Adjustable Power Supply v18.08
In Progress
Arduino PWM code and voltage sensing
Arduino code is hosted here. This code is far from finalized and represent only one of many possible design approaches. Post as many variations or improvements as you can as long as they have advantages.
Design buck/boost converter circuit/module
Volt-second balance on the inductor means that the average voltage across it over one switching cycle is zero
Discontinuous mode is when current through the output inductor is zero for part of the switching cycle
Figure out ways to salvage or build transformers
Investigate ways to use high frequency for more efficiency in power transformation as well as smaller inductors.
With new Silicon Carbide MOSFET technology, maybe feasible to use flyback transformer at high frequency as described here. A suitable MOSFET for this application costs around $15 but could be offset by smaller transformer.
Design
This page is a great guide.
Applications
Powering 3D printer
Workbench power supply
Charging batteries
Requirements
At least 360W output (12V at 30A)
Adjustable DC voltage output up to 24V
120Vac input
Research
Safety Considerations in Power Supply Design
Fundamentals of Gate Driver Circuits
The Active Clamp Flyback Converter: A Design Whose Time Has Come
A Comparison of Different Snubbers for Flyback Converters
PASSIVE LOSSLESS SNUBBERS FOR HIGH FREQUENCY PWM CONVERTERS (page 41)
Flyback transformer design considerations for efficiency and EMI
Inductor and Flyback Transformer Design
1200 WATT FLYBACK SWITCHING POWER SUPPLY WITH SILICON CARBIDE SEMICONDUCTORS
Inductor volt-second balance, capacitor charge balance, and the small ripple approximation
Understanding Buck-Boost Power Stages
Current Sharing in Parallel Diodes
Open-source based synthetic medium-voltage grid model for distribution power supply systems
Existing Open-Source Projects
Programmable bench power supply EEZ H24005
Modules
Flyback Transformer
A flyback transformer would most likely be operated in continuous conduction mode, so transformer size will be limited by core saturation. A toroid with powder core could be a suitable solution.
Switching speeds of MOSFET and diodes should be minimized to reduce switching losses. Winding losses should be minimized as well.
Selecting a Distributed Air-Gap Powder Core for Flyback Transformers
Conceptual Design
These designs may not be safe or functional. Use at your own risk.
Flyback Configuration
https://wiki.opensourceecology.org/images/thumb/f/fc/FlybackDraft.jpg/800px-FlybackDraft.jpg [1]
DRAFT, values are not correct
10 gauge wire for secondary winding. Primary has 8.5 turns, try 3 or 3.5 for secondary.
Software
Possible Parts
Output Capacitor: Aluminum (cheaper but more lossy), organic semiconductor (good overall), tantalum (best for surface mount) [2]
Output Inductor: Bobbin or rod-core cause more noise [3]
Forward Configuration
Transformer: XFRMR TOROIDAL 500VA CHAS MOUNT, Investigating ways to salvage transformers
Rectifier: RECT BRIDGE FAST 3PHASE I4-PAC-5
IRFP250NPower transistor (MOSFET) driven by TC1411 1A High-Speed MOSFET Driver with pulse signal originating from arduino.
(Alternative mosfets requiring no mosfer driver) IRF540N "IR" MOSFET N-Channel 33A 100V IRFP250N
Flyback Configuration
Bridge Rectifier: 50A, 600V BRIDGE RECTIFIER, GBJ, DIODE BRIDGE FAST DIODE ECO-PAC1, 50A, 1000V BRIDGE RECTIFIER, GBJ
Input Capacitor: CAP ALUM 18000UF 20% 160V SCREW
Snubber Diode: DIODE SCHOTTKY 250V 40A TO220AB
Snubber Capacitor: CAP CER 0.18UF 250V X7R 1812
Active Snubber Control: Active clamp flyback controller UCC28780D
Gate Driver Transistors: TRANS NPN 60V 3A TP, TRANS PNP 60V 5A TO-126
Integrated Gate Driver: IC DRIVER HI/LO SIDE 600V 14-DIP
Switching Transistor: MOSFET NCH 650V 21A TO247N, MOSFET NCH 650V 39A TO247N
Transformer: FIXED IND 10UH 16.9A 5.1 MOHM TH, Kool Mu 77130A7 (11.2mm outer diameter, permeability = 125 u)
Output Diode: DIODE SCHOTTKY 45V 60A TO247AD
Cost of components ~$70