辅导案例-ENGN4625

  • May 15, 2020

ENGN4625 & ENGN6625Power Systems and Power ElectronicsDesign AssignmentPower Supply Design1 Assignment DeliverableA well-formatted and laid out report containing details of your power supply design, withjustifications for decisions made, and validated test results including analysis of outputreliability and impacts on power quality.Maximum of 10 pages, including design calculations, figures, tables, key schematicsand waveform images. Additional waveform images may be included in an appendix andcommented on in the main body of the report.More details on project report expectations can be found in Section 6.2 OverviewYou work for a consumer electronics design company that is developing a Smart-deviceDocking Station capable of providing power to a range of smart devices (phones, tablets,music players, etc), audio amplifiers, as well as providing an auxiliary power supply. Thedocking station is required to be able to plug into any single-phase power outlet anywherein the world, and should be compliant to applicable power quality standards. Your role atthe company is to design and test a power supply system that is capable of supplying thevarious parts of the docking station with the necessary quantities of power at the requiredvoltages. The requirements are detailed in Section 3.There are four main parts to the project which you should complete: Converter Design,Stage 1 Converter Build and Test, Stage 2 Converter Build and Test, and then finallycombining the two converter stages together into one Complete Power Supply Circuit andtesting.3 Power Supply SpecificationsThe basic power supply system and requirements are represented by the block diagramshown in Figure 1. You are required to use a standard diode bridge rectifier, and thendesign two separate DC-DC Converters (Stage 1 shown in green, Stage 2 in red in theblock diagram). Your company requires that the second (red) DC-DC Converter thatyou design be flexible enough such that a single design can be manufactured which sat-isfies both separate end-use voltage and power requirements. The Stage 2 convertershould be able to be powered via the mains/Stage 1 Converter. In order to help re-duce manufacturing costs and to keep the product as lightweight as possible, you should1design all converters to operate at a switching frequency of at least fsw kHz wherefsw = (30 +∑(your numeric UNI− ID numbers)) kHz 1, and avoid using excessivelylarge components. It makes sure that there isn’t a single solution for the design. So it isnot like doing an assignment with a fixed solution (like early year AQF Level 7 work). Itis closer to a real-world design requirement. Everyone will end up with a different design.Figure 1: Power supply block diagram.4 Project RequirementsPart 1 – Converter DesignRectifier/Stage 1 DC-DC Converter: Start by designing the Rectifier and Stage 1 DC-DCconverter. Unlike the rectifiers mostly discussed in the notes, you won’t have a large enoughload to enable inductive filtering on its own to smooth the output (without using a verylarge inductor). And like the hardware labs, if you use too large a capacitive filter it willresult in large amount of harmonic distortion on the input side. You should instead allowthe rectifier output to have some capacitive filtering but still fluctuate over a reasonablerange, and rely upon the Stage 1 DC-DC converter to provide suitable regulation and aconstant 36 V output.Stage 2 DC-DC Converter: You need to come up with a single converter design thatwill work for both loads. The converter should be operated at least fsw kHz, although itdoes not have to be the same switching frequency as the stage 1 rectifier.1For example if your UNI-ID is u5664317, then switching frequency will be 30+(5+6+6+4+3+1+7) =62 kHz.2Part 2 – Implement and Test Stage 2 ConvertersUse LTSpice to build the Stage 2 converter with open loop control (unregulated), andthen test the converter for all three load types and load sizes. Verify that the converterproduces the required outputs, stays in continuous conduction. Measure the input powerrequired in each load scenario and measure converter efficiency under a range of differentload scenarios. Optional: Implement closed loop/feedback PWM control to automaticallymanage the duty cycle to achieve the required output. Note: it can be harder to get thisright than for the Stage 1 converter – in fact it is recommended to do stage 1 converterfeedback control first.Part 3 – Implement and Test Rectifier and Stage 1 ConverterUse LTSpice to build the Rectifier and Stage 1 converter, complete with closed loop PWMcontrol of the DC-DC converter section (regulated supply). Validate that the circuit worksfor both maximum and minimum output loads and for the maximum and minimum ACvoltages that it can experience. Check that the converter produces the required 24V output,that it stays in continuous conduction and also that there are no high current spikes in thecircuit. Measure the input power required in each load/input scenario, identifying wherethe losses are, and calculate the Rectifier/Converter efficiency. Observe and comment onthe AC supply current waveform.Part 4 – Join the Rectifier/Stage 1 converter and three Stage 2converters and testConnect the Rectifier/Stage 1 converter to two copies of the Stage 2 converter and testunder all real conditions. Comment particularly on whether you are still able to achievethe desired output voltages and low ripple, and if required what you think might do toaddress that. Calculate the combined/overall efficiency of supply to the loads.Comment on what you observe at start-up, that is when you first plug in the powersupply and all output voltages are zero. Do some research and see what can be done inpractice to address this.5 Notes/hints on LTSpice ComponentsDiode: You may pick any available diode, as long as it can handle a large enough forwardcurrent and withstand a large enough reverse bias voltage. The MUR460 is recommended.Inductor: Use the standard inductor, but to make it more realistic include in serieswith it (or define in the inductor specs) a resistance which you must scale with inductancevalue, using 20 mΩ per 100 µH, Figure 2.Switch: Start with a simple generic Switch model (SW), rather than using a FET corIGBT. You won’t then have to worry about maximum current or reverse bias or about3ENGN4625/6625 Major Project, 2015 p4/4 Notes / hints on LTSpice Components: Diode: You may pick any available diode, as long as it can handle a large enough forward current and withstand a large enough reverse bias voltage. I recommend using MUR460. Inductor: Use the standard inductor, but to make it more realistic include in series with it (or define in the inductor specs) a resistance which you must scale with inductance value, using 20 mΩ per 100 µH. Switch: I recommend starting with a simple generic Switch model (SW), rather than using a FET or IGBT. You won’t then have to worry about maximum current or reverse bias or about switching transients (or possible simulation hang-ups). To make it a little more realistic though you should accompany your switch with a 100 mΩ resistor in series with it (this represents the ‘ON’ resistance of the switch). PWM control: When it comes to implementing PWM control of your DC-DC converter you will need to compare the output voltage against a desired value and then against a triangle waveform. For similar reasons as for the switch, I recommend to start with that you use a simple behavioural voltage source (bv) to generate the PWM pulse train. You can input into this any equation you like… you can consider this to be a legitimate software implementation of PWM feedback control. Node labels: It will help, both for plotting and for defining feedback equations, if you label some nodes: Transient simulation time: Make sure that when you measure average values and ripple, and FFT that you ‘ignore’ the transient start-up component. I recommend for the case of the Rectifier and stage 1 converter simulating for at least 5 – 10 lots of 50 Hz cycles. For the Stage 2 converter on its own you will probably not need to simulate for as long. What your project report should contain: Your project report should contain an abstract or summary which describes in summary form what you did: your power supply design, any special features you uses, your observations and results, comments on any difficulties that need addressing, and which extra bits you might have attempted and with what result. Your report should then ideally contain a section for each separate part of the project, detailing for example the design calculations and choices, schematics from LTspice of your final circuit, summary of validated results and measurements, include key waveforms and any unusual observations and what you did to fix them. You should include a short conclusion or discussion section which wraps it all up. Figure 2: Realistic inductor model.switching transients (or possible simulation hang-ups). To make it a little more realisticthough you should accompany your switch with a 100 mΩ resistor in series with it (thisrepresents the ON resistance of the switch), Figure 3.ENGN4625/6625 Major Project, 2015 p4/4 Notes / hints on LTSpice Components: Diode: You may pick any available diode, as long as it can hand e a large enough forward current and withstand a large enough reverse bias voltage. I recommend using MUR460. Inductor: Use the standard inductor, but to make it more realistic include in series with it (or define in the inductor specs) a resistance which you must scale with inductance value, using 20 mΩ per 100 µH. Switch: I recommend starting with a simple generic Switch model (SW), rather than using a FET or IGBT. You won’t then have to worry about maximum current or reverse bias or about switching transients (or possible simulation hang-ups). To make it a little more realistic though you should accompany your switch with a 100 mΩ resistor in series with it (this represents the ‘ON’ resistance of the switch). PWM control: When it comes to implementing PWM control of your DC-DC converter you will need to compare the output voltage against a desired value and then against a triangle waveform. For similar reasons as for the switch, I recommend to start with that you use a simple behavioural voltage source (bv) to generate the PWM pulse train. You ca input into this any equation you like… you can consider this to be a legitimate software impleme tation of PWM feedback control. Node labels: It will help, both for plotting and for defining feedback equations, if you label some nodes: Transient simulation time: Make sure th t when you measure average values and ripple, and FFT that you ‘ignore’ the transie t start-up component. I recommend for the case of the Rectifier an stage 1 converter simulating for at le st 5 – 10 lots of 50 Hz cycles. For the Stag 2 converter o its ow you wil probably not need to simulate for as long. What your project report should contain: Your project report should contain an abstract or summary which describes in summary form what you did: your power supply design, any special features you uses, your observations and results, comments on any difficulties that need addressing, and which extra bits you might have attempted and with what result. Your report should then ideally contain a section for each separate part of the project, detailing for example the design calculations and choices, schematics from LTspice of your final circuit, summary of validated results and measurements, include key waveforms and any unusual observations and what you did to fix them. You should include a short conclusion or discussion section which wraps it all up. Figure 3: Realistic switch model.PWM control: When it comes to implementing PWM control of your DC-DC converteryou will need to compare the output voltage against a desired value and then against atriangle wavefo m. For similar reasons as for the switch, it is recommended to start withthat you use a simple beh vioural voltage source (bv) to generate the PWM pulse train,Figure 4. You can input into this any equation you like… you can consider this to be alegitimate software implementation of PWM feedback control.ENGN4625/6625 Maj r Project, 2015 p4/4 Notes / hints on LTSpice Components: Diode: Y u may pick any available diode, as long as it can handle a large enough forward current and withst nd a large ough reverse bias voltage. I recommend using MUR460. Ind ctor: Use the standard i ductor, but to make it more realistic include in series with it (or define in the inductor specs) a resistance which you must scale with inductance value, using 20 mΩ per 100 µH. Switch: I recommend starting with a simpl g neric Switch model (SW), r ther than using a FET or IGBT. You won’t then hav to w rry about maximum current or reverse bias or about swi ching tr nsients (or po sible simulati n hang-ups). To make it a little more r alistic though you should accompany your switch with a 100 Ω r sistor in series wit it (this represents the ‘ON’ resistanc of the switch). PWM control: When it comes to implementing PWM control of your DC-DC converter you will need to compare the output voltage against a desired value and then against a triangle waveform. For similar reasons as for the switch, I recommend to start with that you use a simple behavioural voltage source (bv) to generate the PWM pulse train. You can input into this any equation you like… you can consider this to be a legitimate software implementation of PWM feedback control. Node labels: It will help, both for plotting and for defining feedback equations, if you label some nodes: Transient simulation time: M ke sure that when yo measure average values and ripple, and FFT that you ‘ignore’ the transient start-up c mpon nt. I recommend for the case of the Rectifier and stage 1 converter simulating for at least 5 – 10 lots of 50 Hz cycles. For the Stage 2 converter on its own you will probably not need to simulate for as long. What your project report should contain: Your project report sh uld contain an abstract or summary which describes in summary form what you did: your power supply design, any special features you uses, your observations and results, comments on any difficulties that need addressing, and which extra bits you might have attempted and with what result. Your report should then ideally contain a section for each separate part of the project, detailing for example the design calculations and choices, schematics from LTspice of your final circuit, summary of validated results and measurements, include key waveforms and any unusual observations and what you did to fix them. You should include a short conclusion or discussion section which wraps it all up. Figure 4: Behavioural switch.Node labels: It will help, both for plotting and for defining feedback equations, if youlabel some nodes, Figure 5.Transient simulation time: Make sure that when you measure average values and ripple,and FFT that you ign re the transient start-up component. For the case of the Rectifiera d stage 1 converter simulating for at ast 5 – 10 lots of 50 Hz cycles is recommended.F r the Stage 2 converter on its own you will probably not need to simulate for as long.4ENGN4625/6625 Major Project, 2015 p4/4 Notes / hints on LTSpice Components: Diode: You may pick any available diode, as long as it can handle a large enough forward current and withstand a large enough reverse bias voltage. I recommend using MUR460. Inductor: Use the standard inductor, but to make it more realistic include in series with it (or define in the inductor specs) a resistance which you must scale with inductance value, using 20 mΩ per 100 µH. Switch: I recommend starting with a simple generic Switch model (SW), rather than using a FET or IGBT. You won’t then have to worry about maximum current or reverse bias or about switching transients (or possible simulation hang-ups). To make it a little more realistic though you should accompany your switch with a 100 mΩ resistor in series with it (this represents the ‘ON’ resistance of the switch). PWM control: When it comes to implementing PWM control of your DC-DC converter you will need to compare the output voltage against a desired value and then against a triangle waveform. For similar reasons as for the switch, I recommend to start with that you use a simple behavioural voltage source (bv) to generate the PWM pulse train. You can input into this any equation you like… you can consider this to be a legitimate software implementation of PWM feedback control. Node labels: It will help, both for plotting and for defining feedback equations, if you label some nodes: Transient simulation time: Make sure that when you measure average values and ripple, and FFT that you ‘ignore’ the transient start-up component. I recommend for the case of the Rectifier and stage 1 converter simulating for at least 5 – 10 lots of 50 Hz cycles. For the Stage 2 converter on its own you will probably not need to simulate for as long. What your project report should contain: Your project report should contain an abstract or summary which describes in summary form what you did: your power supply design, any special features you uses, your observations and results, comments on any difficulties that need addressing, and which extra bits you might have attempted and with what result. Your report should then ideally contain a section for each separate part of the project, detailing for example the design calculations and choices, schematics from LTspice of your final circuit, summary of validated results and measurements, include key waveforms and any unusual observations and what you did to fix them. You should include a short conclusion or discussion section which wraps it all up. Figure 5: Node label.6 What your pr ject report should containYour project report should contain an abstract or summary which describes in summaryform what you did: your power supply design, any special features you uses, your observa-tions and results, comments on any difficulties that need addressing, and which extra bitsyou might have attempted and with what result. Your report should then ideally contain asection for each separate part of the project, detailing for example the design calculationsand choices, schematics from LTspice of your final circuit, summary of validated resultsand measurements, include key waveforms and any unusual observations and what you didto fix them. You should include a short conclusion or discussion section which wraps it allup.5

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