switch the AC loads directly. This design allows complete isolation electrically for the Prioritized Backup Power System Page 6

11 microcontroller as well as robust operation. The large current carrying capability of the low side drivers enables them to drive the coils of mechanical relays using an extremely small signal from the microcontroller. The low side driver s wide range of output current at 12 volts allows a very versatile system stem driving anything from the grid s 100A relay to the load s 15A relays. Figure 6 shows a small portion of the main control board where the low side drivers are used to control two load relays. Figure 6: TI Low Side Driver Relay Switching Circuit In order to power the correct number of circuits, each individual circuit needs to be monitored constantly. Even when the system is still running on grid power, the circuits need to be monitored in order to maintain average power consumption information. The average power consumption information will be a key factor in determining when specific priority ity circuits need to be switched off to maintain backup power. Storage of power consumption information is dependent on how much system memory is available on the microcontroller. It may also be beneficial to keep several averages for each circuit. For instance, a separate average for the past minute, 10 minutes and hour may provide for better priority switching information. Along with gathering continuous power draw information about individual circuits, the monitoring system will also gather transient power draw data from each circuit. In backup mode the priority backup Prioritized Backup Power System Page 7

12 system will not be connected to the main power grid. Since the backup source may not instantaneously turn on, transient power draw information would be a valuable resource for maintaining system stability in switching events or startup. The transient data also provides a safety measure for the management of startup currents in the circuit. When devices are turned on, their transient power draw is generally much greater than the continuous load on the circuit. Therefore, storing and maintaining data from peak consumption is crucial to the management of the system. The constructed monitor circuit includes a voltage measurement of both the grid voltage and the backup voltage as well as a current measurement for each load. Using this monitoring the system has a measurement of the voltage on either the grid source or the backup source and then according to which source is connected to the system the power for each circuit and the entire system is calculated. The voltage is measured using two transformers that scale the voltages of the sources to 5 volts and then uses a high resistance voltage divider to scale the 5 volts to 2.5 volts. The current of each load is measured by a Parallex current transformer (sensor). Figure 7 shows the primary circuit board holding the microcontroller, control relays, low side drivers, current transformers, and microcontroller power supply capacitors and voltage regulator. Figure 8 shows the schematic for the signal conditioning of voltage and current measurements. This circuit uses op-amp circuits to rectify the AC signals and then low pass filter the signals. An additional circuit board was constructed to hold signal conditioning circuitry before connecting the signals to the analog inputs of the MSP430 microcontroller. Figure 7: Primary Load Monitoring and Control Circuit Board Prioritized Backup Power System Page 8

13 Figure 8: Op-Amp Rectifying and Filtering Circuit Beyond monitoring the power consumption at the breaker box, the backup source also needs to be monitored. In order to shut off certain prioritized circuits at correct intervals, the backup source needs to be polled for available power and energy. The remaining fuel or state of charge needs to be measured on the backup sources in order to give the priority backup system adequate sustainability information. The expected run time of the backup source will depend on the remaining fuel or state of charge and also by fluctuations in fuel or discharge efficiency. Since there are numerous devices that could be used as backup sources, power meters with built in wireless capabilities would have to be created for all unique systems. Hybrid cars usually supply the necessary information needed for monitoring, while other sources, such as gas generators, would need to be retrofitted with a tank measuring device that had built in wireless capabilities. The source power supply is a valuable resource in detecting faults in the backup system. For instance, if the total sum of the power being consumed by the individual priority circuits deviates from the power being supplied by the backup source, the user will be notified that there is a system malfunction that needs to be corrected. The priority backup system maintains the following rules in order to keep the highest priority circuits powered. 1. If a higher priority circuit consumes more power than the backup source can handle, then allow lower priority circuits that do not consume more power to operate. 2. Allow highest priority circuits to remain on while the backup source can maintain them. As the backup source is unable to provide enough power for lower priority circuits, then shut them off. 3. When the backup source is switched on, keep all circuits off. Decide which priority circuits can be turned on. Turn on the highest transient producing circuit first, and then sequentially turn on the next highest transient producing circuit until all maintainable priority circuits are on. 2.5 Software Design In order to design several subsystems quickly and efficiently, the team chose to use multiple TI ez430- RF2500 microcontrollers. The use of multiple microcontrollers allowed the division of work among Prioritized Backup Power System Page 9

14 multiple team members. This approach was very practical due to the clear divisions among identifiable projects and due to the low cost and feasibility of purchasing multiple ez430 kits for development. Examples of divided tasks are: Wireless communication Serial communication Analog interpretation of sensor data Control logic Digital output switching These projects were divided and solved individually before being combined into a single system for development. To begin the process, the first MSP430 was connected to a computer that ran a simple priority switching program. The program sent serial data to the first microcontroller, which in turn transmitted this data wirelessly to the second microcontroller in the breaker box. The data sent was a simple string of characters that was then degenerated into single characters on the micro inside the breaker box. These characters would be used as priority switching information. The data included remaining battery power, and which priority each breaker in the box was. This way, intelligent switching algorithms could be implemented to turn off certain breakers depending on the backup and priority information. Not only did the IAR-Kickstart application provide rapid development and debugging solutions, it was easy to use and the cost was included in the purchase of the microcontroller. It would be hard to find another solution that contained the same level of ease, low cost, and flexibility that the MSP430 provided. The IAR programming suite made it easy to jump in and start coding for the MSP430. Even though none of the group members had much experience programming a microcontroller before the project, the flexibility of being able to code in assembly, C, or C++, contributed greatly in the ability to rapidly develop and modify the functions of the microcontroller in the breaker system. Another nice feature in the IAR software was the debug mode. Since it was easy to execute code until a certain line and also check values of variables mid execution, it was much easier to find errors and correct coding issues. 3. Testing and Validation 3.1 Software Simulation Software simulation was done in MATLAB/Simulink to offer an environment where various conditions and control could be tested quickly. The software being designed in Simulink provided the first layout of the system due to the graphical nature of Simulink. In addition, the system theory of operating various loads on an automatic basis was tested with a simplified controller. The Simulink model created showed all aspects of the system in a visual environment. Figure 9 shows the model from the top level. Beneath the surface of each sub-system the components are modeled. The breaker box sub-system is shown in Figure 10 and the controller is shown in Figure 11. Prioritized Backup Power System Page 10

15 Figure 9: System Simulation Model Top Level Figure 10: Circuit Breaker Box Subsystem Model Prioritized Backup Power System Page 11

16 Figure 11: Controller Subsystem Model In order to increase software modeling speed the model was created only with basic load dynamics and a simple conceptual state flow controller. This simplification allowed a very rapid calculation speed, with minimal error. The software environment helped identify chattering issues in development and final software could then be written to prevent chattering. Figure 12 shows the chattering seen before adding a delay after the switching process. Figure 13 shows after the chattering was removed with software modifications. Prioritized Backup Power System Page 12

17 Figure 12: Simulation Data Showing Chattering from Controller Prioritized Backup Power System Page 13

18 Figure 13: Simulation Data Showing Delayed Switch Condition to Prevent Chatter Prioritized Backup Power System Page 14

19 3.2 Hardware in the Loop The most expensive component of our backup power system would be the backup power source. In order to test the system s functionality when operating with a backup storage system or alternate energy source, tests were performed in the form of Hardware in the Loop. This strategy allowed the team to test our existing software with our control system while simulating hardware that is not yet available. The three test modes for the system s Hardware in the Loop operation were: 1. Simulated depleting energy source 2. Alternate energy source, non-depleting 3. Alternate energy source with intermittent availability (user-generated) Figure 14 shows the power measurement (in ADC bits, not calibrated) of the four load circuits as the user-generated power availability changes. This test demonstrates the functionality of the system. The system is turning individual loads on and off by priority, so the measured load power is fluctuating. Figure 14: Hardware in the Loop Testing 3.3 System Calibration In order to interpret the power consumption of the four load circuits, the ADC output codes need to be converted to power consumption in watts. This was done by comparing the ADC data to a Kill A Watt Prioritized Backup Power System Page 15

20 power meter. The calibration curve for several resistive loads is shown below. As expected, the transfer curve is quite linear. After the calibration data was taken, the conversion formula was used in the data acquisition program in order to display the power consumption information in watts. Power measurement (Watts) Calibration curve for power measurement y = -5E-05x x R² = Analog input value (ADC bits) Figure 15: Calibration Curve for Resistive Loads 3.4 Validation of System Design The system was proven to meet the system requirements of performance, reliability and safety considerations. Performance goals were met for switching to backup power, turning off loads according to power availability and priority, and recording and displaying data. In addition, the system was packaged in a reliable and safe package as shown below Performance The system measured and controlled loads based on original design. The system had limitations measurements, which limits further testing and performance as explained further in the Lessons Learned section Reliability The constructed system performed the same results with various loads. The system continued to perform without failure throughout testing aside from hand construction requiring initial troubleshooting to diagnose loose or faulty connections. The system reliability could be improved as explained in the Lessons Learned section. Prioritized Backup Power System Page 16

21 3.4.3 Safety The system was capable of maintaining all original circuit protection in the form of panel box breakers. In addition the system was capable of housing the properly sized components and wiring to safely and efficiently perform the design functions. 4. Design Review The system constructed performed well in a prototype setting. Selected components served reliably in functionality and versatility. However, during the design and construction process many aspects of the design were revisited and further changes would be made for a new system. It was known prior to construction that signal noise is a risk or concern. In addition, household voltage next to low power electronics poses a danger to both the components and the assembly of the system due to the large potential difference. The risks prove real in noise primarily, but were never experienced for household power next to low power. Another considerable concern seen in two parts relates to the current measuring. Converting an AC current measurement to a DC voltage signal is not trivial. The two parts proving difficult were rectifying the signal and measuring the power factor. Rectifying the signal was accomplished with reliable accuracy, but had a very small range of measurement. The second part proving difficult was the power factor or real versus imaginary loads on the system. Measuring power factor accurately on the system is important to final accuracy, but would require more hardware and more processing then currently implemented. A much less concerning, but further understood fact of the system relates to hardware and circuitry construction. In keeping the scope of the project within well achievable goals a totally integrated system was never considered, but was understood to usually prove most accurate, reliable, and easily manufactured. The modular approach chosen allowed the team to function independently and the system boards and components to be removed and tested separately. The space freedom also allowed reliable construction under this simple proof of concept system and modular approach. However, the separation of components and wiring involved introduces noise and additional connections to troubleshoot. Any new system built would begin to integrate the components together on smaller boards and with greater precision. This would move towards a more manufacturable design with less signal noise, power consumption and greater reliability. Lastly a considerable amount of effort would be made in further design to keep household power from the low power electronics, even in an integrated system. 4.1 Commentary on TI Products The use of TI parts during the design and implementation of the project had advantages and disadvantages. A major advantage of using the TI ez430-rf2500 was the ease of plug and play with Windows XP and Windows 7 RC1. The software and hardware were so easy to use that it only took 15 minutes to get a sample demo running on the controller with a good representation of its functions. The EZ430 microcontrollers have a large amount of potential to make rapid prototyping projects possible, but there are some features that should be adopted to make their use easier. The incompatibility of the software on Windows Vista was a prohibitive problem among the team members. Having a group of demonstration programs to use with the microcontroller was very useful in creating the code for the microcontrollers in the priority circuit box. However, more commenting of the distributed code would have been helpful. Development would be much more appealing with walkthrough programs to clarify Prioritized Backup Power System Page 17

22 the code s functions 1. To quickly gather information, it is important to have a streamlined support site with easy access to information. As more information is available, this interface should be improved to reduce clutter. While the IAR workbench software provided the necessary functions, additional features would reduce development time and organization: Standard libraries for tasks such as converting strings to integers and sleeping Saving versions of the workspace with different names for improved version tracking Autocomplete of function names and argument lists Hardware support from TI was fantastic. Free samples from TI were a great resource in the completion of the project. The rapid delivery time and wide selection of samples allowed for the proper component selection in the sub-circuits. The datasheets for the samples were easy to access from the web and included all the necessary information for using the components. 4.2 TI Component Selection Review The prioritized backup power system consists of power, switching, control, and analog sensor processing systems. These functions rely heavily on selecting the best components, and Texas Instruments provided the well-engineered components we needed for rapid prototyping of the powerful and reliable system. Reliable and safe power: Adjustable voltage regulator (TI LM317) The LM317 adjustable voltage regulator provides a simple and versatile power source over a wide range of 1.25 to 37 V outputs. Built-in safety and reliability features of this component were vital to the system s success: Ease of use for rapid prototyping designs Internal short circuit current limiting and thermal overload protection 0.01 % load regulation per volt, 0.1 % line regulation per volt Figure 16: LM317 Regulator Load switching: Power MOSFET Drivers (TI UCC37324P) To amplify logic level signals for high-power operations such as switching large relays and contactors, we chose TI low-side power MOSFET drivers. The TI chips had features that fit the load switching applications perfectly: Figure 17: UCC37324 MOSFET drivers High power, very versatile chips in a development-friendly package Fast ns switching time Low power, low heat dissipation 1 Example Learning section reduces the learning curve for programming the device: Prioritized Backup Power System Page 18

23 Control supervisor: Wireless Development Tool (TI ez430-rf2500) The prioritized backup power system requires a powerful supervisory controller with access to analog, digital, serial, and wireless interfaces. In addition, the controller must be easy to access, program, and debug in order to aid rapid prototype development. Critical ez430vfeatures are: Simple USB programming and debugging interface Built-in CC GHz wireless adapter for safe and reliable use with high voltage power distribution box Fast 16-MIPS performance Ultra-low power consumption, stays alive with capacitor charge Figure 18: ez430-rf2500 Wireless Development Tool Analog sensor processing: Rail-To-Rail Operational Amplifier (TI OPA2344) Oscillating signal measurements and complex power calculations are best made real-time using analog op-amp designs. The OPA2344 excels due to: Figure 19: OPA2344 Op-Amp Rail-to-rail input and output, very significant in logic level signals Low power usage, as with the ez430 controller Compact, easy to use package: 2 op-amps on 8-DIP component. 4.3 Design Features that Should Change The system that was built is for proof of concept therefore further design or implementation of the system includes many changes or upgrades. These changes include expansion, better accuracy, better reliability, and more measurement. The following changes would be made in future work: 1. Add many more communicating devices. For example the backup source needs to communicate information that is currently user input, such as power and energy available. 2. Shield and encase the sensors and analog signal wires to prevent signal noise. 3. Design system around production type components such as surface mount board and chips to greatly improve robustness, reliability, and construction of the circuitry. 4. Reduce power consumption of additional circuitry used to operate the system such as using normally closed relays so that during normal grid operation there is a minimal power loss. 5. Add separate location for main and backup source breakers to distinguish source protection from load protection devices. This would result in clarity for installer, technician, and user. 4.4 Design Features that Should Not Change The system shows exemplary performance in a prototype environment, therefore many original system design aspects would not change. The following aspects would not change in future work: Prioritized Backup Power System Page 19

24 1. The TI MSP430 provides a versatile low power microcontroller; this would not change as it best meets the system needs. However, larger systems would require a different model with more I/O and additional memory. 2. The TI low side drivers carry the current for operating devices operated by the controller, therefore these would remain the same. 3. Current measurements would remain transformer based sensors, which prevents heating of the element changing calibration under loads. 4. The system would still be implemented inside or at the main breaker box of an electrical system. This proves to be the best place to centralize and control such as versatile system for power outage control and home automation. 4.5 Further Applications The original concept of a backup power system, which prioritizes and controls the loads allows for many further ideas and concepts to be explored. The team discussed many different features that could add on to the backup system or operate from the designed hardware. The following applications or additions to the system were considered: 1. Automating the home could be implemented. This could provide light changing during vacation, and shut off non-essential rooms or loads at night, etc. This addition would simply require computer software on the remote access for setting the priority. 2. The system could provide remote access to home power. This would require a new system and software that would communicate with the breaker box controller. 3. Adding frequency and source syncing could allow alternative energies such as wind, solar, and batteries to be controlled and used by the system. 4. The system could provide security for the home by implementing new sensors that would turn loads on and off based on sensing around the home. Prioritized Backup Power System Page 20